Holding back the years (aerobically at least!)

In cosmology, physicists refer to the passage of time as the ‘arrow of time’ because time only flows one way – forwards not backwards.

Here on earth this means that unfortunately, we all get older and with those advancing years comes an inevitable decline in physical performance. However, recent research into the effects of aging on performance have thrown up some encouraging findings and now a new Australian study suggests that age-related performance decline in cyclists may be far less of a problem than we first believed, especially when it comes to aerobic performance.

The science
The aim of the study was to measure the relative rates of change of the three human energy systems across a 30-year age range.

In brief, these energy systems comprise of the following (although of course in many types of cycling event, two or even three of the systems can be providing energy simultaneously): the phosphocreatine system – the principal source of energy for very short (10 seconds or less) and intense bursts of exercise; the lactate system – the main source of energy for maximal efforts lasting up to three minutes involving the breakdown of carbohydrate without oxygen; the aerobic system – the energy system for sustained, less intense exercise, where fat and carbohydrate are broken down in the presence of oxygen.

A cross-section of highly trained masters cyclists (156 males and 17 females aged 35-64) were tested for maximal cycling performance.

There were 50 (29 per cent) track sprint cyclists while the remaining 71 per cent were predominantly road cycling specialists. The subjects underwent a number of tests over a period of time to track any age-related changes in performance.

These tests included a 10-second peak power test to measure anaerobic power (phosphocreatine system), a 30-second test to measure anaerobic capacity (lactate system), and a progressive test to volitional fatigue to determine peak aerobic power.

The subjects’ exercise patterns were also recorded using a physical activity recall questionnaire and the data obtained was number crunched to try and detect what effect aging had on performance.

In a nutshell
The first major finding was that (as expected), there were significant negative changes in anaerobic performance with aging. Peak anaerobic power (measured in maximum watts produced per kilo of bodyweight) declined at an average rate of 8.1 per cent per decade.

Meanwhile, anaerobic capacity declined at a very similar rate of 8.0 per cent per decade. What was very surprising, however, was that peak aerobic power didn’t change significantly with age.

Although the research measured a slight decline of 1.8 per cent per decade, this decline was so small as to be insignificant – so the slight decline measured could have arisen simply as a result of a statistical ‘blip’.

So what?
There are two points here. The first is that while anaerobic power declines markedly as the years pass, it seems that aerobic power holds up remarkably well.

The decline in this study was deemed insignificant but in a larger study, this small decline might be confirmed as an ‘actual’ decline. However, the fact remains that statistically significant or not, 1.8 per cent per decade is a very small decline indeed.

This bodes well for older cyclists, especially if they decide to switch to longer distances (where aerobic power becomes progressively more important) as they get older.

The second point is that for older cyclists wishing to maintain performance at their preferred distance, the message seems to be that anaerobic training becomes more important to stem performance decline as the years pass – not less important.

J Sports Sci. 2012 Sep 13. [Epub ahead of print]

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