One of the more recent fitness fads is that of “unstable training,” with the idea that this accelerates the fat-burning process.
Have you noticed over the past several years the increasing prevalence of personal trainers having overweight clients doing all sorts of balancing stunts while lifting weights? It’s highly unlikely that these clients want to improve their balancing skills on one leg or with both legs on a shaky surface while lifting weights.
Like the majority of overweight men and women who strength train, they’d like to lose body fat. Same for the men and women who strength train on their own, but have jumped on this bandwagon of unstable device training.
Though standing on one leg while doing nothing with your upper body burns more calories than standing on both legs and doing nothing else, this simple fact does not carry over to strength training.
Strength training is a stellar way to burn fat, and does so via more than one pathway. One of those pathways is by increasing lean muscle tissue. The more lean muscle you have, the faster will be your resting metabolism.
In order to increase lean mass, you must keep increasing the amount of resistance over time; this is called progressive overload. When the muscle cells adapt (i.e., the exercise loses its difficulty), you add more resistance, to keep muscle fibers stimulated. This translates to a simple formula: More muscle = greater fat-burning.
How do you get more lean, shapely muscle?
Progressive overload; you lift as heavy as you can for a repetition range of about 8-12. This range provides sufficient time that the muscle fibers are under tension, which forces the innards of the muscle fiber to acquire more “metabolic machinery.”
The result is a more efficient, stronger muscle fiber that requires more fuel to operate. This fuel comes from stored body fat. In short, the more you can lift with time under tension, the more fat you will burn via more metabolic machinery.
Adding balancing to strength training interferes with progressive overload.
Imagine the heaviest dumbbells you can press overhead for 8-12 reps while standing on the floor. Now, imagine you’re standing on air cushions or the round side of a BOSU ball. Can you press the same amount of weight for 8-12 reps—or at all?
Combining balancing with strength training impairs ability to lift maximal loads, which interferes with progressive overload. You may think that adding balancing to strength training works more muscles and thus burns more calories. More muscles (small stabilizers) may get worked, but the net result is that the larger muscles (which naturally burn more fuel) can’t move as much weight, due to the detraction of the balancing.
A study (Appalachian State in North Carolina) showed that unstable squatting is inferior to stable squatting in terms of maximizing muscle activity.
If you want to burn fat with strength training, the no-gimmicky approach of the basics will be far more effective than trying to move resistance while standing on one leg or on a wobbly surface.