Sports Medicine

Reference Corner [PDF]
常見運動創傷 腳跟(阿基利斯跟腱)受傷
Achilles Tendon Rupture

What is Sports Medicine

Sports medicine is a science with knowledge integration of different specialties, including orthopaedics, cardiopulmonary medicine, sports psychology, physiotherapy, sports nutrition, sports training and Prosthetics and Orthotics. Through various researches on different sports-related issues, it aims to improve health and the quality of life.

The range of services provided by a sports medicine centre in the main covers:
  •  Treatment for sports injury
  • Rehabilitation after sports injury
  • Education on sports injury prevention
  • Training to enhance sports performance
  • Body-building of athletes
  • To deal with the psychological needs of athletes
  • Researches on sports performance
  • To treat and prevent illness through exercise
  • Diet and nutrition advice for athletes
  • Development of equipment and skills to enhance sports performance

Our Professionals
Our orthopaedic specialists manage musculoskeletal diseases or injuries of the limbs. Many surgeries can now be performed using endoscopes and minimally invasive technology, which induce less operative trauma. These less invasive surgeries include anterior cruciate ligament reconstruction of the knee and stabilization of shoulder joint for recurrent shoulder dislocation.

Prosthetics and Orthotics
Tailor-made appliances are provided by our prosthetist-orthotist to speed up the recovery of injured joints or muscles.

Our cardiologists can assess individuals their fitness for sports using different tests including non-invasive tests, like standard electrocardiogram, echocardiogram or exercise treadmill stress test.

Fitness assessment tests can be carried out by our physiotherapists to evaluate cardio-respiratory status, muscular endurance, flexibility and agility for individuals in designing an effective and safe exercise programme. Personal trainers will offer instructions and advice on proper exercise positions to enhance sports performance. Rehabilitation service is also provided.

Sports Nutrition
Our dietitians assess the nutritional status of individuals and provide dietary consultations. Diet suggestions will be given to help improve sports performance.

What is Sports Injury?
Sports injuries are injuries that occur to athletes during sporting activities. According to statistics, there are 250,000 cases of anterior cruciate ligament tears induced by sports in the United States every year. In Canada, there are 16,000 cases of sports injuries on young people aged from five to sixteen annually. Sports injury is also commonly seen in Hong Kong.

There are two major causes for sports injuries. The first is accidents, which are usually induced by a lack of knowledge, poor training or improper equipment. Second would be the overuse of certain parts of the body caused by insufficient warm up, lack of stretching exercises or prolonged exercises. Repetitive strain injury would occur if this persists.

Most sports injuries involve the musculoskeletal system, which includes skin, bones, cartilage, ligament, muscle and tendon. Severity of the injuries can vary from mild spraining to ligament tears or even fractures.

If you suffer an injury, immediate first aid measures help. One of the most important acronyms to remember is R.I.C.E, which stands for Rest, Ice, Compression and Elevation. Rest is vital to protect the injured body parts. You can apply Ice bags or cold packs to provide cold to the injured area for pain relief. It also limits swelling by reducing blood flow to the injured area. Compression limits swelling and provides pain relief. Elevation of the injured part reduces swelling as well.

Of course, you should always consult a doctor for thorough examination and proper treatment of the injury.

Common Sports-Related Injuries

Children's Sports Injuries
Sports injuries are not limited to adults only. Children also suffer from sports injuries.

Active children are prone to sports injury
Children of the age of 4 or 5 are generally active. They like to run, jump and generally be happy like they should be. Most of them like to play in the playground. But beware: children often sustain injuries whilst playing in the playground. They could injured themselves from playing with the seesaw or the swing. Falling off from monkey bars is notoriously a common injury and can cause fracture of the elbow and wrist in children.

See a doctor immediately when bone fractures are suspected.
Small in size and unaware of dangers while playing, children are easy victims to sports injuries. Their elbows are particularly vulnerable when they hit the ground. Forehead bruising and knee abrasion are also common among children. Parents should be alert at all times.

