Help me...my "gluts" are not firing...
>> Friday, January 21, 2011
How many times have your heard the following: "your gluts are not firing"? I bet many times. In the World of Strength and Conditioning and Physiotherapy everyone suffers from some form of seasonality/popularity of terminologies, myths and fallacies. We are currently living the era of "the gluts not firing" myth.
Whatever the problem (low back pain, ankle instability, knee pain etc etc.) I bet you that if a physiotherapist or an S&C coach sees you...they will find out your "gluts are not firing".
Few years ago it was all about something to do with your temporomandibular joint, now it is something to do with your gluts, next it will be something about your feet and so on.
I am strongly convinced that the inclination to accept such terminologies and fallacies depends on some courses in which lecturers with dubious qualifications try to "re-invent" the wheel "branding" something esoteric and appealing presenting and packaging it very well. It is a bit like the fad diets. I have to say that this approach clearly works, because the Gluts fallacy (as I will refer to from now on) has clearly gone places as lots of patients/athletes have been "diagnosed" at least once with this problem.
Let's try to discuss this issue using some science.
First of all Anatomy:
The gluteal muscles are the three muscles that make up the buttocks: the gluteus maximus, gluteus medius and gluteus minimus.
The gluteus maximus is the largest of the gluteal muscles and one of the strongest muscles in the human body. It inserts at the iliotibial band and the gluteal tuberosity of the femur. Its action is to extend and outwardly rotate hip, and extend the trunk.
The gluteus medius is located directly under the gluteus maximus. It originates at the back of the ilium below its crest and stretches downward to the greater trochanter of the femur. The gluteus minimus is situated under the gluteus medius; it also originates at the ilium and attaches to the femur. Both these muscles abduct the thigh
For a great interactive online tool, go to the following web address:
http://www.innerbody.com/image/musc08.html
The primary function of the Gluteus Maximus is hip extension (moving the thigh to the rear).
The Gluteus Medius and Minimus serve to abduct (move away from the centerline of the body) the leg
Gluteal muscles EMG activity during running
A very interesting article from Liebermann et al. (2006; J of Exp. Biol.) compared the form and function of the gluteus maximus in Humans, apes and non-human primates. In particular, the researchers were testing the hypothesis that the human gluteus maximus plays a more important role in running than walking. The results of the study showed that "[...] the gluteus maximus is mostly quiescent with low levels of activity during level and uphill walking, but increases substantially in activity and alters its timing with respect to speed during running. The major functions of the gluteus maximus during running are to control flexion of the trunk on the stance-side and to decelerate the swing leg; contractions of the stance-side gluteus maximus may also help to control flexion of the hip and to extend the thigh. Evidence for when the gluteus maximus became enlarged in human evolution is equivocal, but the muscle's minimal functional role during walking supports the hypothesis that enlargement of the gluteus maximus was likely important in the evolution of hominid running capabilities."
When comparing running on treadmill vs running on the ground, Bankoff and Boer (2007; Electrom. Clin. Neurophysiol.) concluded that running on treadmill showed the highest electromyographic (EMG) activity with the gluteus maximus always showing higher activity (root mean square -RMS) than the iliocostalis lumborum muscle.
Rand and Ohtsuki (2000; Gait and Posture) studied lower limbs muscles with EMG during quick change in running directions.
Fig. 4 from Rand and Ohtsuki (2000). Movements and EMG records of all conditions. CON, control straight running condition; STO, visual stimulus condition-open maneuver; STC, visual stimulus condition-cross maneuver; SFO, self-initiated condition-open maneuver; SFC, self-initiated condition-cross maneuver; STF, control stop condition. The subjects changed running direction in response to a stimulus for STO and STC, and changed direction in a self-initiated manner for SFO and SFC. The subjects stopped running in response to a stimulus for STF. The upper part of each plot shows front views from TO of step 3 to the FS of step 5. The lower part shows the examples of raw EMG records of VM, G, GM [Gluteus Medius], and SAR of the right lower extremity (see the text for abbreviations). The arrowhead in the figures (STO, STC, and STF) refers to a presentation of the stimulus. 2FS and 4FS present foot strike of step 2 and foot strike of step 4, respectively.
They concluded that the gluteus medius was mainly involved in modifying foot trajectory of the leading leg during the open maneuver.
EMG analysis of sprinting revealed that gluteus maximus showed similar activities to lateral and medial hamstrings reaching with peak levels of EMG during foot-strike (Jonhagen et al., 1996; Scand J Med Sci Sport). The EMG activity during running is so high that many times reaches average values higher than the ones measured during a maximal voluntary contraction (Kyrolainen et al., 2005; J Sports Sci). In particular when running speed is high.
From this brief analysis of the current literature, it seems clear that the gluteal muscles have an important role in stabilising the hip during running. They are in fact always active during foot strike, and they all contract at once. Most of all, the levels of EMG activity recorded are so high that they can exceed maximal voluntary contraction measured in isometric modality on a dynamometer.
During normal stance and walking the EMG activity of gluteal muscles is relatively small, but it is enough to maintain a stable posture. Just like all the muscles responsible for maintaining the spine stable and the muscles of the lower limbs able to keep you standing.
Without some levels of activation of gluteal muscles nobody is capable of standing still.
So, how about gluts not firing....
Unless the patient/athlete under observation had a spinal cord injury and/or is affected by any neurodegenerative disease, it is physiologically impossible for the gluteal muscles not to be active (or not to "fire"...if you allow me the use of current jargon).
This can be easily tested. in fact a lack of muscle activation in the gluteal muscles during running could be easily identified. If in fact the gluteal muscles are not active during the foot strike, your patient/athlete is going to collapse on the floor.
"Gluts not firing" is therefore an absolute non-sense.
How about abnormal muscle recruitment timing patterns? For example, are the gluteal muscles being recruited at the right time and for an appropriate duration and intensity?
This is a slightly different question. It may be in fact possible that some activity patterns in the affected/injured side might be slightly different in the timing and onset of muscle activation and in the amplitude of the EMG signal. But what defines pathology?
EMG analyses can be conducted to compare for example the "normal" side to the side affected by the injury. However many times the observation "your gluts are not firing" is not matched by electromyographic measurements.
Biomechanical analyses can also be performed to study hip motion, but even here, the "normal" running gait of the patient/athlete should be determined before coming to conclusions just because the hips are moving up and down. Hip motion is in fact affected also by foot placement and knee control. So, an abnormal hip pattern might have nothing to do with activation patterns of gluteal muscles.
In the last two paragraphs I mentioned "abnormal" few times. It is in fact absolutely necessary for everyone (physiotherapists and strength and conditioning coaches) to understand what a normal movement pattern looks like before making a diagnosis.
Conclusions
EMG analysis and biomechanical analyses of running gait should be part of a normal screening pattern for elite athletes in order to have some baseline information of their normal movement patterns. When injuries occur, it is then possible to compare such recordings with injury-free data to be able to identify any anomalies in movement patterns.
Just like every discipline I strongly believe physiotherapy and strength and conditioning should move towards a more "evidence-based" approach.
Before declaring gluteal muscles dead, we should first make sure we know how they "behave" when they are alive!
Author : Dr. Marco Cardinale Read more...
