The Jack Knives ExerciseAll Exercises -> Abdominal Exercises -> Jack Knives
Primary Muscle(s) and Equipment
|Abdominal, Lower Abdominal, Belly, Stomach, Hip Flexors, Calisthenics, Core Strength, Isolation, Bench, Upper Body, Washboard|
How to do the Jack Knives
This exercise can be performed with your knees bent or kept straight. Lie on the ground (beginner) or a bench (advanced) with your lower body not on the bench. Complete a crunch and bring your knees and shoulders together. This exercise takes a lot of balance and is great for any athletes.Spotter Information:
Note: If you feel you are starting to lose your balance, put your foot down. A bench allows for more stabilizer muscles to be activated to maintain your balance.
Averages for MyFit Users
The table below represents data from over 200,000 exercise logs
and gives us an average for this exercise.
|Average Weight Lifted||Average Reps
||One Rep Max Average|
How do I figure out a good starting weight?
Based on an average weight lifted of 10.6 lbs for all MyFit users we suggest you start at 50% of that weight:
5 lbs and aim for 12-15 reps.
Abdominal Barbell Rollouts
Abdominal Dragon Flags
Ball Knee Crunches
Ball Side Crunches or Bends
Cable Side Bends
Dumbbell Side Bends
Exercise Ball Abdominal Leg Raises
Exercise Ball Abdominal Russian Twists
Exercise Ball Medicine Ball Throw
Exercise Ball Oblique Twists
Exercise Band Ab Ball Crunches
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