1. BURPEES
You burn around 1.43 calories per rep, says exercise scientist Jeff Godin.
Performing 10 reps at a fast pace can rev your metabolism as much as a 30-second, all-out bike sprint, according to a study presented at the American College of Sports Medicine’s annual meeting.
HOW TO DO IT
From a standing position squat down until your thighs are parallel to the floor and place your palms on the floor. From there kick your feet back as far as you can while keeping your arms extended. As soon as your feet land jump them back in towards your hands, then jump up into the air. Land and immediately squat down to go into the next rep. To up the difficulty, do a push-up at the bottom of the movement.
WORKOUT CHALLENGE
100 push-up burpees for time. Aim to finish in under 10 minutes.
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2. KETTLEBELL SWINGS
This is an explosive cardio exercise that works the big, powerful muscles around your glutes and quads, and sends your heart into overdrive, according to research from the University of Wisconsin.
In the study, participants burned 20.2 calories a minute and their average heart rate was 93% of its max for the course of a 20-minute workout.
HOW TO DO IT
Place a kettlebell a couple of feet in front of you. Stand with your feet slightly wider than shoulder-width apart and bend your knees to lean forward and grab the handle with both hands. With your back flat, engage your lats to pull the weight between your legs (be careful with how deep you swing) then drive your hips forward and explosively pull the kettlebell up to shoulder height with your arms straight in front of you. Return to the start position and repeat without pauses.
WORKOUT CHALLENGE
20 swings every minute, on the minute, for 10 minutes. This will hurt...
3. ROWING
You can burn 377 calories during 30 minutes of vigorous rowing, or about 12.5 calories per minute, reports a Harvard University study. And because you need to call on the muscles in your arms, legs, and back for efficient strokes, it's a total-body trainer.
HOW TO DO IT
Sit at a rowing machine with your feet fastened and grab the handle with an overhand grip. Straighten your legs to push the seat back – when your hands pass your knees, pull them up to your chest. Reverse the movement and repeat.
WORKOUT CHALLENGE
2km row for time. If you can finish under 8 minutes you're in good shape. Under 7 minutes and you're in peak shape.