No Changes in Lower-Body Muscle Size and Force Characteristics Following Short-term Autoregulatory Progressive Resistance Exercise

Authors

Andrew J. West, Tarleton State UniversityFollow
Sierra M. Washington, Tarleton State UniversityFollow
Annalee G. Krahn, Tarleton State UniversityFollow
Dylan J. Harty, Tarleton State UniversityFollow
Jenaya V. Brown, Tarleton State UniversityFollow
Mason A. Crews, Tarleton State UniversityFollow
Andru N. Botello, Tarleton State UniversityFollow
Sarah N. Fambro, Tarleton State UniversityFollow
Adriana Alonso Gomez, Tarleton State UniversityFollow
Andrew A. Wolfe, Tarleton State UniversityFollow
Micheal J. Luera, Tarleton State UniversityFollow

Abstract

Autoregulatory progressive resistance exercise (APRE) programs dynamically adjust training intensity based on individual performance. The use of an APRE training program may provide further insight into the mechanisms that contribute to acceleration in strength gains and muscular hypertrophy. These mechanisms can be examined through the change in rate of force development (RFD) and cross-sectional area (CSA) following a mid-thigh pull. PURPOSE: The purpose of this study was to examine changes in muscle morphology, peak force, and RFD in the VL following a 4-week APRE training program. METHODS: Eight resistance trained males (age: 21.5 ± 2.3yrs; height: 176.5 ± 6.8cm; weight: 70.3 ± 17.8kg) participated in a 4-week APRE training program. Resistance trained males were taken to absolute fatigue for 2 sets using approximately 85% of 1RM for compound lifts such as the squat, bench, deadlift, and overhead press. Pre and post measures were recorded during an isometric mid-thigh pull to compare RFD during the early phase of force production (0-50ms, 50-100ms, and 100-150ms) and peak force. Ultrasound images were also taken to compare the changes in CSA in the VL following the training study. Paired samples t-test were used to compare the pre and post measurements for CSA and peak force. Furthermore, a mixed factorial analysis of variance (time [pre v post] x RFD [0-50ms v 50-100ms v 100-150ms]) was used to compare RFD in 50ms epochs during the early phase of the mid-thigh pull. RESULTS: There was not a significant difference in CSA from pre to post (p = 0.81; 27.39 ± 2.60 to 27.12 ± 1.91; mean ± SE). Additionally, there were no significant differences in peak force from pre to post (p = 0.58; 1860.76 ± 206.04 to 1908.71 ± 185.84; mean ± SE). Lastly, there were no significant time x RFD interactions (p = 0.735) or main effects for time (p = 0.956) or RFD (p = 0.077) between the early phase 50ms epochs. CONCLUSION: The program did not yield significant changes in muscle morphology, peak force, or early-phase RFD, likely due to the participants' training style and brevity of training duration. For resistance training participants, future research should consider an intervention lasting ~8-12 weeks to better capture potential improvements in muscular performance.

Recommended Citation

West, Andrew J.; Washington, Sierra M.; Krahn, Annalee G.; Harty, Dylan J.; Brown, Jenaya V.; Crews, Mason A.; Botello, Andru N.; Fambro, Sarah N.; Alonso Gomez, Adriana; Wolfe, Andrew A.; and Luera, Micheal J. (2025) "No Changes in Lower-Body Muscle Size and Force Characteristics Following Short-term Autoregulatory Progressive Resistance Exercise," International Journal of Exercise Science: Conference Proceedings: Vol. 2: Iss. 17, Article 60.
Available at: https://digitalcommons.wku.edu/ijesab/vol2/iss17/60