What does science say about stretching?

Stretching and strength training are often seen as two distinct components of a fitness routine, each with its own benefits. But what happens when these two approaches are combined? Can stretching enhance strength, or does it compromise performance? And how do these practices influence long-term physical development?

In this article, we’ll explore the science behind stretching and its relationship with strength training. Drawing from recent research and studies, we’ll explore how stretching impacts muscle performance, flexibility, and growth, both in the short term and over time. Whether you're an athlete, coach, or fitness enthusiast, understanding the interplay between these two elements can help optimize your training strategy for better results.

Article: The effects of stretching on strength performance

By Ercole C Rubini 1, André L L Costa, Paulo S C Gomes

Strength and flexibility are important parts of exercise, but it's unclear how to combine them effectively in one program. Many people stretch before strength training, believing it prevents injuries, reduces soreness, or improves performance. However, recent research shows there's little scientific proof for these claims.

Studies reveal that stretching, especially for long durations, can temporarily reduce strength. These decreases are more noticeable when stretching routines are longer or more intense than typically recommended. This suggests that more research is needed to align stretching protocols with real-world practices.

When including stretching in a workout, it's important to consider safety, avoid increasing injury risks, and not spend unnecessary time on overly long routines. Further investigation is needed to fully understand how stretching impacts strength and performance.

For more information, read the full article.

Research: Chronic Effect of Static Stretching on Strength Performance and Basal Serum IGF-1 Levels

By Carmen L Borges Bastos 1, Humberto Miranda, Rodrigo Gomes de Souza Vale, Maria de Nazaré Portal, M Thiago Gomes, Jefferson da Silva Novaes, Jason B Winchester

This study looked at how static stretching affects strength and a growth-related hormone (IGF-1) during a 10-week strength training program. It involved 30 volunteers who were divided into three groups:

1. SBST Group: Did static stretching as a warm-up before strength training.
2. SDST Group: Performed static stretching during the strength training session.
3. OST Group: Did no stretching at all.

Findings:

• Muscle Strength: All groups improved strength, but the group without stretching (OST) had the most significant gains across all exercises. The groups that stretched (SBST and SDST) only showed noticeable strength improvements in some exercises.
• IGF-1 Levels: Only the OST group showed a significant increase in IGF-1, a hormone linked to muscle growth, by the end of the program.

Conclusion: While stretching doesn’t prevent strength gains, skipping it entirely during strength training appears to lead to better results in muscle strength and IGF-1 levels.

For more information, read the full research.

Study: Acute effect of a ballistic and a static stretching exercise bout on flexibility and maximal strength

By Reury Frank Pereira Bacurau 1, Gizele Assis Monteiro, Carlos Ugrinowitsch, Valmor Tricoli, Leonardo Ferreira Cabral, Marcelo Saldanha Aoki

This study compared the immediate effects of two stretching techniques—static and ballistic—on lower-limb strength and flexibility in 14 physically active women. Participants completed three sessions:

1. Control Session: Measured leg press 1-repetition maximum (1RM) without any stretching.
2. Ballistic Session: 20 minutes of ballistic stretching before the leg press 1RM test.
3. Static Session: 20 minutes of static stretching before the leg press 1RM test.

Findings:

• Static Stretching: Strength decreased significantly (from 213.2 kg to 184.6 kg), but flexibility improved more than with ballistic stretching.
• Ballistic Stretching: Strength was unaffected, maintaining performance levels similar to the control session.

Conclusion: Static stretching is not ideal before activities requiring maximum strength, as it reduces force output. Ballistic stretching, however, seems to preserve strength and may be a better choice for warm-ups before strength-demanding activities.

For more information, read the full study.

Articles: To stretch or not to stretch: the role of stretching in injury prevention and performance And The use of static stretching in warm-up for training and competition

By M. P. McHugh 1, C. H. Cosgrave and By Warren B. Young accordingly

Both articles explore the role of static stretching in warm-up routines and its impact on performance and injury prevention. Research consistently shows that SS can acutely impair muscle performance, particularly strength, prompting a reevaluation of its use before training or competition. However, its influence on injury prevention remains less clear. While static stretching appears to have little effect on overuse injuries, there is some evidence that it may reduce the risk of muscle strains, though further high-quality studies are needed to confirm this.

A major challenge in interpreting these findings is the lack of consistency in research methods, such as variations in stretching volume, intensity, and how static stretching interacts with other warm-up components like sport-specific drills or dynamic exercises. Both articles highlight the importance of optimizing warm-up protocols to balance performance and injury prevention, with an emphasis on tailoring routines to individual fitness levels, skill requirements, and the specific demands of each sport. Future research should focus on standardizing methodologies and exploring the time course of stretching effects to refine warm-up strategies.

For more information, read full article #1 and full article #2

Report: The Effects of Stretching on Performance

By Peck, Evan MD; Chomko, Greg DPT; Gaz, Dan V. MS; Farrell, Ann M. MLS

This article reviews the effects of different types of stretching—static, dynamic, and proprioceptive neuromuscular facilitation (PNF)—on athletic performance. It categorizes performance into three domains: strength and power, speed and agility, and endurance. The literature from studies published between 2003 and 2013 was analyzed, excluding research focused solely on joint range of motion or injury prevention.

Key Findings:

1. Static Stretching:

• Strength and Power: Static stretching before strength and power activities often impairs performance, including activities like countermovement jumps and 1RM lifts. However, with adequate time (e.g., 15 minutes) or a subsequent warm-up, the negative effects may be reduced.
• Speed and Agility: Static stretching generally reduces sprint speed and agility performance. The baseline flexibility of an athlete may influence this effect.
• Endurance: The effects of static stretching on endurance are inconclusive, with some studies showing negative impacts and others no effect.

2. Dynamic Stretching:

• Strength and Power: Dynamic stretching generally improves performance in strength and power activities, such as countermovement jumps. It may also enhance performance when combined with a general warm-up.
• Speed and Agility: Dynamic stretching enhances speed and agility, improving sprint and agility test times. However, excessive volume may lead to fatigue and impair performance.
• Endurance: There is insufficient evidence to determine the effect of dynamic stretching on endurance performance.

3. PNF Stretching: Limited research on PNF stretching suggests it has a minimal or no effect on performance.

Conclusion:

Static stretching, particularly when done immediately before an activity, generally has a negative impact on strength, speed, agility, and endurance. Dynamic stretching, on the other hand, tends to enhance performance in strength, power, and speed/agility activities but may lead to fatigue if performed excessively. Further research is needed, especially regarding PNF stretching and its effects on performance across various sports.

For more information, read the full report.