If you're like me, you probably go to the gym in hopes of attaining a six-pack, powering through numerous crunches in every angle possible. A study in 2006, however, showed that these abdominal exercises don't actually reduce the fat around your stomach that you desperately want gone.
The study recruited 24 healthy but sedentary participants "(14 men and 10 women), between 18 and 40 years." They were assigned to two groups: an experimental, abdominal exercising group and a control, non-abdominal exercising group. Within the duration of 6 weeks, the experimental group performed "7 abdominal exercises, for 2 sets of 10 repetitions, on 5 weeks (-1)" and the control group received no intervention.
All participants "maintained an isocaloric diet," which means that they ate whatever they wanted to as long as they had the same amount of carbs, proteins, and fats every day. The results surprisingly showed that there was no significant difference between the two groups when considering body weight, body fat percentage, abdominal circumference, or abdominal subcutaneous fat (abdominal fat beneath the skin). In other words, as the authors put it, "Six weeks of abdominal exercise training alone was not sufficient to reduce abdominal subcutaneous fat and other measures of body composition." However, they did find that the experimental group "significantly improved muscular endurance to a greater extent" compared to the control group.
What's more, some researchers advocate for the abandonment of sit-ups altogether due to the negative effect on the spine it can have. This is because of the large compression forces on your spinal discs. In a 2001 study, it was found that "intervertebral disc herniation may be more linked to repeated flexion-extension motions" that are similar to the motions during sit-ups. Stuart McGill, a spine biomechanics professor at University of Waterloo mentions in his book, Lower Back Disorders that "The US National Institute of Occupational Safety and Health has set the action limit for low back compression at 3300 N; repetitive loading above this level is linked with higher injury rates in workers" – however, he found that "3,230 N with straight legs, 3,410 N with bent knees" was imposed on the spine with each sit-up when he studied "12 young men performing the exercises."
Perhaps the solution is to not participate in sit-ups at all but to do planks instead. Dr. Mike Bracko, a sports physiologist, mentions that "planks use neutral spine loading and not trunk flexion – as in sit-ups – to strengthen the abs." Furthermore, according to LIVESTRONG, "unlike a sit-up, a plank engages multiple muscle groups, including your rhomboids and trapezius in your upper back, your transverse abdominis, your rectus abdominis — the six-pack of muscles in your abs — your obliques and even the abductors in your upper thigh." I'd much prefer this over not getting abs and hurting my lower back!
