This study investigated the relationship between training-load (TL) metrics and the acute performance decrement (APD) measured immediately after 4 training sessions performed by well-trained runners.

On a treadmill, 12 well-trained runners (10 men and 2 women) performed an incremental test, a baseline time-to-exhaustion (TTE) test at maximal aerobic speed, and 4 randomized training sessions followed by a TTE test to measure APD. The training sessions were matched for external load (60 arbitrary units) but differed in the time spent in the 3 intensity domains. The TL metrics used were based on training impulse, heart-rate variability, ratings of perceived exertion, and the NASA Task Load Index (NASA-TLX) rating scale.

TTE was significantly shorter after all the training sessions compared with baseline (P < .001). While APD was higher (+16%, P = .035) for long-duration high-intensity training (HITlong) compared with low-intensity training (LIT), most TL metrics showed higher values (P < .001) in LIT than in HITlong. Conversely, NASA-TLX values were higher (P < .001) in HITlong than in LIT and were significantly associated with APD values (P < .001, β = 0.54). Physiological parameters showed that less time was spent above 90% of V˙O2max during LIT compared with the other training sessions (P < .01), while average respiratory frequency and mean respiratory exchange ratio were higher during HITlong compared to LIT (P < .01).

APD was observed after the 4 running training sessions, and it was not associated with most of the TL metrics. Only NASA-TLX was associated with APD, suggesting that this TL metric could be leveraged for training monitoring.

The polar verity sense (PVS) is a user-friendly heart rate monitoring tool for field-based research compared to Polar H10. However, its validity in the real world (e.g., school settings) among children and adolescents is yet to be determined. Thirty-nine adolescents (12.2 ± 0.4 years, 25 males) participated in a 6-min resistance-based high-intensity interval training (HIIT) session. Heart rate was simultaneously measured by PVS and Polar H10 (criterion measure). Validation metrics included within-participant correlation, mean absolute error, mean absolute percentage error and Bland-Altman plots. Overall, PVS showed very strong within-participant correlation (r = 0.93, p < .001) with Polar H10. The mean absolute and percentage error was 4 b·min-1 and 2.8%, respectively. The correlation between PVS and Polar H10 decreased (r = 0.84, p < .001) for data above the HIIT intensity threshold (≥80% maximal heart rate) but maintained a strong relationship. The validity of PVS remained similar when accounting for sex, body mass index, waist circumference or cardiorespiratory fitness. PVS demonstrated strong agreement with Polar H10 in monitoring heart rate during HIIT in adolescents within a school setting. Therefore, it is valid to replace traditional inconvenient chest strap heart rate monitors with a practical and ergonomic armband PVS, which could largely enhance the feasibility of HIIT fidelity monitoring.

To investigate the competitive demands and performance-determining variables in the Sprint and Mixed-Relay formats in male and female ski mountaineers.

Performance data of 76 ski mountaineers (36 females) competing in a World Cup event were analyzed. A total of 20 ski mountaineers (11 females) completed ski-mountaineering-specific maximal and supramaximal (intensity > VO2max) tests, with a subgroup of 10 ski mountaineers (5 females) being monitored during the races.

Near-maximal cardiac responses (>95% of maximal heart rate) were observed in the 2 formats, with significantly higher ascent speed and contribution of lactic anaerobic metabolism in the Sprint than in the Mixed Relay (blood lactate 12.9 [3.2] vs 6.3 [1.2] mmol/L, P < .001). Uphill skiing represented the majority of race time in both formats and accounted for most of the variance in performance (∼80%-90%), with transition times explaining almost all the remaining variance (∼10%-15%). In the Mixed Relay, the skiing speed at the second ventilatory threshold (R2 = .78, P = .001) and the maximal speed at the end of the VO2max test (R2 = .78, P = .019) were the best predictors of performance in the whole pool of ski mountaineers and in males, respectively. The maximal sustainable skiing speed over a 2-minute effort was the best predictor of performance in the Sprint (R2 = .95, P < .001) for both sexes.

Ski mountaineers should tailor their training considering the specific physiological demands of each race, emphasizing near-maximal to maximal intensities for the Mixed Relay and supramaximal intensities for the Sprint. These insights into Olympic ski-mountaineering disciplines are of considerable value for athletes and coaches in preparation for the Winter Olympics.

In previous studies comparing different interval protocols for high-intensity interval training, large differences in time above 90% of maximal oxygen consumption (V˙O2max) have been observed. Differences can possibly be attributed to session design or intensity control. Twelve well-trained cyclists and triathletes (V˙O2max: 68 [6.3] mL·min-1·kg-1) performed 2 different cycling ergometry interval protocols of 3 × 13 × 30/15 seconds (short interval [SI]) and 6 × 5 minutes (long interval [LI]), each with a fixed intensity based on percentages of maximal aerobic power and self-paced approach with maximal effort. The time above 90%V˙O2max was significantly greater for SI than LI in fixed (P < .01) but not in self-paced intensity (P = .321). All physiological parameters assessed and power outputs were higher in self-paced than fixed (all P < .001; all ηp2>.795), resulting in an increased time above 90%V˙O2max for SI (1130 [204] vs 420 [259] s) and LI (1016 [312] vs 178 [159] s). When the short recovery periods are included in total interval work duration in SI, and SI and LI are matched on duration and fixed intensities (similar percentage of maximal aerobic power), SI gave greater time above 90%V˙O2max. However, when SI and LI were performed with the self-paced approach and maximal effort, the exercise intensity became higher and there were no differences in time above 90%V˙O2max.

Physical activity (PA) is widely known for its outstanding benefits across several health domains including physical, psychological, social, and cognitive in children and adolescents. However, global trends indicate how low levels of PA and physical fitness among adolescents are increasing, with over 80% failing to meet the World Health Organization (WHO) guidelines of 60 min of moderate-to-vigorous physical activity (MVPA) daily.

This study aimed to evaluate the effects of an 8-week high-intensity interval training (HIIT) intervention based on strength and endurance trainings protocols during physical education (PE) classes on body composition, physical fitness, and cognitive functions in adolescents aged 13-17 years. A quasi-experimental pre-post design was employed with experimental group (EG) and control group (CG).

Results indicated significant improvements in the EG in cardiorespiratory fitness (VO2max), strength (hand grip, horizontal jump), and speed-agility (4 × 10 m test). Cognitive outcomes assessed via the D2 attention test revealed notable enhancements in concentration, a reduction in errors, and improved processing speed in the EG relative to the CG (p > 0.05).

Future studies should explore the long-term impacts of HIIT on cognitive growth and academic achievement, as well as determine the ideal duration and frequency of sessions to optimize benefits in various educational contexts. The results obtained reinforce the use of HIIT in school environments and are further research on its application.

To examine the acute physiological, perceptual and neuromuscular responses of team sport athletes to two volume-matched cycling high intensity interval training (HIIT) sessions with short work bouts (< 60 s).

Using and randomised crossover design, 16 male team sport players completed 2 × 6 min (with 5 min between sets) repeated efforts of 15 s or 30 s exercising at 120% power at V ˙ O2 max (p V ˙ O2 max) followed by matched-duration passive recovery on a cycle ergometer.

Absolute mean V ˙ O2 (p = 0.0257) and relative mean V ˙ O2 (p = 0.0275) were higher in 15 s than 30 s HIIT. Total time at > 90% V ˙ O2 max during the HIIT was higher for 15 s compared to 30 s HIIT (p = 0.0257). Heart rate remained the same between trials (p = 0.805) as did oxygen pulse (p = 0.1161). B[La] was lower in 15 s compared to 30 s HIIT (p = 0.0257). Differences in dRPE-L (p = 0.0495), dRPE-B (p = 0.0495) and dRPE-O (p = 0.1837) suggested lower perceived exertion in 15 s compared to 30 s HIIT. Maximal isometric knee extension force revealed a greater reduction after 30 s HIIT (p = 0.0495).

Team sport athletes using short duration cycling-based HIIT should use 15 s work intervals to elicit greater time working near V ˙ O2 max at a lower perceived exertion and with smaller reductions in peak muscle force after exercise.

