Overspeed training

Does making your legs work faster than normal actually make you a quicker athlete?

Exercise scientists and athletes have debated the benefits of treadmill workouts ever since the device became popular. Currently, the consensus is that the treadmill can provide runners with an extremely intense, very controlled training session (the extra control comes from the ability to set the machine at a precise pace), that the treadmill can create hill-climbing workouts for environmentally challenged athletes who live in flat parts of the country (after all, the gradient on most decent treadmills can be jacked up to at least 25 per cent), and that the treadmill offers athletes a chance to get in some top-level running on days when weather conditions would normally stymie training.

 However, there’s a potential down side to treadmill workouts, too. Many athletes feel that treadmill running is biomechanically dissimilar from regular-terrain running. In fact, many claim that too-much treadmill running can spoil one’s economy and efficiency when running on normal ground (although this contention has NOT been scientifically verified).

Take the weight off your feet
Now there’s a new twist to the treadmill argument: some treadmill advocates are contending that one should run regularly on the treadmill in the UNWEIGHTED state. The idea is to let your legs scurry along, making quick contacts with the treadmill belt without having to support your full body weight. After all, the great weight of your torso could be held in place by a harness, freeing your legs to spin at Roger Black-like tempos. You’d be teaching your legs to work at unprecedented speeds, the notion being that some of this leg lightning would still be present when you went back to firm-ground running.

Basically, such unweighted treadmill running is a form of ‘overspeed’ training, which means forcing your muscles to work at a higher intensity than they normally do. We know from sound scientific research that overspeed training heightens throwing velocity in baseball pitchers and cricket bowlers (who ‘overspeed’ by throwing a lighter-than-normal ball), and bolsters power in strength trainers (who ‘overspeed’ by lifting a lighter-than-normal weight more quickly than usual). So why shouldn’t overspeed training (slipping into a harness and pacing frantically on a treadmill) work for runners, too?
Basically, putting on a harness and spinning your legs along the treadmill belt represents a way to train those fast-firing nerve cells which control movements and coordinate leg-muscle activity during very quick contractions. It also ‘teaches’ muscle cells to function at accelerated firing rates. Exercise physiologists reckon that it’s easier to accomplish this if the nerves and muscles don’t have to simultaneously worry about supporting full body weight (in fact, some scientists argue that the nerves and muscles might never learn to function at rapier-like speed if they’re bogged down with weight-bearing). Thus – the principle of unweighted treadmill running.

Runners have been at it for years
If you’re a bit taken aback by the idea, bear in mind that although unweighted treadmill running is new, overspeed training is not at all a novel idea in the running community. For decades, various running coaches have encouraged their runners to conduct some of their workouts on a slight downhill grade, which makes it easier to rocket along at uptempo paces (this was a fairly common practice in Finland, for example, during the heyday of Lasse Viren and other great Finnish runners). More recently, runners have ‘oversped’ while being towed with a rope attached to the rear bumper of a car – or while being propelled forward by a large, long rubber band.

Unweighted overspeed training on the treadmill sounds okay so far, but how about some evidence? Well, a physical therapist named Malcolm Macaulay at the University of Minnesota-Duluth had been using a treadmill harness to help runners recover from injuries for several years when two local coaches asked him to show some uninjured marathon runners how to utilise the device for overspeed training. Initial efforts with the harness seemed promising, as athletes who engaged in unweighted training made three key claims:

1) Some athletes reported that their running mechanics were drastically improved after running ‘in harness’.

2) Many runners contended that they had always felt that their leg action during running was too slow, and that the unweighted training helped them improve leg speed quickly and easily.

3) Some runners said that after unweighted training they felt much quicker during other activities. A common quote was, ‘I feel much faster on the tennis court now, and my leg speed during bicycling is also improved.’
Not content with mere anecdotal evidence, Macaulay carried out a study in which five male runners of above-average ability (VO2max = 57 ml/kg.min) used harness treadmilling as they prepared for half-marathon and marathon races, while five similar runners preparing for the same competitions avoided unweighted-overspeed work. All of the runners were experienced and had previously competed in a marathon.

Twice a week, the unweighted group slipped into a harness which supported about 25 per cent of body weight (eg, required the leg muscles to support just 75 per cent of normal weight) and ran at unprecedented speeds on the treadmill. In fact, their average velocity in harness was about 22 per cent faster than the normal speed they would have utilised during speed workouts. Meanwhile, the control (non-overspeed) group also worked out in harness on the treadmill, but the harness supported no body weight, and they ran at their normal training tempos.

The bottom line?
Unfortunately, the unweighted training also produced weightless results. Unweighted work did not improve running economy, compared to regular running, nor did it accelerate one-mile or 5-K race times (‘Effect of Overspeed Harness Supported Treadmill Training on Running Economy and Performance,’ Medicine and Science in Sports and Exercise, vol. 27(5), Supplement, 1995).

Undeterred, Macaulay still thinks that harness exertions will work well for many runners. ‘One of the problems with our research is that we had the unweighted and weighted runners train at similar perceived efforts during their speed sessions. If we had let the unweighted runners achieve the same heart rates or oxygen consumption rates as the non-harness athletes, the results might have been different,’ he contends.

‘Unweighted running offers runners and other athletes a way to improve endurance and speed with less injury risk,’ Macaulay says. ‘It’s also useful for novice runners, as it allows running with less trauma to joints.’ True enough, but we’ll still have to wait to see whether jumping into a harness can really help you harness more power in your legs!

Owen Anderson

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