Related Experiment Video
Updated: Aug 19, 2026

Improving Strength, Power, Muscle Aerobic Capacity, and Glucose Tolerance through Short-term Progressive Strength Training Among Elderly People
Published on: July 5, 2017
ACTN3 genotype is associated with increases in muscle strength in response to resistance training in women
Priscilla M Clarkson1, Joseph M Devaney, Heather Gordish-Dressman
1Dept. of Exercise Science, Univ. of Massachusetts, Amherst, MA 01003, USA. clarkson@excsci.umass.edu
Abstract:
The alpha-actinin 3 (ACTN3) gene encodes a protein of the Z disk of myofibers, and a polymorphism of ACTN3 results in complete loss of the protein. The ACTN3 genotype (R577X) has been found to be associated with performance in Australian elite athletes (Yang N, MacArthur DG, Gulbin JP, Hahn AG, Beggs AH, Easteal S, and North K. Am J Hum Genet 73: 627-631, 2003). We studied associations between ACTN3 genotype and muscle size [cross-sectional area of the biceps brachii via magnetic resonance imaging (MRI)] and elbow flexor isometric (MVC) and dynamic [1-repetition maximum (1-RM)] strength in a large group of men (N = 247) and women (N = 355) enrolled in a 12-wk standardized elbow flexor/extensor resistance training program of the nondominant arm at one of eight study centers. We found no association between ACTN3 R577X genotype and muscle phenotype in men. However, women homozygous for the ACTN3 577X allele (XX) had lower baseline MVC compared with heterozygotes (P < 0.05) when adjusted for body mass and age. Women homozygous for the mutant allele (577X) demonstrated greater absolute and relative 1-RM gains compared with the homozygous wild type (RR) after resistance training when adjusted for body mass and age (P < 0.05). There was a trend for a dose-response with genotype such that gains were greatest for XX and least for RR. Significant associations were validated in at least one ethnic subpopulation (Caucasians, Asians) and were independent of training volume. About 2% of baseline MVC and of 1-RM strength gain after training were attributable to ACTN3 genotype (likelihood-ratio test P value, P = 0.01), suggesting that ACTN3 is one of many genes contributing to genetic variation in muscle performance and adaptation to exercise.
More Related Videos
07:40Impact of High-intensity Interval Exercise and Moderate-Intensity Continuous Exercise on the Cardiac Troponin T Level at an Early Stage of Training
Published on: October 10, 2019
08:48Adapted Resistance Training Improves Strength in Eight Weeks in Individuals with Multiple Sclerosis
Published on: January 29, 2016
Related Concept Videos
Exercise and Muscle Performance
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...
Alterations in Muscle Tone lll
Alterations in Muscle Tone ll
Actin Polymerization and Cell Motility
Actin cytoskeleton dynamics can produce pushing, pulling, and resistance forces that help the cell to migrate.
Cellular Adaptation II: Hypertrophy
Muscle Contraction