MEDI221 2023 Intro to Lifespan PDF

Exercise across the lifespan An introduction to age-related changes in exercise capacity Dr Natalie Kwai Senior Lecturer  What you should be able to do after this L...

Exercise across the lifespan An introduction to age-related changes in exercise capacity Dr Natalie Kwai Senior Lecturer  What you should be able to do after this Lecture: Describe briefly key physiological Learning changes that occur across the lifespan that can affect exercise capacity Outcomes Describe age-peak performance and factors contributing to this relationship Describe briefly physical activity patterns across the lifespan Recommended readings Fragala, M.S. (2015). The Physiology of Aging and Exercise. In: Sullivan, G., Pomidor, A. (eds) Exercise for Aging Adults. Springer, Cham. https://doi.org/10.1007/978-3-319-16095-5_1 Organ-Specific Physiological Responses to Acute Physical Exercise and Long-Term Training in Humans Ilkka Heinonen, Kari K. Kalliokoski, Jarna C. Hannukainen, Dirk J. Duncker, Pirjo Nuutila, and Juhani Knuuti Physiology 2014 29:6, 421-436 Allen, S.V., Hopkins, W.G. Age of Peak Competitive Performance of Elite Athletes: A Systematic Review. Sports Med 45, 1431–1441 (2015). https://doi.org/10.1007/s40279-015-0354-3 Acute response to exercise Many systems involved to maximise exercise capacity Acute physiological response to exercise: - Liberation of stored fuels - Nutrient and Oxygen delivery = ATP - Waste removal - Maintenance of body temp Many different organs systems involved Appropriate and efficient function of different systems required Across the lifespan Physiological and anatomical systems change over time Infancy Young child Adolescence – young adult Elderly Development Peak physiological condition Decline Varying effects on exercise capacity (infancy) and young children Development: systems still forming/optimising Cardiovascular system - smaller hearts and reduced stroke volume  higher HR Metabolic demand Respiratory system - Higher in children due - Smaller lung volumes and lower respiratory muscle requirements for development function - Limit VE and therefore O2 exchange  higher breathing frequency - Greater chest compliance How might these different Musculoskeletal system changes affect a child’s exercise - Higher proportion of slow twitch muscle fibers capacity? - Reduced bone density with active growth plates Thermoregulation (attributed to by cv and nervous system) - Reduced capacity for heat transfer  (infancy) and young children Development: systems still forming/optimising Physiological differences between adults and children Children - Oxygen consumption is higher (~10-30%) at the same submaximal level - Lower exercise economy - High SA/M ratio - Shorter stride lengths/greater stride frequency - Lower ventilatory efficiency = Exercise is more stressful! - Lower absolute aerobic power values than adults - Poorer anaerobic power  potentially linked to lower density of proteins involved in anaerobic pathways for metabolism (e.g. phosphofructokinase) Young adult Systems formed – peak physical condition Peak physical condition occurs between adolescence up to 30yrs - Physiological systems are fully developed and at their most efficient Peak performance not directly linked to age and is not the same across sports Photo by August Phlieger on Unsplash Older adults Many systems and their functions affected Age-related alterations in the neuromuscular and cardiovascular systems = greatest impact on physical function. Biological aging does not always align with chronological aging. Disability and aerobic physical frailty are related and have profound effects upon outcomes important to older adults, such as nursing home residence and mortality. Physiologic aging mimics “disuse” syndromes. Exercise reverses many physiological changes commonly associated with aging. Disuse may actually be a key cause of primary aging. Age-peak performance Age at which peak performance is reached Peak performance = Physical capacity + Cognitive skills/experience Age at which peak performance is reached varies from sport to sport Age-peak performance Peak performance occurs later in endurance events compared to explosive sprint Females Males Allen and Hopkins (2015) Why endurance athletes peak later? Age-peak performance Why endurance athletes peak later? Accumulating improvements in cognitive and/or experiential capacities that offset the inevitable plateau in physical ability. marathon running, Ironman triathlon, ultra- endurance cycling and cyclo-cross Experiential/cognitive edge 1. Pacing 2. Nutritional strategies 3. Anticipating and dealing with environmental conditions 4. Mental resilience Physical Activity Guidelines AIHW Recommendations (2018)  Summary Where it all comes together… There are numerous physiological differences between older v younger subjects that explain average fitness and responses to exercise interventions e.g. CV changes, musculoskeletal changes, nervous system changes etc. Development in children/adolescents results in alterations to exercise capacity Peak performance is typically reached in young adulthood Age-peak performance is not as simple and peak performance is affected by peak physical capacity and mental/experiential maturity – endurance sport athletes peak at higher ages Older adults experience a reduced efficiency of a number of physiological processes which can impair exercise capacity Physical activity guidelines are poorly met across the lifespan in Australia