Effect of gravity on exercise
Gravity influences muscle contraction by trying to pull the body or body part down to the floor (if acting against gravity). For example, the abdominal curl takes place against gravity trying to pull the upper body down to the floor, making it harder. The rectus abdominis muscle is the agonist, working concentrically when the spine is flexed and eccentrically when lowered. If flexion of the spine takes place whilst standing up, the movement takes place with gravity, making it easier. The erector spinae is the agonist, working eccentrically when the spine is flexed and concentrically when raised. This exercise is ineffective for the abdominals. Changing the body position in relation to gravity changes the emphasis of the exercise in terms of the muscles used.
Altering lever length can also affect how hard an exercise is. For example, with the abdominal curl, the easiest version involves performing the exercise with the hands on the thighs. To make it progressively harder, cross the hands over the chest, place the hands by the temples, or extend the arms behind the head. With the press up, altering lever length and the effects of gravity can change the intensity of the exercise. The easiest version involves resting the hands on some object (so they are higher than the feet), and the hardest version involves resting the feet on some object (so they are higher than the hands). Performing a box press up (knees on the floor) is easy than a full press up (feet on the floor).
The FITT principle
The FITT principle is a set of guidelines that helps to make sure that all aspects of training are included in the exercise programme. All training should include the following:
- Frequency – the number of training sessions per week should be sufficient to bring about improvements, but allow enough recovery time (particularly after high intensity activities)
- Intensity – how hard an individual works must be set at the correct level to bring about change to systems of body. Level or gradient, speed, resistance, lever length and range of movement all affect intensity
- Time – how long an individual works for in a session for each training session should be relative to individual’s fitness levels. For the same intensity, time spent in training should be gradually raised as fitness levels increase
- Type of training refers to activities included in training programme and reflects specific needs of the individual
As adaptation and improvement takes place, FITT needs to be reviewed and updated so the individual continues to improve through their training.
Individual factors influencing training potential
- Physical differences can affect health and fitness. Being the wrong weight can lead to health problems such as coronary heart disease (CHD) and high blood pressure (hypertension). Height and weight tables give a guide to correct weights but are often very inaccurate as they do not take into account muscle is heavier than fat – it is much more accurate to measure fat percentage. To be healthy generally requires a body fat of less than 20% for men and 30% for women.
- As bodies age, muscles, including heart, lose ability for long endurance events or high intensity events requiring strength and power. Flexibility and heart rate decrease with age, bones get lighter, joints get stiffer, body fat increases and movements get slower. These can be minimised by continuing to exercise and participate in physical activity throughout life.
- Gender – up to the age of 11, there’s very little difference in the physical capabilities of males and females. After this, differences emerge. Men usually have more muscles than women and are normally stronger. Puberty releases the male hormone testosterone promoting growth of muscle and bone. This also leads to men generally being more powerful and faster. Males tend to be better than females at transporting oxygen as they have a larger heart, lungs and more blood. Their red blood cells contain haemoglobin. Women have, on average, 30% more fat than men, and as they get older, changes in their hormonal system can lead to osteoporosis – a condition where bones become more brittle. Males are usually heavier and larger than females because males have bigger bones. Males also have a narrower pelvis, making it easier to transmit power between the legs and trunk. Females tend to score higher on flexibility. Differences are not be so pronounced however, if viewing attributes in relative rather than absolute terms.
- Disability comes in many forms and can be caused in a variety of ways. A disability means that part of the body does not function properly and may occur with age (such as poor eyesight), or be inherited (i.e. born with the disability), or happen through an accident. Some specific conditions can affect health and fitness, e.g. arthritis can affect mobility.
- Lifestyle – everyone’s influenced by the environment in which they live and what they do in that environment. Some of these influences are potentially harmful, damaging health and/or having a negative effect on participation/performance in physical activity/sport.
- Smoking has serious consequences for health and fitness – increasing the likelihood of coronary heart disease (CHD) and respiratory diseases (reducing the capacity and efficiency of lungs), reducing the capacity of blood to carry oxygen, and negatively affecting gaseous exchange.
Excessive alcohol can have serious consequences for health and fitness, and has negative effects on coordination, balance, agility, slows down reaction time, can lead to an unjustified confidence in ability, or can give a mistaken assessment of a situation. These all result in people thinking they are capable of working outside their safe limits. Alcohol is also a diuretic – increasing loss of fluid through urination. As water is vital to performance, alcohol and physical activity must not be mixed.
- Drugs come in various forms and can have a very detrimental effect on health and fitness.
- Stress and anxiety can affect health if continued over long periods of time – they can cause high blood pressure and heart disease, and may also be linked to cancer.
- Exercise if done on a regular basis, increases health and fitness.
- Eating disorders are illnesses that make individuals starve themselves or binge because they have a craving to be thin and can have very serious consequences for health and fitness. Anorexia nervosa is basically self-inflicted starvation – individuals suffering from this are obsessed with their appearance, thinking they are too fat. Bulimia nervosa is usually characterised by binge eating followed by feelings of self-disgust and forced vomiting. Individuals who suffer from either of these become obsessed with their weight and their self-image (how they see themselves), and often participate in vigorous exercise in an effort to control and improve them. Compulsive eating disorder refers to a condition in which the individual has episodes of irrepressible over eating. Some estimate that around 20% of those suffering from obesity also suffer from binge eating. Sufferers do not normally make themselves vomit after binging or become obsessed with exercise.