title: One-legged endurance training: leg blood flow and oxygen extraction during cycling exercise.
abstract: OBJECTIVE
  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 (VO(2)max) 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 VO(2) during cycling and one-legged cycling was tested before and after training, while VO(2) of the trained leg (TL) and control leg (CL) during cycling was determined after training.
  
  
  RESULTS
  VO(2) max for cycling was unaffected by training, although one-legged VO(2) max 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).
  
  
  CONCLUSIONS
  That enhanced VO(2) max for the trained leg had no implication for cycling VO(2) max supports that there is a central limitation to VO(2) max 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.
authors: Norwegian School of Sport Sciences, Oslo, Norway. bjarne.rud@nih.no
authors: B
authors: B
authors: Rud
authors: O
authors: O
authors: Foss
authors: P
authors: P
authors: Krustrup
authors: N H
authors: NH
authors: Secher
authors: J
authors: J
authors: Hallén
mesh_terms: D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000378:metabolism; D000328:Adult; D002302:Cardiac Output / Q000502:physiology; D002950:Citrate (si)-Synthase / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply*; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000201:enzymology; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology*
chemical_list: D015094:3-Hydroxyacyl CoA Dehydrogenases; D002950:Citrate (si)-Synthase