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.
Leslie N. Silk, David A. Greene, and Michael K. Baker
Research examining the preventative effects of calcium and vitamin D supplementation has focused on children and females, leaving the effects on male bone mineral density (BMD) largely unexplored. Thus, the aim of this systematic review and meta-analysis is to examine the efficacy of calcium supplementation, with or without vitamin D for improving BMD in healthy males. Medline, EMBASE, SPORTDiscus, Academic Search Complete, CINHAHL Plus and PubMed databases were searched for studies including healthy males which provided participants calcium supplementation with or without vitamin D and used changes to BMD as the primary outcome measure. Between trial standardized mean differences of percentage change from baseline in BMD of femoral neck, lumbar spine, total body and total hip sites were calculated. Nine studies were included in the systematic review with six references totaling 867 participants contributing to the meta-analysis. Significant pooled effects size (ES) for comparison between supplementation and control groups were found at all sites included in the meta-analysis. The largest effect was found in total body (ES = 0.644; 95% CI = 0.406–0.883; p < .001), followed by total hip (ES = 0.483, 95% CI= 0.255–0.711, p < .001), femoral neck (ES = 0.402, 95% CI = 0.233–0.570, p = .000) and lumbar spine (ES = 0.306, 95% CI = 0.173–0.440, p < .001). Limited evidence appears to support the use of calcium and vitamin D supplementation for improving BMD in older males. There is a need for high quality randomized controlled trials, especially in younger and middle-aged male cohorts and athletic populations to determine whether supplementation provides a preventative benefit.
Henry C. Lukaski, William W. Bolonchuk, Leslie M. Klevay, David B. Milne, and Harold H. Sandstead
In a pilot study, performance measures and mineral metabolism were assessed in 3 male endurance cyclists who consumed isoenergetic, isonitrogenous diets for 28-day periods in a randomized, crossover design in which dietary carbohydrate, polyunsaturated, or saturated fat contributed about 50% of daily energy intake. Peak aerobic capacity [62 ml/(kg · min)] was unaffected by diet. Endurance capacity at 70–75% peak aerobic capacity decreased with the polyunsaturated fat diet. Copper retention tended to be positive only with saturated fat. Less iron and zinc were retained (intake – losses), and fecal losses of these minerals increased with the polyunsaturated fat. Blood biochemical measures of trace element nutritional status were unaffected by diet, except serum ferritin, which tended to decrease during consumption of the polyunsaturated fat diet. These preliminary results suggest that diets high in polyunsaturated fat, particularly linoleic acid, impair absorption and utilization of iron and zinc, and possibly magnesium, and may reduce endurance performance.
Mary O. Hearst, John R. Sirard, Leslie Lytle, Donald R. Dengel, and David Berrigan
The association of physical activity (PA), measured 3 ways, and biomarkers were compared in a sample of adolescents.
PA data were collected on 2 cohorts of adolescents (N = 700) in the Twin Cities, Minnesota, 2007–2008. PA was measured using 2 survey questions [Modified Activity Questionnaire (MAQ)], the 3-Day Physical Activity Recall (3DPAR), and accelerometers. Biomarkers included systolic (SBP) and diastolic blood pressure (DBP), lipids, percent body fat (%BF), and body mass index (BMI) percentile. Bivariate relationships among PA measures and biomarkers were examined followed by generalized estimating equations for multivariate analysis.
The 3 measures were significantly correlated with each other (r = .22–.36, P < .001). Controlling for study, puberty, age, and gender, all 3 PA measures were associated with %BF (MAQ = −1.93, P < .001; 3DPAR = −1.64, P < .001; accelerometer = −1.06, P = .001). The MAQ and accelerometers were negatively associated with BMI percentile. None of the 3 PA measures were significantly associated with SBP or lipids. The percentage of adolescents meeting the national PA recommendations varied by instrument.
All 3 instruments demonstrated consistent findings when estimating associations with %BF, but were different for prevalence estimates. Researchers must carefully consider the intended use of PA data when choosing a measurement instrument.
