This a review of a the following paper.
Willy and Davis, 2011. The Effect of a Hip –Strengthening Program on Mechanics During Running and During a Single-Leg Squat
Journal of Orthopaedic and Sports Physical Therapy / Vol 41 / Number 9 / September / Pg 625-632
This study was carried out to look at the effects of a hip-strengthening program combined with movement training of a single leg squat during running and squatting in females who exhibited abnormal mechanics during running despite being pain free. The abnormal mechanics, which were studied, are often associated with conditions such as tibial stress fracture, iliotibial band syndrome and patellofemoral syndrome. Physiotherapy for these conditions and altered biomechanics typically includes hip strengthening, which has been shown to improve symptoms but it is unknown if the underlying mechanics during functional movements are altered.
STUDY STRENGTHS
Based on the power calculation carried out prior to commencing the study, 9 runners were required to adequately power the study as such each group had 10 runners per group. The participants were blinded to the kinematic qualification. The strengthening program that the study used was one that is commonly used by physiotherapists. The exercises chosen have been shown to invoke high activity from the hip abductors and external rotators. It was a 6-week program requiring the subject to exercise 3 times per week, twice unsupervised and once supervised by a physiotherapist. All movement training carried out was specific to the single leg squat.
STUDY WEAKNESSES
While motion retraining was carried out, it was only based on retraining of the single leg squat rather than involving any movement training while running. While strength gains were noted the extent of this may be unrealistic as the subjects had abstained from lower extremity strength training for 90 days prior to commencing the study. A further limitation of this study is that only pain free individuals were tested and thus care must be taken when generalizing these results to the symptomatic population.
COMMENTARY OF RESULTS
Results of this study concluded that:
- Hip strengthening combined with movement training of the single leg squat has a positive effect on the mechanics of a single leg squatting.
- Hip strengthening alone does not have any effect on the biomechanics of running on hip and knee kinematics.
REAL WORLD IMPLICATIONS
A component of neuromuscular training combined with strength training seems to be the most advantageous way to influence running style and mechanics. Strengthening alone does not seem to be sufficient to alter running mechanics. As there was movement training of the single leg squat in this study it is not possible to advise whether hip muscle strengthening alone would have an influence on the mechanics of a squat. From a physiotherapy point of view it is difficult to comment on the implications of this study in practice as clients predominantly present to physiotherapy complaining of pain but the population studied in this were all asymptomatic and pain free. However, it is possible to suggest that a 6 week hip strengthening program does have a positive effect on hip strength. While this is an important factor, in order to influence functional activity, such as running it seems that some elements of neuromuscular/movement training should be included in rehabilitation programs provided by therapists in order to ensure that the biomechanics of the functional activity are also altered.
MORE INFORMATION REQUIRED
Further studies are required to assess the effect of neuromuscular training alone combined with neuromuscular training combined with strength training on running in the asymptomatic population. These studies would then need to be progressed to look at a symptomatic population.
IMPLICATION
In order to affect abnormal running mechanics, therapists should incorporate neuromuscular training into rehabilitation programs, rather than focusing on muscle strengthening alone. Rehabilitation programs need to incorporate these two components in order to be successful based on the findings of this study.
Thanks for reading.
Suzanne Donnelly
MSc (Adv Neuromusculoskeletal Physiotherapy)
Senior Physiotherapist