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 Although athletes and coaches often swear by stretching, many common
pre-workout routines may not actually enhance performance, said lead
author Matt McCrary, a master’s degree candidate at the University
of Sydney.
Higher load dynamic warm-ups are "the best bet" in most situations,
said McCrary. For the upper body, these include push-ups, dumbbell
back flys, and resisted lateral raises, he told Reuters Health by
email.
Dynamic stretches focus on getting the blood flowing and increasing
range of motion by using multiple muscle groups simultaneously.
Unlike static stretches, which generally involve holding a single
pose for a minute or two, dynamic stretches use a series of
controlled movements.
To analyze the effect of upper body warm-ups, McCrary and colleagues
reviewed findings from 31 past studies.
The review, published in the British Journal of Sports Medicine,
included 628 people playing sports at many levels, from youth
leagues to college athletics and adults in recreational activities.
Most studies involved sports where upper body strength is essential,
such as baseball, football, tennis, golf, kayaking and shot put.
The review found that high-intensity dynamic stretching improved
strength and flexibility while delaying muscle soreness.
But low-intensity stretching had little effect on performance, which
agrees with previous research on upper body warm-ups, McCrary said.
“Flexibility increases are generally unrelated to any type of
performance improvements,” he noted.
Heating and cooling during a warm-up also does little to improve
performance, the study found. While applying heat to specific
muscles before strenuous activity may minimize the loss of
flexibility in the days following the workout, this practice didn’t
show other benefits.
And for baseball players, batting warm-ups didn’t work as well when
bats were much lighter or heavier than those used during games.
“This runs somewhat contradictory to the prevailing narrative that
higher load warm-up is better than lower load warm-up,” McCrary
said. “The two theories here are that warm-up swings with a heavier
weight bat significantly and sub-optimally alter swing mechanics
and/or that a resisted movement longer in duration than a baseball
bat swing is necessary to produce a warm-up effect.”
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While high intensity dynamic stretching can help elite and
professional athletes, the same warm-ups may not be a good idea for
more casual exercisers, said Dr. Kazuki Takizawa, an associate
professor of sports training science and exercise physiology at
Hokkaido University in Japan.
“Warm-up exercises may reduce injury by improving performance for
serious athletes,” Takizawa said in an email. “But recreational
athletes and weekend warriors are at a lower physical fitness level,
especially in aerobic capacity, and they may fatigue by warm-up
exercise and reduce performance.”
Takizawa also made a distinction between endurance sports like
long-distance running or cycling and more intense activities done
for shorter periods.
“Short-term, high intensity exercises need vigorous warm-up,”
Takizawa said. “But long-term endurance exercises do not.”
Because the study didn’t look specifically at injury prevention,
it’s impossible to say for sure how intense dynamic stretching or
other warm-ups might affect the risk for injuries, McCrary said.
“We haven’t really zeroed in on what kinds of warm-ups best prevent
injuries,” he said. “Anecdotally, I feel like warm-ups definitely do
play a role in injury prevention, however, further study is required
before I’d be able to confidently make any recommendations or
explain how or why this is the case.”
SOURCE: http://bmj.co/18VhZAH British Journal of Sports Medicine,
online February 18, 2015.
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