November 2009

Document Type


Degree Name



Oregon Health & Science University


Sport related injuries affect approximately one third of US adolescent athletes, resulting in 2 million injuries annually. Most injury prevention research has focused on pre-season screening, rule modification, and protective equipment. However, high injury rates persist, suggesting the need for an expanded injury model that takes into consideration lifestyle factors and behaviors, which includes diet. This may be a productive line of research as adolescents’ diets often are inadequate. Consequences of inadequate protein intake include increased lean tissue catabolism and weakened recovery response from exercise, potentially leading to increased injury risk. This purported relationship led us to test the hypothesis that protein intake is inversely related to frequency of sport related injuries among high school athletes. A convenience sample of 270 adolescent athletes from 6 high schools completed anonymous surveys near the conclusion of the spring sport season (2009). Sports represented included women’s lacrosse, volleyball, softball, tennis, and track and field and men’s baseball, tennis, and track and field. The survey included the Block Kids Screener™ for their dietary assessment, and additional items for demographic, anthropometric, and sport related injury information. Data for males (n=127) and females (n=101) was analyzed separately. Descriptive statistics were used to characterize the sample, and two sample proportion z-tests were used to determine differences in injury rate among athletes consuming low, medium and high amounts of protein. Independent t-tests were used to analyze differences in the mean dietary protein intake between those who reported and did not report injuries. Participants had a mean (± SD) age of 16 ± 1 year. The mean BMI for males was the 68th ± 25th percentile and for females 60th ± 22nd percentile. Eighty-four percent of participants were white. The average energy and protein intake was 2070 ± 808 kcal/d and 97 ± 41 g/d for males and 1371 ± 534 kcal/d and 57 ± 25 g/d for females. The ratio of daily protein intake to body weight was 1.3 ± 0.6 g/kg/d for males and 1.0 ± 0.5 g/kg/d for females, compared to the 1.2-2.0 g/kg/d recommended for athletes. Self-reported energy and macronutrient intakes were lower than expected for adolescents. Thirty-four percent of males and 31% of females were injured at least once during the sport season. Leg injuries were most common for both. Protein intake was not different among males consuming low, medium, or high amounts of protein when protein intake was indexed as g/d, g/kg/d, or g/1000 kcals. However, interestingly when protein intake was indexed to body weight, females in the low protein group had a significantly higher rate of injuries than the high protein group (p = 0.0002). Although total injuries were not related to protein intake among males, mean dietary protein intake for adolescent males reporting shin splints was significantly less than those without shin splint injuries (p = 0.015). Findings are limited by the single sport season, relatively small participant numbers and instrument validity. Despite these limitations, results suggest a potential relationship between low protein intake and injuries. This is the initialobservation of this potentially important finding. Before secure recommendations can be made concerning adolescent athletes’ protein intake future studies are needed with additional participants, better characterization of injury and validated tools to measure energy and macronutrient intake.




Graduate Programs in Human Nutrition


School of Medicine



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