To reap the benefits of a hard workout, you have to let your body recover afterward. That's an inescapable part of the training cycle – stress, recovery, adaptation – and it's why top athletes are so devoted to ice baths, compression garments and other recovery aids.
But what if, as researchers and coaches have recently begun to speculate, there can be too much of a good thing?
Two new studies, one on ice baths and the other on antioxidant supplements, add to the evidence that more isn't always better when it comes to accelerating post-exercise recovery. The findings suggest that the balance between stress and recovery is a delicate one, and in some cases you may be better off letting your body recover at its own pace.
The ice-bath study, published in the Journal of Physiology by a team of researchers led by Llion Roberts of the University of Queensland and the Queensland Academy of Sport in Australia, involved 21 volunteers who lifted weights twice a week for 12 weeks. Each workout was followed by either a 10-minute ice bath at 10 C degrees Celsius or 10 minutes of easy cycling on a stationary bike.
Strength and muscle mass, as well as the size of individual muscle fibres, increased more in the control group than the ice-bath group. "We were very surprised at the magnitude of this response in our subjects," Roberts said.
In a follow-up study, the researchers used muscle biopsies to measure the cellular signals that trigger muscle growth in the hours immediately after a workout, with and without an ice bath. Again, muscle-growth signals were suppressed in the ice-bath group.
While Roberts and his colleagues are pursuing further studies to figure out exactly why this happens, the results are consistent with the idea that post-exercise recovery – how you'll feel the morning after a workout – and training adaptations – how strong you'll be in a month – are inextricably linked. The inflammation and soreness that plague you the morning after a workout are also telling your body that it needs to adapt.
One component of that response is oxidative damage, as a class of molecules called reactive oxygen species, generated during intense exercise, overwhelm the body's natural antioxidant defences and contribute to muscle damage, weakened immune function and fatigue. It seems logical, then, that athletes should counter this threat by taking antioxidant supplements.
But a review of 71 studies, published in the journal Sports Medicine by researchers in New Zealand and Australia, suggests that regular use of antioxidant supplements can also interfere with training adaptations.
While there is some evidence that antioxidants such as vitamin E can boost performance when taken shortly before a competition, the "harmful" reactive oxygen species also seem to play a helpful role in signalling that the body needs to adapt and get stronger. As a result, even modest supplement regimens, such as 1,000 milligrams of vitamin C daily, have been shown to reduce gains in strength and endurance from training over longer periods of time.
"This is actually one of the most common issues I address when reviewing supplements with athletes," Nicole Springle, the head of sport nutrition at the Canadian Sport Institute Ontario, says.
Many athletes are surprised to learn that their vitamin C and other pills could be hindering their training rather than helping it. Springle steers them instead toward antioxidant-rich food sources and away from megadose supplements. It's part of a broader shift, she says, as "athletes in general seem to be becoming more accustomed to the 'more isn't always better' mentality."
Still, it's important not to leap to the other extreme and assume that enhanced recovery is always bad. Roberts points out that, while ice baths seem to interfere with strength training, initial evidence suggests that they don't interfere with endurance training. The delicate balance between enough and too much recovery probably depends on the specific type and amount of exercise, as well as the specific type of recovery aid.
For now, some coaches are suggesting that athletes "periodize" their use of recovery techniques, which means adopting different strategies at different points in your training cycle. If you're in a period of heavy training where the goal is to increase fitness, minimize your use of ice baths, antioxidants and so on; as you approach an important competition, ramp up your use of recovery aids to ensure that you're at full strength.
The research also suggests a more subtle shift in how we think about the aftermath of a tough workout. The heavy legs and aching muscles are, within limits, something to be embraced rather than wished away: They're the tangible signs that you're getting fitter.