Michael Koh, Leslie Jennings, Bruce Elliott, and David Lloyd
The Yurchenko layout vault is the base vault from which more advanced forms of the Yurchenko family of vaults have evolved. The purpose of the study was to predict an individual’s optimal Yurchenko layout vault by modifying selected critical mechanical variables. The gymnast’s current performance characteristics were determined using the Peak-Motus video analysis system. Body segment parameters were determined using the elliptical zone mathematical modeling technique of Jensen (1978). A 5-segment computer simulation model was personalized for the gymnast comprising the hands, upper limbs, upper trunk, lower trunk, and lower limbs. Symmetry was assumed, as the motion was planar in nature. An objective function was identified which translated the subjective points-evaluation scheme of the Federation of International Gymnastics (FIG) Code of Points to an analytic expression that was mathematically tractable. The objective function was composed of performance variables that, if maximized, would result in minimal points being deducted and bonus points being allocated. A combined optimal control and optimal parameter selection approach was applied to the model to determine an optimum technique. The predicted optimal vault displayed greater postflight amplitude and angular momentum when compared with the gymnast’s best trial performance. Increased angular velocity, and consequently greater angular momentum at impact and greater shoulder flexion angle at impact with the horse, were related with this optimum technique. The impact phase therefore serves to increase the angular momentum during horse contact. Since the optimized parameters at impact with the horse were within the accepted physical capacity limits observed for the individual, the predicted vault is viable.
James Dimmock, David Simich, Timothy Budden, Leslie Podlog, Mark Beauchamp, and Ben Jackson
Across 2 studies, the authors explored reactance effects to overexaggerated claims and controlling language in exercise messaging. In Study 1, participants received either a message exaggerating the benefits of an upcoming exercise session or no message. They subsequently undertook a mundane exercise session led by an instructor, which was either need supportive or “realistically controlling.” Relative to no-message participants, those who had read the message reported less positive evaluations of the session. These results were observed despite participants in the message condition holding more positive presession expectations, and the effect was apparent even for those who received need-supportive instruction. In Study 2, participants read an advertisement that was written in either autonomy-supportive language or controlling language. Despite reporting comparable expectations, participants who received a controlling-language message reported significantly greater anger and freedom threat—factors commonly linked to contrast effects. These studies highlight the operation of message-driven contrast effects in exercise.
David B. Creel, Leslie M. Schuh, Robert L. Newton Jr, Joseph J. Stote, and Brenda M. Cacucci
Background: Few studies have quantified cardiorespiratory fitness among individuals seeking bariatric surgery. Treadmill testing allows researchers to determine exercise capacity through metabolic equivalents. These findings can assist clinicians in understanding patients’ capabilities to carry out various activities of daily living. The purpose of this study was to determine exercise tolerance and the variables associated with fitness, among individuals seeking bariatric surgery. Methods: Bariatric surgery candidates completed submaximal treadmill testing and provided ratings of perceived exertion. Each participant also completed questionnaires related to history of exercise, mood, and perceived barriers/benefits of exercise. Results: Over half of participants reported that exercise was “hard to very hard” before reaching 70% of heart rate reserve, and one-third of participants reported that exercise was “moderately hard” at less than 3 metabolic equivalents (light activity). Body mass index and age accounted for the majority of the variance in exercise tolerance, but athletic history, employment status, and perceived health benefits also contributed. Perceived benefit scores were higher than barrier scores. Conclusion: Categories commonly used to describe moderate-intensity exercise (3–6 metabolic equivalents) do not coincide with perceptions of intensity among many bariatric surgery candidates, especially those with a body mass index of 50 or more.
Mark Loftin, Patricia Strikmiller, Barbara Warren, Leann Myers, Leslie Schroth, James Pittman, David Harsha, and Melinda Sothern
Peak cardiorespiratory responses, physical activity patterns, and the association of VO2peak and physical activity were examined in 16 elementary (ES) and 16 high school (HS) females. Peak responses were assessed during treadmill running, and physical activity patterns were examined over two 12-hour weekdays. Results indicated similar relative VO2peak responses between groups (ES: M = 46.8 ml · kg−1 · min−1;HS:M = 46.6 ml · kg−1 · min−1). No statistical differences (p ≤ .05) were noted when moderate to vigorous physical activity (MVPA) and vigorous physical activity (VPA) were compared. Also, a three-way (Group × HR level × Sustained minutes) ANOVA revealed no statistical differences. A median correlation (r = .27) was found from 8 independent correlations of habitual physical activity and VO2peak. ES and HS appeared similar in regard to VO2peak, accumulative and sustained MVPA and VPA. Low levels of sustained MVPA and VPA (≥ 10 min) were evident in both groups.
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.