Does Resistance Training Improve Flexibility?

Stretching is often the go-to for improving flexibility. This new meta-analysis explored if resistance training is effective at improving joint flexibility and the findings might surprise you.

Overview

• What did they test? A systematic review and meta-analysis were conducted to evaluate the effect of resistance training (RT) on joint flexibility in healthy adults. The analysis included 36 studies with 1,469 participants. 
• What did they find? Resistance training tended to produce a moderate improvement in joint flexibility, especially after high-intensity training protocols. However, substantial variability and a high risk of bias were found across studies. 
• What does it mean for you? While resistance training tended to improve joint flexibility, particularly after high-intensity training protocols, inconsistency in study methods and a high risk of bias limit definitive conclusions. More research is warranted to better understand the effect of resistance training on flexibility.

What’s the problem?

Flexibility can be defined as the ability to move a joint through its full range of motion. While stretching is a common practice to improve joint flexibility, limited research suggests resistance training might be just as effective 1. A previous meta-analysis from Alizadeh and colleagues 2 reported comparable improvements in joint flexibility from resistance training and stretching. However the researchers didn't include training variables like intensity, volume, or frequency as moderators in their analysis which can influence the effects of resistance training.

Purpose

The purpose of this study was to evaluate the effect of resistance training (RT) on joint flexibility in healthy adults and to assess the influence of various factors (study-, sample-, and intervention-level variables) on the outcomes. 

Hypothesis

The authors hypothesized that resistance training alone can increase flexibility compared to a control condition. Additionally, they posited that isolated resistance training interventions would have a greater effect on older or sedentary individuals than younger or active individuals.