How Much Exercise Do You Need?

In the most recent issue of the British medical journal, The Lancet, a study of over 400,000 people in Taiwan followed for an average of eight years has shown that you don’t need to exercise a lot in order to reap the benefits — including a longer life. As little as 15 minutes of exercise a day or 90 minutes a week can add up to 3 years to your life! Men in the study lived on average 2.55 years longer than their non-exercising counterparts and for women, there was 3.10 years on average between the active and the sedentary group. This translates to a decrease in overall risk of dying by 14% with as little as 15 minutes of exercise a day with a further reduction of 4% for every additional 15 min of daily exercise beyond the minimum amount of 15 min a day.

What type of exercise and what level of intensity?

Researchers examined different types of exercise from regular walking to fast walking to jogging to running and found the benefits were there at all levels but they did confirm that there is a dose-response relationship, so that those who exercised for longer periods and at a higher intensity level reaped more benefits. Again, the participants in the study were compared with people who did no exercise at all. What this study shows is that there are benefits at even 90 minutes a week (6 days X 15 minutes), which is less than Canada’s new guidelines of 150 minutes a week at a moderate level or above. However, the study also showed that those who met the generally recommended guidelines of 30 minutes per day at a moderate level, life expectancy was even greater (4.21 years longer for men, on average, and 3.67 years longer for women).

To your health,

Chris

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”.

Controlling Diabetes Through Exercise

Spoonful of SugarLast week a lead article in the Toronto Star appeared with the headline “New diabetes ‘epidemic’”. The newspaper used such strong language because 2 million Canadians already have Type II Diabetes, another 600,000 may not even know they have it and 3 million may have the disease by the end of this decade.

What led us to this epidemic? Before answering that, let’s look at the disease a little more closely.

What is Diabetes?
Diabetes is a disorder that prevents blood sugar (glucose) from being properly used by your body for energy. Your body produces a hormone called insulin that lets you make use of the glucose you get from the food you eat. Insulin is produced in an organ called the pancreas.

There are three types of diabetes:

  • Type I, often called “juvenile diabetes” is a condition where the pancreas does not produce enough insulin. It accounts for about 10% of all diabetes cases. This condition appears before the age of 30 and its cause is genetic.
  • Type II, often called “adult-onset diabetes”, is a condition which develops when your body becomes resistant to its own insulin. Even if you produce as much insulin as a non-diabetic, your body needs more to get the same effect.
  • A third type, gestational diabetes, affects 3.5% of non-aboriginal women but up to 18% of aboriginal women and occurs during pregnancy. Its diagnosis and treatment is the same as for Type II diabetes. Gestational and Type II diabetes together make up 90% of diabetes cases.

There is no cure for Type I diabetes. People with this condition control it through insulin injections. Type II diabetes is a different story: it is controlled by changes to diet and lifestyle, and sometimes with drugs. And unlike Type I diabetes, Type II is largely preventable.

Why is it serious?
Diabetes is difficult to treat once it develops. It is the leading cause of blindness, kidney failure and limb amputations. As well, it can lead to coronary heart disease, strokes, blood vessel and nerve damage, and infections such as gangrene.

Some important facts about Type II diabetes:

  • It is one of the leading causes of death among Canadians.
  • Diabetics are 15 times more likely to require lower-limb amputation than the general population
  • 25-45% of men with diabetes have erectile dysfunction
  • Type II diabetes is six times more common in adults over age 45 than those ages 30-44 and is very common in adults over age 65.

What Causes Type II Diabetes?
The short answer is glucose intolerance. This means that when you eat, your body doesn’t produce enough insulin to process the food energy, so your blood sugar level goes too high. We don’t know whether aging itself plays a role in glucose intolerance or if other changes we relate to aging do: like increased body fat, decreased muscle mass and decreased physical activity. It is now believed that a lifestyle of overeating and physical inactivity has made the biggest contribution to the increase in Type II diabetes. And physical inactivity is as strong a risk factor in complicating the disease as cigarette smoking, high blood pressure and high cholesterol.

Some good news:
We now know that exercise and diet changes can go a long way to controlling the disease. Regular exercise can help reverse the decreased insulin sensitivity we often see in older people.

How Exercise Helps
Improving your muscular strength through resistance training and cardio-respiratory endurance through aerobic exercise will help you control your diabetes. Besides maintaining and improving bone mass, resistance training will help you reduce body fat, reduce blood pressure, improve blood lipid levels, and control blood glucose (see sidebar #1). Regular aerobic exercise can also be helpful in controlling coronary heart disease and help reduce your body fat. Besides aerobic activity and resistance training, your exercise program should include flexibility and balance training.

Risks of Exercise:
Although exercise is encouraged for diabetics, it does come with some of its own risks. The most common is hypoglycemia (low blood sugar). This is more likely to occur in individuals who are taking diabetes medication, because the added demand for glucose (caused by exercising) may not have been accounted for in your dosage and diet regimen. Be sure to see your doctor before beginning any exercise routine (see sidebar #3) and be sure to tell your fitness instructor or personal trainer if you are diabetic or hypoglycemic (see sidebar #2).

Another risk factor of exercise is the chance of foot injury, which could lead to an infection from a condition called peripheral neuropathy. This is caused by damage to the small blood vessels and nerves in your hands and feet. This can mask injuries because of you may not have any of the clues your rely on, such as pain, when you stub your toe. Watch where you are walking! (see sidebar #2)

What You Should Do
The Canadian Diabetes Association recommends several things to help you manage your disease, including:

  • Screening – for high blood pressure, high glucose, and high cholesterol
  • Improving Your Diet – by eating a balanced diet high in fibre and low in fat. Be sure to include plenty of whole grains, fruits and vegetables, and get your protein from vegetable sources, fish, and lean meat. More information can be found in Canada’s Food Guide. You may want to talk to a registered dietician for help with managing your food intake and food selection. More information can be found at www.dieticians.ca
  • Increasing Physical Activity – Build physical activity into your day, every day. More information on becoming more active can be found in Canada’s Physical Activity Guide for Older Adults.

Remember…
Along with changes in diet and lifestyle, regular exercise can help control diabetes! It will help you lose weight, because as you become more active, you will burn more calories. And as we have seen, it will also help control your blood glucose levels.

If you are new to exercise or have a hard time staying motivated, look for exercise programs in your community that are enjoyable. You may want to talk to a personal trainer or fitness consultant to begin a home exercise program or for assistance if you join a gym.

To your health,
Chris

References

Barnes, D.E. (2004). Action Plan for Diabetes. Champaign, IL: Human Kinetics

Goulet, E.D. et al (2005). No sustained effect of aerobic or resistance training on insulin sensitivity in nonobese, healthy older women. Journal of Aging and Physical Activity, 13, 314-326.

Kriska, A. (2000). Physical activity and the prevention of Type 2 Diabetes Mellitus: how much for how long? Sports Medicine, 29(3), 147-151.

New diabetes ‘epidemic’. Toronto Star, September 21, 2005

Ryan, A.S. (2000). Insulin resistance with aging. Sports Medicine, 30, 327-346.

Westcott, W.L. & Baechle, T.R. (1999). Strength Training for Seniors. Champaign, IL: Human Kinetics