Baseline Injury Risk Factors for Runners Starting a Marathon Training Program *Joseph N. Chorley, MD, †John C. Cianca, MD, ‡Jon G. Divine, MD, and §Tamara D. Hew, DPM Departments of *Pediatrics and †Physical Medicine and Rehabilitation, Baylor College of Medicine, Houston; ‡Department of Family and Community Medicine, University of Texas Health Science Center–Houston, Houston; and §Private Practice in Podiatry, Houston, Texas, U.S.A. Objective: To describe the baseline characteristics of par- ticipants starting a 25-week marathon training program, and their relationship to injury risk factors. Design: Prospective survey. Setting: Community-based marathon training program. Participants: 1,548 of 2,314 registrants for the Houston Fit Marathon Training Program (mean age 35.8 ± 9.3 years, mean body mass index 24.3 ± 3.9, 63% female). Intervention: 4-page survey administered at registration. Main Outcome Measure: Running experience, training practices, demographics, chronic medical problems and previ- ous injuries. Results: Females were more likely to be classified as un- derweight and males as overweight or obese (p < 0.0001). The mean number of years of running experience was 6.2 ± 6.2. Most (87.5%) planned to train at a 9-minute mile or slower pace. 52.3% of the participants had not previously trained for a marathon. In the 3 months prior to starting the program 16.1% had been sedentary. Those runners who had not previously completed a marathon and not previously trained with Houston Fit had a higher prevalence of baseline training techniques that could be risk factors for injury. During the previous 3 years, 38.1% reported having an injury, and 35% of all injuries were still symptomatic at the start of the program. Conclusions: Training programs for the marathon attract more female athletes and those with less running and marathon experience. The prevalence of being overweight or obese is 35.6%. 16.1% are sedentary during the 3 months before starting this program. Training programs must take measures to estab- lish baseline fitness, to educate on injury prevention training techniques, and to set appropriate fitness goals. Clinical Relevance: The research study shows that many patients wanting to start a marathon training program are rela- tively untrained and inexperienced with reference to endurance running. These patients will need special care and education so as to minimize injury and maximize the effect on their physical activity habits. Key Words: Baseline fitness—Epidemiology—Injury— Marathon—Running. Clin J Sport Med 2002;12:18–23. INTRODUCTION In the United States, more than 40% of the population walk for exercise and 9% run or jog. 1 Runners, joggers, and walkers have seen the marathon as one of the ulti- mate tests of fitness and are attempting this challenge in record numbers. In the United States in 1998, there were an estimated 419,000 marathon finishers, which is an increase of 60% from 1990 and 1,600% from 1976. The number of finishers has been projected to continue to increase at a rate of 4% per year (unpublished data from USA Track and Field). The United States has placed a priority on increasing regular physical activity so as to improve our nation’s health and decrease the mortality from associated chronic medical diseases. The training required to run a marathon has the potential to impact the immediate and long-term prevalence of both physical inactivity and regular, vigorous physical activity. Nation- ally, physical inactivity (no leisure-time physical activity in the previous 2–4 weeks) prevalence estimates range from 21.7 to 28.7% of the population. 1 Females and older adults are more inactive than their male, younger counterparts, however, they also represent the groups with the largest growth in the number of marathon fin- ishers. Although running and physical activity have been well studied, the training required to complete a marathon has not been well investigated. Most epidemiological re- search on running is based on retrospective information collected from entrants to a single event. This method excludes those individuals who start training but are not able to compete in the event. To understand the public health impact of marathon training on physical activity patterns, we must understand not only the characteristics of those who complete the marathon, but all those who start to train for the event and then drop out. The drop- out rate in marathon training for those who enter the race has been reported to be 30–50%, with the most common Received March 2001; accepted October 25, 2001. Address correspondence to Joseph N. Chorley, MD, Department of Pediatrics, Section of Adolescent Medicine and Sports Medicine, Bay- lor College of Medicine, 6621 Fannin St., MC3-3340, Houston, TX 77030, U.S.A. E-mail jchorley@bcm.tmc.edu Clinical Journal of Sport Medicine, 12:18–23 © 2002 Lippincott Williams & Wilkins, Inc., Philadelphia 18