Effect of small vs large muscle mass endurance training on maximal oxygen uptake in organ transplanted recipients

Maximal oxygen consumption ((V)over dotO(2max)) is impaired in heart (HTx), kidney (KTx), and liver (LTx) transplanted recipients and the contribution of the cardiovascular, central, and peripheral (muscular) factors in affecting (V)over dotO(2max )improvement after endurance training (ET) has never been quantified in these patients. ET protocols involving single leg cycling (SL) elicit larger improvements of the peripheral factors affecting O-2 diffusion and utilization than the double leg (DL) cycling ET. Therefore, this study aimed to compare the effects of SL -ET vs DL-ET on (V)over dotO(2max). We determined the DL-(V)over dotO(2max )and maximal cardiac output before and after 24 SL-ET vs DL-ET sessions on 33 patients (HTx = 13, KTx =11 and LTx = 9). The DL-(V)over dotO(2max )increased by 13.8% +/- 8.7 (p < 0.001) following the SL-ET, due to a larger maximal O-2 systemic extraction; meanwhile, (V)over dotO(2max )in DL-ET increased by 18.6% +/- 12.7 (p < 0.001) because of concomitant central and peripheral adaptations. We speculate that in transplanted recipients, SL-ET is as effective as DL-ET to improve (V)over dotO(2max )and that the impaired peripheral O-2 extraction and/or utilization play an important role in limiting (V)over dotO(2max )in these types of patients. Novelty SL-ET increases (V)over dotO(2max) in transplanted recipients because of improved peripheral O-2 extraction and/or utilization. SL-ET is as successful as DL-ET to improve the cardiorespiratory fitness in transplanted recipients. The model of (V)over dotO(2max )limitation indicates the peripheral factors as a remarkable limitation to the (V)over dotO(2max )in these patients.

Automated summary

Endurance training, especially single leg cycling, can significantly improve maximal oxygen consumption in heart, kidney, and liver transplant recipients by enhancing peripheral oxygen extraction and utilization. Single leg cycling training is as effective as double leg cycling training in improving cardiorespiratory fitness in these patients. Peripheral factors play a significant role in limiting maximal oxygen consumption in transplant recipients.