The aim of this study was to explore sex differences in neuromuscular fatigue during a severe-intensity cycling exercise. Twenty-four healthy participants (12 women and 12 men) cycled at 80% of the difference between gas exchange threshold and maximal power output to the limit of tolerance. Neuromuscular fatigue was assessed by the decrease in maximal voluntary contraction of the knee extensors before and after exercise, and central and peripheral fatigue was measured by the decrease in voluntary activation and quadriceps potentiated twitch force before and after exercise. Women presented shorter time to task failure (P=0.025) and lower levels of neuromuscular fatigue (P=0.006) and peripheral fatigue (P<0.001) than men. Women and men showed different patterns of muscle activation during exercise, with women presenting greater muscle activation at the beginning of exercise and sustaining this elevated muscle activation throughout exercise, while men increased muscle activation from the beginning to the end of exercise. In conclusion, women had lower levels of neuromuscular fatigue, mainly caused by lower levels of peripheral fatigue, and a different muscle activation pattern in an exhaustive severe-intensity cycling exercise.

The numerous health benefits of exercise are well-documented, including its efficacy in treating substance use disorders (SUDs). Several exercise regimens have been proposed; however, the most effective regimen for patients with addiction has yet to be elucidated. High-intensity interval training (HIIT) exhibits considerable potential compared to aerobic and resistance exercise. Dopamine signaling is recognized as a key neurobiological mechanism contributing to HIIT's therapeutic potential for SUDs; however, the role of the endocannabinoid system in this context is not well understood. The present study investigated the effects of HIIT exercise on endocannabinoid signaling by measuring cannabinoid receptor 1 (CB1R) binding in the brains of male and female rats using [3H]SR141716A autoradiography. Male and female rats were separated into sedentary and HIIT exercise groups. For six weeks, exercise was completed daily on a treadmill for 30 min (10 3-min intervals) progressively increasing speed to 0.8 mph (21.5 m/min). The HIIT program significantly reduced CB1R binding in both sexes across multiple brain regions, including the striatum, thalamus, and distinct areas of the cortex. Sex differences were observed wherein males exhibited greater CB1R binding than females across brain regions, including the cerebellum, striatum, and parts of the cortex. Males experienced an increase in mean cerebellum CB1R binding due to HIIT, whereas females showed no effect in this region. The results suggest HIIT exercise can modulate endocannabinoid signalling by way of decreased CB1R binding. These findings further support the intensity dependence of endocannabinoid modulation and highlight potential pathways for exercise-induced neurobiological and behavioural change.

In rowing, the effectiveness of adding high-intensity interval training (HIIT) to moderate-intensity continuous training (MICT) within the weekly training program on physiological adaptations and performance is still unclear. This study compared the effects of HIIT plus MICT (MIXED) versus MICT alone on physiological/metabolic responses and performance in adolescents.

Twelve highly trained adolescent rowers (age: 15.7 [0.5] y) were divided into 2 groups: MIXED and MICT. Before and after a 7-week intervention period, rowers underwent an incremental step test to determine peak oxygen uptake (VO2peak), power at VO2peak (WVO2peak), power corresponding to a lactate concentration of 2 and 4 mmol·L-1, power output at lactate threshold, oxygen uptake at the second lactate threshold (VO2LT), and peak oxygen pulse. Training load from TRIMP was also measured. The training intervention consisted of 7 sessions per week including 2 "off-water," 3 "on-water," and 2 resistance-training sessions. The "on-water" and resistance-training sessions were the same for both groups, while during "off-water" sessions, the MIXED group performed HIIT (4 × 4 min at 85% WVO2peak) and the MICT group performed moderate-intensity training (80 min at 70% WVO2peak).

Statistical analysis showed that in the MIXED group, VO2LT was significantly increased and training load from TRIMP was significantly reduced (P < .00001) compared with the MICT group (P = .008). Both groups similarly improved VO2peak, peak oxygen pulse, WVO2peak, power output at lactate threshold, and power corresponding to a lactate concentration of 2 and 4 mmol·L-1.

Our findings showed that, in adolescent rowers, MIXED training enhanced VO2LT, thus indicating HIIT as a valid and time-efficient addition to traditional MICT. However, given that adolescents were examined, data should be interpreted with caution, as training and/or growth/maturation may have contributed to performance changes.

High-intensity interval training (HIIT) in hypoxia has demonstrated superior increases in aerobic capacity (VO2 max) adaptations, but this has not been explored in distance runners. This study examined the methodological and VO2 max adaptations of HIIT under different altitude conditions in distance runners. We searched the PubMed, ProQuest, Europe PMC, ScienceDirect, and Cochrane databases until August 2024. Among the 1183 reviewed studies, six studies were included. The PEDro score determined the methodological quality, and a meta-analysis was performed using Jamovi software. The results revealed that VO2 max improved more in hypoxic (4.4%-13%) HIIT than in normoxic (1%-8.3%) HIIT. The meta-analysis results revealed that the effect of HIIT under hypoxia on the VO2 max overall standardized mean difference (SMD) was 0.68, with a 95% confidence interval [0.3, 1.06], p < 0.001. Conversely, the pooled SMD was not related to the type of hypoxia (p = 0.4), training status (p = 0.36), intervention week (p = 0.82), and sex (p = 0.32). In conclusion, HIIT under hypoxia achieves a greater VO2 max improvement than normoxia. Endurance athletes and coaches could plan to benefit from such training. However, studies on females using different HIIT protocols and participants at different natural altitudes are limited. This review is registered under the PROSPERO CRD42024578473.

This study aimed to assess relationships of acute responses to short-format high-intensity interval training (HIIT) with the anaerobic speed reserve (ASR) of adolescent runners.

Pre-post intervention design.

Eighteen highly-trained youth runners (15.83 ± 0.86 years) underwent maximal sprinting speed (MSS) and maximal aerobic speed (MAS) assessments to determine ASR (MSS minus MAS) and a standardized HIIT protocol (2 × (20 × 15 s/15 s @110 % MAS)) was administered. Pre/post-HIIT assessments included biochemical (i.e., creatine kinase (CK)), neuromuscular (countermovement jump, CMJ; reactive strength index, RSI), cardiac (i.e., heart rate recovery (HRR)), and athlete-reported outcome measures (e.g., single item for fatigue). Pearson's r was calculated to assess relationships between acute responses and ASR, MSS, MAS, and relative intensity of the HIIT (%ASR).

Athletes' ASR and %ASR were significantly associated with the pre/post difference of CK (r = -0.75; p < 0.001; r = 0.74; p < 0.001, respectively), CMJ height, and RSI (r ≥ 0.69; p ≤ 0.002; r ≤ -0.49; p ≤ 0.04, respectively). However, HRR did not correlate significantly with ASR or %ASR (r ≤ 0.37, p ≥ 0.131, r ≥ -0.31; p ≥ 0.22, respectively). The pre/post difference of RSI correlated with MAS (r = -0.54; p = 0.02), and the pre/post difference of CK (r = -0.50; p = 0.034) and of CMJ height (r = 0.76; p < 0.001) with MSS. Regarding athlete-reported measures, ASR and %ASR showed significant associations with most fatigue and recovery variables (r ≥ 0.57; p ≤ 0.014, r ≥ 0.57; p ≤ 0.013, respectively). The pre/post difference of the single item for fatigue showed a positive relationship with MSS (r = 0.49; p = 0.037).

Acute biochemical, neuromuscular, and athlete-reported responses to short-format HIIT showed strong relationships with ASR and MSS, indicating higher internal load in athletes with a lower ASR and MSS by using a higher %ASR, compared to athletes with a higher ASR and MSS. These findings can help to tailor training programs to individual needs and avoid possible overload.

