While researchers continue to explore the underlying causes of age-related muscle decline, a more pressing concern for the rest of us is what to do about it.Getty Images/iStockphoto
You're probably weaker than you were yesterday.
This sobering fact, for those who've reached adulthood, was one of the recurring themes at last month's Canadian Society for Exercise Physiology conference in Winnipeg. By some estimates, you hit your muscular peak by the age of 25 and then begin declining, slowly at first and then with devastating rapidity. By the time you hit 80, nearly half of your muscle will have disappeared.
While researchers continue to explore the underlying causes of age-related muscle decline – is it hormonal changes? damaged DNA? lost connections between brain and muscle? – a more pressing concern for the rest of us is what to do about it. Yes, strength training works, but the high-octane workout routines of youth don't necessarily translate well to older people. How should you train to retain, and ideally regain, muscle in your 60s and beyond?
That's the question that Marcas Bamman, a professor at the University of Alabama at Birmingham, sought to address with a new study presented at the conference that compares four different strength-training routines. The results, which will be published in the journal Experimental Gerontology, suggest that neither more nor harder are necessarily better for older people.
The study involved two types of workouts. High-intensity ("H") days involved three sets of 8 to 12 repetitions to failure for each of 10 different upper- and lower-body exercises. Low-intensity ("L") days involved three sets of 12 repetitions of the same exercises, but with a much lower weight, just two-thirds as heavy as the high-intensity days.
Sixty-four volunteers between the ages of 60 and 75 did 30 weeks of training, divided into four groups. Two groups trained three times a week, with one doing all high-intensity workouts (HHH) and the other inserting one lower-intensity workout (HLH). Two other groups trained twice a week (HH or HL).
For younger adults, the simple rule of thumb is that the more hard work yields better results. But in this case, the HH and HHH groups had very similar results in many outcome measures. Adding an extra hard workout didn't provide any extra benefit – possibly, Bamman suggests, because signs of inflammation lingered in the subjects' muscles for longer than they would in younger people. With three hard workouts a week, they simply couldn't recover fast enough to benefit from the extra session.
Surprisingly, the best overall results came from the HLH group. For reasons that aren't entirely clear, the extra light workout triggered more muscle growth without compromising recovery. Importantly, the extra muscle also translated into functional gains. The HLH volunteers came out ahead in some measures of leg strength and were the only ones to register decreases in the physiological stress incurred by walking at a modest pace of 4.8 kilometres an hour.
Is the extra "L" workout worthwhile? "Two bouts per week are more practical for broad implementation and HH is pretty effective," Bamman says, "However, there seems to be added value to the midweek 'L' day for overall functional capacity, so when feasible I would still recommend HLH."
There are a few additional wrinkles. For arm strength, the best approach was HHH – presumably, Bamman explains, because arms aren't weight bearing so they get more rest between sessions than legs, and can handle a higher training load. So if you're doing three sessions a week and feel gung-ho, you can work your arms hard on the L day while taking it easy on your legs.
You should also make sure you're getting enough protein to trigger the maximum muscle growth from your workouts. One of the other insidious effects of aging, according to research led by McMaster University's Stuart Phillips, is that your muscles become less sensitive to the growth trigger provided by protein – so older people, perhaps surprisingly, need more protein than younger people even if their workout is less intense.
In Bamman's study, the subjects consumed a whey protein supplement before and after their workouts. But that's probably not necessary, he says. Instead, get enough protein throughout the day, spreading it across meals rather than packing it all in at dinner. About 0.4 grams of pure protein (or 0.5 grams of protein from whole foods) per kilogram of body weight with each meal should max out the benefits.
So is this the only workout routine that will cure age-related muscle loss and lower your risk of associated side-effects such as osteoporosis, osteoarthritis and insulin resistance? Not necessarily, Phillips says.
"There are so many variables in resistance training – sets, rest, per cent of one-rep max, exercise order, exercises to include, free weights versus machines, periodization – that I don't see how you can find what's 'optimal,'" he says.
Still, the findings offer a useful starting point. Three hard days is no better than two. And, perhaps most importantly, training keeps working throughout your life. The subjects in the HLH group added about two kg of muscle, on average, and increased their strength by 20 per cent to 30 per cent. They, unlike most of us, aren't weaker than they were yesterday.
Alex Hutchinson's latest book is Which Comes First, Cardio or Weights? Follow him on Twitter @sweatscience