Jeffers is also high on kettlebell swings, something of a medieval-looking workout that really works your thighs and butt. "A 30-minute kettlebell workout, using the appropriate weight, can be as much, or more intensive, calorie burn-wise, than a 30-minute steady run," he says. "The shape of the weights requires increased stabilization strength in muscles around the joint in order to properly control them."
Metabolic resistance training
"Short spurts may seem easy, but when mapped out right, metabolic resistance training (MRT) can feel like running a marathon," warns Joni David-O’Connor, trainer at YG Studios. OK, maybe she's exaggerating a little. But metabolic resistance training -- a training style that aims to maximize caloric expenditure while increasing your metabolic rate, ideal for burning fat and building muscle -- is no jaunt in the park. "[MRT] pushes individuals to work as hard as possible in a variety of exercises for 15 to 20 seconds," she says. "The recovery times are close to a full minute, so you can give another all-out effort. I believe these small, explosive increments make difficult goals or exercise more attainable mentally."