Abdominals
Jackknife Sit-Up
A bodyweight ab exercise where you raise your arms and legs together to meet over your hips in a V shape.
Primary musclesAbdominals
Energy burned
≈ 17 kcalFor 3 × 8–12, rest 90s · ≈ 2.9 kcal/min
Estimate range 12–21 kcal (±25 %)
Muscle mass worked4 %
Effort during a set4.5 MET
Your lean mass53.5 kgBody fat estimated from BMI and age
Body-weight exercise: your whole body is the load, so heavier people burn more.
Estimate ±25 %: muscles worked (from the exercise data), sets, reps, rest and your body. See the planner for whole sessions.
Setup
- 1Lie flat on your back with your legs extended and your arms stretched overhead.
- 2Brace your core and press your lower back toward the floor.
How to perform
- 1Lift your arms and legs at the same time, bringing your torso up off the floor.
- 2Reach your hands toward your feet as your legs rise toward your chest.
- 3Squeeze your abs at the top of the V.
- 4Lower your arms and legs under control and repeat.
