Effect of single-radius design on in vivo kinematics during stair activities after total knee arthroplasty.

BACKGROUND: The single-radius design is one of the major total knee arthroplasty (TKA) designs and widely used all over the world. The objective of this study was to compare in vivo kinematics between the anteroposterior (AP) single-radius design with mediolateral (ML) single-radius (Non Restricted Geometry; NRG) and ML dual-radius (Triathlon) during stair activities. METHODS: A total of 21 knees in 18 patients (NRG group: 10 knees in 7 patients, Triathlon group: 11 knees in 11 patients) with a clinically successful posterior stabilized TKA were examined. Under fluoroscopic surveillance, each patient performed stair ascending and descending motions. In vivo kinematics were analyzed using 2D/3D registration technique. The knee flexion angle, rotation angle, varus-valgus angle, AP translation of the femorotibial contact point for both the medial and lateral sides of the knee, and post-cam engagement were evaluated. RESULTS: There were no significant differences between the two groups in rotation angle and AP translation at each flexion angle. Examining the varus-valgus angle, the NRG group showed varus position at an early flexion angle during both stair activities.Post-cam engagement was observed in both groups during both stair activities. The mean flexion angle of engagement in the NRG group, the post of which was located anterior to the Triathlon, was larger than that in the Triathlon group during both stair activities. CONCLUSION: Despite the same AP single-radius TKA, ML single-radius might affect varus motion at an early flexion angle.

The Association of Stair Climbing Behaviors With Hazard of All-Cause Mortality in Adults With or At Risk of Knee Osteoarthritis.

OBJECTIVE: To investigate the association of stair climbing difficulty and stair climbing frequency with the risk of all-cause mortality over 13 years in adults with or at high risk for knee OA. METHODS: We used data from the Osteoarthritis Initiative (OAI), a prospective cohort study of community-dwelling adults with or at high risk for symptomatic knee OA. The exposures were stair climbing difficulty and frequency, assessed at baseline using self-report questionnaires. The outcome was all-cause mortality, assessed from baseline through 13 years of follow-up. Kaplan-Meier survival curves and Cox proportional hazards regression were used to investigate the association between stair climbing exposures and all-cause mortality. RESULTS: Three hundred seven (6.81%) and 310 (6.84%) participants in the difficulty and frequency samples, respectively, died during 13 years of follow-up. Those who were limited in any capacity in terms of their stair climbing ability had 54% to 84% greater hazard of all-cause mortality, and those who climbed at least 7 flights of stairs per week had 38% lower hazard of all-cause mortality. CONCLUSION: Adults with or at high risk for knee OA who report difficulty with climbing stairs or who infrequently use stairs are at greater hazard of all-cause mortality. Stair climbing difficulty and frequency are simple to collect and changes may occur early in OA progression, allowing for early intervention. Brief questions about stair climbing behaviors can serve as a functional vital sign within the clinician's toolbox.

Evaluating the impact of a short bout of stair-climbing on creative thinking in a between-subjects pretest posttest comparison study.

Recent studies have indicated potential links between short bouts of physical activity like stair-climbing and enhanced creative thinking. However, previous research featured limitations, such as using an uncommon 3 flights round-trip design and lacking baseline creative thinking evaluations. To rectify these limitations and build a more comprehensive understanding, the present study adopts a between-subjects pretest posttest comparison design to scrutinize the effects of ascending stair-climbing on both divergent and convergent thinking. 52 subjects underwent a pretest, followed by random assignment to one of four interventions: ascending stair-climbing for 2, 5, or 8 flights, or taking an elevator for 8 flights, before progressing to a posttest. The results revealed a notable improvement in convergent thinking, measured by the increased number of solved matchstick arithmetic problems (d = 1.165), for participants who climbed 2 flights of stairs compared to those who took the elevator. However, climbing 5 or 8 flights showed no such impact on convergent thinking, and stair-climbing, regardless of the number of flights, did not influence divergent thinking. These findings underscore the utility of brief stair-climbing as an accessible means to enhance convergent thinking in everyday settings, providing a nuanced insight into the relationship between physical activity and creative thinking processes.

