Stretching: The Truth
For this week's CBS Doc Dot Com segment, I thought I'd cover something completely non-controversial: what can weekend warriors learn from elite athletes? But I'm starting to believe that in this era of evidence-based medicine, nothing may be truly knowable.
I went to the studios of the world famous Ballet Hispanico in New York City and spoke to athletic trainer Megan Richardson. She took me through the motions, emphasizing the importance of warming up and stretching in preventing injury. It sounded good and it felt good. But proving in the medical literature that it's effective is another thing. An online search quickly produced multiple conflicting reports and advice: stretching definitely works, stretching definitely doesn't work; stretching only works if you do it my way. Click here for a sampling:
PubMed:Warm-up And Stretching
PubMed: Stretching Perspectives
BioMed Central: The Effects Of Stretching
My friend and CBS colleague, Richard Schlesinger, offered his solution. "I get around it by neither stretching nor exercising." Had I listened to Richard, my blog would have ended right here. But I figured I needed at least one more paragraph so I contacted a true expert on the subject, Ian Shrier MD, PhD, a specialist in sports medicine and Associate Professor at McGill University. He has a PhD in physiology and is Past-President, Canadian Academy of Sport Medicine. He's not a huge fan of stretching right before exercise. "First, the stretching, whether with or without warmup, does not improve performance. It makes you run slower, jump not as high, and makes you weaker." And "stretching definitely can hurt people if you overstretch; people do it all the time if they force the stretch."
He added, "I don't think it hurts you in general if you do it properly but it doesn't prevent injury." He's more supportive of stretching at other times, including after exercise, saying, "Regular stretching at other times is beneficial. It makes you stronger, jump higher, etc, and there are three studies suggesting it reduces injuries as well, although the results were only significant in one." He adds that "stretching is analgesic; it allows you to put your muscle through a wider range of motion without feeling tension. And that may be why ballerinas say that stretching helps them." Dr. Shrier spells out his take on the subject in detail in a chapter called "Does stretching help prevent injuries?"
For me, Dr. Shrier's most interesting advice, especially for weekend warriors, was about the importance of warming up. He explained that muscles need energy to function properly. Energy is mainly produced inside of cells in structures called mitochondria. When you are resting, your mitochondria power down. During exercise, it takes awhile for the cell to rev up the enzymes needed for breaking down fat and carbohydrates for fuel and for using oxygen to make energy from that fuel.
If you start running at full speed without warming up, your body will produce lactic acid. Lactic acid can impair muscle function for awhile, preventing you from sprinting efficiently at the end of the race. So Dr. Shrier suggests gradually warming up. He estimated it takes about 3 to 5 minutes to efficiently go from one level of exercise to the next - for example, going from rest to a ten minute mile or going from a ten minute mile to a seven minute mile. If you go for a jog, "you walk, then jog slowly, and then pick up it up. Elite marathoners might go for a fifteen to twenty minute jog before they run a marathon. That allows them to run faster at the beginning of the race. They run the second half of the marathon faster than the first."
In summary - and I suspect that I am the first person today to tell you this - don't outpace your mitochondria.
For athletic trainer Megan Richardson's take on stretching and warming up, click
.