Look no further — instead of squats, try this exercise to build explosive lower-body power and a stronger core

(Image credit: Shutterstock)

Three words: prisoner box jumps. You don’t need weights, just your body weight and a box or bench. If you have limited equipment or fancy skipping out squats for an effective alternative instead, this box jump variation is a beastly move that can build explosive lower-body power and improve core strength.

Plyometrics — think hopping-type motions — are used in functional training and by professional sportspeople and coaches to train the fast-twitch muscle fibers responsible for generating fast, explosive and powerful movements like jumping, weightlifting and sprinting.

Training the three muscle fiber types, especially your fast-twitch ones, will help you to withstand impact, make you a more robust exerciser and reduce your risk of injury as you age.

How to do prisoner box jumps

Prisoner box jumps combine the standard box jump with the set-up of a prisoner squat. Unfamiliar with both? Box jumps involve jumping from the ground onto a box, then extending your legs to stand up.

“Prisoner” simply means you’ll keep your hands behind your head throughout, pulling your elbows back to keep a proud and tall chest.

Prisoner Squat Box Jumps - YouTube

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Start with a box positioned in front of you at a height you feel comfortable with
Position your feet roughly shoulder-width apart, brace your core and lightly place your hands behind your head
Pull your elbows back and draw your shoulders together to open your chest. Keep your back straight
Softly bend your knees, then explosively jump onto the box, landing lightly with bent knees and both feet fully planted
Extend your legs fully to stand, then step down, one leg at a time. Your hands should remain behind your head throughout
You can perform a full squat before you jump onto the box, depending on your experience.

What are box jumps good for?

The muscular system contains muscle fibers known as slow-twitch and fast-twitch; slow-twitch fibers handle aerobic movement (motion that uses oxygen) to a certain degree of intensity, like endurance running, and fast-twitch muscle fibers take over as intensity increases and become anaerobic and more explosive (read: aerobic vs anaerobic training).

Fast-twitch fibers can be type IIA and IIB; think of IIA as a “transitional” in-between fiber type that can facilitate motion with and without oxygen (to a limit), whereas IIB requires no oxygen. Again, think short bursts of movement.

There’s plenty of research that exists examining the effectiveness of plyometrics for building muscular power. Plyometric training involves quick and powerful movements using stretch-shortening cycles (SSC) — pre-stretching a muscle and shortening it rapidly and repeatedly to create maximum force. This type of training therefore targets your fast-twitch muscle fibers to help you generate more power during movement.

What are prisoner squat box jumps good for?

A young woman preparing to do a box jump — (Image credit: Shutterstock)

Coupled with the box jump, prisoner squats target your lower body and core, including the glutes, hips, quads, hamstrings and calves. They also strengthen the hip, knee and ankle joints. Then, there's arm positioning, which improves posture and balance by testing upper-body postural and core stability while increasing engagement in the upper back.

Holding your hands behind your head will test your ability to sit tall without leaning forward or drawing your elbows together; this forces a fixed upright torso position, which can be incredibly difficult to maintain if you have poor shoulder or spinal mobility. As your technique improves, consider increasing the box height to make the box jump harder.

If you enjoy overhead exercises like the overhead press or squat, adopting the prisoner position will help you find more depth without compromising on your upper-body positioning, improving your stability and form.

However, if you’re still working on fixing up your squat technique, I wouldn’t start with prisoner squats or box jumps, as these are considered progressions. Instead, check out our guides on how to squat and ways to fix your butt wink (a common form mistake made while squatting) first.

The prisoner position also helps exercisers keep an eye on the positioning of their body overall, and where the limitations lie. It might feel frustrating at the time, but as you get stronger and your form improves, your box jump will only become more powerful.

Each time you lower your butt during the squat jumps, focus on sitting lower without your knees collapsing inward or heels lifting. Adding lower body mobility exercises and ankle stretches to your routine beforehand will also help you feel looser moving into box jumps, and I recommend trying a few sets of regular box jumps before adopting the prisoner position.

Bottom line

Plyometrics improves anything from explosive speed to jump height, muscle flexibility and impact-reaction (absorbing force through your body) making you a more resilient athlete capable of training in various planes of motion and environments. Over time, you may also build a better mind-muscle coordination, and boost power, mobility and stability.

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Sam Hopes is a level 3 qualified trainer, level 2 reiki practitioner and senior fitness writer at Tom's Guide. She is also currently undertaking her Yoga For Athletes training course. Sam has written for various fitness brands and websites over the years and has experience across brands at Future such as Live Science, Fit&Well, Coach, and T3.

Having worked with fitness studios like F45 and Virgin Active, Sam now primarily teaches outdoor bootcamps, bodyweight, calisthenics and kettlebells. She also coaches mobility and stretching-focused classes several times a week and believes that true strength comes from a holistic approach to training your body.

Sam has completed two mixed doubles Hyrox competitions in London and the Netherlands and finished her first doubles attempt in 1:11.