Trail Running Cramps: What If the Problem Isn't Just Lack of Salt?

Trail runner suffering from muscle cramps

Kilometer 60, you're feeling good. Then your calf locks up suddenly. Universal reflex: pop a salt tablet. Yet, science tells a different, and far more useful, story for your progress.

Learn to read what your cramps are trying to tell you and how to prevent them effectively.

Preventing muscle cramps in trail running

Understanding the Real Origin of Cramps

A Cramp Is Born in the Nervous System

A cramp is born in the nervous system. When a muscle reaches an unfamiliar level of fatigue, the motor neuron that controls it becomes overexcitable: contraction overrides relaxation, and the muscle locks up. That's why you can be perfectly hydrated, have taken your electrolytes… and still cramp.

This understanding changes everything. The problem is not primarily biochemical (dehydration, sodium), but neurological and muscular: it's unfamiliar neuromuscular fatigue that triggers the cramp.

Preventing Cramps Through Specific Training

Replicate Your Race's Demands

Prepare your muscles for the exact demands of race day. Does your race have 3,000 meters of descent? Practice descending. Are there 20% grades? Get your calves used to those inclines. Using poles for ten hours? Go out with your poles.

Add two eccentric strengthening sessions per week, and you'll push back the moment your muscle gives out. Eccentric work (the braking phase of movement) specifically prepares muscle fibers for the demands of descents and changes in intensity.

Analyze and Adapt Your Training

Your cramps are data. Always after a long descent? Always the same muscle? Only when you start too fast? Note the context every time.

An identified limitation becomes a limitation that you train. This analytical approach transforms every cramp into actionable information for your next training cycle.

Anti-Cramp Strategy: Complete Action Plan

During Preparation

  • Identify the specific demands of your race: long descents, steep climbs, pole usage, effort duration
  • Replicate these demands in training progressively
  • Integrate 2 strengthening sessions per week: eccentric work for quadriceps, calves, and hamstrings
  • Document your sessions to track your progress

On Race Day

  • Start at a sustainable pace from the beginning
  • Drink to thirst, without forcing hydration
  • Adjust sodium intake for heat, without excess
  • If a cramp occurs: slow down immediately, stretch slowly for 20 to 30 seconds, then resume at a slightly reduced pace

After the Race

Systematically note:

  • The affected muscle
  • The precise moment (mileage, cumulative elevation)
  • The type of terrain
  • The pace at the moment of the cramp

Your next training block directly stems from this. This information allows you to precisely target weaknesses to strengthen.

Specific training to prevent cramps in trail running

A Question for Progress

Can you name the muscle, the exact moment, and the context of your last cramp during a race?

If the answer is no, your training log awaits a new column. This discipline of observation transforms cramps from unfortunate accidents into resolved problems.

— Antoine, Baptiste, and Etienne from TRL