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The Dynamic World of Stretching: Can it Prevent Injuries? 🏃‍♂️💪

The Dynamic World of Stretching: Can it Prevent Injuries? 🏃‍♂️💪

Justas Muzikevicius
November 12, 2023

Sports Med U | Educating Minds, Elevating Potential

Potential Effects of Dynamic Stretching on Injury Incidence of Athletes: A Narrative Review of Risk Factors

Behm, D.G., Alizadeh, S., Daneshjoo, A. and Konrad, A., 2023. Potential Effects of Dynamic Stretching on Injury Incidence of Athletes: A Narrative Review of Risk Factors. Sports Medicine, pp.1-15.

In today’s letter

Overview of the Potential Effects of Dynamic Stretching on Injury Incidents
Analogy for dynamic stretching affects on the body
Rapid Results = This narrative review concludes that dynamic stretching may have beneficial effects on knee kinematics, the muscle-tendon junction morphology & athletes’ readiness to compete, but not on ROM, performance & balance/proprioception
Professional takeaway = The benefits outweigh the risks of dynamic stretching, thus no reason not to include it in practice.

Bite-size study - Infographic style!

Deeper look

Aim of study

The aim of this narrative review was to examine existing research on injury rates when dynamic stretching or dynamic activities are included in a warm-up routine before physical activity.
Additionally, the authors explored potential factors that could influence these injury rates, including ROM, strength, balance, proprioception, muscle structure, and psychophysiological responses.

Background info

It’s suggested that static stretching can negatively impact performance in both the stretched muscle and the opposite non-stretched muscles.
Previous reviews and original research studies have shown that when static stretching is limited to no more than 60 seconds per muscle group and is included within a comprehensive warm-up that includes prior aerobic activity, as well as subsequent dynamic stretching and activity, the effects on subsequent performance are generally minimal
Dynamic stretching involves controlled movements within the active ROM, characterized by repetitive muscle loading (tension during end ROM) and unloading (muscle relaxation through mid-ROM)
Some studies suggest that a single session of static stretching may be more effective than dynamic stretching in enhancing ROM, although there is varying research on this topic

Methods

The authors located just 2 studies that specifically examined how dynamic stretching by itself impacts the occurrence of injuries.
Because there weren't enough studies for a systematic review or meta-analysis, the authors opted for a narrative review.
This allowed a broader range of information to be explored without being bound by the strict methodologies and structures typically required for systematic reviews.

Results/Discussion

ROM

In the existing research, there's an ongoing debate about how reduced flexibility might influence the likelihood of getting injured.
Some review articles emphasize that flexibility and measures of ROM are significant indicators that can predict injury rates, while others have raised doubts about ROM being a risk factor for injuries

Kinematics

It's important to investigate how dynamic stretching affects body movements (kinematics) because previous studies have linked kinematics to the risk of injuries, especially in the lower limbs.
While most studies primarily focus on how dynamic stretching impacts flexibility and ROM, a handful of research projects have delved into how dynamic stretching affects the way the lower limbs move during activities like football instep kicks and landings.
Some evidence suggests that dynamic stretching can potentially alter how the knee moves during landings, specifically by reducing knee abduction (sideways movement) and internal rotation (inward twisting).
However, we don't have a complete understanding of the underlying mechanisms. Even though these findings indicate a generally positive impact of dynamic stretching on joint movements, more research is needed in various dynamic tasks to reinforce these conclusions

