Long-term resistance training improves force and unloaded shortening velocity of single muscle fibres of elderly women.
Four elderly women (78 +/- 4.3 years) were resistance trained (RT) for one year and needle biopsies of the vastus lateralis muscle were taken pre- and post-RT. A training intensity of 60% one-repetition maximum (1RM) was adopted for the entire duration of the study. Following RT, significant gain in isometric force of the quadriceps muscles was observed and MHC isoform distribution of vastus lateralis muscle showed a very significant shift from MHC-1 and MHC-2X towards MHC-2A, i.e. a bi-directional shift. A large population (n = 310) of individual skinned muscle fibres were dissected from biopsy samples and used for determination of cross-sectional area (CSA), specific force (Po/CSA) and unloaded shortening velocity (Vo) at 12 degrees C and maximum activation. Fibres were classified on the basis of their MHC isoform content determined by SDS-PAGE in three pure fibre types (1, 2A and 2X) and two hybrid fibre types (1-2A and 2AX). Whereas the CSA of individual muscle fibres did not change, Po/CSA was significantly higher in both type 1 and type 2A fibres post training. Vo of type 1 fibres was significantly higher post-training, whereas no change in Vo was observed in type 2A fibres. The number of pure type 2X fibres was very low especially post-training and did not enable a statistically significant comparison. The data suggest that in elderly women moderate and prolonged RT: (1) can determine similar adaptations in MHC distribution of skeletal muscle to those expected in young subjects; (2) can improve function of muscle fibres.
Parente
Valeria
V
Department of Experimental Medicine, Human Physiology unit, and Interuniversity Institute of Miology, University of Pavia, Via Forlanini 6, 27100 Pavia, Italy.
D'Antona
Giuseppe
G
Adami
Raffaella
R
Miotti
Danilo
D
Capodaglio
Paolo
P
De Vito
Giuseppe
G
Bottinelli
Roberto
R
D000222:Adaptation, Physiological; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D009119:Muscle Contraction; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000502:physiology*; D053580:Muscle Strength; D018995:Myosin Heavy Chains / Q000378:metabolism; D020033:Protein Isoforms; D052097:Quadriceps Muscle / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D055070:Resistance Training
D020033:Protein Isoforms; D018995:Myosin Heavy Chains