Major Questions w What is the effect of aging and training on body composition? w How are changes in strength and endurance affected by aging? w What changes occur to muscles with aging? w How does training affect biological aging and What is the difference between aging and physical activity? w What cardiovascular and respiratory changes occur with aging and What is the effect of training on these changes? w What is the trainability of older athletes for strength and endurance?
Overview • Biology of Aging: Major Theories • Scope and nature of the problem of muscle loss • Causes and Treatment of Sarcopenia • Recent Studies • Relation to Major Theories
Biology of Aging: Why do we age? • Cumulative Damage (Environment) • Inherited (Genetic, passive or programmed) • Gene x Environment interaction
Biology of Aging:Specific Mechanisms • Cellular damage • Free-Radical hypothesis • Oxidative stress • Mitochondrial Mutation • Somatic mutation • Lipid peroxidation • Glycation • Random vs. environment • Genetic Variation protecting
Biology of Aging:Specific Mechanisms • Cellular Repair • Replication senescence (Telomeres) • Hormones • Apoptosis • Genetic Variation modified
Biology of Aging:Specific Mechanisms • Calorie Restriction • Replication senescence (Telomeres) • Metabolic potential, Heart rate limit • Reduced environment exposure to mutagens • Genetic Variation modified
Biology of Aging:Specific Mechanisms • Variation in Lifespan between species • Species protected from predation tend to have longer maximal lifespans • Perhaps grandparents role in survival of grandchildren has enhanced selection of “longevity” genes (Active selection) • Studies of the genetic contribution to longevity in humans are confounded by the unanswerable question of whether a person is genetically predisposed or just dodged a lot of bullets • The bottom line is that our genes are selected based upon reproductive success and not our ability to resist the effects of aging
“Of Mice and Men” – Voluntary Wheel Running in Rats One of the most difficult things to determine is whether physiological deterioration with age is due to aging per se or to the dramatic decrease in daily activity levels. It is undoubtedly a combination of the two.
Relative body fat increases after maturity due to w Increased dietary intake of calories and/or w Decreased physical activity w Reduced ability to mobilize fat After age 30, fat-free mass decreases due to w Decreased muscle mass (decreasing testosterone levels) w Increased bone mineral loss w Decreased physical activity Body Composition and Aging: A Double Whammy
Body Composition and Training One of the important things about physical training as one ages is that it can help offset age-related loss of fat-free mass and gains in fat mass, i.e., the double whammy.
Strength Changes With Aging w Maximal strength decreases w Muscle mass decreases w Percentage of ST muscle fibers increases because of death of fast twitch alpha-motoneurons followed by reinnervation of the denervated fast muscle fibers by slow motoneurons, which converts the muscle fibers to ST w Total number and size of muscle fibers decreases w Nervous system response slows w Little change in oxidative enzyme capacity or number of capillaries
Number of motor units declines during aging - extensor digitorum brevis muscle of human beings AGE-ASSOCIATED ATROPHY DUE TO BOTH… Individual fiber atrophy (which may be at least partially preventable and reversible through exercise). Loss of fibers (which as yet appears irreversible). Campbell et al., (1973) J Neurol Neurosurg Psych 36:74-182.
Motor unit remodeling with aging Central nervous system Muscle Motor neuron loss AGING • Fewer motor units • More fibers/motor unit
Effects of Training on Strength While endurance training does not prevent the aging loss in muscle mass, resistance training can maintain or increase the muscle fiber cross-sectional area in older men and women.
Computed Tomography Scans of Arms of Three 57-Year-Old Men of Similar Body Weights Biceps Brachii M. Humerus Triceps Brachii M. Untrained Swim-Trained Strength-Trained
w Muscle blood flow decreases are offset in trained individuals by an increased submaximal a-vO2 difference – Cardiovascular Function and Aging w Aerobic capacity decreases about 1% per year after age 25 w Maximum heart rate decreases about 1 beat per year w Maximum stroke volume decreases, though it can be well maintained with training w Maximum cardiac output decreases
Maximal HR and Age Maximal heart rate can be estimated with the following equation: HRmax = [208 – 0.7 age]
LEG BLOOD FLOW DURING CYCLING Thus, the older athletes maintain oxygen consumption during increasing levels of exercise by increasing a-vO2diff to a greater extent than the younger athletes.
