Everyday tasks impair spatiotemporal variables of gait in older adults with Parkinson's disease

IntroductionAlthough it is known that individuals with Parkinson's disease (PD) have difficulties performing dual-task activities, most of the studies have verified the effect of dual tasks on gait using tasks that are uncommon to perform while walking. However, the realization of tasks involving gait that really represents the daily activities carried out by the participants, allow us to detect real fall risk situations of individuals with PD during their gait.ObjectiveOur aim was to verify the influence of daily-life dual-tasks on gait spatiotemporal variables of the older adults with PD.Methods20 older adults without PD and 20 older adults with PD participated in the study. Gait kinematic was analyzed under three different conditions: walking without dual task, walking carrying bags with weight, and walking talking on the cell phone.ResultsOlder adults with PD presented lower speed (p = .001), cadence (p = .039), and shorter step length (p = .028) than older adults without PD during walking without dual tasks. When walking while carrying bags with weight, older adults with PD had a lower speed (p < .001), cadence (p = .015), shorter step length (p = .008), and greater double support time (p = .021) compared with older adults without PD. During walking while talking on the cell phone, older adults with PD walked with lower speed (p < .001), cadence (p = .013), shorter step length (p = .001) and swing time (p = .013), and increased double support time (p = .008) and support time (p = .014) in relation to older adults without PD.ConclusionDaily-life dual tasks impair the spatiotemporal variables of gait in the older adults with PD, which was most evident during walking talking on the cell phone.     

Effect of different residential settings on gait kinematic parameters in older adults with cognitive impairment

ObjectiveTo compare the parameters of gait kinematics of older adults with cognitive impairment who live in community dwellings or those living or spending most of the time in non-family environment settings.MethodsThe sample was composed of 33 older adults of both sexes with cognitive impairment. Participants were separated into three groups: a community-dwelling older adult group comprised of 11 subjects; a semi-institutionalized older adult group comprised of 10 older adults attended in a geriatric daycare institution; and an institutionalized older adult group comprised of 12 older adults living in long-term institutions. Gait kinematics were recorded by pressure sensors (footswitches). Fifty gait cycles at self-selected pace were analyzed to obtain: gait speed, stride length, stance, swing, and stride time. The variability of these parameters was also analyzed.ResultsMANCOVA identified the main effect of groups (p < 0.001). Gait speed of older adults living in long-term institutions and older adults attended in geriatric daycare institutions was slower than community-living older adults (p < 0.001 and p = 0.04, respectively). Swing and stride time variability was higher in older adults living in long-term institutions (p = 0.003 and p = 0.001) and in older adults attended in geriatric daycare institutions (p = 0.02 and p = 0.001) than in community-dwelling older adults.ConclusionThe most important finding was that older adults with cognitive impairment who need non-family residential setting care had higher gait kinematics abnormalities, which may increase the risk of falls, compared to those who live in the community.     

Age and walking conditions differently affect domains of gait

IntroductionAnalysing gait in controlled conditions that resemble daily life walking could overcome the limitations associated with gait analysis in uncontrolled real-world conditions. Such analyses could potentially aid the identification of a walking condition that magnifies age-differences in gait. Therefore, the aim of the current study was to determine the effects of age and walking conditions on gait performance.MethodsTrunk accelerations of young (n = 27, age: 21.6) and older adults (n = 26, age: 68.9) were recorded for 3 min in four conditions: walking up and down a university hallway on a track of 10 m; walking on a specified path, including turns, in a university hallway; walking outside on a specified path on a pavement including turns; and walking on a treadmill. Factor analysis was used to reduce 27 computed gait measures to five independent gait domains. A multivariate analysis of variance was used to examine the effects of age and walking condition on these gait domains.ResultsFactor analysis yielded 5 gait domains: variability, pace, stability, time & frequency, complexity, explaining 64% of the variance in 27 gait outcomes. Walking conditions affected all gait domains (p < 0.01) but age only affected the time & frequency domain (p < 0.05). Age and walking conditions differently affected the domains variability, stability, time & frequency. The largest age-differences occurred mainly during straight walking in a hallway (variability: 31% higher in older adults), or during treadmill walking (stability: 224% higher, time&frequency: 120% lower in older adults).ConclusionWalking conditions affect all domains of gait independent of age. Treadmill walking and walking on a straight path in a hallway, were the most constrained walking conditions in terms of limited possibilities to adjust step characteristics. The age by condition interaction suggests that for the gait domains variability, stability, and time & frequency, the most constrained walking conditions seem to magnify the age-differences in gait.     

