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Concept: Stairway

204

Stairway climbing provides a ubiquitous and inconspicuous method of burning calories. While typically two strategies are employed for climbing stairs, climbing one stair step per stride or two steps per stride, research to date has not clarified if there are any differences in energy expenditure between them. Fourteen participants took part in two stair climbing trials whereby measures of heart rate were used to estimate energy expenditure during stairway ascent at speeds chosen by the participants. The relationship between rate of oxygen consumption ([Formula: see text]) and heart rate was calibrated for each participant using an inclined treadmill. The trials involved climbing up and down a 14.05 m high stairway, either ascending one step per stride or ascending two stair steps per stride. Single-step climbing used 8.5±0.1 kcal min(-1), whereas double step climbing used 9.2±0.1 kcal min(-1). These estimations are similar to equivalent measures in all previous studies, which have all directly measured [Formula: see text] The present study findings indicate that (1) treadmill-calibrated heart rate recordings can be used as a valid alternative to respirometry to ascertain rate of energy expenditure during stair climbing; (2) two step climbing invokes a higher rate of energy expenditure; however, one step climbing is energetically more expensive in total over the entirety of a stairway. Therefore to expend the maximum number of calories when climbing a set of stairs the single-step strategy is better.

Concepts: Cost, Stairway

81

Here we show that novel, energy-recycling stairs reduce the amount of work required for humans to both ascend and descend stairs. Our low-power, interactive, and modular steps can be placed on existing staircases, storing energy during stair descent and returning that energy to the user during stair ascent. Energy is recycled through event-triggered latching and unlatching of passive springs without the use of powered actuators. When ascending the energy-recycling stairs, naive users generated 17.4 ± 6.9% less positive work with their leading legs compared to conventional stairs, with the knee joint positive work reduced by 37.7 ± 10.5%. Users also generated 21.9 ± 17.8% less negative work with their trailing legs during stair descent, with ankle joint negative work reduced by 26.0 ± 15.9%. Our low-power energy-recycling stairs have the potential to assist people with mobility impairments during stair negotiation on existing staircases.

Concepts: Human anatomy, Human leg, Joint, Knee, Joints, Stairway, Energy, Potential energy

28

To evaluate whether increased laxity of the knee during daily physical activities such as stair climbing is associated with progression of knee joint osteoarthritis (OA).

Concepts: Medicine, Joints, Stairway, Synovial joint, Cartilage, Osteoarthritis, Joint, Knee

27

Pregnant women experience numerous physical alterations during pregnancy which may place them at an increased risk of falls. The purpose of this study was to examine ground reaction forces (GRFs) during staircase locomotion in pregnant and non-pregnant women. METHODS: Data were collected on 29 pregnant women in their second and third trimesters, and on 40 control women. Subjects walked at their freely chosen speeds during stair ascent and descent. A force plate imbedded in the second stair, but structurally independent of the staircase, was used to collect GRF data (1080Hz). A marker placed on the L3/L4 spinal segment was used to determine ascent and descent velocity from a motion-capture system. In the statistical analyses, trimester (control, second trimester, third trimester) and subject were the independent variables. Stance time and ascent/descent velocity were analyzed with an ANOVA. Mediolateral excursion of the COP during the step was analyzed with an ANCOVA. The GRFs were categorized into anterioposterior, mediolateral, and vertical forces. A two factor MANCOVA (subject, trimester) was performed on each GRF category. Mass and velocity served as covariates in each analysis (a=0.05). RESULTS: The mediolateral excursion of the COP during ascent was greater in the third trimester (p=0.04). The anterioposterior braking impulse was greater in both ascent (p=0.01) and descent (p=0.01) during pregnancy. The vertical GRF loading rate during descent was greater in pregnant women than in controls (p=0.04). CONCLUSION: These alterations are likely related to increased instability during stairway walking and could contribute to increased fall risk during pregnancy.

