Cramps caused by effort, not dehydration and electrolyte shortage
PainSci summary of Schwellnus 2011?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focussed on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided at the bottom of the page, as often as possible. ★★★★☆?4-star ratings are for bigger/better studies and reviews published in more prestigious journals, with only quibbles. Ratings are a highly subjective opinion, and subject to revision at any time. If you think this paper has been incorrectly rated, please let me know.
Blood samples from 210 Ironman triathletes were checked for electrolytes and other signs of hydration status. 43 had suffered cramps. There was no significant differences between the crampers and the non-crampers in any of the pre-testing or post-testing. The shocking conclusion? Dehydration and electrolyte shortage don’t cause cramps — intense effort does. “The results from this study add to the evidence that dehydration and altered serum electrolyte balance are not causes for EAMC.” A nice myth-mangler of a study!
BACKGROUND: Despite the high prevalence of exercise-associated muscle cramping (EAMC) in endurance athletes, the aetiology and risk factors for this condition are not fully understood.
AIM: The aim of this prospective cohort study was to identify risk factors associated with EAMC in endurance triathletes.
METHODS: 210 triathletes competing in an Ironman triathlon were recruited. Prior to the race, subjects completed a detailed validated questionnaire and blood samples were taken for serum electrolytes. Immediately before the race, pre-race body weight was obtained. Body weight and blood samples for serum electrolyte concentrations were obtained immediately after the race. Clinical data on EAMC experienced during or immediately after the race were also collected.
RESULTS: 43 triathletes reported EAMC (cramping group) and were compared with the 166 who did not report EAMC (non-cramping group). There were no significant differences between groups in any pre-race-post-race serum electrolyte concentrations and body weight changes. The development of EAMC was associated with faster predicted race times and faster actual race times, despite similarly matched preparation and performance histories in subjects from both groups. A regression analysis identified faster overall race time (and cycling time) and a history of cramping (in the last 10 races) as the only two independent risk factors for EAMC.
CONCLUSION: The results from this study add to the evidence that dehydration and altered serum electrolyte balance are not causes for EAMC. Rather, endurance runners competing at a fast pace, which suggests that they exercise at a high intensity, are at risk for EAMC.
These six articles on PainScience.com cite Schwellnus 2011 as a source:
- PS Trigger Points & Myofascial Pain Syndrome — A guide to the unfinished science of muscle pain, with reviews of every theory and self-treatment and therapy option
- PS Save Yourself from Muscle Strain! — Muscle strain (pulled muscle) and muscle pain explained and discussed in great detail, plus every imaginable treatment option
- PS Water Fever and the Fear of Chronic Dehydration — Do we really need eight glasses of water per day?
- PS Delayed Onset Muscle Soreness (DOMS) — The biological mysteries of “muscle fever,” nature’s little tax on exercise
- PS My Athletic Injuries — A journal of my experiences with injuries acquired while running, cycling and hiking and playing ultimate for fifteen years
- PS Cramps, Spasms, Tremors & Twitches — The biology and treatment of unwanted muscle contractions