Effects of Aging on Seniors' Bodies
The cardiopulmonary system is composed of the heart, lungs, arteries and veins. Every activity from taking a nap to exercising vigorously requires a well-functioning cardiopulmonary system. As you age:
Your cardiac output decreases by about 30% between the ages of 20 and 80. Cardiac output is a function of heart rate and stroke volume, how much blood your heart pumps per beat. While your maximum HR inevitably declines, through exercise you can maintain your ability to sustain a reasonably high HR and slow the decrease in the elasticity of your heart, which is what reduces stroke volume. In fact, with moderate-intensity exercise you can improve your maximal oxygen uptake by 20-30% over a sedentary lifestyle, which is comparable to the increases observed in younger subjects. Exercise capacity, the ability of the heart to support a high level of exertion, has been shown to be a stronger predictor of mortality than hypertension, smoking and diabetes!
When exercising, getting enough oxygen depends more on breathing more frequently rather than the depth of breathing, due to the decreased elasticity of the lungs, increased stiffness of the chest walls and weakening of the respiratory muscles. However, with training, improvements in ventilation take place and pulmonary function doesn't seem to be a limiting factor for physical activity.
Flow of blood to the limbs is reduced at rest in older individuals; however, fortunately the ability to deliver sufficient oxygenated blood during exercise is not affected, provided that you keep exercising.
Bottom line: If you exercise regularly and consistently, then you can significantly slow the aging process in the cardiovascular system, which will continue to deliver enough oxygenated blood to the muscles to support more exercise, whether you are cycling for health, overall fitness or for performance!
The musculoskeletal system includes all of the skeletal muscles that move our bodies in different ways. As you age:
Your muscles atrophy. The cross-sectional area of your muscle fibers decreases, resulting in a loss of strength. You have two types of fibers: slow-twitch (ST), which fire slowly and have great endurance, and fast-twitch (FT), which fire explosively when you need power. You differentially lose muscle mass in the FT fibers because as you age you tend not to do activities that require a lot of power. Even though you have a greater proportion of ST muscles due to differential atrophy, your endurance is not enhanced. (ST and FT refer to how rapidly the fibers contract, not your cadence.)
Unfortunately, as your muscles atrophy from less use, they are replaced by fat and connective tissue.
However, the rate of atrophy can be slowed with exercise, and most of it can even be reversed with resistance training! Note that only the muscles that you train regularly retain or regain muscle size. Progressive resistance training has the same effects on the muscles of nonagenarians as it does on 25-year-olds!
In your body different metabolic pathways produce energy, and the particular pathway(s) used at any given time depend on the fuel source and the intensity of activity. These pathways use enzymes to produce energy, and with aging the production of the different enzymes decreases; however, with exercise the enzymes available increases!
Bottom line: Through regular resistance exercise you keep your muscles from atrophying and keep your metabolic pathways functioning at a sufficient level. Thus, muscle strength doesn't have to be a limiter to your exercise for health or for performance.
The nervous system includes the Central Nervous System (CNS) and the Peripheral Nervous System (PNS)
The CNS is made up of your brain and the brain stem, the vital link between your brain and the spinal cord. Your brain receives sensory inputs from all parts of your body and makes decisions, conscious and unconscious, about how to respond. Your brain starts to shrink in your 30s, and its weight can decrease by about 10% by the time you are 90. Fortunately, physical activity may slow the progress of tissue loss in the brain.
The PNS includes the nerve receptors throughout the body that send messages to the brain, the motor units that fire in your muscles, telling them to contract, and the nerve pathways between all of this and the brain. As you age it takes longer for signals to travel both directions on the nerve pathways. This doesn't appear to affect functionality. However, you have a striking decline in the number of motor units beginning in your 70s.
Power and pedaling economy on the bike are the result of not only aerobic capacity and leg strength, but also neuromuscular facilitation, the ability of the body to coordinate precisely via the motor units the contraction of individual muscle fibers. Even if you do resistance training to prevent atrophy, later in life you slowly lose power as a result of the loss of motor units.
Your reaction time slows, too, as a result the loss of motor units and slower conductance of nerve signals, and may be exacerbated by the atrophy of FT fibers. You can't sprint as fast and, more importantly, this slower reaction time has consequences for activities of daily living. Suppose your foot encounters something unexpected. It takes slightly longer for the message to get to your brain, your brain to process the data and for the instructions to get back to your leg and foot. As a result, you may fall.
Your posture may get worse as you age, in part because of increasing stiffness but also because of the decline of the nervous system that controls your posture.
Physical activity may also retard the degradation of the conductance of nerve signals as well as a recovery from injury.
Bottom line: If you continue to exercise, you can slow the aging of your nervous system, which will be adequate to support your exercise program and activities of daily living for decades to come!
Anti-Aging 12 Ways to You Can Slow the Aging Process. 106 pages for $14.99 from RoadBikeRider.com
Examples of Older Cyclists
Elizabeth Wicks broke the womens age 65 to 69 record at Calvins 12-Hour Challenge in 2013 and the W70-74 record in 2014. I coached Wicks. Here is her 2013 training program.
Peter Lekisch was the first 60-year-old rider to finish the solo Race Across AMerica in 2001 in 12 days 20 hours 50 minutes. I had the pleasure of coaching Peter. Here is his training program.
More Information for Seniors
Cycling Past 50. A 4-article bundle of 98 pages for older cyclists for just $15.96, a 20% discount from RoadBikeRider.com. The bundle includes:
- Healthy Cycling Past 50. What happens as you age and how to incorporate cycling and other exercise activities into your daily life to stay healthy and active for many years. Includes three balanced exercise programs for older cyclists.
- Off-Season Conditioning Past 50. How to best work on your off-season conditioning given the physiological changes of growing older. Includes two 12-week programs for older cyclists.
- Healthy Nutrition Past 50. What an older cyclist should eat and drink to support both a healthy lifestyle and continuing performance.
- Performance Cycling Past 50. How older cyclists can train to achieve more specific cycling goals given the physiological changes of aging.
Cycling Past 60. A 2-article bundle of 47 pages for senior cyclists for just $8.98, a 10% discount from RoadBikeRider.com. The bundle includes:
- Cycling Past 60, Part 1: For Health. If a senior exercises correctly, you can slow the effects of aging; if you exercise incorrectly, you can speed up aging. Includes three well-balanced exercise programs for senior cyclists.
- Cycling Past 60, Part 2: For Recreation. Builds on the information in Part 1 and uses the concept of Athletic Maturity to design six more rigorous programs for more athletically mature seniors.
Cycling Past 50, 60 and Beyond. A 3-article bundle of 100 pages for seniors for just $13.50, a 20% discount from RoadBikeRider.com. The bundle includes:
- Fit for Life. The article shows how you can exercise in different ways to be fitter for life as a senior and have fun. It provides a variety of exercise options available to you to strengthen your body's functions that keep you alive and help to keep you fit for life, including the aerobic, skeletal, muscular, neural, core and balance systems.
- Peak Fitness
The article contains four specific programs for seniors to improve fitness in one or more of the following ways: Improved Endurance, More Power, Faster Speed and / or Higher Aerobic Capacity (VO2 max.)
- Training with Intensity. The article describes five progressively harder levels of training for seniors and gives 3 to 5 examples each of structured and unstructured workouts for each level of training, a total of almost 40 workouts.
Other articles by Coach Hughes