Award Date


Degree Type


Degree Name

Master of Science (MS)


Kinesiology and Nutrition Sciences

First Committee Member

Laura Kruskall

Second Committee Member

John Young

Third Committee Member

Richard Tandy

Fourth Committee Member

Sue Schuerman

Number of Pages



Purpose: The purposes of this study were first to assess the vitamin D status and bone mineral density (BMD) in male and triathletes (N=15), female triathletes (N=13), and non-athletes (N=14), and to determine if circulating vitamin D was correlated with body composition, BMD, dietary calcium and vitamin D intake in triathletes. The second purpose was to determine if triathletes have a different level of serum vitamin D, body composition, BMD, dietary calcium and vitamin D intake then non-athletes. The third purpose was to determine if BMD was correlated with body composition (body mass, percent body fat, BMI) in triathletes.

Methods: 25(OH)D vitamin concentrations were measured in 38 triathletes (15 male/13 female) and 14 non-athletes (male/female). Dietary intake of vitamin D and calcium was assessed via questionnaire, and Dual Energy X-ray Absorptiometry (DEXA) measured body composition and bone mineral density of the dual femur, and lumbar spine. Blood samples were collected via finger lancet extracting 600 μL of blood and 25(OH)D was determined using a commercially available ELISA kit. Using SPSS, the data were analyzed using Pearson's r and one-way ANOVA.

Results: Sufficient 25(OH)D concentrations were found in both the triathletes and non-athletes and averaged 62.8 + 23.9, 67.5 + 14.3, 64.7 + 25.3 ng/mL (mean + SD) in female triathletes, male triathletes, and non-athletes respectively. Vitamin D status was not correlated (p > 0.05) with total body bone density (r = - 0.019) or bone density in the lumbar spine (r = 0.101), dual femur (r = -0.042), or ward's triangle (r = 0.097). An inverse relationship between 25(OH)D concentration and body fat was found to be significant in the male triathlete group (r = -0.730, p = 0.002) and in the control group (r = -0.573, P = 0.032). Body mass was significantly correlated with bone density in the lumbar spine (r = 0.338, p = 0.027) and wards triangle (r = 0.366, p = 0.016). When correlations were adjusted between subject groups, the relation between body mass and bone mineral density (r = 0.685, p = 0.007), duel femur (r = 0.653, p = 0.011), lumbar spine (r = 0.718, p = 0.004), and wards triangle (r = 0.617, p = 0.029) were significant in the control group.

Conclusion: The current study demonstrates that healthy triathletes and non-athletes can achieve adequate to optimal 25(OH)D concentration through routine sun exposure and dietary sources. Maintaining a healthy weight, particularly with a lower body fat percentage could also increase ones vitamin D status.


Body composition; Bone mineral density; Bones; Calcium in the body; Exercise; Nutrition; Triathletes; Vitamin D; Vitamin D in the body


Human and Clinical Nutrition | Nutrition | Sports Studies

File Format


Degree Grantor

University of Nevada, Las Vegas




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