also a tool that helps strengthen the abs. It may be more effective than the crunches on the floor because the abs do more work as the legs are not involved in the exercise. With respect to the Ab-Slide, the study performed by Bird et al. showed greater muscle activation in the upper rectus abdominis, lower rectus abdominis, and external oblique when compared to the standard abdominal crunch. The Ab-Slide has proven to be an effective tool in strengthening the abdominal muscles from a concentric muscle action perspective. However, this research does not support replacing the traditional crunch exercise with the Ab-Slide gadget due to the lack of proven effectiveness in the eccentric loading of the abdominal muscles and the greater postural control. Potentially the most effective equipment for abdominal strengthening is those that offer the least stability. Examples include the CoreFitnessRoller, bodyweight suspension training such as TRX, and stability balls with or without the Halo. Safety of abdominal exercises Abdominal exercises also put some degree of compressive force on the lumbar spine, putting unwanted stress on the lower back. In addition, exaggerated abdominal exercise can cause respiratory problems. A study of twelve exercises concluded that no single exercise covered all abdominal muscles with high intensity and low compression. The benefit of focused training on the "deep core" muscles such as the transversus abdominis has been disputed, with some experts advocating a more comprehensive training regimen. See also Abdomenizer Abdominal fat Chin-up bar Core (anatomy) Crunches Pilates Roman chair Situps Spot reduction References Bodyweight exercises Abdomen