Muscle Cramps During Exercise: What’s Really Causing Them
Summary
Muscle cramps during exercise are commonly misunderstood as a sign of tightness, leading people to stretch — but the real cause is often a lack of muscular strength and stability. When a muscle lacks the strength to handle a given load, it cramps as a substitute for proper stability. Addressing the root strength deficit, rather than stretching alone, is the key solution.
Key Points
- Cramping is not primarily a flexibility problem. Most people respond to cramps by stretching the affected muscle, but this targets the wrong issue.
- Cramps often signal a strength deficit. When a muscle cannot handle the load placed on it, it cramps to provide joint stability and protect against injury — an inefficient and painful compensation mechanism.
- Peak contraction exercises are high-risk for cramping. Movements that place peak tension at full contraction (e.g., Spider Curls, Barbell Hip Thrusts) are most likely to trigger cramps in weaker muscles.
- Build strength through mid-range tension exercises first. Exercises that place peak tension in the middle of the strength curve — rather than at full contraction — allow you to develop strength without provoking cramps.
- The Barbell Curl is given as an example of a better starting exercise for the bicep, since its peak tension occurs mid-range rather than at full contraction.
- Progress back to the problematic exercises. Once baseline strength is built through safer exercises, returning to the cramp-causing movements should result in significantly reduced or eliminated cramping.
- Hydration is a contributing factor. A dehydrated muscle cramps at a much higher rate and frequency, so adequate fluid intake remains important alongside strength training.
Exercise Details
Spider Curl
- Target muscles: Biceps
- Why it causes cramping: Places peak tension and peak contraction at the same point, making it high-risk for underdeveloped biceps
Barbell Curl
- Target muscles: Biceps
- Advantage over Spider Curl: Peak tension occurs in the mid-range of the movement, not at full contraction — making it a safer starting point for building bicep strength
Barbell Hip Thrust / Bridge
- Target muscles: Glutes, hamstrings
- Common problem: Peak contraction at the top of the movement can trigger hamstring cramps and glute cramps in athletes who lack sufficient strength in those muscles