If you suffer from arm-pump, this is probably why

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I think it’s pretty safe to say we’ve all suffered from arm-pump while racing motocross - some of us get every now and then, while others face it every weekend they go racing. 

I recently had motorsport strength and conditioning coach Andrew Hammer (yes, he is my brother) from Driven Athlete Training on The Motocross Podcast, and amongst our conversation on motocross fitness, he detailed why riders suffer from arm-pump. 

Now from what Andrew had to say, there are generally two types of riders who get arm-pump - those that get it at the start of the race before it disappears, and those that suffer it a number of laps into a race.

motocross arm pump


According to Andrew, encountering arm-pump at the beginning of a race comes down to a lack of warming up. 

He explains that just like you would warm-up for any other sport or training session, you need to do the same prior to riding or racing motocross.

“Some riders will also get arm-pump at the start of a ride, and it will actually get better and disappear - only in that case, it’s a warming up problem,” says Andrew. 

“It’s just like any other muscle - people think arm-pump is this mythical thing that has no answers - there are people taking special supplements, using special devices, and there are people rolling a piece of string around a brick. 

motocross arm pump

“It all targets the symptom - it’s not the problem, the problem is the rest of your body is weak. So if you get arm-pump at the start of a ride, it’s a warming up problem.

“If I go to the gym, put 100kg on the bar for a deadlift and don’t warm up, my legs feel like shit, they start to burn and I start to get a sore back and I start cramping up - all the same symptoms [in your arms] when you get arm-pump at the start of a ride. 

“People think that riding motocross is different to any other sport or being at the gym - obviously there are components that are different, but in terms of how you feel, it’s not that different. 

“If you’re getting arm-pump at the start of a ride, it probably means that you’ve done no warming up and then gone out on the track with this 100kg bike and tried to hold it flat out.”


If you experience arm-pump as the race progresses, then Andrew says it’s likely due to fatigue and ultimately a lack of preparation. 

“The cause of arm-pump is very rarely the arms, and that’s the first challenge that people have,” he explains. “They think that because something is sore, it’s the problem - that’s very rarely the case. 

“The reason riders get arm-pump is that the rest of their body is no longer holding in position on the bike - they no longer have the strength to grip with their legs to hold the right posture and control the bike. 

“So when they turn the throttle, the bike always wants to take off from them. At the start of the race when they’re not fatigued and they’re fresh, they’re in control of the bike, they’re in the right position, they’ve got their elbows up, they’re gripping with their legs and everything is nice and strong. 

motocross arm pump

“As soon as they start to fatigue, they get weak - when you’re weak, you don’t hold those positions anymore. So when you turn that throttle on and the bike goes forward, you don’t move forward with the bike - the bike wants to take off from you. 

“When the bike wants to take off from you and the only thing you have holding onto the bike is your arms, your arms are going to get ripped off. 

“If you like at the size of your forearms - look at my forearms, they’re not that big in comparison to the size of my legs - if you look at the size of my quads, my hamstrings, and my glutes - they are massive powerhouse muscles - they are huge, they mean business and they can move some weight.

“Instead of having your hamstrings, your quads, your glutes - all these big powerhouse muscle groups holding you in position at the start of a ride, what happens is they don’t work properly anymore because you’re week, fatigued, or haven’t trained properly or you didn’t eat to perform.

“So you get fatigued, and you hang on with your hands. So now you have these small muscle groups in your forearms trying to deal with this 100kg."