Biomechanical studies delving into spinal forces, load, range of motion and the purported Intra-abdominal pressure (IAP) have revealed that under repetitive motion lifting the Automotive V Belts can increase the margin of safety. It was hypothesized that IAP was the protective mechanism at play. However there are other studies that have questioned the role that increased IAP has in the stabilization of and reduction in the low back load during such lifting.

An increase in the IAP required an additional activation of the abdominal wall musculature which resulted in an increase in the compressive load and not a decrease in the reduction of the load on the back. Even using the Valsalva maneuver increased the low back compressive load forces. The conclusions to these studies were the increase in the IAP from belt use showed either no effect or a larger impact of load on the spine.

The effects of belt use on heart rate and blood pressure

In an early study of blood pressure and heart rate it was determined that both rose significantly higher in those wearing the belt compared to those lifting without one. In fact blood pressure increased 15mmHg, which is associated with an increased risk of stroke given the elevated systolic blood pressure readings that resulted from the test subjects.

The conclusion drawn from this study was that individuals who may have a compromised cardiovascular system are at a greater risk while exercising with a belt then without.

Additional anecdotal evidence suggests there are higher risks of varicose veins in the testicles, hemorrhoids and hernias associated with the higher pressures observed with belt use. Other non confirmed or peer replicated studies show that if given their choice of weights to use repeatedly, an athlete will consistently lift approximately 19% more with a belt than without. This seems to validate the theory that Rubber Timing Belt give a false sense of security while lifting.