Exercise after heart transplantation: An overview

Table 1 Summary of some of the observational studies describing the VO_2peak levels in heart transplant recipients

Study	n	Mean age (yr)	Mean time after HTx	VO2peak: mL/kg per minute or L/min	VO2peak (% of age-predicted value)	Percent of age-predicted HRmax or actual HRmax (bpm)
Renlund et al[123]	110	51 ± 10	26 mo	17.7 ± 0.3 mL	64% ± 1%	85%
Mandak et al[51]	60	52 ± 10	1 yr	16.2 ± 3.8 mL	NA	137 ± 24
Osada et al[124]	56	50 ± 12	3 yr	20.0 ± 5.0 mL	70% ± 17%	88% ± 11%
Notarius et al[12]	12	51 ± 4	8 mo	17.3 ± 1.7 mL	57%	147 ± 7
Douard et al[30]	85	52 ± 12	0-100 mo	21.1 ± 6 mL	NA	85% ± 13%
Squires et al[24]	95	48 ± 14	1 yr	19.9 ± 4.8 mL	61% ± 15%	138 ± 22
Gullestad et al[48]	174	51 ± 1	3.5 yr	19.4 ± 0.4 mL	70% ± 1%	146 ± 2
Myers et al[125]	47	47 ± 12	4.8 yr	9.4 ± 2.6 mL	59% ± 14%	129 ± 18
Schmid et al[126]	17	58 ± 13	65 ± 27	20.9 ± 5.2 mL	NA	136 ± 12
Richard et al[127]	7	40 ± 13	2 yr	NA	101% ± 12%	93% ± 9%
Carter et al[2]	47	48	5 yr	16.1 ± 0.5 mL	51% ± 1.5%	74% ± 1%
Ulubay et al[118]	7	43 ± 14	19 mo	1.45 ± 0.33 L	NA	114 ± 41

HTx: Heart transplant; HR_max: Maximum achieved heart rate; bpm: Beats per minute; NA: Not available.

Table 2 Possible mechanisms associated with reduced exercise capacity in heart transplant recipients

Central factors

Reduced cardiac output

Chronotropic incompetence

Reduced stroke volume

Systolic dysfunction

Diastolic dysfunction

Pulmonary dysfunction

Pulmonary hypertension

Lung disease

Pulmonary congestion

Peripheral factors

Decreased skeletal muscle function

Reduced muscle mass

Reduced muscle strength

Reduced capillary density

Reduced oxidative capacity

Reduced mitochondrial function

Corticosteroid induced myopathy

Impaired vasodilatory capacity

Endothelial dysfunction

Deconditioning

Potential factors contributing to reduced exercise capacity

Increasing age

Donor age

Donor match

Ischemic time

Pre transplant de-conditioning

Primary diagnosis

Co-morbidities

Smoking

Cultural differences

Gender differences

Anxiety and depression

Socio-economic status

Reduced health-related quality of life

Table 3 Summary of randomized controlled trials investigating the effect of exercise in heart transplant recipients

Study	n, mean age (yr)	Mean time after HTx	Intervention	Mean change in VO2peak (mL/kg per minute) within groups	Mean change in VO2peak (mL/kg per minute) between groups
Kobashigawa et al[3]	27, 52	1 mo	6 mo partly supervised rehabilitation program vs controls CG	Ex: 9.2 → 13.6	2.5
			Walking: cycling and upper and lower limb exercises for 30 min × 1-3/wk	Con: 10.4 → 12.3
Tegtbur et al[26]	32, 55	5 yr	1 yr home-based exercise program vs controls	Ex: 18.6 → 20.0	1.3
			Cycling every other day for 1 yr at 80%-90% of maximum HR	Con: 18.9 → 19.0
Bernardi et al[6]	24, 52	6 mo	6 mo home training vs controls	Ex: 14.9 → 19.6	3.4
			Cycling at 60%-70% of VO2peak 30 min × 5/wk × 6 mo	Con: 14.3 → 15.6
Karapolat et al[5]	28, 42	1.5 yr	8 wk supervised hospital training vs home-based training
			1.5 h of multiple exercises: including aerobic exercise for 30 min at 60%-70% of VO2peak× 3/wk	Ex: 16.7 → 19.5	3.4
			The controls received written guidelines on exercises and a walking program	Con: 20.1 → 19.5
Wu et al[27]	37, 56	2 yr	8 wk home training vs controls
			Strength training and aerobic exercise at 60%-70% of VO2peak: 35-40 min × 3/wk	Ex: 12.1 → 13.2	1.6
				Con: 13.7 → 13.2
Haykowsky et al[25]	43, 59	5 yr	12 wk aerobic/strength training vs controls
			First 8 wk: continuous aerobic exercise at 60%-80% of VO2peak: 30-45 min × 2/wk
			Continuous aerobic training at 80% of VO2peak, 45 min × 2/wk and bicycle interval training for 30 s at 90%-100% of VO2peak: followed by 60 s rest for 10-25 reps × 2/wk in the final 4 wk	Ex: 21.2 → 24.7	3.5
			Resistance training at 50% of 1RM: 10-15 reps × 1-2 sets × 4 exercises × 2/wk for 12 wk	Con: 18.2 → 18.2
Hermann et al[16]	27, 50	7 yr	8 wk high-intensity interval training vs controls
			Interval blocks of 4 min/2 min/30 s: corresponding to 80%: 85% and 90% of VO2peak: respectively: and recovery periods of ½ min: and finally staircase running at 80% of VO2peak: followed by recovery walking 60 min × 3/wk	Ex: 23.9 → 28.3	5.6
				Con: 24.6 → 23.4
Nytrøen et al[18]	48, 51	4 yr	1 yr high-intensity interval training vs controls
			4 interval blocks of 4 min each performed at 91% of peak HR: with 3 min active recovery periods between each block	Ex: 27.7 → 30.9	3.6
			3 periods of 8 wk distributed throughout 1 yr with exercise 3/wk for a total of 72 exercise sessions	Con: 28.5 → 28.0

HTx: Heart transplant; NT: No training; Ex: Exercise group; Con: Control group; 1RM: 1 repetition maximum; HR: Heart rate.