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Sarah J. Hanson, Penny McCullagh and Phyllis Tonymon

In 1988, Andersen and Williams proposed a model to explain the stress-injury relationship. The present study tested portions of this framework by investigating frequency and severity of injury occurrence in track and field athletes from four NCAA Division I and II universities. Personality characteristics (locus of control and sport competition trait anxiety), history of stressors (life stress, daily hassles, and past injury), and moderating variables (coping resources and social support) were assessed before the season began. Discriminant analyses indicated that four variables (coping resources, negative life stress, social support, and competitive anxiety) differentiated the severity groups. For injury frequency, coping resources and positive life stress differentiated the groups.

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Nicholas J. Hanson, Sarah C. Martinez, Erik N. Byl, Rachel M. Maceri and Michael G. Miller

Purpose: Although the effect of caffeine in thermoneutral or cool environmental conditions has generally shown performance benefits, its efficacy in hot, humid conditions is not as well known. The purpose of this study was to further examine the effect of caffeine ingestion on endurance running performance in the heat. Methods: Ten trained endurance runners (6 males; mean [SD] age = 26 [9] y, height = 176.7 [5.1] cm, and mass = 72.1 [8.7] kg) came to the lab for 4 visits. The first was a VO2max test to determine cardiorespiratory fitness; the final 3 visits were 10-km runs in an environmental chamber at 30.6°C and 50% relative humidity under different conditions: 3 mg·kg−1 body mass (low caffeine dosage), 6 mg·kg−1 (moderate caffeine dosage), and a placebo. Repeated-measures analyses of variance were used to determine the effect of condition on the 10-km time, heart rate, core temperature, rating of perceived exertion, and thermal sensation. Results: There was no difference in the 10-km time between the placebo (53.2 [8.0] min), 3-mg·kg−1 (53.4 [8.4]), and 6-mg·kg−1 (52.7 [8.2]) conditions (P = .575, ηp2=.060). There was not a main effect of average heart rate (P = .406, ηp2=.107), rating of perceived exertion (P = .151, ηp2=.189), or thermal sensation (P = .286, ηp2=.130). There was a significant interaction for core temperature (P = .025, ηp2=.170); the moderate-dosage caffeine condition showed a higher rate of rise in core temperature (0.26 [0.08] °C·km−1 vs 0.20 [0.06] and 0.19 [0.10] °C·km−1 in the low-caffeine and placebo conditions, respectively). Conclusion: The results support previous research showing a thermogenic effect of caffeine, as the moderate-dosage condition led to a greater rate of heat storage and no performance benefits.