To stretch or not to stretch, what is the answer?

Stretching has long been considered a fundamental component of warm-ups and cooldowns for athletes and exercisers alike. Historically, it was thought to prevent injuries, enhance recovery, and improve performance. Additionally, flexibility has traditionally been recognized as a key component of physical fitness, further supporting the use of stretching in training programs. However, as research evolved, opinions diverged — some now view stretching as ineffective or even counterproductive, while others still consider it indispensable. This review aims to clarify the controversy by examining current evidence on stretching’s acute and chronic effects on performance, injury risk, recovery, and flexibility.

Brief definitions

Static Stretching
Static stretching involves lengthening the muscle until either a stretch sensation or the point of discomfort is reached and holding the muscle in a lengthened position for a certain period of time(1).

Dynamic stretching
Dynamic stretching involves doing a set of controlled, active movements through the range of motion of the active joint(s), without holding the movement at its endpoint. (1). It can be exemplified as arm swings, arm circles, and swinging the leg back and forth.

Flexibility
Flexibility is an intrinsic property of body tissues that determines the range of motion achievable without causing injuries(2).

Acute effects of stretching on range of motion and performance
An acute bout of both pre-exercise static or dynamic stretching has been found to increase flexibility and joint range of motion(1,3,4), but the effects of each stretching method seem to have different implications in terms of performance.

Static stretching
The effects of pre-exercise static stretching (SS) on performance have widely been studied. The large body of evidence suggests that pre-exercise SS can negatively affect strength and power performance(5–8). However, a clear dose-response relationship exists between the duration of stretching and its subsequent effects on performance where <60 seconds seems to have trivial negative effects compared with >60 seconds(1,9,10).

Dynamic stretching
In contrast to static stretching, dynamic stretching seems to be a preferable and more efficient as part of a warm-up routine(4,11). A recent systematic review, including 48 studies, showed that dynamic stretching revealed a trivial to small performance enhancements(1).

Effects of incorporating static and dynamic stretching to a full warm-up routine
In a study by Fletcher el. al(12), the combination of static and dynamic stretching resulted in significant performance decrements in sprint time. However, recent evidence suggests that, when included in a full warm-up routine, static stretching (<60 sec) alone or incorporated with dynamic stretching does not lead to subsequent performance decrements(13,14). Interestingly, there’s evidence suggesting that the inclusion of a sports-specific warm-up can attenuate the negative effects of static stretching, with studies reporting either no change or performance enhancement (15,16).

Effects of stretching on delayed onset muscle soreness and muscle recovery
Evidence from systematic reviews suggests that stretching, whether conducted before and/or after exercise, doesn’t significantly reduce delayed onset muscle soreness (DOMS)(17–19). In terms of muscle recovery, most studies failed to show any benefits of stretching(20,21), and one study(22) suggested that stretching might actually inhibit recovery. Accordingly, evidence from meta-analyses comparing different recovery methods found that stretching does not have a significant overall effect on DOMS and the recovery of muscle function(23). Also, a recent meta-analysis on this topic failed to show any beneficial effect of stretching on DOMS and fatigue(24).

Effects of stretching on injury risks
In the history of scientific literature, stretching has always been promoted in pre-activity exercises as a method to prevent injuries. In the last two decades, many systematic reviews and experimental studies challenged this claim and showed that stretching has no effects on injury incidence. However, looking into the quality and the methodology of these studies raises several questions regarding the efficacy of stretching in injury prevention.

Theoretically, a decrease in muscle stiffness or an increase in muscle compliance following an acute bout of stretching may decrease the risk of injury(25). An earlier systematic review in 2002 found no association between stretching and injury risks(18). Accordingly, another systematic review in 2008, along with 2 meta-analyses in 2014 and 2020 (the latest meta-analysis was limited to military personnel), found that static stretching does not reduce over-all injury rates(26–28).

However, one of the reviews mentioned above by small et al. (2008)(26) suggests that despite the general findings not showing that static stretching significantly reduces over-all injury rates, it’s important to note that static stretching may have a positive effect on reducing the risk of musculotendinous and ligament injuries.

Several issues make it more challenging to draw definitive conclusions from the reviews above. One main issue is the inclusion of a relatively low number of randomized clinical trials (from 2 to 4 studies) and the difference in methodology between studies. Additionally, the two studies by Pope et al. are often cited in these reviews and other reviews accessing the effects of stretching on injury risks(29,30). A key problem with these two studies is the prescribed stretching duration (20 sec), which may be not enough to induce a meaningful decrease in passive resistance to stretch(25).

