Scheduled for Research Consortium Poster Social: Representative Research in HPERD, Wednesday, March 14, 2007, 4:30 PM - 6:00 PM, Convention Center: Exhibit Hall Poster Area I

Pedal Reaction Forces During Exercise on the Elliptical Trainer

Kathleen M. Knutzen, Andrew Lawson, Lorraine Brilla and Gordon Chalmers, Western Washington University, Bellingham, WA

The elliptical trainer was developed as a cardiovascular machine that could provide an exercise similar to running but with reduced impact forces. There is little or no information in the literature on the actual forces generated at the pedal during exercise on an elliptical trainer. Purpose: The purpose of the present study was to measure pedal reaction forces on the elliptical trainer under three workload conditions. Methods: Twenty six college aged, apparently healthy subjects (age=22.19+.85 years; weight=74.04+ 19.33 kg; height=169.85+9.75 cm) with no previous knee injury and with previous experience on an elliptical trainer volunteered for this study. Kinetic data including vertical and anteroposterior forces were collected using a custom built orthogonal force transducer located under the right foot pedal on the elliptical trainer. After a practice and warm-up session on the elliptical, each subject strode for two minutes at three incline levels: 13-degrees, 25-degrees, and 40-degrees. During this time, transducer data were collected for 10 seconds (600 Hz) while subjects matched a cadence of 120 steps per minute. Results: The peak anterior shear force at 13-, 25-, and 40-degrees were 148.08+12.72 N (.206 body weight (BW)), 155.25+13.91 N (.215 BW), and 180.69+16.26 N (.259 BW), respectively, and even though there was a tendency toward an increase in the higher ramp positions, these differences were not significant. Likewise, the mean peak posterior shear force did not significantly change at 13-, 25-, and 40-degrees with average values of 107.91+62.73 N (.152 BW), 111.28+61.17 N (.159 BW), and 114.65+ 89.21 N (.153 BW), respectively. There was a significant increase (p=.001 (N); p=.003 (N/BW) in the mean peak vertical forces across the ramp settings of 13-, 25-, and 40-degrees at .49 N+45.92 (1.10 BW), 834.38+49.11 N (1.15 BW), and 865.73+56.02 N (1.19 BW), respectively. The significant vertical force findings had meaningful effect sizes, eta2 = .29 (N) and .34 (N/BW). Conclusion: Forces generated at the foot during performance of exercise on an elliptical trainer in three ramp positions was in the range of 1BW in the vertical direction and about 15-20% of body weight in the anteroposterior direction. These values are similar to those seen in walking and do not approach force levels considered to have higher potential for injury.

Instrumented pedal provided by Precor, Inc.

Keyword(s): exercise/fitness/physical activity, facilities/equipment

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