Effects of dynamic stretching on performance

Increasing the muscle-tendon complex's ability to handle forces, especially when muscles are stretched (which is where most muscle-tendon injuries occur), could reduce the risk of injuries with such a mechanism
A meta-analysis found that a single session of dynamic stretching had a positive impact on performance in various activities like jumps, sprints, agility, and strength tests in 20 studies, with small or greater improvements.
However, it had trivial effects in 21 studies and even impairments in 7 studies. On average, these improvements were small, totaling about 1.3%.
The improved performance seen after acute dynamic stretching in some studies can be attributed to several factors, including increased muscle and body temperature, which enhances energy production, improved neuromuscular function due to dynamic stretching effect on spindle reflexes and motor neurons, stimulation of the nervous system, and reduced inhibition of antagonist muscles. Additionally, post-activation potentiation may enhance the rate of muscle contractions.
Interestingly, many of these factors can also be achieved with the more limited ROM involved in many dynamic activities. This raises questions about whether performing dynamic movements throughout a full ROM (as seen in dynamic stretching) is necessary to reap these benefit

Balance & proprioception

It's well-established that impaired balance and proprioception are among the various factors linked to the risk of injuries.
In two studies where participants did a single session of dynamic stretching, minor improvements in balance were observed. These improvements were seen when participants stretched the quadriceps, hip flexors, gastrocnemius, and hamstrings, and then underwent balance tests such as the Y-balance test and Star Excursion Test.
When a separate study applied acute dynamic stretching to both upper and lower limb muscles, there was no significant impact on participants' balance. This test used a stability platform, which restricts the balance assessment to a single plane of motion.
Another study focusing on the quadriceps, hamstrings, and gastrocnemius muscles also found no balance improvement when evaluating centre of pressure during a demi-pointe pose.

The results regarding the immediate effects of dynamic stretching on balance and proprioception appear conflicting. Since there are no studies that have looked into the long-term effects on balance and proprioception, this remains a significant research question for future investigations.

Morphology

Dynamic stretching may offer potential benefits in reducing the risk of injuries, possibly by decreasing muscle-tendon junction (MTJ) stiffness. This change in MTJ stiffness can occur due to muscles and tendons becoming more flexible.
When the MTJ becomes more flexible or less stiff, it can better absorb energy during physical activities, potentially reducing the severity of muscle soreness.
Some researchers have suggested that the increase in ROM following a single session of dynamic stretching is primarily due to improved stretch or pain tolerance rather than a reduction in soft tissue stiffness.
In cases of chronic dynamic stretching training, reported increases in MTJ compliance can alter the angle-torque relationship. This change allows for greater relative force production at longer muscle lengths, which could contribute to injury prevention by enhancing dynamic joint stability. Since many injuries occur when muscles are in lengthened positions where force is naturally reduced, this shift towards greater force outputs with elongated muscles may offer protection against muscle strain injuries.
Once again, there is conflicting evidence regarding how dynamic stretching affects MTJ stiffness, both in the short term and with chronic training. In various studies, dynamic stretching has resulted in decreased stiffness, no change, or even increased stiffness in muscles/MTUs. Consequently, based on the available evidence, it's challenging to draw a definitive conclusion about whether dynamic stretching-induced alterations (or the absence of alterations) in MTJ stiffness and compliance can prevent injuries.

Psychological factors

Dynamic stretching might have mental benefits for athletes, and this could be due to psychological factors
It may have a positive impact on psychosocial stressors and influence emotional states, leading to potential improvements in psychophysiological aspects like reduced muscle tension, enhanced concentration or focus, and better mental readiness for games and competitions.

Clinical use

This research paper only looked at two studies, thus we don’t have a firm grasp of the affectedness or in-effectiveness of dynamic stretching on injury prevention
Notably, injury risk reduction hinges on raising body temperature and the activation of the nervous system to put it simply
Established protocols like FIFA11+ have demonstrated efficacy in reducing injuries among football players and thus can be a good guide for developing simpler plans (FIFA11+ takes about 25min to complete)
Furthermore, the psychological readiness of athletes should not be underestimated, as bolstering confidence plays a pivotal role in enhancing athletic performance and injury reduction.
In conclusion, the benefits outweigh the risks and thus it may be beneficial to use a couple of dynamic stretching exercises in the dynamic warm-up, however, the focus should be on position control, body temperature rise and sport-specific movement under dynamic motion.