Why do muscles cramp?

We’ve all been there, whether it’s during or after sport, sitting on the couch or during the night, nice as you like, then BOOM something cramps up! You hobble around sometimes screaming in pain from the shock of it all or are ripped from a delightful sleep and try to stretch off or grab the offending muscle until the pain subsides!

What is skeletal muscle cramp?


  • Powerful involuntary skeletal muscle contraction during or immediately after activity, with no underlying metabolic, neural or endocrine pathology.


  • 12-year study of marathon medical issues showed only 6.1% athletes suffered with cramp, meaning only 1.2/1000 of participants.
  • Family history of cramp can predispose.
  • Men are more likely to suffer exercise cramp over women due to higher numbers of fast twitch muscle fibres.
  • Studies have shown correlations between higher exercises intensity and duration will result in increased cramp and individuals who cramp more are predisposed to more tendon and ligament injuries.

Theories / The Science Bit –

  • Thought to be due to dehydration or electrolyte imbalance.
  • Increased sweating causes the extracellular fluid compartment to contract, leading to a loss of interstitial volume.
  • Increased sweating causes reduced sodium, calcium, magnesium, chloride and potassium, this causes mechanical defects to nerve endings and increased ionic and neurotransmitter concentration and thus hyperexcitable motor nerve units and spontaneous discharge, leading to cramp.
  • All studies supporting these theories have shown no cause and effect, relating to cramps.

Ineffective Treatments –

  • Lack of evidence to support the efficacy of salt tablets and magnesium supplements.
  • Quinine reduces night and idiopathic cramps, however is now prohibited in the USA as it can reduce blood platelet levels.

Effective Treatment –

  • Re-educate agonist muscles i.e. – strengthen weak muscles around the cramping ones, for example: hamstrings generally cramp due to overloading and compensating for Glute Max weakness.
  • K-tape and compression garments cause skin convolutions and increase local blood flow.
  • Massage therapy to reduce neural excitability.
  • Pickle juice (1ml per KG body weight) = salt and acetic acid to trigger inhibitory reflex.
  • Stretching is still the most effective way to relive fatigue induced muscle cramps.


Source – Physiotutors


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