Forearms feel like they're blowing up on long descents? We explain what's causing it, and what you can do to eliminate it


Whether it is clips vs flats or analog vs e-bike, there seems to be a lot of division in mountain biking. And while most of it is clearly manufactured, one thing we can all agree on is that no one wants arm-pump.

This painful condition builds up in the forearms, wrists and hands on long descents, and with it a burning sensation and growing weakness that makes it hard to hold on and control the bike. 

What is arm-pump and what causes it?

If the doctors who perform carpal tunnel release surgery are to be believed, it’s caused by constricted blood flow in your forearm which leads to a build up of metabolites in the surrounding muscles with an associated loss in grip strength.

And while we’re not promoting surgery to deal with arm-pump here, the mechanism appears to be sound as it is not that dissimilar to getting a crazy muscle pump from a high-rep set of exercises performed in the gym. That said, carpal tunnel release surgery doesn’t always eliminate arm-pump. 

Holding on tight, over a sustained period of time, leads to a reduction in blood flow and oxygen to the arm muscles, causing ischemic pain. Pic: Andy Lloyd.

Less invasive approaches to tackle arm-pump include; wrist stretches, hydration strategies, supplementation and massage, all with very little evidence to back up their efficacy for reducing arm-pump.

So what do most riders do when they get arm-pump? We simply pull over to the side of the trail and shake it out before continuing our ride. 

Less fatigue means less arm-pump, pain and simple

Now if you’re racing, that’s not a good strategy for dealing with arm-pump, even if it is better than crashing in the next corner because you simply can’t hold on, or don’t have the strength to pull the brakes hard enough. And even if you’re not up against the clock, who wants to stop halfway down an amazing trail and interrupt the flow of the ride and the dynamics of the group, just to shake their arms out?

So what to do instead. Now you may have heard some trainers and pro riders say you should not do any grip or forearm strength training, as having more muscle on your arms actually makes arm-pump worse.

Well, that’s just complete nonsense and here’s why. 

Bosch e-bike ABS brakes

Strong forearms and grip mean you won’t need to exert as much of your strength to hold onto the bars or squeeze the brakes

If you have a very high level of grip strength, the effort required to hold on to the handlebar and control the bike will be a much lower percentage of your maximum grip strength, and as such it will be less fatiguing.

Less fatigue means less arm-pump, pain and simple. So while time spent on the road bike or indoor trainer is great for overall fitness, it should be obvious that it will do nothing for conditioning your hands or forearm muscles for the demands of mountain biking. Much in the same way that swimming won’t strengthen your feet for running. 

Less obvious is that you also need good core and leg strength, so you can support more of your body weight on the bigger, stronger musculature of your legs and less on your arms and hands. So any exercises that tax your grip strength at the same time as challenging your core and legs are great for combating arm-pump. 

Also we tend to get the worst arm-pump on the toughest parts of a trail, where we are concentrating intently, tightening up and often forgetting to breathe. 

Five exercises for eliminating arm-pump

By taking a targeted approach to training, we can hit all three issues at once with our five favourite exercises for eliminating arm-pump. 

Farmer’s carry works best with a sheep under each arm, failing that some kettlebells do the job

1. Farmers carries

If you want to really challenge your grip strength, then you need farmer’s carries in your workouts. You can use heavy dumbbells, kettlebells, sandbags with handles or dedicated farmer carry yokes.

Simply pick a weight that you can walk with for 30-45sec before your grip gives out, rest for 15sec, then repeat three times. 

Unless you’re ace at pullups and can do a dozen or so, deadhangs are more effective for building grip strength

2. Deadhangs

Pull ups are a great exercise, but if you can only do three strict pull ups, it’s not really taxing your grip strength. It’s why I prefer the deadhang.

Take an overhand grip on a bar or rings and simply hold on until your grip gives way.

For an added core stimulus raise your knees up, or if your core is strong, hang with your legs at 90 degrees to your torso and perform a hanging L sit. When your grip gives out, drop down, rest for three breaths, then grab on again, but this time with your fingers, not a fully closed grip.

When you can’t hold on any more, rest for a minute, or do a core exercise, then repeat the process three times.

Renegade rows mimic the strains mountain biking puts on your body. You can also vary it with pushups between each row

3. Renegade rows

Renegade rows look cool, but they also mirror the push/pull demands that mountain biking places on grip strength.

Grab two dumbbells and get in the push-up position, core tight, back flat. Do a push up, then in the top position, pull one of the dumbbells up to your chest while trying to prevent your torso from twisting, then lower the dumbbell to the floor. That’s one rep. Now do another push up, then raise the dumbbell in the opposite hand.

Repeat for 8-12 reps, for three sets, really focusing on squeezing the dumbbells. If you can’t do 8-12 strict push ups, drop to your knees for the push up portion then get back on your toes for the pulls.

Towel twists, also useful for drying laundry

4. Towel twists

This one couldn’t be easier to perform. Grab a bath towel, roll it up then twist your hands in opposite directions, just like you would if you were trying to wring water out of it. Twist it in one direction until you feel a lot of resistance, hold for a couple of seconds, then reverse the direction of the twisting motion. Perform for time, until you feel a burn in your forearms. 

The kneeling press will tax your forearms to the limit, just make sure you don’t go too heavy and lose control of the weight at the top

5. Bottom up half-kneeling kettle bell press

The half-kneeling KB (kettle bell) press is a great shoulder stabilisation exercise, but the bottom up version is also good for developing wrist and grip strength.

To perform the exercise, drop into a lunge position with one knee on the floor, then hold a kettlebell (bottom up) out in front of you with your elbow at 90 degrees. Press the kettlebell up to lock out and hold it there for three seconds. Return under control to the starting position and hold for another three seconds.

Perform lighter weight bottom up presses for 12-15 reps each side, then grab a heavier kettlebell in the normal rack position and press for 6-8 reps per side. Rest for two minutes between each and repeat for three sets.