Through the Life Span

CHAPTER TEN Exercise Through the Life Span



Exercise and children 138

Physiological differences and responses to exercise in children 138

The effects of exercise training in children 139

Benefits of exercise in children 140

Special considerations when exercising children 141

Recommended exercise prescription 141

Exercise and pregnancy 141

Physiological differences and responses to exercise during pregnancy 142

Benefits of exercise during pregnancy 142

Special considerations when exercising during pregnancy 142

Recommended exercise prescription 143

Exercise and older people 144

Physiological differences and responses to exercise in older people 144

The benefits of exercise training in older adults 146

Special considerations for exercise in older adults 147

Recommended exercise prescription for older adults 149

Previous chapters of this book have discussed exercise guidelines and prescription for adults. This chapter considers how exercise should be tailored for the specific life stages of childhood, pregnancy and older age. Physiotherapists need to have an understanding of exercise in relation to life stage for three main reasons:


image to understand the normal activity levels of children, pregnant women and older people

image to understand how to safely treat children, pregnant women and older people with an exercise programme

image to understand how children, pregnant women and older people may respond to treatment with an exercise programme.


EXERCISE AND CHILDREN


Healthy children are usually active by nature; some activities are aerobic but many others are short-term bouts of intense activity interspersed with short periods of rest. Children’s physiology is different from that of adults and children respond to exercise differently from adults. As children develop at different rates, it is important to consider each child as an individual. There are several factors which will determine an individual child’s response to exercise. These factors include the chronological age of the child, the size of the child in relation to this and their stage of biological and sexual maturation.



PHYSIOLOGICAL DIFFERENCES AND RESPONSES TO EXERCISE IN CHILDREN


This section considers some of the physiological differences and responses to exercise in children compared with adults.



Differences in the ventilatory system


Many markers of ventilatory capacity such as FEV1 and vital capacity are related to the size of the child. There is little difference in these values between the sexes before puberty although some studies have shown a small increase in these values in favour of boys when comparing boys with girls. Small children have to work harder to breathe for each litre of oxygen consumed compared with adults so this means that they may not be able to sustain long periods of activity. As the child grows, breathing rate at rest falls and maximal breathing rate progressively declines. Resting tidal volume increases with age but also declines slowly relative to body size. Maximal exercise ventilation increases in proportion to height as the child gets older and their ability to sustain activity increases.



Differences in the cardiovascular system


Ventricular size and stroke volume increase in relation to the size of the child. Young children have a small heart and so have a higher heart rate and a comparatively small stroke volume. At maximal and sub-maximal exercise levels cardiac output is lower in children than in adults. To compensate for this the arteriovenous oxygen difference in children is larger so that the required amount of oxygen can reach exercising muscles during aerobic work. As the sinus node matures, resting heart rate falls in children. Myocardial contractility remains fairly constant between adults and children. Maximal changes in cardiac output parallel those of maximal oxygen uptake as the child grows. This again leads to an increased ability to sustain activity as the child grows.



Differences in oxygen uptake


Resting metabolic rate in children decreases relative to body size as children grow. Also as children grow, maximal oxygen uptake increases in relation to body size with little difference between the sexes in young children. As children go through puberty differences between boys and girls in maximal oxygen uptake of as much as 50% less in girls become apparent, particularly with boys in training. These differences between the sexes are related to body composition and size. Girls tend to be smaller and have more body fat than boys, and these differences persist into adulthood.



Differences in skeletal muscle


Muscle strength improves throughout childhood due to an increase in muscle size as the child grows and due to neural adaptation. At puberty, hormones play a large role in muscle development and result in much greater increases in lean body mass in boys than in girls.



Differences in other factors


Blood haemoglobin concentration and so the oxygen-carrying capacity of blood rises with age in boys more than in girls. Walking and running economy improve during childhood and so percentage of maximal oxygen uptake used at a given exercise intensity declines as the child gets older. Endurance performance improves as the child grows. Anaerobic performance also improves as the child grows – anaerobic power in children is smaller relative to size than that in adults.