Concepts: Reaction, Force, Walking, Stairway, Childbirth, Ground reaction force, Trimester, Pregnancy

8

Several studies have demonstrated that point-of-choice prompts modestly increase stair use (i.e., incidental physical activity) in many public places, but evidence of effectiveness in airport settings is weak. Furthermore, evaluating the effects of past physical activity on stair use and on point-of-choice prompts to increase stair use is lacking. The purpose of this study was to evaluate the influence of sign prompts and participant factors including past physical activity on stair ascent in an airport setting. We used a quasi-experimental design, systematically introducing and removing sign prompts daily across 22 days at the San Diego International Airport. Intercept interviewers recruited stair and escalator ascenders (N = 1091; 33.0% interview refusal rate) of the only stairs/escalators providing access to Terminal 1 from the parking lot. A 13-item questionnaire about demographics, physical activity, health behavior, and contextual factors provided data not available in nearly all other stair use studies. We examined the effects of signs and self-reported covariates using multivariable logistic regression analyses, and tested whether physical activity and other covariates modified the intervention effect. Adjusting for all significant covariates, prompts increased the odds of stair use (odds ratio 3.67; p < .001). Past participation in vigorous physical activity increased the odds of stair use by 1.62 (p = 0.001). None of the covariates moderated the intervention effect. In conclusion, vigorous physical activity and correlates of physical activity were related to stair use in expected directions, but did not modify the effect of the intervention. This indicates that the effects of point-of-choice prompts are independent of past physical activity, making them effective interventions for active adults and the higher risk population of inactive adults. Signs can prompt stair use in an airport setting and might be employed at most public stairs to increase rates of incidental physical activity and contribute to overall improvements in population health.

Concepts: Odds ratio, Demography, Southwest Airlines, Logit, Effect, Stairway, Effectiveness, Regression analysis

1

Background. Fibromyalgia is a chronic disease characterized by widespread pain and other associated symptoms. It has a relevant impact on physical fitness and the ability to perform daily living tasks. The objective of the study was to analyze the step-by-step-performance and the trunk tilt of women with fibromyalgia in the 10-step stair climbing test compared with healthy controls. Methods. A cross-sectional study was carried out. Twelve women suffering from fibromyalgia and eight healthy controls were recruited from a local association. Participants were asked to climb 10 stairs without carrying a load and 10 stairs carrying a load of 5 kg in each hand. Mediolateral trunk tilt was assessed using the “Functional Assessment of Biomechanics (FAB)” wireless motion capture device, and the time between steps was assessed via weight-bearing insoles. Results. Trunk tilt in the stair-climbing task carrying a load was significantly higher in women with fibromyalgia when compared to the healthy controls (2.31 (0.63) vs. 1.69 (0.51) respectively). The effect of carrying a load was significantly higher for women with fibromyalgia compared with healthy controls at the intermediate and final part of the task. Discussion. Trunk tilt during stair climbing while carrying a load was higher in women with FM, which could increase the risk of falling. Additionally, women with FM experienced a higher pace slowdown as a consequence of the load, which supports the need of including specific strength and resistance training to physical therapies for this population.

Concepts: Exercise, Chronic, Task, Stairway, Specific strength, Strength training, Epidemiology, Medicine

1

Perception of hill slant is exaggerated in explicit awareness. Proffitt (Perspectives on Psychological Science 1:110-122, 2006) argued that explicit perception of the slant of a climb allows individuals to plan locomotion in keeping with their available locomotor resources, yet no behavioral evidence supports this contention. Pedestrians in a built environment can often avoid climbing stairs, the man-made equivalent of steep hills, by choosing an adjacent escalator. Stair climbing is avoided more by women, the old, and the overweight than by their comparators. Two studies tested perceived steepness of the stairs as a cue that promotes this avoidance. In the first study, participants estimated the steepness of a staircase in a train station (n = 269). Sex, age, height, and weight were recorded. Women, older individuals, and those who were heavier and shorter reported the staircase as steeper than did their comparison groups. In a follow-up study in a shopping mall, pedestrians were recruited from those who chose the stairs and those who avoided them, with the samples stratified for sex, age, and weight status. Participants (n = 229) estimated the steepness of a life-sized image of the stairs they had just encountered, presented on the wall of a vacant shop in the mall. Pedestrians who avoided stair climbing by choosing the escalator reported the stairs as steeper even when demographic differences were controlled. Perceived steepness may to be a contextual cue that pedestrians use to avoid stair climbing when an alternative is available.

