Quick Answer
Side Jackknife is a beginner strength exercise that targets your obliques and abdominals. It uses only your bodyweight. Lie right side, legs stacked.
Video Tutorial
How to Perform the Side Jackknife
- 1
Lie right side, legs stacked.
- 2
Right arm floor support, left hand behind head.
- 3
Lift legs and torso simultaneously.
- 4
Bring left elbow towards left knee.
- 5
Squeeze obliques.
- 6
Lower slowly.
- 7
Repeat reps, switch sides.
Common Mistakes to Avoid
- !Rushing reps instead of controlling the lowering (eccentric) phase — aim for 2–3 seconds down.
- !Letting form break down as reps add up. Stop the set when technique slips, not when you physically can't do another rep.
- !Using momentum to swing through reps. Pause briefly in the contracted position to keep tension on the muscle.
Tips for Better Form
- ✓Breathe out during the effort (concentric) and breathe in on the return (eccentric).
- ✓Use a mirror or film yourself on your first session — your perceived form and actual form often differ.
- ✓Keep ribs down and lats engaged — this keeps tension on the core, not the hip flexors.
- ✓Don't worry about load — master the movement pattern with light weight or easier variations first.
Alternative Exercises
If the Side Jackknife isn't right for your body, equipment, or goal, try these similar exercises that hit the same muscle groups:
Frequently Asked Questions
What muscles does the Side Jackknife work?
The Side Jackknife primarily works your obliques and abdominals. Secondary muscles include the hip flexors and core.
What equipment do I need for the Side Jackknife?
The Side Jackknife needs no equipment — just your bodyweight. You can perform it at home or at the gym as long as you have what's listed.
Is the Side Jackknife suitable for beginners?
Yes. The Side Jackknife is a beginner-level exercise. Start with lighter load or fewer reps and focus on form before adding intensity.
How many sets and reps of Side Jackknife should I do?
For strength: 3–5 sets of 3–6 reps with longer rest (2–3 min). For hypertrophy (muscle growth): 3–4 sets of 8–12 reps with moderate rest (60–90 sec). For endurance: 2–3 sets of 15+ reps with short rest (30–45 sec). Adjust based on your program and goal.
Can I do the Side Jackknife every day?
No. Muscles need 48 hours to recover between heavy training sessions. If you want to train obliques and abdominals more frequently, alternate harder and easier variations and keep overall weekly volume moderate.