ISSN:
1439-6327
Keywords:
Endurance exercise
;
Central vs peripheral adaptations
;
Muscle ultrastructure
;
Transfer effect
;
Bicycling
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary The effects of 8 weeks of bicycle endurance training (5 x /week for 30 min) on maximal oxygen uptake capacity ( $$\dot V_{O_{2max} } $$ ) during arm and leg ergometry, and on the ultrastructure of an untrained arm muscle (m. deltoideus), and a trained leg muscle (m. vastus lateralis) were studied. With the training, leg- $$\dot V_{O_{2max} } $$ for bicycling increased by +13%, while the capillary per fiber ratio and the volume density of mitochondria in m. vastus lateralis increased by +15% and +40%, respectively. In contrast, the untrained m. deltoideus showed an unchanged capillary per fiber ratio and a decreased mitochondrial volume density (−17%). Despite this decrease of mitochondrial volume arm- $$\dot V_{O_{2max} } $$ increased by +9%. It seems unlikely that the observed discrepancy can be explained by cardiovascular adaptations, since arm cranking did not fully tax the cardiovascular system (arm- $$\dot V_{O_{2max} } $$ /leg- $$\dot V_{O_{2max} } $$ : 0.74 and 0.71 before and after training, respectively). Thus neither cardiovascular adaptations nor local structural changes in the untrained muscles could explain the increased arm- $$\dot V_{O_{2max} } $$ . However, the enhanced capacity for lactate clearance after endurance training could be sufficient to account for the larger $$\dot V_{O_{2max} } $$ during arm cranking. We propose that an increased net oxidation of lactate might be responsible for the increased arm- $$\dot V_{O_{2max} } $$ found after bicycle endurance training.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02337178
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