The metabolic changes associated with the addition of 4 months of resistive exercise to an existing aerobic exercise program (AEX+RT, n = 7) were compared to a maintenance aerobic exercise program (AEX, n = 8) in overweight, older men. The subjects in this study had recently completed a 6-month aerobic exercise program (treadmill walking, 45 min/d, 2 d/wk). The AEX+RT group added 6 exercises on upper- and lower-body pneumatic-resistance machines (2 sets, 15 repetitions each, 2 d/wk) to an aerobic exercise program at ≥ 70% heart rate reserve for 30–40 min, 2 d/wk on treadmill, while the AEX group continued the same maintenance treadmill AEX program. There were no baseline differences in body weight, VO2max, or glucose metabolism between groups. The AEX+RT group increased upper- and lower-extremity strength by 28 ± 4% and 46 ± 6%, respectively (p < .05), despite a 9% decrease in VO2max (p < .05). VO2max did not change in the AEX group. There was no change in the fasting glucose or insulin levels, or the 3-h glucose responses to an oral glucose load in either group. The insulin responses decreased by 25 ± 4% in the AEX+RT group (p < .01) but did not change in the AEX group. In conclusion, the addition of resistive exercise training to an existing aerobic exercise program may improve insulin sensitivity in overweight, older men, and thus prevent the development of type 2 diabetes.
Cynthia M. Ferrara, Susan H. McCrone, David Brendle, Alice S. Ryan and Andrew P. Goldberg
Ya-Ting Yang, Yasuyuki Yoshida, Tibor Hortobágyi and Shuji Suzuki
We determined the angular range of motion and the relative timing of displacement in the thorax, lumbar spine, and pelvis in the transverse plane during treadmill walking at three velocities. Nine healthy young females walked on a treadmill for three minutes at 0.40, 0.93, and 1.47 m/s. The position of seven reflective markers and three rigs placed on the thorax, lumbar spine, and pelvis were recorded at 200 Hz by an eight-camera motion capture system. As gait velocity increased, stride length increased, cycle time decreased, and angular displacement in the thorax and L1 decreased but increased at the pelvis and L5 (all P < .05). The time of maximal angular rotation occurred in the following sequence: pelvis, L5, L3, L1, and thorax (P < .001). The thorax and L1 and L3 were in-phase for shorter duration as gait velocity increased, and this reduction was especially large, approx. 32% (P < .05), between thorax and pelvis. As gait velocity increased, the pelvis rotated earlier, causing the shortening of in-phase duration between thorax and pelvis. These data suggest that, as gait velocity increases, pelvis rotation dictates trunk rotation in the transverse plane during gait in healthy young females.
Randall J. Bergman, Justin W. Spellman, Michael E. Hall and Shawn M. Bergman
This study examined the validity of a selected free pedometer application (iPedometer; IP) for the iPhone that could be used to assess physical activity.
Twenty college students (10 men, 10 women; mean age: 21.85 ± 1.57 yrs) wore an iPhone at 3 locations (pocket, waist, arm) and a StepWatch 3 Step Activity Monitor (SW) on their right ankle while walking on a treadmill at 5 different speeds (54, 67, 80, 94, 107 m·min−1). A research assistant counted steps with a tally counter (TC).
Statistical significance between the TC, SW, and IP was found during every condition except IP in the pocket at 107 m·min−1 (F 2,38 = .64, P = .54). Correlations involving the IP revealed only 1 positive correlation (IP on arm at 54 m·min−1) for any of the conditions (r = .46, P = .05).
The IP application was not accurate in counting steps and recorded significantly lower step counts than the SW and TC. Thus, the free pedometer application used is not a valid instrument for monitoring activity during treadmill walking.
