Components of fitness

What is fitness?

Fitness means different things to different people. Probably the best definition is that fitness refers to “the ability to meet the physical demands of everyday life without excessive fatigue and still have something in reserve.” When considering fitness, it is important to ask the question “fit for what?”

Participation in any activity/exercise regime will alter the way various body systems work. Whether the body can cope with these changes depends on how prepared it is for the demands that are being made on it. If the demands of the exercise are too great for a person’s body systems, they will have to stop. If regular demands are made on the body, it adjusts to these, and exercise becomes easier. This is known as the principle of adaptation.

Fitness is a mixture of many different physical qualities. Everybody needs these qualities to a certain extent. The degree to which an individual has these qualities determines their health and ability in sport. These are known as health-related fitness components and motor fitness components (also known as sports-related or skill-related fitness).

Health-related fitness

(1) Cardiovascular or aerobic fitness

This can be defined as the ability to perform exercise over a long period of time without getting tired. It depends on the capacity of the heart, circulatory system and lungs to meet the demands of the body for a sustained period of activity. Aerobic exercises work the cardiovascular and respiratory systems – improving the efficiency of the transportation and utilisation of oxygen to produce energy. Regular aerobic exercise is an excellent way to promote health. Aerobic exercise is any activity that is continuous, rhythmical and uses large muscle groups under low tension. The aerobic energy system provides most of the body’s needs for energy (except during periods of intense work).

When an individual starts exercising, the working muscles demand more oxygen to be delivered. It may take up to 3 minutes for the heart, lungs and circulatory system to meet this new demand, and in the meantime the anaerobic systems will meet the needs. A warm up helps to mobilise the aerobic system so that it is ready for use in the main activity, and as long as the exercise is continuous and submaximal, most of the energy will continue to be produced in this way.

Short-term effects of aerobic exercise

  • Increase in blood pressure
  • Increase in heart rate
  • Increase in stroke volume
  • Cardiac output increases
  • Increase in breathing rate
  • Build-up of carbon dioxide in the blood
  • Capillaries dilate
  • More blood is circulated around the body
  • Blood is diverted from soft organs to working muscles
  • Blood transports heat from muscles to surface of the body where it can escape

Long-term adaptations to aerobic exercise
Adaptations to the heart:

  • Chambers of heart become larger in size and chamber walls become thicker and stronger – especially true of left ventricle
  • Stroke volume increases
  • Resting heart rate decreases
  • Cardiac output increases
  • Heart rate recovery quicker

Adaptations to blood:

  • Blood volume increases
  • Number of red blood cells and haemoglobin increase in number
  • Fat levels in blood decrease
  • Lactic acid in blood is dealt with better

Adaptations to blood vessels:

  • Arteries become larger and more elastic, reducing risk of arteries hardening
  • More capillaries in and around muscle tissue – capillarisation
  • Increased capillarisation in and around heart and lungs
  • Blood pressure lowered due to capillarisation

Adaptations to muscles:

  • Aerobic energy system becomes more efficient with increase in size and number of mitochondria and increase in aerobic enzyme activity – the muscles can produce energy aerobically for longer and at higher intensities
  • Slow twitch muscle fibres increase in size

Adaptations to bones:
• Bones become stronger as more calcium is produced
• Hyaline cartilage at end of bones becomes thicker and is better able to absorb shock
• Weight bearing aerobic exercise such as walking are far better for bones than non-weight bearing aerobic exercise such as swimming or cycling

Adaptations to ligaments and tendons:

  • Tendons become stronger
  • Ligaments stretch a little

Adaptations to body fat:

  • Less carbohydrate and more fat is used as fuel

Adaptations to lungs:

  • Diaphragm and intercostal muscles become stronger
  • Volume of air taken in with each breath increases
  • Number of capillaries surrounding alveoli increases
  • More oxygen enters blood and more carbon dioxide leaves
  • VO2max (the maximum amount of oxygen that can be taken in and used per minute) increases

Health benefits of regular aerobic exercise
Aerobic exercise makes the cardio-respiratory system work harder, making the heart stronger and circulatory system and working muscles more efficient at transporting and using oxygen. This leads to the following benefits:

  • Blood pressure decreases
  • This leads to long-term cardiac benefits and a significantly reduced probability of developing coronary heart disease (CHD) in later life
  • Aerobic training can help to reduce anxiety and tension immediately and for hours after training. It can also improve an individual’s self-image and self-confidence
  • Regular aerobic training is excellent at controlling or reducing weight – maintaining lean muscle tissue and resting metabolic rate, whilst improving the body’s ability to use fat as an energy source
  • Regular aerobic training helps muscles to use glucose more efficiently
  • More HDLs (high density lipoproteins) – a type of cholesterol that is good for the CV system
  • Less LDLs (low density lipoproteins) – harmful cholesterol. Overall effect is a reduction in cholesterol
  • Regular aerobic weight bearing exercise such as walking and running increase bone density and can help to prevent osteoporosis
  • Sedentary individuals who carry out aerobic exercise on a regular basis will start noticing benefits within 4 weeks and will see definite changes in 8 weeks. These individuals will be able to carry out everyday tasks much easier and with less fatigue. These training effects are typically produced in 8 to 12 weeks of starting an aerobic exercise programme

(2) Muscular strength
Muscular exertion is needed for almost every task in everyday life. Some require short bursts of heavy work – strength; or repeated/longer periods of lighter work – muscular endurance. Both muscular strength and endurance are important for health and fitness, as well as improving sporting performance.

Muscular strength is the maximum force that can be generated by a muscle group against resistance. To improve muscular strength, lift a heavy resistance for a few repetitions (high load – low reps). The main effect of this type of training is hypertrophy (bigger muscles).

