I grew up believing that if I didn't wait an hour after eating before swimming, I might cramp up and drown. My track coach told me a steak was the best meal I could have before a race. Those were commonly held beliefs in the 1960s that didn't hold up to scientific study.

I have always believed that if science says its true, it must be so. Recently, however, I read The First Twenty Minutes by Gretchen Reynolds, who writes the "Phys Ed" column for the New York Times, examining the most current information about exercise practices. The results were often surprising.

Does stretching help performance?
As a coach, I spent many years beginning my practices by putting my junior high and varsity running teams through a stretching program. The idea was to loosen their muscles and help them run better races. But studies using college runners have showed that those who stretched before races performed worse than those who didn't. Comparing the best race times among athletes revealed that the least flexible runners, those with the tightest muscles, tended to be the fastest and athletes who stretched had more injuries.

Easy running warm ups and relaxed muscle exercise that mimic the race activity are helpful though. So throwers go through throw motions, hurdlers go through hurdler motions and so forth. These activities loosen the muscles and increase the range of motion.

Is running bad for your knees?
Anyone who runs after the age of 40 will have people advising them that they will ruin their knees. Recent studies don't bear out this belief. While individuals who suffered a traumatic injury to the knee or have poor biomechanics may have to quit running when they get older, examinations of those with healthy knees, shows years of running does nothing to injure joints.

Studies which compared two groups, one of older runners and others who didn't run, tracked these individuals for more than two decades until most were in their 70s and 80s. They found that while 32 percent of the nonrunners had arthritis, only 20 percent of the runners did. The hypothesis going in had been that the pounding would lead to more arthritis. The result was those that ran regularly had healthier knees and were continuing to run well into advance age.

How best to recover from hard workouts?
"Delayed onset muscle soreness" or DOMS occurs hours or a day after strenuous exercise. It is actually a good thing as this is how tissue strengthens and adapts to physical stress. Athletes have tried various strategies to try and minimize the discomfort that sets in after hard exercise. A series of studies were done to try and determine the best means of recovery.

In one study runners upon completing a difficult workout were divided into two groups. One did nothing and the other walked slowly on a treadmill with a slight incline. It was thought that those who didn't cool down would not recover as fast. The results showed that there was no difference between groups in reported rates of muscle stiffness.

To reduce inflammation and sore muscles we have been told to take ibuprofen. In a poll of runners competing in the Western States 100 Mile, competitors who took ibuprofen were just as sore during and after the event as those who didn't take it. In laboratory experiments conducted on animal tissues, ibuprofen slowed the healing of injured muscles, tendons, ligaments and bones.

After completing long runs in the spring and fall, I used to wade into a lake thinking that the icy water would reduce muscle inflammation. And there were occasions when I would apply ice wrapped in a towel to sore legs. Scientifically, however, there is little to support these practices. Personally, the chill of the lake water and ice did take my mind off my stiffening muscles.

While I don't mind giving up icing as a recovery strategy, I do enjoy massages. After having athletes do strenuous arm exercises, Canadian researchers had one group of athletes lay quietly for ten minutes while the others received ten minutes of massage by certified sports massage therapists. The thought was that the massage would remove the buildup of lactic acid, which is believed to contribute to post-exercise soreness. This study reinforced what other tests had shown: Massage impedes, rather than moves, blood to tired muscles and kneading muscles does not speed recovery. It should be noted that this doesn't mean that massage has no benefits. It just means that we don't know what the benefits are.

For most of us, getting a massage sure feels good. And that may be a factor in recovery. While there may not be tangible benefits to practices like stretching, cool downs, icing or massage, if an athlete feels they must do them, the psychological benefits may outweigh the negatives.

Research has shown that the best means of recovery is rest. After a hard workout, the best way to ease muscle pain or stiffness might come from doing nothing. If the soreness lingers, take a second day off. This is most applicable for those hardcore athletes who are practitioners of the "no pain no gain" and "feel the burn" school of exercise. Those who take an easier approach to exercise probably don't need to take days off.

How much exercise do we need?
All studies point out that some exercise is better than none, but there is no consensus as to exactly how much is optimal. However, a massive study in 2008 called "Physical Guidelines for Americans" concluded that 150 minutes per week of light exercise like walking or easy cycling as being about the right amount. If easy jogging was done, then about half as much time was needed.

People who go from not exercising to working out, see a tremendous improvement in health. Compared to sedentary individuals, those who exercise 150 minutes a week cut their risk of dying prematurely by nearly 20 percent. If someone triples the amount they exercise to an average of about 90 minutes a day, their risk of premature death drops further but only by about 4 percent.

Does exercise prevent cancer?
Moderately intense physical activity is more effective than less strenuous activity in the prevention of cancer. This finding came from a study involving 2,560 Finnish men who kept records of their daily activities for 20 years. The incidence of gastrointestinal or lung tumors in men who exercised intensely for 30 minutes a day was 50 percent less. The occurrence of colon cancer is less among those who exercise briskly perhaps because this speeds the emptying of the colon.

Although our beliefs about best practices in exercise keep evolving as the results of the latest scientific studies come to light, it is safe to bet that regular doses of physical activity are good for us.

Dave Foley recommends reading Gretchen Reynold's book as this feature only highlights a fraction of the material available.