Time to get physical
Abby asks: What sort of exercise is best for people my age?
Wynnie says: We all know that exercise is good for us. Being physically fit means you have the energy and strength to cope with everyday life - from listening attentively during classroom lessons and doing your homework effectively, to taking an active part in PE lessons and hanging out with friends.
To be physically fit, there are three areas we need to work on: cardiovascular fitness, muscle strength and flexibility.
Cardiovascular exercises help us do physical work for a long time without getting tired. They include any activity that gets the heart pumping and the muscles using oxygen.
Teens should exercise for an hour every day, and the American Heart Association suggests that teens give their hearts a good workout for 20 minutes without stopping, at least three times a week. By doing this regularly, your heart will become stronger and better at supplying oxygen to every part of your body.
Cardiovascular or aerobic (which means 'with air') exercise not only improves heart function but also helps lower blood pressure, increase 'good' cholesterol, lowers 'bad' blood cholesterol and reduce body fat.
Aerobic exercises include running, skating, swimming, brisk walking, tennis, basketball, dancing, kickboxing, hockey, football, rowing, handball, skiing and skipping.
The heart and other muscles benefit from exercise, too. Strength training is all about building muscle, and the more muscle you have, the more calories you burn. Muscle strength means that you can lift and move heavy things.
Different types of strength training builds different muscle groups. For example, push-ups, pull-ups and rowing are useful for strengthening the muscles in your arms. Running, cycling, skiing and walking are good for strengthening leg muscles, whilst crunches and sit-ups are great for toning and tightening tummy muscles.
It's best to do these activities in sets of repetitions, e.g. start with one set of eight sit-ups and work your way up to three sets of 12 sit-ups. This will improve muscle strength and endurance.
Don't be tempted to do any form of weight or power lifting to try to 'bulk up'. Your body is still growing, and these types of activities can cause injuries to developing muscles, bones and joints.
Being flexible means your muscles and joints can bend, move, twist and stretch without strain or pain. Great stretching or flexibility exercises include yoga, Pilates, ballet, tai chi, front or side stretches, dancing, skating and gymnastics. Stretching regularly is a sure way to improve your flexibility.
Breakfast: Macaroni with ham and bacon
Lunch: Cup noodles at school or beef bowl at Yoshinoya
Dinner: Rice, soup, lettuce and pork, beef or chicken dishes at home
Snack: Candy and potato chips from the snack bar at school
Exercises: Cycling twice a month and hiking once a month