Sprinting and positions of power


In May, I referenced the picture above in an article about the media and duck feet. At the time, I received an email that referred to girls basketball and ACL injuries. Essentially, the email said that the coach saw a lot of girls running with their feet out (external rotation) and their knees caving in (valgus), which would seem to put the player at risk for an ACL injury.

2013 Big State Flava JamYesterday, while reading about some of the summer girls basketball tournaments, I saw the picture to the right. Notice a difference between the girl in the photo and the 100m runners above, especially the runner in blue?

It’s hard to make 100% accurate evaluations of movement because the picture to the right is not taken straight on, but at an angle, so it could be deceiving. However, at foot contact, it appears that her left foot points slightly to the left (good), but her knee tracks slightly toward her midline (bad). This would appear to match the description that the coach had emailed me about in May.

Is this a problem? Is the problem the externally rotated foot, as the baseball writer seemed to believe? Is the problem the knee valgus?

Assuming the athlete moves as it appears in this picture, and the picture is not deceiving, the issue is the knee valgus, not the external rotation. To develop strength and power, a slight external rotation is recommended, though the recommended angle is generally less than 15-degrees. The knee valgus, however, has been identified as a precursor to an ACL injury. The problem is likely not the foot or knee, but elsewhere.

The problem is likely one of poor motor control or an issue with the hip (mobility or strength) or ankle (mobility). Because the player has likely been a top athlete for most of her life (I don’t know her name, but it seemed that she was ranked nationally in her class), I imagine that nobody has seen a flaw in her movement. After all, a great player must be a great athlete, and a great athlete would never have a movement issue; it’s like some transitive property.

Therefore, this could be a learned technique due to a lack of awareness of a more optimal movement pattern, which would require some focused re-learning to change the movement pattern to a more optimal stride.

Alternatively, the poor motor pattern could be caused by a lack of strength or mobility. In one of his reviews, Chris Beardsley reviewed a study by Padua, Bell and Clark (2012). This study used an overhead squat and compared a control group to a knee-valgus group. “The researchers concluded that the EMG activity levels of the gastrocnemius, tibialis anterior and adductors were greater in subjects who displayed knee valgus than those who did not” (Beardsley). The researchers suggested that the activity of the gastrocnemius and tibialis anterior could indicate that dorsiflexion stiffness caused the knee valgus in the overhead squat. If the same was true in a stride or sprint, this player would need mobility work for her ankle. Also, if true, it would not surprise me if she had sprained an ankle and not fully rehabilitated the ankle after the sprain, causing reduced dorsiflexion.

In an article by Bret Contreras, he identified the overactive adductors mentioned in the study by Padua et al. (2012) in conjunction with weak gluteals. The Padua et al. (2012) study, however, found no differences in gluteal strength between the two groups, though that is a widely-held belief. Contreras also identified the lack of dorsiflexion, and added weak VMO (vastus medialis obliquus) and hamstrings.

In the past, I have used mini-band walks to combat knee valgus due to poor glute medius strength. However, after hearing Charlie Weingroff denigrate band walks and suggest that using a tonic  muscle (resist movement) as a phasic muscle (move the body) is a CNS stressor, I am reevaluating my use of band walks. I have found that single-leg hops improve motor control and hip stabilization, which has reduces knee valgus. Variations include: stationary, repeat stationary, side to side, horizontal hop for distance, and repeat horizontal hops.

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