Lean in: The science of stretching
Feel inflexible and think a stretch will help? The benefits might not be as great as you think.
There are two extremes of flexibility: in one camp lie the lithe-limbed devotees of yoga or Pilates and in the other those who grunt when they bend to pick up something.
Most of us fall somewhere in between but are aware that if we don’t do something to offset the decline, touching our toes, even our knees, will become a distant memory.
Stretching seems the obvious choice, and yet scientists say how and when you stretch matters more than previously thought.
“We now realise that the traditional stretching of muscles and tendons is not a simple, blanket approach that is guaranteed to prevent injury and improve recovery,” says Dr Brendon Stubbs, senior clinical lecturer in physiotherapy at King’s College London.
In a recent review published in the journal Frontiers in Physiology, a group of exercise scientists in Portugal sifted through the available evidence on stretching to find out if and when we really need to do more of it. Their results showed that myths abound about its effects on flexibility and muscle health and that stretching has little or no impact on injury risk.
“Almost like a habit, stretching exercises are regularly included in warm-up and cooling-down exercises in virtually all formats of exercise,” Stubbs says. “
Yet we have all overestimated some of the benefits.”
It still matters, he says, but we need to understand the science of how to stretch well.
Is inflexibility inevitable from middle age onwards?
“As we get older our muscles do change in size and strength,” Stubbs says. “Both muscles and adjoining tendons that provide the connection to our bones become less supple and consequently less flexible.”
A gradual reduction in general movement beyond middle age – along with too much sitting – doesn’t help with this physiological downturn in flexibility.
In a paper published in the journal Sports Medicine the Australian exercise scientist James Nuzzo argued that a mix of resistance training, aerobic activity involving whole body movement – swimming, walking, running – and moving more are probably more helpful than just stretching in offsetting age-related decline in flexibility.
“The message is that the older we get the more attention we should pay to maintaining our flexibility,” says Dr Lewis Macgregor, a lecturer in physiology and nutrition in sport at the University of Stirling. “Stretching is part of the equation, but maintaining muscle strength and aerobic fitness are as important.”
How often should you stretch?
“The effects of a stretch are pretty short-lived,” Macgregor says. “About 10-15 minutes after stretching your muscles can be back at the point they started.”
If you start to stretch regularly then the cumulative effect will make post-stretch flexibility gains slightly longer-lasting.
“Stretch every day for two weeks and your muscles might stay flexible for 20 minutes and after a month it might be a few minutes more,” Macgregor says.
Permanent changes in the physical structure of muscles can take months, even years of dedicated stretching.
“Do a little every day as part of an overall activity plan. A couple of weekly yoga or Pilates classes will help, but are not enough to make big differences in the short term.”
How flexible do we need to be?
“It’s not a rule that we all need to increase the amount of stretching we are doing,” says Dr Dearbhla Gallagher, senior lecturer in sports therapy at Buckinghamshire New University. “You don’t need the same level of flexibility within the muscle for recreational walking as you do for professional ballet dancing.”
More flexibility is not always better.
“If you are very flexible or even hypermobile you may be at increased risk of injury from various types of sport,” says Stubbs. “Strength or plyometric work can reduce this risk more than stretching.”
Plyometric exercises, also known as jump training or plyos, involve explosive bursts of different movements to build muscle power, such as skater hops, box jumps, burpees and split squat jumps.
In some sports being too flexible means muscles don’t lengthen and shorten as efficiently as they should.
“With competitive weightlifting the more tense a muscle remains the more force it can exert,” Macgregor says.
There is evidence that runners who have higher amounts of stiffness in their leg muscles move more efficiently, their tightly coiled muscles acting as springs that store and return energy with every stride.
“You need the amount of flexibility relative to your lifestyle,” Gallagher says.
Should stretching be part of your warm-up?
Researchers at Edith Cowan University in Australia asked male athletes to hold nine static stretches for five seconds and the same stretches for 30 seconds another day. On a third day they performed the stretches dynamically and in a final session they did a gentle warm-up with no stretching. On each occasion they then completed a battery of fitness tests.
Results showed that performances didn’t change, regardless of stretching or not. According to the Portuguese team, a warm-up stretch is unlikely be detrimental but is definitely not obligatory.
“For now the answer to ‘Can I stretch in the warm-up?’ is ‘probably yes’,” they concluded. “But to the question ‘Do I have to stretch in the warm-up?’ the answer is ‘maybe not’.”
Do we need to hold a stretch?
Static stretching – holding a stretch for sometimes a minute or longer – has fallen out of favour with scientists after some researchers showed it might temporarily weaken the stretched muscle.
Holding a stretch causes minor damage inhibiting nerve contraction, which might mean muscles don’t fire properly when you sprint or lift weights.
“Stretching doesn’t have to be about holding a position for very long periods in muscles where you feel tight or sore,” Gallagher says.
If static stretching makes you feel good then hold the stretch for a shorter duration.
“Static stretching for 30 seconds or less is unlikely to have a negative effect before or after exercise,” Macgregor says. “But it’s not good practice to hold it for longer than 60 seconds and certainly not longer than 90 seconds before exercise.”
Will post-workout stretching speed up recovery?
Stretching as part of a cool-down seems to make sense. When muscles are warm they are more pliable and more responsive to stretching.
“You can stretch a bit further and your range of movement is slightly increased,” Macgregor says.
It certainly feels better to finish a workout with some gentle stretching and it is often prescribed by trainers.
However, the Portuguese team found no proof that it enhances recovery. In one of their previous studies, also published last year, they assessed the effects of post-workout stretching. Results showed that, when compared with rest or other recovery methods, such as low-intensity cycling, stretching offered no benefits in aiding muscle recovery. Stretch if you want to, but don’t expect miracles is Stubbs’s advice.
“A Cochrane gold standard review found that post-exercise stretching may reduce muscle soreness the next day by 0.5 points on a scale from 0-100,” he says. “Which is not very much at all.”
Should we lift weights instead?
Strength training can have huge benefits on flexibility.
“Because you are increasing the range over which you can produce large forces, your muscles become strong as well as flexible,” Macgregor says.
“The most effective way to stretch is to do core work, some strength work and plyometrics,” Stubbs says.
The Times
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