Do not fear the stretch
Stretching has been used for many decades as an exercise preparation and mobilisation tool. Recently it has been scrutinised for reducing athletic performance, particularly when used pre-competition or before strength training.
Luckily, there has been extensive research on this topic and, despite conflicting evidence, the wider scientific consensus remains that athletes should NOT fear stretching.
In this article we will filter the fallacies and reduce the prevalence of stretchphobia throughout the athletic community.
“Bro, don’t stretch! You won’t be able to bench as much…”
Athletes tend to shy away from stretching before resistance training sessions due to research suggesting it reduces force production…
Yes, research has shown dampened high threshold motor unit activation and maximal power output after long bouts of static stretching (1,2). This suggests that stretching has a negative effect on force production and alters the neural pathways responsible for maximal muscle contraction. Stretching also increases parasympathetic nervous system activity – a physiological responses not conducive for neurologically demanding training (3).
However, further investigation has debunked this school of thought.
The neural inhibition caused by static stretching is transient and will dissipate several minutes after the stretch is completed. Moreover, when combined in a dynamic warm-up, all stretch-induced strength loss is mitigated and neural drive returns to baseline (1,2). This means that the physiological response to an effective warm-up will cancel out the any stretch-induce strength loss.
All evidence considered, it would indeed be sensible to avoid long-duration (>120 seconds) static stretching before resistance training sessions.
Dynamic stretching on the other hand has no negative impact on force production and can be used to mobilise tissue and joint structures pre-training. In fact, dynamic stretching increases agonist muscle excitability and post-activation through activation of muscle spindles and assists neural readiness (4).
That said, static stretching is still a viable option…
It is dangerous to indulge in sweeping generalisations such as “never static stretch before weight training.”
Static stretching produces viscoelastic changes in muscle tissue and increases compliance of the muscle-tendon units (1). This is helpful for solving muscle imbalances in athletes who struggle to meet the mobility demands of resistance exercises. Lessening the extent of an athlete’s mobility issues pre-training reduces the likelihood of overloading an improper movement pattern during strength training (4).
“It Increases injury risk…”
Stretching and injury risk has been a hot topic for many years.
Proponents of stretching argue that it reduces muscle strain risk by improving force production at long muscle lengths and increasing resistance to excessive muscle elongation during dynamic movement. Opponents of stretching say it increases the likelihood of injury in sports that involve explosive power-based movements or require the athlete to produce force at short muscle lengths whilst under load (5).
This debate is a product of the inevitable tug-of-war between mobility and stability.
On the one hand, stretching increases muscle tissue compliance and joint range of motion, allowing the athlete to resists forces when in a stretched position. Conversely, excessive range of motion (or hypermobility) during explosive tasks (e.g. heavy lifting or plyometric drills) increases injury risk to joint structures (5).
Thus, functional range of motion is the goal!
There needs to be a balance between tissue compliance (intrinsic flexibility brought about by stretching) and tissue rigidity (or joint stability) that is specific to the athlete and his/her sport and training demands.
For example, a hurdler (who must flex the leading hip and extend the leading knee while simultaneously abducting the trailing leg to clear each hurdle) will have vastly different mobility demands to a shot-putter.
If a hurdler fails to acquire sufficient hip and hamstring flexibility through stretching, he/she will be exposed to heightened muscle strain risk when absorbing force at long muscle lengths (e.g. landing). Conversely, a shot-putter will need less flexible hamstrings as he/she generates force at shorter muscle lengths and is not exposed to the same movement demands as the hurdler (6).
If these two athletes were to swap stretch routines, they would both increase their muscle strain risk and reduce force production capacity during sport movement (5,6).
Therefore, the stretching dose is dependent on the individual athlete and his/her sport requirements. When prescribed correctly, stretching will prevent injury, not cause it.
“It reduces athletic performance…”
Let’s step out of the weight room.
Stretching is also said to negatively impact on-field performance. Some studies have shown reduced vertical leap and sprint ability after an acute bout of static stretching (7). This raises the question of its impact on rate of force production (RFP) during dynamic movement.
Stretching impacts RFP through two mechanisms:
Neural inhibitory effects: Extended periods (>10 seconds) of muscle stretching reduces afferent input to the motor neuron pool leading to lowered spinal reflex excitability. In turn, this will impact the contractile elements within the muscle tissue and reduce the speed and magnitude of muscle contraction (1,7).
