Does yoga help triathletes?

Range is how far a joint can move, and how easily. In the water, your shoulder lets your arm reach long past your ear. On the bike, your hips let you fold low with a long back. On the run, the front of your hip lets your back leg swing out behind you. Why each one matters is in Stiff people work harder for every stroke.

Hours on the bike shape you off it too. A review of studies on cyclists' backs found that cyclists stand with a rounder upper back than people who do not ride. Their lower back also rounds more on the bike the lower they grip the bars.

Swimming, riding and running each move your joints through the same arc, thousands of times. None of them takes your spine to the end of its turn, or your hip to the end of its range. Fitness does not protect you either. Rugby players followed through eight weeks of their season lost 14.8 percent of their hamstring range when they did no yoga.

The rugby players who added yoga twice a week kept their range. In another study, a US college soccer team did two hours of yoga a week for ten weeks. Their range and their balance both improved. The baseball team, who did no yoga, did not change. That study was small, and the teams were not picked at random.

Both teams practised twice a week, every week. That is the point. Yoga works on range and balance together, and it works when you do it often.

In Belgium, researchers measured the muscles of 146 professional footballers before a season. Then they followed them through it. Players with tighter hamstrings or quadriceps, the muscles at the front of the thigh, were more likely to injure those muscles.

In Sweden, 75 junior basketball players had their ankles measured. Over the next year, some got jumper's knee, a painful tendon below the kneecap. Among players with stiff ankles, 18 to 29 percent got it. Among players with more ankle range, about 2 percent did.

In Australia, 74 competitive swimmers had their shoulders measured, then were followed for a year. Swimmers whose shoulders turned outward too little, or too much, were many times more likely to get pain that got in the way of training. The ones in the middle did best. So the aim is not the most range you can get. It is the range your sport needs, held with control.

Control at the end of your range is balance. And balance training has the strongest record of all.

In the Netherlands, 522 athletes who had sprained an ankle in the last two months were split into two groups at random. One group also did eight weeks of balance training at home, on their own. Over the next year, 22 percent of them sprained the ankle again, against 33 percent of the others.

That is not one lucky trial. A review pooled 25 trials of exercise programmes. In the trials of balance training, injuries fell by almost half. Range likely does its best work with balance beside it, and yoga trains both.

So the two links line up. Yoga done often builds range and balance. Athletes with more range get hurt less, and balance training cuts injuries. Keeping both with yoga should lower your risk of getting hurt.

Many runners fear that loose legs run slower. There is a finding behind it. Among 34 international distance runners, the least flexible were the most economical. Economical means they used less oxygen at the same speed. Stiff tendons may give back more of each stride.

But long holds seem to change your muscles, not your tendons. Researchers pooled the studies of people who held a muscle at the end of its range for weeks. The muscle got a little less stiff. No change in the tendon was found. So yoga should give you range and leave your spring alone.

You do not drop a session for it. Add five to ten minutes to the sessions you already do, on most days.

Before a swim or a run, keep moving. Reach overhead, turn your chest from side to side, and step through deep lunges without holding them. After a long ride, arch your back, round it, and turn it to each side.

Hold poses only once the day's fast work is done. After a long or hard run, sink into a low lunge. It opens the front of the hip the way your back leg opens it in a stride. Then press back into a downward dog. Go as far as you can while your breath stays calm.

Then give range a session of its own each week, and balance another. Where each one goes in the week is in How to schedule yoga around endurance and strength.