Adapted from the “Summary of Typical Changes in Physiological Function and Body Composition with Advanced Age in Healthy Humans.” Variables Typical Change Functional Significance Regional blood flow. Leg blood flow is generally reduced at rest, submaximal, and maximal exercise. May influence exercise, activities of daily living, and BP regulation in old age. O2 extraction. Capacity for peripheral O2 is relatively maintained.
Systemic: Same at rest and during submaximal exercise; decreased slightly at maximal exercise. Thirst sensation decreases. Total body water declines with age.
Body fluid regulation.
May predispose to dehydration and impaired exercise tolerance in the heat.
Pulmonary Function
Ventilation.
Chest wall stiffens. Expiratory muscle strength decreases. Older adults adopt different breathing strategies during exercise. Work of breathing increases. Loss of alveoli and increased size of remaining alveoli; reduces surface area for O2 and CO2 exchange in the lungs.
Pulmonary aging not limiting to exercise.
Gas exchange.
Arterial blood gases are usually well-maintained up until maximal exercise.
Physical Function Capacities
Submaximal work efficiency.
Metabolic cost of walking at a given speed is increased. Work efficiency is preserved, but O2 debt may increase in sedentary older adults.
Implications for caloric cost and VO2 prediction in older adults.
Walking kinematics. Preferred walking speed is slow. Stride length is shorter; double limb support is longer. Increased gait variability. Age differences are exaggerated when balance is perturbed.
Implications for physical function and risk of falling.
Stair-climbing ability.
Maximal step height is reduced, reflects integrated measure of leg strength, coordinated muscle activation and dynamic balance.
Implications for mobility and physical demanding activities of daily living.
Body Composition/Metabolism
Height.
Height declines at approximately 1 cm per decade during the 40s and 50s and accelerates after age 60. Vertebral disks compress; thoracic curve becomes more pronounced. Weight steadily increases with age and stabilizes around age 70, then declines. Age-related changes in weight and BMI can mask fat gain/muscle loss.
Vertebral changes can impair mobility and other daily tasks.
Weight.
Large rapid weight loss in old age can indicate disease processes.
Fat-free mass (FFM). FFM declines 2 to 3 percent per decade from 30 to 70 years old. Losses of total body protein and potassium likely reflect the loss of metabolically active tissue (muscle).
FFM seems to be an important physiological regulator.
Muscle mass and size.
Total muscle mass declines from about 40 years old and accelerates after 65 to 70 years old. Legs lose muscle faster. Limb muscles exhibit reductions in fiber number and size. Bone mass peaks in the mid to late 20s. Bone mass density declines after age 40 and women have disproportionate loss of bone after menopause.
Loss of muscle mass results in reduced muscle speed/ power.
Bone density.
Osteoporosis elevates fracture risk.
Note . From Wojtek et al., 2009. HOW EXERCISE CAN COUNTERACT THE EFFECTS OF AGING AND PROMOTE GOOD HEALTH
In order to counteract aging’s impact on the body, it is important to participate in physical activity to support all body systems. Research shows that older adults who remain or become active have a significantly decreased risk of all-cause and cardiovascular mortality when compared with those who are more sedentary (McDermott & Mernitz, 2006). Additionally, those who start an exercise program later in life can significantly reduce risk factors even if they had a more sedentary lifestyle when they were younger (McDermott & Mernitz, 2006).
Strength and endurance training can help the body adapt to neuromuscular and cardiovascular changes (Cadore et al., 2014). Strength training can lead to muscle hypertrophy, as well as increase motor unit recruitment capacity and increase the rate of motor unit firing, which can lead to improved muscle strength and power (Cadore et al., 2014). Strength training can also improve muscle mass and power output in the frail elderly populations (Cadore et al., 2014). These changes are important in the aging adult because as we age, we experience a decline
Page 82
Book Code: PTNY3622B
EliteLearning.com/Physical-Therapy
Powered by FlippingBook