The best way to prevent muscle strains is to perform a warm-up before participating in sports or vigorous physical activities. A warm-up should always be done before stretching because warm muscles are more elastic. Examples of effective warm-ups are light jogging, skipping, or riding a stationary bike. Taking 5 to 10 minutes before sports activities to warm up is a general guideline. If the weather is cold, a longer warm-up may be necessary. Stretching alone, before participating in sports, will not prevent injury. If your goal is to increase flexibility, a regular stretching routine is necessary (see chapter 10). If your goal is to prevent muscle strains before sports or vigorous physical activities, your best bet is to perform a gradual and thorough warm-up that includes a stretch.