The Science of Running
Predict Your Half Time; Train Right; Recover Well
Half-marathons have been the fastest growing race distance over the past few decades, with finisher numbers more than quadrupling since 2000. Not surprisingly, running researchers have turned their attention to the distance, trying to understand what it takes to train for, race and recover from one successfully. Here are a few highlights from recent half-marathon research:
Predict Your Half Time
In a 2017 study in the Journal of Sports Science & Medicine, researchers from the University of the Basque Country in Spain tried to identify the best ways of predicting half-marathon times. They started with a group of 48 experienced runners who had recently completed a half-marathon and put them through a battery of tests: “anthropometric” measures like weight, height, and body fat percentage; training variables like weekly mileage and total years of running; physiological measures like VO2max and threshold, obtained in a treadmill test; and biomechanical measures like cadence, stride length, and ground contact time.
The researchers used all this data to develop four different equations for predicting finish times. Then they recruited another 30 runners, gave them the same tests and asked them to run a half-marathon to see how well their prediction equations performed.
All four types of measurement – body size, training, physiology and biomechanics – had good predictive ability, mostly in the ways you would expect. Height doesn’t matter, but being lighter helps. Training more, and having more years of running experience, helps. Cadence (the number of steps you take per minute) doesn’t make much difference, but having a longer stride does – something the researchers suggest you can work on not by consciously trying to take longer steps, but by doing resistance training to increase your leg strength.
The actual equations don’t have much practical use for most runners since you need fairly sophisticated equipment ( like VO2max machines) or measurements (like skinfold tests) to use t hem. But t he fact t hat all four equations had predictive value is a reminder that there’s no single secret to successful half-marathoning. Eat healthily, t rain hard, get st rong – it all helps.
Train Right
One of the most powerful predictors of half-marathon time in the Basque Country study was weekly running mileage. So you should go out and immediately start running as much as possible, right? Not so fast, because ramping up your mileage too quickly is the best way to ensure that you’ll get injured. But how fast is too fast?
In December, a team of researchers from Denmark published a study in the Journal of Orthopaedic & Sports Physical Therapy investigating exactly this question. They followed 261 healthy runners for 14 weeks leading up to a half-marathon. Their running was tracked by gps, and their injury status was assessed each week. The key question the study sought to answer was how much the runners could increase their mileage f rom week to week without significantly raising their risk of injury.
Over t he course of t he st udy, 21.5 per cent of the runners suffered at least one running injury. And sure enough, mileage increases were a risk factor: runners who increased their running distance by more than 20 per cent from one week to the next were 23 per cent more likely to get injured than those who kept their weekly increases to less than 20 per cent. Of course, generations of runners have been warned about the “10 per cent rule,” which restricts weekly mileage increases to no more than 10 per cent. The new data may suggest a slightly less caut ious t hreshold, but t he general message is the same: sudden large increases are risky.
There’s one other wrinkle in the study. The key difference was seen in the first three weeks of the study when the runners were most likely to be ramping up their training. After that, it didn’t seem to matter as much. Don’t take this as a license to double your mileage once you’re six weeks into a training block. But bear in mind that the riskiest period is when you’re just getting started or returning from a period of rest or injury. Ramp up gradually, and your body will be ready to absorb more punishment later.