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23.10.2009

Old muscles weaker, but tire less quickly than young ones

It may not be clear yet whether it has consequences for optimising strength training practices for elderly people, but Eric Rawson's study is definitely interesting. This sports scientist from Bloomsburg University in the US discovered that although the muscles of the over-sixties are not as strong as those of students, they tire less quickly. Old muscles are tougher.

Rawson got nineteen men aged between 60 and 82 to do five sets of thirty reps on a leg-extension machine. A group of sixteen younger men aged between 16 and 24 did the same. The men rested for one minute between sets. Rawson measured the strength – the peak torque – that the men managed to develop during each rep, using an isokinetic dynamometer.

The figure below shows what happened to the men's strength during the first two sets.

Young muscles are stronger, but the strength they are able to develop declines rapidly during a set.

The figure below gives the same information, but for five sets. The researchers calculated the average strength per set. So it's not only during a set, but throughout a series of sets too that young muscles lose strength more quickly.

Going by previous studies, Rawson suspects that muscles that age healthily acquire their energy in a different way. Glycolysis, the process through which muscles convert glucose into energy, becomes less important. Oxidative phosphorylation – making, using and recycling the energy molecule ATP – is a more important process in old muscles.

Rawson is interested in fundamental science. He's not concerned with whether his study has implications for the way in which elderly people can improve their strength training practices. Unburdened as we are with excess knowledge, we are happy to air a few suggestions. Here goes.

Maybe elderly people react better to a low-carb diet. Or maybe elderly people do better when they train with more sets and more reps. Volume training, say.

Source:
J Strength Cond Res. 2009 Aug 5. [Epub ahead of print].