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Resistance Training/Periodization

(14) HEEL HEIGHT DOES NOT ALTER CONCENTRIC OR ECCENTRIC BARBELL VELOCITY

Thursday, July 11, 2024
2:00 PM – 3:30 PM East Coast USA Time
Location: Exhibit Hall
Abstract Details:

Background: While footwear design and components vary greatly based on their intended purpose, a common design feature of contemporary athletic footwear is a heel-to-toe height differential (e.g., elevated heel height). Prior research has indicated that moderate heel height differentials can lead to altered lower extremity joint kinetics, muscle activity, and reduced lifting capacity. There have also been indications that even a small heel height differential leads towards less hip flexion during the squat, with an individual displaying a more upright posture, during the execution of a squat; however, minimal information is available on the impact of elevated heel heights on the influence of barbell velocity during the lift, a common method of intensity prescription for many strength lifts.

Purpose: The purpose of the present study was to examine the influence of elevated heel heights on concentric and eccentric barbell velocity during a back squat at 75% of a participants 1RM.

Methods: Twenty (age = 22.3±4.1 years) resistance trained participants (males, n = 10; females, n = 10) took part in a randomized protocol of three repetitions at 75% of their maximal effort barbell squat (1RM) at a 0, 5, 10, or 15 degree incline. Participants performed three successive repetitions per condition, with zero inter-repetition rest, and 5 minutes of rest between conditions. Participants were instructed to complete a full squat; however, participants were not provided external feedback as to the squat depth. Heel height was adjusted to the designated heel height through custom-made wooden-lifting platforms set to specific incline levels (0%, 5%, 10%, and 15%) while all participants utilized a standard, zero-drop (e.g. flat) athletic shoe. This led to a relative heel height differential based on the foot size of the individual, based on prototypical footwear design specifications. Sagittal plane kinematics were collected through a single Basler Scout camera recording at 100 Hz and processed through MaxTRAQ2D. A custom Matlab program was utilized to determine the average barbell velocity during the eccentric and concentric portion of each repetition, with velocities averaged across the three repetitions. Separate repeated measures ANOVA’s were completed to examine the influence of heel height (0, 5, 10, 15%) on barbell velocity during each phase.

Results: While descriptive statistics indicated that barbell velocity tended to slow during the concentric portion of the movement as heel height increased, statistical analyses indicated no significant differences in either concentric or eccentric barbell velocity as heel height was increased.

Conclusion: There has been much discussion about how the footwear utilized by athletes may affect their ability to perform during a strength training session. While the present study only looked at barbell velocity during a squat, results indicate that altering heel height would not alter barbell velocity. PRACTICAL APPLICATION: The present study suggests that heel-to-height differentials, a common component of most athletic footwear, will not have alter barbell velocities during a barbell squat. As such, Strength & Conditioning Coaches that utilize velocity-based exercise prescription may not need to adjust training zones based on varying footwear utilized by athletes during training sessions.

Acknowledgements: None