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June 24, 2005

Improve your performance in only 7 1/2 minutes a week

For endurance athletes, the two staple workouts are easy distance and interval training. If you want to get good, you've just got to put in the mileage. Or so we thought until recently. Eu-Jin Goh pointed me to this paper in the June Journal of Applied Physiology. The authors report significant improvement in endurance performance in untrained but active subjects with six sessions of sprint intervals totalling less than 15 minutes over two weeks:
Six sessions of sprint interval training increases muscle oxidative potential and cycle endurance capacity in humans

Kirsten A. Burgomaster,1 Scott C. Hughes,1 George J. F. Heigenhauser,2 Suzanne N. Bradwell,1 and Martin J. Gibala1

1Exercise Metabolism Research Group, Department of Kinesiology, and 2Department of Medicine, McMaster University, Hamilton, Ontario, Canada

Parra et al. (Acta Physiol. Scand 169: 157165, 2000) showed that 2 wk of daily sprint interval training (SIT) increased citrate synthase (CS) maximal activity but did not change "anaerobic" work capacity, possibly because of 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 (O2 peak), no study has examined the effect of SIT on "aerobic" exercise capacity. We tested the hypothesis that six sessions of SIT, performed over 2 wk with 12 days rest between sessions to promote recovery, would increase CS maximal activity and endurance capacity during cycling at ~80% O2 peak. Eight recreationally active subjects [age = 22 +/- 1 yr; O2 peak = 45 +/- 3 ml·kg1·min1 (mean +/- SE)] were studied before and 3 days after SIT. Each training session consisted of four to seven "all-out" 30-s Wingate tests with 4 min of recovery. After SIT, CS maximal activity increased by 38% (5.5 +/- 1.0 vs. 4.0 +/- 0.7 mmol·kg protein1·h1) and resting muscle glycogen content increased by 26% (614 +/- 39 vs. 489 +/- 57 mmol/kg 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 O2 peak. 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 wk apart without SIT. We conclude that short sprint interval training (~15 min of intense exercise over 2 wk) increased muscle oxidative potential and doubled endurance capacity during intense aerobic cycling in recreationally active individuals.

This is a very interesting result. A doubling of endurance is an amazing improvement. Two caveats: 1. 8 subjects in each group is really small. 2. This is in active but untrained athletes, so it's not clear that it will work for people who are trained. Nevertheless, as Kevin Dick observes, if reproducible this would be a great way for people to kick-start their training, getting themselves to the point where they can do longer workouts.

Posted by ekr at June 24, 2005 8:12 PM | Filed under: