Zachary M Gillen1, Terry J Housh2, Richard J Schmidt2, Trent J Herda3, Rafael J De Ayala4, Marni E Shoemaker5, Joel T Cramer5. 1. Department of Kinesiology, Mississippi State University, 236 McCarthy Gymnasium, Mississippi State, MS, 39762, USA. zmg43@msstate.edu. 2. Department of Nutrition & Health Sciences, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA. 3. Department of Health, Sport, and Exercise Sciences, University of Kansas, Lawrence, KS, 66045, USA. 4. Department of Educational Psychology, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA. 5. College of Health Sciences, The University of Texas at El Paso, El Paso, TX, 79968, USA.
Abstract
PURPOSE: The purpose of this study was to compare measurements of muscle strength, size, and activation of the forearm flexors in pre- and post-pubescent males and females. METHODS: Forty pre-pubescent (mean ± 95% confidence interval, age = 9.79 ± 0.35 years, n = 10 males, n = 10 females) and post-pubescent (age = 17.23 ± 0.58 years, n = 10 males, n = 10 females) youth participated. Subjects completed maximal voluntary isometric contractions (MVICs) of the forearm flexors, and submaximal isometric step muscle actions at 30, 50, and 70% of the peak MVIC. Percent voluntary activation (VA) was quantified during all isometric muscle actions. Forearm flexor (biceps brachii and brachialis) muscle cross-sectional area (CSA) was quantified from ultrasound images. RESULTS: MVIC strength was expressed in absolute terms and normalized to CSA. Post-pubertal males were 130% stronger, had 101% greater CSA, and 17% greater maximal VA than pre-pubertal males, while post-pubertal females were 72% stronger, had 54% greater CSA, and 23% greater maximal VA than pre-pubertal females. When MVIC strength was normalized to CSA, the post-pubertal males were still 15% stronger than the pre-pubertal males, while the post-pubertal females were only 12% stronger than the pre-pubertal females. The responses for VA across intensity reflected differences in muscle activation strategies between pre- and post-pubertal males and females. CONCLUSION: These results suggest that muscle size may account for a greater proportion of the growth and development-related differences in strength among males, while females may be more affected by changes in muscle activation. Regardless of sex, changes in muscle size and neuromuscular function influence strength increases during growth and development.
PURPOSE: The purpose of this study was to compare measurements of muscle strength, size, and activation of the forearm flexors in pre- and post-pubescent males and females. METHODS: Forty pre-pubescent (mean ± 95% confidence interval, age = 9.79 ± 0.35 years, n = 10 males, n = 10 females) and post-pubescent (age = 17.23 ± 0.58 years, n = 10 males, n = 10 females) youth participated. Subjects completed maximal voluntary isometric contractions (MVICs) of the forearm flexors, and submaximal isometric step muscle actions at 30, 50, and 70% of the peak MVIC. Percent voluntary activation (VA) was quantified during all isometric muscle actions. Forearm flexor (biceps brachii and brachialis) muscle cross-sectional area (CSA) was quantified from ultrasound images. RESULTS: MVIC strength was expressed in absolute terms and normalized to CSA. Post-pubertal males were 130% stronger, had 101% greater CSA, and 17% greater maximal VA than pre-pubertal males, while post-pubertal females were 72% stronger, had 54% greater CSA, and 23% greater maximal VA than pre-pubertal females. When MVIC strength was normalized to CSA, the post-pubertal males were still 15% stronger than the pre-pubertal males, while the post-pubertal females were only 12% stronger than the pre-pubertal females. The responses for VA across intensity reflected differences in muscle activation strategies between pre- and post-pubertal males and females. CONCLUSION: These results suggest that muscle size may account for a greater proportion of the growth and development-related differences in strength among males, while females may be more affected by changes in muscle activation. Regardless of sex, changes in muscle size and neuromuscular function influence strength increases during growth and development.
Authors: Nathaniel D M Jenkins; Terry J Housh; Samuel L Buckner; Haley C Bergstrom; Kristen C Cochrane; Ethan C Hill; Cory M Smith; Richard J Schmidt; Glen O Johnson; Joel T Cramer Journal: J Strength Cond Res Date: 2016-08 Impact factor: 3.775
Authors: Michael F Bergeron; Margo Mountjoy; Neil Armstrong; Michael Chia; Jean Côté; Carolyn A Emery; Avery Faigenbaum; Gary Hall; Susi Kriemler; Michel Léglise; Robert M Malina; Anne Marte Pensgaard; Alex Sanchez; Torbjørn Soligard; Jorunn Sundgot-Borgen; Willem van Mechelen; Juanita R Weissensteiner; Lars Engebretsen Journal: Br J Sports Med Date: 2015-07 Impact factor: 13.800
Authors: Zachary M Gillen; Marni E Shoemaker; Brianna D McKay; Nicholas A Bohannon; Sydney M Gibson; Joel T Cramer Journal: Eur J Appl Physiol Date: 2019-05-13 Impact factor: 3.078