This workout maximises reps, giving multiple muscle groups a boost in little time, says Tony Gentilcore, a strength coach at Cressey Performance in the US. Start with 5 reps each of the first two exercises and do them back-to-back with no rest. Break for 1 minute and repeat 2 or 3 times. Then do 6 reps each of the last two exercises and repeat them without resting until your 15 minutes are up.
1 BARBELL DEADLIFT
With your feet shoulder-width apart, bend and lift the bar with an overhand grip. Use your thighs and back to pull the weight up, keeping your shoulders and elbows locked, and your back flat. Slowly lower the weight.
Hang from a bar using a shoulder-width, underhand grip, with knees slightly bent and ankles crossed. Pull yourself up quickly until your chest touches the bar. If you have trouble, switch to a pull-down machine and use the same grip.
Assume a push-up position (hands slightly wider than shoulder-width apart, your body in a straight line from ankles to neck). Quickly lower yourself until your chest touches the floor and forcefully thrust yourself up. Too easy? Balance a weight plate on your back.
4 DUMBBELL LUNGE
Stand with your feet hip-width apart, holding dumbbells at your sides. Step forward with one leg and lower your body until the other knee nearly hits the floor. Quickly push back up, switch legs and repeat.