Some exercise myths are just benign half-truths, but many others can actually be harmful. They can cause frustration in keeping people from reaching their goals and sometimes even lead to injury.

Most of the perpetuation of these myths comes from TV and magazines selling a product, or from old, outdated methods that have become so entrenched they are hard to change. Some are more obvious and have been dispelled long ago but somehow keep hanging on.

Of course, the health and fitness field is rife with myths, but in our view these 10 are the most misleading, the most enduring, and the most common, starting this week with Nos. 10 and nine:

Myth 10

Stretching before activity prevents injury.

No. Performing static stretching before activity does not appear to prevent injury in most studies over the past 10 years. And more recent studies have even shown that static stretching before power lifting actually decreases the amount lifted compared to doing no stretching at all. It is amazing how many athletes that come in to see us for injuries tell us that they do static stretches before a practice or a game but nothing afterward. Athletes and exercisers are often in a hurry to leave the gym, field or ice after their session and often skip the stretches.

Instead what they should be doing before play is five to 10 minutes of heating the body with dynamic, cardiovascular movements (running, skating, etc).

That will make the muscles and tendons more pliable and helps to prepare the nervous system for sport-specific movements during play. Then after the game or practice, that’s the time to do your static stretching holding still for at least 20 to 30 seconds for each stretch. Stretching after the activity is what increases flexibility, prevents long-term muscle tightness and helps to reduce the chances of injury.

Myth 9

Time of day matters. You don’t burn more calories or get a better workout first thing in the morning compared to late in the evening, or vice versa. People often feel more awake or like they get a better workout at either end of the day, but there is no appreciable difference at the tissue level. Running five kilometers burns the same number of calories no matter when you do it. It is true that circadian rhythms, hormonal variations and temperature changes do occur through the day, but your body adapts once you get into a routine. Studies are inconclusive at this point, but a few have shown very small (less than five per cent) increases in strength, endurance and body temperature in the afternoon. But it’s not clear that this translates into a better workout for most people. A slightly lower body temperature in the morning or evening for instance can be easily eliminated with a proper warm-up. The best advice is to find the time of day that works best for you and stick to it.

One caveat to exercising first thing in the morning however. If you are going to do a very strenuous workout right after getting up, make very sure you warm-up sufficiently so your body is ready. Your muscles, joints and spinal discs are more susceptible to injury if they are not ready for intense exercise.

Likewise, eating late at night doesn’t make the food turn to fat. The misconception is that food that doesn’t get burned right away will convert to fat when you go to bed. But this is not true. Often when you eat at night you overeat because you are snacking on high-calorie foods or you didn’t eat a proper dinner and overeat because you are famished. Overeating is the thing that turns food calories to fat. As long as you don’t eat more calories than you burn during the day, the food you eat at night won’t turn to fat. Remember, even though your metabolic rate may slow down a little, it is still going all night long to repair your body from the day’s activities. That takes energy.

The list continues next column.

Kerry Senchyna holds a bachelor of science degree in kinesiology and is owner of West Coast Kinesiology in Maple Ridge (westcoastkinesiology.com).