Stair climbing and the incidence of atherosclerotic cardiovascular disease: a population-based prospective cohort study.

BACKGROUND: Stair climbing is a readily available form of physical activity with potential cardioprotective merits. Herein, we investigated the association between stair climbing and atherosclerotic cardiovascular disease (ASCVD) incidence among Japanese people. METHODS: This prospective cohort study used data from 7,282 participants, aged 30-84 years, registered in the Suita Study and free from stroke and ischemic heart disease (IHD). Standard approaches were used to detect incident ASCVD events, including cerebral infarction and IHD, during follow-up. Stair climbing was assessed using a baseline questionnaire. We applied the Cox regression to calculate the hazard ratios (HRs) and 95% confidence intervals (95% CIs) of incident ASCVD for climbing stairs in 20-39%, 40-59%, and ≥60% compared to <20% of the time. We adjusted the regression models for age, sex, body mass index, smoking, alcohol consumption, physical activity, hypertension, diabetes, atrial fibrillation, lipid profile, chronic kidney disease, and history of cardiac murmur or valvular diseases. RESULTS: A total of 536 new ASCVD events were detected within a median follow-up period of 16.6 years. In the age- and sex-adjusted model, stair climbing 20-39%, 40-59%, and ≥60% of the time was associated with lower ASCVD incidence: HRs (95% CIs) = 0.72 (0.56, 0.92), 0.86 (0.68, 1.08), and 0.78 (0.61, 0.99), respectively (p-trend = 0.020). The corresponding associations were attenuated after adjusting for lifestyle and clinical factors: HRs (95% CIs) = 0.74 (0.58, 0.95), 0.90 (0.71, 1.13), and 0.89 (0.69, 1.13), respectively (p-trend = 0.152). CONCLUSION: Frequent stair climbing was associated with lower ASCVD incidence; however, this association was partly explained by lifestyle and clinical factors of participants.

Biomechanical effects of an articulating prosthetic toe joint during stair navigation for individuals with unilateral, below-knee limb loss.

Stair navigation is an essential and demanding form of locomotion. During stair ascent and descent, persons with lower limb loss exhibit gait characteristics which may increase their risk of falls and joint degeneration of the intact limb. To reduce deviations from typically-able-bodied gait and overloading of the intact limb for this population, one potential intervention involves modifying passive prosthetic feet by incorporating a flexible toe joint that simulates the biological metatarsophalangeal joint. In this study, we aimed to assess the user preferences and biomechanical effects of a flexible prosthetic toe joint during stair ascent and descent for persons with unilateral lower-limb loss. Nine participants with unilateral lower-limb loss were recruited (Male; Medicare Functional Classification Level: eight K4, one K3; age: 41 ± 11 years; mass: 95 ± 13 kg; height: 1.84 ± 0.05 m; mean ± SD). No significant changes in lower-limb joint mechanics were identified. Five of nine participants preferred the unmodified prosthesis with a standard carbon fiber keel for both stair ascent and descent. Varied user preferences and inconsistent changes in lower-limb joint parameters between participants highlight the importance of subject-specific analyses and individualized device prescription.

Daily stair climbing, disease susceptibility, and risk of atherosclerotic cardiovascular disease: A prospective cohort study.

