Regular Stretching Can Increase Weight Training Gains

Introduction
The value of stretching has been somewhat controversial. While there is no doubt that stretching is necessary for athletes whose limbs go through extreme ranges of motion in their sports (e.g. hurdlers, gymnasts) there is little evidence that it benefits other athletes. Regular stretching has not been shown to reduce the incidence of injuries among runners, and static stretching done right before "explosive" activities like jumping and sprinting actually impairs performance (although not next-day performance). However, a recent study by Kokkonen et al. in  the Journal of Strength and Conditioning Research (vol 24, no 2, 2010, pages 502-506) indicates that regular static stretching can actually increase weight training gains, at least for the first several weeks of a training program.

Experimental Procedure
Group 1 - Performed 3 sets of 6 repetitions of knee extension, knee flexion, and
               leg press 3 days per week (Monday, Wednesday, Friday) for 8 weeks
Group 2 - Performed the same weight training routine as Group 1 but also did a stretching
               routine twice a week (Tuesday, Thursday) consisting of 15 stretches for the hamstrings,
               quadriceps, aductors, abductors, external and internal rotators, planter flexors, and dorsiflexors.
               Each stretch was done for 3 sets of 15-second holds with 15 seconds of rest in between sets.

Results
Group 1 improved in knee flexion, knee extension, and leg press max lifts by 12, 14, and 9% respectively, while Group 2 improved 16, 27, and 31% respectively. For the latter 2 lifts, improvement was significantly greater for group 2.

Bottom Line
A static stretching routine performed Tuesdays and Thursdays can increases strength gains obtained from weight training on Mondays, Wednesdays, and Fridays, at least during the first several weeks of a training program.