Stretching Before Exercise

The idea here is that stretching before and after you exercise can prevent injury while you’re working out and muscle soreness afterward.

While stretching does promote flexibility (something you should strive for as an element of overall fitness), a study published in British Medical Journal found no scientific evidence to back up the notion that stretching before a workout reduces injuries or that stretching before and after can prevent muscle soreness.
Exercise Speeds Metabolism for Hours

While partly true--your metabolism does amp up during exercise and for a few hours afterward--the truth can be a big disappointment: the number of calories you can expect lose thanks to the afterburn is negligible, only 20 extra ones for the whole day according to one study.

But (and this is a really big “but”) you may be able to set your metabolism on high for hours after your workout if you can exercise intensely enough to reach the top of your VO2 max (the maximum amount of oxygen you can take in during exercise) and continue at that high level for 45 minutes. A tough prescription, but if you can manage that, a recent study found that you could burn as many as 190 extra calories in the hours after exercise.

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