Problem-Based Learning
Youth Olympic Games
Singapore Team SNOC Proposal
6/6/2010
Wecom Huang Hui Kang 3P324
Jonathan Phua Kia Sheng 3P308
Guan Ruofei 3P306


1. What is the sport you are presenting? What is the Physics behind the sport that forms the criteria for winning the event?

The sport that we are presenting is swimming, a very significant event at the Youth Olympic Games in Singapore. More specifically, the event is 100m freestyle swimming. This is a relatively short distance.

The Physics of Swimming

Density is mass divided by volume. Firstly, for a person to float on the water and not sink, his density must be less than the water’s density. Water has a density of 1g/cm3. When an object is less dense than water and thus floats, it is buoyant. Buoyancy is the tendency of an object to float on a liquid or rise in air or gas. The buoyancy of the person allows him to float on water. This buoyancy is partly contributed by the air in the person’s lungs. That is why, when a person drowns and inhales water into his lungs, the person becomes denser and sinks in water. You may ask why he will float to the surface later. That is because the rotting body swells as the body parts give off gases, and these increase the buoyancy of the person.

For a person to swim forward at a considerable speed in order to win the race, he must swing his arms and use his legs to push backwards against the water. Chemical energy from the food he consumed is converted to another form, kinetic energy. This produces a force against the water. According to Newton’s Third Law of Motion, each action force has an equal and opposite reaction force. Thus, the water pushes back with a force of equal magnitude on the person. This provides a force in the forward direction/the direction in which the person is swimming. If the force is greater in magnitude than the frictional force in water (also known as the water resistance force), then there is resultant force in the forward direction and the person moves forward/there is acceleration (due to F=ma). We ignore other forces (such as the normal force and the weight of the person) here as they are insignificant. Thus, to win the 100m freestyle event, the swimmer should have strong and muscular limbs to propel him in the water, gaining speed, which is what this event is about, how fast a person is underwater.

Talking about water resistance, it depends on two factors. Surface area is one of them. The larger the surface area of contact, the larger the water resistance force. This is because water resistance, like air resistance, are all types of friction, which is caused by the contact between two surfaces. Thus the swimmer should have a streamlined body shape, thereby reducing the force of water resistance. For a streamlined body shape, you can simply take a look at a dolphin or other fishes; their body shapes allow water to flow smoothly past the animals. Thus, it helps if the swimmer has a sharp head and is as streamlined as a human can get.

The other factor is the speed of the swimmer. The faster the swimmer underwater, the more water resistance he experiences. To understand this, picture yourself standing in the middle of the road. You don’t really feel much air resistance, unless there is wind or moving air of course. But when you get moving, you will feel more and more air resistance. If it is possible (probably not though) and you go really fast, the air resistance will soon be equal to your driving force produced by your legs. That is when you have no resultant force in the forward or backward direction, and acceleration is zero. This is due to Newton’s Second Law of Motion, F=ma. This is when terminal velocity is reached. For a swimmer who does not want too much water resistance, he can choose to swim slowly but he would surely lose the 100m freestyle event. Thus, a swimmer should aim to reach terminal velocity, if that is ever achievable.

Water pressure, can also be considered as an aspect of the physics of swimming. It is however, insignificant, most of the time. This is as people do not swim to great depths in 100m freestyle event. Water pressure is the pressure exerted by water, on the person if he is swimming. Pressure is force divided by area. The deeper the person is, the more water pressure he experiences as there is more water exerting force on him. For instance, on land, a person experiences atmospheric pressure equal to the pressure exerted by two elephants stacked on him! Also, the change of atmospheric pressure is responsible for blocked ears in aeroplanes. A low air pressure signals bad weather like storms and rain. When travelling down into an oceanic trench (eg. Marianas Trench 11km deep), the pressures get really high. Thus the submarine must be very strong so that it would not break down under the enormous water pressure. However, swimmers of the 100m event do not go deep down into the water and thus are safe. Water pressure thus does not form the criteria for winning the 100m freestyle event.

2. What kind of human physique that is needed to enhance the performance of the sport (Physics of the human body, which parts of the body are stressed and when trained properly will enhance performance?)?

Freestyle

When swimming in free style, we will definitely need to use our arms to push ourselves forward. Our arms push against the water. According to the Newton’s third law, the water thus gives our bodies a push (opposite and equal reaction force). This resultant force acting on the body allows it to move in the forward direction. Thus to enhance the performance of free style swimming, we will need to train our arm muscles. If the arm muscles are stronger and can produce more strength and thus more force, the reaction force of the water on us would be greater. According to Newton’s second law of motion, the greater the force, the larger the acceleration (F=ma).

This training of our arm muscles will also help to increase our arm girth. With a greater arm circumference, we can have a greater area of contact with water when we are pushing our arms against it. This enables the water to produce a greater opposing force on us which pushes us further and longer forward. When swimming in free style, we turn our arms. This causes our deltoid muscle (the muscle forming the rounded contour of the shoulder) to be stressed. Thus we also need to train our deltoid muscle so as to turn our arms faster.

As we turn and try to stay afloat on the water, we will also need to develop strong abdominal and back muscle to swim efficiently. In free style, we need to flip our feet, and keep our legs straight. To main in this position, we have to stress our leg and hip muscles. We must train our leg and hip muscles to increase our stamina during free style swimming. We need training to obtain a slim hip as this will reduce the opposing force (that acts against our forward movement) experienced when moving in water. As we are swimming, we need to take in enough oxygen so as to produce enough energy to swim fast. To achieve this, we need to have strong lung muscles and high lung capacity to take in lots of oxygen.

