Level Treadmill Walking Research Articles

Validity and Reliability of the FitSense FS-1 Speedometer During Walking and Running

This study examined the criterion-related validity and the reliability of the FitSense FS-1 Speedometer for estimating distance, speed, and energy expenditure (EE) during walking and running. The study was divided into two parts. Part I investigated the validity and the reliability of the FitSense for estimating distance while walking and running around a 400-m track (n = 24). Part II looked at the validity of the FitSense for estimating speed and EE during level treadmill walking (4.8, 6.4, and 8.0 km . h -1 ) and running (8.0, 9.6, and 11.2 km . h -1 ). Twelve of the original 24 subjects completed Part II. The results of Part I indicated that the FitSense accurately estimated walking distance, but it underestimated running distance by an average of 3.5% (p=0.016). Testretest reliability was deemed adequate for both walking and running distance (ICC = 0.87 and 0.84, respectively). In Part II, the FitSense overestimated speed during treadmill walking at 8.0km.h -1 (p<0.001) and underestimated EE at two walking speeds (6.4 and 8.0 km.h -1 ) (p < 0.01). No significant differences were found for speed or EE predictions while running at any speed. In summary, the FitSense FS-1 Speedometer provided valid estimates of walking distance during track tests, and valid estimates of speed during treadmill walking (4.8 and 6.4 km.h -1 ) and running (9.6 and 11.2 km.h -1 ). However, the FitSense underestimated running distance during track tests. In addition, the FitSense overestimated speed and underestimated EE in the transition between walking and running (8.0 km.h -1 ).

Within- and between-day stability of treadmill walking VO2 in children with hemiplegic cerebral palsy

Within- and between-day stability in locomotor energy use was quantified in 13 children with hemiplegic cerebral palsy (CP). During testing, subjects were familiarized with the laboratory environment (Session 1), performed three 5 min level treadmill walks (Trials 1-3) at 0.67 m*s(-1) (Session 2), and completed a single 5 min walk (Trial 4) at 0.67 m*s(-1) (Session 3). In Sessions 2 and 3, heart rate (HR) was assessed and expired air was collected and analyzed to determine VO2. Data analyses revealed no significant difference (P > 0.05) in either net VO2 (ml kg(-1)*min(-1)) or EEI(HR) (b*m(-1)) across the three trials performed in Session 2 and between average measures of net VO2 and EEI(HR) quantified in Session 2 and those obtained in Session 3. Mean within-day coefficient of variation (CV) values for net VO2 and EEI(HR) were 8.6% +/- 8.5% and 13.9% +/- 7.8%, respectively. Analysis of between-day variability and energy expenditure revealed a between-day CV value of 13.1% for net VO2 and 24.0% for EEI(HR). In addition, significant inverse relationships between Gross Motor Function Measure (GMFM) scores and within- (r = -0.61) and between-day (r = -0.58) CV values for net VO2 were detected. Viewed in concert, these data suggest that fairly stable within- and between-day measures of locomotor energy expenditure during level treadmill walking can be achieved in subjects with hemiplegic CP if testing is preceded by a short period of treadmill accommodation. However, children with greater motor dysfunction may require an extended period of treadmill accommodation to reduce trial-to-trial variability in walking energy use.

Assessment of RPE Signal Dominance at Slow to Moderate Walking Speeds in Children

The purpose of this investigation was to determine whether either the differentiated ratings of perceived exertion (RPE) for the legs (RPE-L) or chest (RPE-C) were higher than the overall body RPE (RPE-O) in children performing treadmill walking. A differentiated RPE that was higher than the RPE-O was considered the dominant perceptual signal. Thirty-one 10-year-old participants (16 boys, 15 girls) performed six separate 5-min bouts of level treadmill walking at different speeds. During each bout of exercise, RPEs were recorded using the modified Children’s OMNI Scale. Oxygen consumption (VO2), heart rate (HR), and ventilation (VE) were measured during Minutes 4 and 5 at each walking speed. VO2, HR, and VE increased as walking speed increased, as did perceived exertion. No differences were observed among RPE-O, RPE-L, and RPE-C at any speed. In addition, boys and girls exhibited similar responses for each perceptual and physiological variable. In conclusion, a dominant differentiated perceptual rating was not found at slow-to-moderate treadmill walking speeds for either boys or girls. Neither the respiratory–metabolic nor peripheral ratings of perceived exertion appeared to dominate the whole-body sensory-integration process in this sample.