Adaptations to muscular strength training

  • Growth in muscle tissue – hypertrophy – especially true of fast twitch muscle fibres
  • With sufficient rest and recovery after training, extra actin and myosin are laid down in recovering muscle fibres leading to increased muscle size and strength
  • Growth is made faster by male hormone testosterone – which may partly explain strength differences between men and women
  • Increased efficiency of recruiting muscle fibres – neuromuscular pathways – larger amount of fibres within muscle can be used at any one time, leading to stronger muscle contractions – especially true in the first few weeks of resistance training – rapid gains in strength

(3) Muscular endurance
This is the ability of a muscle group to apply a sub-maximal force against a resistance over an extended period. To improve muscular endurance, a light resistance should be lifted for many repetitions (low load – high reps). The main effect of this type of training is increased capillarisation and an increase in the number and size of mitochondria.

Adaptations to muscular endurance training

  • Strength training is mainly fuelled by CP system – muscular endurance is fuelled by the lactic acid system. Build-up of lactic acid in muscle leads to fatigue
  • Increased capillaries in and around muscle
  • Increase in size and number of mitochondria
  • Improves supply of oxygen to muscle
  • Improves muscle’s ability to use oxygen
  • This offsets fatigue resulting from the build-up of lactic acid and improves muscular endurance
  • Efficiency of muscle fibre recruitment improved, especially true of slow twitch muscle fibres
  • Hypertrophy of slow twitch muscle fibres is not as marked as that of fast twitch fibres, muscle looks more toned rather than bulky

Muscular strength and endurance lie on a continuum with maximum strength at one end and muscular endurance at the other.

Health benefits of muscular strength and endurance (mse) training

  • Greater ability to deal with everyday tasks
  • Better, more balanced posture and body shape
  • Increased resting metabolic rate – helping to control weight
  • Improved self-image and self-confidence
  • Increased bone density – helping to prevent osteoporosis and bone fractures in later life
  • Increased strength in tendons and ligaments
  • Decreased risk of injury – better able to avoid/resist injuries from impacts or falls
  • Improved performance in sport

(4) Flexibility
Flexibility or suppleness is a measure of the maximum range of movement (ROM) possible at a joint. Flexibility is specific to particular joints. Flexibility exercises increase ROM at a joint by moving joints just past its point of resistance – when muscle contracts and tension is felt. Good flexibility is vital for improving sports performance, as well as health. Stretching helps to reduce risk of injury and allows use of strength over greater range of movement.

There are 5 main ways of stretching:

  1. Static stretching involves extending limbs beyond normal range and then holding in position
  2. Active stretching involves extending movement beyond normal limit using strength of opposing (antagonist) muscles
  3. Passive stretching involves use of gravity, a partner or object to hold limb being stretched in end position
  4. Ballistic stretching involves use of jerking or bouncing movements to increase range of stretch – it is considered unsafe as it can cause tears
  5. PNF stretching (proprioceptive neuromuscular facilitation) contracts muscle first before stretching

The following factors affect flexibility:

  • Joint structure – shape of the surfaces of the articulating bones and the way they fit together
  • Tendons and ligaments that support the joint
  • Opposing muscle or fat may physically restrict movement
  • Flexibility decreases with age
  • Gender may affect flexibility

Benefits of flexibility training

  • Improved ability to cope with everyday tasks in an unrestricted manner
  • Improved performance in sport – muscles can exert greater force over greater distance and over a longer period
  • Posture improves – any imbalances due to inflexible muscles can be rectified
  • Helps to prevent injuries and helps to reduce muscle tension
  • Stretching can physically and mentally relax an individual
  • Stretching is performed in the warm up to prepare for the activity to come, and in the cool down for development

When stretching, tension is felt – this is the stretch reflex which helps to protect the stretched muscle from injury.

Motor (sports-related/skill-related) fitness

This can be defined as the ability to perform successfully in a given sporting context OR the level of physical fitness required for the demands of regular sporting activity. To achieve success in sport, all components of health-related fitness are needed. Sports-related fitness is more directly related to an athlete’s ability to perform the skills essential to their sport effectively and efficiently.

  1. Agility refers to the ability to change body position and direction quickly and with precision – moving in a controlled way when turning, stopping and starting quickly. It is a combination of speed, balance, power and coordination.
  2. Coordination refers to the ability to perform complex motor tasks involving several skills in sequence – the ability to carry out a series of movements smoothly and efficiently.
  3. Power is a combination of strength and speed that work together. It is defined as the ability to contract muscles with speed and force in one explosive act. The energy for power comes from the anaerobic CP system.
  4. Speed can be defined as the ability to move the body, or body part, over a specific distance in the shortest time possible. Speed can be initiated by different body parts and in some sports only one body part may be expected to move fast. Speed requires the quick supply of energy to muscles through the anaerobic energy systems.
  5. Reaction time refers to the time taken to respond to a given stimulus. Movement time is the time taken between the beginning of a response and the completion of the movement. Response time is the total amount of time between the given stimulus, the response to it and the completion of that response (response time = reaction time + movement time). Simple reaction time occurs when there’s one stimulus and no choices have to be made. Choice reaction time occurs when there’s a number of possible responses – longer reaction time.
  6. Balance is the awareness of the body’s position in a rapidly changing physical activity. Static balance – holding a position without movement. Dynamic balance – holding a position whilst moving. Maintaining balance requires keeping the body’s centre of gravity over the base of support. Balance is maintained through the eyes, ears and proprioceptive organs in joints all working together.

It is possible to improve these motor skills through regular training.

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