Which of the health related components is considered the amount of force a muscle or group of muscles can exert when they contract?

Whether you are a student who wants to be fitter, a netballer who wants a faster more powerful throw, a sprinter who wants to win that race or a weightlifter who wants to lift heavier weights, you are trying to make your muscles work better.

There are three major factors that affect how well your muscles perform – strength, power and endurance.

Strength

Muscle strength is also a result of the combination of three factors:

• Physiological strength, which depends on factors such as muscle size, the cross-sectional area of the muscle and responses to training.
• Neurological strength, which looks at how weak or how strong the signal is that tells the muscle to contract.
• Mechanical strength, which refers to a muscle’s pulling force and the way those forces can be changed using bones and joints as levers.

When we talk about the strength or muscles, we are describing the maximum force a muscle can exert. Muscle strength is directly dependant upon the size of the cross-sectional area of muscle, so if after a period of training, you increase your muscle size by 50%, you will also increase the force the muscle can develop by 50%.

For every 1 square centimetre of cross sectional area, muscle fibres can exert a maximum force of approximately 30–40 newtons (the weight of a 3–4 kg mass).

Example: Emily can lift 21 kg (210 newtons force) using muscles that have a cross-sectional area of 6 cm2. Use this formula to work out how many newtons per square centimetre her muscles can pull with:

Emily’s friend Alisha has larger muscles that have a cross-sectional area of 8 cm2. Use this formula to work out what weight Alisha should be able to lift if her muscle tissue is similar to Emily’s:

Power

When muscles contract or stretch in moving a load they do work, and energy is transferred from one form to another. The power of muscles refers to how quickly the muscles can do this work and transfer the energy.

Example: A weightlifter lifts 100 kg up a distance of 1.5 m. 100 kg has a weight force of 1000 newtons. Use this formula to calculate the work done (energy transferred) by the weightlifter:

If the weightlifter lifts the 100 kg explosively and takes only 0.5 seconds to make the lift, use this formula to calculate the power their muscles produce:

Where does the energy come from and where does it go?

The energy for muscle contraction comes from glucose transported by the blood and deposited in muscle tissues. In the weightlifter example, the energy has been transformed to gravitational potential energy. Also, heat energy will be generated in the muscle tissues themselves. This means that the muscles will have transferred even more energy than the amount calculated above.

Putting the relationships together

There are three different equations that can be simplified to make an even more useful equation:

Because

the formula can be rewritten: power = force × velocity

Sports scientists use this formula to measure the power profiles of particular sets of muscles by measuring both the force of the muscles and the speed with which they are contracting or lengthening. They have found that the greatest power is produced when the load is much less than the maximum load on the muscles.

Endurance

Muscle endurance refers to how well the muscles can exert and hold maximum force over and over and over again.

Tancred (1995)[1] believes that: "One of the misconceptions in the sports world is that a sports person gets in shape by just playing or taking part in their chosen sport. If a stationary level of performance and consistent ability in executing a few limited skills is your goal, then engaging only in your sport will keep you there. However, sportsmen and women must participate in year-round conditioning programs if they want the utmost efficiency, consistent improvement, and balanced abilities. The bottom line in sports conditioning and fitness training is stress, not mental stress, but adaptive body stress. Sportsmen and women must put their bodies under a certain amount of stress (overload) to increase physical capabilities."

Health & Fitness

The World Health Organization (WHO) defined health in its constitution of 1948 as "a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity".

Fitness is the ability to meet the demands of a physical task.

The Components of Fitness

Basic fitness can be classified into four main components: strength, speed, stamina and flexibility. However, exercise scientists have identified nine components that comprise the definition of fitness (Tancred 1995)[1]:

• Strength - the extent to which muscles can exert force by contracting against resistance (e.g. holding or restraining an object or person)
• Power - the ability to exert maximum muscular contraction instantly in an explosive burst of movements. The two components of power are strength and speed. (e.g. jumping or a sprint start)
• Agility - the ability to perform a series of explosive power movements in rapid succession in opposing directions (e.g. Zigzag running or cutting movements)
• Balance - the ability to control the body's position, either stationary (e.g. a handstand) or while moving (e.g. a gymnastics stunt)
• Flexibility - the ability to achieve an extended range of motion without being impeded by excess tissue, i.e. fat or muscle (e.g. executing a leg split)
• Local Muscle Endurance - a single muscle's ability to perform sustained work (e.g. rowing or cycling)
• Cardiovascular Endurance - the heart's ability to deliver blood to working muscles and their ability to use it (e.g. running long distances)
• Strength Endurance - a muscle's ability to perform a maximum contraction time after time (e.g. continuous explosive rebounding through an entire basketball game)
• Coordination- the ability to integrate the above-listed components so that effective movements are achieved.

Of all the nine fitness elements, cardiac respiratory qualities are the most important to develop as they enhance all the other components of the conditioning equation.

Physical Fitness

Physical fitness refers to an athlete's capacity to meet the varied physical demands of their sport without reducing the athlete to a fatigued state. The components of physical fitness are (Davis 2000)[2]:

• Body Composition
• Endurance
• Flexibility
• Strength
• Speed

Motor Fitness

Motor Fitness refers to an athlete's ability to perform successfully in their sport. The components of motor fitness are (Davis 2000)[2]:

• Agility
• Balance
• Coordination
• Power (speed & strength)
• Reaction Time

Improving your condition

Identify the most important fitness components for success in your sport or event. Then, design sport/event specific conditioning and training programs to enhance these fitness components and energy systems.

Conditioning Exercises

The following are examples of general conditioning exercises:

Why should I exercise regularly?

Not convinced about the benefits of a regular training regime, then read the benefits of exercising page.

I am new to training, so what should I do?

Visit the general fitness training program page to get an insight into a simple weekly training program that will help develop your general fitness level.

Tests for fitness components

In their research, Suni et al. (1996)[3] found that the following tests appeared to provide acceptable reliability as methods for the field assessment of health-related fitness for adults:

• Standing on one leg with eyes open for balance
• Side-bending of the trunk for spinal flexibility
• Modified push-ups for upper body muscular function
• Jump and reach and one leg squat for muscular leg function

References

1. TANCRED, B. (1995) Key Methods of Sports Conditioning. Athletics Coach, 29 (2), p. 19
2. DAVIS, B. et al. (2000) Training for physical fitness. In: DAVIS, B. et al. Physical Education and the study of sport. London: Harcourt Publishers, p.121-122
3. SUNI, J. H. et al. (1996) Health-related fitness test battery for adults: aspects of reliability. Archives of physical medicine and rehabilitation, 77 (4), p. 399-405

Page Reference

If you quote information from this page in your work, then the reference for this page is:

• MACKENZIE, B. (1997) Conditioning [WWW] Available from: https://www.brianmac.co.uk/conditon.htm [Accessed