Improving energy expenditure estimation for physical activity.

The purpose of this study was to validate the Intelligent Device for Energy Expenditure and Activity (IDEEA) for estimation of energy expenditure during a variety of activities. An additional aim was to improve the accuracy of the estimation of energy expenditure of physical activity based on second-by-second information of type, onset, and duration of activity. This study included two tests: a mask calorimetry test with 27 subjects [age = 33.7 +/- 13.8 (mean +/- SD) yr; BMI = 24.8 +/- 4.8 kg x m] and a respiratory chamber calorimetry test with 10 subjects (age = 32.9 +/- 12.4 yr; BMI = 26.1 +/- 5.6 kg x m). In the mask test, the subjects performed activities (sitting, standing, lying down, level treadmill walking, and running at different speeds) for 50-min durations. For the chamber test, subjects lived in the metabolic chamber for 23 h and performed three exercise sessions to compensate for the confined environment. The results showed significant correlations (P < 0.0001) between energy expenditure estimated by IDEEA and energy expenditure measured by the calorimeters with an accuracy >95%. After corrections for the decrease in sleeping metabolic rate, the estimation accuracy for the chamber test was increased by 1-96.2%, whereas the estimation accuracy for nighttime activity was significantly improved by 4-99%. IDEEA provides a suitable method for estimating the energy expenditure of physical activity. It provides both instantaneous and cumulative estimates of energy expenditure over a given period.

Longitudinal stratification of gait economy in young boys and girls: the locomotion energy and growth study.

The purpose of this study was to determine if the relative ordering of locomotor oxygen consumption ( VO(2)) values remains stable as healthy children age. Beginning at age 6 and ending at age 10, VO(2) during level treadmill walking and running was quantified in 15 boys and 18 girls who were tested on an annual basis. Following 30 min of treadmill accommodation to each exercise mode, subjects walked and ran for 5 min at 1.34 m s(-1) and 2.23 m s(-1), respectively. During the last 2 min of each 5-min stage, expired gas samples were collected and analyzed to quantify VO(2). For both walking (W) and running (R), 27% of subjects showed an average yearly change in VO(2) rank order of </=2 positions, 64% (W) and 61% (R) displayed a mean annual shift in VO(2) rank order of </=4 positions, and 85% exhibited a mean yearly fluctuation in W and R VO(2) rank order of </=6 positions. Reliability analysis of VO(2) responses across the 5-year testing period also yielded high coefficient alpha values for walking ( R=0.91) and running ( R=0.94). These results suggest that the relative ordering of individual gait VO(2) values remains quite stable in young children, indicating a physiological stratification that is fairly resistant to change during a period featuring increases in physical growth and varied exposure to different types of physical activity.

Contribution of cutaneous inputs from the hindpaw to the control of locomotion. I. Intact cats.

The goal of this study was to evaluate the role of hindpaw cutaneous feedback in the control of locomotion, by cutting some (in one cat) or all (in 2 cats) cutaneous nerves bilaterally at ankle level. Kinematic and electromyographic (EMG) recordings were obtained before and for several weeks after denervation during level and incline (15 degrees up and down) treadmill walking. Ladder walking and ground reaction forces were also documented sporadically. Early after the denervation (1-3 days), cats could not walk across a ladder, although deficits were small during level treadmill walking. Increased knee flexion velocity caused a 14% reduction in swing phase duration. EMG activity was consistently increased in knee, ankle, and toe flexors, and in at least one knee or ankle extensor. The adaptive changes during walking on the incline were much reduced after denervation. Ladder walking gradually recovered within 3-7 wk. By this time, level treadmill walking kinematics had completely returned to normal, but EMG activity in flexors remained above control. Incline walking improved but did not return to normal. Mediolateral ground reaction forces during overground walking were increased by 200%. It is concluded that in intact cats, cutaneous inputs contribute more to demanding situations such as walking on a ladder or on inclines than to level walking. Active adaptive mechanisms are likely involved given that the EMG locomotor pattern never returned to control level. The companion paper shows on the other hand that when the same cats are spinalized, these cutaneous inputs become critical for foot placement during locomotion.

