A “cell workout” uses bodyweight resistance training that can be done in a small space: 6ft x 8ft is more than enough. (I developed these exercises while in a cell at Pentonville prison.)

Glute kicker

Stand with your feet hip-width apart, back straight, head up. Jog on the spot, bringing your heels up behind you to touch your glutes, keeping your arms slightly bent. Continue, and increase the speed.

Power knee strike with twist

Stand with feet hip-width apart, arms extended straight overhead. Engage your abdominals. Place your weight behind one leg and bend the other knee, bringing that leg up and across your chest. At the same time, twist at the waist away from your raised leg, as you pull your arms across and down to the outside of it. Go back to the start position, tapping your toe on the floor, and repeat with the opposite leg.

Jumping cross jack

Stand with your feet out wide and your arms extended to form a star shape. Jump in, crossing one foot in front of the other, and cross your arms overhead. Continue, alternating left and right.

• LJ Flanders is the author of Cell Workout (cell-workout.com).