The Ageing Process - PartIII

In part III on the ageing process I’m going to cover in brief, several topics ranging from strength and functional capacity to protein needs, metabolism and neural functioning.

Strength and Functional Capacity

There is a significant correlation between muscular strength and preferred walking speed (aerobic power) for both male and female. Leg power is considered a useful predictor of functional capacity in older populations (and even in some younger populations). Muscle strength in older populations is therefore a critical component of walking ability. This is usually the first sign (apart from eyesight) that age is kicking in and hence the reason we should be taking notice and taking positive steps to address the situation sooner rather than later with strength training.

Age Related Changes in Muscle Morphology

Firstly, fibre type. We all have two types of muscle fibre commonly referred to as fast twitch (type II + IIa) and slow twitch (type I). A strong body of evidence has pointed to a shift to a more homogenous “mix” of muscle fibre due to a conversion between type II and type I muscle fibres or from a preferential loss of type II muscle fibres. In other words our fast twitch fibres become less due to our “slowing” down with age, and they become slow twitch fibres. This is more the case with our type IIa fast twitch fibres as they have the ability to be type I or II.

Secondly, fibre size and number. The most reported effect of ageing has been related to age-related muscle atrophy (loss of lean muscle mass), using measures of total body nitrogen, total body potassium and urinary excretion of creatine. Old muscle that has atrophied is likely to be at greater risk of muscle fatigue when performing daily tasks, compared to non-atrophied senile muscle. Loss of functional capacity follows muscle fibre loss and changes in fibre type.

Loss of Neural Functioning

Weakened muscular contractions may lead to a lack of appropriate feedback to the nervous system, leading to further neural degradation and further impairment of muscle in terms of weaker contractions. Weaker muscle in the upper and lower leg further increases the risks of falls, and a decline in muscular strength may also potentiate the loss of bone mineral in seniors.

Trainability of Muscle With Age

Most studies support the view that if the intensity and duration of aerobic training is adequate, elderly skeletal muscle can adapt in a similar way to that of young muscle.  Mitochondria (sausage-shaped organelles) density and oxidative enzymes can be increased in older populations, as can capillary density. (Mitochondria are the cell’s power producers. They convert energy into forms that are usable by the cell).

Selective hypertrophy of type I muscle fibres have resulted from continued aerobic training. While strength training can modify the age-related changes in muscle morphology and function, aerobic training such as swimming can increase tensile strength of elderly tendons.

Protein Needs and Ageing

Inadequate dietary protein may be associated with sarcopaenia (loss of muscle mass). The response to long-term decrease in dietary protein is loss of lean body mass. Safe protein intake recommended for elderly adults is 1.00 to 1.25 grams per kg.

Energy Metabolism in Older Adults

Daily energy expenditure declines throughout adult life. Fat-free mass (FFM) is the main determinant of energy expenditure in sedentary individuals. Preservation of FFM will therefore help prevent the decrease in metabolic rate and hence control your body fat levels.

Cardiovascular/Blood Pressure/Body Composition

Older adults receive the same 10-30% increase in VO2 max with prolonged aerobic exercise as well as improved glucose tolerance and insulin sensitivity. Light to moderate endurance exercise appears to lower blood pressure to the same degree in younger and older adults. Body composition is also improved in a similar fashion to younger adults. The most consistent change is a 1-4% reduction in overall percent in body fat with aerobic exercise in older adults, even if body weight is maintained. Visceral fat (the fat stored around your organs) has been shown to decrease by 25% in older men who lost only 2.5kg of body weight with aerobic exercise.

When it comes down to it, the choice is still yours alone as to how you want your health and fitness to pan out as you age. Retirement is on everyone’s mind and the plans for retirement are many and varied. If you chose right you will be able to spend your retirement doing what you planned to do, or spend it on medication and doctors visits trying to fix yourself.

“As much money and life as you could want! The two things most human beings would choose above all – the trouble is, humans do have a knack of choosing precisely those things that are worst for them.” – J.K.Rowling

Remember it’s never to late to “Change-Challenge-Achieve.”

 

Martin McKone