Ann F. Maliszewski, Patty S. Freedson, Chris J. Ebbeling, Jill Crussemeyer and Kari B. Kastango
The Caltrac accelerometer functions as either an activity monitor that provides activity counts based on vertical acceleration as the individual moves about, or as a calorie counter in which the acceleration units are used in conjunction with body size, age, and sex to estimate energy expenditure. This study compared VO2 based energy expenditure with Caltrac estimated energy expenditure during three speeds of treadmill walking in children and adults. It also tested the validity of the Caltrac to differentiate between high and low levels of walking activity (activity counts). Ten boys and 10 men completed three randomly assigned walks while oxygen consumption was monitored and Caltrac estimates were obtained. The results indicate that the Caltrac does not accurately predict energy expenditure for boys and men across the three speeds of walking. Although there were no significant differences between actual and predicted energy expenditure values, the standard errors of estimate were high (17-25%) and the only significant correlation was found for men at the fastest walking speed (r=.81). However, the 95% confidence intervals of the activity counts and energy expenditure estimates from the Caltrac support its use as an activity monitor during walking.
Dinesh John, David Bassett, Dixie Thompson, Jeffrey Fairbrother and Debora Baldwin
Although using a treadmill workstation may change the sedentary nature of desk jobs, it is unknown if walking while working affects performance on office-work related tasks.
To assess differences between seated and walking conditions on motor skills and cognitive function tests.
Eleven males (24.6 ± 3.5 y) and 9 females (27.0 ± 3.9 y) completed a test battery to assess selective attention and processing speed, typing speed, mouse clicking/drag-and-drop speed, and GRE math and reading comprehension. Testing was performed under seated and walking conditions on 2 separate days using a counterbalanced, within subjects design. Participants did not have an acclimation period before the walking condition.
Paired t tests (P < .05) revealed that in the seated condition, completion times were shorter for mouse clicking (26.6 ± 3.0 vs. 28.2 ± 2.5s) and drag-and-drop (40.3 ± 4.2 vs. 43.9 ± 2.5s) tests, typing speed was greater (40.2 ± 9.1 vs. 36.9 ± 10.2 adjusted words · min−1), and math scores were better (71.4 ± 15.2 vs. 64.3 ± 13.4%). There were no significant differences between conditions in selective attention and processing speed or in reading comprehension.
Compared with the seated condition, treadmill walking caused a 6% to 11% decrease in measures of fine motor skills and math problem solving, but did not affect selective attention and processing speed or reading comprehension.
Meaghan Nolan, J. Ross Mitchell and Patricia K. Doyle-Baker
The popularity of smartphones has led researchers to ask if they can replace traditional tools for assessing free-living physical activity. Our purpose was to establish proof-of-concept that a smartphone could record acceleration during physical activity, and those data could be modeled to predict activity type (walking or running), speed (km·h−1), and energy expenditure (METs).
An application to record and e-mail accelerations was developed for the Apple iPhone®/iPod Touch®. Twentyfive healthy adults performed treadmill walking (4.0 km·h−1 to 7.2 km·h−1) and running (8.1 km·h−1 to 11.3 km·h−1) wearing the device. Criterion energy expenditure measurements were collected via metabolic cart.
Activity type was classified with 99% accuracy. Speed was predicted with a bias of 0.02 km·h−1 (SEE: 0.57 km·h−1) for walking, –0.03 km·h−1 (SEE: 1.02 km·h−1) for running. Energy expenditure was predicted with a bias of 0.35 METs (SEE: 0.75 METs) for walking, –0.43 METs (SEE: 1.24 METs) for running.
Our results suggest that an iPhone/iPod Touch can predict aspects of locomotion with accuracy similar to other accelerometer-based tools. Future studies may leverage this and the additional features of smartphones to improve data collection and compliance.
Leslie Peacock, Allan Hewitt, David A. Rowe and Rona Sutherland
The study investigated (a) walking intensity (stride rate and energy expenditure) under three speed instructions; (b) associations between stride rate, age, height, and walking intensity; and (c) synchronization between stride rate and music tempo during overground walking in a population of healthy older adults.
Twenty-nine participants completed 3 treadmill-walking trials and 3 overground-walking trials at 3 self-selected speeds. Treadmill VO2 was measured using indirect calorimetry. Stride rate and music tempo were recorded during overground-walking trials.
Mean stride rate exceeded minimum thresholds for moderate to vigorous physical activity (MVPA) under slow (111.41 ± 11.93), medium (118.17 ± 11.43), and fast (123.79 ± 11.61) instructions. A multilevel model showed that stride rate, age, and height have a significant effect (p < .01) on walking intensity.
