title: Effect of very low-intensity resistance training with slow movement on muscle size and strength in healthy older adults.
abstract: We previously reported that low-intensity [50% of one repetition maximum (1RM)] resistance training with slow movement and tonic force generation (LST) causes muscle hypertrophy and strength gain in older participants. The aim of this study was to determine whether resistance training with slow movement and much more reduced intensity (30%1RM) increases muscle size and strength in older adults. Eighteen participants (60-77 years) were randomly assigned to two groups. One group performed very low-intensity (30% 1RM) knee extension exercise with continuous muscle contraction (LST: 3-s eccentric, 3-s concentric, and 1-s isometric actions with no rest between each repetition) twice a week for 12 weeks. The other group underwent intermitted muscle contraction (CON: 1-s concentric and 1-s eccentric actions with 1-s rest between each repetition) for the same time period. The 1RM, isometric and isokinetic strengths, and cross-sectional image of the mid-thigh obtained by magnetic resonance imaging were examined before and after the intervention. LST significantly increased the cross-sectional area of the quadriceps muscle (5.0%, P<0.001) and isometric and isokinetic knee extension strengths (P<0.05). CON failed to increase muscle size (1.1%, P = 0.12), but significantly improved its strength (P<0.05). These results indicate that even if the intensity is as low as 30% 1RM, LST can increase muscle size and strength in healthy older adults. The large total contraction time may be related to muscle hypertrophy and strength gain. LST would be useful for preventing sarcopenia in older individuals.
authors.affiliation: Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Tokyo, Japan.
authors.forename: Yuya
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Madarame
authors.forename: Riki
authors.initials: R
authors.lastname: Ogasawara
authors.forename: Koichi
authors.initials: K
authors.lastname: Nakazato
authors.forename: Naokata
authors.initials: N
authors.lastname: Ishii
mesh_terms: D000200:Action Potentials; D000367:Age Factors; D000368:Aged; D000375:Aging; D015415:Biomarkers / Q000097:blood; D001794:Blood Pressure; D004576:Electromyography; D005260:Female; D006801:Humans; D006984:Hypertrophy; D007564:Japan; D019344:Lactic Acid / Q000097:blood; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000502:physiology*; D009929:Organ Size; D055070:Resistance Training / Q000379:methods*; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D019344:Lactic Acid
keywords: Sarcopenia; ageing; elderly; muscle hypertrophy; strength training