Concepts: Stairways, Differential calculus, Climbing, Stairway, Locomotion, Shopping mall, Psychology

1

Although running stairs is often used in sport conditioning programs, at present, little research has examined the effect of stair climb training on sprint power. The purpose of this study was to investigate the effects of running stairs either one-stair (1S) or two-stairs (2S) at a time on power. Fourteen male college track & field athletes were randomized into three groups; 1S, 2S, or control ©. All groups were pre-and post-tested for 1S, 2S, and 40 meter sprint split times. The 1S and 2S groups trained twice per week, for four weeks, performing ten sets of climbing 68 total stairs with two-and-a-half minutes rest between trials. The greatest power values (watts) from pre & post stairs and sprint splits were used for statistical analyses. There was a significant (p<0.05) interaction of group x time for stair climb. The 1S group increased power for the 1S test (pre-1492.89 ± 123.76 ; post-1647.41 ± 73.65) with no change in the 2S test (pre-2428.80 ± 414.81; post-2430.32 ± 154.90) while the 2S group increased power for the 2S test (pre-2343.73 ± 317.50; post-2646.17 ± 305.43) with no change in the 1S test (pre-1516.69 ± 210.64; post-1529.38 ± 236.69). The C group showed no change in either stair test (1S pre-1403.35 ± 238.67; post-1384.38 ± 153.32, 2S pre-2285.93 ± 345.03; post-2261.85 ± 356.88). There were no significant interactions or main effects for any sprint split power (40m pre-5337.13 ± 611.86; post-5318.68 ± 586.24).Therefore, stair climb training either one-or two-at-a-time did not affect 40m sprint split power but increased power for the specific stair training type. Coaches should choose the number of stairs that are similar in time and power output to sprint training.

Concepts: Split, Stairway, Statistical significance, Statistics, Effect, Affect

1

: Purpose: To investigate neuromuscular control of the knee during stair descent among female adolescents with Patellofemoral Pain (PFP) and report its association with self-reported clinical status assessed by the Knee injury and Osteoarthritis Outcome Score (KOOS).Methods: Fifty-seven previously untreated female adolescents diagnosed with PFP aged 15 to 19 years were recruited from schools. The control group consisted of 29 age-matched healthy female adolescents. Bipolar surface electrodes were placed on VM and VL and an electronic knee goniometer was placed at the knee to collect knee flexion/extension kinematics. The participants walked down a stairway consisting of 24 steps at their normal pace. Sample Entropy was used to quantify the complexity of the time series from surface electromyography (sEMG) and kinematics during the stance phase. Self-reported clinical status was assessed by the KOOS and maximal quadriceps torque measured using strap-mounted handheld dynamometry.Results: Female adolescents with PFP were characterized by altered neuromuscular knee control during stair descent, lower maximal quadriceps torque, and poorer KOOS scores across all five domains. Furthermore, a positive association was found between the complexity of sEMG from VL and self-reported pain determined by KOOSpain indicating larger impairments in neuromuscular knee control among those with the highest pain levels.Conclusion: The current findings show that female adolescents with PFP are characterized by altered neuromuscular control of the knee during stair descent and lower maximal quadriceps torque. These results suggest that rehabilitation is needed, and should focus on restoring neuromuscular control and muscle strength.

Concepts: Quadriceps femoris muscle, Controlling for a variable, Scientific control, Stairway, Knee, Energy, Muscle, Electromyography

1

Although the visual system is known to provide relevant information to guide stair locomotion, there is less understanding of the specific contributions of foveal and peripheral visual field information. The present study investigated the specific role of foveal vision during stair locomotion and ground-stairs transitions by using a dual-task paradigm to influence the ability to rely on foveal vision. Fifteen healthy adults (26.9±3.3 years; 8 females) ascended a 7-step staircase under four conditions: no secondary tasks (CONTROL); gaze fixation on a fixed target located at the end of the pathway (TARGET); visual reaction time task (VRT); and auditory reaction time task (ART). Gaze fixations towards stair features were significantly reduced in TARGET and VRT compared to CONTROL and ART. Despite the reduced fixations, participants were able to successfully ascend stairs and rarely used the handrail. Step time was increased during VRT compared to CONTROL in most stair steps. Navigating on the transition steps did not require more gaze fixations than the middle steps. However, reaction time tended to increase during locomotion on transitions suggesting additional executive demands during this phase. These findings suggest that foveal vision may not be an essential source of visual information regarding stair features to guide stair walking, despite the unique control challenges at transition phases as highlighted by phase-specific challenges in dual-tasking. Instead, the tendency to look at the steps in usual conditions likely provides a stable reference frame for extraction of visual information regarding step features from the entire visual field.

Concepts: Book of Optics, Optic nerve, Visual perception, Visual field, Handrail, Baluster, Visual system, Stairway