Physical Exercise

Exercise and Keep Fit

Exercise Tips for Children and Adolescents

Edited by Department of Sports Science and Physical Education, The Chinese University of Hong Kong and Student Health Service, Department of Health

Table of Content

  • Benefits of exercise
  • Some rules of exercise
  • Different types of exercise
  • Home exercise programme
  • Sports injury
  • Roles of parents
  • Energy expenditure in various types of physical activity

Benefits of exercise

Unless coupled with regular exercise, dieting alone does not have a long-lasting effect on weight loss. In fact, there are many benefits of exercise.

  • Improve heart and lung function
  • Build muscle and strengthen bones
  • Strengthen joints and improve flexibility, reducing the risk of injury
  • Speed up metabolism, burn calories and prevent accumulation of fat
  • Feel better, work better and cope with stress better
  • Boost immune system
  • Reduce the risk of developing heart diseases, hypertension and diabetes in adulthood

Some rules of exercise

  • Choose exercise according to your age and ability
  • Be persistent and patient
  • Exercise with friends or family members
  • Get into the habit of doing exercise
  • Incorporate exercise into your daily life, e.g. brisk-walking, stair-climbing, etc.

Different types of exercise

(A) Warm-up exercises

  • Warm up for about 10 minutes before vigorous exercise
  • Increase heart rate and body temperature, increase blood circulation
  • Improve body awareness and reflexes
  • Increase flexibility and lower the risk of injury
  • Prepare your body for vigorous exercise
  • Warm-up exercise can be divided into two categories:
    • 1. Gentle exercise
    • 2. Stretching exercise

1. Gentle Exercise

  • Straighten your arms and do arm circles.
  • Arms akimbo, lift up your foot alternately.
  • Walk on the spot, raise your leg until your thigh is parallel to the ground.
  • Raise your arms upwards and do split jump. Hands down and return to standing.
  • Slight bend your knees. Stretch and straighten your arms backwards. Swing your arms upwards and jump.
  • Run on the spot 10 times.

2. Stretching Exercise

An exercise that helps improve flexibility and reduce the risk of strain and sprain.

Points to note:

  • Ensure a correct starting position
  • Gradually increase the intensity of stretching
  • Stretch your tight muscles for 10 to 15 seconds and relax your muscles slowly
  • Avoid jump movements during stretching
  • Breathe naturally during stretching
  • Repeat each movement 2 to 3 times
  • Do stretching exercise 3 to 7 times a week

Preparation stance: stand with your feet shoulder-width apart

  • (a) Stretching exercise for head
          Arms akimbo, then:
    1. Tilt your head to the left, count to 10. Return to the starting position.
    2. Tilt your head to the right, count to 10. Return to the starting position.
    3. Turn your head to the left, count to 10. Return to the starting position.
    4. Turn your head to the right, count to 10. Return to the starting position.
  • (b) Stretching exercise for upper limbs
    1. Triceps
      Straighten your right arm sideways to the left. Cross your left elbow over your right arm and pull your right arm towards yourself. Count to 10 and then repeat on the other side.
    2. Chest muscle
      Stand straight, straighten your arms and put both arms behind your back. Lift your arms slowly. Count to 10. Return to the starting position.
  • (c) Stretching exercise for back and abdomen
          Arms akimbo and then:
    1. Twist your upper body to the left. Count to 10. Return to the starting position.
    2. Twist your upper body to the right. Count to 10. Return to the starting position.
    3. Raise your right arm with your left arm akimbo. Bend your upper body to the left. Count to 10. Return to the starting position.
    4. Raise your left arm with your right arm akimbo. Bend your upper body to the right. Count to 10. Return to the starting position.
    5. Bend your body backwards with your arms akimbo. Count to 10. Return to the starting position.
  • (d) Stretching exercise for waist and back
  1. (1) Side waist
    • Exercise 1
      Stand with your legs slightly apart. Raise your right arm with your left arm akimbo. Bend your upper body to the left. Count to 10 and then repeat on the other side.
    • Exercise 2
      Sit on the floor and straighten your left leg. Bend your right leg and cross your right foot over your left leg. Use your right hand to support your body and twist your body to your right. Count to 10 and then repeat on the other side.
  2. (2) Back
    • Exercise 1
      Lie on the floor. Bend your knees and pull your legs towards your chest with both hands. Swing your body back and forth. Count to 10.
    • Exercise 2
      Kneel down and lie prone on the floor. Extend your arms forwards. Count to 10.
  • (e) Stretching exercise for lower limbs
  1. (1) Calf muscles
    • Stand and face the wall with both hands pressing against the wall. Step forward with your left foot with your knee bent. Right foot slide backward and extend. Count to 10. Repeat on the other side.
  2. (2) Inner thigh muscles
    • Sit on the floor. Bend your knees and bring your feet towards your pelvis with the soles of your feet touching each other. Use both hands to hold your feet. Count to 10.
  3. (3) Outer thigh muscles
    • Sit on the floor, straighten your left leg, bend your right knee, bend your upper body forward and try to reach your left knee with your forehead. Count to 10. Alternating between your two legs.
  4. (4) Quadriceps
    • Lie on your right side with your head resting in your right hand. Use your left hand to pull your left foot towards your hip. Count to 10. Alternating between your two legs.

