Cramps aren’t a hydration mystery; they’re a neural control problem under fatigue. Here’s the science and the playbook that actually works.
Myth: Cramps Come From Salt or Dehydration
The dehydration–salt loss story is tidy and marketable. Still, modern endurance research shows athletes who cramp and those who don’t have no meaningful differences in blood sodium, potassium, or hydration during competition. Sweat is hypotonic relative to plasma, which means that sweating tends to raise plasma sodium levels, rather than lower them.
About Those “Electrolyte Scare” Claims
- Hyponatremia (low blood sodium) is real but rare in racing and driven by over-drinking, not “not enough salt.”
- Hypernatremia (excess sodium) in endurance settings is extremely rare to virtually nonexistent and not a credible risk from skipping electrolyte mixes. Treat “you’ll get hypernatremic without our product” as fear marketing.
Electrolyte products can be useful for taste and comfort, but they don’t “cramp-proof” you.
What’s Really Happening: A Neural Misfire
Exercise-associated muscle cramps are neuromuscular. Under fatigue, the balance between the two reflex sensors breaks down:
- Muscle spindles (length sensors) become overexcited → more contraction.
- Golgi tendon organs (tension sensors) go underactive → less relaxation.
Result: the motor nerve overfires and the muscle locks; a neural control failure, not a fluid shortage.
When & Where Cramps Strike
- Racing harder than you’ve trained (pacing errors).
- Local fatigue in bi-articular muscles: calves (gastrocnemius), hamstrings, rectus femoris.
- Shortened positions: seated pedalling, toe-pointing in swim kick, steep descents.
How to Stop a Cramp, Fast
- Ease effort for 1–3 minutes. Reduce motor-neuron firing.
- Use a mouth “sting”. A small shot of pickle juice, vinegar, mustard, or wasabi can stop a cramp in ~30–60s by triggering an oral–brainstem reflex that inhibits the cramping nerve.
- Sustained stretch (20–30s). Loads the Golgi tendon organ and restores relaxation.
How to Cramp-Proof Your Training
- Eccentric strength (5-sec lowers): calves, quads, hamstrings; add split squats, step-downs.
- Specific conditioning: downhills, big-gear climbs, and race-pace blocks.
- Pacing discipline: start conservative; cap surges.
- Fuel with carbs: delay neural and local fatigue.
- Hydrate to thirst: avoid over-drinking; keep salt only if it consistently helps you.
TL;DR: The MetriqFuel Summary
Cramp = neural fatigue glitch, not a salt shortage.
Fear-based electrolyte marketing overstates risk, especially “hypernatremia.”
Manage effort. Build fatigue resistance. Use mouth-sting + stretch for fast relief.