It’s the final five that never want to budge. That’s why we tapped celebrity trainer Harley Pasternak for research-backed ways to blast through a weight-loss plateau once and for all.

Reason to add a sandbag to your workout: People who exercised with one had higher heart rates and thus likely burned more calories than those who did the same moves with dumbbells, new research from the University of Wisconsin–Milwaukee finds. That’s because sand is unpredictable; it moves, so you have to work harder to stabilize the load than if you held something solid, the study authors explain.

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Seizing the fat-sizzling opportunity, Equinox launched Elimin8tor, a new class that uses SandBells (round, sand-filled neoprene bags), at locations nationwide. It involves doing challenging rounds of SandBell moves, like drags, slams, and plyos. We asked class creator Dana McCaw to develop a routine based on Elimin8tor, so you can try the hot new workout on your own. “You’ll start with the longest, hardest 8-minute round of moves, then pare down as you go,” she explains. “When you reach those last two rounds, they feel easy in comparison.”