PainSci summary of Schwellnus 2011?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focused 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!
original abstract†Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.
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 seven 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 Post-Exercise, Delayed-Onset Muscle Soreness — The biology & treatment of “muscle fever,” the deep muscle soreness that surges 24-48 hours after an unfamiliar workout intensity
- PS Does Epsom Salt Work? — The science of Epsom salt bathing for recovery from muscle pain, soreness, or injury
- 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
This page is part of the PainScience BIBLIOGRAPHY, which contains plain language summaries of thousands of scientific papers & others sources. It’s like a highly specialized blog. A few highlights:
- A Bayesian model-averaged meta-analysis of the power pose effect with informed and default priors: the case of felt power. Gronau 2017 Comprehensive Results in Social Psychology.
- The neck and headaches. Bogduk 2014 Neurol Clin.
- Agreement of self-reported items and clinically assessed nerve root involvement (or sciatica) in a primary care setting. Konstantinou 2012 Eur Spine J.
- Effect of NSAIDs on Recovery From Acute Skeletal Muscle Injury: A Systematic Review and Meta-analysis. Morelli 2017 Am J Sports Med.
- Association of Spinal Manipulative Therapy With Clinical Benefit and Harm for Acute Low Back Pain: Systematic Review and Meta-analysis. Paige 2017 JAMA.