Exercise guide
Alternating Hamstring Curl Jack
- Intermediate
- Compound
- Rep-based
- Lower legs
- Shoulders
- Upper legs
- Waist
This dynamic bodyweight exercise combines a hamstring curl with a chest-opening arm motion to improve cardiovascular endurance while engaging the core, hamstrings, and upper body. It serves as an effective low-impact alternative to traditional jumping jacks, emphasizing coordination and posterior chain activation.
Reviewed by the Crucible team · Updated June 2026
Muscles worked
Equipment
Setup
- Stand with your feet hip-width apart and your core braced.
- Extend your arms straight out in front of your chest at shoulder height, palms facing each other.
- Maintain a slight bend in your knees and keep your chest lifted.
How to do it
- Simultaneously pull your right heel toward your glute while swinging both arms out wide to your sides.
- Exhale as you squeeze your shoulder blades together and contract the hamstring of the curling leg.
- Inhale as you return your right foot to the floor and bring your hands back together in front of your chest.
- Immediately repeat the movement on the left side, alternating legs in a rhythmic, continuous tempo.
Form checklist
- Keep your torso upright; avoid leaning forward as you curl your leg.
- Ensure your knees point toward the floor during the curl to maximize hamstring contraction.
- Keep your core engaged to prevent your lower back from arching during the arm swing.
- Maintain a soft landing on the balls of your feet to protect your joints.
Pro tips
- Focus on the 'mind-muscle connection' by consciously squeezing your chest as your hands meet and your upper back as your arms open.
- Flex your foot (toes toward shin) during the curl to increase the intensity of the hamstring contraction.
- Keep your arms at shoulder height throughout the set to maintain constant tension on the deltoids.
Make it harder
- Increase the tempo to a light hop to transform the movement into a high-intensity plyometric exercise.
- Hold light dumbbells or wear ankle weights to increase resistance for the upper body and hamstrings.
Frequently asked
- What muscles does the alternating hamstring curl jack work?
- The alternating hamstring curl jack primarily targets the abs, glutes, hamstrings, and quadriceps, and also works the deltoids, erector spinae, hip flexors, and obliques as secondary muscles.
- What equipment do you need for the alternating hamstring curl jack?
- The alternating hamstring curl jack requires no equipment — just your body weight.
- Is the alternating hamstring curl jack good for beginners?
- The alternating hamstring curl jack is rated intermediate. Build a base with simpler variations first, then progress to it with light load and strict form.
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