runner glutes

Runner-Specific Gluteal Activation – The Crossed Extensor Reflex

When it comes to runners injuries the gluteal muscles have become a prime target for rehabilitation and strengthening.  The research repeatedly implicates weak, delayed and reduced activation time of gluteal muscles as a key component in a multitude of running related injuries (RRI’s). Whether gluteal dysfunction is a cause or result of RRI is open to debate with some now challenging the common belief that gluteal dysfunction precedes injury. For now, the current paradigm is that gluteal dysfunction is a pre-cursor to RRI and as such should be addressed in rehabilitation. Time will tell if this paradigm holds up to ever more rigorous research as both technology and research methods improve.

With improvements in EMG recording, 3D kinematics, force plates, accelerometers and computer modelling over the last 10 years our knowledge of the exact function of muscles continues to grow. The exact functional capabilities of the Gluteus Medius, Minimus and Tensor Fascia Lata however are still poorly understood with undoubtedly crossover of function occurring [1].  As our knowledge grows this should help to define our treatment options more clearly.  These muscles are commonly referred to as the hip abductors but might be better functionally termed the lateral pelvic stabilisers as this role is far more common. We don’t after all walk or run around throwing our legs out to the side that often. We also think the hip abductors are involved in lower limb stability and with poor activity we might see a dropping hip or knocked knee effect –see below. The gluteus maximus likewise is most often thought of as a hip extensor but is probably far more involved in controlling trunk flexion to stop us falling forward. Certainly in running it is involved in decelerating the swing leg and initiating hip extension but the hamstrings also play a major part in this. With poor gluteus maximus function we might see increased forward lean and arched lower back (hyperlordosis).  

 

                                                          

  Poor  Lumbar stability (inactive glute max)                                       Pelvic instability (lumbo-pelvic area affected)                       Lower limb Instability (knee and ankle affected)     www.faithbebbington.co.uk

 

 Due to the current paradigm that weak gluteal muscles precede injury so gluteal strengthening exercises are incorporated into our own rehabilitation programs. In our Runners Edge Performance Program at the Sports Surgery Clinic several of these exercises are used.

http://www.youtube.com/watch?v=GLd6Rm3pdXw

http://www.youtube.com/watch?v=hViSdvv6Huw&list=PL0fkghT-Zc671NmgmQEHVC0o2YFh9ixSZ

http://www.youtube.com/watch?v=59_t0kVwu9o

Reiman et al. 2012 [2]produced some great graphs to indicate which exercises produce the highest activation of the gluteal muscles. These can serve as a useful guide to exercise prescription.

 

 

 

 

Reiman et al. 2012

Some demonstrations of some of these can be seen on the excellent blog of running physio Tom Goon on:

 http://www.running-physio.com/tag/gluteus-maximus/         or

http://www.running-physio.com/tag/gluteus-medius/

  You’ll notice that the exercises are measured as a % of maximal voluntary isometric contraction with the best exercises reaching around 75%. Interestingly we can achieve better than this in an even more functional manner. Kyröläinen et al. 2005 [3]showed that when running at high speeds  gluteus maximus activity  was higher than we can voluntarily maximally contract the muscle. It stands to reason therefore  that short sprints and shuttles could be another great way of functionally activating  the gluteals if the athlete is able to perform these. This is good news for runners not keen on the gym. Likewise Rand and Ohtsuki, 2000 [4] showed quick changes of direction could also activate the gluteus medius more than a voluntary maximal contraction.  Adding some off road, sand dune, fast multi directional cone work or ball games may therefore do wonders for some functional gluteus medius activation. We don’t have to limit ourselves to the gym for strengthening these muscles.

What else can we do to improve functional running activation of the gluteal muscles? First of all we need to know when the gluteal muscles are actually firing. Have a look at the pics below and try to decide when the glutes are firing .You may be surprised to know that the leading leg of the runners on the left demonstrates the initial gluteal activation point and there is very little activation in the  hind leg of the ladies on the right.

Image from www.runningskirts.com

In normal running the gluteal muscles start firing in the late swing phase prior to the foot hitting the ground. This activity builds up to accelerate the thigh down and backwards, to push the pelvis forwards and to stop the torso falling forward. The glutes reach a peak of activity in the early stance phase then remain quiet in the last half of ground contact [5]. Most of the work is done in the pre- and early contact phase and contrary to popular belief they do not function to push backwards in the last part of the stance phase.

