The importance of rest September 16 2015, 0 Comments
Browsing through YouTube the other evening, I came across Dr James O'Keefe, a cardiologist, delivering a talk on TED, in which he advises against overdoing exercise, a rather unexpected comment to come from a cardiologist. He compares exercise to a drug - a fantastic drug that protects against heart disease, diabetes, depression and a multiple of other conditions. However, as with all drugs, it has an optimal dose range, and if you overdo it, it can do more damage than good.
The human body is a remarkable piece of apparatus. It improves by a process of damage and repair. When you exercise beyond your limit, micro-tears develop in your muscles, and when these are repaired, the muscle is built back stronger and better than before. This is the process of getting fit, and it requires a period of rest before exercise is repeated to allow the repair to take place, or the tears simply get bigger. The heart is a muscle like any other, and according to Dr O'Keefe, sustained exercise beyond about an hour results in micro-tears or damage. If you take some rest days afterwards, these repair themselves, better and stronger than before.
The issue comes with long-term, long-distance runners who train regularly enough for the repair process not to take place. Their hearts stretch to accommodate the sustained increased blood that they pump, and the tears do not repair so that scar tissue is formed. He cites a study of some 50'000 people which shows that runners have a 19% longer life expectation than sedentary people, but that when they run over 30km average a week, this benefit cancels out. The result also applies to speed - up to 10km/h provides benefit, but pushing to 12km/h sees it go away. Finally, running two to five times a week provides the benefit, but running seven days a week takes it away again. The Copenhagen Heart Study, tracking 20'000 people since 1976, confirms these results. Joggers have a 44% lower mortality rate and live on average 6 years longer than non-runners - provided they run at a slow to average pace for one to two-and-a-half hours or two or three times per week.
Some of you will always prefer to run far and fast and die happy. With these learnings you can choose your own destiny and the good news is that if you choose to change and slack off now, the heart repairs itself and returns to normal. For the rest of us, exercise is a remarkable therapy, and running up to 30k per week at a moderate pace will make us healthier and happier. You can find Dr O'Keefe's talk here. Good running all!