For many years it was thought that there was considerable deterioration in the various body tissues because of the aging process, however more recently, research is showing that the deterioration experienced is more due to disuse as opposed to the aging process itself. Here we outline some of the tissue changes that occur and how exercise can reduce the deterioration.
Tissue Changes in muscle
After the age of 60, there is a decrease in muscle strength and size. This reduction is predominately in the number of muscle fibres rather than the size. With regular training, the older person is able to markedly improve muscle strength and endurance. This is due to an increase in the size of the muscle fibres (there is no improvement in the number of fibres). The oxidative capacity (the muscles ability to use oxygen) of mitochondria in muscles, also markedly improves with regular endurance training in the older person. So, although there is a reduction in muscle strength and size with aging, this decline can be reduced and possible partially reversed with appropriate training.
Tissue Changes in bone mass
Bone mass declines slowly after your 30’s. There are a number of different factors affecting bone loss, however exercise forms an important part of preventative treatment. This is due to the increased load placed on the bone during weight bearing activities, e.g. running/ walking/ tennis/ stairclimbing etc, which stimulates bone growth. It is important to remember that the adaptations that occur in bones are site specific to the limbs being used, so it is important to include both upper and lower body weight bearing activities as well as including exercises which work the trunk muscles.
Changes in cardiovascular fitness
Aging affects one’s cardiac function as well as peripheral circulation. With aging, one’s stroke volume (the amount of blood pumped out of the heart per beat) falls significantly and the myocardial wall hypertrophies. These result in a reduced cardiac output. However regular exercise has been shown to improve stroke volume. This can be attributed to the fact that exercise tends to lower ones resting heart rate. A lower resting heart rate results in increased diastolic time (When the heart is in a period of relaxation and dilation) which allows for improved coronary flow. This in turn results in an increase in stroke volume. With aging there is also a decrease in elasticity of the blood vessels, however, the lower resting heart rate (associated with regular exercise) is associated with better elasticity in the arterial walls.
Tissue Changes in the nervous system
Aging does result in a slowed reaction time, which often means that they are less able to react to stimuli which may result in a fall. Once again, embarking on a structured exercise program including strength and balance training can help to reduce this risk. Next month we will discuss falls and exercises for fall prevention in more detail.
Changes in metabolism and body composition
One’s basal metabolic rate, VO2max and glucose tolerance all decrease with age, while one’s relative body fat increases with the reduction in lean muscle mass. Regular exercise helps to increase one’s lean muscle mass and assist in weight loss (along with a healthy eating plan). We mentioned earlier how exercise helps with glucose control and the increases mitochondria in the muscles also improve metabolism.
It is easy to see why making exercise a priority will be hugely beneficial to you, not only when you are young but even more so as we age to help reduce the negative effect of aging. For assistance finding the right exercises to suite you, consult with your nearest Biokineticist or contact us at Fish and Field Biokineticists to get you started on a suitable exercise program or to join one of our group aquatic therapy classes.
Peter Brukner and Karim Khan, (2001) Clinical Sports Medicine, 2nd edition, McGraw-Hill
Herbert A. DeVries, Terry Housch, (1994) Physiology of Exercise for physical education, athletics and exercise science, 5th edition, WCB McGraw-Hill
ACSM’s Guldines for exercise testing and prescription, (2000) 6th edition, Lippincott Williams and Wilkins