NEW: Exercise counteracts the effects of short-term overfeeding and reduced physical activity independent of energy imbalance in healthy young men
Jean-Philippe Walhin, Judith D Richardson, James A Betts, and Dylan Thompson
To manipulate energy balance to determine its extent on physical activity.
Twenty-six active men were randomly assigned either to one of two groups:
1. SUR GROUP (n = 14). Consume 50% more energy than normal by over-consuming their habitual diet for 7 days while simultaneously restricting their physical activity below 4,000 steps day to induce an energy surplus (SUR).
2. SUR + EX GROUP (n= 12) Follow the same regimen but add 45 minutes of daily treadmill running
at 70% of maximum oxygen uptake (SUR+EX).
The SUR+EX group received additional dietary energy intake to account for the energy expended by
exercise, thus maintaining a matched energy surplus.
At baseline and follow-up these were assessed:
1. Fasted blood samples.
2. Abdominal subcutaneous adipose tissue biopsies.
3. Oral glucose tolerance.
Insulinaemic responses to a standard glucose load increased 2-fold from baseline to follow-up in the SUR group but there was no change in the SUR+EX group.
Seven of 17 genes within adipose tissue were differentially expressed in the SUR group.
Expression of SREBP-1c, FAS and GLUT4 was significantly up-regulated and expression of PDK4, IRS2, HSL and visfatin was significantly down-regulated.
The pAMPK/AMPK protein ratio in adipose tissue was significantly downregulated in the SUR group.
IN PLAIN ENGLISH:
Vigorous-intensity exercise countered most of the effects of short-term overfeeding and under-activity at 1) the whole-body level and 2) in adipose fat tissue storage sites even when there was an energy surplus. Therefore, relatively short high-effort training sessions can offset increased calorie intake beyond that what is needed to fuel the efforts.