The children's skeletons are different from the adults' in ligament elasticity. Their ligament tissues are in general more elastic and flexible. Instead of ligaments, it is usually the bones that fail to withstand crushing upon contact and thereby fracture occurs.

Children may have fractured bones if their limbs are swollen or they are reluctant to move. Consult a doctor as soon as these telltale signs are seen.

Beware of Rugby Fingers
In most ball games, e.g. basketball and volleyball, the ball size is far larger than a child's hand in proportion. The forceful impact upon contact may cause fractures in the bones of fingers ("Rugby Finger"). Whenever they are hurt in the fingers during games, seek medical treatment immediately.

As a preventive measure, wrap their fingers with elastic and protective bandage before games.

Prevention is always better than cure
However advanced they might be, medical treatments and rehabilitation techniques are not as crucial as preventive measures to protecting the delicate musculoskeletal system of children. For better protection, make them wear protective gears like wristband, knee brace, bike helmet, etc. at games.

Types of Sports and Related Injuries

How to Prevent Sports Injury
Appropriate preventive actions should be taken before and after exercise. Continuous training is the best preventive measure against sports injuries.

Understand Your Health Condition
Knowing one's physical capability and limitations are of great importance to prevent sports injury. If the intensity of exercise is more than your body can take and you are not aware of it, you may end up risking your health or even your life. It is always good to have body checkup and physical fitness assessment before taking up any vigorous sports.

Know and Abide by the Rules of the Sport
Other than understanding your fitness level, you should also learn more about the sport you choose. As simple as jogging, there is also correct posture to be maintained and proper equipment to be used. Neglecting this may lead to strain and damage in muscles and joints.

Equipment and Location
It is very important to learn about the sports equipment and on-site safety. If you work out in a fitness centre but know nothing about the equipment, accidents may occur and you may be injured. For seasonal sports, such as skiing, you must choose a safe venue with good facilities and qualified trainers. Make sure there is proper first-aid equipment to cope with emergency situations.

Never Exhaust Yourself
Do not overdo exercise, especially when you are tired, as it will only affect your performance. The risk of injury is also greatly increased.

Below: First-aid equipment, such as defibrillator, enhances safety when one exercises.

Before and After Exercise
You should warm-up and cool-down respectively before and after exercise. It is a well known yet often neglected practice. Some people do not know how to do it properly. Since muscles, tendons and joints are rather stiff before exercise, warming up is to get them prepared for the activities later.

Warm-Up Exercise

Warm-up exercise should last around ten to fifteen minutes. Start with jogging or jumping to raise body temperature, enhance circulation and prepare your heart and lungs. You can also simulate the movement of passing a football, swinging a golf club, shooting a basketball, etc, so that your body and brain are prepared for the sport that you are going to play.


As your body temperature rises, you can start stretching the tendons in your neck, shoulders, back, waist, upper legs, lower legs and feet to improve their flexibility. Hold each stretch for ten seconds and relax. Repeat ten times. Do not overstretch. There should be a feeling of progressive relaxation. Stop if there is muscle pain or muscle tension as this may indicate overuse injuries.

Cool-down Exercise
Cooling down is similar to warming up, except that it should be done after exercise. While tendons get stiff and tired, cool-down exercise would allow them to relax, lowering the chances of cramps or overuse injuries.

Continuous Training
During exercise, you need to use muscles, joints, tendons and ligaments. It is important to maintain, through continuous practice, a good level of muscle power, endurance, flexibility, balance, coordination and agility. You may get hurt easily otherwise.

The intensity of the practice varies with each individual's purpose of exercise. Professional athletes may need daily training whilst amateurs can go for lower frequency and intensity if their purposes are merely for weight control, leisure or family activities.