Affective valence is typically positive at exercise intensities below the lactate threshold, yet more aversive responses occur at supra-threshold intensities. Nevertheless, the physiological and psychological predictors of affective valence during supramaximal intensities including short sprint interval training (sSIT) have not yet been elucidated. Seventeen (7 women/10 men) moderately active young adults (age ​= ​[28.2 ​± ​5.6] years;V ˙ O2max [maximum oxygen consumption] ​= ​[52.9 ​± ​8.1] mL·kg- 1·min- 1; BMI [body mass index] ​= ​[24 ​± ​2] kg·m- 2) completed four low-volume running sSIT sessions (10 ​× ​4 ​s efforts with 30 ​s of passive recovery). We recorded participants' heart rate (HR), root mean square of successive differences of normal RR intervals (RMSSD), heart rate recovery (HRR), ratings of perceived exertion (RPE), feeling scale (FS), intention and self-efficacy during, and after each session. Overall, no significant correlation (p ​> ​0.05) was found between FS and baseline clinical outcomes. No significant correlation (p ​> ​0.05) was detected between FS and any training parameter. No significant correlations were noted between FS and exercise task self-efficacy and intentions (p ​> ​0.05). The regression model was significant (F 3,61  ​= ​5.57; p ​= ​0.002) and only three variables significantly entered the generated model: ΔHRRend-120s end (p ​= ​0.002; VIF ​= ​2.58; 40.8%), time ≥ 90% HRpeak (p ​= ​0.001; VIF ​= ​1.26; 31.6%), and RMSSDend (p ​= ​0.025; VIF ​= ​2.23; 27.6%). These findings suggest that HR-based measures, particularly those related to in-task stress (time ≥ 90% HRpeak) and acute recovery (ΔHRRend-120s end, and RMSSDend), may predict affective valence during real-world sSIT.

This study aimed to evaluate the impact of Fixed-Role Small-Sided Games (FRSSGs) on youth soccer players' agility and its components: reaction time, linear speed, and change-of-direction speed (CODS).

Thirty-one male U-12 regional soccer players were randomly assigned to the FRSSG group (n = 16; age: 10.63 ± 0.48 years) or the control group (CON) (n = 15; age: 10.89 ± 0.31 years). The intervention program lasted 18 weeks. Pre- and post-intervention tests assessed reaction time, linear sprint speed (10 m and 20 m), CODS (505 and zig-zag tests with/without the ball), and agility (Y-shaped with/without the ball and multiple-signal tests). Statistical analysis included paired t-tests, repeated measures ANOVA, and effect sizes (Cohen's d).

Significant baseline differences were observed between groups in 10-meter linear speed, and zigzag test performance (p < .05). Within-group improvements were observed for the FRSSG group in the 505 Test (-6.85%, p < .001, d = 1.375), Zigzag Test (-10.77%, p < .001, d = 2.148), CODS Zigzag Ball Test (-9.42%, p < .001, d = 1.434), Y-shape Ball Test (-9.49%, p < 0.001, d = 2.195), and Agility Multi-signal Test (-8.42%, p = .002, d = 0.821). Significant between-group differences favoring FRSSG were found for the 505 Test (p = 0.005, η 2 = 0.038), Zigzag Test (p < .001, η 2 = 0.435), CODS Zigzag Ball Test (p = 0.004, η 2 = 0.04), and Y-shape Ball Test (p = 0.006, η 2 = 0.027).

FRSSGs have been shown to effectively enhance agility and change of direction speed, both with and without the ball, in youth soccer players.

High-intensity interval training (HIIT) has gained recognition for its positive impacts on cardiovascular (CV) health, metabolic outcomes, mental health, and quality of life (QoL). This narrative review aims to comprehensively evaluate the efficacy of HIIT in enhancing CV health and preventing CV disease (CVD).

A comprehensive search of PubMed identified 257 articles, of which 39 studies met predefined inclusion and exclusion criteria for quality assessment. Key metrics evaluated included blood pressure, vascular function, lipid profiles, body composition, and CRF.

HIIT significantly improved vascular function, evidenced by reductions in systolic and diastolic blood pressure and enhanced flow-mediated dilation. Improvements in cardiac function were observed through increased cardiac output and heart rate variability. Additionally, HIIT positively influenced lipid profiles, decreasing low-density lipoprotein and triglycerides while increasing high-density lipoprotein. Significant reductions in body fat and improvements in VO2peak were noted, contributing to enhanced CRF. HIIT also positively impacted mental health and QoL, reducing anxiety and depressive symptoms. Importantly, HIIT was safely and effectively applied to high-risk populations-individuals with obesity, metabolic syndrome, CVD, and cancer survivors-with a low incidence of adverse effects.

This review highlights HIIT as an effective and safe exercise modality for improving CV health, metabolic indicators, mental health, and QoL. Future research should focus on developing tailored HIIT protocols to optimize adherence and efficacy across diverse populations, considering variations in age, sex, health status, and underlying medical conditions.

Intense interval exercise training induces various physiological and metabolic adaptations related to performance and health. For designing a program, the F.I.T.T. principle, referring to frequency, intensity, time, and type of exercise, can be used to manipulate the level of physiological stress in the body, leading to various adaptations. Modifying these four parameters results in a wide range of interval protocols that are safe and effective for different populations including athletes and individuals with chronic diseases. In this review, we present how the manipulation of the F.I.T.T. components can alter the acute and chronic cardiorespiratory, metabolic, perceptual, and affective responses and adaptations to intense interval exercise training. From this evidence, it appears that the duration of the exercise bout and recovery interval are critical parameters for the manipulation of almost all acute responses, enabling periodization of intense interval exercise training, and promoting optimal adaptations and exercise adherence. In addition, a considerable level of adaptations may be achieved with training frequencies as low as once or twice per week and with lower than maximal intensities, adding to the feasibility of this exercise mode. Overall, by varying these parameters, the design of an intense interval exercise training program can be tailored according to the needs and abilities of each individual, and an optimized training prescription may be achieved.

Predictions of performances should be evaluated to confirm their accuracy. Work by this group has resulted in 3 sets of predictions being generated for swimming events at the Paris 2024 Olympic Games, using the same statistical approach for each set.

To examine the accuracy of swimming predictions for the Paris 2024 Olympic Games and generate updated predictions for both the Singapore 2025 World Aquatics Championships and Los Angeles 2028 Olympic Games.

A linear regression and forecasting function was used to generate predictions for the Paris 2024 Olympic Games across 3 performance categories (rank 1st-3rd, 4th-8th, and 9th-16th). Mean absolute error was used to assess the accuracy of the predicted versus actual Paris 2024 Olympic Games times for all events across the 3 performance categories. New predictions for the 2028 Olympic cycle were subsequently generated using results from the World Championships and Olympic Games between 2011 and 2024.

Across all events, a mean absolute error value of 0.84% was observed between the Paris 2024 Olympic Games predicted and actual times. Predicted times were highly correlated with actual times (r2 = .99). Across the 3 sets of predictions (created in 2022, 2023, and 2024), the 2023 set of predictions had the lowest overall mean absolute error value (0.55%).

The methods used to create predictions for swimming performances at the Paris 2024 Olympic Games were deemed accurate. These methods enable national swimming federations to create a series of predictions for a given major championship, inform athlete identification and development pathways, and allocate appropriate resources, including sport-science provision.

This study aimed to investigate differences in match physical and technical/tactical performance of teams across different competitive levels in international soccer: FIFA Men's World Cup Qatar 2022 (MWC), FIFA U20 World Cup Argentina 2023 (U20WC), and FIFA U17 World Cup Indonesia 2023 (U17WC).

From a total of 168 games, 138 games were analyzed (N = 276 game observations) using an optical tracking system.

On average, the U17WC teams exhibited reduced total running (3% less), high-intensity running (14%-16% less), and sprinting (18%-26% less) distance than the MWC and U20WC teams (P ≤ .0023; effect size [ES]: 0.8-1.5). The MWC teams displayed 4% to 5% higher accuracy in passing and executing line breaks (P ≤ .0188; ES: 0.6-0.7), along with increased offers to receive the ball (53%-118% more) and movements to receive the ball (44%-101% more), and received the ball (61%-137%) more often than the U20WC and U17WC teams (P < .001; ES: 1.1-2.1). Moreover, notable decreases in defensive pressure (-18% to -32%) and forced turnovers (-26% to -32%) were observed in the U17WC than other competitions (P ≤ .0001; ES: 0.8-2.2). Greater variability was observed among the U17WC teams in several metrics, including high-intensity/sprinting distances, attempts at goal, and receptions in the final third.

These findings demonstrate that as the competitive level increases, so do the physical demands, advanced technical skills, and tactical fluidity/adaptability. However, caution should be exercised when interpreting match performance of younger age groups, as higher variability was evident in both physical and technical/tactical performance in matches.

To evaluate the within-athlete sensitivity, validity, and dose-response relationships of exercise heart rate (HRex) from a submaximal fitness test (SMFT) as a proxy measure of cardiorespiratory fitness.

