Seasonal Changes In Dorsiflexion And The Relationship To Training Load Metrics In American Professional Soccer

BACKGROUND: Dorsiflexion range of motion (DFROM) is of concern in soccer athletes due to the movement profile and ball control that requires eccentric and concentric actions at the talocrural joint. A season's demands can lead to overuse, contributing to reduced DFROM, and limb asymmetries. GPS technology quantifies training load, but specific metrics that influence overuse are unclear. The purpose of this study was to investigate how DFROM changes over a season and its relationship with different training load metrics. METHODS: 15 male United Soccer League players were tested for DFROM at preseason, midseason, and postseason. The Weight Bearing Lunge Test assessed bilateral DFROM. Wearable sensors tracked total distance covered in km, number of sprints exceeding 5.5 m/s, and number of accelerations and decelerations from 3 to 10 m/s at each session and match. Variables were averaged weekly for each player. Preseason involved training sessions and non-point matches; midseason covered matches 1-25; late season included the final seven and a half weeks. Changes in DFROM were analyzed using separate one-way repeated measures ANOVA. Pearson’s product moment correlations examined relationships between variables, with significance set a priori at p ≤ 0.05 for DFROM change and p < 0.01 for correlations. RESULTS: No significant main effects were found for dominant limb DFROM (8.9 ± 2.75 cm vs. 8.21 ± 5.57 cm vs. 8.11 ± 2.89, p = 0.065), non-dominant limb DFROM (9.33 ± 2.31 cm vs. 8.87 ± 2.84 cm vs. 8.77 ± 2.65 cm , p = 0.346), or DFROM limb asymmetry (0.83 ± 0.88 cm vs. 1.68 ± 1.28 cm vs. 1.34 ± 1.07 cm, p = 0.053). No significant relationships between DFROM change scores and GPS metrics were observed (p > 0.01). CONCLUSIONS: Although statistical significance was not met, clinically significant changes to DFROM were observed. Average DFROM decreased throughout the season, and asymmetries increased by 33% from pre to midseason, with a 6% decrease by postseason. This suggests it may be beneficial to monitor DFROM throughout the season to manage injury risk. Additionally, 80-86% of participants failed to reach normative values throughout the study. Given the lack of relationship observed, total distance, number of sprints, accelerations and decelerations may not influence DFROM in professional soccer players.