We’re often told that exercise is the best medicine and now the saying has a backing in science. It now seems that regular high intensity interval training (HIIT), in particular, is great for reversing the declining ability of our mitochondria to generate energy. HIIT consists of short bursts of very intense activity, combined with recovery periods of lower-intensity exercise. A trial at the Mayo Clinic in Rochester, Minnesota, focused on groups of people aged between 18 and 30 and between 65 and 80 to three months of interval training, weight training or a combination of the two. Biopsies from muscle were taken before and afterwards to measure the impact of these regimes on their cells.
Interval training boosted the ability of the mitochondria within cells to generate energy by 69 per cent in older volunteers, and by 49 per cent in the younger group. Mitochondrial activity declines with age, which may exacerbate fatigue and reduce the size and capability of muscles to burn surplus blood sugar – a risk factor for diabetes. But this decline was halted and even reversed in the older interval-training group.
Interval trainers also saw an improvement in lung, heart and circulation health. The amount of oxygen they could inhale and consume at full tilt rose by 28 per cent in the younger group and by 17 per cent in the older group. There was no corresponding change among weight trainers, although combination training boosted oxygen consumption by 21 per cent among older exercisers.
The greatest benefit from weight training was the addition of new muscle mass, but it triggered none of the mitochondrial and respiratory benefits. The combination regime generally produced intermediate results.