 

 

 

Gluteus maximus activity during stance phase of running.Sasaki and Neptune, 2005

 

 Luckily we don’t have to think too much about sequentially activating all of our muscles to run.  Although the intention to run is initiated in the brain, muscle activation is controlled by reflex activity which is then fine-tuned by both the brain and sensory feedback .  Without going into too much detail the gluteal muscles are switched on as a reflex reaction to lifting the opposite foot from the ground. This is called the Crossed Extensor Reflex (CER) and occurs either automatically as a response to stepping on something painful such as a tack (see below) or triggered by hip flexion of the opposite leg at the toe off phase. By flexing the hip soon after ground contact the resultant activation of the CER causes gluteal activation in the opposite leg to initiate the downward/backward drive of the thigh. In parallel we also see knee extensor activation in preparation for weight-bearing. Thus it is the early activation of this reflex that we strive for when attempting to improve gluteal activation when running. A rapid hip flexion of one leg corresponds to rapid hip extension of the opposite leg in a scissor like action.  After watching slow motion video of over a thousand runners I can confidently say this scissor like action occurs synchronously at the moment the hind knee starts driving forward. The front knee is at its highest point when this occurs and also starts to extend in preparation for weight-bearing. The activation of the gluteal muscles is therefore directly linked to the activation of the contralateral hip flexors.

 

 

 

 

 After trialling several different coaching cues to activate this reflex I discovered a great technique used by a research colleague at the Sports Surgery Clinic. Brendan is a National level long jumper and suggested a cue he uses in training. This involves visualisation of a glass window immediately behind his feet when running.  He then has to avoid putting his feet through the glass by rapidly lifting his foot straight up towards the buttock soon after foot-strike. This is infinitely better than running on tacks and achieves several other benefits. These include short ground contact time, reduced hip extension, higher step rate, faster hip flexion and resultant earlier activation of the crossed extensor reflex. This has gone on to become one of the key coaching cues I use in the clinic. For those familiar with Frans Bosch’s work this helps to achieve a positive running style. For Pose Runners this is akin to the foot lift under the hips. 

 

 

 

 We use this cue not to achieve a certain pose or improve speed but to improve activation of more proximal muscles. This fits with our underload/overload theory in which we believe that overload in distal limb segments can be transferred to more proximal areas by alteration of running technique. Our athletes certainly tell us they feel their hip flexors and gluteals working harder so our next step is to investigate this with EMG.

 Most of the action of running happens at a subconscious level based on intention to move and a series of reflexes modified by feedback. We can modify the reflex behaviour of the muscles involved with a few coaching cues and give feedback to whether the correct movement pattern is achieved.  After initial feedback the athlete must then learn through repetition how it ‘feels’ when performing the desired running technique.  Our subjects tell us that although strange at first, they find that new technique starts to feel normal within 3-6 weeks of practice. Greater fatigue is normal as muscles not used to working will initially be used. This seems to be a transitory phase. At the 6-8 week point many of our elite runners then report they are running at their normal pace but have more in the tank. A national age group sprinter recently returned to thank us for not only solving his recurring metatarsal stress reaction but helping him to win the Nationals by 0.01 secs. If you have been told to work the glutes more think about the glass pane and lift the foot to the butt to stimulate your crossed extensor reflex, add some speed work and get off-road to get some real runner-specific gluteal activation.

Stay inFORMed

1.            Flack NA, Nicholson HD, Woodley SJ: A review of the anatomy of the hip abductor muscles, gluteus medius, gluteus minimus, and tensor fascia lata. Clinical anatomy 2012, 25(6):697-708.

2.            Reiman MP, Bolgla LA, Loudon JK: A literature review of studies evaluating gluteus maximus and gluteus medius activation during rehabilitation exercises. Physiotherapy theory and practice 2012, 28(4):257-268.

3.            Kyrolainen H, Avela J, Komi PV: Changes in muscle activity with increasing running speed. Journal of sports sciences 2005, 23(10):1101-1109.

4.            Rand MK, Ohtsuki T: EMG analysis of lower limb muscles in humans during quick change in running directions. Gait & posture 2000, 12(2):169-183.

5.            Sasaki K, Neptune RR: Differences in muscle function during walking and running at the same speed. Journal of biomechanics 2006, 39(11):2005-2013.

6.            Bosch F, Klomp R: Running: Biomechanics and Exercise Physiology in Practice

 

 


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