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Abstract

The study compared the acute and training responses of deep water running (DWR) to treadmill running (TMR) in elderly women. Twenty inactive, healthy women (64.5 ± 3.5 years) volunteered to participate in this study. Subjects were randomly and evenly divided into a control or exercise group. Maximal TMR exercise response was achieved using a graded protocol of 3.5mph, increasing 2% grade/min. Maximal DWR exercise response was achieved using a tethered apparatus starting at an initial load of 300g and increasing lOOg/min. Training intensities were set at 70%, 75%, and 80% of pre-training DWR maximal heart rates (HR) during weeks 1-2, 3-5, and 6-8, respectively. Maximal oxygen consumption (VC>2max), ventilation (VE), heart rate (HR), and respiratory exchange ratio (RER) were measured during DWR and TMR maximal tests, both pre and post training. Blood samples were taken 2 minutes post exercise to determine blood lactate concentrations (Blac). Within subject repeated measures ANOVA was performed to determine whether statistical differences occurred across exercise conditions (TMR vs. DWR), over time (training effect), and with training responses between TMR and DWR (specificity of training). Data obtained pertaining to the acute responses of DWR and TMR revealed significantly higher TMR V02max (23.94 vs. 18.49 and 21.59 vs. 17.65 ml/kg/min, p<0.05) and HR (164.50 vs. 157.70 and 161.75 vs. 156.13 beats/min, p<0.05) compared to DWR for exercise and control groups, respectively. Training for 8 weeks with DWR increased TMR VE (14%, p<0.05), TMR V02max (18%, p<0.05), and DWR VE (15%, p<0.05). Deep water running V02max did not statistically improve within the exercise group over 8 weeks (p>0.05). However, significant differences did exist between exercise and control groups over time (group by time interaction, p<0.05), indicating a training effect. The inability to reach statistical significance in DWR VC^max within the exercise group over time may be attributable to the characteristics of water immersion causing ventilation/ perfusion inequalities and/or the protocol used to assess DWR maximal exercise capacity, in which case muscular strength could have been a limiting factor. While the data obtained in this study did not show within group improvements in DWR VChmax, differences across groups over time combined with improvements in TMR VO"2max, TMR VE, and DWR V E indicate that training adaptations do occur with DWR training protocols, despite the lower physiological stress induced with WI.