We are past the training camp months now and weeks into our respective football seasons. Teams have surmounted a number of grueling practices and physically taxing competitive games to declare themselves in “football shape.” At this point of the football season, teams are beginning to see cooler temperatures as Fall begins to make its presence known. By now, trainers, coaches, and players are fully aware and familiar with the rising intensities associated with football competitions along with the increasing rates of injury and also the consistent presence of athletes number one foes: exercise associated muscle cramps. In my years in the NFL I have witnessed the incredibly debilitating effect in which this seemingly innocuous physiological phenomenon can inflict to some of the most invulnerable football stars. It is a consistent challenge for training staffs and coaches across the nation who are not only concerned for both the health and well-being of their athletes but also their performance potential.
Exercise associated muscle cramps (EAMC) can seize athletes during potentially vital moments such as the final quarter or period to end a game. They can limit the contributions of key players to their own performance and a team’s overall success. Exercise associated muscle cramps can also cause injury. Thus, it should be no surprise that muscle phenomenon can be costly for teams, coaches, training staffs and players. Yet with the rise of science, technology, and financial spending on the development and healthcare of our athletes, EAMC continues to thrive in sports. Even more perplexing is the fact that the cause, prevention and treatment of EAMC remains poorly understood, controversial and mired in conventional methods of practice. In other words, the understanding and methods of treatment for one of athlete’s and teams’ most challenging foes is limited, varied and potentially ineffective.
Why you should care to know about recent developments associated with EAMC
As we continue to delve deep into our respective occupations associated with athletic performance it is always important to reevaluate our approach to our work and the many challenges we face in caring for and developing our athletes. This task is even more important in the face of scientific growth. When we acknowledge and/or discuss developments in science, we can change the pillars of our foundation or reaffirm them. The ultimate result, however, is always, a greater platform for allowing our athletes and teams to succeed under great care. With respect to recent developments in science in addition to the care and success of our team and athletes I have centered on investigating the cause and potential strategies for the prevention and treatment of EAMC. This investigation provides us the opportunity to dispel previous established and/or ineffective frames of thought, enables us to step away from conventional practices and helps unify our approach to improving athletic care and performance.
EAMC Affects Individuals Across Various Levels and Age
While exercise associated muscle cramps is a relatively common physiological phenomenon, it is also multifaceted and complex in nature. EAMC is understood as a painful, spasmodic, and involuntary contraction of skeletal muscle that occurs during or immediately after exercise (Nelson & Churilla, 2016). These muscle cramps can occur in healthy individuals who have no underlying metabolic, neurological, or endocrine pathology (Nelson & Churilla, 2016).
It is a muscular phenomenon which affects athletes across various levels, ages and sports as well as those who engage in physical labor and recreational activity. EAMC is among the most common conditions that require medical intervention, either during or immediately upon completion of athletic events (Nelson & Churilla, 2016). Investigators of this condition report that 95% of physical education students have had some form of spontaneous muscle cramps in their lifetimes with 26% experiencing cramps after exercise (Miller, Stone, Huxel & Edwards, 2010).
As further evidence for the wide ranging impact of this common affliction, EAMC was reported by investigators to affect more than half of triathletes in a variety of training conditions in a 1990 study (Miller, Stone, Huxel, & Edwards, 2010). While investigators continue to acknowledge the pervasiveness of EAMC within sport and recreational activity the cause for it’s occurrence remains unknown and controversial (Miller, Stone, Huxel, & Edwards, 2010). As a result, the incidence of EAMC continues to be a challenge for athletes, coaches, training and medical staffs across the nation who have had experience with this potentially debilitating condition
Latest Theories on the Cause of EAMC
Recent observations in the field of neuromuscular function is beginning to provide new information as to the potential cause of this phenomenon. Along with this developing insight are new strategies, tools and forms of treatment that can be used to help relieve, alleviate and potentially prevent EAMC from occurring in physically active individuals. As we continue to address the cause and treatment of EAMC from a wide range of perspectives we may begin to understand unknown factors important to physiological function and its development. This knowledge can potentially decrease EAMC occurrence in sports.
