Secondary Logo

Institutional members access full text with Ovid®

Share this article on:

Factors Associated With a Self-Reported History of Exercise-Associated Muscle Cramps in Ironman Triathletes: A Case–Control Study

Shang, Gavin MBBCh, MPhil*; Collins, Malcolm PhD*†‡; Schwellnus, Martin P MBBCh, MSc(Med), MD*‡

Clinical Journal of Sport Medicine: May 2011 - Volume 21 - Issue 3 - p 204-210
doi: 10.1097/JSM.0b013e31820bcbfd
Original Research

Objective: Exercise-associated muscle cramping (EAMC) is a common medical condition in endurance athletes. The exact cause of and risk factors for EAMC are still being investigated. The main objective of this study was to investigate factors that are associated with a self-reported history of EAMC in Ironman triathletes.

Design: Case-control study.

Setting: Field study at an international Ironman Triathlon.

Participants: Triathletes participating in an Ironman Triathlon were recruited as subjects.

Assessment of Risk FactorsA previously validated prerace questionnaire was completed by 433 subjects who were divided into subjects who reported a history of EAMC (EAMC group = 216) and those who no reported history of EAMC (CON group = 217).

Main Outcome Measures: Training, anthropometric, injury and performance, and other variables that were related to the history of EAMC.

Results: Compared with the CON group, triathletes in the EAMC group were significantly taller and heavier, had faster Ironman race times despite being of similar caliber (past personal best times), and predicted and achieved a faster overall time during the Ironman Triathlon. There was an association among a positive family history for EAMC, a history of tendon and/or ligament injuries, and a self-reported history of EAMC.

Conclusions: There is evidence from this study that a history of EAMC is associated with (1) exercising at a higher intensity during a race that may result in premature muscle fatigue, (2) an inherited risk (positive family history), and (3) a history of tendon and/or ligament injury.

From the *UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa; †South African Medical Research Council, Parow, Cape Town, South Africa; and ‡International Olympic Committee Research Centre, Clinical Sport and Exercise Medicine Research Group, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.

Submitted for publication August 17, 2010; accepted December 15, 2010.

Funding for this study was provided in part by funds from the Discovery Health, the South African Medical Research Council and the University of Cape Town Staff Research Fund, and the International Olympic Committee Research grant to the Clinical Sports Medicine Group of the UCT/MRC Research Unit for Exercise Science and Sports Medicine of the University of Cape Town.

The authors report no conflict of interest.

Corresponding Author: Martin P. Schwellnus, MBBCh, MSc(Med), MD, UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, South Africa, 3rd Floor, Sports Science Institute of South Africa, Boundary Rd, Newlands, Cape Town 7700, South Africa (martin.schwellnus@uct.ac.za).

© 2011 Lippincott Williams & Wilkins, Inc.