BACKGROUND AND AIMS: The associations between intensity of stair climbing and atherosclerotic cardiovascular disease (ASCVD) and how these vary by underlying disease susceptibility are not fully understood. We aim to evaluate the intensity of stair climbing and risk of ASCVD types and whether these vary with the presence of ASCVD risk factors. METHODS: This prospective study used data of 458,860 adult participants from the UK Biobank. Information about stair climbing, sociodemographic, and lifestyle factors was collected at baseline and a resurvey 5 years after baseline. ASCVD was defined as coronary artery disease (CAD), ischemic stroke (IS), or acute complications. Associations between flights of stair climbing and ASCVD were examined as hazard ratios (HRs) from Cox proportional hazards models. The modification role of disease susceptibility on such associations was assessed by analyses stratified by levels of genetic risk score (GRS), 10-year risks of ASCVD, and self-reported family history of ASCVD. RESULTS: During a median of 12.5 years of follow-up, 39,043 ASCVD, 30,718 CAD, and 10,521 IS cases were recorded. Compared with the reference group (reported climbing stairs 0 times/day at baseline), the multivariable-adjusted HRs for ASCVD were 0.97 (95% CI, 0.93-1.01), 0.84 (0.82-0.87), 0.78 (0.75-0.81), 0.77 (0.73-0.80) and 0.81 (0.77-0.85) for stair climbing of 1-5, 6-10, 11-15, 16-20 and ≥21 times/day, respectively. Comparable results were obtained for CAD and IS. When stratified by different disease susceptibility based on the GRS for CAD/IS, 10-year risk, and family history of ASCVD, the protection association of stair climbing was attenuated by increasing levels of disease susceptibility. Furthermore, compared with people who reported no stair climbing (<5 times/d) at two examinations, those who climbed stairs at baseline and then stopped at resurvey experienced a 32% higher risk of ASCVD (HR 1.32, 95% CI:1.06-1.65). CONCLUSIONS: Climbing more than five flights of stairs (approx 50 steps) daily was associated with a lower risk of ASCVD types independent of disease susceptibility. Participants who stopped stair climbing between baseline and resurvey had a higher risk of ASCVD compared with those who never climbed stairs.

Risky behavior during stair descent for young adults: Differences in men versus women.

Injuries commonly occur on stairs, with high injury rates in young adults, especially young women. High injury rates could result from physiological and/or behavioral differences; this study focuses on behaviors. The purposes of this observational study were (1) to quantify young adult behaviors during stair descent and (2) to identify differences in stair descent behavior for young adult men versus women. Young adult pedestrians (N = 2,400, 1,470 men and 930 women) were videotaped during descent of two indoor campus staircases, a short staircase (2 steps) and a long staircase (17 steps). Behaviors during stair descent were coded by experimenters. Risky behaviors observed on the short staircase included: No one used the handrail, 16.1% used an electronic device, and 16.4% had in-person conversations. On the long staircase: 64.8% of pedestrians did not use the handrail, 11.9% used an electronic device, and 14.5% had in-person conversations. Risky behaviors observed more in women included: less likely to use the handrail (long staircase), more likely to carry an item in their hands (both staircases), more likely to engage in conversation (both staircases), and more likely to wear sandals or heels (both staircases) (p≤0.05). Protective behaviors observed more in women included: less likely to skip steps (both staircases), and more likely to look at treads during transition steps (long staircase) (p≤0.05). The number of co-occurring risky behaviors was higher in women: 1.9 vs 2.3, for men vs women, respectively (p<0.001). Five pedestrians lost balance but did not fall; four of these pedestrians lost balance on the top step and all five had their gaze diverted from the steps at the time balance was lost. The observed behaviors may be related to the high injury rate of stair-related falls in young adults, and young women specifically.

Relationship between stair ascent gait speed, bone density and gait characteristics of postmenopausal women.

Stair ascent is a biomechanically challenging task for older women. Bone health may affect gait stability during stair walking. This study investigated the gait biomechanics associated with stair ascent in a group of postmenopausal women in relation to walking speed and bone health, quantified by T-score. Forty-five healthy women (mean (SD) age: 67 (14) years), with bone density ranging from healthy to osteoporotic (T-score range +1 to -3), ascended a custom-made five-step staircase with two embedded force plates, surrounded by 10 motion capture cameras, at their self-selected speed. Multivariate regression analyses investigated the explained variance in gait parameters in relation to stair ascent speed and T-score of each individual. Stair ascent speed was 0.65 (0.1) m·s-1 and explained the variance (R2 = 9 to 47%, P ≤ 0.05) in most gait parameters. T-score explained additional variance in stride width (R2 = 20%, P = 0.014), pelvic hike (R2 = 19%, P = 0.011), pelvic drop (R2 = 21%, P = 0.007) and hip adduction (R2 = 7%, P = 0.054). Increased stride width, and thereby a wider base of support, accompanied by increased frontal plane hip kinematics, could be important strategies to improve dynamic stability during stair ascent among this group of women. These findings suggest that targeted exercises of the hip abductors and adductors, including core trunk musculature, could improve dynamic stability during more challenging locomotor tasks. Balance exercises that challenge base of support could also benefit older women with low bone mineral density who may be at risk of falls.

