Burgomaster KA, Hughes SC, Heigenhauser GJ, Bradwell SN, Gibala MJ
J Appl Physiol. 2005 Feb 10;
Parra et al. (Acta Physiol. Scand., 169:157-165, 2000) showed 2 wks of daily sprint interval training (SIT) increased citrate synthase (CS) maximal activity but did not change “anaerobic” work capacity, possibly due to chronic fatigue induced by daily training. The effect of fewer SIT sessions on muscle oxidative potential is unknown, and aside from changes in peak oxygen uptake (VO2peak), no study has examined the effect of SIT on “aerobic” exercise capacity. We tested the hypothesis that 6 sessions of SIT - performed over 2 wks with 1-2 d rest between sessions to promote recovery - would increase CS maximal activity and endurance capacity during cycling at ~80% VO2peak. Eight recreationally-active subjects [22+/-1 yr; VO2peak = 45+/-3 ml(.)kg-1(.)min-1 (mean+/-SE)] were studied before and 3 d after SIT. Each training session consisted of 4-7 “all out” 30-sec Wingate tests with 4 min recovery. Following SIT, CS maximal activity increased by 38% (5.5+/-1.0 vs 4.0+/-0.7 mmol(.)kg protein-1(.)hr-1) and resting muscle glycogen content increased by 26% (614+/-39 vs 489+/-57 mmol(.)kg-1 dry wt) (both P<0.05). Most strikingly, cycle endurance capacity increased by 100% after SIT (51+/-11 vs 26+/-5 min, P<0.05), despite no change in VO2peak. The coefficient of variation for the cycle test was 12.0% and a control group (n=8) showed no change in performance when tested ~2 wks apart without SIT. We conclude that short sprint interval training (~15 min of intense exercise over 2 wks) increased muscle oxidative potential and doubled endurance capacity during intense aerobic cycling in recreationally active individuals.
