What are muscle cramps?
A muscle cramp occurs when a muscle suddenly becomes forcibly and uncontrollably shortened and locked into a painful spasm. A spasm occurs when a muscle, or even a few fibres of a muscle contract involuntarily (ie without you consciously willing it). If the spasm is forceful and sustained, it becomes a cramp. A muscle cramp is thus defined as an involuntarily and forcibly contracted muscle that does not relax. This causes a visible or palpable hardening of the involved muscle. Muscle cramps can affect any skeletal muscles in the body, but are most common in muscles or muscle groups that span two joints. However, in addition to these areas, cramps can also affect the hands, tummy muscles (abdominals), the muscles around the rib cage, and the feet and toes. Muscle cramps can last anywhere from a few seconds to (in severe cases) 15 minutes or longer. A muscle cramp in a particular location may also recur multiple times until it finally goes away. In severe cases, an episode of muscle cramping can even lead to post-cramping muscle soreness, akin to delayed onset muscle soreness (DOMS).
What causes muscle cramps?
Despite being a very common condition that affects nearly everybody at some time in their life, the exact causes of cramps remain something of a mystery. What we do know is that cramping occurs when the normal mechanisms controlling muscle contraction and relaxation become temporarily impaired. These control mechanisms involve the electrical stimulation of muscle fibres (motor unit firing) and subsequent deactivation (relaxation). There are a number of physiological requirements for efficient muscle contraction and relaxation and if any one of these requirements is not met, muscle cramping becomes more likely.
These requirements include:
• Adequate hydration and proper and adequate levels of the electrolyte minerals (together, they’re needed for motor unit firing and relaxation);
• Well-trained muscles that are both supple and sufficiently conditioned for the exercise being undertaken (muscle cramps are much more likely to occur in muscles that are unused to vigorous training);
• Adequate rest and recovery; we know that muscles are much more likely to cramp when fatigued.
Despite the lack of unequivocal evidence however, most scientific authorities agree that any nutritional cramp-prevention strategy should aim to address three important areas:
1. Maintaining adequate hydration – because all electrical signalling activity in the muscles takes place in an aqueous (water) environment and even small shortfalls in hydration levels could lead to impaired electrical signalling and an increased risk of cramping;
2. Ensuring adequate dietary intake of the electrolyte minerals sodium and potassium because they’re involved in conducting electrical signals to/from muscles, and calcium and magnesium, which are essential for the contraction and relaxation of muscle fibres;
3. Replenishing energy in the form of carbohydrate – because even small drops in the level of stored muscle carbohydrate (glycogen – your body’s premium fuel for exercise) can lead to increased fatigue, which may in turn increase the risk of muscle cramps.