Date of Award

8-2025

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Kinesiology and Nutrition

Committee Chair

Trenton Gould

Committee Chair School

Kinesiology and Nutrition

Committee Member 2

Paul Donahue

Committee Member 2 School

Kinesiology and Nutrition

Committee Member 3

Tanner Thorsen

Committee Member 3 School

Kinesiology and Nutrition

Abstract

This study examined sagittal and frontal plane kinematics and kinetics during countermovement jump (CMJ) landings performed with either a traditional barbell (BB) or a hexagonal bar (HEX) across increasing submaximal loads in recreationally active males. Generally, hip and knee flexion angles and joint mean angular velocities decreased as loads increased. Hip extension and knee flexion moments increased as load increased up to 20 kg, at which point these values decreased. Performing the CMJ with the HEX exhibited increased frontal plane stability compared with the BB group. Additionally, the BB group exhibited stiffer landing strategies, with decreased sagittal plane joint angles and slower joint angular velocities than the HEX group. Despite hypothesizing that increasing external load would increase landing forces, vertical ground reaction forces were not affected by either training modality or load. These results suggest that regardless of bar type, participants employed joint-level neuromuscular landing strategies that mitigated the increased forces as load increased. Joint moment analysis revealed that the BB group exhibited greater knee extension moments, while the HEX group had increased hip extension and ankle plantarflexion moments. These findings indicate that performing the CMJ with the HEX results in improved energy dissipation techniques by directing the increased forces to the large muscle groups surrounding the hip. Additionally, the BB group relied upon the ankle and knee joints for energy dissipation during landing, while the HEX group utilized a more “hip-dominant” strategy. The BB group also displayed stiffer landing kinematics and kinetics that may increase injury risk at loads greater than 20 kg. This research underscores the importance of load modality selection in plyometric training, with a focus on both performance optimization and injury prevention. Athletes and coaches should consider these results when utilizing plyometric training with external loads, as performing a CMJ with a HEX may encourage landing strategies that improve athletic performance without increasing undue injury risk due to improper landing mechanics.

ORCID ID

0009-0005-2111-6840

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