Effects of Strength Training and Flexibility training on Each Other

Introduction

Both strength and flexibility are important for sport performance. In masters athletes both strength and flexibility decrease with age and so become even more important for the competitive masters athlete.

Strength training either by lifting heavy weights or in circuit training has been shown by previous research to improve flexibility. In 2011, a study either doing strength or flexibility training simultaneously or by themselves for 16 weeks and found that strength training also improved both strength and flexibility. However, some research has shown that strength performance when doing weights can be reduced if you do flexibility training beforehand.  The aim of this study was to analyze the strength and flexibility gains after 12 weeks of combined or isolated strength and dynamic flexibility training by experienced older women who had at least 3 years of both strength and flexibility training behind them.

The Research

Twenty-eight trained women (age = 46 ± 6 years; body mass = 57 ± 5 kg; height = 162 ± 5 cm) were randomly divided into 4 groups of 7 people per group: strength training (ST), flexibility training (FLEX), combination of strength and flexibility (ST + FLEX), and combination of flexibility and strength (FLEX + ST). All groups were assessed before and after training for the sit and reach test, goniometry-range of motion about joints, and 10 repetition maximum in bench press and leg press exercises. The training protocol for all groups included training sessions on alternate days and was composed of 8 exercises performed at periodised (gradually increasing) intensities. The FLEX consisted of dynamic stretching performed for a total duration of 60 minutes.

The Results

The results demonstrated significant strength gains in all groups in the leg press exercise. All groups except the FLEX improved in bench press strength with no statistical differences between groups. However, effect sizes ( a measure the size of any changes in measures) demonstrated slightly different effects of training on strength measures for each group. The largest effects on strength measures were calculated for the ST group and the lowest effects in the FLEX group. Both combination groups (ST + FLEX and FLEX + ST) demonstrated lower effect sizes for both leg press and bench press as compared with the ST group. No significant differences in any of the flexibility measures were seen in any group.

So What?

These findings suggest that combining strength and flexibility is not detrimental to flexibility development. However, combined strength and flexibility training may slightly reduce strength development, with little influence of order in which strength or flexibility exercises are performed. For me, both types of training are important for masters athletes. So whatever of the two you want to emphasise is the one you need to emphasise when training the two together in one session.

For more details on strength and flexibility training for masters athletes, check out chapters 7 (Strength training for masters athletes) and 9 (Flexibility training for masters athletes) of my book at: http://www.mastersathlete.com.au

Source: Leite, T. and others (2015) Influence of strength and flexibility training, combined or isolated, on strength and flexibility gains. Journal of Strength and Conditioning Research, 29(4): 1083-1088.