Comparison of Land vs. Water Walking on Acute Metabolic, Cardiovascular, Affective Domain & Physical Activity Patterns in Overweight vs. Normal Weight Adults Dennis Dolny, Ph.D. - Utah State University

Purpose and Methods:
The purposes of this study were to: 1) compare the metabolic and cardiovascular effect of water depth versus land on energy expenditure during walking at selected speeds in persons of variable weight; 2) record perceptions of effort and discomfort plus affect of participants during and immediately following each exercise session; 3) determine if the type of walking exercise impacts the amount of estimated weekly physical activity in these subjects. Eighteen female subjects ranging in age from 21-60 yrs and body mass index (body wt. in kg/ht. in meters2) of 21.5 – 44.94 walked on three separate days in one week on a land treadmill (TM) in 24° C air and on a separate week in a water treadmill (ATM, Hydroworxtm) at 30°
C. Each session consisted of six 5-minute walking bouts of 1.5, 2.0, 2.5, 3.0, 3.5 and 4.0 miles per hour. For ATM the water depth was different each day, using a water depth either at the xiphoid level (xip), 10 cm below xiphoid (-10cm), and 10 cm above xiphoid (+10cm). During each walking bout heart rate (HR), oxygen consumption (VO2), Ventilation (VEBTPS), Tidal Volume, (VT) were recorded continuously. Ratings of Perceived Exertion (RPE, overall and leg exertion), leg pain/discomfort (LP), and measures of affect (Feeling Scale (FS) and Felt Arousal Scale (FAS)) were solicited at the end of each bout. Prior to and following the fi rst and third session of both land and water sessions, subjects completed an exercise feeling inventory (EFI), a subjective exercise efficacy scale (SEES), a negative affect scale (NAS), a future exercise intention scale (EIS), and a physical activity enjoyment scale (PAES).

Results:
Regardless of walking speed, VO2 (and estimated energy expenditure) and exercise heart rate were influenced by water depth, with -10cm significantly greater than xip, +10cm and Land, and xip significantly greater than +10cm and Land. Land VO2 and heart rate were similar to +10cm. When the relationship between VO2 and BMI was examined, a significant relationship existed during Land (r=0.78, p=0.0001) and -10cm (r=0.59, p<0.05) ATM sessions, but not for xip (r=0.35, p>0.05) and +10cm (r=0.34, p>0.05) ATM sessions. Similar relationships were present when VO2 was compared with body weight.
When subjects were separated into two groups, those with BMI scores of <30 and >30, the groups reported similar negative affect following Land sessions but a significantly lower negative affect following the ATM week. For EFI, >30 BMI group experienced significant increases following ATM sessions for Revitalization Tranquility and Positive Energy with and small decrease in Exhaustion. Land improved Tranquility and Positive Energy, and increased Exhaustion during the initial session only. For <30 BMI group, Tranquility increased for both Land and ATM sessions, Revitalization increased more for ATM vs Land. Positive Energy increased for the initial sessions of land and ATM, while Exhaustion decreased in all but initial ATM session. FS tended to be more positive in ATM vs Land sessions while FAS had little change with few exceptions.
All subjects reported that the ATM experience was significantly more enjoyable than Land sessions. But they also suggested they would likely participate in future (EIS) Land or ATM sessions to a similar extent.

Conclusions:
These results suggest that fairly small changes in water depth influences water walking HR and oxygen consumption Regardless of BMI. Subject perception of exercise effort and leg pain were greater in Land sessions suggesting the hydrodynamic effect of water enhances the exercise experience. With proper water depth estimated energy expenditure is not compromised. In fact larger sized individuals may experience greater energy expenditures with less leg pain and perceived effort.

Biographical Information:

Dennis Dolny received his BA and MS in Physical Education from Wake Forest University and PhD from Kent State University in Physical Education with an emphasis in Exercise Physiology. For the past 24 years he was on faculty at the University of Idaho where he also directed the Human Performance Laboratory. In 2008 he accepted the Department Head position in Health, Physical Education & Recreation in the College of Education & Human Services at Utah State University. He has chaired ten doctoral committees and published 30 peer-reviewed research articles. His recent research projects have included studying the acute effects of vibration exposure on subsequent muscle power output, developing techniques to monitor skeletal muscle activity during walking and running in water, and currently funded projects involve the use of aquatic exercise exposure on energy expenditure, joint discomfort and perceived effort in overweight subjects and those with osteoarthritis. At USU his laboratory collaborates with USU Sports Medicine examining the role of hydrotherapy in rehabilitation following lower extremity surgical procedures and joint replacement in the elderly.