Article #40 of 50: I have made it a goal of mine to share at least 50 research articles with you to review in 2012. These articles will be shared with no opinion of mine, just purely the information provided in the research and where to go to read more about the topic. This weekly challenge will feature many different aspects of the field: strength, conditioning, nutrition, psychology, etc. If you would like to submit research articles to be included in this segment, please email me a PDF version of the peer reviewed journal article.

Acta Physiol 2012, 205, 177–185.

Aim: As a consequence of enhanced local vascular conductance, perfusion of muscles increases with exercise intensity to suffice the oxygen demand. However, when maximal oxygen uptake (VO2max) and cardiac output are approached, the increase in conductance is blunted. Endurance training increases muscle metabolic capacity, but to what extent that affects the regulation of muscle vascular conductance during exercise is unknown.

Methods: Seven weeks of one-legged endurance training was carried out by twelve subjects. Pulmonary VO2 during cycling and one-legged cycling was tested before and after training, while VO2 of the trained leg (TL) and control leg (CL) during cycling was determined after training.

Results: VO2max for cycling was unaffected by training, although one-legged VO2max became 6.7 (2.3)% (mean +/- SE) larger with TL than with CL. Also TL citrate synthase activity was higher

[30 (12)%; P < 0.05]. With the two legs working at precisely the same power during cycling at high intensity (n = 8), leg oxygen uptake was 21 (8)% larger for TL than for CL (P < 0.05) with oxygen extraction being 3.5 (1.1)% higher (P < 0.05) and leg blood flow tended to be higher by 16.0 (7.0)% (P = 0.06). Conclusion: That enhanced VO2max for the trained leg had no implication for cycling VO2max supports that there is a central limitation to VO2max during whole-body exercise. However, the metabolic balance between the legs was changed during high-intensity exercise as oxygen delivery and oxygen extraction were higher in the trained leg, suggesting that endurance training ameliorates blunting of leg blood flow and oxygen uptake during whole-body exercise.

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