Isolated knee extension resistance training and functional outcomes in patients with heart failure: A narrative review

Table 1 Isolated knee extensor resistance training protocol for heart failure patients

Ref.	Subject	Intensity	Session duration	Frequency, duration of exercise
Jankowska et al[26], 2008	10 stable CHF patients (NYHA III) with LVEF 30% ± 5%	35% of maximum strength in the first week, increasing gradually to 60% in the 12th week	± 30 minutes/session: 10 minutes warm-up, 10-15 minutes KERT, 5-10 minutes cool-down	3 times per week; program duration 12 weeks (training phase) + 12 weeks detraining
Louis et al[48], 2024	70 CHF patients (NYHA I-III) who participated in cardiac rehabilitation	30% 1RM at the start of training, progressively increased by 5%-10% every 4 sessions as tolerated	30-45 minutes/session: 10-15 minutes warm-up, 15-20 minutes core training (lower-limb resistance with KERT emphasis), 10-15 minutes cool-down	2 times per week; program duration 12 weeks
Jónsdóttir et al[28], 2006	43 CHF patients (NYHA II-III)	0%-25% 1RM in the initial phase, increasing to 35%-40% 1RM at the end of the study (in some patients)	± 45 minutes/session: 10 minutes warm-up, ± 35 minutes KERT core training, 5 minutes cool-down	2 times per week; program duration 5 months
Esposito et al[10], 2011	6 stable male CHF patients (NYHA II-III, VO2 peak Weber class C/B, LVEF 25% ± 3%) and 6 healthy male controls	Intensity varies, progressively increased based on evaluation every 2 weeks during KERT	± 50 minutes/session per leg: Knee extension exercises, including light warm-up and stretching	3 times per week; program duration 8 weeks
Hearon et al[11], 2022	12 HFpEF patients (> 65 years, EF > 50%) + 9 healthy controls	Individual, progressive intensity; initial steady-state, then 8 minutes × 2 minutes and 4 minutes × 4 minutes intervals, kick rate 30-50 kicks/minute	± 30 minutes/session per leg (total ± 60 minutes/session)	3 times per week; program duration 8 weeks
Magnusson et al[31], 1996	Eleven patients with chronic CHF (9 men, 2 women), NYHA II-IV, LVEF 5%-39%, some with idiopathic DCM, some post-MI, stable for ≥ 3 months. Randomized to single-leg strength training or single-leg endurance training	Strength training: Single-leg KERT, 80% of maximum. Endurance training: 65%-75% of peak single-leg workload, using a modified ergometer	Strength training: 4 sets of 6-10 repetitions, 2 minutes rest, 3 seconds of up-and-down movement. Endurance training: 15 minutes of dynamic knee extensor exercises	3 times per week, duration 8 weeks
Gordon et al[34], 1996	20 patients with stable CHF (NYHA II-III), LVEF 27% ± 3%, aged 43-73 years	65% of pretraining PWL at baseline, increasing to 75%	± 15 minutes per session: Two-legged dynamic knee extensor	3 times per week; program duration 8 weeks
Gordon et al[33], 1997	21 patients with stable CHF (NYHA II-III), LVEF 28% ± 3%, aged 43-73 years	One-legged KERT: 35% of absolute peak two-legged workload; two-legged KERT: 65%-75%	± 15 minutes per session: Dynamic knee extensor	3 times per week; program duration 8 weeks
Laoutaris et al[27], 2013	Stable CHF patients (NYHA II-III) with LVEF ≤ 40%, CHF due to ischemic or dilated cardiomyopathy, hemodynamically stable for ≥ 3 months	AT: 70%-80% maximal HR. RT: Dynamic KERT 50% 1RM, and upper limb resistance exercises using dumbbells of 1-2 kg, progressively every 2 weeks. BMI: 60% SPImax	AT: 20 minutes during the first week, increased by a minimum of 1 minutes in each training session. Combined ARI: AT: 30 minutes; RT: 3 sets of 10-12 repetitions KERT, 2 sets of 10-12 repetitions elbow flexion, shoulder flexion, and abduction; BMI: 20 minutes. Warm up and cooldown: 5 minutes each	3 times per week; program duration 12 weeks
Tyni-Lenné et al[12], 1996	16 stable CHF patients (NYHA II-III) with LVEF < 40%	During the first 4 weeks, 65%, and during the last 4 weeks, 75% of the absolute baseline PWL, bilateral dynamic KERT on a knee extensor ergometer	60 repeats per minute for 15 minutes. Warm-up: 6 minutes of walking and stretching, and a cooldown of 3 minutes of walking and stretching	3 times per week; program duration 8 weeks
Tyni-Lenné et al[36], 1998	24 stable CHF patients (NYHA II-III), 12 males & 12 females, LVEF < 40%	65% baseline PWL (weeks 1-4), 75% (weeks 5-8)	± 15 minutes/knee-extensor session + 6 minutes warm-up and 3 minutes cool-down	3 times per week; program duration 8 weeks