Oxygen uptake efficiency slope in community-dwelling ambulant stroke survivors during walking and stair climbing: a cross-sectional study.

BACKGROUND: Oxygen uptake efficiency slope during submaximal tests has been proposed as a more appropriate measure of aerobic capacity after suffering a stroke, since some individuals cannot tolerate maximal exercise testing. However, it has not yet been investigated whether the oxygen uptake efficiency slope is able to differentiate between healthy individuals and those who have suffered a stroke. OBJECTIVES: To compare the oxygen uptake efficiency slope during walking and stair climbing between stroke survivors and age- and sex-matched healthy controls. METHODS: This is a cross-sectional study in which 18 individuals who had suffered a stroke (stroke survivors) and 18 healthy controls matched for sex and age were included. Oxygen consumption and minute ventilation were collected breath-by-breath during walking (6-min Walk Test) and stair climbing. The oxygen uptake efficiency slope was estimated by the slope of the line obtained through linear regression. RESULTS: The stroke survivors had a lower oxygen uptake efficiency slope during the 6-min Walk Test than the healthy controls (MD 498, 95% CI 122 to 873, p = .01). The between-group difference for the Stair Test was smaller and not statistically significant (MD 349, 95%CI -73 to 772, p = .10). CONCLUSIONS: Stroke survivors had lower oxygen uptake efficiency slope during the performance of the 6-min Walk Test when compared to sex- and age-matched healthy controls. This suggests that stroke survivors have worse cardiopulmonary capacity.

Identification of Early Knee Osteoarthritis Based on Knee Joint Trajectory during Stair Climbing.

Patients with knee osteoarthritis show low stair climbing ability, but a diagnosis of stair performance time is not enough to identify the early stages of knee osteoarthritis. Therefore, we developed an indicator named range of the knee joint trajectory (RKJT) as a kinematic parameter to express more detailed characteristics than stair performance time. To achieve this, we used our developed "IR-Locomotion", a markerless measurement system that can track the knee joint trajectory when climbing stairs. This study aimed to test whether the RKJT effectively identifies patients with early knee osteoarthritis even after controlling stair performance time. Forty-seven adults with moderate to severe knee pain (mean age 59.2 years; 68.1% women) underwent the radiographic examination (Kellgren and Lawrence grade) of both knees and a stair climbing test on 11 stairs. The RKJT during the stair climbing test was calculated by "IR-Locomotion". A generalized linear mixed model was used to evaluate the discriminative capability of RKJT on early knee osteoarthritis (i.e., Kellgren and Lawrence grade of 1). As expected, patients with early knee osteoarthritis showed larger RKJT than non-radiographic controls (95% confidence interval: 1.007, 1.076). Notably, this finding was consistent even after adjusting stair performance time.

Desk based prompts to replace workplace sitting with stair climbing; a pilot study of acceptability, effects on behaviour and disease risk factors.

BACKGROUND: Prolonged sitting is associated with increased risk of obesity, type 2 diabetes and cardiovascular disease. Occupational sitting accounts for up to 50 h/week for employees. This pilot study assessed the acceptability of stair climbing as an interruption to sitting throughout working hours, and provided preliminary data of the effects on glucose and lipid profiles. METHODS: A quasi-experimental design was conducted involving 16 sedentary office workers (five females and 11 males) for intervention (n = 8) and control groups (n = 8) with mean age of 36.38 (5.58). For the eight-week intervention, a continuous four-floor stair climb and descent was performed eight times/day spread evenly over the working day. A prompt to climb was presented on the participant's computer eight times/day. Participants in the experimental group recorded daily floors climbed and steps (measured using pedometers) in a weekly log sheet. Blood samples were collected pre and post intervention to test effects on fasting glucose and 2 h plasma glucose, triglycerides, and total (TC), LDL and HDL cholesterol. Experimental participants were interviewed at the end of the study. The Wilcoxon signed rank test was used to compare the median changes (pre-post) of the dependent variables. RESULTS: On average, the experimental group climbed 121 floors/week when prompted. There were significant reductions in fasting blood glucose, TC and LDL, as well as the derived measures of 'bad' cholesterol and the TC/HDL ratio in the experimental group. Post-experimental interviews indicated that the interruption to sitting was well tolerated. CONCLUSION: Prompted stair climbing activity had impacts on health outcomes and was found acceptable to employees at work. TRIAL REGISTRATION: Ethics for this study was approved by Science, Technology, Engineering and Mathematics Ethical Review Committee, University of Birmingham with ethics reference number ERN_15_0491.

