In a recent study 16 young men performed 2 weeks of supervised high intensity training (HIT) comprising of a total of 15 min of exercise (6 sessions; 4–6 × 30-s cycle sprints per session). The subject performed about 250 kcal of work each week compared with the 2000 to 3000 kcal a week consumed during a typical aerobic training program. The results were surprising. Insulin sensitivity was improved by 23%, while aerobic cycling performance improved by ~6%. From the study Extremely short duration high intensity interval training substantially improves insulin action in young healthy males:
The efficacy of a high intensity exercise protocol, involving only ~250 kcal of work each week, to substantially improve insulin action in young sedentary subjects is remarkable.
The low volume, high intensity training utilized in the current study significantly reduced both glucose AUC (-12%) and insulin AUC (-37%), with a sustained improved insulin action until at least day three after the last exercise session. This very modest increase in calorie consumption is in stark contrast to the ~2000–3000 kcal•week-1 consumed during a typical aerobic training program. This implies, but does not prove, that the mechanism underpinning the benefits we observed with HIT, may be distinct from those responsible for the more modest improvements in insulin action with classic time-consuming aerobic training. While much focus is being given to increasing calorie consumption to ward off weight gain, it is clear that improving metabolic fitness may be just as important as limiting gains body mass index.
We have a client that confirms what this study suggests. He has lost fifty pounds in three years and has gone from three or four insulin shots down to one a day. He does high intensity strength training once a week and does regular aerobic activity.