This study follows an observational, repeated-measures design. Twenty-five trained female football players' training loads (GPS and HR metrics) were collected throughout an 8-week preseason period. A 4-minute continuous-fixed SMFT protocol was administered weekly to evaluate HRex. A running time-trial assessment was conducted in weeks 2 and 8 to calculate mean velocity (5-min-30-s time-trial mean velocity) as a proxy measure of cardiorespiratory fitness. SMFT HRex measurement properties were determined via within- and between-athletes correlations and linear mixed models.

The overall preseason change in SMFT HRex derived from weekly repeated measures was -4.7% points (90% CIs, -3.9 to -5.6). The association between SMFT HRex and 5-minute-30-second time-trial mean velocity changes was large (-0.55), with 90% CIs ranging from negative moderate to negative very large magnitudes (-0.31 to -0.71). A 1% point decrease in SMFT HRex corresponded to an increase in 5-minute-30-second time-trial mean velocity of 0.13 (90% CIs, 0.03-0.24) km·h-1. Within-athlete correlations between training loads and SMFT HRex demonstrated moderate inverse relationships with external-load parameters (-0.39 to -0.47) and small inverse relationships with HR-based internal metrics (-0.25 to -0.29). Accumulated high- and very high-speed running throughout the entire preseason showed consistent inverse dose-response relationships with SMFT HRex (moderate and large, respectively), while all other load measures displayed unclear associations.

SMFT HRex is a sensitive and valid tool to evaluate preseason cardiorespiratory-fitness changes in female football players.

Athletes often use sport supplements to improve their physical and physiological performance. This randomized, double-blind, placebo (PL) -controlled study aimed to investigate the effects of combined versus single supplementation of creatine (Cr), beta-alanine (BA), and L-citrulline (L-Cit) during short sprint interval training (SSIT) on basketball players' physical and physiological performance over a period of 28 days.

Forty-eight basketball players were equally assigned to 6 groups of Cr (0.1 g/kg of Cr monohydrate daily), BA (4.8 g daily), L-Cit (6 g daily), combined supplementation, PL, and an active control group, and each group consisted of 8 participants. The training groups participated in SSIT (3 sets of 10 repetitions of 5-s all-out runs) sessions 3 times a week for 4 weeks. Physical (vertical jump, 20-m sprint, Illinois change of direction) and physiological (Wingate anaerobic power and cardiorespiratory fitness test) performance were evaluated before and after the training period.

All training groups (Cr, BA, L-Cit, combined, and PL) showed significant improvements in physical and physiological performance over the 4-week intervention (P < .05). Interestingly, the supplement groups displayed significantly (P = .001) greater changes than the PL group, indicating better outcomes in performance adaptations. However, significant differences in performance variables were observed among the supplement groups.

Our findings indicate that short-term supplementation with Cr, BA, and L-Cit, as well as a combination of them during SSIT, can significantly improve the physical and physiological performance of basketball players compared to a PL.

To investigate the effect of different work: rest durations on physiological, neuromuscular, and perceived exertion responses during taekwondo-specific high-intensity interval training (HIIT).

Thirteen moderate-trained taekwondo athletes (age: 21.7 ± 2.4 years; body mass: 69.1 ± 7.6kg; height: 174 ± 6 cm) completed a familiarization session and three HIIT trials. The trial consisted of three rounds of 2 min roundhouse kicks with 1 min of rest in between. In each round, the work: rest ratio was constant at 1:2, and the work: rest duration varied to be: short (2s:4s), medium (10s:20s), and long (20s:40s). Heart rate (HR) and oxygen uptake (V ˙ O2) were continuously measured. Blood lactate concentration ([La-]), countermovement jump (CMJ), and rating of perceived exertion (RPE) were recorded before trials and after each round. Energy contribution was estimated.

HR,V ˙ O2, and CMJ were similar across protocols (P > .05) but, [La-] was higher during long than short work: rest duration protocol (P < .05). Relative aerobic energy contribution and RPE in round 3 were higher during long than short work: rest duration protocol (P < .05). Absolute and relative glycolytic energy contribution in rounds 1 and 2 were higher during long than short work: rest duration protocol (P < .05). Relative phosphate energy contribution in rounds 1 and 3 was lower during long than short work: rest duration protocol (P < .05).

Different work: rest durations of taekwondo-specific HIIT influenced [La-], energy system contributions, and RPE. The longer work: rest duration protocol (20s:40s) stressed more the glycolytic, aerobic energy systems and perceived exertion, and less the phosphagen energy system.

To explore the inhibitory function characteristics of overweight female college students through two studies, and on this basis, to explore the effects of high-intensity interval training (HIIT) intervention on the inhibitory function of overweight female college students, as well as to test the mediating role of body composition.

Study I recruited 34 overweight female college students and 38 normal-weight female college students, using the GO/NOGO task and the Flanker task to measure the participants' response inhibition and interference inhibition. Study II randomly divided the recruited 64 overweight female college students into an experimental group (n = 32) and a control group (n = 32), with the experimental group undergoing 8 weeks of Tabata-based HIIT and the control group not engaging in any form of exercise. The body composition of the participants was measured using a bioelectrical impedance body composition analyzer made in South Korea, the GAIA KIKO. Based on the SPSS 21.0 software, statistical techniques such as independent sample t-tests, Pearson correlation analysis, and mediation effect tests were used for analysis.

The reaction times of overweight female college students were significantly shorter than those of normal-weight female college students under the GO stimulus, consistent conditions, and inconsistent conditions (P < 0.05). 8 weeks of HIIT could effectively reduce the reaction times of overweight female college students under the GO stimulus, consistent conditions, and inconsistent conditions (P < 0.05), and effectively improve BMI, fat-free weight, fat content, muscle content, and basal metabolic rate (P < 0.05). There was a significant positive correlation between fat content and reaction times under the GO stimulus, consistent conditions, and inconsistent conditions (P < 0.05), and a significant negative correlation between waist-hip ratio and reaction times under the GO stimulus (P < 0.05). In addition, the mediation effect test found that fat content had a significant mediating effect in the reaction times under the consistent conditions after HIIT intervention (P < 0.01).

Overweight female college students have poorer inhibitory function, and HIIT can effectively improve their inhibitory function, with fat content playing a potential mediating role in the intervention process. It is recommended that HIIT be used as an important means to control the weight of overweight female college students and improve their inhibitory function.

Interest in 'exercise snacks' has increased, yet a comprehensive and holistic review of this novel concept is lacking. We aimed to map global research on 'exercise snacks', across youth, adult and clinical populations through a scoping review.

A systematic search was conducted in six databases. Grey literature searches were also conducted. Studies whereby participants were prescribed a structured bout of intense exercise dispersed across the day, or the exercise was explicitly defined as a form of 'snacks', in any setting were included. We used the Consensus on Exercise Reporting Template (CERT) to assess the completeness of exercise descriptions. Data were recorded into spreadsheets, then descriptively analyzed and summarized in graphic form.

The 45 publications meeting our inclusion criteria represented 33 original studies. These 33 studies enrolled a total of 1118 participants, with a median sample size of 24. Studies were categorized as either acute (n = 12) or chronic (n = 21) trials with both trial types performed across a wide range of participant ages (range 8.7 to 78 years) but mostly conducted on healthy adults and older adults. The majority of studies (20/33) defined the concept as 'exercise snacks', with study context being predominantly the laboratory or home. A wide variety of exercise modes (e.g., cycling, stair climbing, body weight exercises) and comparator conditions (e.g., moderate intensity continuous exercise, prolonged sitting, non-exercise controls) were used. 'Exercise snack' intensity was prescribed more frequently than it was reported, and, of the available data, mean intensity was estimated at 76.9% of maximal heart rate and 5.2 Arbitrary Units (AU) on the Ratings of Perceived Exertion (RPE) CR10 scale. Study outcome measures were predominantly cardiovascular, metabolic, muscular, and psychological, with studies mostly adhering to the CERT, though there was underreporting of detail for the exercise provider, motivation strategies, adverse events and intervention fidelity.

The 'exercise snack' concept is being increasingly used to cover an array of exercise models. The most common protocols to date utilize body weight exercises or stair climbing. We recommend 'exercise snacks' terminology is consistently used to describe protocols whereby short, purposeful structured exercise is dispersed throughout the day. Future studies should provide detailed descriptions of their 'exercise snacks' model, through exercise and adverse event reporting checklists.