ACCURACY OF THE FITSENSE FS-1 SPEEDOMETER DURING WALKING AND RUNNING

PURPOSE To examine the accuracy of the FitSense FS-1 Speedometer for estimating distance, speed, and energy expenditure (EE) during walking and running at different speeds and grades. METHODS The study was divided into three parts. Part I: The accuracy of the FitSense for estimating distance during walking and running was investigated during repeated 1600 m trials. Twenty-four participants volunteered for Part I. Part II: The accuracy of the FitSense for estimating speed and EE was examined during level treadmill walking (4.8, 6.4, and 8.0 km · hr−1) and running (8.0, 9.6, and 11.2 km·hr−1). Part III: The accuracy of the FitSense for estimating EE was examined during treadmill walking at a constant speed (4.8 km·hr−1) and selected grades (0.0, 2.5, 5.0, 7.5, and 10%). Twelve of the original 24 subjects completed Parts II and III. RESULTS Part I: The FitSense accurately estimated walking distance, but it underestimated running distance by an average of 3.5% (P = 0.016). Part II: The FitSense overestimated speed during walking and running at 8.0 km·hr−1 (P < 0.001). In addition, the device underestimated EE at two walking speeds (6.4 and 8.0 km·hr−1) (P < 0.01). No significant differences were found for speed or EE predictions while running on a level grade. Part III: The FitSense was unable to detect the rise in metabolic demand associated with increasing treadmill grades. CONCLUSION The FitSense FS-1 Speedometer was accurate for estimating distance and speed during level walking (4.8 and 6.4 km·hr−1) and running (9.6 and 11.2km·hr−1). However, the FitSense overestimated speed and underestimated EE in the transition between walking and running (8.0 km·hr−1). In addition, the FitSense underestimated EE during uphill walking.

Longitudinal profiles of oxygen uptake during treadmill walking in able-bodied children: the locomotion energy and growth study.

The purpose of this study was to document age-related changes in walking V(O(2)) in able-bodied boys and girls. Beginning at age 6 and ending at age 10, 23 children (14 girls, 9 boys) performed six 5-min bouts of level treadmill walking at 0.67, 0.89, 1.12, 1.34, 1.56, and 1.79 m s(-1) on an annual basis. Prior to data collection, subjects received 60 min of treadmill walking practice. During the last 2 min of each walking bout, a 2-min sample of expired air was collected in a meteorological balloon and analyzed to determine V(O(2)). Averaged across age, interindividual variation in V(O(2)) ranged from 32 to 41%. Repeated-measures analysis of variance demonstrated a speed by age interaction for V(O(2)), such that mean V(O(2)) rose (P< or = 0.05) across the five fastest speeds for 6-, 7-, 8-, and 10-year olds and increased over the entire speed range for 9-year olds. For all speeds, V(O(2)) decreased yearly from the ages of 6 to 8. When averaged across speeds, V(O(2)) was 27% higher for 6-year olds compared with 10-year olds. From a clinical perspective, access to longitudinal measurements of walking V(O(2)) in able-bodied children should be helpful in interpreting gait energy use in children with movement disorders and evaluating treatment strategies designed to reduce the aerobic demand of locomotion in youth with impaired mobility.