Cardio-respiratory Endurance
Cardio-respiratory fitness is essential for all kinds of sports. Only with healthy circulatory system can one sustain prolonged exercise. Jogging, cycling and working out on an Arc Trainer are good ways to improve cardio-respiratory fitness. During exercise, you should try to maintain your heart rate in your target heart rate zone*. The exercise should also last for at least twenty minutes in order to boost your cardio-respiratory endurance.

* Target Heart Rate Zone: (220- your age) x 70% to 85%

Muscle Power & Endurance
One repetition maximum (1RM) is the maximum amount of weight one can lift in a single repetition for a given exercise. Different kinds of sports require different levels of muscle power. Racquet sports demands more on the arms, so players should focus on training the muscles in their shoulders and arms. On the other hand, ball games require more strength of lower limb, thus player should plan their trainings accordingly.

Muscle endurance is another factor to consider during exercise. Fatigue and pain of muscles can occur easily without good endurance. The risk of over straining will also increase. To prevent these, one should take up resistive exercise to enhance muscle power and endurance.


Every movement requires adequate control and coordination of different sets of muscles. Take racquet sports as an example, it requires a stable scapula for the shoulder to swing. Without it, you will be using a wrong amount of force that can easily lead to injury on bones and joints.

It takes regular practice to build up satisfactory muscle coordination. You should learn to better control your muscles in order to produce force and stabilize different parts of your body. Proper instructions and trainings should be given by physiotherapists or personal trainers.

Maintaining a good balance will reduce your risk of falling during exercise. This involves the sensory ability of the joints. When the brain receives information from the joints through the neurological system, your body will adjust its movement accordingly. So that when you trip over something, your feet will change position and help you stand steadily. This sensory ability is particularly important for skiing and other lower limb exercise, as players need to maintain balance whilst handling several movements within a few seconds. Fail in keeping the balance may cause severe injuries.


For some exercise, such as yoga and dance, it is required to have flexible muscles and tendons, as well as a certain range of motion in the joints. Strains or sprains will occur if the range is low. To increase the flexibility, you should do more stretching and rotation exercise.

The ability to move rapidly and make efficient change of direction is crucial to certain sports. To jump, stop and make a turn in an instance requires an integration of isolated movement skills with a combination of balance, coordination, speed, reflexes, strength, endurance and stamina.

Equipment & Training

To enhance sports performance, prevent sports injury and promote recovery after injury, it is crucial to have comprehensive equipment, adequate facilities and appropriate training programmes. Our Department of Physiotherapy is thereby ready to offer tailor-made treatment plans in the following areas:

Physical fitness assessment:
With the advanced equipment we conduct fitness assessment tests for you before you start doing exercise. The results will be used to design a training programme that suits you the best.

Training programme:
Through tailor-made training programmes, you can make use of fitness equipment and facilitate to enhance your performance inn sports.

Physical fitness assessment before exercise
  1. Aerobic Fitness
    VO2 max is the maximum capacity of an individual's body to transport and utilize oxygen during incremental exercise, which reflects the physical fitness of the individual. The name is derived from V - volume per time, O2 - oxygen, max - maximum. Measuring the VO2 max is said to be the most direct and accurate method to assess the status of cardio-pulmonary system. A healthy cardiopulmonary system is a strong back up for different sports.

    VO2 max Test
    During the test, you will be asked to jog on a treadmill for 15 minutes. The speed will then be adjusted gradually every 2 to 3 minutes, from moderate to maximal intensity, until your heart rate reaches 70% to 85% of your maximum heart rate. The results will be generated by an oxygen analyzer.

  2. Muscle Power and Endurance
    It is important to know your maximum muscle power and endurance for a certain exercise. Training below the limits will help to prevent muscle fatigue and injuries whilst at the same time slowly enhance sports performance.