This study aimed to evaluate mechanical and physiological responses to all-out high-intensity interval training (HIIT) sessions (10 maximal efforts of 30 seconds each with 4 min of rest) performed against different resistance forces on a one-leg knee extension ergometer. Eighteen men conducted an incremental test to determine the resistance associated with its maximal power (Rmax), followed by all-out HIIT sessions at 120%, 160%, and 200% of Rmax, while oxygen consumption and neuromuscular function were measured. Mechanical power output was higher during the session at 200% of Rmax compared to the other sessions (p < 0.001), but its absolute anaerobic energy contribution was similar to that at 160% of Rmax. Notably, the all-out efforts at 200% Rmax led to inconsistent kicking cadence and some participants were unable to complete the session. Therefore, 160% Rmax was the highest suitable resistance force for a consistent all-out HIIT session on a knee extension ergometer.

In this study, we examined whether the 0-10 rating of perceived effort (RPE) scale can serve as a method for prescribing playing intensity in small-sided games (SSGs). We conducted a randomized crossover trial involving 25 young male football players (age range 16-18 years). Participants completed a familiarization and three experimental sessions where game intensity was regulated using prescribed intensities equal to RPE of 6, 8, or 10. Each session involved six teams of three players playing in three SSGs, with 4 min of rest, in a playing area of 133 square meters per player. Outcomes included total distance, high-speed running distance (HSRD), intense acceleration and deceleration (IAD) counts, and average heart rate (HR). We fitted mixed models and estimated 95% confidence intervals (CIs) to analyze the results. The CIs for all locomotive outcomes indicated an increase at RPE-8 and RPE-10 compared to RPE-6. Notably, the effects on HSRD and IAD were substantial, with differences between RPE-10 and 8 to RPE-6 ranging from 28% to 97%. Conversely, differences in the total distance the players covered per game between RPE-10 and 8 to 6 were minor (~5%). We could not identify clear differences between RPE-10 and 8 in the locomotive outcomes (differences range 0%-9.6%, CIs containing zero) nor in HR across all RPE conditions (differences range 1-3.5 bpm, CIs containing zero). We conclude that RPE can serve as a practical tool to prescribe medium or high intensity during SSGs, although its ability to differentiate between higher intensity levels or influence heart rate is limited.

This study aimed to evaluate the effects of an 8-week concurrent training (CT) program that combined short sprint interval training (sSIT) and resistance training (RT) in alternating sequences (i.e., sSIT + RT or RT + sSIT) on the physical fitness, aerobic capacity, and anaerobic performance of male karate athletes, in comparison to each training intervention conducted independently. Forty national-level young male athletes volunteered to participate in this study and were divided into sSIT, RT, sSIT + RT, RT + sSIT, and active control (CG) groups, each group consisted of eight athletes and performed 3 days of weekly training intervention including 4 sets of 5 repetitions of 5 seconds of all-out running for sSIT program and also back squats, leg presses, seated knee flexions, and calf raises for 3 sets of 6-12 repetition maximum for the RT intervention. After the intervention, the sSIT, RT, sSIT + RT and RT + sSIT groups demonstrated improvements in the countermovement vertical jump (CMVJ) (effect size [ES] = 0.64, 0.88, 1.58, 1.55), 20-m sprint (ES = -0.82, -0.62, -1.10, -1.16), 4 × 9-m shuttle run (ES = -0.62, -0.35, -1.15, -0.89), strength (ES = 0.19, 0.44, 0.34, 0.43), peak (ES = 1.27, 0.73, 1.80, 1.53), and mean power output (ES = 0.87, 0.54, 1.37, 1.11), as well as in comparison to the CG (p < 0.05), respectively. Additionally, improvements in aerobic performance were observed in the sSIT, sSIT + RT, and RT + sSIT groups (ES = 0.75, 0.92, 0.62) after the training intervention, and in comparison to CG (p < 0.05), while the RT group did not show significant changes post-training. By comparing the CT groups, no sequencing effects were observed in the adaptations of variables between the sSIT + RT vs. RT + sSIT groups. In conclusion, this study's findings demonstrate that sSIT, RT, and CT with different orders have a positive impact on inducing adaptations in physical fitness, aerobic and anaerobic performance. Additionally, combining sSIT and RT resulted in further adaptations in karate athletes without any differences between CT groups.

Exercise training requires the careful application of training dose to maximize adaptation while minimizing the risk of illness and injury. High-intensity interval training (HIIT) is a potent method for improving health and fitness but generates substantial autonomic imbalance. Assuming a supine posture between intervals is a novel strategy that could enhance physiological readiness and training adaptations. This study aimed to establish the safety and feasibility of supine recovery within a HIIT session and explore its acute effects.

Fifteen healthy, active males (18-34 years) underwent assessment of cardiopulmonary fitness. Participants completed two identical HIIT treadmill sessions (4 x [3 min at 95% VO2max, 3 min recovery]) employing passive recovery in standing (STANDard) or supine (SUPER) posture between intervals. Heart rate variability (HRV), HRV recovery (HRVrec; lnRMSSD) and heart rate recovery at 1 min (HRrec) were assessed using submaximal constant speed running tests (CST) completed prior to, immediately after and 24 h following HIIT.

No severe adverse events occurred with SUPER, and compliance was similar between conditions (100 ± 0%). The change in HRVrec from the CST pre-to-post-HIIT was not different between conditions (p = 0.38); however, HRrec was faster following SUPER (39 ± 7 bpm) vs. STANDard (36 ± 5 bpm). HRV 24 h post-SUPER was also greater (3.56 ± 0.57 ms) compared to STANDard (3.37 ± 0.42 ms). Despite no differences in perceived exertion (p = 0.23) and blood lactate levels (p = 0.35) between SUPER and STANDard, average running HRs were lower (p = 0.04) with SUPER (174 ± 7 bpm) vs. STANDard (176 ± 7 bpm).

Supine recovery within HIIT attenuates acute cardioautonomic perturbation and accelerates post-exercise vagal reactivation. SUPER enhances recovery of vagal modulation, potentially improving physiological preparedness 24 h post-HIIT. Further research exploring the chronic effects of SUPER are now warranted.

Soccer is an intermittent team sport that demands high aerobic capacity. On field, soccer players' aerobic capacity, assessed through the maximal oxygen uptake (VO2max), is usually determined by an intermittent recovery test. The aim of this study was to obtain a construct validity of a new intermittent recovery test (IRT) with a fixed speed and a progressive decrement of rest period.

Twenty-five male soccer players were recruited to perform an incremental continuous test (ICT) and the new IRT, to compare their physiological data. Fifteen male soccer players were involved to perform a test-retest of IRT to assess its reliability.

VEpeak, absolute VO2max, relative VO2max and VCO2peak registered during ICT and IRT correlated strongly (Pearson's correlation coefficient ranges from 0.75 to 0.80, with very large as magnitude of effects and with P<0.001). IRT showed reliability from good to excellent regarding VEpeak, absolute VO2max, relative VO2max, VCO2peak and covered distance (ICC values ranged from 0.82 to 0.95).

These findings and its underlying physiological and muscular demands, suggest that IRT can be considered as a valid and reliable test to assess aerobic capacity in soccer players during the competitive period.

This review aims to evaluate the effectiveness of HIIT on basketball players' physical fitness and skill-related performance. This study adhered to the PRISMA guidelines and included randomized controlled trials (RCTs) that investigated the effects of HIIT on basketball players. The databases searched included Web of Science, Scopus, PubMed, and SPORTDiscus (up to 4 March 2024). The meta-analysis used a random-effects model, with effect sizes (ES) calculated for various performance outcomes. A total of 15 studies, with a low risk of bias or some concerns of bias, including 369 players (130 females, 239 males) at the developmental level, national level, and international level, were included in the systematic review, with 7 of these included in the meta-analysis. The systematic review indicated that HIIT significantly improved cardiovascular endurance, power, change of direction (COD) ability, linear sprint, and basketball skill-related performance. However, the effects on certain physical aspects such as VO2max, the Yo-Yo intermittent recovery test level 1 (Yo-Yo IR 1), jump tests, ball throw test, 20-m COD sprint test, T-test, 20-m linear sprint, and basketball-specific skills such as shooting accuracy and passing were inconsistent. The meta-analysis revealed a very large effect on the Yo-Yo IR 1 (ES = 2.32; p = 0.000), a moderate effect on VO2max (ES = 0.90; p = 0.000), T-test performance (ES = 0.91; p = 0.000), and CMJ height (ES = 0.76; p = 0.000), and a small effect on the 20-m sprint test (ES = 0.59; p = 0.006). HIIT appears to be an effective training method for improving general physical fitness and certain basketball-specific skills, particularly endurance, power, and agility. However, its impact on more skill-specific aspects, such as shooting accuracy and passing, requires further investigation. Coaches should consider supplementing HIIT with targeted skill training and carefully plan its timing, ideally incorporating HIIT during pre-season or off-season periods for optimal effectiveness. Further research is needed to explore the differential effects of HIIT across various age groups and playing levels.

