Dynamic and static stretching on hamstring flexibility and stiffness: A systematic review and meta-analysis

Area of Science:

• Sports Medicine
• Biomechanics
• Exercise Physiology

Background:

• Hamstring injuries are prevalent in sports, often linked to reduced flexibility and increased stiffness.
• Dynamic stretching (DS) and static stretching (SS) are common warm-up methods to enhance flexibility.
• The comparative effects of DS and SS on hamstring flexibility and stiffness require clarification.

Purpose of the Study:

• To conduct a meta-analysis comparing the short-term, medium-term, and long-term effects of DS and SS on hamstring flexibility and stiffness.
• To evaluate the impact of different stretching protocols on range of motion (ROM) and muscle properties.

Main Methods:

• A systematic meta-analysis of randomized controlled trials (RCTs) was performed.
• Studies were sourced from major databases (PubMed, Cochrane, Web of Science, PEDro) up to July 2022.
• Methodological quality was assessed using the PEDro scale, with data analyzed using random or fixed effects models.

Main Results:

• Across 27 RCTs (606 participants), single bouts of SS and DS yielded similar acute improvements in hamstring ROM and length.
• Multiple SS sessions demonstrated superior acute and sub-acute improvements in hamstring ROM compared to DS.
• Long-term effects showed SS to be more beneficial than DS for hamstring ROM, with no significant medium-term differences.
• Limited evidence exists for hamstring stiffness, with conflicting results between DS and SS.

Conclusions:

• Single sessions of DS and SS offer comparable short-term improvements in hamstring flexibility and length.
• Repeated SS interventions are more effective than DS for enhancing hamstring ROM over time.
• Further research is needed to definitively compare the effects of DS and SS on hamstring stiffness.