title: Impact of maximal strength training on work efficiency and muscle fiber type in the elderly: Implications for physical function and fall prevention.
abstract: Although aging is typically associated with a decreased efficiency of locomotion, somewhat surprisingly, there is also a reduction in the proportion of less efficient fast-twitch Type II skeletal muscle fibers and subsequently a greater propensity for falls. Maximal strength training (MST), with an emphasis on velocity in the concentric phase, improves maximal strength, the rate of force development (RFD), and work efficiency, but the impact on muscle morphology in the elderly is unknown. Therefore we evaluated force production, walking work efficiency, and muscle morphology in 11 old (72±3years) subjects before and after MST of the legs. Additionally, for reference, the MST-induced morphometric changes were compared with 7 old (74±6years) subjects who performed conventional strength training (CST), with focus on hypertrophy, as well as 13 young (24±2years) controls. As expected, MST in the old improved maximal strength (68%), RFD (48%), and work efficiency (12%), restoring each to a level similar to the young. However, of importance, these MST-induced functional changes were accompanied by a significant increase in the size (66%) and shift toward a larger percentage (56%) of Type II skeletal muscle fibers, mirroring the adaptations in the hypertrophy trained old subjects, with muscle composition now being similar to the young. In conclusion, MST can increase both work efficiency and Type II skeletal muscle fiber size and percentage in the elderly, supporting the potential role of MST as a countermeasure to maintain both physical function and fall prevention in this population.
authors.affiliation: Department of Circulation and Medical Imaging, Faculty of Medicine, The Norwegian University of Science and Technology, Trondheim, Norway; Department of Medicine, University of Utah, Salt Lake City, UT, USA; Department of Research and Development, St. Olav's University Hospital, Trondheim, Norway. Electronic address: eivind.wang@ntnu.no.
authors.forename: Eivind
authors.initials: E
authors.lastname: Wang
authors.affiliation: Department of Circulation and Medical Imaging, Faculty of Medicine, The Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Stian Kwak
authors.initials: SK
authors.lastname: Nyberg
authors.affiliation: Department of Circulation and Medical Imaging, Faculty of Medicine, The Norwegian University of Science and Technology, Trondheim, Norway; Department of Physical Medicine and Rehabilitation, St.Olavs University Hospital, Trondheim, Norway.
authors.forename: Jan
authors.initials: J
authors.lastname: Hoff
authors.affiliation: Department of Medicine, University of Utah, Salt Lake City, UT, USA.
authors.forename: Jia
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Physical Medicine and Rehabilitation, St.Olavs University Hospital, Trondheim, Norway; Department of Clinical Medicine, Faculty of Medicine, The Arctic University of Norway, Trondheim, Norway.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Leivseth
authors.affiliation: Department of Physical Medicine and Rehabilitation, St.Olavs University Hospital, Trondheim, Norway; Department of Neuroscience, Faculty of Medicine, The Norwegian University of Science and Technology. Trondheim, Norway.
authors.forename: Tom
authors.initials: T
authors.lastname: Tørhaug
authors.affiliation: Department of Orthopedics, St.Olavs University Hospital, Trondheim, Norway.
authors.forename: Otto Schnell
authors.initials: OS
authors.lastname: Husby
authors.affiliation: Department of Circulation and Medical Imaging, Faculty of Medicine, The Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Jan
authors.initials: J
authors.lastname: Helgerud
authors.affiliation: Department of Medicine, University of Utah, Salt Lake City, UT, USA; Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA; Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, UT, USA.
authors.forename: Russell S
authors.initials: RS
authors.lastname: Richardson
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control; D000222:Adaptation, Physiological; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D004576:Electromyography; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D018656:Muscle Fibers, Fast-Twitch / Q000502:physiology*; D053580:Muscle Strength / Q000502:physiology*; D009664:Norway; D055070:Resistance Training / Q000379:methods*; D055815:Young Adult
keywords: Aging; Heavy resistance training; Rate of force development; Walking efficiency