Athos Science: Recruitment Patterns Changing

By Daniel Feeney

Athos Insights

Using Athos to track recruitment patterns to better understand the way your athletes bodies work during training can help coaches make better, more informed decisions.

Changes in activation patterns can be tracked and monitored to avoid injury. For example increased reliance on the hamstrings for hip extension instead of the glutes is something we found with one of our athletes that was flagworthy.

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These insights allow coaches to establish normative contributions for athletes for movements they perform frequently and see how these patterns change due to fatigue or other factors. This also helps them to tailor the training of the athlete to strengthen specific muscles and increase the control of movements. All of this is important as it leads to improved quality of movement and likely reduced injury risk.

Learn more about these insights below.

What we did

Coaches often ask athletes to perform intervals based on an external measure of load. For example, a track coach may ask their athletes to run 12 x 400m repeats in a given time.

The time may be based off a percent of their VO2 max, lactate threshold, or race performance, but there are infinitely ways to accomplish this task within the subspace of muscle activation patterns, however some are movement patterns are less prone to injury than others.

Athletes performed 6-8 x 400m repeats starting at a rate of perceived exertion (RPE) of 8/10. After the first interval, athletes were asked to keep their 400m time within two seconds of the first interval. This goal was accomplished by all athletes for seven repeats, on average.

We tracked how muscular activation patterns differed on each interval. All athletes reported increasing effort to maintain the same speed as the intervals went on.

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Figure 1. Gluteus maximus, biceps femoris, quadricep percent contribution for each of the seven intervals that all athletes performed.

A fascinating trend was observed for each athlete individually and group wise. Early intervals had a significantly greater percentage contribution from gluteus maximus, which was significantly lower by the end. In contrast, biceps femoris (hamstring) contribution increased to compensate for the decline in gluteus maximus activation.

What this means

These insights allow coaches to 1) establish normative contributions for athletes for movements they perform frequently (running intervals, doing a 5-10-5 drill, scrimmaging) and 2) see how these patterns change due to fatigue or other factors, and 3) tailor the training of the athlete to strengthen specific muscles and increase the control of movements (i.e. activating gluteus maximus even under fatigue). This leads to improved quality of movement and likely reduced injury risk.

A sudden and sustained increase in hamstring contribution could lead to injury. The Biceps femoris crosses both the hip and knee joints. As such, when the biceps femoris increases contribution during hip flexion instead of gluteus maximus, it is often performing two actions concurrently (hip extension and knee flexion).

The double-action on the hip and knee joints from biceps femoris can lead to greater loads placed on the tendons and connective tissue (Lewis et al., 2007), and could be related to injury risk (Sahrmann, 2002) for patellofemoral pain and increased pelvic instability (Wilson et al., 2005).

To fix a movement pattern that gradually reduces gluteus maximus and increases biceps femoris contribution, a coach could program increased strength training and specific coordination movements that target gluteus maximus activation. This may alter motor patterns during later intervals and lead to more consistent activation patterns.

Using this framework, a coach can be proactive instead of reactive in preventing injury risk and prescribing training volume. If an athlete is compensating by creating movement with their hamstrings instead of glutes, it may be beneficial for the coach to stop the session early or use activation exercises (Parr et al., 2017) to increase glute activation.

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References

Lewis CL, Sahrmann SA, Moran DW. Anterior hip joint force increases with hip extension, decreased gluteal force, or decreased iliopsoas force. Journal of Biomechanics 40: (16):3725-3731, 2007.

Parr M, Price PDB, Cleather DJ. Effect of a gluteal activation warm-up on explosive exercise performance. BJM Open Sport & Exerc Med. 3:e000245, 2017.

Shirley Sahrmann. Diagnosis and treatment of movement impairment syndromes. Mosby, 2002.

Tyler TF, Nicholas SJ, Mullaney MJ, McHugh MP. The role of hip muscle function in the treatment of patellofemoral pain syndrome. Am J Sports Med 34(4):630–636, 2006.

Wilson, J. Ferris, E. Heckler, A. Maitland, L. Taylor, C. A structured review of the role of gluteus maximus in rehabilitation. New Zealand Journal of Physiotherapy 33: 3(95-100), 2005.*

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