Skeletal muscle mitochondrial capacity (mito), tissue blood flow (BF) capacity, and oxygen exchange capacity (e.g., DO2) appear to be well matched. The different skeletal muscle fiber types and muscle remodeled, due to inactivity >(e.g., related to aging or disease) or exercise training, exhibit widely differing aerobics capacities (V̇O2max). Yet, there are remarkably coordinated alterations in these 3 parameters in each of these conditions. With such a balance, there is likely shared control among these parameters in limiting (V̇O2max) of muscle, although this is a matter of considerable debate. The reduction in aerobic capacity in elderly can be improved by submaximal aerobic exercise training; this is related to increases in muscle mitochondria concentration and capillarity, but probably not BF capacity, as this is limited by central cardiovascular function. Thus, exercise-induced biochemical adaptations and angiogenesis occur in the elderly. The increase in muscle capillarity likely contributes to the increased oxygen exchange capacity, typical of endurance type training. The increase in [mito] appears essential to realize the increased in muscle V̇O2max with training and amplifies the rate-limiting influence of the muscle’s oxygen exchange capacity. Further, vascular remodeling induced by exercise in the elderly could be effective at improving flow capacity, if limited by peripheral obstruction. Thus, the limits to aerobic function specific to aged muscle appear most influenced by inactivity, whereas central cardiovascular changes impact whole body performance. Some may consider the aged myocyte as a small, inactive, normal myocyte in need of activity!
Ronald L. Terjung, Ryszard Zarzeczny and H.T. Yang
Xiaolin Yang, Irinja Lounassalo, Anna Kankaanpää, Mirja Hirvensalo, Suvi P. Rovio, Asko Tolvanen, Stuart J.H. Biddle, Harri Helajärvi, Sanna H. Palomäki, Kasper Salin, Nina Hutri-Kähönen, Olli T. Raitakari and Tuija H. Tammelin
Background: The purpose of this study was to examine trajectories of leisure-time physical activity (LTPA) and television-viewing (TV) time and their associations in adults over 10 years. Methods: The sample comprised 2934 participants (men, 46.0%) aged 24–39 years in 2001 and they were followed up for 10 years. LTPA and TV time were assessed using self-report questionnaires in 2001, 2007, and 2011. Longitudinal LTPA and TV-time trajectories and their interactions were analyzed with mixture modeling. Results: Three LTPA (persistently highly active, 15.8%; persistently moderately active, 60.8%; and persistently low active, 23.5%) and 4 TV time (consistently low, 38.6%; consistently moderate, 48.2%; consistently high, 11.7%; and consistently very high, 1.5%) trajectory classes were identified. Persistently highly active women had a lower probability of consistently high TV time than persistently low-active women (P = .02), whereas men who were persistently highly active had a higher probability of consistently moderate TV time and a lower probability of consistently low TV time than their persistently low-active counterparts (P = .03 and P = .01, respectively). Conclusions: Maintaining high LTPA levels were accompanied by less TV over time in women, but not in men. The associations were partially explained by education, body mass index, and smoking.
Salomé Aubert, Joel D. Barnes, Chalchisa Abdeta, Patrick Abi Nader, Ade F. Adeniyi, Nicolas Aguilar-Farias, Dolores S. Andrade Tenesaca, Jasmin Bhawra, Javier Brazo-Sayavera, Greet Cardon, Chen-Kang Chang, Christine Delisle Nyström, Yolanda Demetriou, Catherine E. Draper, Lowri Edwards, Arunas Emeljanovas, Aleš Gába, Karla I. Galaviz, Silvia A. González, Marianella Herrera-Cuenca, Wendy Y. Huang, Izzeldin A.E. Ibrahim, Jaak Jürimäe, Katariina Kämppi, Tarun R. Katapally, Piyawat Katewongsa, Peter T. Katzmarzyk, Asaduzzaman Khan, Agata Korcz, Yeon Soo Kim, Estelle Lambert, Eun-Young Lee, Marie Löf, Tom Loney, Juan López-Taylor, Yang Liu, Daga Makaza, Taru Manyanga, Bilyana Mileva, Shawnda A. Morrison, Jorge Mota, Vida K. Nyawornota, Reginald Ocansey, John J. Reilly, Blanca Roman-Viñas, Diego Augusto Santos Silva, Pairoj Saonuam, John Scriven, Jan Seghers, Natasha Schranz, Thomas Skovgaard, Melody Smith, Martyn Standage, Gregor Starc, Gareth Stratton, Narayan Subedi, Tim Takken, Tuija Tammelin, Chiaki Tanaka, David Thivel, Dawn Tladi, Richard Tyler, Riaz Uddin, Alun Williams, Stephen H.S. Wong, Ching-Lin Wu, Paweł Zembura and Mark S. Tremblay
Background: Accumulating sufficient moderate to vigorous physical activity is recognized as a key determinant of physical, physiological, developmental, mental, cognitive, and social health among children and youth (aged 5–17 y). The Global Matrix 3.0 of Report Card grades on physical activity was developed to achieve a better understanding of the global variation in child and youth physical activity and associated supports. Methods: Work groups from 49 countries followed harmonized procedures to develop their Report Cards by grading 10 common indicators using the best available data. The participating countries were divided into 3 categories using the United Nations’ human development index (HDI) classification (low or medium, high, and very high HDI). Results: A total of 490 grades, including 369 letter grades and 121 incomplete grades, were assigned by the 49 work groups. Overall, an average grade of “C-,” “D+,” and “C-” was obtained for the low and medium HDI countries, high HDI countries, and very high HDI countries, respectively. Conclusions: The present study provides rich new evidence showing that the situation regarding the physical activity of children and youth is a concern worldwide. Strategic public investments to implement effective interventions to increase physical activity opportunities are needed.