Jackknife Sit-Up

Review: Jackknife Sit-Up

Nov 18, 2012 4:51 PM: The pulse ups really get your abs burning The pulse ups really get your abs burning-See Less

Review: Jackknife Sit-Up

Oct 7, 2012 11:27 PM: Do these with a medicine ball, amazing workout Do these with a medicine ball, amazing workout-See Less

Review: Jackknife Sit-Up

Jun 1, 2012 6:54 PM: Seriously, are people trying to destroy their low backs? Seriously, are people trying to destroy their low backs?-See Less

Review: Jackknife Sit-Up

Dec 14, 2011 8:40 PM: one of the most brutal ab exercises ever one of the most brutal ab exercises ever-See Less

Review: Jackknife Sit-Up

Dec 5, 2011 8:17 AM: This one burns like hell but I still love it This one burns like hell but I still love it-See Less

Review: Jackknife Sit-Up

Oct 28, 2011 5:35 PM: love it love it-See Less

Review: Jackknife Sit-Up

Aug 26, 2011 7:30 PM: great workout really tough on the abs. btw does work upper abs as well or its more towards just lower? great workout really tough on the abs. btw does work upper abs as well or its more towards just lower?-See Less

Review: Jackknife Sit-Up

Mar 24, 2011 7:56 AM: i love to hate this. So freaking hard...so much so that i cant freaking do it. :( i love to hate this. So freaking hard...so much so that i cant freaking do it. :(-See Less

Tip: Jackknife Sit-Up

Jan 22, 2011 9:48 AM: VEry good VEry good-See Less

Tip: Jackknife Sit-Up

Mar 4, 2010 3:33 AM: during the exercise try to reach your leg with you hand and straighten your knees
during the exercise try to reach your leg with you hand and straighten your knees
-See Less

Jackknife Sit-Up

Nov 18, 2012 4:51 PM: The pulse ups really get your abs burning The pulse ups really get your abs burning-See Less

Jackknife Sit-Up

Oct 7, 2012 11:27 PM: Do these with a medicine ball, amazing workout Do these with a medicine ball, amazing workout-See Less

Jackknife Sit-Up

Jun 1, 2012 6:54 PM: Seriously, are people trying to destroy their low backs? Seriously, are people trying to destroy their low backs?-See Less

Jackknife Sit-Up

Dec 14, 2011 8:40 PM: one of the most brutal ab exercises ever one of the most brutal ab exercises ever-See Less

Jackknife Sit-Up

Dec 5, 2011 8:17 AM: This one burns like hell but I still love it This one burns like hell but I still love it-See Less

Jackknife Sit-Up

Oct 28, 2011 5:35 PM: love it love it-See Less

Jackknife Sit-Up

Aug 26, 2011 7:30 PM: great workout really tough on the abs. btw does work upper abs as well or its more towards just lower? great workout really tough on the abs. btw does work upper abs as well or its more towards just lower?-See Less

Jackknife Sit-Up

Mar 24, 2011 7:56 AM: i love to hate this. So freaking hard...so much so that i cant freaking do it. :( i love to hate this. So freaking hard...so much so that i cant freaking do it. :(-See Less

Jackknife Sit-Up

Mar 1, 2010 2:38 PM: perfect and feeling great progress perfect and feeling great progress-See Less

Jackknife Sit-Up

Jan 22, 2011 9:48 AM: VEry good VEry good-See Less

Jackknife Sit-Up

Mar 4, 2010 3:33 AM: during the exercise try to reach your leg with you hand and straighten your knees
during the exercise try to reach your leg with you hand and straighten your knees
-See Less

Jackknife Sit-Up

Mar 3, 2010 8:33 PM: Sit on a bench, rather than on the floor, with your body perpendicular to the bench. This will allow for a greater range of motion (downwards) and will also force you to balance thus engaging your core. Sit on a bench, rather than on the floor, with your body perpendicular to the bench. This will allow for a greater range of motion (downwards) and will also force you to balance thus engaging your core.-See Less