Impact of fluid replacement on heat storage while wearing protective clothing

This study used partitional calorimetry to determine the influence of fluid replacement on heat storage during uncompensable heat stress. Eight males performed either light (L; level treadmill walking at 0.97 m·s-1 (3.5 km·h-1) or heavy (H; 1.33 m·s-1 (4.8 km·h-1) at a 4% grade) exercise at 40°C and 30% relative humidity while wearing nuclear, biological and chemical (NBC) protective clothing. Subjects received either no fluid (NF), or 200 or 250 ml of fluid (F) as warm water at ~ 35°C immediately before and every 15 min during the L and H trials respectively. Similar reductions in heart rate were observed at both metabolic rates with F but rectal temperature responses were not different between F and NF. Tolerance time was extended during L/F (106.5±22.1 min) compared with L/NF (93.1±20.8 min) but fluid replacement had no influence during H (59.8±9.5 min and 58.3±11.1 min for F and NF respectively). Fluid replacement also had no effect on the rate of heat storage during L (108.2±20.6 W·m-2 and 111.0±22.6 W·m-2 for F and NF respectively) and H (172.5±11.5 W·m-2 and 182.1±15.8 W·m-2 for F and NF respectively). However, heat storage expressed per unit of mass was significantly increased during L/F (18.5±4.0 kJ·kg-1) compared with the other trials (16.3±4.8 kJ·kg-1, 16.6±3.0 kJ·kg-1 and 16.7±4.0 kJ·kg-1 for L/NF, H/F and H/NF respectively). It was concluded that fluid replacement does not alter the rate of heat storage during uncompensable heat stress but does increase the heat storage capacity during light exercise when tolerance times are > 60 min.

Metabolic accommodation of young children to treadmill walking.

Few data exist concerning the reproducibility of stable oxygen uptake (VO(2)) values during level treadmill walking in young able-bodied children. To address this issue, 41 able-bodied 6-year-olds (19 boys, 22 girls, X height=117.2+/-4.7 cm, X body mass=21.8+/-2.5 kg) were tested on two occasions. In session 1, subjects were familiarized with the laboratory environment and performed 5 min of level treadmill walking at 1.34 m s(-1). During session 2, each child completed 30 min (three 10-min trials) of level treadmill walking at 1.34 m s(-1). For each 10-min trial, mean VO(2) was determined by averaging VO(2) values obtained from analysis of two 2-min expired gas samples. While the mean VO(2) for trial 1 was higher than values recorded for trials 2 and 3, effect sizes corresponding to these differences were low (</=0.16). Average within subject coefficient of variation and intraclass reliability coefficient values for VO(2) across the three walking trials were 2. 0+/-1.5% and 0.96, respectively. Viewed collectively, these results suggests that among young able-bodied children, acceptably and reproducible stable VO(2) values during level treadmill walking can be obtained within 10 min if data collection is preceded by exposure to testing procedures and a brief period of treadmill walking practice.

KINEMATIC DATA OF THE LUMBAR REGION IN INCLINE TREADMILL WALKING

1687 Incline walking is used as a provocation test in low back pain patients and clinical gait analysis often includes the evaluation of trunk and pelvis motions in free level walking, however kinematic baseline data of the lumbar region in incline walking is missing. The present study compares trunk (T12) and pelvis (S1) motions in the sagittal, frontal and transverse planes of 22 healthy subjects (18♂, 4♀; ⊘=27.3 years) in level and incline(10%) treadmill walking using an 3-D-ultrasonic movement analysis system. Mean values for net angular displacements of the trunk and pelvis were calculated for each plane within the 5th and 95th percentile. Student t-test revealed significantly (p<0.01) higher amplitudes for T12 displacements in incline compared to level treadmill walking (frontal: 9.2 ° vs. 6.4 °; sagittal: 3.8 ° vs. 2.8 °; transverse: 4.1 ° vs. 2.6 °). No significant differences were detected for angular displacements of the pelvis. Crosscorrelation revealed almost identical time histories of falling and rising trends in T12 and S1 curves in incline and level walking in each plane(r=0.86 - 0.94, p<0.01). It could be stated that the phasic patterns in level walking are no different from that obtained for incline. The findings indicated that incline ambulation leads to increased angular displacements caused by increased oscillations of the upper lumbar region.

