You can't pull the brake lever, you can barely move your fingers enough to hold on to the bike because the trapped blood in your forearms makes gripping nearly impossible—you have compartment syndrome, known as 'arm pump', the destroyer of motorcycle racers. Anyone who's ever tried seriously to improve as a motocross rider has experienced arm pump. And although you might need to move up the ranks in short-circuit racing before it afflicts you, it's still almost inevitable, unless your name is Valentino Rossi.
MotoGP recently released a video on YouTube of last September's Hall of Fame dinner, which included Rossi, Dani Pedrosa, Casey Stoner, Giacomo Agostini, Jorge Lorenzo, Freddie Spencer, and Kevin Schwantz. At one point during the dinner, the discussion turned to arm pump, which is when we found out that Rossi won the MotoGP genetic lottery and never suffered from it during his career. The conversation was even more contrasting because Pedrosa was involved and suffered massively from arm pump throughout his career.
Rossi told the group, "I've had it a bit with motocross sometimes, but in MotoGP, never... In my opinion, it’s genetic luck,” continued Rossi before saying, "It depends on your genes; how big your forearms are... That was a great luck [for me].” Now, contrast this to Pedrosa, who had the most extreme surgery you can get to solve the problem—removal of the forearm muscle fascia—and save his career in 2015.
During the dinner, Rossi asked Pedrosa if the surgery helped, to which he replied, "A bit… In my case, if I did a lot of [weight] training in the gym, it got much worse... But I needed to train in the gym because [of my size].” Even after the surgery, Pedrosa would retire from being a full-time rider in 2018 with 31 race wins to his name, making him the most successful rider to have never won a MotoGP premier-class championship.
Interestingly, Rossi is one of the tallest riders to have competed in MotoGP, at 1.81 cm, and Pedrosa is one of the shortest, at 158 cm. Pedrosa was famously told that he was too short for MotoGP, and some people thought his stature meant he suffered more when he crashed than other riders. With this in mind, add the fact that Pedrosa said he was essentially riding with one arm during the 2014 season, and it's fair to say he wasn't on the winning side of the MotoGP genetic lottery, but he achieved an insane amount regardless.
