Research shows that if the physical activity includes explosive or bouncing movements, such as basketball, volleyball, and plyometric exercises (exercises that include a lot of jumping and bounding), stretching can reduce injuries by increasing the compliance of your tendons and improve their ability to absorb energy. However, for low-intensity activities that don’t include bouncing movements, like running, cycling, and swimming, stretching doesn’t prevent injuries because you don’t need very compliant tendons for those activities.
In regard to the type of injury, stretching can prevent muscle injuries, such as sprains and strains, but not bone or joint injuries. Bone and joint injuries, which are common among runners, are caused by increasing running volume or intensity too quickly for your body to adapt.
Stretching before or after you run also has a minimal effect on how sore you feel after your workout. When you run harder or longer than you’re used to, microscopic damage occurs to your muscle fibers, which is a normal part of training. In response to the muscle fiber damage, you get inflammation as more blood travels to the site, bringing with it white blood cells to start the healing process. You feel sore a day or two after a hard workout because of the damage-induced inflammation, which is called delayed-onset muscle soreness (DOMS). Stretching doesn’t make your muscle fibers heal more quickly, so stretching won’t make you feel less sore. Only time and good nutrition, including lots of healthy protein and carbohydrate, reduce soreness as your muscle fibers heal.
MYTH: LACTIC ACID CAUSES FATIGUE, MUSCLE BURNING, AND MUSCLE SORENESS.
There has never been any experimental evidence proving a cause-and-effect relationship between lactate and fatigue. Although lactate increases when running fast, so do other metabolites, including potassium ions, hydrogen ions, ADP, and phosphate, all of which cause fatigue in different ways. Because of lactate’s concomitant increase with these other metabolites and the simple method of measuring its concentration in the blood, scientists use lactate as an indirect measure of acidosis.
Lactate also doesn’t cause muscle burning, which may be related to acidosis and the increase in muscle temperature that occurs when you run fast.
Finally, muscle and blood lactate return to pre-exercise levels within 30 to 60 minutes after you run, so lactate is long gone by the time you feel sore. Muscle soreness occurs from microscopic tears in the muscle fibers from training and the subsequent inflammation.
MYTH: STRENGTH TRAINING WILL MAKE YOU A BETTER DISTANCE RUNNER.
There is little evidence that strength training improves distance running performance. Distance running is primarily limited by the delivery and use of oxygen. There are no studies showing that strength training increases the supply of oxygen to and use by muscles, which is largely dictated by cardiac output, the amount of red blood cells and hemoglobin, and muscles’ capillary and mitochondrial densities. However, when done to increase power, strength training can improve running economy.
Jason Karp, PhD
Run-Fit, LLC
Jason Karp, PhD, is the owner of Run-Fit, LLC, 011 IDEA Personal Trainer of the Year, and creator of the REVO2LUTION RUNNING certification. He has more than 200 published articles in international running, coaching, and fitness magazines, is the author of six books, including The Inner Runner, and speaks around the world. For training programs and autographed copies of his books, go to http://run-fit.com