(B) Aerobic exercises

Oxidative metabolism is the main source of energy for aerobic exercises. The exercises usually last for more than 5 minutes and are of moderate to vigorous intensity. They can strengthen heart and lung function, increase endurance and are especially effective in reducing the accumulation of body fat.

Children and adolescents may choose aerobic exercises according to their interest, age and ability e.g. running, cycling, swimming, dancing, ball games, etc.

The ideal level of exercise is determined by the ideal range of heart rate during exercise. The calculation is as follows:

  • The ideal range of heart rate　＝
                    (50% of the maximum reserved heart rate + resting heart rate)
                                                              to
                    (85% of the maximum reserved heart rate + resting heart rate)
  • Maximum reserved heart rate = Maximum heart rate一resting heart rate
  • Children and adolescentsmaximum heart rate = 200
  • Resting heart rate can be measured after resting for 15 minutes by counting the number of times the heart beats per minute

Physical fitness of children and adolescents varies between individuals. You may refer to the chart below to design different training programmes for your child.
A training programme can be divided into three stages :-

  • Early Stage –

1st week :

Exercise 3 times per week. The level of exercise should be 40 to 50% of the maximum reserved heart rate. The exercise should last for 12 minutes.

2nd week :

Exercise 3 times per week. The level of exercise should be 50% of the maximum reserved heart rate. The exercise should last for 14 minutes.

3rd week :

Exercise 3 times per week. The level of exercise should be 60% of the maximum reserved heart rate. The exercise should last for 16 minutes.

4th week :

Exercise 3 times per week. The level of exercise should be 60 to 70% of the maximum reserved heart rate. The exercise should last for 18 minutes

5th week :

Exercise 3 times per week. The level of exercise should be 60 to 70% of the maximum reserved heart rate. The exercise should last for 20 minutes.
  • Training Stage –

6th to 9th week :

Exercise 3 to 4 times per week. The level of exercise should be 70 to 80% of the maximum reserved heart rate. The exercise should last for 21 minutes.

10th to 13th week :

Exercise 3 to 4 times per week. The level of exercise should be 70 to 80% of the maximum reserved heart rate. The exercise should last for 24 minutes.

14th to 16th week :

Exercise 3 to 4 times per week. The level of exercise should be 70 to 80% of the maximum reserved heart rate. The exercise should last for 24 minutes.

17th to 19th week :

Exercise 4 to 5 times per week. The level of exercise should be 70 to 80% of the maximum reserved heart rate. The exercise should last for 28 minutes.

20th to 23rd week :

Exercise 4 to 5 times per week. The level of exercise should be 70 to 80% of the maximum reserved heart rate. The exercise should last for 30 minutes.

24th to 27th week :

Exercise 4 to 5 times per week. The level of exercise should be 70 to 85% of the maximum reserved heart rate. The exercise should last for 30 minutes.
  • Maintenance Stage –

28th week and above :

Exercise 3 times per week. The level of exercise should be 70 to 85% of the maximum reserved heart rate. The exercise should last for 30 to 45 minutes.
  • ＊Apart from the training programme mentioned above, children and adolescents should accumulate at least one hour of moderate- to vigorous-intensity physical activity daily.

(C) Muscle–building exercises

  • Improve muscle strength and endurance
  • No additional equipment is required
  • Do the exercise 3 times a week. Repeat each movement 10 to 25 times according to your ability. Do the whole set of movement 3 times

Examples of muscle-building exercises

  1. Lower limbs
    • Stair climbing
    • Stand against the wall and slightly bend your knees as if you are sitting on a chair
    • Kneel with your hands on the floor, then raise one leg until it is parallel to the floor, alternating between two legs
  2. Back
    Lie prone on the floor, then lift your shoulders and arms off of the ground without using your arms to help
  3. Abdomen
    Sit-ups: lie on the floor, bend your knees, cross your arms in front of your chest and lift your head and shoulders until your shoulder blades are not touching the floor
  4. Upper limbs
    Do push-ups with your knees on the floor. If you cannot do this movement, you may stand up and do wall push-ups

(D) Cool-down exercises

  • Do after main exercise for about 10 minutes
  • Allow organs and systems in body to cool down slowly
  • Enhance the blood supply to muscles, help remove metabolic waste due to exercises, so that muscles recover faster
  • Movements are similar to that of warm-up exercises except to gradually decrease the speed and range of movements. Movements include walking on the spot, walking, deep breathing, stretching exercise, etc.

