Exercise-Associated Muscle Cramps

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Original Editor - Puja Gaikwad

Top Contributors - Puja Gaikwad, Habibu Salisu Badamasi, Wanda van Niekerk and Jonathan Wong  

Introduction

The specific cramping that happens during exercise is called Exercise-Associated muscle cramps (EAMC). It is defined as a syndrome of involuntary painful skeletal muscle spasms that happens during or immediately after a workout. During cramping, Skeletal or voluntary muscle contracts strongly and unable to relax resulting in EAMS. It occurs as localised muscle cramping that happens spasmodically in various exercising muscle groups, usually the calf, hamstring or quadriceps muscles. The calf muscles are the foremost commonly affected. The pain and disability that results usually limits affected limbs movement, though the condition normally resolves without intervention. Resolution can take from a couple of seconds to minutes, but the afflicted part is non-functional during this time and perhaps for some time afterwards.

Exercise-associated muscle cramping (EAMC) is a very common condition that needs medical attention during sporting events. The incidence of EAMCs increases with higher frequency, intensity and duration of the exercise, and are especially prevalent among athletes who participate in long-distance endurance events, like triathlon and marathon or ultra-marathon distance running, and it is also seen in many other sports, including basketball, the varied football codes, tennis, cricket and cycling, etc. The prevalence of EAMC has been documented for triathletes (67%) runners (roughly around 30% to 50%), rugby players (52%) and cyclists (60%) Despite the high prevalence of EAMC, its risk factors, pathophysiology, management and prevention aren't completely understood.

Risk Factors

The risk factors related to EAMC in endurance athletes include high-intensity running, long-distance running (> 30 km), subjective muscle fatigue, all of which are intense and exhaustive physical efforts. Other risk factors found were older age, a longer history of running, higher body mass index (BMI), shorter daily stretching time, irregular stretching habits, and a positive family history of cramping. Factors related to a history of EAMC included underlying chronic disease (including the cardiovascular, respiratory, gastrointestinal, and nervous system, kidney, bladder and haematological diseases), as well as cancer, allergies, regular medication use, and past history of injury. Experienced runners are also at higher risk.

Aetiology

Theories for the cause of EAMC

Altered Neuromuscular Control Theory

Because EAMC occurs in a variety of situations, environmental conditions, and populations, it is unlikely that a single factor (eg, dehydration, electrolyte imbalance, or neuromuscular factors) is responsible for causing them directly. It is more likely that EAMC is due to a combination of factors that simultaneously occur under specific physiological circumstances in each athlete.

Signs and Symptoms

EAMC can be identified clinically by acute pain, stiffness, visible bulging or knots in the muscle, and possible soreness which will occur suddenly with no warning and lasts for several days. The injured muscles often appear to be randomly involved, and as one bundle of muscle fibres relax, adjacent bundle contracts, giving the impression that the spasms wander. For example, twitches first can appear in the quadriceps and subsequently in another muscle group. Most EAMC persists for 1-3 minutes, but athletes often complain of EAMC symptoms up to eight hours after exercise. This post-exercise span of increased susceptibility to EAMC has been termed as the "cramp-prone state". EAMC may be completely debilitating although in few cases EAMC does not appear to affect athletic performance.