London, Nov 4 : Stretching before exercise can be bad for individuals, warn scientists, who found that the integral part of any athlete's warm-up routine can actually weaken muscles.
It has long been believed that the habit of holding a stretch for 20 to 30 seconds, known as static stretching, is beneficial for priming muscles.
But now, in a new research, scientists from the University of Nevada Las Vegas say this should no longer be encouraged.
Their findings highlight that the two common pre-running stretches - for the hamstrings and quadriceps - may actually reduce performance by weakening muscles in the leg.
"Developing flexibility is important for reducing sports injury, but the time to stretch is after, not before, performance," the Telegraph quoted Kinesiology professor Bill Holcomb, who authored the report, as saying.
Other studies have found that this stretching decreases muscle strength by as much as 30 per cent. Stretching one leg's muscles can also reduce strength in the other leg as the central nervous system can rebel against the movements.
The correct warm up, according to experts, should do two things - loosen muscles and tendons to increase the range of motion of various joints, and warm up the body.
To raise the body's temperature, a warm-up should begin with aerobic activity, and researchers recommend light jogging.