THE EFFECTS OF EXERCISE TRAINING IN CHILDREN



Cardiovascular training


If an endurance programme is applied to young healthy children, any gains in maximal oxygen uptake will be less than those seen where an endurance training programme is applied to young adolescents or adults. The reasons for this are not clear and may be linked to the fact that children are usually active by nature so training programmes are not as effective or because of the hormonal changes which happen at puberty. Where children are hypoactive, for example those with chronic diseases, cardiovascular training may produce improvements in the child’s ability to carry out functional activities.



Resistance training


More recent evidence suggests that it is possible to increase the strength of muscles in pre-pubertal children with resistance training programmes. Muscle hypertrophy is not seen in these children to the same degree as that in an older child or adult following a resistance training programme, suggesting that neural adaptations are largely responsible for strength gains. Larger strength gains, which may have a positive effect on function, have been seen when resistance training programmes have been applied to hypoactive children.



BENEFITS OF EXERCISE IN CHILDREN


Children may benefit from exercise in many different ways depending upon their reason for doing the exercise.



Healthy children


As has already been stated, healthy children are usually active by nature, although in the last 10–15 years there has been increasing concern that children are becoming less active than they were previously. Children are often driven to school now when previously they may have walked or cycled. Many of the activities which children now enjoy such as playing computer games or watching the television may have replaced more active pastimes. This has prompted consideration of how being a less active child may track into adulthood in terms of developing conditions such as obesity, osteoporosis, coronary artery disease or hypertension. All of these diseases are linked to physical inactivity as a risk factor. A definitive study looking into this area has not been carried out but the available evidence supports the notion that a child’s activity pattern tracks into adulthood. If a child is very active, they are more likely to be active as an adult. The child’s parents have also been shown to be important in acting as a role-model in developing their child’s activity patterns. Children’s fitness has been studied over the last 50 years and there appears to be no trend in decreasing maximal oxygen uptake in children over this period. Neither does there appear to be a strong relationship between activity levels and fitness in children. However it is important to encourage children to be active so that they are more likely to maintain higher levels of activity as an adult.



Children participating in sport


More younger people are now participating in elite sport or regular training. Training of this type should be carefully monitored, particularly in terms of intensity to avoid injury.



Children with chronic conditions


For children who have a condition such as juvenile rheumatoid arthritis, cerebral palsy or cystic fibrosis it is ­important that exercise is encouraged in their daily life. Many of these children are hypoactive compared with healthy children of a similar age. They may also have to work at near maximal intensity to carry out simple functional tasks. Some evidence is starting to emerge which is showing the benefits of resistance training and fitness training on function in these children. This may be related to their ability to propel a wheelchair or in economy of function in terms of carrying out activities of daily living.



SPECIAL CONSIDERATIONS WHEN EXERCISING CHILDREN


To prescribe exercise safely for children the physiotherapist should be aware of the expected outcome of training for both cardiovascular fitness and resistance training.


Activities should be chosen that are easy and interesting for the child to carry out. Active play should be encouraged in younger children and older children may be involved in selecting activities which they would like to do and are possible for them to carry out. Special consideration should be given to the specificity of the activity or game being used in relation to the training programme.



RECOMMENDED EXERCISE PRESCRIPTION



Cardiovascular training


Current recommendations suggest that healthy children should do at least 60 minutes of moderate activity with some vigorous activity, which is intermittent in nature, on most days of the week.



Resistance training


Where resistance training programmes are applied to children, for example in specific conditions such as cystic fibrosis or for sports training, the following guidelines should apply:


image maximal (1 RM) or high-intensity programmes should not be used

image young children should not lift a heavier weight than 8 RM and up to 15 RM for each exercise, intensity being increased only when the child can easily perform the required number of repetitions in good form

image training should be carried out under supervision with focus on good technique

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Nov 7, 2016 | Posted by in MANUAL THERAPIST | Comments Off on Through the Life Span

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