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

Maximal oxygen consumption (O) 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 O 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 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 O. We determined the DL-O 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-O increased by 13.8% ± 8.7 ( < 0.001) following the SL-ET, due to a larger maximal O systemic extraction; meanwhile, O in DL-ET increased by 18.6% ± 12.7 ( < 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 O and that the impaired peripheral O extraction and/or utilization play an important role in limiting O in these types of patients. SL-ET increases O in transplanted recipients because of improved peripheral O extraction and/or utilization. SL-ET is as successful as DL-ET to improve the cardiorespiratory fitness in transplanted recipients. The model of O limitation indicates the peripheral factors as a remarkable limitation to the O in these patients.