The “Dehydration and Electrolyte Imbalance Theory” as cause of EAMC
It is useful to understand past methodology in treatment and prevention of EAMC in order to develop a greater understanding of etiology and to produce more effective models of treatment. EAMC is currently understood as a complex physiological activity which can be related to a multitude of factors that includes dehydration, electrolyte imbalance and factors related to neuromuscular dysfunction and or fatigue. However, previous investigators and sport medicine practitioners have attributed EAMC solely to factors related to hydration and electrolyte imbalance.
The “dehydration–electrolyte imbalance” theory was a popular and commonly understood theory for the cause of EAMC among health care professionals (Miller, Stone, Huxel, & Edwards, 2010). This theory explains that during physical activity the extracellular fluid compartment outside the cell becomes increasingly contracted due to sweating which leads to a loss of interstitial volume. This process when combined with excessive sweating can lead to deficits in micronutrients such as sodium, calcium, magnesium, chloride, and potassium (Miller, Stone, Huxel, & Edwards, 2010). The end result is a mechanical deformation of nerve endings and an increase in the surrounding ionic and neurotransmitter concentrations which leads to hyperexcitable motor nerve terminals, spontaneous discharge and the potential occurrence of EAMC (Miller, Stone, Huxel, & Edwards, 2010). In other words, sweating and corresponding loss of micronutrients and electrolytes cause physical and functional havoc to our muscular system.
Despite the popularity of this theory amongst practitioners, scientific evidence for its relationship to the cause of EAMC is lacking. Dr. Nicole Nelson states in a 2016 review that hydration status and electrolyte concentrations seem unrelated to the cause of EAMC as it is often relieved by stretching of the affected muscles or by activation of the Golgi tendon organs (Nelson & Churilla, 2016). In her review, she also adds that indicators of dehydration status such as plasma volume in runners with EAMC were not significantly different from those of runners without EAMC (Nelson & Churilla, 2016). Growing research has produced a number of limitations to the dehydration electrolyte imbalance theory.
For instance, it is proposed that if EAMC were due to dehydration, the simple cure would be fluid replacement. This belief lies in contrary to observations from researchers at the University of North Carolina at Charlotte. In this study subjects ingested carbohydrate-electrolyte fluids at a rate that matched sweat loss. However, results showed that EAMC still occurred in 69% of athletes despite the carbohydrate and electrolyte intervention (Jung, Bishop, Al-Nawwas & Dale, 2005).
The “Altered Neuromuscular Theory” as cause for the occurrence of EAMC
While EAMC may appear in the presence of significant electrolyte and/or fluid losses during exercise there are a number of variables which can impact exercise associated muscle cramps. These factors include the accumulation of metabolites, intensity of exercise, and various neuromuscular mechanisms related to fatigue. Doctor Martin Schwellnus is widely known for popularizing the “Altered Neuromuscular Control Theory” which suggests that EAMC results from altered reflex control mechanisms in response to neuromuscular fatigue. Specifically, this theory explains that muscle overload and fatigue create an imbalance of the excitatory drive from muscle spindles and the inhibitory drive from the Golgi tendon organ. This imbalance results in an increase in excitatory drive to the alpha motor neuron, which ultimately produces a localized cramp (Nelson & Churilla, 2016). In other words, intense activity and fatigue disrupt the communication that takes place within our neuromuscular system.
Observational investigations and experimental studies centered on cause and treatment of EAMC have continued to support the “Altered Neuromuscular Theory.” Evidence for this theory is supported by the finding that athletes with a history of EAMC are more likely to cramp during or shortly after exercise than those who had no history of EAMC (Schwellnus, Drew & Collins, 2011). Furthermore, investigators also report that triathletes who experienced EAMC while participating in an Ironman event, or in the 6 hours after the race, had a significantly higher reported history of EAMC compared with the triathletes who did not cramp (Nelson & Churilla, 2016). These observations are part of a number of scientific findings which suggest that a history of EAMC is a strong predictor for its manifestation in certain individuals. Growing research lends greater support to neuromuscular dysfunction as a potential cause relative to dehydration and electrolyte imbalance. In addition, methods of managing EAMC have recently begun to center more closely on factors related to neuromuscular function and fatigue and produced positive results in support for the Altered Neuromuscular Theory.