    One Repetition Maximum Tests (1-RM Tests)
    The purpose of this test is to measure the maximum strength of various muscles and muscle groups. After a warm up, choose a weight that is achievable. Then after a rest of at least several minutes, increase the weight and try again. You will be asked to lift subsequent weights until you can only repeat one full and correct lift of that weight. That will be the maximum strength of the muscle group tested.

    Hand Grip Test
    The purpose of this test is to measure grip or forearm muscle strength. Handgrip strength is important for any sport in which the hands are used for catching, throwing or lifting.

  3. Flexibility Test
    Flexibility is the capacity of a joint to move through its full range of motion. Knowing it will prevent you from over-stretching. Specific exercise can also be done to improve the flexibility of particular joints.

    Sit and Reach Test

    It measures the flexibility of the lower back and hamstring muscles. Lower back pain is often suffered by those who do not have sufficient degree of flexibility in these muscles.

    A Goniometer is used to measure the range of motion of a joint, which is important for avoiding over stretching of muscles and joints.

  4. Anthropometric Measurement
    This measurement helps you to understand your own physical body built. You can therefore choose a sport that is suitable for you to improve your health.

    Body Mass Index (BMI)
    This index calculates the proportion of weight and height, i.e. kg/ m2. It reflects your body status and predicts the chance of suffering from certain diseases. For Asian population, a BMI over 23 is defined as overweight and a BMI over 25 as obese.

    Waist Circumference
    A male adult with a waist circumference of 35 inches (90 cm) and a female adult with a waist circumference of 31 inches (80cm) are considered having Central Obesity. This greatly increases the risk of getting type II diabetes, cardiovascular disease and diseases related to high blood pressure.

Training Programme

Aerobic Training
Treadmills, elliptical trainers and arc trainers are some of the equipment you can use for aerobic training, during which you can improve aerobic capacity and enhance aerobic endurance.

Muscle Training

Muscle power and endurance can be enhanced through resistance training using fitness equipment. Coordination training needs specially designed programmes that are instructed by physiotherapist. An optimal performance of the muscles can thus be ensured.

Flexibility Training
Stretching, contraction and relaxation exercises can improve muscle flexibility. Exercise balls can also be used during flexibility training.

The root of hydrotherapy can be traced back to ancient Greece. Today, it is widely adopted in the area of Physiotherapy due to the following advantages:
Pain Relief
A hydrotherapy pool with water temperature ranging from 32°C to 34°C is optimal. Patients will feel warm and comfortable. The buoyancy and water massage can also relieve pain of the injured joints and limbs.

Weight Training
The amount of weight a human body can carry varies in different depths of water. Making use of this and arrange weight training underwater will help patients speed up the recovery process from bone fractures and ligament tears.

Strengthening of Muscles
The buoyancy, turbulence and resistive nature of water are three efficient characteristics used to strengthen muscles and to enhance bodily function It is specifically beneficial for deep abdominal and balance training. It is particularly good for trunk core muscle and balance training.

Underwater Camera

This camera allows us to observe the movement of patients underwater. Therapists can thereby give appropriate instructions and monitor the progress of patients. Training process is also recorded to assess treatment outcomes.

Exercise-Related Disease
Appropriate exercise can help improve heart and lung functions and reduce chronic diseases, but incidents of exercise-related heart attack and sudden death published in the media have made people puzzle about the benefit of exercise, especially when some cases involved young healthy people.


Exercise-related heart disease
Human bodies demand greater supply of oxygen during exercise. This demand has to be supported by a healthy heart and a normal blood circulation. People who are physically fit with strong heart muscles can handle exercise of different intensity. With sufficient preparations and comprehensive preventive measures, exercise is always safe and beneficial.

The abrupt onset of disease and sudden death during exercise usually happen to people with silent heart disease or cardiopulmonary problems, of which Hypertrophic Cardiomyopathy and Coronary Heart Disease are the most dominant.

