The Science of Running

By Alex Hutchinson The Sacred Cows of Running: the Warmup, the 10-Per-Cent Rule, Stretching and the Inevitability of Aging

Science, Isaac Asimov once said, is “a system for testing your thoughts against the universe and seeing whether they match.” Sometimes they don’t match – and that’s OK, because discovering that a cherished belief is wrong is the crucial first step to learning something new. Here are four things from the running world that scientists are currently challenging The Warmup

Rare is the runner who would dare to jump straight into a race or hard workout without some sort of warmup ritual – a light jog, at the very least, possibly followed by a series of drills and sprints. There’s a sound theoretical basis for the warmup: literally raising the temperature of your muscles makes them more supple, which presumably reduces injury risk. Warming up also seems to speed up some of the metabolic reactions that fuel hard exercise, which should give you a performance boost.

But actually demonstrating the performance-boosting potential of warmups for prolonged endurance events turns out to be trickier than you’d think. Earlier this year, researchers at the European University of Madrid published a study in the International Journal of Sports Physiology and Performance that compared a long warmup, a short warmup and no warmup at all before a series of tests, including a 20-minute cycling time trial. For short bursts of power like a vertical jump, the warmups helped. For the time trial, they made no difference.

That certainly doesn’t mean warmups are useless. But for longer events like 10ks, half-marathons and marathons, the risk of injury from a sudden start is lower (as long as you’re not sprinting at the start) and the performance benefit appears to be negligible. For a marathon in particular, you don’t want to waste precious glycogen stores that you’ll be needing in the last few kilometres. Still, warmups can be a useful ritual that helps calm you down and get you into the zone – so do what you need to do, but don’t stress if something disrupts your routine.

The 10-per-cent Rule

The standard advice for many decades has been that to minimize your risk of injury and overtraining, you should avoid jumps of more than 10 per cent in your weekly mileage. More recently, researchers and coaches have adopted a more sophisticated version of the same principle, called the acute-to-chronic workload ratio ( acwr). The acwr compares your most recent week of mileage to the average of your four previous weeks. If you run weeks of 30, 25, 30 and 35 kilometres, your acwr is 35 divided by 30, which is 1.17. The jump from 30 to 35 kilometres is a 17-percent increase in one week, well above 10 percent. But several studies have found that injury risk only increases once your acwr exceeds 1.3, so this progression would get a green light under the new system.

In a recent review in Sports Medicine, a team of McGill University researchers led by Ian Shrier challenged some of the ideas underlying this approach. For one thing, any ratio – whether it’s the 10-per-cent rule or the acwr – ignores the absolute size of the load. Increasing from 10k to 12k in a week is much less risky than increasing from 100k to 120k, but ratios can’t tell the difference. Weekly averages also ignore how the training is distributed within a week: especially long or hard runs may raise your risk more than a balanced schedule with the same total mileage.

In reality, few injuries have a single, easily identifiable cause. Other factors like biomechanics, injury history and sometimes plain old luck play a role. Slavish adherence to either the 10-per-cent rule or the acwr won’t make you invincible – but personally, I still think they offer a useful warning sign to consider as you plan your training.

Stretching

Hang on a sec while I change my phone to an unlisted number and put up a filter on my email account.

OK, here goes. Routine static stretching of the type we all learned as kids won’t protect you from injury, won’t prevent you from getting sore afterward, won’t make you run faster and in some cases may even make you run slower. That’s the gist of another review article in Sports Medicine by American exercise scientist James Nuzzo, summing up decades of research and hundreds of studies on stretching.

This is not a new argument. In fact, Ian Shrier, the acwr critic from McGill, published a widely cited article in the Clinical Journal of Sports Medicine way back in 1999 arguing that stretching doesn’t reduce the risk of injury. But the fitness world has been slow to update its views: one 2016 study found that 80 per cent of accredited personal trainers still assign

Routine static stretching of the type we all learned as kids won’t protect you from injury, won’t prevent you from getting sore afterward, won’t make you run faster and in some cases may even make you run slower.

static stretching to their clients.

Like the other debates discussed above, there’s plenty of nuance to the stretching debate. Static stretching is certainly the best way to enhance your static f lexibility; if you want to touch your toes or do the splits, stretch on. But specifically within the context of long-distance running, many elites have switched their emphasis to dynamic f lexibility, incorporating drills like walking lunges and high knees into their warmup routines. The science seems to agree with them – at least for now.

The Inevitability of Aging

Let’s finish with some good news. It’s true that most of your physical faculties decline with each passing year once you’re in your 40s and beyond. For example, VO2max drops by about nine per cent per decade, on average. But recent studies of record-setting masters marathons have highlighted one area where you can actually improve with age.

In the New England Journal of Medicine, researchers reported on a battery of tests they’d run on the American masters runner Gene Dykes, who ran 2:54:23 at age 70 in late 2018. (It would have been a world age-group record, except that the Jacksonville Marathon, where he achieved it, is not sanctioned by the usatf.) Throughout his marathon, Dykes sustained an incredible 95 per cent of his VO2max, far higher than the 75 to 85 per cent expected of younger elite marathoners. Skeptics figured the measurement must have been f lawed. But earlier this year, another research team studied former Irish Olympian Tommy Hughes, who ran 2:27:52 at the 2019 Frankfurt Marathon at age 59. In that race, he sustained a similarly mind-boggling 91 per cent of his VO2max, they reported.

The upshot: the sands of time may gradually rob you of your top gears. But with accumulated wisdom, grit and years of sustained training, you can learn to run closer to your max and hold it for longer. Chalk it up as a moral victory.