Performed fervently by avid gym-goers for decades past, the sit-up has become one of the most widely known exercises to the layperson. Sharing the same exposure as push-ups and squats, the sit-up is usually the first exercise to come to mind when most consider an abdominal exercise. The only trouble is that few realise the significant contribution of the hip flexor muscles whilst executing a sit-up or one of its many variations (see ‘Sit-ups, back pain & the side effects of living in the 21st century’ article for more on this). In contrast, the Janda sit-up is one variation that goes against the grain. When executed properly, a Janda sit-up is one of the best ab exercises that one can perform.
Invented by Czech Professor Vladimir Janda, the Janda Sit-up aims to relax the hip flexors, recruit the glutes & hamstrings, enhance abdominal activation, and reduce stress on the lower back. This sit-up variation works by the principle of reciprocal inhibition, which states that when an agonist muscle group is contracting, the opposing muscle groups (antagonists) will relax. This is a natural mechanism incorporated by the body, and is used in order to save energy and make movements more efficient. A simple example of this is flexing the elbow during a bicep curl. The bicep (agonist) fully contracts to bring the forearm towards the upper arm. The opposing antagonistic muscle group (the triceps), which are responsible for straightening the arm, consequently relax so as not to impede the work of the biceps. Professor Janda used this mechanism to limit the involvement of the hip flexors when performing his variation of the sit-up. He found that if the subjects in his experiments performed the sit-up exercise whilst contracting their glutes and hamstrings hard, the hip flexors (the antagonists) would relax more, and hence, increase the involvement of the abdominals. So how do you perform a sit-up where you are engaging the glutes & hamstrings, whilst relaxing the hip flexors, and consequently working the abs more? Try the following:
Performing the Janda Sit-up:
Assume the conventional 90 degree bent-knee sit-up position on the floor. Have a training partner hold your legs just below the calves or wrap a resistance band around the lower legs and anchor it to something sturdy in front of you. (Even better – wrap the band around something up at 45 degrees if possible) Your feet should remain in contact with the floor at all times during the movement. Fold your hands across your chest, inhale, squeeze your butt hard, and slowly sit up whilst applying steady pressure against your partner’s hands (or the resistance band) with your legs. Sit-up to approximately 30 degrees whilst gradually exhaling as you approach the top of the movement. Inhale again and lower yourself all the way to the floor, pushing against your partner’s hands the whole time. Relax for a second, then repeat.
Remember, the abs are most active during the first 30 degrees of a sit-up (see ‘Sit-ups, lower back pain and side effects of being a 21st century human’ article for more on this). Hence, you should stop at this point as the tension in the abs will start to diminish with further movement past this position.
Upon doing this exercise for the first time you will notice it is much harder than a conventional sit-up. The speed of movement and higher reps are a lot harder to come by, and you may only get 2-3 reps per set the first time through. Build up to 10-12 reps for a few sets and consider the progression options below to improve further:
Level 1: Arms straight beside thighs
Level 2: Arms across chest
Level 3: Hands behind head
Level 4: Arms straight over head
Level 5: Hold weight across chest
It is worth noting here that the hip flexors will “relax more” instead of “relax entirely” when executing the Janda sit-up. Studies have shown that while the Janda Sit-up does reduce hip flexor muscular activation significantly compared to other sit-up variations, it cannot completely relax the hip flexors due to the nature of this muscle group and the body’s position during the movement[ii]. It is important to consider your anatomical situation before attempting the Janda sit-up for the first time. The sedentary nature of today’s workforce and lifestyle can have a large impact on one’s pelvic position and lower back integrity. People who sit for long periods of time often have a forward tilt in their pelvis, weak glutes and a swayed back. These conditions impede the effectiveness of most exercise movements including the Janda Sit-up. If you cannot feel your abdominals working hard during the movement or worse yet, you feel the hip flexors contracting hard and your lower back hurting, you may need to look at the aforementioned article again (click here for the article) and apply its remedies. Aim to complete at least 3 sets of 20 McGill Crunches before progressing to a more advanced exercise such as the Janda Sit-up.
[i] Electromyographic muscle activity in curl-up exercises with different positions of upper and lower extremities.
[ii] Influence of pelvis position on the activation of abdominal and hip flexor muscles.