Home Exercise Programme

Examples of home exercise programme : -

  • 1) Every Monday, Wednesday, Friday
    • 10 minutes warm-up exercises / stretching exercises
    • 20 to 30 minutes aerobic exercises (improve heart and lung function)
    • 10 minutes cool-down exercises
  • 2) Every Tuesday, Thursday, Saturday
    • 10 minutes warm-up exercises / stretching exercises
    • 20 to 30 minutes muscle-building exercises
    • 10 minutes cool-down exercises
  • 3) Every Sunday
    • 10 minutes warm-up exercises
    • 20 to 30 minutes exercises for better balance and eye-hand coordination and quicker response
      (Parents should encourage their child to participate in outdoor activities and non-competitive sports such as dancing, skipping and cycling. This will prevent him/her from giving up too easily due to a fear of failure. It would be better if parents can also participate in these activities)
    • 10 minutes cool-down exercises

Sports Injury

  • 1. Common sports injuries among children and adolescents
    • Abrasions and bruises
    • Strain in muscles and ligaments
    • Muscle cramps
    • Sprained joints
    • Low back pain
    • Heat stroke
    • Head injury
  • 2. Safety tips
    • Consult your physician before sports training, especially if you suffer from a medical condition e.g. heart disease, asthma, etc.
    • Parentsor teachersguidance during exercise is important to ensure safety
    • Always do warm-up and cool-down before and after exercise to lower the risk of strain and sprain
    • Wear appropriate, comfortable clothing and cushioned footwear to support your heel and arches
    • Wear protective gear during exercise e.g. wear a cycle helmet and knee pads for cycling, and a life jacket for water sports like canoeing, windsurfing, etc.
    • Do not exercise immediately on a full stomach
    • Beware of the weather and environmental conditions. Avoid doing vigorous exercises in extremely hot or humid weather
    • Whatever the physical activity you choose, exercise regularly and progressively according to your own ability. Never expect to see much progress after exercising several times only
    • Do not exercise if you feel unwell
    • Stop exercising and take a rest if you feel breathless, dizzy, or nauseous
    • Do not make dangerous movements that may harm yourself or others
  • 3. Management of sports injury
    • Keep calm and inform your parents or teachers immediately if accident happens
    • Parents and teachers should learn first aid and teach elder children some simple ways to cope in accidents
    • Clean the wound with clean water and dress it with a sterile adhesive bandage or sterile gauze to prevent further injuries
    • Seek medical advice whenever necessary

Roles of parents

Parents influence their children in many ways throughout their lives. It is important for parents to set good role-models by actively participating in different kinds of physical activities.

Notes to parents

  • Encourage your child to try various kinds of sports e.g. cycling, swimming, etc.
  • Arrange outdoor activities with family on weekends or holidays e.g. hiking, picnicking, swimming, etc.
  • Exercise with your child for fun and giving support
  • Share your childs feelings and give appropriate advice

Energy expenditure in various types of physical activity

In order to stay healthy, we must adopt a healthy diet and exercise regularly at an early age. To prevent obesity in children and adolescents, it is important to balance energy intake and expenditure through diet and exercise.

  • The unit for energy expenditure is calorie (1000 calories = 1 kilocalorie)
  • Energy expenditure differs between different activities
    e.g. for a child weighing 45kg, a 30-minute skipping will expend 0.162 kilocalories/min/kg x 30 minutes x 45kg = 219 kilocalories
Type of physical activity

Energy
expenditure
(kilocalories/min/kg) 		Energy expended by a 45 kg child performing this activity for 30 minutes (kilocalories)

Sitting

0.021

28

Knitting, Sewing

0.023

31

Card game

0.023

31

Standing

0.028

38

Writing

0.030

41

Playing piano

0.040

54

Playing violin

0.047

63

Canoeing

0.047

63

Doing housework

0.062

86

Gymnastics

0.064

86

Table-tennis

0.068

92

Walking

0.083

112

Bowling

0.094

127

Badminton

0.098

132

Tennis

0.109

147

Roller-skating

0.113

153

Free style swimming

0.128

173

Running on flat ground (run 4 laps around a football field, equivalent to 1.6 kilometres, in 11 minutes)

0.134

181

Basketball

0.138

186

Marching

0.143

193

Breaststroke swimming

0.162

219

Skipping

0.162

219

Running on flat ground (run 4 laps around a football field, equivalent to 1.6 kilometres, in 9 minutes)

0.194

262

Judo

0.196

265

(Revised in June 2022)

 

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