METABOLIC ACCOMMODATION OF YOUNG CHILDREN TO TREADMILL WALKING 1167

Few data exist concerning the time period required for young children to exhibit stable oxygen uptake (VO2) responses to treadmill walking. To address this issue, 46 6-year olds (25 girls, 21 boys; X height = 117.3± 4.7 cm; X body mass = 21.8 ± 2.6 kg) were tested on two occasions. In Visit 1, subjects were familiarized with the laboratory environment and performed 5 min of level treadmill walking at 1.34 m·s-1. During Visit 2, each child completed 30 min (three 10-min trials) of level treadmill walking at 1.34 m·s-1. Expired gas samples were collected via meteorological balloons from minutes 8 to 10 of each trial and analyzed to determine VO2. Data analysis revealed no significant difference (p < 0.05) in mean VO2(ml·kg-1·min-1) across trials (Trial 1 VO2= 19.4 ± 1.5; Trial 2 VO2 = 19.2 ± 1.5; Trial 3 VO2 = 19.1 ± 1.4). Average within-subject coefficient of variation in VO2 across the three walking trials was 2.5 ± 1.8%. These results suggest that among young children, stable VO2 values during level treadmill walking can be obtained within 10 min if data collection is preceded by exposure to testing procedures and a brief period of treadmill walking practice.

RELATIONSHIP BETWEEN PREFERRED AND ENERGETICALLY OPTIMAL WALKING SPEEDS IN YOUNG CHILDREN 93

In adults, the aerobic demand (˙VO2) required to walk a given distance is lowest at ≈1.3 m/s. It has also been shown that adults select walking speeds that minimize ˙VO2. To determine if this relationship exists in young children, 29 6-yr olds ([horizontal bar over]X height = 118.5 ± 3.8 cm; [horizontal bar over]X body mass = 21.9± 2.4 kg) completed 5-min level treadmill walking bouts at 6 speeds(0.67, 0.89, 1.12, 1.34, 1.56 and 1.79 m/s). ˙VO2 was quantified from expired gas samples collected during the last 2 min of each bout. Quadratic speed-VO2 curves were derived for each subject to predict the speed at which ˙VO2 was minimal. Preferred walking speed was also calculated from the average of at least 10 overground trials. Results indicated no significant difference (p > 0.05) between the most economical walking speed (MEWS) (1.28 ± 0.07 m/s) and the freely-chosen walking speed (1.30 ± 0.14 m/s). These findings reveal a similarity in MEWS between prepubescents and adults and suggest that, like adults, young children choose walking speeds that yield the lowest ˙VO2. From a theoretical perspective, our findings provide additional support for the notion that optimization of energy costs is a fundamental principle governing human locomotion.

Evaluation of the Pendant Oxygen-Conserving Nasal Cannula during Exercise

There is much recent evidence that patients with chronic pulmonary disease who are hypoxemic benefit from continuous therapy with oxygen. These benefits include reduction in symptoms of cor pulmonale, reduction in mortality, and improvement in quality of life. Oxygen therapy is very expensive, and steady-flow delivery of oxygen is wasteful, since almost the entire benefit of the oxygen presented to the patient occurs at the very beginning of inspiration. We previously described a conserver nasal cannula (CNC) which stores oxygen during exhalation for delivery during subsequent inspirations. The CNC achieves adequate arterial oxygen saturation (SaO2) at one fourth to one half of the flow in liters of steady-flow oxygen delivery. Because some patients found the mustache configuration objectionable, a pendant nasal cannula (PNC) was designed, displacing the reservoir off of the face and onto the anterior wall of the chest. While both cannulas require some breathing by nose to function, the PNC is more esthetically acceptable. No studies with exercise have been reported using the PNC. We evaluated the PNC during treadmill exercise in ten subjects with chronic obstructive pulmonary disease and hypoxemia on exercise. We compared the PNC with steady-flow oxygen during steady level treadmill walking sufficient to cause oxygen desaturation while breathing room air at oxygen presentations of 0.5 through 3.0 L/min. At comparable workloads the SaO2 achieved by PNC required one third of the oxygen flow required by steady-flow oxygen to achieve an equivalent SaO2. These differences were statistically significant (p less than 0.01). We conclude that the PNC provides effective delivery of oxygen during exercise, as well as at rest, while minimizing oxygen flow rate and thus substantially reducing the economic burden normally associated with supplemental oxygen delivery.