Furthermore, Dr Karen Schwabe et al. reported in a 2014 study that triathletes categorized as cramp-prone had faster overall finishing times compared with those categorized as non-crampers (Schwabe, Schwellnus, Derman, 2014). The finding reflected in this study suggested a role of muscle fatigue during the end of triathlons as cause for the occurrence of EAMC.
As research continues to reveal various methods for managing and treating EAMC we also develop a greater perspective to our understanding of neuromuscular function during exercise as well as factors central to fatigue. In the next post we will investigate various strategies that can be useful for both the treatment and prevention of exercise associated muscle cramps.
Top Three Things you should know about Exercise Associated Muscle Cramps
Scientific Evidence Is limited in support for the Dehydration and Electrolyte imbalance Theory and Exercise Associated muscle Cramps.
Exercise associated muscle cramps is understood as a complex physiological activity which can be cause and or related to a multitude of factors that includes but is not limited to dehydration and electrolyte imbalance. In others words, if your treatment and prevention protocol for exercise associated muscle cramps relies solely on hydration and electrolyte intake you may be missing the target. Don’t just take my word for it. Dr. Martin P Schwellnus one of the foremost experts on muscle cramps notes that scientific evidence for the dehydration and electrolyte depletion as a cause for muscle cramps is limited (Schwellnus, 2009). More importantly, the physiological mechanisms behind dehydration and electrolyte depletion does not offer scientific explanation for the treatment and/or management of exercise associated muscle cramps.
Neuromuscular function is the foundation for the leading theory on the cause of Exercise Associated Muscle Cramps
“Altered neuromuscular control” or factors associated with muscle fatigue is the leading theory behind the mechanisms which cause exercise associated muscle cramps (Schwellnus, 2009). Researchers note that muscles that cross two joints (with greater potential for compensation and fatigue) during running activity such as the calves and hamstrings are at greater risk for muscle cramps.
EAMC are likely to occur in certain athletes more than others.
Evidence for this theory is supported by the finding that athletes with a history of EAMC were more likely to cramp during or shortly after exercise than those who had no history of EAMC (Schwellnus, Drew & Collins, 2011). Furthermore, investigators also report that triathletes who experienced EAMC while participating in an Ironman event, or in the 6 hours after the race, had a significantly higher reported history of EAMC compared with the triathletes who did not cramp (Nelson & Churilla, 2016).
Jung, A.P., Bishop, P.A., Al-Nawwas, A., Dale, R.B. (2005). Influence of Hydration and Electrolyte Supplementation on Incidence and Time to Onset of Exercise-Associated Muscle Cramps, Journal of Athletic Training.40(2), 71–75
Miller, K. C., Stone, M. S., Huxel, K. C., & Edwards, J. E. (2010). Exercise-Associated Muscle Cramps: Causes, Treatment, and Prevention. Journal of Sports Health, 2(4), 279–283.
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.
Schwabe, K., Schwellnus, M. P., Derman, W., Swanevelder, S., & Jordaan, E. (2014). Less experience and running pace are potential risk factors for medical complications during a 56 km road running race: a prospective study in 26 354 race starters—SAFER study II. British Journal of Sports Medicine, 48(11), 905-911.
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.
Schwellnus M.P., Drew, N., Collins, M. (2011). Increased running speed and previous cramps rather than dehydration or serum sodium changes predict exercise-associated muscle cramping: a prospective cohort study in 210 Ironman triathletes. British Journal of Sports Medicine,( 45), 650–656.
Dan Liburd is in his ninth season as a NFL Strength and Conditioning Coach. Liburd has experience in designing, implementing and supervising Strength and conditioning programs for various athletic populations. Liburd also has experience in designing and overseeing team nutrition and dietary programs. Liburd is a Certified Strength and Conditioning Specialist who earned a Bachelor’s degree in Exercise Science from Boston University, A Master’s of Science from Canisius College in Health and Human Performance and is currently working towards a Phd in Health and Human Performance at Concordia University Chicago. Liburd has worked with several professional teams such as the Buffalo Bills and held various positions in Collegiate Strength and Conditioning programs. He has worked with the Boston University Terriers, Springfield College Pride, American College Yellow Jackets and held positions at Mike Boyle Strength and Conditioning as well as Peak Performance Physical Therapy. For more articles please checkout http://www.doyou-live.com