Before We Start

Warm-up

Before starting an abdominal training session, it is vital to warm up. There are two main reasons for this: first, warming up can make sports injuries less likely in certain circumstances, and this is especially true for the spine; second, the body works more efficiently when warm and body functions may actually improve. A good warm-up will have effects in three key areas: physiological (body processes), mechanical (physics of body tissues) and psychological (the mind).

Physiological effects

It takes some time for the body to change from its basic ‘tick over’ at rest to a point at which it is ready to perform maximally. If vigorous exercise is started immediately from rest, the heartbeat is speeded up with a sudden jolt instead of increasing gradually, and the beats of the heart can become irregular (ectopic beats), rather than showing their normal smooth rhythm. These changes affecting the heart can be potentially very serious in the older or less active individual, and especially in those with a history of heart or circulatory problems.

Effects on the heart

Over 40 years ago a research study was conducted which clearly illustrated the effects of a warm-up on the heart. Researchers took a group of men with no history of heart problems and made them run vigorously on a treadmill for 10-15 seconds without a warm-up. In 70 per cent of these subjects, abnormal changes were seen on an electrocardiogram (ECG) machine. These changes, called ischaemia, showed that insufficient blood was getting to the heart muscle, a potentially very dangerous situation. However, when the same subjects ran on the treadmill after performing a warm-up, the ECG changes were greatly reduced, and in many cases the heartbeat was completely normal. In addition, blood pressure (BP) was taken when the subjects ran on the treadmill both with and without a warm-up. Blood pressure for those who used a warm-up was on average 12 per cent lower than those who did not.

Effect on body tissue

A warm-up will allow the body tissues to work more efficiently. Normally, while relaxed, the muscles receive only about 15 per cent of the total blood flow. The rest of the blood goes to the body organs such as the brain, liver and intestines. During vigorous exercise, because the muscles need far more fuel to provide energy, their requirement for blood increases to 80 per cent of the total blood flow. It takes time to re-route this blood by opening some blood vessels and closing others, and if the muscles are required to perform maximally before the blood flow has changed they will work inefficiently.

Lactic acid formation

The body can produce energy by two methods: aerobically (with oxygen) and anaerobically (without oxygen). The aerobic method is preferable, because when we work anaerobically we produce a waste product called lactic acid. Unfortunately, we cannot work aerobically straightaway as it takes time to switch the aerobic system on. If we start intense exercise without a warm-up, the aerobic system does not have enough time to switch on; we therefore have to provide energy anaerobically, with resultant lactic acid formation.

The function of a warm-up is to ‘switch on’ the aerobic system and allow the body to reach a steady state where the energy provided by the body exactly matches its requirements through exercise. Once this is done, less waste is produced and so our recovery after exercise will be much faster.

Mechanical effect

The mechanical effects of warm-up occur as a direct result of tissue heating. Chemical reactions involved in the production of energy for the working muscle and the removal of waste products are speeded up with warmth. In addition, nerve impulses travel faster when a nerve is warm. The effects of a warm-up on nerve conduction is particularly important for the speed of reflexes, which protect the muscles from injury, an essential component of core stability.

When a substance is heated it becomes more pliable, and this is exactly the same for the body tissues and the fluids within joints. Fluids are fairly stiff (viscous) at rest but become thinner and more malleable with movement. The facet joints of the spine contain fluid, as do the discs, so the spine is affected by this change in viscosity. The overall effect of a warm-up on the spine is to make it less stiff and so make movements smoother and easier to control.

Psychological effects

Two effects are important here: arousal level and mental rehearsal.

Arousal level

Arousal level is how alert you are. There is a direct relationship between arousal and performance. Initially, as arousal increases so does performance. However, after a certain point an individual becomes too aroused (they are now ‘stressed’) and their performance suffers. As an illustration of this mechanism, imagine you have had a boring day and you arrive at the gym not really wanting to exercise. Your arousal level is low so your exercise performance will be poor. If you then go into an exercise class, however, the instructor, the music and the other people, will increase your
arousal level. You feel motivated and your exercise performance improves.

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