Just HIT it! A time-efficient exercise strategy to improve muscle insulin sensitivity
Martin J. Gibala and Jonathan P. Little
Public health guidelines generally recommend adults perform at least 150 minutes of “moderate-intensity aerobic physical activity (40-60% of VO2 max) per week or a minimum of 60 minutes of “vigorous-intensity” exercise (>60% VO2 max) per week to promote health.
Unfortunately, most people fail to meet the minimum physical activity guidelines, citing “lack of time” as the major barrier.
A growing body of evidence suggests that high-intensity interval training (HIT) induces numerous physiological adaptations that are similar to endurance training despite a lower total exercise volume and training time commitment.
A common model used for HIT is the Wingate test, which consists of :30 all-out cycling effort against a standard resistance: 4 to 6 x :30 effort with a 4 minute recovery, equaling only 2 to 3 minutes of actual work time spread over a 15 to 30 minute period.
In a recent issue of the Journal of Physiology, Richards, et. al. (2010) report a Wingate-based HIT protocol consisting of only 16 minutes of all-out cycling over 14 days improved insulin sensitivity in previously sedentary or recreationally active young adults.
A modified Wingate protocol involved 8 to 12 x 1:00 intervals performed at 100% VO2 max with a 1:15 recovery time – 8 to 12 minutes of total exercise time spread over a 17 to 25 minute period. This was done for six sessions over 2 weeks and was a sufficient stimulus to increase skeletal muscle oxidative capacity and GLUT4 protein content.