Short-term exercise has a significant impact on insulin action in overweight people

Carefully controlling the amount of food and drink that formerly sedentary, overweight people ingest during and after short-term exercise has a significant impact on insulin action.

The same study showed a measurable affect on the subjects’ cardiovascular disease (CVD) risk factors, according to researchers in the Exercise Science Department at the University of Massachusetts, Amherst.

After only six days of enough treadmill exercise to burn 500 kilocalories (k/cal) each day, the eight subjects in the negative energy balance (NEG) group, who received no energy replacement, showed a significant (p=0.037) 40% increase in insulin action (measured by glucose rate of disappearance/steady state insulin). However insulin action was unchanged in the zero energy balance group (ZERO), who were required to finish a sports drink during exercise and additional food afterward to “replace” the 500 k/cal.

The same subjects showed positive trends in both traditional and novel CVD risk factors, though not at a significant level. On the other hand, the subjects in the ZERO group showed either virtually no change or bad changes in CVD risk factors.

Both studies were performed on the same groups by Steven E. Black (a doctoral student) and Elizabeth Mitchell (an undergraduate honors student), both working in the laboratory of Barry Braun in the Department of Exercise Science, University of Massachusetts, Amherst. Black will present, “Improved insulin action following short-term exercise training: effects of exercise or energy balance?” while Mitchell will present “The effects of short-term exercise, in negative or zero energy balance, on CVD risk factors.”