Static stretching vs Eccentric loading

There are a few relevant studies available that actually compare static stretching with eccentric loading for flexibility, but they all conclude the same thing; both result in significant improvements in flexibility, but there is no significant difference between the two interventions.

The first study to examine these effects was by Nelson and Bandy (2004). They observed a significant improvement in hamstring flexibility following static stretching and eccentric training, compared to a control group over 6 weeks. There was however no significant difference between both groups despite a slightly greater increase following eccentric training. The major flaw to this study was that at the end of the eccentric movement, a 5 second hold was performed. This could be considered a static stretch, which questions whether eccentrics alone would be as beneficial.

Nelson was also involved in a further study in 2006, examining the immediate effects of the same interventions. This time, there was no hold at the end of the eccentric movement. After a total of 30 seconds under load (6 sets of 5 second reps), compared to a 30 second stretch, the eccentric group showed the greatest, most significant increase in flexibility. This response is likely due to the temporary changes in viscoelastic behaviour (O’Sullivan et al 2012). This therefore would support using eccentrics prior to an event if you needed a short-term increase in flexibility.

Both studies by Nelson were performed in high school students, with the latter involving athletes only. Caution must therefore be taken when applying the results to the general population due to the specificity of the population involved.

The most recent study by Askar et al (2015) compared eccentric loading with static stretching and dynamic stretching for hamstring flexibility, whilst also including a control group. Each intervention group contained 22 participants each, performing 1 session a day for 3 days, over a 6 week period.

The results showed that eccentric loading provided the most effective intervention for improving flexibility of the hamstrings, however there was no significant difference between this and static stretching. Both the eccentric and static stretching group were significantly more effective than dynamic stretching and all three provided significant benefits over the control group.

The limitations with the study are that it was performed in regular footballers aged 18-25. This makes it hard to generalise for the whole population, due to the majority of patients being older and more deconditioned. It also follows the usual theme from these studies, in that the participants are not in any pain. They also all only looked at the hamstring muscle. As mentioned in the previous post, this may be due to the perceived importance of hamstring flexibility (American College of Sports Medicine 2018).

An interesting area for more research would be the effects of eccentric loading for frozen shoulders. The current physiotherapy recommendation for frozen shoulders is for stretching and manual therapy, but with a lack of positive results (Uppal et al 2015). Due to the hypo-algesic effect of exercise and the perception of safe movements reducing muscle guarding (Naugle et al 2012), eccentric loading could have a positive effect.

Adam Meakins (2015) has written a blog around the area which can be found here. Unfortunately, there is a lack of research for eccentrics in the upper limb for flexibility, with none looking at frozen shoulder.

From the current available evidence, there appears to be no difference between stretching and eccentric training for improving flexibility. Due to the additional benefits from strength training, would it not make more sense to make the muscles strong as well as long?

As with all research, interventions should be applied to the patients on an individual level though. It is still common for some patients to believe that stretching is a key component to their fitness regime. If they have previously benefitted from stretching, then the belief of the effects can be very powerful (Munnangi and Angus 2019).

Also, there may be patients that struggle with eccentric training due to fatigue and pain (Shokri et al 2018). Eccentric training is associated with post exercise soreness – so should be used in caution and with education with certain patients. If loading eccentrically is too painful for a patient and flares up their symptoms, stretching may be more suitable to achieve greater flexibility.

How important is flexibility though? If the only benefits to static stretching are to improve flexibility, why is this important to us? The next blog will question if flexibility is still as important as previously thought.

References:

American College of Sports Medicine. ACSM’s guidelines for exercise testing and prescription. 10th ed. Philadelphia: Wolters Kluwer; 2018.

Askar, P et al (2015). Effectiveness of eccentric training, dynamic range of motion exercises and static stretching on flexibility of hamstring muscle among football players. International journal of physiotherapy, [online] 2 (6), pages 1012-1018. Available at: https://www.researchgate.net/publication/285746053_EFFECTIVENESS_OF_ECCENTRIC_TRAINING_DYNAMIC_RANGE_OF_MOTION_EXERCISES_AND_STATIC_STRETCHING_ON_FLEXIBILITY_OF_HAMSTRING_MUSCLE_AMONG_FOOTBALL_PLAYERS [accessed 31st December 2020].

Meakins, A (2015). Frozen shoulder? Let it go, let it go…. [blog]. The Sports Physio. Available at: https://www.thesports.physio/2015/11/18/frozen-shoulder-let-it-go-let-it-go/ [accessed 10^th January 2020).

Munnangi, S and Angus, L (2019). Placebo effect [online]. Florida, StatPearls publishing. Available at https://www.ncbi.nlm.nih.gov/books/NBK513296/. [accessed 7th January 2020].

Naugle, K et al (2012). A meta-analytic review of the hypoalgesic effects of exercise. Journal of the American pain society, 13 (12), pages 1139-1150.

Nelson, R (2006). A Comparison of the Immediate Effects of Eccentric Training vs Static Stretch on Hamstring Flexibility in High School and College Athletes. North American journal of sports physiotherapy, [online] 1 (2), pages 56-61. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2953312/ [accessed 4th January 2020].

Nelson, R and Bandy W (2004). Eccentric Training and Static Stretching Improve Hamstring Flexibility of High School Males. Journal of athletic training, [online] 39 (3), pages 254-258. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC522148/ [accessed 4th January 2020].

O’Sullivan, K et O’Sullivan, K et al (2012). The effects of eccentric training on lower limb flexibility: a systematic review. British journal of sports medicine, [online] 46 (12), pages 838-845. Available at: https://www.ncbi.nlm.nih.gov/pubmed/22522590 [accessed 10th December 2019].

Shokri, P et al (2018). Fatigue Induced Effects after Concentric versus Eccentric Exercises on Sense of Force and Senses of Position among Young Normal Adults: A Controlled Single-Blinded Study. Journal of research in medical and dental sciences, 6 (3), pages 258-267.

Uppal, H et al (2015). Frozen shoulder: a systematic review of therapeutic options. World journal of orthopaedics, [online] 6 (2), pages 263-268. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4363808/ [accessed 5th January 2020].

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