Yes, arm pump is a phenomenon experienced by many athletes, especially in sports like mountain biking and rock climbing (2). When you do things like holding onto handlebars or climbing, your forearm muscles can fill up with too much blood because of this. The extra blood can squish the nerves and blood vessels in your muscles. Your arms may feel hurt and weak, and it is hard to hold onto things.
Even though an arm pump isn’t a significant medical problem, it can make you uncomfortable and cause you to not do as well in your activities.