Part of being a physiotherapist, who is involved with athletes, is finding solutions to, at times, difficult problems. So, when I read a study, which provides not only interesting findings, but helps me assist my patients to achieve their absolute best during rehab, quite frankly, I’m stoked. That’s the exact feeling I had when reading the Lenhart et al (2014) paper on hip muscle activation during running at different speeds. These researchers wanted to examine the difference in activation of muscles, surrounding the hip, at different stepping rate paces including, 90%, 100% and 110% of their regular pace. Increasing running step rate (cadence) has previous been advocated as a method of decreasing the load transmitted through the hip, therefore allowing better recovery and rehab, whilst still maintaining running. If you’ve had a running injury or have been experiencing discomfort whilst running, pay close attention as some of these findings may help you get back on the track sooner and for longer! At the normal pace (100%) the muscle which worked the hardest on ground contact was the gluteus medius – A very important muscle for hip stability, as it resists the hip dropping on ground contact and keeps the trunk upright. In fact, the sum of the forces of the gluteus medius and minimus was 3.5 times that of the gluteus maximus. Something to consider for all runners! During the early and late swing phase, the iliacus and semimembranosis were most active, respectively. The most interesting and rehab relevant findings were when the researchers examined running at higher stepping rates.
At ground contact, the load through the gluteals, rectus femoris (quadricep/hip flexor), adductor magnus (groin/small ‘hamstring’ role) and piriformis (deep hip external rotator) all decreased. However, this increase in step rate also resulted in higher hamstring muscle load. As the limb was off the ground (swing phase) the load through tensor fascia latae (hip flexor, important muscle for ITB issues), gluteus minimus, rectus femoris, adductor brevis (groin) and the hamstrings and glutes (especially later in swing), all increased.
The changes in gluteal muscle activation (-10%) appear to be proportional to the increase in step rate (+10%). This is likely due to the glutes role in maintaining vertical alignment, of the body, as well as braking, which is reduced as step rate increases. The increased activation of iliacus, rectus femoris, sartorius, tensor fascia latae, gluteaus minimus and adductor brevis is due to each having either a primary or secondary role as a hip flexor. The recommendations from Lenhart et al (2014) are as follows;
Training should mimic the negative to positive work occurring during the stretch-shortening cycle whilst running. Perform eccentric contractions immediately followed by concentric contractions.
Examples of exercises include; A skips (hip flexors), B skips (hip flexors & hamstrings), split squat jumps (gluteals). These can be re/progressed as required for each patient.
High repetition training is favourable due to low load/high repetitions during running
Ensure you train all gluteus muscles, especially gluteus medius. It produces the greatest force of gluteal muscles during running and one of most common muscles to develop musculotendon issues, such as tendinopathy!
The authors did also declare some limitations in this study. A few muscles were left out of the study and some others were simplified; the percentages of step rate were self-selected initially by participants (ranging from 2.4-3.8m/s) therefore may not be completely applicable to faster or slower speeds; all participants were healthy and thus application to injured people may yield different results. All of these are fair points, however I think the information presented creates a base for an experienced health or fitness professional to apply to their patients.
Here are your take home points;
1. Train ALL of your glutes
2. Train appropriately for return to running
3. Increased step rate = hip flexor, hamstring and gluteal activation increases in swing and decreases in ground contact So don’t quit running just because you’ve been having pain. Catch up with your physio and discuss ways, such as the ones mentioned above, to get you back on the track sooner and in less pain! Lenhart, R., Thelen, D., & Heiderscheit, B. (2014). Hip Muscle Loads During Running at Various Step Rates. Journal of Orthopaedic & Sports Physical Therapy, 44(10), 766-A4.