– an investigation into the positive health benefits of regular exercise

Exercise plays an important role in all the phases of life, not just until you pass your driving test! Ian Craig gives some good reasons to get moving, and suggests some exercise options.

Not all that far back in the evolution of humankind, exercise was something we did in order to survive. In palaeolithic times hunter-gatherers walked long distances every day in search of edible plants and small animals. At the same time they needed to be in a state of constant readiness to escape from danger – for the burst of energy involved in ‘fight or flight’. Much more recently agriculture was still extremely labour-intensive and a large part of the population worked on farms and in fields.

When I lived in London I was personal trainer to a Scottish couple in their fifties. Their son was getting married, and his grandmother was coming to the wedding from the city of Glasgow and his grandfather from the Outer Hebridean islands. At the wedding the rather bad-tempered grandmother was pushed around in her wheelchair, and obviously preferred complaining about life to socially interacting. The grandfather, who was still working as a shepherd, enjoyed the wedding immensely and danced the young ladies off their feet! This was a potent reminder of the health and psychological benefits of a rural lifestyle.

Unfortunately with the advent of motorized equipment there has been a huge shift in the way we lead our lives, to the extent that the majority of the population is now office-based. As a species we were designed to move, and we haven’t yet evolved to a stage at which we can be thoroughly healthy and sedentary at the same time.

If you aren’t yet convinced of the benefits of exercise, here are some modern scientific views on the subject.

CARDIOVASCULAR HEALTH

Cardiovascular (CV) exercise has been shown to increase maximum aerobic capacity beyond what is considered ‘normal’ for specific age groups.¹ Combined with an increase in heart chamber size and peripheral vascularisation and oxygenation, this will certainly make active life more enjoyable and is thought to reduce risk factors associated with CV disease.² Regular exercise has been associated with an improved blood lipid profile (cholesterol and triglycerides), blood pressure and blood clotting activity. In addition, even if an obese individual doesn’t lose much weight with exercise, increased CV fitness reduces CV mortality compared with lean but unfit individuals.

ENDOCRINE BALANCE

Practitioners in many disciplines attempt to manipulate hormone levels in the body. An interesting book appeared recently, authored by the die-hard American personal trainer of the ‘The Biggest Loser’ TV programme, Jillian Michaels. In her book, Master Your Metabolism,³ she admits having had a ‘go-hard or go-home’ attitude to her clients in the past, but says that she is now focusing more on life balances that can stabilise hormone function. Exercise has the following effects on hormone levels:⁴

• An increase in growth hormone stimulates muscle growth, fat metabolism, retention of bone calcium and the immune system, and contributes to pancreatic health (for insulin control).
• Raised thyroid hormone levels (TSH, T4 and T3) increase metabolic rate and circulation, regulate long bone growth, and affect connective tissue flexibility and protein synthesis.
• Cortisol (the stress hormone) mobilizes fuel for energy, allowing us to perform daily activities and adapt to stresses. Relaxing activities such as a walk in the country, a ‘coffee-shop’ cycle ride and breathing based practices like yoga and tai chi tend to decrease stress hormones. A hard gym or sports training session is likely to elevate stress hormones. So a long, heavy bout of exercise is not always the healthy option it’s considered to be. Depending on other factors in the person’s life, they may or may not be able to manage this additional (or ‘accumulative’) stress.
• Insulin carries sugar in the blood to metabolically active tissues as an energy source. This is one of the most important health functions of exercise in this modern age of burgeoning waistlines, obesity and diabetes. Exercise actually sensitises tissues to the effects of insulin, meaning that sugar is more likely to be used for energy than stored on the belly or converted to blood lipids.

NEUROMUSCULAR HEALTH

Mice subjected to running, climbing and swimming during late postnatal development have been shown to have significantly higher brain weights and greater dendritic fields in the cerebellum than inactive controls. This is the part of the brain that plays an important role in sensory perception, co-ordination and motor control. In addition, 12 weeks of endurance or interval-based treadmill training significantly increased dopamine receptor binding in rats.⁵ The researchers suggested that endurance training may slow down the effects of age on dopamine receptor deterioration – the brain chemical dysfunction involved in Parkinson’s disease.