High-intensity interval training (HIIT) performed before, during, and after cancer treatment can attenuate the adverse effects induced by anti-cancer drugs. A clear presentation and rationale of characteristics of HIIT variables is vital to produce the expected HIIT adaptations in cancer patients. However, there are concerns regarding the HIIT protocols used in the cancer literature.

The aims were to (1) identify the characteristics of HIIT and the formats that have been prescribed, (2) analyze which anchors have been utilized to prescribe effort and pause intensity, (3) examine characteristics of the physical tests used for HIIT prescription, and (4) identify potential adverse events related to HIIT intervention.

This scoping review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines, including PubMed, Scopus, and Web of Science databases.

A total of 51 studies were retrieved, and the following results were found: (1) Only 25 studies reported all four essential variables for HIIT prescription [effort intensity (effort duration): pause intensity (pause duration)]. Of these studies, 23 used active pause and employed the following prescription (on average): [84% (116 s): 39% (118 s)] when percentage of maximal aerobic power (MAP) [maximal/peak oxygen uptake ( V O2max/peak)/MAP] was used; [124% (161 s): 55% (142 s)] when percentage of anaerobic threshold (AT) was used; [83% (230 s): 62% (165 s)] when maximal heart rate percentage (%HRmax) was used. From these 23 studies, 12 used V O2max/peak/MAP (one of the most recommended variables for HIIT prescription). Seven studies adopted the HIIT-long format, and in the remaining five studies, the format was unclear. (2) Twenty-four studies used fractions of V O2max/peak or mechanical variables like MAP as anchors for prescribing effort intensity, two studies used AT, 20 studies used fractions of HRmax/heart rate reserve, two studies used rate of perceived exertion (RPE), while one used RPE and % V O2peak concomitantly, and two studies utilized RPE/%HRmax concomitantly. Two studies utilized passive resting, 12 studies used % V O2peak/%MAP for prescribing pause intensity, four studies used AT, seven studies used %HRmax, one study used %HRmax/% V O2peak, and two studies used absolute loads. (3) Ten studies did not report the characteristics of the physical tests employed, two studies used submaximal tests, and 39 studies utilized graded exercise tests. (4) Ten studies did not report if there were adverse events associated with the exercise program, while 34 studies did not report any adverse events.

Only 50% of the studies provided all the necessary variables for accurate HIIT prescription, raising concerns about the replicability, comprehension, and effective application of HIIT in cancer patients. Most of the studies that reported all variables appeared to have employed the HIIT-long format. Only a few studies used more individualized anchors (e.g., AT) to prescribe HIIT-long format for cancer patients, which is considered a very heterogeneous population.

To systematically and broadly review the literature to show the available information on high-intensity interval training for kidney transplant recipients as an adjunct to physical rehabilitation.

A scoping review of high-intensity interval training for post-kidney transplant patients was conducted by searching the PubMed, EMBASE (Elsevier), Scopus (Elsevier), Web of Science, and PEDro databases. Full-text records on the subject were included. Articles not published in English were excluded. The selected articles went through careful production quality analysis using the PEDro scale.

The search identified 26 articles, 3 of which met the inclusion criteria. The material demonstrated satisfaction, confidence, improvement in resting heart rate, and absence of adverse effects from high-intensity interval training for kidney transplant recipients.

Based on this scoping review, high-intensity interval training for kidney transplant patients may be beneficial for physical and mental aspects and complement physical rehabilitation programmes, but there is a need for more studies with robust samples and long-term follow-up to confirm these benefits.

This study primarily investigates the impact of a 6-week Sprint Interval Training (SIT) intervention on the physical fitness test results of male university students, as well as the dose-response relationship in adjusting the experimental protocol.

A total of 26 male university students (aged 20 ± 2 years; height 174 ± 7 cm; weight 70 ± 14 kg; mean ± SD) with no systematic training in the past 3 months, no physiological diseases, and healthy physical condition voluntarily participated in the experiment. The SIT protocol was designed based on a classic Wingate sprint protocol (4-6 x 30 s sprints with 4 m of recovery), and adjustments were made based on the participants' actual adaptation. The final intervention consisted of 6 weeks of training, three times per week, with 2-3 repetitions of 30-s Wingate sprints (Cd = 0.075, resistance on the ergometer = weight/kg x Cd) and 4-5 m of recovery.

The results showed significant improvements in key anaerobic capacity indicators after the 6-week intervention: Average Power (AP) increased from 77.4 ± 10.1 to 132.6 ± 21.1 (p < 0.01, Adjusted p < 0.03 ment, with a maximum effect size of 3.344), Peak Power (PP) increased from 102.9 ± 14.5 to 189.5 ± 28.8 (p < 0.01, Adjusted p < 0.02, maximum effect 3.790), and Time to Peak Power (TTP) decreased from 12.3 ± 3.3 to 9.5 ± 2.6 (p < 0.01), confirming that the intervention enhanced the participants' anaerobic capacity. Additionally, The results of the physical fitness test showed significant improvements: standing long jump (SLJ) increased from 2.31 ± 0.15 m to 2.45 ± 0.18 m (significance level p < 0.01), 50 m sprint time decreased from 7.32 ± 0.42 s to 6.98 ± 0.38 s (significance level p < 0.01), and 1,000 m from 235.6 ± 18.4 s to 220.3 ± 16.8 s (significance level p < 0.01). Other metrics such as Body mass, BMI, Vital capacity, and Pull-ups also showed minor increases. Interestingly, Sit forward in a sitting position scores showed a noticeable improvement (from 12.9 ± 6.8 to 15.8 ± 6.2, p = 0.091).

Furthermore, The adjustment of the training programme has achieved good results, as evidenced by the fact that participants have achieved a training completion rate of over 95%, maintained a moderate subjective fatigue rating (RPE score of 13-15), and no one has withdrawn from the training due to discomfort.

The modified SIT protocol proves to be an efficient and practical training method for improving college students' physical fitness.

While the literature provides evidence supporting the effectiveness of evening sprint interval training (SIT), there remains a limited amount of research investigating the effects of morning SIT among soccer athletes. This study examined the effects of morning versus evening SIT during the preparatory phase on physical and physiological performance in collegiate soccer players. Thirty male players volunteered to participate in the study and were randomly divided into morning, evening, or control groups, each group consisting of 10 subjects. The evaluation of physical (countermovement vertical jump [CMVJ], 20-m sprint, Illinois change of direction, and Yo-Yo intermittent recovery test level 1 [Yo-Yo IR1]) and physiological (graded exercise test and Wingate anaerobic power test) performance took place prior to and following the 7-week SIT, both in the morning and evening testing sessions. Both training groups showed significant improvements in physical and physiological performance from pre- to post-training, regardless of testing session timing (p < 0.05). The morning SIT group exhibited greater adaptive changes (p < 0.05) compared to the evening SIT group in CMVJ, 20-m sprint, Yo-Yo IR1, peak and mean power outputs at both the morning and evening testing sessions. These findings suggest that male soccer players can benefit from both morning and evening SIT sessions; however, conducting SIT in the morning could result in greater adaptive changes than evening training. To optimize physical performance adaptations, coaches should schedule SIT sessions in the morning. It is recommended to schedule conditioning workouts in the morning and team practices in the afternoon for optimal adaptations.

We aimed to determine: (a) the chronic effects of interval training (IT) combined with blood flow restriction (BFR) on physiological adaptations (aerobic/anaerobic capacity and muscle responses) and performance enhancement (endurance and sprints), and (b) the influence of participant characteristics and intervention protocols on these effects.

