Stretching and Strength Training
It has been
often said that strength training decreases flexibility because the muscle get stiffer from the high loads placed upon them. Static stretching can help increase flexibility but performed before strength training it reduces strength and stability. Dynamic stretching, in contrast to static stretching, has been shown to be an effective and safe method to warm up prior to strength training, and is also an effective method to increase flexibility in beginners. However, what effect does dynamic stretching have on strength training effects and does strength training really decrease flexibility? To find out the effects of stretching on strength training, scientists from the University of Rio de Janeiro started the following study.
What did the researchers do?
For this study, 28 women who had at least 36 months of experience with strength and flexibility training were recruited and randomly divided into four groups. One group only performed strength training (Strength). One group only performed stretching (Stretching). The last group performed strength training first and finished with stretching (Strength + Stretching) and the last group performed stretching first and finished with strength training Stretching + Strength).
The subjects were tested on strength using a 10 repetition maximum test (10RM) in the bench press and leg press exercises. The subjects performed flexibility tests as wel by using a sit and reach test.
After finishing measurements, all subjects started with the 12 week training protocol. The subjects trained on alternating days and subjects had to complete at least 44 training sessions in order to participate in the end measurements. Professional trainers oversaw all training sessions.
| Strength Training | Stretching | |
| Exercises | Leg Press, Leg Extension Leg Curl, Bench Press,Front Lat Pulldown, Seated Shoulder Press, Biceps Curl, Triceps Pulley | Dynamic stretching exercises involving upper and lower limbs, shoulders, hips and trunk. |
| Month 1 | 3 sets of 8-12RM 1min rest | 3 sets of 30 repetitions |
| Month 2 | 3 sets of 6-10RM 1min rest | 3 sets of 30 repetitions |
| Month 3 | 3 sets of 10-15RM 1min rest | 3 sets of 30 repetitions |
Figure 1: Strength training and Stretching protocols.
What were the results?
Figure 2: Effects on 10RM Bench Press Strength in kg.
Figure 3: Effects on 10RM Leg Press Strength in kg.
Figure 4: Effects on Sit and Reach Test Distance in cm.
There were no significant differences in any group in flexibility in the Sit and Reach test. All groups except the Stretching only group improved Bench Press strength significantly. The Strength Training group improved more than the two groups that included stretching, but this difference was not significant. All groups including the Stretching group improved their Leg Press strength. The Strength Training group improved their Leg Press strength significantly more than the Stretching group.
What did the researchers conclude?
Including dynamic stretching has no negative impact on strength training results.
The order of strength training and dynamic stretching does not influence training results.
Strength training does not decrease flexibility.
What does this mean for me?
-Strength training does not decrease flexibility, even if you are quite flexible already like the subjects in this study.
-Adding flexibility exercises in the form of dynamic stretching does not hinder strength development.
-If you are already quite flexible, adding dynamic stretching to strength training does not increase flexibility.
See also:
-Effects of stretching on strength training
-Top 5 Static stretching fables