The Predictive Value of Stair Climbing Test on Postoperative Complications in Lung Cancer Patients with Limited Pulmonary Function.

PURPOSE: To evaluate the predictive value of stair climbing test (SCT) on postoperative complications in lung cancer patients with limited pulmonary function. METHODS: A total of 727 hospitalized lung cancer patients with limited pulmonary function were retrospectively reviewed. Included in the cohort were 424 patients who underwent SCT preoperatively. Patients were grouped according to general condition, past medical history, surgical approach, pulmonary function test, and SCT results. Comparison of the postoperative cardiopulmonary complication rates was made and independent risk factors were identified. RESULTS: A total of 89 cardiopulmonary-related complications occurred in 69 cases, accounting for 16.3% of the entire cohort. The postoperative cardiopulmonary complication rates were significantly different between groups stratified by smoking index, percentage of forced expiratory volume in one second, percentage of diffusion capacity for carbon monoxide, SCT results, excision extension, and anesthetic duration (p <0.05). Multivariate analysis showed that only height achieved (p <0.001), changes in heart rate (∆HR; p <0.001), and excision extension (p = 0.006) were independent risk factors for postoperative cardiopulmonary complications. CONCLUSIONS: The SCT could be used as a preoperative screening method for lung cancer patients with limited pulmonary function. For those patients who could only climb less than 6 floors or had ∆HR >30 bpm in the test, sublobar resection should be selected to reduce the postoperative cardiopulmonary complication rate.

Evaluación de la respuesta aguda sobre distintas variables mecánicas, fisiológicas y metabólicas tras un ejercicio de subida de escaleras con equipo específico en bomberos profesionales / Avaliação da resposta aguda em diferentes variáveis mecânicas, fisiológicas e metabólicas após um exercíciode subida de escada com equipamentos específicos em bombeiros profissionais / Evaluation of the acute response on different mechanical, physiological and metabolic variables after a stair- climbing exercise with specific gear in professional firefighters

Objetivo: Analizar las respuestas agudas de una prueba de subida de escaleras con equipo especifico sobre distintas variables mecánicas, metabólicas yfisiológicas en un grupo de bomberos profesionales. Método: 34 bomberos (Edad: 42.7 ± 8.2 años; Peso: 76.16 ± 6.70 kg; Estatura: 177 ± 5 cm) realizaron una prueba de subida de una escalera de seisplantas con equipo específico a la máxima velocidad. Antes y después de dicha prueba, se evaluó su capacidad de salto vertical (CMJ) y la fuerza muscularde las piernas en el ejercicio de sentadilla completa con una carga similar a la carga del equipo específico (35 kg, VMP35kg); se analizaron tambiéndiferentes variables fisiológicas (saturación de oxígeno [O2] y frecuencia cardiaca [FC]) y metabólicas (lactato en sangre [La]). Los participantes seagruparon en 3 rangos de edad (G1: 26-35 años; G2: 36-45 años; G3: ≥ 46 años).Resultados: Se observó una pérdida significativa (p < 0.001) en la capacidad de salto CMJ y en la VMP35kg tras la prueba de subida de escaleras, junto conun aumento significativo (p < 0.001) en [La] y en la FC. Entre grupos de edad, se hallaron diferencias significativas (p < 0.05) en el salto CMJ y en la VMPde la sentadilla con 35 kg en los G1 y G2 con respecto al G3, siempre a favor de los grupos de menos edad.Conclusiones:El ejercicio de subida de escaleras con el equipo específico produjo una disminución significativa del rendimiento en la fuerza muscular delas piernas, así como un aumento significativo en las variables fisiológicas y metabólicas de FC y La, y una disminución significativa en la saturación de O2,indicando que este tipo de esfuerzo produce una fatiga elevada.(AU)

