This is the term we use to categorise our strength-training machines.
They typically comprise of a pin and stack configuration where a pin is used to select one or more plates from a weight stack, thereby increasing or reducing the total weight lifted.
Contrary to popular opinion, resistance machines can be used to burn just as many calories as cardio-based machines.
The main difference is how and when the calories are burned ...
With resistance machines, the body's muscles are put under stress, typically one group at a time.
In scientific terms, this is called Anaerobic training as opposed to Aerobic (or cardio-based) training.
Heart rate, body temperature and breathing should all be slightly elevated during a weight training session, but the body doesn't burn calories as rapidly as it does during a cardio-based training routine.
Because of this, a common misconception is that cardio-based workouts burn more calories than weights-based workouts.
The reality is that both types of workout can consume just as many calories, just not in the same time-frame.
With a cardio-based routine, the vast majority of calories are burned during the workout, with the body's metabolism returning back to normal levels soon after the routine has been completed.
During an anaerobic or weights-based routine, the body continues to burn calories at an accelerated rate for several hours after the workout.
So, whilst less calories are burned during the workout, the proceeding recovery phase (which can last up to 6 or so hours), results in the body consuming calories at an accelerated rate as it begins the body's repair and recovery phase (for the specific muscles that were trained).
The net result is almost as many calories burned by both workouts, with the added advantage that a weights-based routine will slowly build your muscle density over time, meaning you become a more efficient fat-burning machine, quite simply because you're building a bigger engine that requires more fuel to power it through the day.