B5
Katherine Castro & Pedro Pablo Talledo

• Definition: Fitness is the state or condition of being fit; suitability or appropriateness. Good health or physical condition, especially as the result of exercise and proper nutrition.
• Training can improve fitness, especially by improving the pulmonary and cardiovascular function, but there may also be some inherited elements to fitness, in particular the distribution of fast and slow muscle fibers.

• http://www.brainpop.com/health/personalhealth/fitness/pre view.weml#

Discuss speed and stamina as measures of fitness
• Speed is the rate at which a movement is performed. The time taken for a movement or series of movements must be measured .
• For example, a swimmer might record the minimum time taken to swim 50m.
• Stamina is the ability to continue an exercise for a long time. The maximum duration of an exercise ifs measured
• for example, the maximum number of press-ups that an athlete can perform.

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Slow muscle fibers have: an excellent blood supply with many blood capillaries. Because they contain large amount of myoglobin, they appear red in colour.
• They have many mitochondria and so are rich in oxidative enzymes.
• Their aerobic capacity is large and because they do little or no anaerobic cell respiration they have a very high stamina.
• Their strength is only moderate.
• Slow muscle fibres usually contain some glycogen, a polysaccharide that can be use as a store of glucose, but they mostly rely on respiratory substrates supplied by the blood system during exercise.
• Contract slowly but they keep going for a long time. Slow muscle fibers are good for endurance activities long distance running or cycling.

• Fast muscle fibres have few mitochondria
• are rich in the enzymes of glycolysis and have moderate blood supply.
• They contain little myoglobin so are pale in colour.
• They contract more rapidly than slow muscle fibers and have much greater strength (exert more force per unit area). However, their stamina is much less, because of the rapid accumulation of lactate and the development of an oxygen debt during intense exercise
• Contract quickly but get rapidly tired
• Fast muscle fibers are good for rapid movements like jumping to get a ball or sprinting.

• http://www.brainpop.com/search/search.weml?keyword= muscle+fibers

B.5.4 Distinguish between the effects of moderate-intensity and high-intensity exercise on fast and slow muscle fibres.
• Fast fibers : can release large amounts of energy for a short period of time by anaerobic respiration. This is good for high-intensity exercise, for example 100m sprint races.
• Slow fibers : Release energy more slowly by aerobic cell respiration, but can continue for longer, so are useful in endurance events, for example marathons, moderateintensity exercise.
• Moderate-intensity exercise, such as long-distance running or swimming, encourages the development of slow fibers. High-intensity exercise, for example sprinting or weight lifting, encourages the development of fast muscle fibers.

Aerobic and anaerobic respiration video
• http://www.youtube.com/watch?v=PQMsJSme780

B.5.5 Discuss the ethics of using performance-enhancing substances, including anabolic steroids.
• Drugs can be used to enhance performance in sport, but there are strong ethical arguments against their use.
• Drug-users gain an unfair advantage in competitions. For example, in Men’s 100m finals in a recent Olympic
Games, a high proportion of athletes had probably been taking anabolic steroids.
• Criminals profit from the sale of banned drugs. For example there have been prosecutions of people who have been making substantial profits from the illegal sale of anabolic steroids. If athletes decided not to use these anabolic steroids, these profits could not be made.

B.5.5 Discuss the ethics of using performance-enhancing substances, including anabolic steroids.
• Ethical arguments in favor of legalizing performance enhancing substances
• Their use might overcome natural variation in physiology, for example, variation in testosterone levels. If all athletes were able to use them, competition might be fairer.
• If they do enhance performance, spectators might gain more enjoyment from watching sports.

• The long-term health of sportsmen and women who are encouraged to take them may be damaged.
• For example anabolic steroids can cause men’s testes to become smaller and sperm counts to be low. Because anabolic steroids resemble testosterone, they can interfere with women’s reproductive system and cause abnormal menstrual cycles. High doses can cause liver disease and there have been reports of athletes who take anabolic steroids suffering from emotional problems, with inappropriately aggressive outbursts.