Questions on exercise, sports medicine and performance-enhancing drugs

Question 1

Discuss whether athletes should be allowed to use performance-enhancing substances. Refer to different ethical positions in your answer.

Accepted Answer

B1 against, rights and duties: athletes have agreed to the rules of their sport and doping breaks them, so it is cheating B1 against, harm: the substances carry health risks, such as liver damage and heart disease from steroids or clots from EPO, and doses exceed medical ones B1 against, coercion or virtue ethics: clean athletes are pressured to dope to compete, and doping replaces fair play and effort, setting a poor example to young athletes B1 for, autonomy: informed adults should be free to take risks with their own bodies B1 for, relativist or utilitarian: the line is arbitrary, since altitude training has a similar effect to EPO legally, and supervised legal use might cause less harm than covert use that testing misses B1 a reasoned conclusion that weighs the two sides, for example that coercion removes the autonomy the main argument for doping relies on

Question 2

Using the same table, evaluate the claim that exercise prevents type 2 diabetes.

Accepted Answer

B1 the proportion developing diabetes falls as activity rises, from 9.0 to 6.5 to 5.0 to 4.6 per cent, a negative correlation B1 the steady fall is a dose-response relationship and the sample is large, both of which support a causal link B1 but the study is observational and the groups were not allocated at random, so confounding variables such as diet, body mass, smoking or income may explain some of the difference B1 reverse causation is possible: people with early or undiagnosed illness may have been less active B1 the data show a correlation consistent with the claim but do not prove that exercise prevents diabetes; 'prevents' is too strong, since some active people still developed it, and 'reduces the risk' is what the data could support

Question 3

Explain how a lack of exercise increases a person's risk of developing type 2 diabetes.

Accepted Answer

B1 less energy is used each day, so with the same diet more is stored as fat and the person is more likely to become obese B1 contracting muscle takes up glucose from the blood, moving glucose transporters into its membrane without needing insulin, so less glucose is removed when muscles are inactive B1 without regular exercise, and with obesity, muscle and liver cells become less sensitive to insulin (insulin resistance) B1 the pancreas must secrete more insulin to control blood glucose, and when its β cells cannot keep up the blood glucose concentration stays high

Question 4

Explain why many years of high-impact training can lead to osteoarthritis of the knee, and why the damage is slow to repair.

Accepted Answer

B1 the ends of the femur and tibia are covered with articular cartilage, which reduces friction and absorbs shock B1 repeated impact loading wears the cartilage thin, and the menisci that spread the load can be torn B1 once the cartilage is worn the bone surfaces rub, causing pain, swelling and stiffness, which is osteoarthritis B1 cartilage has no blood supply, so few nutrients and cells reach it and it repairs slowly and poorly

Question 5

A footballer has a torn meniscus repaired by keyhole surgery rather than open surgery. Explain why she is likely to return to training sooner.

Accepted Answer

B1 the arthroscope and instruments go in through two or three small incisions rather than one long cut B1 less skin, muscle and other tissue is cut, so there is less to heal, less pain and less blood loss B1 the smaller wound gives a lower risk of infection B1 she can go home sooner and start moving the joint and rehabilitation earlier, so less muscle wastes

Question 6

Anabolic steroids are lipid-soluble drugs related to testosterone. Explain how they increase muscle mass.

Accepted Answer

B1 being lipid-soluble, they diffuse through the phospholipid bilayer of the muscle cell membrane B1 they bind a receptor protein inside the cell, and the hormone-receptor complex enters the nucleus B1 the complex acts as a transcription factor, binding DNA and switching on the genes for muscle proteins B1 more mRNA is transcribed and translated, so more muscle protein is made and the fibres grow larger and stronger

Question 7

Explain how injecting EPO can improve the performance of an endurance cyclist, and why it is dangerous.

