Author and graduation date: Julie Ann BURKS, May, 1997

Committee members: Anthony A. Sucec (Chair), Michael J. Buono, David Lesley

Thesis title: Gender Differences in Lactate Threshold: Lab and Field

The purpose of this study was first to determine the reliability and validity of a proposed 800 meter field lactate threshold (800LT) test for a representative sample of female and male distance runners with a wide range of performance levels against a standard lab lactate threshold (LLT) test. It also was intended to identify any differences in lactate threshold (LT) between males and females. Twenty females and 20 males between 17 and 46 years (mean age = 33 + 6.6 yrs) signed an informed consent and participated in this investigation. Tests in the lab included, but were not limited to, hydrostatic weighing, maximal oxygen uptake (VO2max) and laboratory testing. Field-testing consisted of two repeat 800m LT tests and two repeat 3,000m runs completed within 1 to 2 weeks of each other for reliability. No significant test-retest differences were found for either field test. The 800m LT test and the 3,000m run were found to be reliable with intraclass correlation coefficients of : R = 0.96 (95% CI = 0.95-1.17), Sy.x. = 7.11 m/min and R = 0.99 (95% CI = 0.87-0.99), Sy.x. = 1.67 min, respectively. Validity was determined using the LLT as a lab criterion and the 3,000m run as a field criterion. An interclass validity coefficient for the 800m LT of r = 0.98 (95% CI= 0.72-1.02), Sy.x. 10.57m/min was determined. Regarding gender differences, statistically significant differences (p <0.05) between females and males were found in mean VO2max, (57.37 + 8.00 ml/kg/min for females and 63.11 + 6.69 ml/kg/min for males), in the average number of days per week training (5.44 + 0.88 d/wk for females and 4.58 + 1.19 d/wk for males ) and consequently, in the miles per week training (44.62 + 21.18 mi/wk for females and 29.81 + 11.92 mi/wk for males). The higher mean raining volume for women in this study in not similar to other studies on distance runners. Typically, men train at higher volumes as well as speeds than women. Consequently, the finding of no differences between females and males in velocity at LT (m/min) or VO2 at LT (ml/kg/min) which were expected, were not seen in this study (velocity at LT: 237.8 + 21.17 m/min and 250.3 + 21.42 m/min for females and males, respectively and VO2 at LT: 47.19 + 6.81 ml/kg/min and 50.61 + 6.27 ml/kg/min for females and males, respectively). It may be that the female subjects do not constitute a representative sample. It was concluded that the proposed 800m LT test was reliable and valid for a heterogeneous sample of distance runners.

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