Sleep and sprint speed needed for optimal physical performance in field sports

How much sleep do I need for optimal physical performance?

For top athletes, getting enough sleep has long been considered the sort of bland good advice that is obvious but easy to ignore—like eating lots of vegetables. A pair of recent pilot studies by Charles Samuels, the medical director of the Centre for Sleep and Human Performance in Calgary, confirms that poor sleep quality is prevalent even in Olympic-level athletes (in this case from the national bobsleigh and skeleton teams). But the problem is even worse for ordinary people: “It’s average athletes who are the most likely to curtail their sleep to train,” Samuels says. “They’re getting up at 4 a.m. to run for an hour so they can get to work by 7 a.m.”

That’s not necessarily a winning strategy, especially for people who are already operating on the least amount of sleep that they can handle. Incurring a steadily mounting sleep debt has well-known effects on mood and cognitive ability, and a few studies are now suggesting that sleep also has direct links with physical performance. For example, Stanford University sleep researcher Cheri Mah has conducted a series of small studies testing athletes on the university’s teams. When five varsity swimmers increased their sleep time to ten hours a night from their typical six to nine hours, they slashed 0.15 seconds from their reaction time off the start and similarly improved their turn time, 15-meter sprint time, and kick rate. Similarly, increased sleep improved sprint time and free-throw percentage for a group of basketball players.

With only a few participants and no control group, these results are far from definitive, but they represent a first step to quantifying the athletic benefits of sleep. Samuels, meanwhile, has been working on a project with the Canadian downhill ski team to investigate the link between inadequate sleep and injuries, as well as studies of how globe-trotting athletes can best adjust to crossing time zones.

It’s still a challenge to apply these results in the real world. “I know it sounds ridiculous to get 10 hours of sleep a night,” Mah admits. “That’s an extreme.” For the typical person, she says, consistently increasing the amount of nightly sleep by even a small amount can produce positive effects. Most adults need seven to eight hours of sleep nightly, while teens and young adults need nine or more, though there’s quite a bit of individual variation. One of the most interesting implications of her studies with varsity athletes is that even just a few weeks of concerted sleep catch-up has a measurable effect on performance—something to keep in mind before the next big game or race.

It’s also worth noting that, just as sleep helps exercise, the converse is also true. A 2010 study from the Federal University of São Paulo found that moderate aerobic exercise (but not strength training or heavy aerobic exercise) increased reported sleep time by 26 percent in a group of chronic insomniacs. One caveat, notes Samuels, is that exercise in the three hours before bedtime can actually hinder sleep in adults in their 30s and older—if they already struggle with sleep. “If you’re a good sleeper,” he adds, “nothing matters.”

How should I pace myself in a long-distance race?

The usual advice, lifted straight from Aesop’s Fables, is that slow and steady wins the race. This is a prudent approach, especially for inexperienced racers, whether you’re running, biking, swimming, skating, rowing, snowshoeing, or undertaking any other activity where you’re hoping to reach the finish line at precisely the moment that you expend your last ounce of energy. But for those who have already run a few races and are looking to improve their time, research suggests a higher-risk, higher-reward approach.

Exercise physiologist Robert Kenefick and his colleagues at the University of New Hampshire tested various pacing strategies for the most popular road race distance, 5K, in a 2006 study. He had test subjects—who were serious recreational runners but not elite athletes—run a series of races with the speed of the first mile carefully controlled, either at an even pace based on their best time, or 3 or 6 percent faster. To everyone’s surprise, the fastest overall times came from the fastest opening mile, while the slowest races came from running an even pace. The researchers measured physiological variables such as oxygen use and heart rate while the runners ran, but they couldn’t detect any difference between the paces.

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This finding is consistent with observations of the fastest runners in the world. Ross Tucker and his colleagues at the University of Cape Town in South Africa analyzed every men’s world record ever set over 5,000 and 10,000 meters on the track for a study in the International Journal of Sports Physiology and Performance. The pattern is remarkably consistent: a fast start, gradually slowing during the middle of the race, then a fast finish. In fact, in 63 of the 64 world records they studied, the first and last kilometers were faster than any other kilometer in the race. The only exception was Paul Tergat’s 1997 record over 10,000 meters, in which the ninth kilometer was one second faster than the tenth kilometer.

This fast finish isn’t necessarily a deliberate strategy. Rather, Tucker argues that it reflects “anticipatory regulation” of effort, in which your conscious and unconscious minds work together so that you reach the finish line having worked as hard as possible, but maintaining a reserve to ensure that you don’t collapse prematurely. This is why prior racing experience is essential for an aggressive pacing strategy: your brain needs some basis of comparison to figure out when the end will come.