Searches were conducted in PubMed, Web of Science (Core Collection), Cochrane Library (Embase, ClinicalTrials.gov, and International Clinical Trials Registry Platform), and Chinese National Knowledge Infrastructure on April 2, with updates on October 17, 2024. Pooled effects for each outcome were summarized using Hedge's g (g) through meta-analysis-based random effects models, and subgroup and regression analyses were used to explore moderators.

A total of 24 studies with 621 participants were included. IT combined with BFR (IT+BFR) significantly improved maximal oxygen uptake (VO2max) (g = 0.63, I2 = 63%), mean power during the Wingate 30-s test (g = 0.70, I2 = 47%), muscle strength (g = 0.88, I2 = 64%), muscle endurance (g = 0.43, I2 = 0%), time to fatigue (g = 1.26, I2 = 86%), and maximal aerobic speed (g = 0.74, I2 = 0%) compared to IT alone. Subgroup analysis indicated that participant characteristics including training status, IT intensity, and IT modes significantly moderated VO2max (subgroup differences: p < 0.05). Specifically, IT+BFR showed significantly superior improvements in VO2max compared to IT alone in trained individuals (g = 0.76) at supra-maximal intensity (g = 1.29) and moderate intensity (g = 1.08) as well as in walking (g = 1.64) and running (g = 0.63) modes. Meta-regression analysis showed cuff width (β = 0.14) was significantly associated with VO2max change, identifying 8.23 cm as the minimum threshold required for significant improvement. Subgroup analyses regarding muscle strength did not reveal any significant moderators.

IT+BFR enhances physiological adaptations and optimizes aspects of endurance performance, with moderators including training status, IT protocol (intensity, mode, and type), and cuff width. This intervention addresses various IT-related challenges and provides tailored protocols and benefits for diverse populations.

Standard lifestyle interventions have shown limited efficacy in preventing type 2 diabetes among individuals with isolated impaired fasting glucose (i-IFG). Hence, tailored intervention approaches are necessary for this high-risk group.

This study aims to (1) assess the feasibility of conducting a high-intensity interval training (HIIT) study and the intervention acceptability among individuals with i-IFG, and (2) investigate the preliminary efficacy of HIIT in reducing fasting plasma glucose levels and addressing the underlying pathophysiology of i-IFG.

This study is a 1:1 proof-of-concept randomized controlled trial involving 34 physically inactive individuals (aged 35-65 years) who are overweight or obese and have i-IFG. Individuals will undergo a 3-step screening procedure to determine their eligibility: step 1 involves obtaining clinical information from electronic health records, step 2 consists of completing questionnaires, and step 3 includes blood tests. All participants will be fitted with continuous glucose monitoring devices for approximately 80 days, including 10 days prior to the intervention, the 8-week intervention period, and 10 days following the intervention. Intervention participants will engage in supervised HIIT sessions using stationary "spin" cycle ergometers in groups of 5 or fewer. The intervention will take place 3 times a week for 8 weeks at the Aerobic Exercise Laboratory in the Rehabilitation Hospital at Emory University. Control participants will be instructed to refrain from engaging in intense physical activities during the study period. All participants will receive instructions to maintain a eucaloric diet throughout the study. Baseline and 8-week assessments will include measurements of weight, blood pressure, body composition, waist and hip circumferences, as well as levels of fasting plasma glucose, 2-hour plasma glucose, and fasting insulin. Primary outcomes include feasibility parameters, intervention acceptability, and participants' experiences, perceptions, and satisfaction with the HIIT intervention, as well as facilitators and barriers to participation. Secondary outcomes comprise between-group differences in changes in clinical measures and continuous glucose monitoring metrics from baseline to 8 weeks. Quantitative data analysis will include descriptive statistics, correlation, and regression analyses. Qualitative data will be analyzed using framework-driven and thematic analyses.

Recruitment for the study is scheduled to begin in February 2025, with follow-up expected to be completed by the end of September 2025. We plan to publish the study findings by the end of 2025.

The study findings are expected to guide the design and execution of an adequately powered randomized controlled trial for evaluating HIIT efficacy in preventing type 2 diabetes among individuals with i-IFG.

Clinicaltrials.gov NCT06143345; https://clinicaltrials.gov/study/NCT06143345.

PRR1-10.2196/59842.

The benefits of exercise have been well described for the treatment of hypertension. Poor reporting quality impairs quality appraisal and replicability. High intensity interval training (HIIT) has been shown to be an effective alternative to traditional aerobic exercise in patients with hypertension. We evaluated the completeness of reporting of randomized controlled trials (RCTs) with HIIT for hypertension and to compare both exercise modes in reporting quality. RCTs of HIIT with a minimum duration of 6 weeks in adults with at least high normal blood pressure (≥130 mmHg/≥85 mmHg) were evaluated using the Consensus on Exercise Reporting Template (CERT). Nine RCTs conducting HIIT in hypertensive patients (N=718; 51.8 years) were evaluated. A mean of 62.6% of items were sufficiently described, compared with 49.2% in moderate intensity training interventions. Exercise dose was adequately reported in 8 out of 9 studies. Only one study reported information on adverse events. In a small sample of RCTs with HIIT in patients with hypertension we found a better reporting quality than in moderate intensity training interventions. However, reporting completeness is not optimal for a good replicability in clinical practice. The lack of reporting of adverse events in interventions using high intensities is particularly unfavourable.

To investigate the acute effects of hypoxia applied during discrete work and recovery phases of a perceptually regulated, high-intensity interval exercise (HIIE) on external and internal loads in inactive overweight individuals. On separate days, 18 inactive overweight (28.7 ± 3.3 kg m-2; 31 ± 8 years) men and women completed a cycling HIIE protocol (6 × 1 min intervals with 4 min active recovery, maintaining a perceived rating of exertion of 16 and 10 during work and recovery, respectively, on the 6-20 Borg scale) in randomized conditions: normoxia (NN), normobaric hypoxia (inspired O2 fraction ∼0.14) during both work and recovery (HH), hypoxia during recovery (NH) and hypoxia during work only (HN). Markers of external (relative mean power output, MPO) and internal load (blood lactate concentration, heart rate and tissue saturation index (TSI)) were measured. MPO was lower in HH compared to NN, NH and HN (all P < 0.001), with HN also being lower than NN (P < 0.001) and NH (P < 0.023). Heart rate was higher in HN than NN, HH and NH (all P < 0.001). Blood lactate response was higher in NN than HH (P = 0.003) and NH (P = 0.008). Changes in the TSI area above the curve were greater in HN relative to NN, HH and NH (all P < 0.001). Hypoxia applied intermittently during the work or recovery phases may mitigate the declines in mechanical output observed when exercise is performed in continuous hypoxia, although hypoxia implemented during the work phase resulted in elevated heart rate and lactate response. Specifically, exercise performance largely comparable to that in normoxia can be achieved when hypoxia is implemented exclusively during recovery.

Higher work rates may be sustainable when maintaining target rating of perceived exertion (RPE) compared to maintaining target heart rate (THR) during high-intensity interval training (HIIT) exercise in hot conditions, but may also result in greater thermal strain and cardiovascular drift, as well as greater decrements in maximal oxygen uptake (V ˙ O2max).

To test the hypotheses that maintaining target RPE compared to THR during HIIT in the heat results in 1) smaller work rate adjustments, 2) greater thermal and cardiovascular strain, and 3) larger decreases inV ˙ O2max.

Eight adults (4 women) completed a graded exercise test on a cycle ergometer in 22°C and then 4 cycling trials in 35°C, consisting of an 8-min warm-up at 70% maximal heart rate (HRmax) or 12 RPE followed by 1 (15HR and 15RPE) or 5 (43HR and 43RPE) rounds of HIIT (1 round = 4 min work at 90% HRmax or 17 RPE and 3 min recovery at 70% HRmax or 12 RPE) totaling 15 min or 43 min of exercise, respectively. Each trial ended with a GXT to measureV ˙ O2max.

