title: Muscle activity during daily life in the older people.
abstract: BACKGROUND
  Daily muscle activity is important for functional independence. This study examined muscle activity patterns during normal daily life and simulated daily tasks and compared muscle activity and energy consumption during active and passive transport tasks in older adults.
  
  
  METHODS
  Nine volunteers (70 ± 6 years) were measured for quadriceps and hamstring muscle activity (EMG) during normal daily life, treadmill walking, and during passive and active transport tasks. EMG was normalized to that recorded during maximal voluntary contraction (MVC). Oxygen uptake (VO2) was measured during treadmill and transport tasks.
  
  
  RESULTS
  During daily life the mean EMG amplitude was 5.9 ± 2.4 % of EMGMVC, activity time was 187 ± 43 min and the longest continuous inactivity periods were 20.9 ± 10.0 min. During stair ascend the peak EMG activity was 120 % of EMGMVC and the peak VO2 values were only about 70 % of VO2max. One kilometer walk consumed 3.5 times more energy than passive transport by bus, and using stairs consumed 11.7 times more energy than using an elevator.
  
  
  CONCLUSIONS
  In daily life, older adults use only a small fraction of muscle's maximal capacity and have long continuous inactivity periods. Negotiating stairs produce significant load to neuromuscular, but not to cardiovascular system, thus providing an effective strength training stimulus.
authors.affiliation: Exercise Health and Technology Center, Department of Physical Education, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Room 103, Guangming Stadium, No. 800 Dongchuan Road, Minhang District, Shanghai, 200240, China. olli.tikkanen@sjtu.edu.cn.|Research and Training Institute ReTI Foundation, Espoo, Finland. olli.tikkanen@sjtu.edu.cn.|Fibion Inc., Jyväskylä, Finland. olli.tikkanen@sjtu.edu.cn.|Neuromuscular Research Center, Department of Biology of Physical Activity, University of Jyvaskyla, Jyväskylä, Finland. olli.tikkanen@sjtu.edu.cn.
authors.forename: Olli
authors.initials: O
authors.lastname: Tikkanen
authors.affiliation: Gerontology Research Center, Department of Health Sciences, University of Jyvaskyla, Jyväskylä, Finland.
authors.forename: Sarianna
authors.initials: S
authors.lastname: Sipilä
authors.affiliation: Neuromuscular Research Center, Department of Biology of Physical Activity, University of Jyvaskyla, Jyväskylä, Finland.
authors.forename: Anna-Stina
authors.initials: AS
authors.lastname: Kuula
authors.affiliation: Neuromuscular Research Center, Department of Biology of Physical Activity, University of Jyvaskyla, Jyväskylä, Finland.
authors.forename: Arto
authors.initials: A
authors.lastname: Pesola
authors.affiliation: Neuromuscular Research Center, Department of Biology of Physical Activity, University of Jyvaskyla, Jyväskylä, Finland.
authors.forename: Piia
authors.initials: P
authors.lastname: Haakana
authors.affiliation: Neuromuscular Research Center, Department of Biology of Physical Activity, University of Jyvaskyla, Jyväskylä, Finland.
authors.forename: Taija
authors.initials: T
authors.lastname: Finni
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D004576:Electromyography; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology*; D055070:Resistance Training; D016138:Walking
keywords: Aging; Electromyography; Energy expenditure; Independent living; Physical activity