3. What training and diet enhancement you would recommend to improve performance?

Diet enhancement

The International Conference on Foods, Nutrition and Sports in Lausanne (1991) agreed the following nutrient intakes to be optimum for most sports: 60-70% of calories in the diet from carbohydrates, 12% from protein and the remainder (18-28%) from fat. This in effect means eating a diet far higher in carbohydrate and lower in fat and protein than average.

Carbohydrate, the first key ingredient

Carbohydrate is a crucial fuel for exercise. The body makes its own carbohydrate store, known as glycogen, which is stashed away in the liver and muscles. Glycogen is the body's fuel of choice for any exercise more intense than a gentle jog. This is because it can be broken down to provide energy more quickly than fat (the body's other major energy store). However, the snag with glycogen is that only limited amounts of it can be stored. This means that regular training, as well as competition where activity is at least an hour long, carries the risk of glycogen depletion. Low glycogen stores will mean a more sluggish performance and an increased risk of injury.

A guideline to aim for is 8-lOg carbohydrate per kg of body weight per day. For an average man (70kg), this would mean aiming for a daily intake of 560-700g; for an average woman (55kg), between 440-550g. Tips for boosting your carbo intake The twin strategies are to cut back on fat and to increase carbohydrates:

1 Base meals around carbohydrate foods - potatoes, pasta, rice, bread.

2 Eat smaller portions of fat-rich foods (eg meat, pies, cheese) and fill up with extra potatoes or bread.

3 Porridge made with water makes a high-carbohydrate start to the day.

4 Drink fruit juice with meals, and a milky drink at bedtime.

5 Cut bread extra-thick for sandwiches.

6 Try carbohydrate-rich snacks that are also low in fat: eg fresh or dried fruit, water biscuits spread with jam.

7 Choose pasta sauces based on tomatoes or vegetables rather than meat or cheese.

If the athlete need to replenish his/her glycogen stores quickly (eg they're training every one or two days) it's best to take advantage of the fact that the body is more likely to make glycogen immediately AFTER exercising - the sooner, the better. Some foods are better than others for this - the best are those with a high 'glycaemic index' (a term which means they will bring about a large surge in blood sugar). Examples of such foods are: bread (white or wholemeal), rice, potatoes, raisins, bananas, glucose, sucrose and honey. If they can't face eating straight after exercising, try a carbo-rich drink instead.

Fluid, the second key ingredient

For many athletes, dehydration is something to watch out for. Even moderate fluid losses can mean operating at less than 80% of your potential, and more significant losses could be dangerous to your health. To make sure that your fluid balance is well in the black before competing, drink more water than you usually would for the few days beforehand. Don't drink alcohol the night before an event - it will dehydrate you. Before competing, try to drink between 1/2 and 1/4 pint 15 minutes before the start.

Iron, the third key ingredient

Many athletes run the risk of low iron, partly because the stresses of their sport lead to increased losses of iron from the body (runners seem particularly susceptible). A number of studies have found that people in regular training and/or sports activity have low levels of ferritin, a body store of iron. People with low iron stores complain of tiredness and poor recovery from training. If the situation becomes worse, and haemoglobin (the form in which iron is transported around in the blood) levels fall, anaemia could result, with symptoms of severe fatigue, cramps, headaches and shortness of breath.

So what can you do if you suspect you're iron deficient? Iron supplements are available,and taking some for a few days to see if you notice any improvement could help identify if you really are deficient. However, supplements are commonly associated with side-effects such as nausea and heartburn, so your best bet is to try and boost your iron intake by dietary means. Even i-f you don't suffer immediate side-effects, you should seek medical advice before taking an iron supplement regularly, because it's also possible to suffer health problems from too much iron!

• Haem iron foods: liver, liver pate, lean steak, chicken (dark meat), fish, oysters, salmon

• Non-haem iron foods: eggs, breakfast cereal (fortified), wholemeal bread, spinach (cooked), lentils/kidney beans (cooked), tofu, sultanas, dried apricots, almonds, cocoa.

Haem iron is better absorbed by the body than nonhaem. However, absorption of non-haem iron is enhanced by vitamin C, so include some raw or lightly cooked vegetables with a meal, or drink fruit juice. Conversely, drinking tea or coffee will make the iron more difficult to absorb.

More Iron-> more Haemoglobin-> more red blood cells to carry oxygen to the muscles-> Increased Efficiency

Proteins, the third key ingredient

When proteins are digested, amino acids are absorbed into the bloodstream, enter the cells and used to build up different proteins:

• Proteins form part of the protoplasm of the new cells (during growth) and worn-out cells (during cell repair). Swimmers need to repair their worn out cells after training and before competition, to enhance the efficiency.

• Proteins help form heamoglobin in blood. With more proteins, more haemoglobin would be formed, and thus there will be more red blood cells, so there will be more RBC to transport the oxygen around the body, to the muscles during competition, which will eventually increase the athlete’s efficiency.

Proteins can be found in lean meat, fish, eggs, beans, peas and beancurd.

Avoid:

1) Food which contain too much fats.

Reason: Optimum body fat for swimmers has become controversial of late. Traditionally, swimmers tend to have more body fat than their counterparts in other sports such as running or cycling. This has always been considered to be an advantage because of the added buoyancy factor. However, recent research has thrown doubt on this accepted wisdom. A study at the University of Georgia found that more fat is not necessarily an advantage. In trials, extra body fat was found to decrease V02max (maximal aerobic capacity). Swimmers trying to lose fat should follow a diet which restricts calories by cutting down on fatty foods. Some popular weight-loss diets advocate cutting down on starchy foods - this is never recommended for an active sportsperson.