Impact of Ankle Injury History and Pre-National Football League Draft Training on Lower Limb Coordination During...

Objective Ankle sprains are one of the most common injuries sustained by American football athletes. Players with a recent history of ankle sprain, even when asymptomatic, may have sensorimotor impairments that affect control of the hip and knee during dynamic activities such as speed running. Among players preparing for the National Football League (NFL) draft, these functional deficits have wide-ranging effects and warrant systematic investigation. This study aimed to determine the influence of a recent history of ankle sprain (≤6 months) and a six-week NFL draft preparation training camp on hip-ankle (HA) and knee-ankle (KA) coordination. Specifically, we examined HA and KA coordination angles and variability using vector coding. We hypothesized that the group with a recent ankle sprain history (RASH) would express less ankle-dominant patterns, and these would improve post-training, and the RASH group would show impaired neuromuscular adaptability as evidenced by lower coordination variability, but this would improve post-training, through increased variability. Materials and methods This study analyzed a sample of 12 athletes with a recent ankle sprain history (RASH) and compared their running mechanics to 12 matched controls with no recent ankle sprain history (non-RASH). Running mechanics during a five-second 23 km/h run were evaluated pre- and post-training using a 10-camera motion capture system. Coordination was quantified into angles using vector coding, and coordination variability was quantified using circular statistics, with variability expressed as the standard deviation derived from the mean resultant length of angular data. Data for both were derived over four subphases of the running gait cycle: first half stance, second half stance, first half swing, and second half swing. A 2 (RASH and non-RASH) × 2 (pre and post) ANOVA were used to assess the influence of ankle sprain history and training on HA and KA coordination and coordination variability (p ≤ 0.05). Results No significant group × time interactions or main effects were found in any of the subphases for coordination angles or variability for HA and KA (p > 0.05). For HA, there were medium effect sizes in coordination angle for the second half of stance (η²ₚ = 0.075) and coordination variability for the second half of swing (η²ₚ = 0.121). The RASH group had larger increases in HA angle from training (212.7 ± 102.7° (pre) versus 235.5 ± 91.2° (post)) than the non-RASH group (268.7 ± 56.8° (pre) versus 265.5 ± 48.2° (post)). Further, the RASH group shifted from an in-phase hip-dominant to an in-phase ankle-dominant pattern in the second half of stance. For KA, there were medium effect sizes for the first half stance (η²ₚ = 0.093) and second half swing (η²ₚ = 0.091). Specifically, for the first half stance, the RASH group changed from anti-phase ankle to in-phase ankle control (97.0 ± 19.5° (pre) versus 85.5 ± 29.4° (post)), while the non-RASH group was stable at an anti-phase ankle pattern (93.6 ± 19.8° (pre) versus 95.6 ± 19.8° (post)). For the second half swing, both groups produced in-phase knee-dominant patterns, but the RASH group decreased their coordination angle by 4.4°, and the non-RASH group increased their coordination angle by 3.8°. Conclusions Highly skilled athletes with a recent history of ankle sprains adopt compensatory joint coupling strategies that persist even in the absence of symptoms and can be modified through training.