The Influence of Strength Training on Joint Flexibility

A systematic review, meta-analysis, and meta-regression.

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This systematic review, meta-analysis, and meta-regression by Favro et al. (2024) investigated the influence of resistance training on joint flexibility in healthy adults.

Key Points

Aim

The main objective was to evaluate the effect of resistance training (RT) on joint flexibility in healthy adults and assess the moderating effects of study-, sample-, and intervention-level variables.

Methods

• A systematic search was conducted across 9 academic databases.

• Inclusion criteria: healthy adult participants (≥18 years), resistance training intervention (≥4 weeks duration), and at least one flexibility outcome.

• Risk of bias was assessed using RoB-2 and ROBINS-I tools.

• A 3-level meta-analysis was performed, with multiple outcomes nested within each study.

• Moderator analysis was conducted using meta-regression.

Results

1. Overall Effect: The pooled effect size for resistance training on flexibility was g = 0.6325 (95% CI: 0.4762 to 0.7888, p < 0.0001), indicating a moderate positive effect.

2. Heterogeneity: There was substantial heterogeneity between studies.

3. Moderators:

   • Exercise intensity was a significant moderator (p < 0.0225), with high-intensity protocols showing a magnified effect compared to low-intensity.

   • Sex was also a significant moderator (p = 0.0429).

   • Activity level and age were non-significant moderators.

4. Risk of Bias: None of the included papers were at low risk of bias.

Practical Application

1. Resistance training could be implemented as a strategy to improve joint flexibility.

2. Heavy resistance training protocols may result in greater improvements in flexibility compared to low-intensity protocols.

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Related

Strength Training Improves Range of Motion, So You May Not Need to Stretch

Strength Training vs Stretching for Improving Range of Motion

Effects of Chronic Static Stretching on Strength and Muscle Hypertrophy

Does Heavy Strength Training Make You Tight?

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Key Takeaways

1. Resistance training has a moderate positive effect on joint flexibility in healthy adults.

2. The effect of resistance training on flexibility is comparable to that of stretching interventions, as noted in previous reviews.

3. The intensity of resistance training appears to be an important factor in determining its effect on flexibility.

4. The high risk of bias and substantial heterogeneity in the included studies limit the ability to draw definitive conclusions.

Limitations

1. There is a high risk of bias in all included studies.

2. Substantial heterogeneity between studies.

3. The review focused only on healthy adults, limiting generalisability to other populations.

This study offers important insights into the potential of using strength training to improve flexibility. However, the study quality and heterogeneity limitations suggest that further high-quality research is needed to confirm these findings and explore the underlying mechanisms.

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Reference

Favro, Francesco; Roma, Enrico; Gobbo, Stefano; Bullo, Valentina; Di Blasio, Andrea; Cugusi, Lucia; Bergamin, Marco. The Influence of Resistance Training on Joint Flexibility in Healthy Adults: A Systematic Review, Meta-analysis, and Meta-regression. Journal of Strength and Conditioning Research ():10.1519/JSC.0000000000005000, December 31, 2024. | DOI: 10.1519/JSC.0000000000005000