Strength training has been shown to increase muscular contraction (change to contractile strength) by 40 – 50%. This means that in the early stages of a resistance training programme your strength levels will increase without significant muscular growth. Perhaps this does not seem important to a sedentary person, but strength and stability may slow the onset of age-related musculoskeletal degeneration and eventual dependence on others. With this in mind, Westcott and colleagues⁶ put 19 non-ambulatory elderly patients (average age 88) through a 14-week resistance-machine training programme. At the end of the study the patients had reduced their body fat by an average of 9%, increased leg press strength by 81% and increased hip flexibility by 52%. Very importantly, their average mobility distance almost doubled, falls decreased by 36%, and medical staff found a marked increased in independence.

SUMMARY

You have seen a range of good reasons why an exercise programme can be beneficial to health. Exercise plays an important role through all phases of life, not just until the driving test has been passed.

• Allowing children the opportunity for free play as they grow can help with development of motor skills, insulin sensitisation, body composition, bone mineralisation, confidence and social interaction.
• For adults, a moderate exercise programme helps with healthy weight management, while reducing the likelihood of diabetes, CV disease, cancer and autoimmune conditions. Exercise has been shown to reduce symptoms of depression and anxiety and increase the ability to deal with life stresses.
• Although pregnancy is not the time to take up strenuous exercise, physical activity can reduce the risk of pre-eclampsia, gestational diabetes and lower back pain during pregnancy and improve mood, vigour and self-image afterwards.⁷
• In the elderly, exercise can increase independence into old age, reduce the chance of developing osteoporosis and increase psychological empowerment.

WHAT NEXT?

So, what kind of exercise is healthiest? All types of exercise have their place, although some appeal to certain individuals more than others. The American College of Sports Medicine recommends up to 3 – 5 hours of CV exercise a week for healthy body composition, although others suggest even more, to make a meaningful difference to body fat.

Resistance training, via its influence on anabolic hormones, is extremely effective in maintaining or increasing muscle mass, which supports a healthy body composition because muscle is more metabolically active than fat. Conversely, relaxation practices such as yoga and Tai Chi are anti-catabolic (muscle breakdown) and have a stabilizing effect on stress hormones and insulin, which in turn can positively influence body composition, as well as decreasing muscle tension, improving digestive function and supporting mood.

Some suggested exercise options are listed in the accompanying box. For a well-rounded exercise approach, you might consider 3 – 5 bouts of CV exercise per week, of varying intensity and duration, 1 – 3 resistance sessions and 1 – 3 periods of relaxing movements. The exact form your exercise pattern takes will depend on your personal preferences and your time commitments, but the basic aim is to express yourself through movement most days of the week.

Cardiovascular

Walking, running, cycling, swimming, aerobics, aqua-aerobics, tennis, squash, soccer, etc. (anything that uses big muscle groups in a repetitive way)

Strength

Weight training, Pilates, movement with exercise balls and bands

Relaxation

Yoga, tai chi, Pilates, anything that involves focus on breathing

References

1. Hollman W, et al. The cardiovascular system. In Dirix A, et al., eds. Olympic Book of Sports Medicine. Oxford: Blackwell Scientific Publications, 1988: 40-48.
2. Myers J. Exercise and cardiovascular health. Circulation 2003; 107: e2-e5.
3. Michaels J. Master Your Metabolism. New York: Crown Publishers, 2009.
4. Powers S, Howley ET. Hormonal responses to exercise. In: Exercise Physiology. Dubuque, Iowa: Wm. C Brown Publishers, 1990: 69-116.
5. Gilliam PE, et al. The effects of exercise training on [3H]- spiperone binding in rat striatum. Pharmacol Biochem Behav 1984; 20(6): 863-867.
6. Westcott W, et al. Strength training elderly nursing home patients. Journal of the American Senior Fitness Association 2000; 1-www.seniorfitness.net
7. American College of Sports Medicine. Impact of physical activity during pregnancy and postpartum on chronic disease risk. Med Sci Sports Exerc 2006; 38(5): 989-1006.