Objective: To analyse the acute response on different mechanical, physiological and metabolic variables after a stair-climbing exercise with specific gearin professional firefighters.Method: 34 professional firefighters (Age: 42.7 ± 8.2 years; Weight: 76.16 ± 6.70 kg; Heigh: 177 ± 5 cm) performed a stair-climbing exercise over 6 floorswith specific gear at maximum speed. Before and after this exercise, different mechanical variables: vertical jump capacity (CMJ) and lower limb strengthin full squat exercise with a load equivalent to that of the specific gear (35 kg, VMP35kg); and physiological and metabolic variables: oxygen saturation[O2], heart rate [FC] and lactate [La] were analysed. Participants were also grouped by age ranges (G1: 26-35 years; G2: 36-45 years; G3: ≥ 46 years).Results: A significant decrease (p < 0.001) in vertical jump capacity and lower limb strength in full squat after the stair-climbing exercise was observed. Inaddition, a significant increase (p < 0.001) in lactate and heart rate was also observed. When analysing by age ranges, significant differences (p < 0.05) invertical jump and squat exercise with 35kg were observed in G1 and G2 with respect to G3, always in favor of the younger age group. Conclusions: The stair-climbing exercise with specific gear showed a significant decrease in lower limb strength performance, as well as a significantincrease in heart rate and lactate variables, and a significant decrease in oxygen saturation. These results indicate that this type of effort induces highlevels of fatigue.(AU)

Objetivo: Analisar as respostas agudas de um teste de subida de escada com equipamento específico sobre diferentes variáveis mecânicas, metabólicas efisiológicas em um grupo de bombeiros profissionais.Método: 34 bombeiros (Idade: 42.7 ± 8.2 anos; Peso: 76.16 ± 6.70 kg; Altura: 177 ± 5 cm) realizaram um teste de subida de escada de seis andares comequipamento específico em velocidade máxima. Antes e após tal teste, foram avaliadas a capacidade de salto vertical (CMJ) e força muscular da perna noexercício de agachamento completo com carga semelhante à carga do equipamento específico (35kg, VMP35kg); Diferentes variáveis fisiológicas(saturação de oxigênio [O2] e frequência cardíaca [FC]) e metabólicas (lactato sanguíneo [La]) também foram analisadas. Os participantes foramagrupados em 3 faixas etárias (G1: 26-35 anos; G2: 36-45 anos; G3: ≥ 46 anos).Resultados: Foi observada uma perda significativa (p < 0,001) na capacidade de salto do CMJ e VMP35kg após o teste de subir escadas, juntamente comum aumento significativo (p < 0,001) na [La] e na FC. Entre as faixas etárias, foram encontradas diferenças significativas (p < 0,05) no salto CMJ e noagachamento VMP de 35kg no G1 e G2 em relação ao G3, sempre a favor das faixas etárias mais jovensConclusões: O exercício de subir escadas com o equipamento específico produziu uma diminuição significativa do desempenho na força muscular daspernas, assim como um aumento significativo nas variáveis fisiológicas e metabólicas de FC e La, e uma diminuição significativa na saturação de O2,indicando que este tipo de esforço produz alta fadiga.(AU)

Cardiovascular responses to high-intensity stair climbing in individuals with coronary artery disease.

