Experts recommend that teens be moderately active for 30 minutes every day, or almost every day in addition to being vigorously active for at least 20 minutes or more at least three times a week.
How many of us follow these recommendations? And why is it important for us to be active?
The 2001 Hong Kong Youth Fitness Study which looked at the physical activity levels of over 2,220 secondary school students found that 18.3 per cent led sedentary lifestyles.
Less than a third were active enough to benefit their health.
Regular exercise has countless health benefits such as reducing the risk of heart disease in later life.
Heart disease is the second largest cause of death in Hong Kong. High levels of 'bad' cholesterol and stress are two factors which increase our chances of developing heart disease.
Research has shown that exercise has positive effects on our levels of 'good' cholesterol as well as stress.
Exercise and 'good' cholesterol
A 2007 review of 25 scientific studies looking at the relationship between exercise and levels of good cholesterol in the body found that individuals who are more physically active have higher levels of good cholesterol.
The minimum amount of exercise needed to improve levels of good cholesterol was 120 minutes per week.
The review also found that duration of exercise was more important than frequency and intensity.
So, in terms of improving good cholesterol levels, it appears to be better if we exercise for longer at each session rather than doing multiple short sessions.
Exercise and stress
A study by the University of Missouri found that vigorous exercise seems to be more effective at reducing stress and anxiety, especially among women.
The study measured the levels of anxiety in female volunteers before and after they completed 30 minutes of either moderate or intense exercise. Their anxiety levels were measured again at five, 30, 60 and 90 minutes after the exercise session.
Levels of anxiety were lowest in those volunteers who took part in the high intensity exercise sessions. The benefits weren't immediately seen - stress levels dropped 30, 60 and 90 minutes after exercising.
What types of exercise are beneficial?
According to the Health First Study conducted by the University of Alberta, Canada, slow walking doesn't give any health benefits because it's a low intensity activity.
Researchers tested two groups over six months. One group was asked to walk 10,000 steps each day and the other was asked to exercise at moderate intensity using treadmills and stationary bicycles.
Results showed that the fitness and blood pressure levels of the group exercising at moderate intensity levels improved more than those who took part in the walking programme.
The researchers concluded that while the 10,000 steps programme is good as a starting point for most people, it's important to more towards regular moderate to vigorous exercise to achieve health benefits.
What does this mean for me?
These studies show that to prevent heart disease in later life, you be physically active for at least half an hour every day.
Choose aerobic activities that make your heart and lungs stronger whenever you can, for example, fast walking, swimming, bicycling, hiking, basketball and football.
If you like walking as an activity, walk at a faster pace uphill or go hiking.
How active are you?
How often do you exercise?
a. I don't exercise
b. Once or twice a week
c. Three or four times
d. Five or more times a week
How much time do you spend being active each day?
a. 0-10 minutes
b. 10-20 minutes
c. 20-30 minutes
d. 30 minutes or more
When you're active, which of the following applies to you
a. I don't exercise
b. I can breathe and talk normally
c. I breathe faster than normal
d. I am out of breath and sweaty
Mostly a's - Couch Potato: You need to think about building some activity into your normal routine as your health is your wealth. Start with gentle exercises, such as walking, and then gradually build up to fast walking over a period of a few weeks. You'll really feel the difference in your energy levels and health.
Mostly b's: - Slow but sure: You're doing some exercise during the day, which is good, but try and build in some more sessions each week and aim for a mixture of low, moderate and vigorous intensity exercises in your sessions.
Mostly c's: - Almost there: To benefit from all the advantages of exercise, you just need to do a little bit more. Keep your motivation up by including activities that you really enjoy, eg. dancing, hiking, skating or swimming.
Mostly d's: - Well done: You're reached those exercise targets. Carry on with the good work and try and build in at least three sessions of vigorous activities each week e.g. running, football or basketball.