Hypertrophic cardiomyopathy is a disease of the myocardium (the muscle of the heart) in which a portion of it is hypertrophied (thickened) without any obvious cause. As the muscle is located where the heart connects with the aorta, it will obstruct the outflow of blood and chaotic heart rhythm is common. The condition is particularly severe during exercise when the blood circulation is intense. On the other hand, patient suffering from Coronary Heart Disease with narrow and blocked coronary arteries also have difficulty circulating blood. Since the heart needs to pump quicker and strongly in order to meet the oxygen demand, the patient may feel severe chest pain or distress if the blood supplied to the heart muscle is compromised. People with these two conditions should not exercise too long at a time, otherwise the exhausted heart muscles and the lack of blood oxygen may lead to heart attack or even sudden death.

Who should have health screening?
Knowing one's own condition and limitation will help a person to avoid doing more exercise than one can physically handle. Unfortunately, very often people may not have symptom at all. Health screening thereby plays an important role in minimizing the risk of exercise-related disease and sudden death.

People should have heart health screening under the following circumstances:
  • A family history of heart disease
  • Chest tightness, dizziness and shortness of breathe during exercise
  • Diabetes, high cholesterol, high blood pressure, habit of smoking, obesity
  • A history of drug abuse (e.g. cocaine)
  • Liquid protein, diet that may cause life-threatening heart rhythm
  • Long-term exercise planned, e.g. marathon/ triathlon runner
Exercise Electrocardiogram (ECG) and ultrasound examination of the heart are two good ways to assess the condition of the heart. To carry out an Exercise ECG test, one will be asked to run on a treadmill with an ECG machine connected to the body. In this case, the electrical activity of the heart will be measured. On the other hand, a heart ultrasound is a test that uses high-frequency sound waves to create images of the heart from multiple angles. Structure and functions of the heart can thereby be assesses clearly.

Exercise properly
Those with no heart disease can do exercise as they wish, such as aerobic training that enhances one's cardio-pulmonary functions or resistance training that strengthens one's muscles. However, it is important to do exercise of an appropriate intensity, which can be determined by one's maximum heart rate. Do note that one can suffer from fatigue or injury if over-exercise, yet an insufficient intensity will fail to serve the intended purpose of exercise. Thus a balance between the two should be maintained.

Those with heart disease can also do exercise, as long as they have recovered from treatment. Instructed by medical personnel, they can do an appropriate amount of exercise with the right intensity. Even after angioplasty or bypass surgery, patients can still carry out aerobic training, such as swimming and brisk walking, which can help strengthening and restoring the cardio-pulmonary functions. However, weight-lifting and other resistance training should be done only after proper assessment.

Exercise-related Asthma
Exercise-related asthma is commonly seen among children and teenagers. The attack is induced after several minutes of intense exercise, usually in people who do not experience asthma under any other circumstances. The symptoms start to show after continuous intense exercise or labouring, but these will disappear if the person continues to exercise for more than an hour.

During intense exercise, one not only breathes through the nose but also the mouth. If the air that hits the lungs is colder and drier, the contrast between the warm air in the lungs and the cold inhaled air can trigger an attack. Once the attack is triggered, the airways begin to swell and secrete large amounts of mucus. One will then experience the symptoms of asthma, such as coughing, chest distress, wheezing and fatigue. If the air inhaled is polluted or contains allergen, inflammation of the airway may occur, which can be serious and even life-threatening. This is especially true for those who have asthma attacks other than during exercise.

How to avoid symptoms of Asthma?
A Spirometry test can be arranged by a doctor for those who have exercise-related asthma. Most cases can be treated by medication such as Salbutamol. Another option would be controlling the duration of exercise.

Since the symptoms of asthma start to show after several minutes of intense exercise and tend to disappear after an hour, one can try to improve the situation with a longer warm-up session. This not only allows one's body to gradually adapt to the intensity of exercise, but also makes it possible for the asthma to be induced earlier. Once it happens, one can take a rest immediately thus better the symptoms after the exercise begins.

