Cramping during exercise: why it happens and how to help

If you’ve ever had a cramp while exercising, you know how uncomfortable it is, and you probably don’t want it to happen again.

Cramps can happen in any muscle but are common in the hamstrings, feet, and even in the biceps. You may have experienced a “charlie horse” feeling in your hamstring while doing a bridge. Or maybe you’ve taken a barre class and get startling cramping in your calves/feet when you point your foot.

Let’s discuss why this happens and how to combat it. And no, the fix is not as simple as “eat more bananas.” 

Cramping during exercise can happen due to an electrolyte imbalance (potassium being one of these electrolytes, which is where the banana comes in). However, most studies show that it is actually neuromuscular mechanisms at work when cramping occurs during exercise. 

Cramping is an involuntary, uncomfortable, strong, and often lasting muscular contraction that occurs during exercise due to neuromuscular fatigue. When a muscle is overloaded and fatigued, there is a lack of communication between your central nervous system (what helps regulate a muscular contraction) and your muscles/tendons, causing an involuntary, strong muscular contraction. A cramp will often happen when your muscle is fully shortened and also contracting. You might notice this happening when you point your foot as hard as you can. The cramp happens when you are at the end range of motion. 

Let’s dissect the science behind cramping a little further for my fellow nerds. I’m going to get technical, but keep reading because I’ll be sure to break it all down. 

I’ll illustrate this phenomenon using the example of your bicep during a preacher curl. A preacher curl is similar to a bicep curl, except your humerus (upper arm bone) is propped forward on a bench or ball. This alters the force distribution from a regular bicep curl (a regular bicep curl is a great exercise, so why mess with it? But I digress), causing most of the force to be distributed while the muscle is fully shortened. This is a perfect recipe for a cramp; your muscle is near its end range while also contracting strongly.

Sometimes this cramp can happen on your first repetition, but it often happens as the muscle fatigues. This fatigue reduces inhibitory input to alpha motor neurons in the spinal cord from the golgi tendon apparatus and excitatory drive from the muscle spindles. Essentially, the input from your muscle to your spinal cord is disrupted, causing the muscle to lose controlled contraction, and it involuntarily contracts (cramps). 

This is because there is depressed signaling from the golgi tendon organs. The role of golgi tendon organs (proprioceptive organelles that live in the tendons) is to sense muscle contraction and relax the contracting muscle if it is too much for the tendon to handle. This prevents tendon damage that could be incurred from lifting something too heavy. When your golgi tendon organ has poor ability to function at the end range of motion, it cannot properly regulate the muscle contraction level, causing an inappropriate contraction rate.

You could view your golgi tendon organ as the “circuit breaker.” When the golgi tendon organ detects you are lifting something that could damage the tendon, it will send a message to your spinal cord to make the muscle relax, so you drop the weight and don’t hurt yourself. 

A cramp is your nervous system’s back up mechanism for when the circuit breaker (golgi tendon) isn’t triggered. Your nervous system isn’t receiving “validation” from the golgi tendon organ that you’re safe and not lifting something too heavy, so it overrides your voluntary muscular system with a cramp in order to keep you safe and avoid a tendon injury.

In other words, a cramp occurs because your body senses instability and doesn’t feel secure in that position. So it cramps in an attempt to gain stability and safety. 

The short term fix while you’re experiencing a cramp is to stretch the muscle immediately. If your foot cramps when you point it, passively dorsiflex your foot (pull your toes towards your knee using your hand) until it goes away—no need to keep stretching it after the cramp dissipates. If you follow me, you know that I don’t believe stretching is a permanent fix for anything. 

So what is the long-term solution to stop this from happening? 

The long term solution is to create strength and stability around the joint. Strengthening the cramping muscle itself and strengthening agonist muscles (like glutes if you get hamstring cramps) will create a more stable and well-connected joint that is less prone to cramping. Strengthening not only makes the tissue bigger, but it improves the communication between your sensory organelles (like the golgi tendon organs) and your spinal cord, creating a more resilient, connected, and keen neuromuscular system. 

Another consideration when strengthening is to choose exercises that are the most challenging in the middle range of motion. When we think about the preacher curl, the hardest part of the exercise is at the very top, when your muscle is already shortened. It also isn’t challenging the muscle in the middle range of motion enough, which is where it is the strongest and most stable. This combination is not ideal in strength training, and won’t produce the best results. 

In a regular bicep curl, on the contrary, you’ll notice that the most challenging part of the exercise is in the middle, when your elbow is at about 90 degrees and gets easier as you approach the top. This is a well-designed exercise because it’s challenging in the middle range, and feels “lighter” towards the top when the muscle is fully shortened. 

This has to do with biomechanics and is a topic for another discussion. But in summary, the more “stacked” your joints are in relation to gravity, the less work your muscles have to do to maintain the position. In a bicep curl, when you’re at the top of the motion (when your elbow is fully bent), the weight you’re holding is almost completely stacked on top of your elbow. This position requires little work from your bicep to maintain. When your elbow is at 90 degrees, the weight is far from your elbow, requiring more effort to move. 

You don’t have to understand this phenomenon to apply it. Just think about an exercise and ask yourself if it feels “hardest” as you get to the end, or if it feels “hardest” when you are in the middle of the movement. If it feels the hardest in the middle, you know you have a good exercise. If it feels hardest at the end, maybe it’s time to choose a different exercise. 

To summarize, if you are experiencing cramping with exercise, here are some tips:

1. To immediately relieve the cramp, stretch the muscle that is cramping until the cramp dissipates 
2. Choose exercises that aren’t the hardest when the muscle is the shortest. A couple of examples are:
   1. A regular bicep curl instead of a preacher curl
   2. A lateral raise on your side instead of standing
   3. A hip thrust on a bend instead of a bridge (bridges aren’t bad, but they can often induce hamstring cramps) 
3. Try moving in smaller ranges of motion, or using lighter weight
4. Use weights or cables instead of bands in muscles that are cramp-prone (bands will create the most resistance when your muscle is the shortest. As we discussed above, this is a recipe for a cramp)
5. Improve proprioceptive input by using nerve glides and mobility drills (this can be as simple as circling your ankle a few times as smooth as possible before you do a leg workout)