Weightlifting belts are reportedly used by a quarter of recreational weight trainers, and their benefits to lifting performance is supported by a large body of research. The data suggest that belts reduce compressional forces on the spine, with most research implicating increases in intra-abdominal pressure (IAP). One study has suggested, alternatively, that the reduction is due to a moment generated by the belt itself.
Research reports consistently higher lifting velocities with weightlifting belts, and there is even some evidence¹ ², which contradicts the common assumption that they are detrimental to core development, that they may improve lumbar (erector spinae) and abdominal (rectus abdominis) muscle activation. Although this claim may seem dubious—how might an accessory that supports the core muscles bolster their development?—it is not out of the bounds of possibility.
However, all of the research hitherto seems to have been focused on the immediate physiological and biomechanical differences between the belt and no-belt states, and their consequent effect on performance. That is, a weightlifting belt may indeed increase erector spinae activation whilst the belt is worn, but that does not imply, necessarily, that the same activation will occur after the belt is removed. There appears yet to be no evidence that weightlifting belts offer any general benefit to training and adaptation.
From a personal perspective, at my peak, I performed my heaviest squat and deadlift, which represented 230% and 270% of my body-weight, respectively, without wearing a belt. And not once did I ever wear a belt in training. But that was as much personal preference as it was rationale. Clearly we are able to lift heavily and safely without a belt, but that does not imply that it is ideal.
So my question is this: does anyone know of any objective evidence that weightlifting belts either improve or hurt long-term development of core/trunk strength? I am especially interested in their effect on the development of the core muscles (particularly the diaphragm, pelvic floor, multifidus, and transversus abdominis).