How regularly do you treat injured athletes with reduced lower limb flexibility? The answer from many of you would likely be all day long! It has been well established that athletes with reduced lower limb flexibility are at greater risk of injury (Murphy et al., 2003). Thus, it would be logical that a program of regular stretching, which has been shown to improve lower limb flexibility (Harvey et al., 2002), would reduce this injury risk… wouldn’t it? Well, not conclusively…
Stretching To Reduce Injury Risk?
As suggested above, you would think that improving flexibility via stretching would reduced injury risk. However, many studies have suggested that stretching (alone) is ineffective at reducing injury risk (Aaltonen et al., 2007; Herbert et al., 2002). How can this be? O’Sullivan et al. (2012) suggest that an altered length-tension curve, and not just reduced flexibility, is what may increase injury risk.
To explain this concept a little further consider the length-tension curve shown above. O’Sullivan et al (2012) has suggested that reduced flexibility increases injury risk secondary to inability of the muscle to produce adequate force in a lengthened position and exposes the muscle to damaging lengthening forces. Interestingly, stretching does not seem to positively influence length-tension relationships in the same fashion as eccentric training, which improves the ability of a muscle to produce force in a lengthened position (Proske & Morgan et al., 2001). Accordingly, this lead O’Sullivan et al. (2012) to question if eccentric training, which has proven benefits in injury risk reduction and power development, could be utilised to improve flexibility (Askling et al., 2003; Mjølsnes et al., 2004).
Eccentric Training and Sarcomerogenesis?
Animal model studies have shown the addition of sarcomeres in series (termed sarcomerogenesis) in response to eccentric training (Lynn & Morgan, 1994). For those of you who need a little brush up on your muscle biology and anatomy, check out the short video below. Essentially, muscles are made up of sarcomeres aligned in series which contract and expand to shorten and lengthen a muscle. Sarcomerogenesis, or the addition or sarcomeres, could theoretically make a muscle longer and increase muscle fascicle length. Therefore, it has been suggested that such sarcomerogenesis may improve the flexibility of the targeted muscle.
O’Sullivan et al. (2012) performed a systematic review to determine the effects of eccentric training on lower limb flexibility.
So, What Did They Find?
The study included 6 high quality studies evaluating the impact of eccentric training on various lower limb muscles. These were:
- 2 on Quadriceps (Blazevich et al., 2007; Reeves et al., 2009)
- 2 on Hamstrings (Nelson & Bandy, 2004; Potier et al., 2009)
- 2 on Gastrocsoleus (Duclay et al., 2009; Mahieu et al., 2008)
Each of the studies evaluated outcomes of either;
- Range of motion (ROM): assessed via various clinically applicable techniques
- Muscle Fascicle Length (LF): as evaluated by ultrasound
Interestingly, all 6 studies consistently showed increases in ROM or FL following a program of eccentric training. If you want to talk figures, the improvements include:
- Hamstrings: increases in ROM 6.9 – 12.79 degrees and FL of 34%
- Gastrocsoleus: increases in DF ROM of about 6 degrees and FL of 1.01mm
- Quadriceps: increases in FL of 3.1 – 22%
Clinical Implications of This Research
The obvious clinical implications of this research is that all studies showed clinically relevant improvements in ROM and FL. Whilst this may not necessarily be related to muscle length, particularly in bi-articular muscles, it does show promising clinical results! It is also worth noting some programs were as short as 6 weeks and displayed significant improvements in flexibility (O’Sullivan et al., 2012). However, before you go give all and sundry eccentric exercises, the research does pose some questions…
Some Questions Worth Answering
The questions that still need to be answered include the impact of:
- Injured vs uninjured athletes (these studies featured uninjured subjects)
- Dosage changes – weight, prescription, frequency, etc
- Varying chosen exercises
- Adding other rehabilitation techniques e.g. stretching and eccentric exercises
What Are Your Thoughts?
Can eccentric exercise replace stretching as the most appropriate exercise for improving flexibility in injury rehabilitation? What is your experience using eccentric exercise to improve range of motion; good, bad or negligible? Be sure to let me know in the comments or catch me on Facebook or Twitter.
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Photo Credit: BruceW.
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Mahieu NN, McNair P, Cools A, et al. Effect of eccentric training on the plantar ﬂ exor muscle-tendon tissue properties. Med Sci Sports Exerc 2008;40:117–23.
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Murphy DF, Connolly DA, Beynnon BD. Risk factors for lower extremity injury: a review of the literature. Br J Sports Med 2003;37:13–29.
Nelson RT, Bandy WD. Eccentric training and static stretching improve hamstring ﬂexibility of high school males. J Athl Train 2004;39:254–8.
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Iulia dragoi says
I am happy with excentric ex regarding to muscle lenght improvement,unfortunateli,i think it is not enough,i always check muscle stiffness and try to balance with motor control ex ,as for ex when having a short hamstring,i will always try to stretch it while increasing at the same time the back extensors.
In athlets with no injuries,excentric ex realy work
very true…eccentrics training will improve flexibility but , its effects take around minimum 6 weeks right…….so it can be given as a long term measure or in off season training to atheletes…….. but if there is as athelete with injury due to reduced lower limb flexibility…….. eccentric training is only added in the 2 nd phase of rehab (that is once the initial inflammation and pain reduces……doesnt seem practically applicable or new stuff…….
Jesse Schulz says
I have done a similar review about a year ago at the prompting of a high school soccer coach after a discussion about the benefits of stretching. I started utilizing a lot more eccentric stretching in my clinical practice after my review and found pretty amazing results across the board compared to other types of stretching. In 5-6 repetitions of gentle eccentric stretching I can usually get a 10 degree or greater increase in ROM. When you consider that this takes place in 30-35 seconds it is pretty impressive. I would like to see a study done in the future with comparing eccentric stretching for a total of 90 seconds compared to positional release/strain-counterstrain for the same time period. I think that there is some neuromuscular factor, currently undescribed in the literature that I have seen, that is responsible for the individuals that do static or dynamic stretching, but get little to no improvements. These are the individuals in my mind, that bring up the question of “is stretching worthwhile?” Likely a different approach to static or dynamic stretching is needed, hence the effectiveness of eccentric stretching.
Cheers and happy stretching…if you choose to!
Jesse Schulz, PT, DPT