I'm a personal trainer and I've been using this routine to build functional core strength for over 20 years

For all the one-minute-abs routines and muscle-zapping electromagnetic (EMS) classes I've tried, there is one bodyweight routine that I've always stuck with for core strength.

I first started using this workout in my late teens, and it's still doing the trick for me and my clients more than two decades later.

The circuit combines three classics: the abdominal crunch, plank tuck and reverse plank.

It incorporates core flexion, extension, static holds and unilateral elements—which work one side of the body at a time to challenge the abdominal muscles' ability to resist rotation.

The third move (reverse plank) also targets the core muscles' role within the lower back of the posterior chain for a 360˚ approach to abs training.

Combined, these exercises should provide a solid foundation of core strength, which will keep your body strong and robust as you age.

How to do the workout

Perform all exercises back-to-back for one round.

• Abs crunch with feet down x10
• Abs crunch from tabletop x10
• Abs crunch with straight legs x10
• Plank with knee to corresponding elbow x10 each side
• Plank with knee to opposite elbow x10 each side
• Spiderman push-up (optional) x5-10 each side
• Reverse plank x30-45 secs
• Reverse plank with marches (optional) x30-45 secs

1. Abs crunch

Do the following group of exercises back to back before moving onto the next group.

1A. Abs crunch with feet down

Set: 1 Reps: 10

• Lie on your back with knees bent and feet flat on the floor.
• Straighten and raise your arms so that your hands point towards your knees.
• Keeping your back pressed into the floor, use your abs to lift your head and shoulders off the floor. Your hands should lift towards your knees.
• Lower and repeat.

1B. Abs crunch from table top

Set: 1 Reps: 10

• Lie down on your back.
• Bend your knees to 90° and lift your legs, so that your lower leg is parallel to the floor.
• Straighten and raise your arms so they point towards your knees.
• Keeping your lower back pressed into the floor, engage your abs and lift your shoulders and head off the floor.
• Lower and repeat.

1C. Abs crunch with straight legs

Set: 1 Reps 10

• Lie down with legs straight.
• Lift your legs so that they're pointing upwards.
• Straighten and raise your arms so they're pointing towards your knees.
• Keeping your back pressed into the floor, engage your abs and lift your shoulders and head off the floor.
• Lower back down and repeat.

The abdominal crunch might get a bad rap in fitness circles, but it's the ultimate functional core exercise. Think about it: how do you get out of bed, off the sofa or off the floor? By engaging your abs to sit up.

Try to breathe normally throughout this 30 rep sequence, moving slow and steady, and focusing on using your abs to initiate the movement rather than craning your neck.

2. Long Plank

Next is the plank exercises with straight arms, starting as if in a push-up position. If this is a challenge in itself, hold this stance for 30-45 seconds. Rest for 15 seconds or so between exercises.

2A. Long plank knee to elbow

Set: 1 Reps: 10 each side

• Come onto your hands and knees, with your hands placed under your shoulders and your knees in line with your hips.
• Step your legs back so that your body forms a straight line from your shoulders to your heels.
• Bend your right knee and bring it up to meet your right elbow.
• Step your foot back and repeat on the opposite side.

2B. Long plank knee to opposite elbow

Set: 1 Reps: 10 each side

• Come onto your hands and knees, with your hands placed under your shoulders and your knees in line with your hips.
• Step your legs back so that your body forms a straight line from your shoulders to your heels.
• Bend your right knee and cross it under your body to meet your left elbow.
• Step your foot back and repeat on the opposite side.

2C. Spider-Man push-up (optional)

Set: 1 Reps 5-10 each side

• Come onto your hands and knees, with your hands placed just wide of your shoulders and your knees in line with your hips.
• Step your legs back so that your body forms a straight line from your shoulders to your heels. This is the classic push-up position.
• Bend your elbows and lower your chest to the floor.
• As you do this, bend one knee out to the side and bring it up to meet your elbow on the same side of the body.
• Push back up and repeat on the other side.

3. Reverse Plank

3A. Reverse plank

Set: 1 Time: 30-45 seconds

• Sit on the floor with your legs bent, feet flat on the floor.
• Straighten your arms and put your hands on the floor behind you, fingers pointing forward towards your feet.
• Step your feet out and push your hips up, resting on your heels. Your body should form a straight line from your shoulders, hips and ankles are aligned.
• Engage your glutes, hamstrings and lower back to maintain a solid position.

3B. Reverse plank marches (optional)

Set: 1 Reps: 30-45 seconds

• Sit on the floor with your legs bent, feet flat on the floor.
• Straighten your arms and put your hands on the floor just behind you, fingers pointing forward towards your feet.
• Step your feet out and push your hips up, resting on your heels. Your body should form a straight line from your shoulders, hips and ankles are aligned.
• Engage your glutes, hamstrings and lower back to maintain a solid position.
• With control, bend your knee and bring it up towards your chest.