n International SportMed Journal - Metabolic responses to multiple bouts of supra-maximal exercise in trained and untrained subjects : research article

Volume 5, Issue 2
  • ISSN : 1528-3356



Performance and metabolic pathways used in submaximal exercise have been well examined, but not above VO.

To examine the pattern of energy use during supra-VOmaximal exercise, the metabolic responses of both trained and untrained subjects to repeated bouts of intense, constant power exercise, which was designed to deplete muscle glycogen, were evaluated.
Sixteen males with similar genetic aerobic capacity were studied: active but untrained (AUT), and exercise trained (TR). Subjects ran to exhaustion at 125% VO for 25 bouts (20 min. rest periods, water but no carbohydrate supplementation).
The results are presented as mean ± SD. Total exercise time was significantly greater in TR (42.75 ± 3.85 min) than AUT (33.10 ± 6.95 min). VOremained constant at 95% of maximum for 10 bouts in AUT and for 20 bouts in TR, after which VO dropped to 60-65% of maximum in AUT and to 85-90% of maximum in TR. During bouts 11-25, TR had significantly greater peak lactates (6.91±0.9 vs. 2.66±0.5 mM), greater VE/VO ratios (31 ± 2 vs. 25 ± 9) and greater rates of lactate accumulation (4.90±0.74 vs. 3.09±0.68 Mm.min-1) than AUT.
TR had significant glycolysis during all 25 exercise bouts, whereas AUT became glycogen-depleted. Trained subjects apparently spared glycogen during supra-VOmaximal exercise presumably by oxidising more fat (in slow twitch fibres). Thus athletes who participate in anaerobic events may benefit substantially from aerobic training, as well as anaerobic training.

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