Changes in knee function associated with treadmill ambulation

A comparison of level walking, on a walkway and on a treadmill, was performed using ten normal subjects. Motion about the knee was measured using a triaxial electrogoniometer, and foot-floor contact patterns were recorded by means of four foot switches attached to the sole of each shoe. On the walkway, the data were collected with the subject moving at a comfortable walking speed. The treadmill was then set at the average velocity obtained on the walkway. Knee joint rotation in the coronal and transverse planes did not change significantly between the walkway and the treadmill. In the sagittal plane, significant differences were found for total motion ( p < 0.01), swing phase motion ( p < 0.01), knee position at heel strike ( p < 0.05), and maximum swing phase extension ( p < 0.01). A comparison of the foot-floor contact patterns between walkway and treadmill ambulation revealed reduced heel contact time, with an increase in toe contact while on the treadmill. It was concluded that sagittal plane knee kinematics during level treadmill walking differ significantly from level overground walking.

Transfers of mechanical energy within the total body and mechanical efficiency during treadmill walking.

The efficiency of human gait has been the subject of comment and speculation for some time. Biomechanically it has been shown that there are passive energy exchanges within body segments and between adjacent segments. The purposes of this paper were to measure and calculate how much of the segment energy changes can be attributed to muscular activity versus these passive exchange mechanisms, and to calculate the mechanical efficiency of overground walking based on the internal mechanical work. Six male subjects, matched for age, height and weight, were analysed during level treadmill walking at an average velocity of 1-54 -1 and a step length of 0-79m using an 11 segment planar biomechanical model. It was determined that the rate of doing internal work, both positive and negative, was about 165 W although the total observed work rate was 500 W. The rate of passive energy exchange within and between segments was 335 W. These results indicate that about two-thirds of the observed mechanical energy changes a...

The influence of exercise on atrial flutter

To study the effect of exercise on atrial flutter the electrocardiogram was recorded continuously before, during and after low level treadmill walking in twenty-two ambulatory patients. Atrial flutter rates increased during exercise testing in four patients. Improved A-V conduction with consequent higher ventricular rates occurred during exercise in thirteen subjects. One patient, with 4:1 conduction at rest, continued with 4:1 block throughout exercise testing, was believed to be over-digitalized. During the recovery period after exercise, ten patients transiently developed periods of Wenckebach A-V block. Walking exercise induced 1:1 conduction in six patients and was promoted by the following circumstances: 1) atrial rates of 250/min or less; 2) inadequate dosage of digitalis; and 3) the administration of quinidine. For the patient with chronic atrial flutter, treadmill testing provides a simple method for demonstrating the range of changes of A-V conduction and for deriving implications for appropriate drug therapy.

The Effects of 30% Oxygen on the Respiratory Response to Treadmill Exercise in Chronic Respiratory Failure

1. Minute ventilation, carbon dioxide output, and gas tensions, pH, lactate and pyruvate concentrations of arterial blood were measured in ten severely hypoxic bronchitic patients, both at rest and during slow level-treadmill walking, when breathing either air or 30% oxygen. 2. Hypoxaemia was aggravated by exercise, without change in the mean CO2 tension. Hypoxaemia was improved when 30% oxygen was breathed on exercise, but again there was no significant rise in the average arterial CO2 tension. 3. Arterial lactate concentrations, normal at rest in seven cases, were significantly increased in the last minute of exercise when breathing air, but were decreased by breathing oxygen on exercise in eight of nine cases. Arterial lactate/pyruvate ratios were not significantly changed by exercise during either air or oxygen breathing. 4. Both ventilation and CO2 output fell consistently when exercise was done breathing 30% oxygen, despite random allocation of the order of air and oxygen breathing, and the maintenance of a constant treadmill speed. 5. It is concluded that an intact chemoreceptor drive to ventilation mediated this fall in minute volume. The fall in CO2 output on exercise with oxygen does not arise from technical errors, changes in body CO2 stores, or the high work of breathing, and remains unexplained.

Oxygen uptake during maximal treadmill and bicycle exercise.

Oxygen uptake during maximal treadmill and bicycle exercise.

Limitations to the prediction of maximum oxygen intake from cardiac frequency measurements.

Limitations to the prediction of maximum oxygen intake from cardiac frequency measurements.