The sit up is among one of the most common exercises for improving the appearance and function of the various core muscle groups, with its incorporation being in practically every training routine that does not otherwise utilize similar core training exercises.
However, due to its risk of injury or other purposes, the sit up may need to be substituted out with another exercise of similar muscle group activation pattern - often one that also shares many of its relevant biomechanics and form cues.
The process of substituting out the sit up with a similar alternative exercise is not as complex as it may seem, with such exercises like the crunch, dragon flag or even good morning all presenting similar training stimulus and muscle group activation with few of the sit up’s drawbacks.
The sit up presents several issues related to its mechanics and training intensity that can all be remedied by alternating it out with a subsequent exercise of similar training results.
Generally, the largest issue with the sit up is in the way it may place force on the lower spinal cord, with its method of utilizing spinal flexion in a repetitive and unsafe manner resulting in lower back injuries that may be difficult to rehabilitate.
This is in direct connection with the fact that the sit up makes a poor rehabilitatory exercise for individuals with postural issues, or those with a weakened group of core and lower back stabilizers - all of which will only be worsened to an extent by the performance of sit ups in excessive volume.
Apart from these factors, the sit up is also not the best for specific muscle group activation in regards to the core stabilizer muscles such as the rectus abdominis, transverse abdominis and obliques, especially in comparison to the majority of alternative core training exercises.
A suitable sit up alternative must share several of its key characteristics while having less of its more significant drawbacks, with such things like core muscle group activation and a low to intermediate level of resistance being important factors in deciding on an alternative exercise.
Generally, isolation exercises solely training the abdominal muscles, or compound exercises that place great emphasis on the core stabilizer muscles can fill the role of a sit up replacement exercise - so long as their particular characteristics fit the exerciser’s training goals and conditions.
The sit up will usually take the place of a secondary isolation exercise meant to target the core in a manner that other exercises present in the workout session would not, especially in regards to dynamic muscle group contraction.
As such, any alternative to the sit up must also be capable of taking such a place, save for instances wherein the alternative exercise is of a compound nature, or of a training intensity significantly higher than the sit up itself.
In the event that the sit up exercise is being substituted with an alternative movement of a lower intensity than the sit up, all that is required is to simply increase the total volume of repetitions per set for the alternative exercise.
For periodization training programs, the sit up alternative must fulfill the characteristic of whatever training phase the sit up was originally a part of, with endurance or hypertrophy focused periodization phases requiring an exercise that induces the corresponding stimulus and intensity.
In the event that the sit up is being substituted simply for reasons that do not preclude the usage of its variations (such as in the case of ineffective training stimulus), the usage of minor modifications to the form of the sit up itself should be more than sufficient to remedy the situation.
This will usually take the form of placing additional stress on the core stabilizer muscles so as to increase muscle group contraction, or reduce the stress the exercise will place on the spinal column by reducing the load on the lower back.
A variation of the sit up that requires the exerciser to angle their body in such a way that the spine is forced into a neutral position and the range of motion involved therein is greatly increased - the decline sit up makes use of a decline bench or similar implement in order to achieve such a feat.
Hooking the exerciser’s feet into the stirrups of the decline bench, all that the exerciser is required to do is to simply perform a full repetition of the sit up, though with the added caveat of beginning the repetition entirely from the base of the bench itself.
This will force the core stabilizers to contract in both a static and dynamic manner - as well as reduce the risk of spinal injury as it is placed in a neutral position with less shear force impacting the lumbar and thoracic portion of the spinal column.
In addition to this, the increased range of motion will result in significantly more intense muscle contraction alongside a lengthened time under tension, thereby also resulting in superior training results.
A standard sit up with the exerciser rising until they come into contact with their knees instead of some distance away, the full sit up is a suitable alternative variant to the standard sit up for exercisers desiring a more intense muscle contraction of the core muscles without the use of additional equipment.
However, due to the fact that the full sit up is simply a sit up with an increased range of motion, much of the same issues that plague the traditional sit up such as risk of spinal injury are still entirely present - making it unsuitable for individuals wishing to avoid these issues.
Another variation of the sit up with a minor change in form that can significantly alter its angle of resistance, risk of injury and level of training stimulus - primarily by the exerciser raising their limbs and suspending them in the air throughout the repetition.
This will greatly increase the level of static contraction and stabilization that is demanded of the core muscle groups, resulting in better training stimulus that does not place as much risk on the spinal column as the shear force placed on the lumbar portion of the spine is reduced.
Save for certain circumstances that prevent the performance of such an exercise, the crunch is one of the best possible alternatives to the sit up in a way that it may even be considered a direct upgrade in certain terms.
This is due to the fact that the crunch is simply a modification of the standard sit up that reduces the relative risk of injury by shrinking the range of motion during the exercise.
