Date of Award

2011

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Kinesiology and Physical Education

Advisor

Robert A. Lehnhard

Second Committee Member

Stephen A. Butterfield

Third Committee Member

Shihfen Tu

Abstract

The purpose of this study was to determine the metabolic effect(s) of four graded exercise tests (GXT) on the underwater treadmill (UWT), and compare them to the results from performing the standard Bruce protocol17 on a traditional land treadmill (LT). Methods: Twelve male Division I college athletes performed the stand Bruce protocol on a LT and 4 different GXT protocols on the UWT. Each test was performed to volitional max. Oxygen consumption (VO2), heart rate (HR), respiratory exchange ratio (RER) and blood lactate (BL) were measured at regular intervals throughout each of the GXTs. A two-way ANOVA with repeated measures was used to determine any main effect among the variables within the protocols and within the stages. Established effects were identified further using Tukey's post-hoc analysis. Results: VO2 and HR were positively correlated in all the GXTs, (r= .992-.999). When comparing the UWT GXTs to the Bruce, significant (p < 0.001) differences were found within certain stages for each of the dependent variables. While the Bruce resulted in attainment of VO2maX, (mean = 55.72 + 5.92 ml/kg/min), only one of the UWT GXTs resulted in the same level of metabolic stress. At maximum speed and water velocity, the UWT produced a mean VO2 of 53.9 + 3.68 ml/kg/min. HR and RER both increased by stage in all the GXTs as did BL. OBLA was identified in all of the GXTs with the exception of one of the UWTs. Mean BL at OBLA ranged from, 3.12 + 1.31 to 5.98 + 4.24 mmol/dl. Conclusion: Results suggest that an UWT GXT protocol can be developed that would produce metabolic results similar to the Bruce through stage 5. Buoyancy and variation in biomechanics need to be studied further for their effects on energy metabolism while performing work on the UWT. However, this study provides a better understanding of the metabolic demands at different treadmill speeds and water jet settings with the UWT.

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