How much age-related physical decline is inevitable, and how much is the result of the changing priorities and social pressures that force most 45-year-olds to be less physically active than they were in their teens and 20s?
It's a tricky question, but one place to start is with the remarkable group of 60 triathletes assembled by Dr. Jeanick Brisswalter of the University of Nice Sophia Antipolis and his colleagues in France and Australia. They range in age from their 20s to their 70s, but have one thing in common: they all train for about two hours each day on average, including about 250 kilometres of cycling a week.
Even these remarkable athletes can't completely outrun – or outswim or outbike – the ravages of time, but studies of masters athletes (typically over the age of 35 or 40, though the definition varies from sport to sport) are reshaping our understanding of how much decline is "inevitable," and why it happens. The latest results suggest that even trained athletes get less efficient as they age – and surprisingly, the secret to avoiding this fate lies not in the heart or lungs, but in the muscles.
It's well established that VO2 max, a measure of endurance, and sprint power decline steadily starting in your 30s or 40s, and despite their Herculean training efforts, the triathletes in the new study were no exception, although the 70-plus group was still fitter than the average sedentary 35-year-old.
Most previous studies of masters athletes have focused on these parameters, and concluded that this loss of endurance and sprint power are enough to explain why older athletes are typically slower than younger ones.
But Brisswalter's study, which will appear in a forthcoming issue of the European Journal of Applied Physiology, zeroed in on a third factor: efficiency. In cycling, efficiency measures how much metabolic energy you have to burn to maintain a given pace or power output on the bike, much like the fuel efficiency of a car. Similar efficiency measures can be calculated for running and swimming.
The results showed a clear decrease in efficiency starting with the 50-59 age group. By the time they were in their 60s, the athletes had to burn 17.6 per cent more energy than athletes in their 20s just to produce the same amount of power on the bike – a significant deficit.
So how do you improve cycling efficiency? In beginner cyclists, simple improvements in form and technique may help. For experienced cyclists, better efficiency may result from changes in the muscles themselves, though this hypothesis remains controversial. For years, the most famous case study of improved cycling efficiency came from tests of Lance Armstrong by University of Texas physiologist Dr. Edward Coyle between 1992 and 1999 – but those results are now considered highly questionable.
In 2012, another group of French researchers (including Brisswalter) tested the effects of a three-week strength-training program on cycling efficiency in two groups of athletes, one with an average age of 26 and the other with an average age of 52. Three times a week, they did 10 sets of 10 knee extensions at 70 per cent of maximal load, with three minutes of rest between sets.
The younger athletes were stronger and more efficient to begin with, and didn't make any significant gains by the end of the program. The older athletes, on the other hand, improved their leg strength by 17.9 per cent and also improved their cycling efficiency by 16.3 per cent, enough to completely eliminate their efficiency deficit compared with the younger group.
That result lends support to the theory that declining efficiency is a result of changes in muscle properties, both from loss of muscle mass and from changes in the neuromuscular signals that travel from the brain to the muscle. Other studies have suggested that running efficiency may also be linked to muscle strength and power.
The most promising antidote, then, seems to be strength training. Brisswalter recently completed another study with masters cyclists, not yet published, that saw improved cycling efficiency after strength training. That's also the approach taken by Kingston-based running coach Steve Boyd, who holds Canadian masters records at distances ranging from 3-kilometre to the half-marathon, and attributes his longevity in part to consistent work in the weight room.
He recommends a full-body workout that incorporates upper-body exercises such as the dumbbell press and single-arm row, and lower-body exercises such as the Bulgarian lunge and Swiss ball curl.
Of course, strength training alone won't make you a great runner or cyclist. But accelerated muscle loss due to the hormonal changes associated with aging mean that it takes on greater importance as you get older.
"In fact, at 50," Boyd says, "I consider my strength training as important as my running."
Alex Hutchinson blogs about exercise research at sweatscience.runnersworld.com