In the next section, we will discuss and highlight the limitations of the Randomized Clinical Trials cited in the reviews mentioned above.

In an attempt to resolve this controversy, an extensive systematic review by David Behm (1) found no effects of stretching on overall injury rates. However, after splitting the type of sports and its related injuries, the authors found that pre-activity stretching can reduce muscle-related injuries (commonly among sprinters). In contrast, no effects were found in terms of overuse injuries (typically among endurance athletes). In this review, among the 12 studies included, 8 studies showed some effectiveness of stretching, and 4 studies showed no effect, and there was no evidence that stretching increases injury risks. After splitting the type of sports and its related injuries, the author found only 2 of the 5 studies included showing a benefit of stretching in endurance sports or military training, which involves overuse injuries. However, in sprint running type sports, 5 out of the 6 studies showed fewer injuries with stretching.

The effect of stretching on injury rates is a vast area that needs further research. The available evidence doesn’t seem to support the efficacy of stretching on overall injury rates. However, pre-activity stretching may reduce the incidence of muscle-related injuries commonly found among sprinting sports. 

Can we increase flexibility in ways other than stretching?
The effects of stretching on flexibility are universally agreed and generally supported through various studies(34–36). Nonetheless, resistance training has been shown to increase flexibility in both young and elderly individuals(37–40). Accordingly, one study noted similar increases in flexibility between groups allocated to either a static stretching program or a full-range- resistance training program(41). Finally, a systematic review of 6 studies found strong evidence that eccentric training effectively increases lower limb flexibility(42). Resistance training includes a variety of machine-based exercises targeting the lower limb muscles (quadriceps, hamstrings, and calf muscles); all these exercises are performed eccentrically in a slow controlled manner or using Isokinetic dynamometers (knee flexion, knee extension, leg press, hip flexion with the knee extended and heel drops). This increase in flexibility, following eccentric training, is more likely attributed to a process called “sarcomerogenesis” or adding sarcomeres. However, it is essential to consider whether the individual is able to safely perform the movement through its full range of motion before expecting such adaptations to occur. For example, Romanian deadlifts can significantly improve hamstring flexibility when executed with proper technique and full range of motion—but if the individual lacks the mobility or control to hinge effectively, the expected flexibility gains may not be achieved.

Nevertheless, for resistance training to meaningfully improve range of motion (ROM) in a specific joint action, the exercises must be performed through the full available ROM. For instance, if the goal is to increase shoulder extension limited by biceps tightness, incline dumbbell curls can be performed on a bench angle that allows the elbows to extend behind the torso. Conversely, if the restriction originates from the anterior deltoid, front dumbbell raises on an incline bench may be used, gradually reducing the incline as shoulder extension improves.

Flexibility and risk injuries.

Hypermobility (an increase in the range of motion beyond normal limits) have been shown to increase the risk of lower extremity injuries in “recreational” ballet dancers(43). In addition, hypermobility increases the risk of knee injuries during contact activities(44). Accordingly, lack of flexibility (below normal levels) has also been shown to increase the risk of injuries. In a systematic review, people with reduced ankle range of motion had nearly five times the ankle sprain risk compared with an average range of motion(45). Finally, a recent systematic review found that there is “moderate” evidence supporting the association between flexibility (ankle and hamstring) and musculoskeletal injury risk, but the direction of association wasn’t stated(46).

Takeaway message

An acute bout of both dynamic and static stretching can increase range of motion.

Long duration pre-exercise static stretching (≥ 60 seconds) can lead to detrimental effects on performance.

Short duration pre-exercise static stretching, especially when combined with a full warm-up and sport-specific activities, has no detrimental effects on performance.

Dynamic stretching is preferable to static stretching during a warm-up.

Stretching doesn’t seem to have a significant influence on delayed onset muscle soreness and muscle recovery.

Stretching doesn’t seem to reduce the risk of overall injuries, but it may reduce the incidence of muscle-related injuries.

Resistance training and especially eccentric training are considered effective ways of increasing flexibility.

Low levels of flexibility are probably due to low physical activity, and levels of flexibility can be maintained, restored, or improved with exercises that have other secondary benefits that stretching doesn’t achieve(47).

Finally, personal preferences should be considered, and it’s important to note that many people enjoy stretching, so if you are one of those people, just keep doing it. If you are not involved in some high-level athletic competitions, and you feel more prepared doing some stretches pre-workout, then go ahead and static stretch.

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