CHF: Chronic heart failure; NYHA: New York Heart Association; LVEF: Left ventricular ejection fraction; HFpEF, Heart failure with preserved ejection fraction; EF: Ejection fraction; DCM: Dilated cardiomyopathy; MI: Myocardial infarction; RM: Repetition maximum; KERT: Knee extension resistance training; PWL: Peak work load; AT: Aerobic training; HR: Heart rate; RT: Resistance training; BMI: Body mass index; SPImax: Sustained maximal inspiratory pressure; VO₂ peak: Peak oxygen uptake; ARI: Aerobic, resistance, and inspiratory muscle training.

Table 2 Description of effects of isolated knee extension resistance training on functioning in patients with heart failure

Ref.	Types of exercise	Effects on symptoms	Muscle fitness	Cardiorespiratory fitness	Health-related quality of life
Jankowska et al[26], 2008	KERT	Improvement in NYHA clinical status, some effects resolved after detraining	Quadriceps strength increased ± 37% right, ± 31% left	6MWT distance and total exercise time increased, but VO2 peak did not change	Increases after training, does not persist after detraining
Jónsdóttir et al[28], 2006	KERT	No significant NYHA changes	Quadriceps strength increased significantly	6MWT distance increased significantly, VO2 peak did not change	The exercise capacity subcategory increased significantly, total HRQoL was not significant
Gordon et al[34], 1996	One-legged and two-legged dynamic KERT	There was no significant change in symptoms	Peak workload on both legs increased significantly, and there was no significant increase on one leg	VO2 peak unchanged	Not reported
Gordon et al[33], 1997	Two-legged dynamic KERT	There was no significant change in symptoms	Quadriceps strength increased	VO2 peak unchanged	Training improved the quality of life
Magnusson et al[31], 1996	Strength training (KERT)/endurance training (one-leg dynamic KERT)	There was no significant change in symptoms	Strength: ± 40% increase in isometric and dynamic strength; Endurance: ± 24% increase in isometric strength	Maximal exercise capacity increased by 10%-18%, and VO2 peak remained unchanged	Not reported
Esposito et al[10], 2011	Single-legged KERT	No change in NYHA	Quadriceps strength increased by 15%	Leg VO2 peak increased to control levels	Not reported
Hearon et al[11], 2022	Isolated KERT	PWR increases, and blood pressure during exercise decreases	Not reported	Absolute and relative VO2 peak increased, along with an increase in a-vO2 difference	Not reported
Laoutaris et al[27], 2013	AT/RT/IMT	Improved functional capacity and clinical status	Quadriceps strength increased	VO2 peak increases	Significant increase
Tyni-Lenné et al[12], 1996	Bilateral dynamic KERT	No significant change in symptoms	PWR increased significantly	6MWT distance increased significantly	Significant increase
Tyni-Lenné et al[36], 1998	KERT	No significant change in symptoms	PWR increased significantly	6MWT distance increased significantly	Significant increase

KERT: Knee extension resistance training; AT: Aerobic training; RT: Resistance training; IMT: Inspiratory muscle training; NYHA: New York Heart Association; PWR: Peak work rate; 6MWT: Six-minute walk test; VO₂ peak: Peak oxygen uptake; a-vO₂: Arteriovenous oxygen; HRQoL: Health-related quality of life.