Accepted Answer

B1 EPO stimulates the bone marrow to produce more red blood cells B1 so the blood carries more haemoglobin and more oxygen per litre to the muscles B1 aerobic respiration can supply ATP at a higher rate, so the cyclist relies less on anaerobic respiration and builds up less lactate, delaying fatigue B1 the blood becomes thicker and more viscous, raising the risk of clots, stroke and heart attack, especially when dehydrated

Question 8

Describe the J-shaped curve proposed to relate the risk of upper respiratory tract infection to the amount of exercise, and give one change in the immune system after intense exercise that could explain it.

Accepted Answer

B1 moderate exercise lowers the risk below that of a sedentary person, the lowest point of the curve B1 very heavy or prolonged intense exercise raises the risk above that of a sedentary person B1 after intense exercise there are fewer, or less active, lymphocytes such as natural killer cells in the blood, or less phagocyte activity, or less IgA in saliva, or raised cortisol suppressing the immune response

Question 9

The table shows the results of a ten-year study of 20 000 adults. The data were constructed for this question rather than measured. Calculate the percentage of each of the two extreme groups that developed type 2 diabetes, and the percentage reduction in risk from the least active group to the most active.

Accepted Answer

M1 none: 360 ÷ 4000 × 100 = 9.0 per cent; over 5 hours: 184 ÷ 4000 × 100 = 4.6 per cent M1 percentage reduction = (9.0 − 4.6) ÷ 9.0 × 100 A1 = 49 per cent (48.9)

Question 10

Using the marathon study in the previous question, suggest three reasons, other than suppression of the immune system by exercise, why the finishers reported more colds.

Accepted Answer

B1 the finishers spent the race and its build-up in crowds, and travelled, so were more exposed to pathogens B1 symptoms were self-reported rather than confirmed in a laboratory, and runners who expect to fall ill may report minor symptoms more often B1 the two groups were not allocated at random and differ in other ways, such as sleep, diet or training load before the race, which are confounding variables

Question 11

Explain how a carbon-fibre running blade allows an athlete with a lower-leg amputation to sprint.

Accepted Answer

B1 it is attached to the residual limb by a socket moulded to fit, which spreads the load and transmits force to the blade B1 the curved blade bends when the athlete's weight comes onto it, storing elastic strain energy B1 it springs back as the foot leaves the ground, returning much of that energy to propel the athlete forward

Question 12

Sleeping in an altitude tent and injecting EPO both raise an athlete's red blood cell count. Suggest why the first is permitted and the second is prohibited.

Accepted Answer

B1 the tent works through the body's own response: low blood oxygen makes the kidneys secrete more of the athlete's own EPO B1 that response stops once blood oxygen recovers, so the red cell count stays within a natural range and the health risk is small B1 injected EPO has no such limit and can make the blood dangerously viscous, so it meets the criteria of enhancing performance, risking health and being against the spirit of sport

Question 13

State two possible disadvantages to health of exercising too much.

Accepted Answer

B1 wear and tear on joints, such as wearing away of the articular cartilage, leading to osteoarthritis, or damage to ligaments, menisci or tendons B1 suppression of the immune system after prolonged intense exercise, giving a higher risk of infections such as upper respiratory tract infections

Question 14

In a study constructed for this question, 225 of 1500 runners who finished a marathon reported symptoms of a cold in the following week, compared with 20 of 500 people who entered but did not run. Calculate how many times more likely the finishers were to report symptoms.

Accepted Answer

M1 finishers 225 ÷ 1500 = 15 per cent; non-runners 20 ÷ 500 = 4 per cent A1 15 ÷ 4 = 3.75 times (accept 3.8)

Weekly moderate activity	Adults followed	Developed type 2 diabetes
None	4000	360
Under 2.5 hours	6000	390
2.5 to 5 hours	6000	300
Over 5 hours	4000	184

Weekly moderate activity	Adults followed	Developed type 2 diabetes
None	4000	360
Under 2.5 hours	6000	390
2.5 to 5 hours	6000	300
Over 5 hours	4000	184