Knee Touch Crunch

beginner strength exercise · body weight · targets abs

Body part: waist
Primary target: abs
Equipment: body weight
Difficulty: beginner

The knee touch crunch is a beginner ab exercise that combines a crunch with a leg lift, with the goal of touching the knees with the hands at the top of each rep. The body folds slightly at the top — knees coming up to meet the upper body, hands reaching to the knees. The combination loads upper and lower abs simultaneously without the difficulty of full V-ups or jackknife sit-ups. It's a useful intermediate exercise between basic crunches (only upper-ab work) and more demanding combined exercises like jackknife sit-ups. Most beginners who can do 15+ standard crunches can manage 12-15 knee touch crunches in their first attempts. The combined movement is more efficient than separate exercises while remaining accessible to most fitness levels. Like all combined ab exercises, the trade-off is moderate intensity per area. The knee touch crunch loads neither the upper nor the lower abs as heavily as their dedicated exercises do. For maximum strength in either area, separate exercises are more effective. For general fitness, time-efficient training, and beginners, however, knee touch crunches earn their place.

Why train the Knee Touch Crunch?

Trains upper and lower abs simultaneously in one efficient movement.
More accessible than V-ups or jackknife sit-ups.
Time-saving for shorter workouts.
Easier on the lower back than full sit-ups.
Pairs well with planks for complete core training.
Requires no equipment.

How to do the Knee Touch Crunch: step by step

1Lie flat on your back with your knees bent and feet flat on the ground.
2Place your hands behind your head with your elbows pointing outwards.
3Engaging your abs, lift your shoulder blades off the ground and reach your right hand towards your left knee.
4Return to the starting position and repeat, this time reaching your left hand towards your right knee.
5Continue alternating sides for the desired number of repetitions.

Muscles worked

Primary

abs

Secondary

hip flexors

Common mistakes to avoid

Using momentum to swing the body together
Whipping the limbs together uses momentum and skips the actual ab work. Move slowly: 1-2 seconds together, brief pause at the top, 2-3 seconds back.
Letting the lower back arch off the floor at the bottom
Press the lower back into the floor throughout. If a hand could slide between back and floor, you've lost core engagement.
Pulling on the neck with the hands
Reach the hands toward the knees — don't yank the head forward. Keep the neck in line with the spine.
Cutting depth on the knee lift
The knees should come fully up to meet the hands. Half-hearted knee lifts skip the lower-ab work.
Holding the breath
Exhale on the contraction, inhale on the descent. Continuous breathing supports better core engagement.

Easier and harder variations

Easier

Standard crunches (no leg lift). Or reverse crunches (no upper body lift). Or perform the knee touch with smaller range.

Harder

V-ups (legs straight throughout). Hold a weight in the hands. Or progress to jackknife sit-ups.

Alternative exercises

Jackknife sit-up
More demanding combined ab exercise with similar pattern but greater range.
V-up
Hardest version with straight legs. Creates a longer lever arm.
Tuck crunch
Similar combined exercise with knees held in tucked position throughout.

How to program the Knee Touch Crunch into your training

Knee touch crunches work as accessory or stand-alone core exercise. Sets and reps: 3 sets of 12-20 reps with 30-60 seconds rest. In a complete core circuit: 3 sets of 15 knee touch crunches, 3 sets of 30-second front planks, 3 sets of 12 reverse crunches. Done 2-3 times per week. Daily moderate volume is fine.

Recovery and frequency

Knee touch crunches at moderate volume have low recovery cost — daily training is fine.

Frequently asked questions

How many sets and reps should I do?

3 sets of 12-20 reps with 30-60 seconds rest.

How often should I train this exercise?

2-3 times per week as part of a structured program; daily at moderate volume is fine.

Knee touch crunch vs standard crunch: which is better?

Different tools. Standard crunches train upper abs only. Knee touch crunches add lower-ab work. Use knee touch for combined work; use standard for focused upper-ab volume.

Will knee touch crunches give me visible abs?

They build the muscle, but visible abs come from low body fat.

Why do my hip flexors get tight from this exercise?

The leg lift component activates the hip flexors significantly. Daily hip flexor stretches between sessions help.

Are knee touch crunches good for beginners?

Yes — they're an accessible combined ab exercise that's appropriate for most fitness levels. Build to standard versions before progressing to V-ups or jackknife sit-ups.