In the 43-min trials work rate decreased from the first to the fifth work interval in both conditions, but by a non-significant, yet moderately larger (ES = 0.53) amount during 43HR (46 ± 29 W) compared to 43RPE (30 ± 28 W). From the first to fifth work interval HR increased over time by 12 b⋅min-1 in 43RPE (p < 0.001), but did not increase during 43HR (p = 0.36). Rectal temperature increases were not different between conditions (43HR = 0.7°C, p < 0.001; 43RPE = 0.8°C, p < 0.001).V ˙ O2max decreased 15.6% (ES = 0.41) between 15RPE and 43RPE (p = 0.005), but it was not different over time during the HR-based trials [6.5%, ES = 0.16 (α adjusted for multiple comparisons = 0.0125) p = 0.03].

Maintaining target RPE and THR require considerable declines in work rate during HIIT in the heat, with ∼53% larger declines needed to maintain THR. The mitigation of cardiovascular drift in the THR trial may have contributed to the preservation ofV ˙ O2max.

This study aimed to compare the effects of sprint interval training versus traditional training on running performance in well-trained male distance runners.

Twenty male distance runners (VO2: 67.4 ± 4.5 mL/kg/min, personal best time for the 5000 m: 14'38″47 ± 00'23″46) were recruited and randomly assigned to either the intervention training (IT) group, which performed sprint interval training, or the control training (CT) group, which engaged in traditional long-distance training. Both groups completed their respective training regimens twice a week for 6 weeks. Measurements for VO2max, O2 cost, time to exhaustion (TTE), and running times for 100, 400, and 3000 m were taken before and after the intervention.

The results indicated that the IT group showed significant improvements in TTE and running performance across 100, 400, and 3000 m (all P < 0.01), while the CT group only demonstrated improvements in 400 m time (P < 0.01). The IT group exhibited superior 3000 m performance compared to the CT group (P < 0.01). Analysis of effect sizes revealed small to moderate improvements in physiological and performance measures for the IT group, with VO2max showing a small effect size of 0.43, O2 cost a moderate effect size of 0.65, and TTE a moderate effect size of 0.77.

These findings suggest that sprint interval training may offer superior benefits for enhancing running performance of well-trained male distance runners, particularly in time to exhaustion and middle-to long-distance events, compared to traditional longdistance training.

Acute caffeine ingestion can improve exercise performance. Interplay between caffeine habituation and training status on the performance-enhancing effect of caffeine is unknown.

Habitual caffeine consumption and training status affect the ergogenicity of pre-exercise caffeine intake on exercise performance.

Double-blind, placebo-controlled, counterbalanced experimental design.

Level 3.

Eighty physically inactive men were randomized into 1 of 4 groups: caffeine supplementation (CAF), caffeine supplementation + exercise training (CAFEXE), placebo (PLA), and placebo + exercise training (PLAEXE); high-intensity interval training and caffeine were administered for 9 and 8 weeks, respectively. Data were collected pre-test, mid-test, post-test, and delayed post-test, each including 2 experiment sessions (3 mg/kg caffeine or placebo), with an additional experiment session post-test (6 mg/kg caffeine). In each experiment session, 45-min after consuming a placebo or caffeine, a 3-km running test and a Wingate power test were performed.

Pre-exercise ingestion of 3 mg/kg caffeine improved 3-km running time and mean power output (MPO) in all groups at all stages (P < 0.05); this effect was higher in trained than in untrained volunteers (P < 0.05). Habitual caffeine consumption reduced the ergogenic effect of caffeine in both aerobic and anaerobic trials (P < 0.05); 6 mg/kg caffeine enhanced this decrease only in CAFEXE (P < 0.05). Short-term caffeine withdrawal augmented the reduced ergogenic effect of caffeine on 3-km running performance and MPO in CAF and CAFEXE (P < 0.05).

Habituation to caffeine and training status could partially influence the ergogenic effects of caffeine on exercise performance.

Regular caffeine consumption leads to some degree of tolerance and decreases its ergogenicity. A pre-exercise increase in caffeine dosage in trained people and short-term caffeine withdrawal in both trained and untrained people could compensate for the reduced caffeine ergogenicity in young men.

Rating of perceived exertion (RPE) is a convenient and cost-effective tool that can be used to monitor high-intensity interval exercise (HIIE). However, no methodological study has demonstrated the validity of RPE in this context. Therefore, the aim of this study was to validate and calibrate RPE for monitoring HIIE in adolescents.

RPE, heart rate (HR), and oxygen uptake (V˙O2) data were retrospectively extracted from 3 lab-based crossover studies, with a pooled sample size of 45 adolescents, performing either cycling-based or running-based HIIE sessions. Within-participant correlations were calculated for RPE-HR and RPE-V˙O2, and receiver operator characteristic curve analysis was used to establish RPE cut points.

The results showed that RPE-HR demonstrated acceptable criterion validity (r = .53-.74, P < .01), while RPE-V˙O2 had poor validity (r = .40-.48, P < .01), except for HIIE at 100% peak power (r = .59, P < .01). RPE cut points of 4 and 5 were established in corresponding to HR/V˙O2 based thresholds.

RPE has some utility in evaluating intensity during lab-based running or cycling HIIE in adolescents. Future studies should expand the validation and calibration of RPE for prescribing and monitoring HIIE in children and adolescents in field-based contexts.

Obesity can change the immune microenvironment of adipose tissue and induce inflammation. This study is dedicated to exploring the internal mechanism by which different intensities of exercise reprogram the immune microenvironment of epididymal adipose tissue in nutritionally obese mice. C57BL/6J male obese mouse models were constructed by high-fat diet, which were respectively obese control group (OC), moderate-intensity continuous exercise group (HF-M), high-intensity continuous exercise group (HF-H), and high-intensity intermittent exercise group (HF-T). The exercise group was subjected to aerobic exercise intervention for 8 wk, and samples of mice were collected at the fourth and eighth week, respectively. Mice blood, liver, and adipose tissue of the epididymis were collected for index detection and adipose tissue ordinary transcriptome sequencing. After exercise intervention, when compared with the OC group, the morphology and blood indexes of the exercise groups were significantly improved. The liver lipid content was decreased, adipose tissue inflammation was reduced, and the mRNA and protein expression levels of IL-1β, F4/80, and CD64 in adipose tissue were significantly decreased (P < 0.01). Among the three exercise groups, the effect of the HF-T group was more significant. When compared with the OC group, fibroblast-specific marker genes, neutrophil marker genes, macrophage marker genes, and immune-related signaling pathways were significantly downregulated in the HF-T group. Exercise can reshape the immune microenvironment of adipose tissue, and high-intensity intermittent aerobic exercise is the most effective.NEW & NOTEWORTHY The present study has revealed that obesity is capable of altering the immune microenvironment within adipose tissue, thereby giving rise to inflammation. It has been demonstrated that exercise holds the potential to reverse the onset of inflammatory responses, with high-intensity intermittent aerobic exercise emerging as the most efficacious approach.

Sleep disturbances are common in individuals with posttraumatic stress disorder. Exercise interventions are a promising approach in the treatment of sleep disorders, but little is known about the efficacy of exercise interventions for sleep disturbances associated with posttraumatic stress disorder. A total of 40 individuals with posttraumatic stress disorder were randomized to six sessions of either high-intensity interval training or low-to-moderate-intensity training, administered within 12 days. Sleep quality was assessed over 24 days from baseline to post with the Pittsburgh Sleep Quality Index, a sleep log, and a waist-worn actigraphy. Analyses revealed that, regardless of group allocation, Pittsburgh Sleep Quality Index score improved significantly by 2.28 points for high-intensity interval training and 1.70 points for low-to-moderate-intensity training (d = 0.56 for high-intensity interval training; 0.49 for low-to-moderate-intensity training) over time, while there were no significant changes in any sleep log or actigraphy measure. Analysis of a subsample of those affected by clinically significant sleep disturbances (n = 24) revealed a significant time effect with no difference between exercise interventions: Pittsburgh Sleep Quality Index improved significantly by 2.65 points for high-intensity interval training and 2.89 points for low-to-moderate-intensity training (d = 0.53 for high-intensity interval training; 0.88 for low-to-moderate-intensity training), and actigraphy measure of wake after sleep onset was reduced significantly by 14.39 minutes for high-intensity interval training and 6.96 minutes for low-to-moderate-intensity training (d = 0.47 for high-intensity interval training; 0.11 for low-to-moderate-intensity training) from baseline to post. In our pilot study, we found an improvement in sleep quality from pre- to post-assessment. There were no significant differences between exercise groups. Further studies are needed to investigate whether the found time effects reflect the exercise intervention or unrelated factors.