Viscoelastic changes: Stretching causes mechanical deformation of the muscle-tendon unit making it more compliant to elongation. This response leads to altered muscle fibre length-tension relationships and increases the optimal joint angle of force production. Increased compliance of the muscle-tendon unit means that the tendon requires more time to be stretched before producing force and thus has reduced capacity to transmit force quickly to the bone (1,8).
Why is this not cause for major concern?
As discussed earlier, the negative impacts to force production are transient and easily mitigated (2).
Reductions in the amplification of neural drive will have an acute effect on RFP. So yes, this means holding a 90 second hamstring directly before completing a vertical leap test is not the best idea. However, if completed 10 mins before any explosive movement, the neuromuscular inhibitory effects of static stretching will be negligible (1,2).
Changes in muscle tendon stiffness may impact explosiveness if the athlete fails to complete static stretching in combination with a warmup (2). For that reason, it is recommended that static stretching completed during the warm-up is combined with muscle activation exercises and dynamic warmup drills which prepare muscle tissue for the movement demands of the upcoming session.
Don’t miss out on the benefits of static stretching people!
A well-planned stretch routine will solve muscle imbalances and promote movement efficiency. This involves treating postural issues, resolving strength exercise technique breakdown and skilled sport movement optimisation. Improved movement economy reduces both acute and overuse injury risk and enhances energy efficiency. Over time, a structurally balanced athlete will have greater probability of enjoying long-term injury resilience and career longevity (5).
“You shouldn’t include static stretching as a warm-up…”
Dynamic stretching is seen as the gold standard pre-sport-participation stretching modality (7).
However, static stretching is also a viable option.
Static stretching is best completed at the start of a warmup routine when combined with myofascial release and banded traction mobility drills. This offers a more potent form of tissue mobilisation for athletes with particularly severe mobility deficits (9).
Considering the time constraints associated with static stretching, the literature suggests prioritising muscle groups that are historically prone to muscle strain within a specific athletic population (5).
For example, Australian Rules Footballers are prone to rectus femoris and hamstring tears and therefore need to increase the muscle fibre length of these muscles pre-training and pre-match to accommodate to the sport demands. This could be achieved through static hip flexor stretching and banded hamstring mobilisation drills before conducting a dynamic warmup and sport specific drills.
Do not fear the stretch!
- Stretch-induced strength and RFP loss are transient and easily mitigated.
- Stretching treats muscle imbalance and promotes movement economy.
- Increased tissue compliance increases force production at long muscle lengths.
- Stretching reduces risk of muscle strains at long muscle lengths.
- Simic, L., Sarabon, N. and Markovic, G. (2012). Does pre-exercise static stretching inhibit maximal muscular performance? A meta-analytical review. Scandinavian Journal of Medicine & Science in Sports, 23(2), pp.131-148.
- Trajano, G., Nosaka, K. and Blazevich, A. (2017). Neurophysiological Mechanisms Underpinning Stretch-Induced Force Loss. Sports Medicine, 47(8), pp.1531-1541.
- Inami, T., Shimizu, T., Baba, R. and Nakagaki, A. (2014). Acute Changes in Autonomic Nerve Activity during Passive Static Stretching. American Journal of Sports Science and Medicine, 2(4), pp.166-170.
- Behm, D. and Chaouachi, A. (2011). A review of the acute effects of static and dynamic stretching on performance. European Journal of Applied Physiology, 111(11), pp.2633-2651.
- McHugh, M. and Cosgrave, C. (2009). To stretch or not to stretch: the role of stretching in injury prevention and performance. Scandinavian Journal of Medicine & Science in Sports.
- Alonso, J., McHugh, M., Mullaney, M. and Tyler, T. (2008). Effect of hamstring flexibility on isometric knee flexion angle-torque relationship. Scandinavian Journal of Medicine & Science in Sports, 19(2), pp.252-256.
- Hough, P., Ross, E. and Howatson, G. (2009). Effects of Dynamic and Static Stretching on Vertical Jump Performance and Electromyographic Activity. Journal of Strength and Conditioning Research, 23(2), pp.507-512.
- Gurjão, A., GonÇalves, R., de Moura, R. and Gobbi, S. (2009). Acute Effect of Static Stretching on Rate of Force Development and Maximal Voluntary Contraction in Older Women. Journal of Strength and Conditioning Research, 23(7), pp.2149-2154.
- McMillian, D., Moore, J., Hatler, B. and Taylor, D. (2006). Dynamic vs. Static-Stretching Warm Up: The Effect on Power and Agility Performance. The Journal of Strength and Conditioning Research, 20(3), p.492.