Exercise scientists sometimes refer to the effects of knowing where the finish line is as “teleoanticipation.” Studies over the course of several decades have shown how powerful these effects can be. For example, researchers in a 1980 study told one group of volunteers to run on a treadmill for 20 minutes and told another group to run at the same pace for 30 minutes—but stopped both groups after 20 minutes. Even though the physical demands were identical, the subjects who thought they would have to run for another 10 minutes reported much lower ratings of perceived exertion, showing that our feelings of fatigue are linked to when we expect to finish.

These findings don’t mean that you should sprint all-out off the starting line and simply hope to hang on. The best performers in Tucker’s study were those who started fast but then managed to settle into a steady pace, rather than getting steadily slower throughout the race. So be cautious at the start—but don’t be afraid to push a little faster than your expected final pace. “Either way, you’re tired at the end,” says Kenefick, who is now a U.S. Army research physiologist. “So if you go out too slow, you can’t make that up at the end.”

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Is endurance or sprint speed more important in field sports like soccer?

For decades, sports scientists have focused their attention on two opposite ends of the athletic spectrum: endurance and speed. But the demands of sports like soccer, rugby, and basketball don’t fit neatly into either one of these pigeonholes. Time–motion studies using GPS and video tracking have found that top soccer players cover up to 7.5 miles over the course of a typical match, which certainly requires endurance. On the other hand, games are won and lost when one player beats another to the ball by a few inches. The same analyses find that players make somewhere between 20 and 60 short, all-out sprints during a match, each lasting two to four seconds and covering 10 to 30 yards. It’s this “repeated sprint ability” that separates good players from great ones, and scientists have finally started studying how to improve this trait.

The first time you sprint during a game, about 80 percent of the energy you need is provided by short-term fuel sources that don’t require any oxygen, while the remaining 20 percent is aerobic. With short recoveries between sprints, the aerobic component rises to about 50 percent when you make your third sprint, and eventually reaches about 75 percent for each sprint after you’ve been playing for a while. At this point, according to McMaster University researcher Stuart Phillips, you’re relying on carbohydrate stores in the same way long-distance runners do. As a result, the optimal fueling strategies are essentially the same as for endurance challenges: make sure your carbohydrate stores are full before the game starts, and keep topping them up throughout.

So what’s the best way to improve your ability to keep sprinting late in the game? In a 2010 study, French researchers compared two approaches. One group of elite teen soccer players focused on developing their explosive strength once a week, performing a series of drills, including vertical and horizontal jumps, hurdles, and sprints. Another group focused on repeated sprint training, doing up to three sets of six shuttle sprints (running 20 meters, touching the ground, then returning to the start position as quickly as possible) with about 20 seconds of rest between sprints. Both groups improved the maximum speed for a single sprint, but only the second group improved their times for repeated sprints—a crucial distinction, since several studies have found that performance on repeated sprint tests is a strong predictor of better performance in matches.

Similar patterns are seen in other sports. Rugby is similar to soccer, with players covering about six miles and spending about 25 percent of that time in the “critical performance zone” where they’re chasing a ball or an opponent at close to maximum intensity. In ice hockey, players cover only about 2.5 miles but spend half that time in the critical performance zone. Basketball players, competing on a smaller surface, cover about 1.3 miles and spend 20 percent of that time in the critical performance zone. Each sport has slightly different demands, but they all have a start-stop rhythm that you can prepare for by doing repeated sprints with short rests and rapid changes of direction.

CHEAT SHEET: THE COMPETITIVE EDGE

• Gradually reduce your training volume by 41 to 60 percent over a period of 8 to 14 days before a competition to maximize performance. Don’t change training frequency or intensity.

• Sex before competition is unlikely to have any physical effects but could affect mental readiness. Stick to a familiar routine.

• Downing a slushy ice beverage can lower your core temperature enough to boost endurance on hot days.

• Caffeine is a powerful performance enhancer, acting as a stimulant and directly on your muscles; coffee has less predictable effects due to its complex mix of ingredients.

• Competing in a familiar environment may offer greater advantages than having a large crowd cheering you on, though individual responses vary.

• Getting enough sleep boosts performance; even just a few weeks of concentrated sleep catch-up has measurable effects on speed and reaction time.

• Contrary to the usual advice, a slightly faster start may help you finish with a quicker time than a perfectly even pace in long races.

• To train for the mix of speed and endurance required in field sports like soccer, practice repeated shuttle sprints (20 meters) with sharp turns and short recoveries (20 seconds).

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