You are halfway through a race, a match, or a hard training session when it happens: a sudden, involuntary contraction that grips a muscle and will not let go. Exercise-associated muscle cramps (EAMC) affect athletes across every sport and every level. But what actually causes them? The answer is more nuanced than most people think.
The Two Competing Theories
1. The Dehydration and Electrolyte Theory
The traditional explanation holds that cramps are caused by fluid loss and depleted electrolytes, particularly sodium, potassium, and magnesium. The idea is that sweating reduces the volume of the interstitial fluid surrounding muscles, which increases pressure on nerve endings and triggers involuntary contractions.
There is some evidence for this: athletes who sweat heavily and those who lose large amounts of sodium in their sweat do appear to cramp more frequently. However, this theory has significant gaps. It cannot explain why cramps often affect only one muscle group rather than the whole body, why they occur in cool conditions where dehydration is minimal, or why stretching (which does not restore fluids) provides immediate relief.
2. The Neuromuscular Fatigue Theory
The more recent and increasingly supported theory is that EAMC are caused by altered neuromuscular control. During prolonged or intense exercise, the normal balance between excitatory and inhibitory signals to the muscles breaks down.
Specifically, muscle spindles (which sense stretch and drive contraction) become overactive, while Golgi tendon organs (which normally inhibit excessive contraction) become less responsive. This creates a net increase in alpha motor neuron firing, leading to uncontrolled, involuntary contraction.
This theory explains why cramps tend to affect specific muscles (those under the most load), why they occur more often late in exercise (when fatigue is greatest), and why stretching provides rapid relief (it stimulates the Golgi tendon organs to send inhibitory signals).
The Emerging Consensus
Contemporary research suggests that both theories have merit and that EAMC likely result from multiple factors occurring simultaneously. A 2022 evidence-based review in the Journal of Athletic Training concluded that neuromuscular fatigue and altered spinal reflex activity are key mechanistic contributors, while acknowledging that electrolyte status and hydration may play a modulating role.
In practical terms, this means there is no single cause and no single prevention strategy. Athletes need a multi-pronged approach.
Risk Factors for Exercise-Associated Muscle Cramps
- History of cramping: if you have cramped before, you are more likely to cramp again.
- Increased exercise intensity or duration beyond what you are trained for.
- Hot and humid conditions (accelerates fatigue and fluid loss).
- Inadequate conditioning: muscles that are not prepared for the demands placed on them.
- Poor pacing: starting too fast depletes resources and accelerates fatigue.
- Older age: cramp susceptibility increases with age.
- High sweat rate and high sodium concentration in sweat.
Prevention Strategies
- Train specifically for the demands of your event (duration, intensity, terrain).
- Include strength and conditioning work, particularly eccentric exercises.
- Fuel and hydrate properly before and during exercise.
- Pace conservatively, especially in the early stages of longer events.
- Warm up thoroughly and include dynamic stretching.
- Acclimatise to heat if racing in warm conditions.
When Cramps Strike: Fast-Acting Solutions
Despite best prevention efforts, cramps can still occur. When they do, the fastest evidence-based intervention is acetic acid delivered via the oropharyngeal route. Pickle juice containing acetic acid activates TRP channels in the mouth and throat, triggering a vagal reflex that inhibits the overactive motor neurons causing the cramp. This works within 30 to 90 seconds.
PickleUp shots are designed for exactly this purpose: a portable, pre-measured dose of acetic acid that athletes can carry and use mid-event. Whether you run, ride, swim, or play on a pitch, having a rapid cramp intervention to hand is a practical edge.