. w Qmax decreases due to decreased HRmax and SVmax. . w VO2max decreases due to reduced blood flow to active tissues because of reduced Qmax. . Cardiovascular Changes With Aging w HRmax decreases due to decreased sympathetic nervous system activity and changes in cardiac conduction. w SVmax decreases primarily due to increased total peripheral resistance (increased afterload).
. w VEmax decreases after maturity Respiratory Changes With Aging w Vital capacity (VC) and forced expiratory volume in 1 s (FEV1.0) decrease linearly with age w Residual volume (RV) increases w Total lung capacity (TLC) remains unchanged w RV:TLC increases (less air can be exchanged) w Elasticity in lung tissue and chest walls decreases, which is the primary mechanism for the above listed changes; there may also be a decreased function of the respiratory muscles
w Limitations in oxygen transport to the muscles (i.e., muscle blood flow)and a decreased a-vO2 difference are the main causes for reduced VO2max. – . Respiratory Aging and Performance w Endurance training in middle and older age reduces the loss of elasticity from the lungs. w The pulmonary ventilation capabilities of endurance-trained athletes are only slightly decreased with aging. w Arterial oxygen saturation does not decrease during strenuous exercise for normally active older adults.
. w Aging alone may not necessarily decrease VO2max; decreased daily activity levels also contribute. w When you keep intensity and volume of training high, your rate of decrease in SV and VO2max with aging slows, especially between ages 30 and 50 and less so after age 50. . Studies of Older Athletes w There are individual differences in the rate of decline with aging. w Prior training offers little advantage to endurance capacity later in life unless you stay active.
. Changes in VO2max With Aging Among Normally Active Men . Age VO2max % change from (years) (ml kg min ) 25 years . . -1 -1 25 47.7 35 43.1 -9.6 45 39.5 -17.2 52 38.4 -19.5 63 34.5 -27.7 75 25.5 -46.5
. VO2max Age Weight HRmax (years) (kg) (L/min) (ml · kg–1 · min –1) (beats/min) 21.3 63.9 4.41 69.0 189 (±1.6) (±2.2) (±0.09) (±1.4) (±6) 46.3 66.0 4.25 64.3 180 (±1.3) (±0.6) (±0.05) (±0.8) (±6) Note. Values are mean ± SE. Changes in Aerobic Capacity and Maximal Heart Rates With Aging in a Group of 10 Highly Trained Masters Distance Runners
. CHANGES IN VO2MAX WITH AGE
Aging alone might decrease cardiorespiratory fitness less than the deconditioning that occurs with inactivity, decreased activity, or decreased intensity of training. If body composition and physical activity are kept constant, VO2max decreases only 2% to 5% per decade, rather than the 10% per decade normally attributed to aging. . Aging versus Inactivity
Endurance exercise w Produces similar gains in healthy people regardless of their age, sex, or initial fitness level w Produces greater improvement in muscle oxidative enzyme activities than in younger endurance-trained people Resistance exercise w Produces increases in muscle strength and muscle hypertrophy Trainability of the Older Athlete
100-m freestyle CHANGES WITH AGE IN SWIMMING RECORDS
Best performances (s) Distance (m) 20 years 50 years Improvement (%) 50 27.2 26.5 2.6 100 62.7 60.3 3.8 200 147.8 137.7 6.8 400 318.8 288.9 9.4 1,500 1,403.0 1,227.0 12.5 Note. The best freestyle swimming (front crawl stroke) times were achieved at age 50, despite the fact that the swimmer was an accomplished collegiate swimmer at age 18 to 21 years. It is also interesting to mention that this swimmer trained by swimming about 1,500 m per day at age 20 and 2,500 m per day at age 50. Data from Ball State University, Human Performance Laboratory. Swimming Performances at Age 20 and 50 Years for a Male Masters Swimmer
CHANGES WITH AGE IN POWERLIFTING RECORDS U.S. National Masters records for males for total (bench, squat, and deadlift) – weight class(es)?