Should You Stretch Before Exercise? A Data-Driven Answer
Although it is a practice all fitness enthusiasts undertake, stretching before intensive exercise has often been an underlooked topic of interest.
We all know that preparing oneself physically before working out is essential, to prevent injury and to perform at our peak level.
We often scrutinise how to perform our workouts most efficiently, to get the best results we could obtain.
Rarely, however, do we scrutinise our warm-up and stretching routine.
This article aims to shed some light on what the scientific literature has to say about stretching as a means for an effective pre-workout warm-up, to improve performance and reduce the risk of injury.
What is stretching?
Stretching has been a technique used for thousands of years. It has been a part of the most primitive forms of exercise, from yoga (which evidence suggests has been present for at least 1,200 years) to the first Olympic games in 1896, to modern era professional sports.
Stretching is merely a technique of moving a joint or muscle with a goal to elongate or lengthen the muscle.
The goal of stretching before resistance training is to try to put the muscle through its full range of movement (ROM), to prepare for specific exercises which may put significant stress on the joints and soft tissues in the area, thereby making the muscles more flexible before strenuous activity.
With that umbrella definition it’s also worth knowing there are essentially 3 ways, or types, of stretching, that people perform:
- Static stretching – this is the type of stretching that involves holding the desired muscle in one stretched position for a period of time. For example, sitting on the floor, reaching forward to touch your toes with your legs straight, and holding still for 10 seconds.
- Dynamic stretching – this is the type of stretching that involves actively moving a joint or muscle to produce a muscle stretch but not holding that muscle in the stretched position. An example is standing and running on the spot while bringing your knee to touch your hands at chest height.
- Proprioceptive neuromuscular facilitation (PNF) stretching – this technique uses the principle of reciprocal inhibition to stretch a muscle. This involves stretching a muscle as you usually would, and then exerting force against the opposite direction of the stretched direction. This forces the required muscle to relax (as one muscle contracts, its opposing muscle group has to relax) for a few seconds and continuing to apply more of a stretch in the required direction.
Stretching and flexibility
Harvey et al conducted a meta-analysis to see if stretching did improve Range of Movement (ROM) in people without any significant contractures.
The study looked at thirteen studies in total, however, nine were deemed ‘poor’ quality studies, so the results obtained were from the resulting four studies which were deemed ‘moderate’ quality.
The results found that stretching did improve the range of joint movement for people without functionally significant contractures.
This finding was mimicked by Page et al who found all of the three types of stretches we discussed earlier in this article improved ROM, with a further conclusion that ‘PNF-stretching may be more effective for immediate gains’.
If we look at one of the most commonly tight group of muscles we see in our Crawley physiotherapy clinic, the hamstrings, a review by Decoster et al (which looked at multiple studies totalling 1,338 healthy subjects) found that multiple types of stretching techniques result in an improved range of movement in the posterior thigh muscles.
So the evidence does seem to suggest that stretching of multiple types, especially PNF, does have a positive impact on the ROM of joints and muscles.
Stretching, performance injury prevention
So we know now that stretching does improve ROM but does this have any impact on injury prevention and our performance as athletes? As this is ultimately the reason we stretch.
A study in 2013, published in the Journal of Strength and Conditioning Research by Gergley looked at the ‘one rep max’, or 1RM, for healthy individuals completing a barbell squat.
The study looked at 17 men aged 18-24 who underwent two supervised pre-workout routines; the first was an active dynamic warm-up and the second was the same but followed by lower body passive static stretches (PSS).
The study noted:
“A significant decrease in 1RM (8.36%) and lower-body stability (22.68%) was observed after the PSS treatment.”
Small et al found previous to this when assessing four different randomised controlled trials that static stretching was ‘ineffective in reducing the incidence of exercise-induced injury’ and McHugh et al reports there is ‘an abundance of literature demonstrating that a single bout of stretching acutely impairs muscle strength’.
This is consistent with a large systematic review conducted by Kay et al in 2012 which looked at a total of 106 studies found that static stretching can negatively impact muscle performance when the stretches are held for over 60 seconds.
Furthermore, a meta-analysis of 104 studies between 1996 and 2010 by Simic et al which looked at the impact of pre-exercise static stretching (SS) on strength, power and explosive muscular performance concluded that ‘…the usage of SS as the sole activity during warm-up routine should generally be avoided’.
Kistler et al found that static stretching, even after a period of dynamic warm-ups is harmful in sprinters of distances up to 100m.
That being said, the same results were not always found for those who underwent dynamic or PNF-style stretching.
When comparing active dynamic stretching (ADS) to a static passive stretch combined with ADS (SADS), and static dynamic stretch combined with ADS (DADS), Fletcher et al found that track and field athletes have a significantly worse 50m sprint time when completing the SADS intervention as compared to the ADS and DADS groups (which showed non significant changes in performance), indicating the active and dynamic portion of stretching counteracts the negative aspects of passive static stretching.
While studying leg extension power, Yamaguchi et al found that dynamic stretching resulted in significantly improved power when compared to non-stretching, even though static stretching had no impact on performance.
Manoel et al confirmed this when studying muscle power in women and concluded:
“The findings suggest that dynamic stretching may increase acute muscular power to a greater degree than static and PNF stretching.”
The research suggests that stretching, whether it is in a passive/static or active/dynamic manner has a positive impact on range of movement, but this does not necessarily translate to improved performance or reduction in the risk of injury.
The research to date suggests that static stretching before exercising may increase your risk of injury and reduce your performance, especially muscular power.
However, the research also suggests that dynamic and sport-specific stretching before exercising may increase muscular power and performance, and reduce the risk of injury.
Therefore it is recommended at present to undergo a dynamic and exercise-specific stretching regime before an intense workout routine.