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Daniel Arvidsson, Mark Fitch, Mark L. Hudes and Sharon E. Fleming

Background:

Overweight children show different movement patterns during walking than normal-weight children, suggesting the accuracy of multisensory activity monitors may differ in these groups.

Methods:

Eleven normal and 15 high BMI African American children walked at 2, 4, 5, and 6 km/h on a treadmill wearing the Intelligent Device for Energy Expenditure and Activity (IDEEA) and SenseWear (SW). Accuracy was determined using indirect calorimetry and manually counted steps as references.

Results:

For IDEEA, no significant differences in accuracy were observed between BMI groups for energy expenditure (EE), but differences were significant by speed (+15% at 2 km/h to −10% at 6 km/h). For SW, EE accuracy was significantly different for high (+21%) versus normal BMI girls (−13%) at 2 km/h. For high BMI girls, EE was overestimated at low speed and underestimated at higher speeds. Underestimations in steps did not differ by BMI group at 4 to 6 km/h, but were significantly larger at 2 km/h than at the other speeds for all groups with IDEEA, and for normal BMI children with SW.

Conclusions:

Similar accuracies during walking may be expected in normal and overweight children using IDEEA and SW. Both monitors showed small errors for steps provided speed exceeded 2 km/h.

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David R. Dolbow, Richard S. Farley, Jwa K. Kim and Jennifer L. Caputo

The purpose of this study was to examine the cardiovascular responses to water treadmill walking at 2.0 mph (3.2 km/hr), 2.5 mph (4.0 km/hr), and 3.0 mph (4.8 km/hr) in older adults. Responses to water treadmill walking in 92 °F (33 °C) water were compared with responses to land treadmill walking at 70 °F (21 °C) ambient temperature. After an accommodation period, participants performed 5-min bouts of walking at each speed on 2 occasions. Oxygen consumption (VO2), heart rate (HR), systolic blood pressure (SBP), and rating of perceived exertion (RPE) were significantly higher during therapeutic water treadmill walking than during land treadmill walking. Furthermore, VO2, HR, and RPE measures significantly increased with each speed increase during both land and water treadmill walking. SBP significantly increased with each speed during water treadmill walking but not land treadmill walking. Thus, it is imperative to monitor HR and blood pressure for safety during this mode of activity for older adults.

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Jeff A. Nessler, Gerald Kephart, Jason Cowell and Charles J. De Leone

Studying spontaneous synchronization of stepping as two individuals walk on side-by-side treadmills may be useful for understanding the control of bipedal locomotion and may have implications for gait rehabilitation. Existing data suggest that this behavior is related to differences in leg length, walkway slope, and overground speed between partners, and might be promoted by altering these variables. This idea was evaluated here as 24 pairs of subjects stepped on side-by-side treadmills under several conditions of relative speed and slope. Overall, pairings that demonstrated very little spontaneous synchronization with the same treadmill speed and slope exhibited significant increases in this behavior when one treadmill was manipulated. Conversely, pairings that demonstrated a tendency to synchronize under normal conditions exhibited significant decreases in this behavior when either treadmill was altered.

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Chris Button, Stuart Moyle and Keith Davids

There has been no direct attempt to evaluate whether gait performed overground and on a treadmill is the same for lower limb amputees. A multiple case study approach was adopted to explore the degenerate movement behavior displayed by three male amputees. Participants walked overground at a self-selected preferred pace and when this speed was enforced on a treadmill (50 stride cycles per condition). The extremities of motion (i.e., maximum flexion) for the hip and knee joints differed between conditions (0.2–3.8°). For two participants, the temporal asymmetry of gait was reduced on the treadmill. Initial data suggest that research on amputees simulating overground walking on a treadmill might need to be interpreted with some caution.

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Scott C. White, Louise A. Gilchrist and Kathryn A. Christina

Prescribing an appropriate adaptation period is an important consideration when using treadmills for locomotion studies. The present study investigated within-trial accommodation to running on a force measuring treadmill. Force measures were derived from vertical reaction force records of 16 runners; 8 were experienced in running on a treadmill. Three dependent measures, the peak impact force (F1), the loading rate of the impact force (LR), and the peak active force (F2) were tested for significant differences (p < 0.05) every 2 minutes of a continuous 20-min run using a two-factor ANOVA (group × time) with one repeated measure (time). Coefficients of variation (CV) for each dependent measure were tested for statistical significance in the same way. There were no significant differences in F1, LR, or F2 over any samples for the 20-min running trials. There were no significant changes in CV values for the duration of the run. The results from the present study suggest that after 30 seconds of treadmill running, there were no significant within-day accommodation effects on vertical force measures over a 20-min treadmill run. Variability between individuals in the consistency of force measures, however, could be a confounding factor. This lack of consistent response for individuals should be considered when exposing participants to experimental designs involving treadmill locomotion.

