You don't have to camp out on the treadmill to lose fat and keep your heart rate up. Several weight training methods will give you the same benefits, plus some bonus benefits for physique and strength development. Here's one of them.
The Active Rest Technique
This simple method consists of never taking actual rest periods during weight training. This means you include some light training or activity between the sets of each lifting exercise. This extra activity isn't so intense that it prevents you from performing at a high level in your actual lifting exercise; it's just enough to keep your heart rate elevated.
- Do the first set of your main exercise. Take no more than 15-20 seconds rest.
- Do active rest work for about 45-60 seconds. Take no more than 15-20 seconds rest.
- Do the second set of your main exercise.
- Continue in this manner.
What Exercises Can I Use?
- Ab work during upper body workouts.
- Postural exercises like band pull-aparts and rotator cuff exercises during lower body workouts.
- Ancillary hypertrophy exercises: Forearms, calves, etc.
Just make sure that the movement you select doesn't have a negative carryover to your main lift.