A: Results of long term studies with healthy humans between the age 21 and 39 have shown that after 6 weeks, the people who stretch thirty seconds per muscle every day were able to increase their mobility more than the people that stretched fifteen seconds per muscle per day. Changes in mobility amongst those that stretched for fifteen seconds per muscle per day were statistically insignificant. People that stretched sixty seconds per muscle per day increased their range of motion but not significantly more than those that held their stretches for thirty seconds.Other studies have shown that people can increase their range of motion using only 15 second stretches while others gain very little increased mobility with even 45 second stretches. How long to stretch appears to vary depending on which muscle groups are being stretched but on average
studies show that its beneficial to hold a stretch for between 15- 60 seconds 3 times.