Fri 2 Jan 2009
Aging and the Endurance Athlete
Posted by Susan under Aging and Endurance, Blog, Physical Fitness
No Comments
Introduction:
In recent decades past, it has often been accepted that aging means lowered quality of life because of injury, disease and reduced cardiovascular endurance and strength. The accepted norm was to taper off on activity and accept the inevitable decline in health and athletic involvement after age forty. Runners are often told to quit running because it is “hard on the body”. As one approaches middle age, and sees a decline in athletic ability as compared to a much younger population, the question arises: Is it healthy to continue training hard into old age? There is a plethora of research involving the benefits of endurance training in aging gracefully. This paper will discuss studies which address the benefits of long term endurance training for the aging population on their immune systems, cardiovascular systems and exercise capacity.
Immune Function, Endocrine Function and VO2 Max Study
One major concern for the aging is the inevitable reduction in immune system health, leading to an increased risk of infection followed by high rates of disease, lowered quality of life and eventual death. It has been hypothesized that exercise may slow the rate of deterioration of the immune system.
Researchers, seeking to investigate the effects of exercise on the immune and endocrine systems, compared elderly male runners to normal sedentary elderly and young men (Arai, M. et al, 2006). A group of 20 recreational runners (aged 61-80); a group of healthy sedentary controls (aged 60-75) and 10 young healthy sedentary controls (aged 23-34) were studied. The sedentary groups had not been involved in any physical activity for more than 15 minutes 3 times a week for at least 2 years prior to the study. The group of runners ran an average of 38.7 miles per week for 21 to 25 years.
When tested to exhaustion on a treadmill according to Bruce protocol, the elderly runners presented a 52% higher VO2 max (maximum oxygen consumption) than the elderly sedentary subjects – showing similar results as the young sedentary subjects. High VO2 Max is an indicator of fitness and represents the amount of oxygen the body can utilize in one minute at maximum capacity.
It was determined in advance that the cytokine profile would be an accurate way to measure immune system health, so blood was tested using careful protocol. Cytokines are proteins released by cells and include interleukins (IL) which generate an immune response when necessary. A high level of serum IL-2 is known to be associated with healthier immune system response and was found to be at a much higher level in elderly runners than their peers – at a similar level to that of the young men. Low levels of serum IL-6 were found in the elderly runners as compared to their peers. Low levels of this serum have been hypothesized to be a marker of health in aging. IL-3 in the elderly runners was found to be at a similar level to that of the young men, suggesting that training over a long period of time may counteract the effects of aging on this interleukin. All other blood levels tested did not show any significant difference from their elderly peers. Hormones in this age group did not seem to be affected by exercise.
As humans age, exercise capacity and heart rate variability (HRV) decline. The effect is a lowered ability to carry out strenuous tasks, and a higher rate of heart issues and possibly earlier death. Researchers in
20 healthy male veteran runners with an average age of 68.5 (+-4 years) were studied and compared to 20 healthy sedentary men of the same age. The runners had been practicing endurance running for at least 40 years, training 1-2 hours for 5 days each week, including long distance 3 days and walk-weight training for 2 days. They also raced 5-10k each week or 20 k every 2 weeks. The athletes with higher than 55 VO2 max and sedentary individuals with lower than 45 VO2 max were selected. This parameter may have affected the results.
HRV was examined using 24 hour Holier monitoring and then analyzed by computer. Exercise capacity was measured using a ramptype progressive exercise test on a cycle ergometer to the tolerance limit. The ergometer was equipped with a computer which regulated exercise intensity while they maintained a cadence of 60 revolutions per minute after warm-up.
The two groups were similar in Body Mass Index (BMI), total cholesterol and glucose values, but the athletes showed lower blood pressure and resting heart rate, increased HDL (the healthy form of cholesterol) and decreased LDL cholesterol (the unhealthy form of cholesterol). HRV measures were significantly higher in the athletes compared to the sedentary controls.
Comparisons between Athletes and Former Athletes (Nessel, 2004)
Normal losses in VO2 max in non exercisers run an average of 1% per year in normally active men after age 35, showing a reduced ability for the body to use oxygen during aerobic activity. According to a review of literature (Nessel, 2004), one study showed that runners who stopped training during middle age actually had a loss of 43% from the ages of 23-53 while another study showed runners and rowers who had continued training at a high level experienced only a 5-6% decline per decade (and sometimes as low as 1-2% per decade).