Exercise-based cardiac rehabilitation leads to improvements in cardiovascular function in individuals with coronary artery disease. The cardiac effects of coronary artery disease (CAD) can be quantified using clinical echocardiographic measures, such as ejection fraction (EF). Measures of cardiovascular function typically only used in research settings can provide additional information and maybe more sensitive indices to assess changes after exercise-based cardiac rehabilitation. These additional measures include endothelial function (measured by flow-mediated dilation), left ventricular twist, myocardial performance index, and global longitudinal strain. To investigate the cardiovascular response to 12 week of either traditional moderate-intensity (TRAD) or stair climbing-based high-intensity interval (STAIR) exercise-based cardiac rehabilitation using both clinical and additional measures of cardiovascular function in individuals with CAD. Measurements were made at baseline (BL) and after supervised (4wk) and unsupervised (12 week) of training. This study was registered as a clinical trial at clinicaltrials.gov (NCT03235674). Participants were randomized into either TRAD (n = 9, 8M/1F) and STAIR (n = 9, 8M/1F). There was a training-associated increase in one component of left ventricular twist: Cardiac apical rotation (TRAD: BL: 5.6 ± 3.3º, 4 week: 8.0 ± 3.9º, 12 week: 6.2 ± 5.1º and STAIR: BL: 5.1 ± 3.6º, 4 week: 7.4 ± 3.9º, 12 week: 7.8 ± 2.8º, p (time) = 0.03, η2  = 0.20; main effect) and post-hoc analysis revealed a difference between BL and 4 week (p = 0.02). There were no changes in any other clinical or additional measures of cardiovascular function. The small increase in cardiac apical rotation observed after 4 weeks of training may indicate an early change in cardiac function. A larger overall training stimulus may be needed to elicit other cardiovascular function changes.

Gait Phase Subdivision and Leg Stiffness Estimation During Stair Climbing.

Leg stiffness is considered a prevalent parameter used in data analysis of leg locomotion during different gaits, such as walking, running, and hopping. Quantification of the change in support leg stiffness during stair ascent and descent will enhance our understanding of complex stair climbing gait dynamics. The purpose of this study is to investigate a methodology to estimate leg stiffness during stair climbing and subdivide the stair climbing gait cycle. Leg stiffness was determined as the ratio of changes in ground reaction force in the direction of the support leg Fl (leg force) to the respective changes in length Ll during the entire stance phase. Eight subjects ascended and descended an instrumented staircase at different cadences. In this study, the changes of leg force and length (force-length curve) are described as the leg stiffness curve, the slope of which represents the normalized stiffness during stair climbing. The stair ascent and descent gait cycles were subdivided based on the negative and positive work fluctuations of the center-of-mass (CoM) work rate curve and the characteristics of leg stiffness. We found that the leg stiffness curve consists of several segments in which the force-length relationship was similarly linear and the stiffness value was relatively constant; the phase divided by the leg stiffness curve corresponds to the phase divided by the CoM work rate curve. The results of this study may guide biomimetic control strategies for a wearable lower-extremity robot for the entire stance phase during stair climbing.

Stair climbing and incident atrial fibrillation: a prospective cohort study.

BACKGROUND: A protective role for physical activity against the development of atrial fibrillation (AF) has been suggested. Stair climbing is a readily available form of physical activity that many people practice. Herein, we investigated the association between stair climbing and the risk of AF in a Japanese population. METHODS: In this prospective cohort study, we used data of 6,575 people registered in the Suita Study, aged 30-84 years, and had no history of AF. The frequency of stair climbing was assessed by a baseline questionnaire, while AF was diagnosed during the follow-up using a 12-lead ECG, health records, check-ups, and death certificates. We used the Cox regression to calculate the hazard ratios and 95% confidence intervals of AF incidence for climbing stairs in 20-39%, 40-59%, and ≥60% compared with <20% of the time. RESULTS: Within 91,389 person-years of follow-up, 295 participants developed AF. The incidence of AF was distributed across the stair climbing groups <20%, 20-39%, 40-59%, and ≥60% as follows: 3.57, 3.27, 3.46, and 2.63/1,000 person-years, respectively. Stair climbing ≥60% of the time was associated with a reduced risk of AF after adjustment for age and sex 0.69 (0.49, 0.96). Further adjustment for lifestyle and medical history did not affect the results 0.69 (0.49, 0.98). CONCLUSION: Frequent stair climbing could protect from AF. From a preventive point of view, stair climbing could be a simple way to reduce AF risk at the population level.

Interrupting Pedestrians in Indonesia; Effect of Climate on Perceived Steepness and Stair Climbing Behaviour.

