Hmm, I'm 53 and wear my belt frequently as a safeguard to lower back injury. I agree with the strong core requirement so I do core work as required. I think you younger guys shouldn't wear belts until you are in the 80% or above max area. But, as an older lifter i believe the belt prevents back injury by stabilizing the core. IMHO
During the exercise yes but overall no.
The idea that a belt will protect you is unproven and if anything the evidence goes against it. (Not knockin ya, just stating facts)
About to drop some science on y'all
In some studies done (Reddell and colleagues, 1992, Mitchell and colleagues, 1994, Wassell and colleagues, 2000) they found evidence that use of belts for workers already injured might slightly benefit from belts to prevent re-injury, but the evidence is weak. Although there is still some evidence there, further research indicated that there is no support that weight belts will prevent injury to those un-injured workers. Actually, the risk of injury seemed to increase in those not injured prior to belt usage!
Basically the belt is used as a crutch and like the study says, crutches are fine for those with Injuries but it can set so much out of alignment, including diaphragm breathing which is easily one of the biggest power producers on heavy lifts.
A study by McGill and colleagues (1990) showed that weight lifting belt usage showed no difference in lower back/abdominal muscle activity than those not utilizing belts. Reyna and colleagues (1995) and Ciriello and Snook (1995) both showed that belts provided no reduction in fatigue or loading of the lower back extensors with belt use. Therefore one can conclude that the lower back musculature is firing the same regardless of belt usage.
Along with that contraction of the belt is the problem of blood flow and since this thread is based off of dudes wearing it all day..
One study by Hunter and colleagues (1989) looked at how blood pressure and heart rate were affected by belts. They took 6 individuals and had them perform dead lifts, riding bicycles, or perform a one-armed bench press while wearing and not wearing a 4 in. weight belt. The lifting exercise resulted in an increase in blood pressure (up to 15 mmHg) and significantly higher HR as well.
So there ya go, worse for breathing, the muscles, the core, and even your heart. Science!