He also reports that “endurance training decreases the loss of elasticity from the lungs and chest wall,” so he believes losses in VO2 max are caused by slowed transport of oxygen to muscles rather than decreased respiratory ability. “It appears that high intensity training has a slowing effect on the rate of loss in aerobic capacity during the early and middle years of adult life (30-50 years of age), but less effect after age 50” (Nessel, 2004). However, Nessel also notes that cardiovascular improvements resulting from training for the older individual are similar to those obtained by a younger person.
So the typical question remains: is running healthy for athletes’ joints? Many runners quit because of fear of osteoarthritis (OA) in the lower extremities, and those who do not quit, are often chastised by friends and relatives. Though research is still needed on this subject, the consensus seems to be that high impact, repetitive sports do result in injury, which seems to be a high risk factor in developing OA, but that running in itself does not present a problem for this particular disease (Conaghan, 2002). In fact, according to Runners World, a 14 year longitudinal study compared runners who ran an average of 26 miles per week to those who ran 2 miles per week. The runners were found to have “25% less musculoskeletal pain” than the controls (Burfoot, 2006). The hypothesized reasons for reduced pain are increased stability and strength of the muscles and tissues surrounding the joints of a well trained athlete.
Another possible factor in joint health may be attributable to a reduction in excess body fat in seasoned runners. In an article in Runners World, Ketteler (2007) reports that “sedentary, overweight people are 45% more likely to develop OA than those who are active”. She interviews Dr. Patience White, M.D., of the Arthritis Foundation, who believes excess weight produces pressure on the joints and “seems to accelerate the breakdown of cartilage”. Older endurance athletes (age 45) have a reported average body fat of 11% for men and 18% for women compared to sedentary averages of 19% and 26% (Nessel, 2004).
VO2max gains through exercise while young are obviously not retained when training ceases. At the same time, losses that are inevitable with aging are kept minimal only through continuous, vigorous training. There appears to be no need to cut back on training intensity as long as one is medically able, and as long as one “listens to the body” when there may be risk of joint injury leading to increased risk of OA. In fact, cutting back will result in losing all that one has gained through sometimes years of training. Continuing at a comfortably high intensity will considerably reduce the losses to cardiovascular and immune system health.
Though it is impossible to prevent the inevitable when it comes to aging, it is certainly possible to maintain a high quality of life and increased life expectancy. Running, as well as other endurance training appears to be a viable and low risk way to accomplish this, in tandem with proper diet and strength training. When taking all the benefits of running into consideration and weighing them with any possible risks, it is difficult not to conclude that continuing to run at a high level would allow one to expect the longest, healthiest, most pain-free life genetically possible.
References:
Anderson, O. (1998, August). Defeat father time. Runner’s World, 33(8), 34. Retrieved March 21, 2008, from Research Library database. (Document ID: 31701520).
Arai, M. H.,
Burfoot, A. (Feb 2006). Does running cause arthritis?. Runner’s World, 41, 2. p.55. Retrieved May 14, 2008, from Health Reference Center Academic via Gale: http://0-find.galegroup.com.alice.dvc.edu:80/itx/start.do?prodId=HRCA
Conaghan, P G (2002). Update on osteoarthritis part 1: Current concepts and the relation to exercise. British Journal of Sports Medicine, 36(5), 330-3. Retrieved May 14, 2008, from ProQuest Health and Medical Complete database. (Document ID: 222988831).
Galetta, F., et al. (2005). Lifelong physical training prevents the age-related impairment of heart rate variability and exercise capacity in elderly people. Journal of Sports Medicine and Physical Fitness, 45(2), 217-21. Retrieved March 21, 2008, from ProQuest Health and Medical Complete database. (Document ID: 920579341).
Ketteler, J. (10/25/07). The benefits of running. Runner’s World. Retrieved May 14, 2008, from Runners World website http://www.runnersworld.com/article/0,7120,s6-241-285–12232-0,00.html.
Nessel, E H (Summer 2004). The physiology of aging as it relates to sports. AMAA Journal, 17, 2. p.12(6). Retrieved March 21, 2008, from Expanded Academic ASAP via Gale.
Copyright Susan Puetz Turnquist, NASM-CPT, AFAA-CGT, 2008