Increased activity during daily life is one public health initiative to reduce population inactivity. Increasing temperature and humidity influence walking for transport by reducing the blood supply available to exercising muscles. This study investigated effects of temperature and humidity on a perceptual cue, estimated stair slant, that can influence behaviour, and on subsequent speed of climbing. Participants (402 males, 423 females) estimated the slant of a 20.4° staircase at a university in Indonesia. Subsequently, the participants were timed covertly while climbing. As temperature and humidity increased, estimated stair slant became more exaggerated. Females estimated stair slant as steeper than males. For stair climbing, speed was reduced as temperature increased, and females climbed slower than males. Estimates of stair slant were not associated with speed of the subsequent climb. Climate influences estimates of stair slant that precede stair climbing and subsequent speed of the ascent. In this study, perception was unrelated to behaviour.

Association Between Knee Moments During Stair Navigation and Participant-Related Factors in Individuals With Anterior Cruciate Ligament Reconstruction: A Cross-Sectional Study.

CONTEXT: Altered knee joint mechanics may be related to quadriceps muscle strength, time since surgery, and sex following anterior cruciate ligament reconstruction (ACLR). The aim of this study was to investigate the association between knee moments, with participant-related factors during stair navigation post-ACLR. DESIGN: Cross-sectional study. METHODS: A total of 30 participants (14 women) with ACLR, on average 7.0 (SD 4.4) years postsurgery were tested during stair ascent and descent in a gait laboratory. Motion capture was conducted using a floor-embedded force plate and 11 infrared cameras. Quadriceps concentric and eccentric muscle strength was measured with an isokinetic dynamometer at 60°/s, and peak torques recorded. Multiple regression analyses were performed between external knee flexion and adduction moments, respectively, and quadriceps peak torque, sex, and time since ACLR. RESULTS: Higher concentric quadriceps strength and female sex accounted for 55.7% of the total variance for peak knee flexion moment during stair ascent (P < .001). None of the independent variables accounted for variance in knee adduction moment (P = .698). No significant associations were found for knee flexion and adduction moments during for stair descent. CONCLUSION: Higher quadriceps concentric strength and sex explains major variance in knee flexion moments during stair ascent. The strong association between muscle strength and external knee flexion moments during stair ascent indicate rehabilitation tailored for quadriceps may optimize knee mechanics, particularly for women.

Biomechanical compensation mechanisms during stair climbing - The effect of leg length inequalities.

BACKGROUND: Stair climbing is a complex and demanding daily activity with increased physical loads. Therefore, analyzing stair climbing abilities is a frequently used diagnostic tool. Leg length inequalities (LLIs) are a common condition in the population, with individual consequences like lower back pain, scoliosis, and osteoarthritis. Despite its high prevalence, the necessary treatment, for mild LLIs, is still controversial. Previously, the focus was to analyze the effects of LLIs during static standing and walking. To create a holistic view on the dynamic effects of LLIs, and since climbing stairs produces a similar biomechanical imbalance as LLIs, the compensation mechanics during stair climbing are of special interest. RESEARCH QUESTION: What are the biomechanical compensation mechanisms of (simulated) LLIs during ascending and descending stairs? METHODS: Thirty-five healthy participants were measured with the inertial measurement system MyoMotion during stair climbing with simulated LLIs of 0-3 cm. The maximum estimated lower limb joint angles of the long and short leg were analyzed with statistically repeated measurement models. RESULTS: The long leg showed significantly increased hip and knee flexion, while the short leg showed decreased hip and knee flexion, decreased dorsiflexion, and significantly increased plantarflexion. Different mechanisms were found in the case of 1 cm LLI when compared to greater LLIs. In the former, increased hip and knee flexion in the short leg accompanied by increased dorsiflexion in the long leg was observed. In the latter, the dorsiflexion of the long leg was reduced. SIGNIFICANCE: Except for the reduced dorsiflexion of the long leg (LLI >1 cm), during stair climbing compared compensation mechanisms as during walking were presented, with the long leg functionally shortened and the short leg lengthened. Although the feet were already on different levels, during stair climbing with the step-over-step technique, significant compensation mechanisms were found as a consequence of LLIs.