Foot Sensitivity and Balance

(CBC Radio One Quirks and Quarks)

CBC Radio Host Bob McDonald interviewed researcher Dr. Leah Bent at the University of Guelph who measured skin sensitivity of astronauts before they visited the International Space Station. She will follow this up when they return. She is interested in how skin on the soles of feet and vestibular (inner ear) input relate to balance in seniors. Much research has been done on the effects on balance in older adults due to changes in what is believed to be the three components of balance: visual, vestibular, and proprioception. Proprioception is the body’s ability to sense where it is in relation to the environment through skin sensitivity, foot and ankle placement, and stability. Studies have shown that these three components are all compromised with age and thus older adults have a higher risk of falling. Dr. Bent’s research is concerned with pin-pointing which receptors in the feet are most affected by periods of weightlessness such as when astronauts are in flight. It is believed that since astronauts in flight have compromised vestibular input because of loss of gravity, skin sensitivity is increased, allowing them to maintain balance. It is Dr. Bent’s hope that by better identifying these skin receptors, she will be able to target them specifically to improve their sensitivity in seniors, thus decreasing the risk of falling. Exercise regimens which are used to improve balance in older adults tend to be quite generalized, by increasing muscular strength in the ankle and hip and enhancing the proprioception by shutting down or compromising the other two components, for example doing one legged stands with eyes closed (visual) or doing tandem walking while turning the head (vestibular). Instead, if specific proprioceptors in the feet can be identified and thus stimulated in further experiments, this may be a more effective way to balance-train older adults.

Speed of Behaviour in Older Adult Drivers

( from “Effect of Exercise on Speed of Behaviour in Older Drivers”, Journal of Aging and Physical Activity, 19.1, 48-61 (January 2011) ).

Researchers at the University of Évora in Portugal studied the effects of an exercise program on the speed of behaviour of older adults while driving. Speed of behaviour encompasses reaction time (RT) to environmental stimuli and speed of execution of a task. Speed of behaviour is known to decrease as we age and in driving, this can be especially detrimental for obvious reasons. Twenty-six community dwelling drivers aged between 55 and 78 were assigned to either a control (non-exercise group) or the study group who exercised for 1 hour, 3 times a week for 8 weeks. Baseline tests were performed to measure brake RT, peripheral RT (detecting a light beaming into the windshield at the side), choice RT (choosing between two external stimuli such as braking and detecting an outside light stimulus), and a dual task RT (where participants had to apply the brake while performing a mental calculation at the same time). The exercise intervention consisted of a program with a number of eternal stimuli being given which required a fast reaction while continuing to walk and other physical activities such as stepping, reaching, throwing, etc. Thus there was a physical as well as a cognitive element to the program. After 8 weeks during re-test, improvement to speed of behaviour was significant in all measures for the exercise group. For the control group, not only was there no improvement, but there was decline in speed in all but one measure. Thus the researchers concluded that older drivers’ speed of behaviour can be improved through exercise and that exercise programs should include activities that stimulate cognitive and perceptive abilities.

Muscle Mass and Middle Age

(“Canadian Health” (Winter 2011).

Dr. Greg Wells, a Toronto-based sports scientist was recently interviewed in Canadian Health magazine on his views of the importance of lean muscle mass through weight training in improving the health of middle aged men. Some of the benefits he cited were:

  • Increase in metabolic rate allowing you to burn more calories and thus reduce risk of obesity, cardiovascular disease and diabetes. Fat is inert but muscle is active even at rest so calories have to be burned just to keep that muscle alive.
  • Protection of joints by stabilizing them, thus relieving them of having to do all the work when carrying loads. Stronger joints will also reduce risk of osteoarthritis, falls and fractures that can increase with age. Muscle mass itself provides a protective layer to the bones if you do fall, lessening the chance or severity of fractures.
  • Look and feel better by reducing flab and wasting appearance of aging. Says Dr. Wells: “Exercise is proven to prevent almost every chronic disease. If you want to be healthy and fit over your whole life, a combination of strength, cardio and flexibility is the ticket.”
  • Increased stamina and can potentially give you a better sex life. “At least you’ll be less likely to fall asleep from exhaustion afterwards”, says Wells.

Can Exercise Keep You Young?

(from the New York Times, March 2, 2011)

Researchers at McMaster University in Hamilton, ON are attempting to answer the question, “Can Exercise Keep You Young?” Dr. Mark Tarnopolsky was surprised when he and his students discovered that exercise kept a strain of mice from becoming grey prematurely. They studied mice whose cell mitochondria were altered to lack the inherent repair mechanism so that they aged prematurely. Things like muscle shrinkage, decrease in brain volume, fur loss and greying, enlarged hearts, frailty, and even shrivelling gonads were all markers of an early aging process in the mice. However, they divided these genetically altered mice into two groups, a sedentary group and an exercising group. At 8 months (or about age 60 in human terms), the sedentary group showed the age-related markers and were all dead before they reached their 1st birthday. The exercising group on the other hand, remained youthful at 8 months. They maintained their dark fur, which was still full, their muscle mass had only shown a slight decrease as did their brain volume, their balance was good, and even their hearts were normal size as were their gonads. Even though they still had the genetic mutation that inhibited mitochondrial repair, they had more mitochondria and less damage than their sedentary cousins. All were still alive at age 1.

What was their key to the fountain of youth? A vigorous exercise regimen. They ran on a wheel for 45 minutes, 3X per day beginning at their 3rd month. This is the human equivalent of running a 50-55 minute 10K. Thus the exercise was of a cardio or aerobic nature and considered much more vigorous than what the general recommendations for exercise are. The researchers admitted that there is probably a threshold of exercise that needs to be reached in order to slow down physiological aging and this study was not meant to determine that threshold. Still, they believe that even following a less rigorous regimen humans can still reap some benefit. Besides prior studies has shown an improvement in mitochondrial function in older adults who did weight training at a moderate level. As Tarnopolsky has said, “Anything is better than nothing.” “If you havent been active in the past”, he continued, “start walking five minutes a day, then begin to increase your activity level”.