Humans_Concept_2

Subject Facts

Automatic' movements

Many of the movements that we take for granted are anything but automatic when we learn them. After spending a considerable portion of your life (well, it probably seems so at the time) desperately pulling yourself to a standing position, you soon get the hang of the balancing and walking around' idea. But actually observing what you do, examining each small movement in detail helps you to realise what a difficult thing it must have been to begin with. The central nervous system stores up these habitual movements as subroutines: embedded, semi-automatic functions.

The concentration and coordination needed to direct a spoonful of food successfully into the mouth is initially great By the age of eight or nine, children are capable not only of feeding themselves, but also of balancing on one leg of their chair and watching TV at the same time! However, I have also noticed that there are times when — rather in the way that a computer 'locks up' if you run too many programs at the same time — my children 'lock up' with food halfway to their mouths whenever there's a particularly exciting piece of TV that requires their full attention, What amuses me most is when the fork finally reaches the mouth, the 'automatic' chewing action begins and a frown spreads across the face, denoting 'there's something wrong here', as they realise that the food has dropped off somewhere between plate and mouth.

The key point here is that actions become more precise and fess conscious with practice, Sports coaches often say things like 'It's important not too think too hard about it' or 'Don't think about hitting the ball, just hit it'. This is because if we focus on every little movement we take as part of a bigger action, the brain will tend to get in the way. The subroutines or automatic systems need to be allowed to do their job. Generally the more we practise, the more embedded an activity becomes, and the better (or faster) it can be performed.

Fitness

With repetition of particular movements there is not only an increase in the level of skill, but also an increase in the level of fitness — that is, the combination of strength, suppleness and endurance (see illustration). Muscles only develop when the are used: if you do not perform particular movements for a long period of time (for example, if you tie in bed for a number of weeks), the unused muscles will deteriorate. Where an activity is repeated, however, there will be muscle formation to support that movement. The type of muscle formed may allow the movement to be performed more quickly, more strongly or for longer (or a combination of the three). The muscles used will also recover more quickly from their exertion. In this way, we adjust to become 'fitter'. To ensure all-round fitness, we need a pattern of exercise that develops the full range of muscle groups.

Energy delivery

The key to overall fitness is the heart. This delivers oxygenated blood to the muscles, enabling them to convert energy into movement. To get the blood to the muscles when it is needed, the heart needs to pump faster and/or pump a greater volume of blood. Sustained exercise, involving exertion for twenty minutes at a time, can make the heart stronger so that it will beat faster and more powerfully. By increasing the amount of oxygenated blood being delivered to the muscles, the period for which the muscles can respire aerobically can be increased,

If the muscles are not able to convert energy fast enough aerobically, they will begin anaerobic respiration. This will result in a build-up of lactic acid in the muscles, causing the 'tired' feeling, When the activity ends, the need to remove the accumulated lactic acid will cause a continued need for oxygen (panting) and increased blood flow (elevated heart rate) until the muscles return to normal. The less fit you are, or the less efficient your heart is at delivering oxygenated blood, the sooner you will move into anaerobic respiration and the longer it will take to recover from it.

The measurable effects of sustained exercise are that the heart can beat faster under strain, it can return to the 'at rest' rate sooner, and the ^fat rest' rate itself is slower (the heart doesn't need to beat as often to pump the same amount of blood). As you progress into an exercise regime, it is possible to chart your improved cardiovascular (heart and circulatory) fitness by measuring these three indicators.

Flexibility

Suppleness — the ability to stretch and move to the extremes that our joints will allow without being injured — is also a benefit of exercise. The stretching of muscles in a 'warm-up' prior to vigorous exercise is particularly important if muscle damage is to be avoided Progressively and gently stretching the muscles causes their fibres to 'warm up' (their metabolic rate is increased), allowing them to increase their uptake of oxygen from the bloodstream. This preparation helps to prevent the muscles from becoming overstrained when they are put under pressure during activity. This is as true for the heart as for any other muscle.

As well as increasing the bulk of muscles, repetitive exercise can also increase their length. Muscles and tendons attach one bone to another across a joint. If they are not regularly stretched, both will gradually shorten to restrict movement around the joint. Regular; gentle stretching exercises will increase suppleness, ensuring freedom of movement and mobility of the joints.

Exercise and diet

Exercise and diet work together to ensure that the energy consumed is equal to the energy used. The more exercise is carried out, the more energy-giving food is required — but as soon as the level of exercise is reduced, there must be a corresponding decrease in food intake if an increase in body weight is to be avoided. When we are trying to develop general fitness, strength and suppleness, we need to increase our intake of growth foods (proteins) in order to build more body tissue where required.

A further nutritional requirement of increased activity is an increase in the level of water intake. This directly increases blood plasma levels, improving the transportation of nutrients around the body and helping to filter out the waste by-products of physical activity (heat and urea). Sipping small amounts of water frequently is the best way of maintaining a balanced fluid level.

Teaching ideas

It is important not to over-stress the children or require them to perform activities that are currently beyond their abilities. Differences in physical ability between the children need to be treated with sensitivity

How to walk (sequencing, recording)

Walking might seem easy — but could the children tell a robot how to walk? Let them work in pairs, giving and following instructions, then writing down an agreed set. Can they give instructions for other movements?

Movement and muscles (observing)

Encourage the children to be aware of all the coordinated movements that are necessary to pick up a pencil, or to stand up and sit down. Performing these actions in slow motion will increase their motor control and allow them to focus on different aspects. Which particular muscles are involved? How are these muscles controlled?

Stretchy legs (comparing, recording)

This activity can be linked to PE. Ask the children to sit on the floor with their legs stretched out in a VI then to walk their hands forward, bending at the waist until the backs of their legs feel tight — they can stop there! Measure how far they have reached forward, Repeat this every day for a few weeks: are they able to reach further by the end? Are some children more supple than others?

Heart rate (measuring, recording)

The children can find and record their pulse rates by measuring the number of wrist pulses (see illustration) in 1 5 seconds, then multiplying by four. Encourage them to participate in some fairy vigorous aerobic activity. They should record their pulse rate for the first 1 5 seconds after stopping, then for 15 seconds in every minute for the next five minutes. What is their peak pulse rate? How soon do they return to the 'at rest' rate? Within a PE programme, this activity may be repeated over a period of six weeks or more to help the children chart their fitness development.

Aerobic exercises (planning, researching)

Groups of children can research different forms of aerobic exercise (using encyclopaedias, textbooks or the internet) and plan an exercise routine, working on a range of different areas of the body with full warm-up and cool-down sections.

Compare the groups' results. Are there any similarities between their programmes? Are some elements or body areas common to all the programmes (for example, an increased heart rate)? Is there a difference between the 'fitness' elements and the Strength' elements?