Underlying Chronic Disease, Medication Use, History of Running Injuries and Being a More Experienced Runner Are Independent Factors Associated With Exercise-Associated Muscle Cramping: A Cross-Sectional Study in 15778 Distance Runners

Background: Exercise-associated muscle cramping (EAMC) is a significant medical complication in distance runners, yet factors associated with EAMC are poorly documented. Objective: To document risk factors associated with EAMC in runners. Design: Cross-sectional study. Setting: Two ocean races (21.1 km, and 56 km). Participants: Fifteen thousand seven hundred seventy-eight race entrants. Methods: Participants completed a prerace medical history screening tool including: training, cardiovascular disease (CVD), risk factors for, and symptoms of CVD, history of diseases affecting major organ systems, cancer, allergies, medication use, and running injury. Runners were grouped as having a history of EAMC (hEAMC group = 2997) and a control group (Control = 12 781). Results: Independent factors associated with a higher prevalence ratio (PR) of hEAMC were any risk factor for CVD (PR = 1.16; P = 0.0002), symptoms of CVD (PR = 2.38; P < 0.0001), respiratory disease (PR = 1.33; P < 0.0001), gastrointestinal disease (PR = 1.86; P < 0.0001), nervous system or psychiatric disease (PR = 1.51; P < 0.0001), kidney or bladder disease, (PR = 1.60; P < 0.0061), haematological or immune disease (PR = 1.54; P = 0.0048), cancer (PR =1.34; P = 0.0031), allergies (PR =1.37; P < 0.0001), regular medication use (PR = 1.80; P < 0.0001), statin use (PR = 1.26; P = 0.0127), medication use during racing (PR = 1.88; P < 0.0001), running injury (PR = 1.66; P < 0.0001), muscle injury (PR = 1.82; 0.0001), tendon injury (PR = 1.62: P < 0.0001), and runners in the experienced category (PR = 1.22; P < 0.0001). Conclusion: Novel risk factors associated with EAMC in distance runners were underlying chronic disease, medication use, a history of running injuries, and experienced runners. These factors must he identified as possible associations, and therefore be considered in the diagnosis and treatment of EAMC.