This comes at a cost, however, as a reduction in the range of motion will remove the usage of certain smaller muscle groups normally trained to an extent by the sit up, such as the hip adductors and lower back - both of which are activated in a small capacity by the sit up.
The crunch is quite similar to the standard sit up, but with the sole muscle group activation of the abdominal muscles - with no other muscle group being involved in any significant capacity.
This will generally result in less shear force being placed on the lower back and spinal column, as well as allow for individuals of reduced flexibility to perform the exercise more comfortably as the crunch is essentially considered a “half sit up” because of its greatly reduced range of motion in comparison.
Primarily, the main benefit of the crunch as an alternative exercise to the sit up is in the fact that it imposes little to no risk of injury so long as proper form is utilized - alongside the fact that its reduced range of motion will allow for a greater amount of repetition volume be performed, allowing for more significant abdominal muscle training without fatiguing other muscle groups.
As the crunch solely activates the abdominal muscles with no other muscle groups acting as auxiliary mover muscles, it will quickly fatigue the exerciser’s core and any strength it may output - thereby requiring that the crunch be performed around the end of the workout session so as to avoid the core giving out during the performance of another exercise, something that may result in injury.
Apart from this, the crunch will also expend far less energy than the sit up, making it a less suitable exercise for individuals seeking to burn calories in order to reduce their composite bodyfat percentage.
In cases where the crunch or any subsequent variations of the sit up are not suitable to act as alternatives to the traditional sit up itself, supplanting it with another core isolation exercise may be the only possible choice for the exerciser.
Luckily, the list of possible core isolation alternatives to the sit up is quite long, with such exercises like the plank fulfilling the role of isometric time under tension alternatives, and other exercises such as scissor kicks being a possible choice for individuals with a history of back pain from the sit up.
The Russian twist is a core isolation exercise that activates not only the abdominal muscle group but also places a great level of emphasis on the obliques along the side of the lower torso - allowing for a training stimulus that is quite effective at building up core strength and endurance.
This makes the russian twist an excellent alternative for athletes and exercisers seeking a more intense and wide reaching training stimulus than the sit up - though the compressive and shear forces it places on the lower back make it rather unsuitable as an alternative for individuals with issues in that particular area.
This factor, alongside its somewhat more complicated form and higher level of difficulty make it an alternative best reserved for more experienced exercisers with no history of issues associated with core exercises.
Among one of the most popular static core exercises, the plank is an alternative to the sit up best used for individuals with poor flexibility, or those seeking a different form of training stimulus that does not directly require dynamic muscular contraction be utilized.
The plank is also quite suitable for individuals with a history of soft tissue injuries of the lower back, as it places little to no strain on the muscular and connective tissue structures therein - though it is still important that they utilize proper form in the exercise, despite its relatively lower risk of injury.
Translating the sit up to the planks in terms of exercise programming may be rather difficult however, as the sit up is generally measured in repetitions while the plank is measured in time under tension.
As such, when substituting the sit up with the plank, it is better for the exerciser to simply go by perceived rate of exertion until they have a better grasp on their own physical capabilities in regards to this particular exercise.
Also known as flutter kicks, scissor kicks differ from the sit up by targeting the lower portion of the core stabilizers in a more significant manner - while also recruiting several muscle groups in the lower back, hips and legs that are not normally contracted in such a manner during a repetition of the sit up.
This allows for the scissor kick to act as an alternative in the capacity of a calorie burning counterpart to the sit up, or for individuals seeking to induce more muscular contraction on the lower portion of the abdominal muscles.
In terms of injury reduction, the scissor kick places far less shear force on the spinal column than the sit up - though it may still aggravate or even induce lower back muscle pain due to the exerciser forcing them to contract as they raise and hold their legs in the air during the exercise.
1. John D. Childs, Deydre S. Teyhen, Patrick R. Casey, Kimberly A. McCoy-Singh, Angela W. Feldtmann, Alison C. Wright, Jessica L. Dugan, Samuel S. Wu, Steven Z. George, Effects of Traditional Sit-up Training Versus Core Stabilization Exercises on Short-Term Musculoskeletal Injuries in US Army Soldiers: A Cluster Randomized Trial, Physical Therapy, Volume 90, Issue 10, 1 October 2010, Pages 1404–1412, https://doi.org/10.2522/ptj.20090389
2. Carolyn Richardson, Rowena Toppenberg, Gwendolen Jull, An initial evaluation of eight abdominal exercises for their ability to provide stabilisation for the lumbar spine, Australian Journal of Physiotherapy, Volume 36, Issue 1, 1990, Pages 6-11, ISSN 0004-9514, https://doi.org/10.1016/S0004-9514(14)60514-6. (https://www.sciencedirect.com/science/article/pii/S0004951414605146)
3. Comfort P, Pearson SJ, Mather D. An electromyographical comparison of trunk muscle activity during isometric trunk and dynamic strengthening exercises. J Strength Cond Res. 2011;25(1):149–54. pmid:21157393.