Author and graduation date: Jonna STENQVIST, December, 2000

Committee members: Anthony Sucec (Chair), Michael Buono, Anthony Cherin

Thesis title: The Effect of Acute Low Hypoxia on the Validity of the Ventilatory Threshold

The purpose of this study was to determine if the ventilatory threshold (VT) is a valid measure of the lactate threshold (LT) at low hypoxia (1,410 m) for trained distance runners. It was hypothesized that there would be no difference between LT velocity (LTvel) and VT velocity (VTvel) at sea level (SL), no difference between LTvel and VTvel at low altitude (ALT), and that a slower threshold velocity (Tvel) would be found at ALT than at SL. Six female and six male distance runners (19 to 39 years old) performed two 800mLT field tests, one at SL and one at ALT. The testing protocol was a randomized, counterbalanced design. The 800mLT test used consisted of four to nine evenly paced 800m runs with approximately 3.5 to 4 min of rest. The initial speed was 180 to 250 m/min depending on fitness level (determined by V02max) and training speed, and was increased by 10 m/min until LT, determined by at least two consecutive increases in lactate concentration. Subjects were tested in groups, where one group was running and the other was resting, walking or jogging. The LT and VT tests were performed simultaneously. Results of a 2 x 2 repeated measurement ANOVA indicated a significant altitude effect (p < 0.05). Both LT and VT occurred at significantly slower velocities at ALT (235.4 + 9.0 and 230.5 + 9.7 m/min) than at SL (249.6 + 9.5 and 245.3 + 10.3 m/min)(p < 0.05). All threshold measures were highly correlated (r > 0.96). We conclude that VT is a valid measure for LT at low altitude, and that Tvel is slower at low altitude than at SL.

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