Age-related changes in motor unit firing pattern of vastus lateralis muscle during low-moderate contraction

• Published in: AGE 2016-06, Vol.38 (3), p.48-48, Article 48
• Main Authors: Watanabe, Kohei, Holobar, Aleš, Kouzaki, Motoki, Ogawa, Madoka, Akima, Hiroshi, Moritani, Toshio
• Format: Article
• Language: English
• Subjects: Adult; Age; Aged; Aged, 80 and over; Aging; Aging - physiology; Anatomy & physiology; Biomedical and Life Sciences; Cell Biology; Comparative analysis; Electrodes; Electromyography; Environmental studies; Experiments; Geriatrics/Gerontology; Human body; Humans; Isometric Contraction - physiology; Laboratories; Life Sciences; Male; Men; Middle Aged; Molecular Medicine; Muscle Fatigue - physiology; Muscle strength; Muscle Strength - physiology; Muscular system; Older people; Physical fitness; Quadriceps Muscle - physiology; Recruitment; Recruitment, Neurophysiological - physiology; Statistical analysis; Young adults
• ISSN: 0161-9152; 2509-2715; 1574-4647; 2509-2723
• DOI: 10.1007/s11357-016-9915-0

Age-related changes in motor unit activation properties remain unclear for locomotor muscles such as quadriceps muscles, although these muscles are preferentially atrophied with aging and play important roles in daily living movements. The present study investigated and compared detailed motor unit firing characteristics for the vastus lateralis muscle during isometric contraction at low to moderate force levels in the elderly and young. Fourteen healthy elderly men and 15 healthy young men performed isometric ramp-up contraction to 70 % of the maximal voluntary contractions (MVC) during knee extension. Multichannel surface electromyograms were recorded from the vastus lateralis muscle using a two-dimensional grid of 64 electrodes and decomposed with the convolution kernel compensation technique to extract individual motor units. Motor unit firing rates in the young were significantly higher (~+29.7 %) than in the elderly ( p