A Retrospective Analysis to Determine Whether Training-Induced Changes in Muscle Thickness Mediate Changes in Muscle Strength

Overview

Journal Sports Med

Specialty Orthopedics

Date 2021 Apr 21

PMID 33881748

Citations 1

Authors

Matthew B Jessee

Scott J Dankel

John P Bentley

Jeremy P Loenneke

Affiliations

Soon will be listed here.

Abstract

Objective: To investigate the role of muscle thickness changes on changes in strength following 6 weeks of unaccustomed resistance training, via retrospective analysis.

Methods: 151 participants completed 6 weeks of no intervention (CONTROL), one-repetition maximum training (1RM-TRAIN), or traditional resistance training (TRAD-TRAIN). Groups were assigned by covariate adaptive randomization. 1RM-TRAIN and TRAD-TRAIN performed elbow flexion exercise on the dominant arm 3 times/week. One-repetition maximum strength and muscle thickness (B-mode ultrasound at 50, 60, and 70% of the anterior upper arm) were assessed pre- and post-training. Direct and indirect effects on strength via each training modality were quantified relative to CONTROL using indicator-coded, change-score mediation analyses for each muscle thickness site. Values are presented as regression coefficients (95% CI).

Results: The effect of 1RM-TRAIN on muscle thickness was greater than CONTROL for 60% [0.09 (0.01, 0.17) cm] and 70% [0.09 (0.01,0.18) cm] models. All muscle thickness changes for TRAD-TRAIN were greater than CONTROL: 50% [0.24 (0.16, 0.33) cm], 60% [0.25 (0.17, 0.33) cm], 70% [0.23 (0.14, 0.32) cm]. All direct effects on strength were greater for 1RM-TRAIN versus CONTROL: 50% [1.90 (1.21, 2.58) kg], 60% [1.89 (1.19, 2.58) kg], 70% [1.81 (1.12, 2.51) kg]; and TRAD-TRAIN versus CONTROL: 50% [2.04 (1.29, 2.80) kg], 60% [1.98 (1.22, 2.75) kg], 70% [1.79 (1.05, 2.53) kg]. Compared to CONTROL, there was no indication of an effect of 1RM-TRAIN on strength through muscle thickness (i.e., indirect effect) for 50% [- 0.03 (- 0.17, 0.10)], 60% [- 0.01 (- 0.17, 0.17)], or 70% [0.07 (- 0.09, 0.28)] sites, nor of TRAD-TRAIN for 50% [- 0.11 (- 0.48,0.29)], 60% [- 0.04 (- 0.42, 0.40)], and 70% sites [0.17 (- 0.23,0.58)].

Conclusion: Training-induced changes in muscle thickness do not appear to appreciably mediate training-induced changes in the strength of untrained individuals during the first 6 weeks of training.

Citing Articles

Commentary: Effects of Whole Body Electrostimulation Associated With Body Weight Training on Functional Capacity and Body Composition in Inactive Older People.

Marocolo M, Ide B, Simim M, Leitao L, Oranchuk D, Santos C Front Physiol. 2021; 12:719075.

PMID: 34335314 PMC: 8322646. DOI: 10.3389/fphys.2021.719075.

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