Big breakthroughs grab the headlines, but health research progresses slowly and incrementally. As a corrective, here's a progress report on five topics that have seen notable developments this year.
Will too much exercise kill you?
The background: A study of 53,000 patients at the Cooper Clinic in Texas produced a counterintuitive finding: Those who exercised the most were seemingly no healthier than those who didn't exercise at all. Instead, the biggest longevity benefits accrued to those who exercised "moderately," the equivalent of running less than 32 kilometres a week.
The update: This debate continues to simmer, with several researchers questioning the methodology of the original study. One problem is the accuracy of self-reported exercise data. A better solution is to look at aerobic fitness (sometimes referred to as VO2 max), which can be measured objectively. A long-term study of 38,000 patients by researchers at Johns Hopkins University, published this year in the Journal of the American College of Cardiology, found that greater fitness was linked to greater longevity, with benefits that continued to increase even at the very highest levels of fitness.
The background: For athletes of all levels, overuse injuries such as tennis elbow and Achilles tendinosis are common hazards. Despite the promise of newer therapies such as platelet-rich plasma injections and nitroglycerin patches, these tendon problems remain stubbornly persistent and difficult to treat.
The update: In a British Journal of Sports Medicine study published online in October, researchers from the University of Cape Town review the growing evidence that tendon injuries run in families. A small number of gene variants affect the structure of collagen fibrils, the underlying units of tendons and ligaments, leaving some people more susceptible than others to tendon injuries. Does knowing you're susceptible help you avoid these injuries? That's what direct-to-consumer genetic testing companies are claiming, but the authors of the review remain skeptical about the benefits of such tests – for now.
The brain benefits of exercise
The background: It's increasingly clear that exercise is as good for the brain as it is for the body. You'll score better on cognitive tests immediately after a moderate workout, and the gains accumulate over weeks of regular exercise. The mechanism is thought to involve a rise in growth-promoting brain chemicals and neurotransmitters, but it's not clear how much or what type of exercise is most effective.
The update: To investigate the optimal brain-boosting exercise dose, a University of Kansas study assigned older adults to walk for between zero and 225 minutes a week for 26 weeks. As little as 75 minutes a week was enough to improve scores on a battery of cognitive tests, and there were further gains all the way up to 225 minutes. The overall pattern was that those who made biggest improvements in aerobic fitness also saw the biggest boosts in cognitive scores. Get your body fit, in other words, and the brain will follow.
Boosting fuel efficiency
The background: The biggest engine doesn't always win the race. Particularly over long distances, it also helps to be efficient – to consume as little energy as possible while pedalling your bike at a given rate or running at a given speed. But we know very little about what types of training boost cycling and running efficiency.
The update: Researchers at the University of Verona, in Italy, recently presented the results of a study in which runners with an average age of 44 were assigned to either run and do leg-press exercises to strengthen their legs, or just run for eight weeks. The strengthening group improved their running economy (a measure analogous to gas mileage in a car) by 5 per cent – without adding any muscle mass. That suggests the neuromuscular connections between brain and muscle, rather than the muscle itself, hold the key to boosting efficiency.
The background: Why are we so good at coming up with excuses to skip a workout? In surveys, we claim we're too busy; but the rise of high-intensity workouts that require less than 10 minutes a couple of times a week make that excuse less plausible. Instead, some researchers argue that the feeling of effort is the biggest barrier, a powerful evolutionary hangover that encourages us to be as "lazy" as possible and avoid wasting energy.
The update: In a recent editorial in the journal Sports Medicine, University of Kent researcher Dr. Samuele Marcora argues that we should try to develop psychoactive drugs that reduce the perception of effort during exercise (or enhance positive feelings such as "runner's high"). This may feel like unneeded medicalization of laziness, Marcora acknowledges, but reducing barriers to exercise could have enormous public health benefits. Besides, he adds, we don't seem to have any problem with using caffeine for this purpose.