The long-term effects of exercise on the body

Practical application/explanation

After we exercise over a period of time, adaptations take place within the body. The main adaptations take place in the:

• heart
• lungs
• vascular system
• blood
• muscles

Physiological adaptations from aerobic training

Adaptations to the lungs

After training aerobically over a period of weeks, there will be changes in the lungs, which include:

• improved efficiency/strength of the respiratory muscles (diaphragm and intercostal muscles),
• increased proportion of alveoli (air sacs which diffuse oxygen into the capillaries),
• increased number of capillaries, which diffuse the oxygen from the alveoli into the blood,
• increased tidal volume and vital capacity.

This means that more oxygen can be consumed and transported from the alveoli into the capillaries and into the red blood cells. The remaining systems then transport the oxygen to the working muscles and eventually back out as CO2.

Adaptations to the heart

The heart gets bigger and stronger (cardiac hypertrophy) with aerobic exercise.

This means the heart can:

• hold more blood, increasing the stroke volume (amount of blood pumped out of the heart per beat),
• beat with more force, which again will increase stroke volume.

The result of this will be:

• a reduction in resting heart rate (number of beats per minute),
• an increase in maximum cardiac output (amount of blood pumped out of the heart in 1 minute).

Overall there will be more blood going to the working muscles, allowing the athlete to exercise for longer in the aerobic zone (taking longer to reach anaerobic threshold) as the exercise intensity increases.

Adaptations to the vascular system

• Vasomotor control – the arteries will become more elastic, allowing them to vasodilate (become wider) and vasoconstrict (become narrower) more efficiently.

This improves the transportation of the blood to the working muscles. This is also a real health benefit by reducing the potential impact of hypertension (high blood pressure).

Changes in the blood

• Increased number of red blood cells and therefore more haemoglobin.

This will mean that the blood will be able to carry more oxygen to the working muscles.

This improves the transportation of the blood to the working muscles. This is also a real health benefit by reducing the potential impact of hypertension (high blood pressure).

Adaptations to the muscles

• Larger numbers of capillaries present to diffuse the oxygen into the muscles.
• Larger number of mitochondria (power plant of the cell, which converts oxygen and food into energy).
• Increased amounts of myoglobin (concentrated form of haemoglobin that transports the oxygen into the mitochondria).

This will mean that greater amounts of oxygen can be carried into capillaries and then used for energy within the muscle (mitochondria).

Adaptations to the bones and joints

• Exercise stimulates deposition of calcium which makes the bones stronger.
• Tendons and ligaments increase in strength and flexibility.

Adaptations to the body after anaerobic exercise

Anaerobic exercise includes such activities as sprinting, weight training, plyometrics and anything where a sportsperson is working close to their maximum. Anaerobic adaptations are fewer than aerobic but are no less important.

When individuals train and predominantly use the ATP-PC system, then the adaptation as a result of such training is different from athletes who predominantly use the anaerobic glycolysis system. For example, an athlete who undertakes power and strength training will get the following adaptations:

• muscle hypertrophy (increase in size of the muscles),
• increased creatine phosphate stores,
• co-ordination of the neural system improves, i.e. the firing patterns of the neural impulses is more co-ordinated and makes the sporting movement more efficient,
• an increase in the production of growth hormones.

If athletes did longer duration anaerobic training such as 200m and 300m interval sprints, then the following adaptations are more likely:

• a greater tolerance to lactic acid (also known as buffering capacity of the muscles), allowing exercise to go on for longer,
• an increase in muscle glycogen stores.

As well as the adaptations already mentioned above, recent research that high intensity exercise over a period of time, e.g. 30–40 sec bouts, can have what are considered aerobic adaptations. Such adaptations include:

• cardiac hypertrophy (resulting in increased stroke volume and max. cardiac output),
• increase in strength of the diaphragm and intercostal muscles (increasing the efficiency of the breathing mechanism),
• increased density of alveoli and capillaries within the lungs (increases the rate of gaseous exchange),
• increased number of red blood cells (increases the oxygen carrying capacity of the blood),
• increased elasticity (vasomotor control) of arteries and arterioles (allows greater volume of oxygenated blood to pass through the vessels),
• increased capillary density, mitochondrial density and myoglobin content in the muscles (increases the amount of oxygen into the muscles, converting it to energy).

Improvements to sporting performance

Anaerobic adaptations will mean:

• Because of increased muscular hypertrophy, the performer will be able to increase the amount of force, power output, speed and strength to a given sporting situation.
• The performer will also be able to remain in the anaerobic zone for longer, due to the increased energy stores (CP and glycogen) and increased tolerance to lactic acid.
• When using high-intensity activity over a longer duration, then similar improvements in performance will occur, e.g. increased VO2 max., higher anaerobic threshold.