If you want to burn more calories then the treadmill is the machine for you. A recent test carried out at Dublin University researchers studied the burn ratio with gym cardio vascular machines. This test result showed that running on the treadmill was the best way to burn fat efficiently.

Using the gym machines the test measured which machine burn't the most calories in the shortest time.

Results show how long it would take to burn on average 200 calories 

1. 14 minutes - Treadmill
2. 16 minutes - X trainer
3. 21 minutes - Rower
4. 29 minutes - Cycling bike

The reason why the Treadmill came in first position is because of the exercise. When we run we activate and use more of our muscles during the exercise and we use our body weight for resistance.  These increase the body burn rate.

The other gym machines normally support our body weight and use less muscles in the movement. This support produces less body weight and therefor we burn less calories.