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065 Experienced runners with an above average training load have the highest risk of exercise associated muscle cramping (EAMC)
  1. Martin Schwellnus1,3,5,
  2. Esme Jordaan2,4
  1. 1Sport, Exercise Medicine and Lifestyle Institute (SEMLI), Pretoria, South Africa
  2. 2Biostatistics Unit, South African Medical Research Council, Cape Town, South Africa
  3. 3IOC Research Centre, South Africa, Pretoria, South Africa
  4. 4Statistics and Population Studies Department, University of the Western Cape, Cape Town, South Africa
  5. 5Emeritus Professor of Sport and Exercise Medicine, Faculty of Health Sciences, University of Cape Town, South Africa, Cape Town, South Africa


Background Running experience and training may be risk factors for exercise associated muscle cramping (EAMC). However, multiple experience and training variables are inter-dependent. A latent class variable may be used to test associations between multiple experience and training variables and EAMC.

Objective Is there an association between EAMC and a latent class training variable, based on multiple inter-dependent experience and training variables?

Design Cross-sectional study.

Setting Two Oceans Marathons 2012–2015.

Patients (or Participants) 76211 consenting race entrants.

Interventions (or Assessment of Risk Factors) Runners completing a pre-race screening questionnaire reported a history of EAMC and multiple experience and training variables: years of recreational running, years of racing, weekly training frequency, 12 months training distance, average training speed. Multiple experience and training variables were used to inform a latent class variable dividing runners into mutually exclusive classes so as to best explain the meaning of the chosen classes. Five experience/training classes (ET classes) were identified: ET class 1 (less experienced runners, lowest training) (64%), ET class 2 (average experience, average training) (18%), ET class 3 (fairly experienced, above average training) (8.6%), ET class 4 (2ndleast experience, training far above average) (6.4%), ET class 5 (very experienced, above average training) (3%).

Main Outcome Measurements Prevalence of EAMC (%) by ET classes (1–5).

Results There were significant differences in EAMC prevalence among ET classes (p<0.0001). EAMC prevalence was highest in ET class 5 (27%) (very experienced, above average training) vs. ET class 1 (11%) (less experienced runners, lowest training).

Conclusions Runners with more experience and an above average training profile had the highest prevalence of EAMC. Using ET classes to categorise runners by experience and training, instead of multiple individual inter-dependent training variables, may be more informative to explore relationships between running experience, training variables and medical conditions such as EAMC.

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