Very challenging for the shoulders when holding it up!

Great question. So Ill start with why Mat Fraser I think Mat Fraser used this and why I think its a great tool for endurance in the arms. When it comes to training the arms, most of what we do to train the arms are exercises that take 10 seconds to MAYBE 2 mins for a very high rep arm exercise. This means that most of our arm training is for STRENGTH, POWER, or MUSCLE ENDURANCE (local muscle endurance). I cant really think of a scenario where we train our arms for longer than 2 minutes without resting somewhere in there. Even if someone does burpees for 30 minutes, the arms arent working constantly and do get rest. So if we train legs for long durations, long runs, biking, etc. utilizing long endurance sessions over 30 mins, why wouldnt we do that with the arms. It could potentially improve mitochondria count in the arms, and improve overall endurance, and volume tolerance of the arms. Now, one would have to already be VERY strong, otherwise this will cut into strength training a bit, and strength gains. This is an area Mat was probably willing to lose a little bit in since he was already very strong. So its more building up the ability to work the arms for 30 mins straight or so, at a lower intensity in my opinion, which would have some carry over to long endurance events with arm movements, high volume training tolerance in general, AND also being able to tolerate the high volume of damage on the arms at the Crossfit Games. As for the rehab aspect, I imagine there is a small effect there but I am unsure. Mat did however mention that he used this apparatus for active recovery too which makes sense. You are spot on, it would increase bloodflow which would be greatly beneficial to speeding up recovery. As for noticing any kind of strength, i havent noticed that but I dont think it will help with srength in general anyhow. Great questions and thanks for commenting!!