The effect of exercise hypertrophy and disuse atrophy on muscle contractile properties: a mechanomyographic analysis

To determine whether mechanomyographic (MMG) determined contractile properties of the biceps brachii change during exercise-induced hypertrophy and subsequent disuse atrophy.Healthy subjects (mean\ua0±\ua0SD, 23.7\ua0±\ua02.6\ua0years, BMI 21.8\ua0±\ua02.4, n\ua0=\ua019) performed unilateral biceps curls (9 sets\ua0×\ua012 repetitions, 5 sessions per week) for 8\ua0weeks (hypertrophic phase) before ceasing exercise (atrophic phase) for the following 8\ua0weeks (non-dominant limb; treatment, dominant limb; control). MMG measures of muscle contractile properties (contraction time; T c, maximum displacement; D max, contraction velocity; V c), electromyographic (EMG) measures of muscle fatigue (median power frequency; MPF), strength measures (maximum voluntary contraction; MVC) and measures of muscle thickness (ultrasound) were obtained.Two-way repeated measures ANOVA showed significant differences (P\ua