The benefits of stretching to reduce injury and improve performance are only partially supported by research, according to a report in The Physician and Sportsmedicine journal.

What to stretch, for how long, and why are still up for scientific debate.

In a recent study, doctors checked the medical database Medline and the sports science database SPORTDiscus for articles on stretching. They found that only one post-exercise stretch of 15 to 30 seconds per muscle group is needed for most people, although some people or muscle groups may need more.

If the stretches are intended to relieve post-exercise aches, additional stretching may provide greater benefits, according to the study.

One of the benefits of stretching is in the mind. Increasing stretch tolerance reduces feelings of pain for the same force applied to the muscle, according to the report.

Stretching before exercise isn't as valuable as you might think, researchers reported. An active warmup such as jogging is more effective in decreasing injuries.

If preventing injuries is your primary objective (safety and health pros take note), and the range of motion necessary for an activity is not extreme, the evidence suggests that you should drop stretching before exercise and increase warmup, according to the article.