Exercise-related Anaphylaxis
Food-dependent, exercise-related anaphylaxis occurs only when an individual eats a specific food AND exercises within a short while afterwards. The symptoms include shortness of breath, cramps, collapse and unconsciousness.

The food allergens can be seafood, butter or cheese etc. One may not normally have allergic response to the food, but the anaphylaxis is likely to be induced when the food is ingested right before exercise. It is actually a very rare condition, but when one suffers from exercise-related conditions that are not related to heart functions or asthma, it can be the underlying cause.

Exercise and Nutrition
During exercise, the body needs various nutrients to generate energy. There are six major classes of nutrients in food, namely, carbohydrate, protein, fat, vitamin, mineral and water. The former three provide energy for exercise whilst the latter three enhance people's use of nutrition.

What does the body need during exercise?
Whether one can exercise continuously with satisfactory performance depends largely on the amount and type of nutrients one consumes. The exact requirements of various nutrients are conditioned by the intensity of exercise, age, gender, health condition, nutrient reserve, and the way one utilizes nutrition.

There is a sequence of how the body utilize nutrition. The first six seconds of exercise requires explosive force of muscles. During this period in which quick energy is needed, the body mainly derives energy from the ATP-CP energy system. Weight lifting, relying entirely on this system, is a great example of the kind of exercise that needs explosive force.

However, the ATP-CP system can only provide energy in short term. From 6 to 30 seconds after exercise, the body has to utilize carbohydrate as the fuel to support muscular movement under an anaerobic environment. Aerobic oxidation only begins from 30 seconds to 2 minutes after exercise, during which carbohydrate and fat are broken down. More carbohydrate is needed initially, but a larger amount of fat will be used after 30 minutes.

Whether the body burns carbohydrate or fat depends on both the intensity and duration of exercise. In other words, the more intense the exercise, the more proportion of carbohydrate will be burnt. On the other hand, the longer the duration of exercise, the more proportion of fat will be burnt.

Carbohydrate storage enhances sports performance
Glycogen, the carbohydrate stored in the muscles and livers of human body, is the main source of energy during exercise. Glucose is derived from it to provide energy during exercise. Normally, muscle glycogen can sustain 60 to 90 minutes of any medium to high intensity exercise, such as a 15 km long run. After that, glucose will be derived from liver glycogen instead to provide energy, and to be delivered in the form of blood glucose. If the amount of carbohydrate in diet is insufficient, there will be a lack of muscle and liver glycogen. One's endurance and performance during exercise will be greatly affected under such circumstance.

Daily carbohydrate intake for a normal person should amount to 45% to 65% of total energy consumed, whilst for athletes it should be around 60% to 70%. Prolonged exercise of medium to high intensity level may use up all glycogen in the body. A study indicates that increased carbohydrate consumption 3 to 4 days before exercise can help increase the storage of liver glycogen, thus enhancing the usage of energy during exercise. However, there is no extra storage needed for ordinary exercise that takes less than an hour.

The amount of carbohydrate to be stored should be calculated base on body weight. One should consume 7 to 10 grams of carbohydrate everyday per each kilogram of body weight. Endurance athlete who weights 50 kg should consume a total of 350 grams of carbohydrate everyday, which equals to:
  • 4 bowls or rice or noodles
  • 4 fruits
  • 2 glasses of milk or yoghurt
  • 1 bottle of sports drink
  • 2 bowls of cooked vegetables
  • optimum amount of meat

Continuous supply during exercise
For prolonged exercise, adequate carbohydrate intake is essential to supplement for the consumption. With carbohydrate, not only physical fitness can be maintained, sports injury can also be reduced as muscle fatigue is less likely to happen.

