Sounds right, but note that these guys are studying strength and endurance, the usual fodder for athletic sports. Golf doesn't have much to do with strength and endurance as there is too much time between shots.
The brain is protecting energy reserves against exhaustion, which can prove fatal if a predator shows up just when the exhausted person / animal flops on the ground to recover.
It is unusual for an animal to drive itself to it's limit on purpose, just to win a chunk of metal or some paper with Presidents' pictures on the paper. Obviously, the flight-fight reaction can power an animal to far exceed it's own limits, to the extent that a female can lift and move a car, and incur physical trauma in the process. So there are "survival" occasions when the safety / protective safe guards get ignored.
But in general, I have no reason to doubt there would be a limiting by the brain.
On the other hand, I don't quite believe that "deception" to the athlete's "conscious mind" is all required to disable or evade the limit. There must be something more to this than that. ordinarily, brain safety / survival protections ignore the conscious, and wouldn't care a fig about what the conscious mind regards as the limit.
Teasing out the variables, it is likely that the "two competitors" on the screen used in the deception, one being the athlete personally, probably injects a factor the researchers are not noticing correctly, like self-regard plus competition plus mimicking the on-screen action. These factors are just the sort to affect the brain, and the reserachers don't seem to be avoiding this taint.
I'll check more into this and report back.
Putting Coach and Theorist