Side Jackknife
A beginner compound movement that trains the abdominals with just bodyweight.
Force Type
Pull
direction of effort
Difficulty
Beginner
training level
Variations
0
equipment swaps
Muscles
1
primary + secondary
Side Jackknife vs every catalogued exercise by instruction-text length
Where this record's instruction-character count sits among all 873 Free Exercise DB exercises with instructions, not a rating of the movement itself.
2 869th of 873 the lowest of 873 exercises
All exercises, banded by instruction-text character count
Each bar is a band; taller bars hold more exercises. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count and share, and where it sits relative to this entry.
Source Free Exercise DB · 2026-07-10
Side Jackknife is documented from the Free Exercise DB (CC0) extract, last ingested July 2026. Classification, muscle roles and instruction text are source facts; the placement and cohort measures on this page are computed by PlainExercise and are not a rating of the movement.
What the Side Jackknife Data Reveals · THIN · PULL/COMPOUND
Side Jackknife stands out on instruction depth: step count is the binding differentiator before muscle mix.
A short step list is a thin upstream record, so taxonomy badges carry most of the page identity.
Context matters: taxonomy (level, mechanic, force, musculature, equipment) does not account for individual biomechanics, joint history, or recovery. Common-mistake framing below is derived from classification fields, not case-specific coaching. Not medical or personal-training advice. Consult a physician or certified trainer before starting, especially with injuries, cardiovascular conditions, recent surgery, or pregnancy.
Side Jackknife catalog footprint
Among 93 exercises whose primary muscle is abdominals, Side Jackknife ranks #12 by catalogued variation count. The upstream file attaches 2 images to this slug. See the step-count ranking for abdominals for peer documentation depth.
Muscles worked
The Free Exercise DB classifies each muscle as primary or secondary. It does not measure activation, so we show involvement, not percentages.
Source: Free Exercise DB primary/secondary muscle classification. Actual recruitment varies by load and form.
Intensity context
For reference, here is where common activities sit on the MET intensity scale. Side Jackknife does not have a measured MET in the source data, its intensity depends on the load and effort you use. Estimate calories for any activity with the calorie calculator.
MET values from the Compendium of Physical Activities (Ainsworth et al., 2011). A general reference scale, not a rating of this specific movement.
Common mistakes
- Rushing through reps before the pattern is grooved - at this stage, a slow, controlled tempo (2-3s down, 1-2s up) on Side Jackknife teaches the nervous system the movement far faster than speed does.
- Cutting the range of motion short - moving the abdominals through its full safe range on Side Jackknife is what most reliably separates effective reps from wasted ones.
- Treating a compound lift like an isolation movement - Side Jackknife recruits multiple joints; bracing the core and engaging stabilizers matters as much as the prime movers.
- Shrugging the shoulders up toward the ears on pull movements, keep shoulder blades down and back to load the correct muscles.
- Breathing out of sync with the lift on Side Jackknife - brace and inhale during the lowering phase, exhale on the exertion, especially important with just bodyweight where control matters most.
Who this is for
- People new to resistance training who want to build a foundation in the movement pattern
- People who want to train the Abdominals
- People training at home without equipment
Who this is NOT for
- People hunting equipment swaps, this record has none to offer; browse the peer abdominals exercises for alternate patterns instead.
- Anyone with acute pain in the joints or muscles involved, pain is a stop signal, not a soreness signal
- People with unresolved injuries in the loaded joints, seek clearance from a physical therapist first
- Anyone with a recent surgery, cardiovascular limitation, or pregnancy complication without physician clearance
Progression path
Once Side Jackknife feels comfortable with your current load, progress by (a) adding reps until you can complete 12+ per set, (b) increasing resistance by 2.5-5%, (c) moving to harder variations such as single-limb or longer lever versions, and eventually (d) stepping up to intermediate-level movements that train the same muscle.
See the Progression guide for a full framework on when to advance, and the Compound vs Isolation guide to decide when to prioritize this movement in your program.
Safety notes · BODY-ONLY · PULL/COMPOUND · FLOOR
- On PULL/COMPOUND abdominals work, warm up 5–10 minutes before loading Side Jackknife; keep first sets light until the path feels automatic.
- Sharp or joint pain is a stop signal. Muscle soreness during sets is normal; pain is not.
- Beginners on BODY-ONLY gear: cut volume before cutting form, drop a set rather than rush reps.
- General information only. Consult a physician or certified trainer before starting any new exercise program.
Curated workout appearances
Side Jackknife is not currently featured in one of the 186 curated workout routines on this site.
Related exercises
Other exercises that target the Abdominals.
See all Abdominals exercises.
Using the side jackknife
Three ways to put it to work.
- Train the abdominals 2–3 times a week with 48+ hours between hard sets; pair this with other abdominals movements for balanced development. All abdominals exercises
- Match the load and rep range to your goal, strength, size, or endurance each call for a different scheme. Strength vs hypertrophy
- As a compound lift, this trains several muscles at once, anchor your session around it before isolation work. Compound vs isolation
Form before load. If a movement causes sharp or joint pain, stop and substitute a safer alternative, this is general information, not medical or training advice.