Exercise guide · Intermediate · Compound

Exercise Ball Back Extension with Knees Off Ground: How to Do It & Muscles Worked

This exercise targets the spinal erectors and requires you to perform a back extension while balancing your hips on a stability ball with your knees off the ground. It challenges your core, glutes, and hamstrings, and requires balance and coordination.

Primary muscles
Not recorded
Secondary muscles
Hamstrings , Glutes
Equipment
Stability Ball
Level · type
Intermediate · Compound
Demonstration of the exercise ball back extension with knees off ground
Front view: muscles worked by the exercise ball back extension with knees off ground. Secondary: hamstrings and glutes.
Back view: muscles worked by the exercise ball back extension with knees off ground. Secondary: hamstrings and glutes.
Primary Secondary

How to do the exercise ball back extension with knees off ground

  1. Step 1: Place the stability ball on the ground and lie face down on top of it, with your hips resting on the ball and your feet against a wall for stability.
  2. Step 2: Position your hands behind your head or crossed over your chest.
  3. Step 3: Engage your core and slowly lift your upper body off the ball, extending your back until your body forms a straight line from your head to your heels.
  4. Step 4: Pause for a moment at the top, then slowly lower your upper body back down to the starting position.
  5. Step 5: Repeat for the desired number of repetitions.

Sets, reps and programming

Suggested sets, reps and rest for the exercise ball back extension with knees off ground by training goal
Goal Sets Reps Rest Effort
Strength 3–5 3–6 3–5 min 1–3 reps in reserve
Muscle growth 3–4 6–12 2–3 min 1–2 reps in reserve
Muscular endurance 2–3 12–20 1–2 min 1–3 reps in reserve

Ranges follow the ACSM position stand on progression in resistance training. Muscle grows across a wide range of loads when sets end close to failure (Schoenfeld et al., 2017), longer rests between heavy sets support strength and size (Schoenfeld et al., 2016), and stopping a rep or two short of failure works about as well as training to failure (Grgic et al., 2022). Estimate your working weights with the strength calculators.

Sources

  1. American College of Sports Medicine. Progression models in resistance training for healthy adults. Med Sci Sports Exerc. 2009;41(3):687-708.
  2. Schoenfeld BJ, Grgic J, Ogborn D, Krieger JW. Strength and hypertrophy adaptations between low- vs. high-load resistance training. J Strength Cond Res. 2017;31(12):3508-3523.
  3. Schoenfeld BJ, Pope ZK, Benik FM, et al. Longer interset rest periods enhance muscle strength and hypertrophy in resistance-trained men. J Strength Cond Res. 2016;30(7):1805-1812.
  4. Grgic J, Schoenfeld BJ, Orazem J, Sabol F. Effects of resistance training performed to repetition failure or non-failure on muscular strength and hypertrophy: a systematic review and meta-analysis. J Sport Health Sci. 2022;11(2):202-211.

Step-by-step instructions and demonstration media are from the ExerciseDB exercise dataset.

This guide is general fitness information, not medical advice. Stop if an exercise causes pain and speak to a doctor or physiotherapist about injuries or health conditions before starting a new programme.