title: Resistance training of long duration modulates force and unloaded shortening velocity of single muscle fibres of young women.
abstract: The aim of the present study was to clarify the impact of long term (1 year) resistance training (RT) on structure and function of single muscle fibres of vastus lateralis in young female subjects. Five young women (age: 25.4+/-6.2 year) performed exercise sessions at 60% of single subject own repetition maximum (1 RM) 1h twice a week. Maximum voluntary force was determined pre- and post-RT and was found to significantly increase post-RT ensuring a successful impact of RT on muscle performance in vivo. Needle muscle biopsy samples were obtained both pre- and post-RT and the following determinations were performed: myosin heavy chain isoform (MHC) distribution of the whole muscle samples by SDS-PAGE; cross sectional area (CSA), specific force (Po/CSA) and maximum shortening velocity (Vo) of a large population (n=358) of single skinned muscle fibres classified on the basis of MHC isoform composition by SDS-PAGE. The results suggest that the long duration of RT can determine a significant increase in specific force (Po/CSA) and unloaded shortening velocity (Vo) of single muscle fibres in female subjects, whereas no muscle fibre hypertrophy and no shift in MHC isoform content was observed.
authors.affiliation: Department of Experimental Medicine, Human Physiology Unit, and Interuniversity Institute of Miology, University of Pavia, Via Forlanini 6, 27100 Pavia, Italy.
authors.forename: Orietta
authors.initials: O
authors.lastname: Pansarasa
authors.forename: Chiara
authors.initials: C
authors.lastname: Rinaldi
authors.forename: Valeria
authors.initials: V
authors.lastname: Parente
authors.forename: Danilo
authors.initials: D
authors.lastname: Miotti
authors.forename: Paolo
authors.initials: P
authors.lastname: Capodaglio
authors.forename: Roberto
authors.initials: R
authors.lastname: Bottinelli
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D000328:Adult; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D008137:Longitudinal Studies; D009119:Muscle Contraction / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000166:cytology* / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D055070:Resistance Training / Q000379:methods*; D013314:Stress, Mechanical