Healthy older adults achieve MVPA with stride rates that fall below published minima for MVPA. Stride rate, age, and height are significant predictors of energy expenditure in this population. Music can be a useful way to guide walking cadence.
Mark Abel, James Hannon, David Mullineaux and Aaron Beighle
Current recommendations call for adults to be physically active at moderate and/or vigorous intensities. Given the popularity of walking and running, the use of step rates may provide a practical and inexpensive means to evaluate ambulatory intensity. Thus, the purpose of this study was to identify step rate thresholds that correspond to various intensity classifications.
Oxygen consumption was measured at rest and during 10 minute treadmill walking and running trials at 6 standardized speeds (54, 80, 107, 134, 161, and 188 m·min-1) in 9 men and 10 women (28.8 ± 6.8 yrs). Two observers counted the participants’ steps at each treadmill speed. Linear and nonlinear regression analyses were used to develop prediction equations to ascertain step rate thresholds at various intensities.
Nonlinear regression analysis of the metabolic cost versus step rates across all treadmill speeds yielded the highest R 2 values for men (R 2 = .91) and women (R 2 = .79). For men, the nonlinear analysis yielded 94 and 125 step·min-1 for moderate and vigorous intensities, respectively. For women, 99 and 135 step·min-1 corresponded with moderate and vigorous intensities, respectively.
Promoting a step rate of 100 step·min-1 may serve as a practical public health recommendation to exercise at moderate intensity.
David A. Rowe, David McMinn, Leslie Peacock, Arjan W. P. Buis, Rona Sutherland, Emma Henderson and Allan Hewitt
Walking cadence has shown promise for estimating walking intensity in healthy adults. Auditory cues have been shown to improve gait symmetry in populations with movement disorders. We investigated the walking cadence-energy expenditure relationship in unilateral transtibial amputees (TTAs), and the potential of music cues for regulating walking cadence and improving gait symmetry.
Seventeen unilateral TTAs performed 2 5-min treadmill walking trials, followed by 2 5-min overground walking trials (self-regulated “brisk” intensity, and while attempting to match a moderate-tempo digital music cue).
Walking cadence significantly (P < .001) and accurately (R 2 = .55, SEE = 0.50 METs) predicted energy expenditure, and a cadence of 86 steps·min−1 was equivalent to a 3-MET intensity. Although most participants were able to match cadence to prescribed music tempo, gait symmetry was not improved during the music-guided condition, compared with the self-regulated condition.
This is the first study to investigate the utility of walking cadence for monitoring and regulating walking intensity in adults with lower limb prosthesis. Cadence has similar or superior accuracy as an indicator of walking intensity in this population, compared with the general population, and adults with a unilateral TTA are capable of walking at moderate intensity and above for meaningful bouts of time.
Timo Rantalainen, Nicolas H. Hart, Sophia Nimphius and Daniel W. Wundersitz
Inertial measurement units (IMU) provide a convenient tool for gait stability assessment. However, it is unclear how various gait characteristics relate to each other and whether gait characteristics can be obtained from resultant acceleration. Therefore, step duration variability was measured in treadmill walking from 39 young ambulant volunteers (age 24.2 [± 2.5] y; height 1.79 [± 0.09] m; mass 71.6 [± 12.0] kg) using motion capture. Accelerations and gyrations were simultaneously recorded with an IMU. Harmonic ratio, maximum Lyapunov exponents, and multiscale sample entropy (MSE) were calculated. Step duration variability was positively associated with MSE with coarseness levels = 3–6 (r = –.33 to –.42, P ≤ .045). Harmonic ratio and MSE with all coarseness levels were negatively associated (r = –.45 to –.57, P ≤ .004). The MSE with coarseness level = 2 was negatively associated with short-term maximum Lyapunov exponents (r = –.32, P = .047). The agreement between resultant and vertical acceleration derived gait characteristics was excellent (ICC = 0.97–0.99). In conclusion, MSE with varying coarseness levels was associated with the other gait characteristics evaluated in the study. Resultant and vertical acceleration derived results had excellent agreement, which suggests that resultant acceleration is a viable alternative to considering the acceleration dimensions independently.