The Effects of the Repetitive Use of a Position-Specific Loading Pattern on Lower Limb Asymmetry in NFL Offensive Tackles.

Latham, KB. The effects of the repetitive use of a position-specific loading pattern on lower limb asymmetry in NFL offensive tackles. J Strength Cond Res 40(7): 757-768, 2026-American football is a fast-paced, high-impact, collision sport associated with a high frequency of injuries that occur through contact, noncontact, acute impact, or repeated stresses. The purpose of this short-term longitudinal study was to examine developments of musculoskeletal asymmetries through specific loading patterns used by offensive tackles in the National Football League (NFL). Using both cross-sectional and longitudinal designs, strength asymmetry changes in 5 NFL offensive tackles were analyzed pre- and post-training camp, focusing on 3 key isometric strength tests: (a) isometric midthigh pull test, (b) isometric staggered stance pull test (IMSSP), and (c) force frame tests for isometric abduction and adduction strength. A countermovement jump (CMJ) was used to assess dynamic strength. Results revealed statistically significant changes in isometric strength and asymmetry over the course of training camp, with IMSSP ( p < 0.05) and CMJ ( p < 0.05). Notably, post-leg dominance was observed in several athletes in isometric strength. Asymmetry percentages were most noticeable in CMJ tests, with substantial increases in post-training camp asymmetries for several athletes. These findings suggest that repetitive use of a staggered stance position during an NFL training camp can lead to musculoskeletal imbalances in strength between limbs. The results highlight the importance of monitoring isometric strength and asymmetry as part of a tailored strength and conditioning program to mitigate injury risks. Future research should be focused on monitoring strength asymmetry through metrics such as eccentric hamstring strength and for longer. Future training should include alternating positions and incorporating exercises to balance strength across limbs.