Everybody wants to burn the most calories in the least amount of time, so it would be helpful to know which sports and recreational activities do the job. Here are 6 activities and the approximate number of calories they burn. Before launching into any of these activities, be sure to consult your doctor and always remember to warm up and stretch.

1. Rock Climbing:

Rock climbing relies on quick bursts of energy to get from one rock to the next. It won’t do a lot for your heart, but your strength, endurance and flexibility will greatly benefit, and you’ll burn about 371 calories every half hour.

2. Swimming:

Swimming provides an excellent overall body workout, burning up to 360 calories in a half hour depending on the stroke used. However, most people have difficulty maintaining proper form for that long. The best swim workout is based on interval training; swim two lengths, catch your breath and then repeat.

3. Cycling:

Cycling is an excellent non-weight-bearing exercise (meaning that your weight isn’t being supported by your body). Depending on your speed, it burns around 300 or 400 calories in a half hour. Cycling provides a great cardio workout and builds up those thighs and calves. However, it doesn’t provide much in the way of an upper body workout.

4. Rowing:

Burning about 280 calories per half hour, rowing is a very effective way to rid yourself of extra energy. It also builds up endurance, strength and muscle in your shoulders, thighs and biceps. The key to rowing is in the technique coordinate the legs, back and arms to work as one. Kayaking and canoeing each burn around 170 calories in a half hour.

5. Basketball:

The nonstop action of b-ball will see you dropping around 288 calories every half hour, while at the same time developing flexibility, endurance and cardio respiratory health. But warm up properly because the sudden twists and turns can be risky for the unprepared.

6. Boxing:

If you’re game enough to step into the ring, you’ll be rewarded with a 324-calorie deficit for every half hour of slugging it out boxing. In addition, your cardio respiratory fitness and muscular endurance will go through the roof. Make sure you’re match fit, though, or it may be all over before you build up a sweat!