Muscle Cramps During Exercise: Causes, Prevention, and Treatment
- Kylie
- 7 hours ago
- 4 min read
Written by Dr Phoebe Henry - Sports Chiropractor - The Functional Physio - Cremorne
Muscle cramps are described as sudden, spasmodic, painful involuntary muscle contractions that last less than 60 seconds. Muscle cramps can occur as symptom of a range medical conditions, genetic causes, or exercise. In this blog, we will focus on exercise associated muscle cramps (EAMC) and discuss why they happen and what you can do about it!
EAMC is a relatively common condition and can affect anyone – whether you’re a weekend warrior or an elite athlete, EAMC can be disabling. They can occur during or immediately after exercise, and although EAMC are generally short-lasting, they often reoccur if activity is continued at a similar intensity, having a direct negative impact on performance. EAMC most commonly affect the calf, hamstring and quadriceps muscle groups respectively, and are often reported in endurance sports, such as ultra-marathons and triathlons. However, they are also common in AFL players, pickleball atheltes, cyclists, and other sports where a rapid change in intensity is required (such as accelerating from a jog to a sprint). This is an important consideration when asking why EAMC occur…
Historically, cramps have been blamed on dehydration, exercising in the heat, and electrolyte depletion, but these theories have now (mostly) been debunked. Recent research has helped us to understand that EAMC are more likely multifactorial and occur due to the muscle fatigue response and abnormal neuromuscular control.
Myths of exercise associated muscle cramps:
EAMC is not caused by exercising in hot conditions. EAMC can occur the heat,but can also occur in cold conditions. Additionally, cooling the body and localised muscle cooling during cramping has not been shown to relieve it.
Excessive sweating/sodium depletion/dehydration is not the predominant cause of EAMC. Studies have shown that athletes suffering EAMC were not dehydrated, nor did they show disturbances in serum electrolyte (sodium) concentration
Low sodium concentration in the blood (hyponatraemia) may be associated with generalised skeletal muscle cramping at rest (but not associated with EAMC). The mechanism of EAMC is more likely due to the muscle fatigue response
Why and how does a fatigued muscle cause EAMC?
To understand this, it’s important to understand two basic principles behind how a muscle works:
Golgi Tendon Organ (located within a tendon): sense when a tendon is under tension. Messages from the Golgi Tendon Organ inhibit (or stop) muscle activation.
Muscle Spindles (located within the muscle belly): detect change in the length of a muscle – they signal muscles to contract
When a muscle becomes fatigued, it’s theorised that there is increased input from muscle spindles, but decreased input from Golgi Tendon Organs. Put simply, EAMC occur when Golgi Tendon Organs cannot stop the over-activity of muscle spindles, causing the muscle to contract uncontrollably (and very painfully). Knowing about all this physiology is important because it can instruct us how we can best treat and prevent EAMC.
So, what works for exercise induced muscle cramps?
Passive stretching is the most effective technique to provide symptomatic relief from a cramp. This is because when we stretch a muscle, we increase the Golgi Tendon Organ’s inhibitory role. Basically, stretching sends a message via our nervous system to stop a muscle from contracting. Stretching should be held for 10-20 seconds to initially stop the cramp. Some research suggests that keeping the muscle in a lengthened position for a period of up to 20 minutes is best to prevent the cramp from recurring (eg for a hamstring cramp, sit with the leg out straight in front of you)
Pickle Juice! Yep, Pickle juice is gaining in popularity for its ability to instantly stop muscle cramping. Pickle juice is suggested to work by triggering a neural reflex in the back of the throat, with the acidity signalling the nervous system to stop the muscle cramping. If you’re put off by drinking the pickle juice, you can gargle it around in your mouth for 20-30 seconds then spit it out, as this will still trigger the reflex.
Contracting the opposite muscle group (eg. quadriceps if hamstring cramp or ankle dorsiflexors if calf cramp) can also provide immediate relief from a cramp
Because the predominate cause of EAMC is fatigue, addressing general conditioning and improving endurance should be the priority for reducing EAMC risk
Plyometric and eccentric strength training have been shown to improve neuromuscular control, which may also reduce the risk of EAMC
There is low level evidence for the use of magnesium and sodium supplementation to prevent EAMC, so you can ditch the salt tablets!
References:
Schwellnus, M. P. (2009). Cause of exercise associated muscle cramps (EAMC)—altered neuromuscular control, dehydration or electrolyte depletion?. British journal of sports medicine, 43(6), 401-408.
Minetto, M. A., Holobar, A., Botter, A., Ravenni, R., & Farina, D. (2011). Mechanisms of cramp contractions: peripheral or central generation?. The Journal of physiology, 589(23), 5759-5773.
Garrison, S. R., Allan, G. M., Sekhon, R. K., Musini, V. M., & Khan, K. M. (2012). Magnesium for skeletal muscle cramps. Cochrane Database of Systematic Reviews, (9).
Nelson, N. L., & Churilla, J. R. (2016). A narrative review of exercise‐associated muscle cramps: Factors that contribute to neuromuscular fatigue and management implications. Muscle & nerve, 54(2), 177-185.
Shang, G., Collins, M., & Schwellnus, M. P. (2011). Factors associated with a self-reported history of exercise-associated muscle cramps in Ironman triathletes: a case–control study. Clinical Journal of Sport Medicine, 21(3), 204-210.