When doing exercise, the body needs about 35 to 45 grams of carbohydrate every hour, which amounts to 560 to 750 ml of sports drink. This applies to medium and high intensity level of exercise, such as long run, basketball and football etc. A meal with high glycemic index (GI) foods or drinks during exercise will also help increase blood glucose, thus energy can be obtained by muscles more quickly.
Diet with high glycemic index after exercise
The storage of carbohydrate has to be replenished when it is used up, especially for athletes who may have competitions one day after another.

To regain stamina and energy, one should intake 0.7 to 1.5 gram of carbohydrate per kilogram of body mass, which amounts to about one and a half bottle of sports drink. The most efficient time to consume would be within half an hour after exercise. Thereafter, the same amount of carbohydrate should be consumed every 2 hours until 6 hours after exercise.

Fat is the main energy fuel during endurance exercise. The longer the exercise duration, the more fat will be burnt. When fat loss is the target for exercise, prolonged aerobic exercise of low to medium intensity would be the right choice. The body uses fat as the main energy source when one's heart rate is maintained within 40% to 70% of the maximum heart rate. As the intensity increases, the body will use more carbohydrate instead. For instance, although both will cover a distance of 6 km, brisk walking at 6 km per hour for 60 minutes will burn more fat than running at 12 km per hour for 30 minutes.

More over, studies have shown that athletes or those who exercise regularly have more fat burning enzymes in blood, meaning that their muscles tend to burn more fats compared to others.. However, unlike carbohydrates, the amount of fat burnt is not proportional to the amount of fat consumed or stored. Since fat utilization is controlled by hormones, it is not necessary to increase the fat consumption to promote fat utilization during exercise. The optimum amount of fat consumption would be 15% to 30% of the total calories consumed daily.

Protein can also provide energy, but it is not the main energy source for exercise. In fact, only about 5 % of the energy during exercise are from protein. Only when both carbohydrate and fat are used up would the body break down protein as energy. Therefore, an increase in protein intake will not directly enhance sports performance. Yet it is still important to consume enough protein in order to maintain a normal muscle mass.

In general, people's daily need for protein is 0.8 gram per each kilogram of body weight. On the other hand, athletes need 1.2 to1.4 grams per each kilogram of body weight whilst bodybuilders need up to 1.8 gram per kilogram of body weight. 

Vitamin and Mineral
Vitamins usually function in the body as coenzymes, especially the Vitamin B complex that helps carry nutrition. As a result, carbohydrate can be utilized more efficiently by the body. As for minerals, they are essential to maintain muscle function, bone health and nutrient transmission.

One's physical functions will be affected if the body is deficient in vitamins and minerals, this will definitely affect sports performance. A well-balanced diet should be able to provide enough vitamins and minerals and there is no need to take additional nutrition supplements.

Sufficient fluid ensures one's body to function properly, and helps maintain normal chemical reaction in the body during exercise. Not only does fluid enhance one's performance in endurance sports, but also facilitate efficient utilization of carbohydrate and fat. Human body loses huge amount fluid during exercise. Thirst occurs when 1% of fluid is lost. When more than 2% of fluid is lost, one will feel tired and have dry . With 5% of fluid loss, one's physical fitness may even be reduced by 50%. Therefore, fluid is very critical to sports performance.

Basically, healthy individuals is advised to take 1 millilitre of fluid per each calorie consumed. Therefore, athletes should consume between 2000 to 4000 millilitres of fluid, and an additional amount is required during exercise. For example one should intake 600 millilitres of fluid an hour before exercise and 150 to 300 millilitres every 15 to 20 minutes during exercise. During hot weather, the amount should also be increased. After exercise, one should replenish 450 to 675 millilitre of fluid for every pound of fluid lost, indicated by body weight.

In normal circumstance, drinking water should be sufficient during exercise. But in prolonged and intensive exercise, one can consider using sports drinks to replenish carbohydrate, fluid and electrolytes at the same time. Suitable sports drinks often contain 6 to 8% of carbohydrate, i.e. 6 to 8 grams of carbohydrate in every 100 millilitre fluid, for optimal absorption.

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