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Rebecca E. Fellin, Kurt Manal and Irene S. Davis

Researchers conduct gait analyses utilizing both overground and treadmill modes of running. Previous studies comparing these modes analyzed discrete variables. Recently, techniques involving quantitative pattern analysis have assessed kinematic curve similarity in gait. Therefore, the purpose of this study was to compare hip, knee and rearfoot 3-D kinematics between overground and treadmill running using quantitative kinematic curve analysis. Twenty runners ran at 3.35 m/s ± 5% during treadmill and overground conditions while right lower extremity kinematics were recorded. Kinematics of the hip, knee and rearfoot at footstrike and peak were compared using intraclass correlation coefficients. Kinematic curves during stance phase were compared using the trend symmetry method within each subject. The overall average trend symmetry was high, 0.94 (1.0 is perfect symmetry) between running modes. The transverse plane and knee frontal plane exhibited lower similarity (0.86–0.90). Other than a 4.5 degree reduction in rearfoot dorsiflexion at footstrike during treadmill running, all differences were ≤1.5 degrees. 17/18 discrete variables exhibited modest correlations (>0.6) and 8/18 exhibited strong correlations (>0.8). In conclusion, overground and treadmill running kinematic curves were generally similar when averaged across subjects. Although some subjects exhibited differences in transverse plane curves, overall, treadmill running was representative of overground running for most subjects.

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Saryn R. Goldberg, Thomas M. Kepple and Steven J. Stanhope

We increased the accuracy of an instrumented treadmill’s measurement of center of pressure and force data by calibrating in situ and optimizing the transformation between the motion capture and treadmill force plate coordinate systems. We calibrated the device in situ by applying known vertical and shear loads at known locations across the tread surface and calculating a 6 × 6 calibration matrix for the 6 output forces and moments. To optimize the transformation, we first estimated the transformation based on a locating jig and then measured center-of-pressure error across the treadmill force plate using the CalTester tool. We input these data into an optimization scheme to find the transformation between the motion capture and treadmill force plate coordinate systems that minimized the error in the center-of-pressure measurements derived from force plate and motion capture sources. When the calibration and transformation optimizations were made, the average measured error in the center of pressure was reduced to approximately 1 mm when the treadmill was stationary and to less than 3 mm when moving. Using bilateral gait data, we show the importance of calibrating these devices in situ and performing transformation optimizations.

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Isabel S. Moore and Sharon J. Dixon

Interest in barefoot running and research on barefoot running are growing. However a methodological issue surrounding investigations is how familiar the participants are with running barefoot. The aim of the study was to assess the amount of time required for habitually shod runners to become familiar with barefoot treadmill running. Twelve female recreational runners, who were experienced treadmill users, ran barefoot on a treadmill for three bouts, each bout consisting of 10 minutes at a self-selected speed with 5 minute rest periods. Sagittal plane kinematics of the hip, knee, ankle, and foot during stance were recorded during the first and last minute of each 10-minute bout. Strong reliability (ICC > .8) was shown in most variables after 20 minutes of running. In addition, there was a general trend for the smallest standard error of mean to occur during the same period. Furthermore, there were no significant differences in any of the biomechanical variables after 20 minutes of running. Together, this suggests that familiarization was achieved between 11 and 20 minutes of running barefoot on a treadmill. Familiarization was characterized by less plantar flexion and greater knee flexion at touchdown. These results indicate that adequate familiarization should be given in future studies before gait assessment of barefoot treadmill running.

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Gregory B. Dwyer and Anthony D. Mahon

Little is known about the responses to graded exercise in athletes with cerebral palsy (CP). This study compared the ventilatory threshold (VT) and peak VO2 among athletes with CP during treadmill and cycle ergometry exercise. Six (4 men, 2 women) track athletes with CP volunteered to participate in the study. Graded exercise tests on a treadmill and cycle ergometer were performed on separate days to assess VT and peak VO2. Paired t tests were used to compare the two exercise modes. The VT, expressed as a percentage of peak VO2, was significantly higher on the cycle ergometer than on the treadmill. The absolute VO2 at the VT was similar during both testing modes, and peak VO2 was significantly higher on the treadmill than on the cycle ergometer. Similar to responses seen in able-bodied individuals, the VO2 at VT was similar during both modes of exercise, while the peak VO2 was 10% lower on the cycle than on the treadmill. Cycle ergometer peak VO2 in these athletes was higher than previous reports of individuals with CP for the cycle ergometer.

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Alon Eliakim, Mark Y. Moromisato, David Y. Moromisato and Dan M. Cooper

In this study, the hypothesis that improvements in functional and structural measures could be detected in the young, female rat with only 5 days of moderate treadmill training was tested. Eight-week-old female Sprague-Dawley rats were divided randomly into control (n = 10) and training groups (n = 11). Over the 5-day period, running duration and treadmill speed increased progressively. Maximal running time and gas exchange were measured on Day 6. In trained compared with control rats, maximal running time was 54% greater (p < .005), right hindlimb muscle was 16% heavier (p < .01), and end-exercise respiratory exchange ratio (RER) was 17% lower (p < .05). Substantial metabolic and structural adaptations occurred in young female rats after only 5 days of treadmill training. This protocol may be useful in discovering the initiating mechanisms of the training response in the young organism.