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The Underwater Treadmill Project

The Huffines Institute for Sports Medicine and Human Performance along with the Department of Health and Kinesiology at Texas A&M, received grant monies from Hydroworx Inc. to begin research and testing on a new underwater treadmill rehabilitation system.

The giant pool / treadmill system is designed to enhance the healing process of numerous types of athletic injuries and reduce the time an injured athlete is out of competition. The Huffines and A&M research team are attempting to determine if it is also effective in areas of weight loss, changes in blood lipids related to heart disease risk, changes in factors influencing protein transcription, as well as comparing the system's rate of inducing caloric expenditure to that of land-based treadmills. Research Began in 2006 and is ongoing. Several research presentations at Regional, National, and International conferences have been delivered and manuscript preparation is underway. The abstracts of three research presentations delivered at the International American College of Sports Medicine meeting are given below:

Prediction of Oxygen Costs of Exercise on a Water Treadmill. N.P. Greene, E.S. Greene, G.S. Miller, A. Muller, B.E. Hansen, J.W. Womack, J.S. Green, A.F. Carbuhn, T.H. Meade, S.F. Crouse. Department of Health and Kinesiology, Texas A&M University, College Station, TX (sponsor S.F. Crouse, FACSM) No known research has been completed investigating the metabolic responses to exercise on an underwater treadmill. PURPOSE: To derive a means of predicting rate of oxygen consumption (VO2) during exercise on an underwater treadmill. METHODS: Twenty-one men and 20 women participated in this investigation. The subjects’ mean age, height (Ht), weight (Wt), were 41.6 yr, 173.8 cm, and 90.9 kg, respectively. Exercise was performed on a treadmill immersed in a pool with resistance jets in front of the subject. Subjects performed one practice session and five experimental sessions. Exercise sessions progressed from 2 to 7 mph, increasing 1 mph every 3 min, with jet pressures of 0, 25, 50, 75, and 100% of maximal resistance held constant and randomly assigned to each session. Jets were pointed at the subject’s umbilicus and water depth was set to the 4th intercostal space. Metabolic responses were recorded using indirect open circuit calorimetry, and measurements were taken the final 15 s of each stage. Exercise sessions continued until one of 3 termination criteria were met: heart rate above 85%max, subject request, or completion of the protocol. Regression equations were developed by multiple regression analysis using the variables of height, weight, speed, and jet percentage to predict VO2. RESULTS: All coefficients were significant (P<0.001) for predicting both absolute and relative VO2. Collinearity diagnostics revealed no variable correlation problems. The equation for absolute VO2 was VO2 (LO2/min) = (0.028) * Ht in centimeters + (0.002) * Wt in kilograms + (0.308) * Speed in mph + (0.011) * Percent max jet – 5.333. The equation for relative VO2 was VO2 (mlO2/kg/min) = (0.297) * Ht in centimeters – (0.159) * Wt in kilograms + (3.594) * Speed in mph + (0.131) * Percent max jet – 38.222. R-squared values were 0.735 and 0.743 for prediction of absolute and relative VO2, respectively. CONCLUSIONS: These data provide a reasonably reliable means of predicting oxygen consumption for exercise on a water treadmill. This is of great importance in providing accurate exercise prescriptions for this mode of exercise.

Changes in Blood Lipids after 12-Weeks of Aerobic Training on either a Water or Land Treadmill A.F. Carbuhn, N.P. Greene, E.S. Greene, G.S. Miller, A. Muller, B.E. Hansen, J.W. Womack, J.S. Green, T.H. Meade, S.F. Crouse. Department of Health and Kinesiology, Texas A&M University, College Station, TX (sponsor S.F. Crouse, FACSM) To the authors’ knowledge, there are no published investigations regarding the lipid changes in response to aerobic exercise on an underwater treadmill. PURPOSE: To compare pre- and post-training lipid changes on a land treadmill and underwater treadmill with equivalent workloads. METHODS: There were 27 subjects: 13 (6 female, 7 male) in the underwater treadmill group (UW) (mean age=43 years, mean weight=87.3 kg) and 14 (9 female, 5 male) in the land-based treadmill group (LT) (mean age=44 years, mean weight=86 kg). Prior to exercise training regimens, blood samples were taken from both groups and analyzed for triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C). Both sets of subjects began a 12 week exercise regimen with weekly intensity progressions. Exercise intensities for both treadmill groups were calculated at each progression so subjects in both groups expended the same amount of calories during each exercise bout. The regimen began with subjects expending 250 kcals per bout, progressed to 500 kcals per bout by the end of week 6, and remained at that level for the duration of the study. Blood samples were taken again at post training assessment after completion of the exercise regimen . Components of the lipid profile between groups was analyzed using a Student’s t-test with unequal variance and within groups was analyzed using a paired Student’s t-test, with the comparison-wise error rate set at a =0.05. RESULTS: See Table 1. Table 1. Pre vs. Post TG, TC, HDL-C, and LDL-C (mg/dL) means ± SD on LT and UW

Comparison of oxygen consumption and heart rate response to exercise on land versus water treadmill. E.S. Greene, N.P. Greene, B.E. Hansen, G. Miller, A. Muller, J.W. Womack, J.S. Green, A.F. Carbuhn, T. Meade, S.F. Crouse. Department of Health and Kinesiology, Texas A&M University, College Station, TX (sponsor S.F. Crouse, FACSM) Little research has been performed measuring physiological responses to exercise on an underwater treadmill. PURPOSE: To compare the oxygen consumption (VO 2) and heart rate (HR) response to exercise on a land and an underwater treadmill. METHODS: Twenty-four men and 25 women participated in this investigation. The subjects’ mean age, height, and weight were 40.5yr, 173.9cm, and 88.3kg, respectively. The subjects performed one exercise session on the land treadmill (LTM) at zero grade and one on the underwater treadmill (WTM). Water depth was standardized to the height of the fourth intercostal space of each subject. Subjects performed one practice session on the WTM to become familiar with this novel mode of exercise. The exercise sessions were designed as a graded protocol such that each session began with the treadmill at 2mph, with speed increasing 1mph every 3 minutes, up to 7mph. At the end of each stage, exercise HR was recorded. Metabolic responses were recorded using indirect open-circuit calorimetry. Measurements were taken from the final 15 seconds of each stage. Exercise sessions continued until one of three termination criteria were met: HR exceeded 85% max, subject request, or completion of the protocol. Oxygen consumption and HR response to LTM and WTM were compared using a paired Student’s t-test, with the comparison-wise error rate set at a =0.05. RESULTS: See Table 1. Table 1. VO 2 (LO 2*min -1) and HR (bpm) responses to exercise on LTM vs WTM at varying speeds