Is Age-Related Decline Inevitable?

HOW DOES PHYSICAL performance change as we get older? And how much of that is due to changing activity/training patterns, rather than age itself? These are tricky questions to answer, but masters athletes – that growing cohort of people who buck the societal trend and keep hammering as they get older – offer a useful test group. Here’s some data from a new study in the European Journal of Applied Physiology, from researchers in France and Australia, on masters triathletes:

The study is particularly interesting because they went to great lengths to ensure that the various groups (there were 10 subjects in each age group) all trained at similar levels. In this case, the subjects were triathletes who logged about 250 km/week on the bike. (The heaviest training group, the under-30s, was hitting 260 km/week on average; the lightest training group, 30-39, was hitting 243 km/week. That’s a pretty small spread.)

The main thing the researchers were interested in is cycling efficiency, which is basically the amount of useful work performed on the bike divided by the amount of energy the cyclists burned to produce that work (measured in this study at 65% of maximal aerobic power). Studies of masters runners have suggested that running efficiency doesn’t change much with age; cycling studies have produced equivocal results. The new study offers some powerful evidence that cycling efficiency does decline with age. Why is this? One possible explanation is “decreases in muscle mass, motor unit remodelling and alterations in motor unit recruitment that occurs with advanced ageing” – in other words, the physical and neural characteristics of the muscle itself.

I’ve also included the changes in VO2max and peak sprint power (measured in a series of 5-second sprints), for comparison. They both seem to decrease to similar degrees, in a more pronounced manner than efficiency. In fact, declines in peak sprint power were closely correlated with declines in aerobic capacity and efficiency: the biggest decliners lost the most ground in all three categories.

So is this a measure of “intrinsic” ageing? It’s not that simple. These masters triathletes are certainly fit, but they may well be neglecting the types of training that maintain muscle mass, strength, and power. Indeed, a study back in 2011 (with one of the same co-authors) found that (a) strength training improves cycling efficiency, and (b) the improvements are bigger in older cyclists. The new study offers another bit of suggestive evidence that strength training becomes increasingly valuable for endurance athletes as you get older.



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