News stories about doping in sport offer an opportunity for students to learn about science – and much more besides, suggests Dr Joanna Rhodes…
The job of the athlete is to push him/herself to the limit of human capabilities and endurance. Sports such as athletics, cycling and swimming contain endurance events that require years of training. Sports scientists determine the biological principles that can help athletes to reach their maximum capability but what happens when an athlete decides they he or she needs to go further? Many athletes, past present and future have been, and will be, tempted to use drugs and other techniques to enhance their performance. But biologists, chemists and physicists are on their tracks – can they catch the cheats before they steal the prize from someone who deserves it?
In this lesson students investigate the biological factors that determine a person’s levels of fitness. It also allows students to assess their own fitness levels using a range of stimulating physical activities with cross-curricular links to PE. The lesson explores some of the techniques we use to determine the optimum personal best results for an individual athlete and explains how this data might provide evidence that an athlete is doping. Students will then explore some of the methods athletes might use to unfairly give them an advantage and how scientists are trying to remain one step ahead of the cheats.
WHY TEACH THIS?
Doping in sport regularly returns to news headlines. From Lance Armstrong to suspicions about coach Alberto Salazar this is an area that is likely to remain high profile. This is particularly the case since blood and urine samples can be held and re-tested for up to eight years to give the sport’s regulators time to catch up with the drugs cheats. The opportunities to make links between biology, physics and chemistry are superb, as is the cross curricular link with PE. Students are encouraged to think about the ethics of doping in sport enhancing their development in SMSC.
How fit are you?
To set up the lesson ask students to measure their resting pulse rate by counting the number of beats in 20 seconds while still in bed in the morning. They should multiply this figure by three to get their resting pulse rate. On arrival in the lesson they can repeat this to find any difference between resting pulse rate and the pulse rate during the day. They should then complete a 3-minute step challenge [AR1] timed with a stopwatch. I would recommend using a metronome to keep the class rhythm such as Metronome Online [AR2] or even a piece of music with a clear and motivating beat to complete a stepping exercise. Immediately following exercise the pulse rate should be taken for a full minute in silence, then repeated after five minutes. How many members of the class have returned to their original pulse rate? This simple fitness test helps to establish how it is the recovery time that is more crucial to fitness levels than peak heart rate. There are lots of potential errors and uncontrolled variables in this test. To extend students ask them how the test method could be improved to reduce these.
1 Generating power
Students may be used to recording the power consumption of an appliance such as a light bulb or microwave. However, power output in Watts is one of the most consistent and comparable measures of athletic performance. Tour de France cyclists produce about 500 Watts for the duration of a stage, and can hit an output of 1500 Watts in short bursts. The maximum power output you can produce depends on your weight. The average fit person can produce about 3W/kg, top amateurs produce 5W/kg and elite athletes achieve 6W/kg.
A straightforward way to measure power is using a rowing machine, since power output in Watts can usually be read directly from the screen. If you have access to a rowing machine students can carry out two activities that simulate real sport. One is to read the maximum power output a student can make the rowing machine read for ten continuous seconds. This is the ‘short burst’ value. In the second activity students record their average power output over a 500m distance. By dividing the power by their own weight they can compare their power with that of an elite athlete. Some of your students may also train as sports men and women – how do their results compare with other members of the class? Why not take a trip to a local gym to investigate power outputs? You could arrange for a small group of students to visit the gym to record power outputs for members of the gym and to discuss their results with the personal trainers.
2 Blood doping, sweat and tears
Increasing your power output through continuous training is the arduous life of an athlete. It is perhaps a natural consequence that some will try and take short cuts. A drug well known for doping in cycling is (erythropoietin) EPO. This natural hormone boosts the number of red blood cells the body produces and consequently increases the amount of oxygen and the power output. Another way to achieve this is altitude training – so how do you tell the cheats from the trainers? While EPO is produced in the body, the synthetic one has differences that can be detected using a test called Isoelectric Focusing. In this test synthetic and natural EPO from a sample migrate to different positions on a gel and can produce a different set of bands. You can simulate this kind of testing in the school laboratory using paper chromatography. By using leaf pigments rather than drugs, which is both visual and safer for students, you can give them an idea of how complex chemicals such as chlorophyll (green), xanthophylls (yellow), anthocyanin (red) and carotene (orange) can be separated and analysed. A detailed method can be found at Biology Junction [AR3]. Students might be interested to be shown the chemical structure of each of the pigment types to reinforce to students the complex nature of the chemicals their tests are separating and identifying.
STRETCH THEM FURTHER
Intake of oxygen is the key to improved power output and this is dependent on red blood cell count. Some athletes try and boost this by doping with their own blood. By taking blood from an athlete (perhaps while training at altitude) and storing it, that athletes red blood cell count can be boosted before a race by transfusing their own blood. This is almost impossible to chemically detect from samples. In detecting cheats some scientists think that power output could be helpful. Known drugs cheats such as Lance Armstrong could produce up to 7W/kg but values much above 6W/kg are considered to be suspicious and might open up an athlete to further scrutiny and testing.
Give your gifted and talented students a simplified opportunity to detect potential doping. They need to decide which athlete may require further tests or scrutiny as a result of the following data: In a time trial, three athletes competed.
- Athlete 1: has a mass of 70 kg and travelled at an average speed of 13.5 m/s against a force of 30N
- Athlete 2: has a mass of 55 kg and travelled at an average speed of 13.0 m/s against a force of 28N
- Athlete 3: has a mass of 68 kg and travelled at an average speed of 13.6 m/s against a force of 29N and won the race.
Make an assumption of constant speed and use the equation Power = (Force x Distance)/time to calculate the power output in W and then the power output in W/Kg. Which athlete falls under suspicion?
Students may find this interesting because the calculations throw suspicion on Athlete 2 even though he lost the race, because his power to weight ratio is over 6W/kg. These calculations can also be completed with the assistance of the British Cycling Federation PowerZone calculator [AR5]. This provides a more refined answer to the average power question.
In a resource downloadable from the Times Educational Supplement [AR4], uploaded by Eleanor Vickers, students are provided with six fact sheets on various athletes who have been caught doping. Divide the class into groups giving a fact sheet to each group – they use this to fill in their section on the summary table provided. Groups could then feed back to each other so that all the information is shared. There is then a card sort, giving certain opinions and perspectives on the use of drugs in sport.
Ask students to investigate reports of doping in the media. They should produce their own newspaper article, presentation or podcast on a particular sport or specific athlete. Examples you could suggest include athletics, which has recently been under scrutiny in the media, cycling, weight lifting, swimming and gymnastics.
[AR1] FITNESS STEP TEST HTTP://OW.LY/ST9RM
[AR2] METRONOME ONLINE HTTP://OW.LY/ST9LG
[AR3] CHROMATOGRAPHY OF LEAVES HTTP://OW.LY/ST9UJ
[AR4] CASE STUDIES ON DOPING HTTP://OW.LY/ST9YE
[AR5] BRITISH CYCLING POWERZONE CALCULATOR HTTP://OW.LY/STA3Y
ABOUT OUR EXPERT
Dr Joanna L. Rhodes M.Chem, D.Phil, MRSC is a teacher of science at Shelley College, Huddersfield.
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