Repeated exposure to tripping like perturbations elicits more precise control and lower toe clearance of the swinging foot during steady walking

Controlling minimum toe clearance (MTC) is considered an important factor in preventing tripping. In the current study, we investigated modifications of neuro-muscular control underlying toe clearance during steady locomotion induced by repeated exposure to tripping-like perturbations of the right swing foot. Fourteen healthy young adults (mean age 26.4 ± 3.1 years) participated in the study. The experimental protocol consisted of three identical trials, each involving three phases: steady walking (baseline), perturbation, and steady walking (post-perturbation). During the perturbation, participants experienced 30 tripping-like perturbations at unexpected timing delivered by a custom-made mechatronic perturbation device. The temporal parameters (cadence and stance phase_%), mean, and standard deviation of MTC were computed across approximately 90 strides collected during both baseline and post-perturbation phases, for all trials. The effects of trial (three levels), phase (two levels: baseline and post-perturbation) and foot (two levels: right and left) on the outcome variables were analyzed using a three-way repeated measures analysis of variance. The results revealed that exposure to repeated trip-like perturbations modified MTC toward more precise control and lower toe clearance of the swinging foot, which appeared to reflect both the expectation of potential forthcoming perturbations and a quicker compensatory response in cases of a lack of balance. Moreover, locomotion control enabled subjects to maintain symmetric rhythmic features during post-perturbation steady walking. Finally, the effects of exposure to perturbation quickly disappeared among consecutive trials.     

Gait training facilitates push-off and improves gait symmetry in children with cerebral palsy

BackgroundHuman walking involves a rapid and powerful contraction of ankle plantar flexors during push-off in late stance.ObjectiveHere we investigated whether impaired push-off force contributes to gait problems in children with cerebral palsy (CP) and whether it may be improved by intensive gait training.MethodsSixteen children with CP (6–15 years) and fourteen typically developing (TD) children (4–15 years) were recruited. Foot pressure was measured by insoles and gait kinematics were recorded by 3-dimensional video analysis during treadmill and overground walking. The peak derivative of ground reaction force at push off (dPF) was calculated from the foot pressure measurements. Maximal voluntary plantar flexion (MVC) was measured while seated. Measurements were performed before and after a control period and after 4 weeks of 30 minutes daily inclined treadmill training.ResultsdPF and MVC were significantly lower in children with CP on the most affected (MA) as compared to TD children (p < .001). dPF was lower on the MA leg as compared to the less affected (LA) leg in children with CP (p < .05). Following gait training, increases in dPF (p < .001) and MVC (p < .01) were observed for the MA leg. Following gait training children with CP showed similar timing of dPF and similar stance phase duration on both legs indicating improved symmetry of gait. These effects were also shown during overground walking.ConclusionImpaired ability to voluntarily activate ankle plantar flexors and produce a rapid and powerful push-off during late stance are of importance for impaired gait function in children with CP. Intensive treadmill training may facilitate the drive to ankle plantar flexors and reduce gait asymmetry during both treadmill and overground walking.     

Sex differences in the impact of state and trait fatigue on gait variability

Conditions requiring greater attention or cognitive control, such as fatigue, lead to changes in the motor performance of a task. Perceived fatigue refers to subjective feelings of fatigue, can be expressed as a state variable or trait characteristic and is influenced by demographic factors, such as sex. The purpose of this study was to determine how sex interacts with state and trait physical fatigue (PF) and mental fatigue (MF) to influence gait variability. METHODS: 123 healthy adults (77 female, 46 male), aged 18–36 years, completed the Mental and Physical State and Trait Energy and Fatigue Scale. Using a median split for each fatigue variable, participants were placed into “low” or “high” fatigue categories. Gait variability was defined as the asymmetry of lateral step variability (ALSV) and coefficient of variation (CV) of gait speed, stride length and double limb (DL) support during overground walking. RESULTS: Males with low state PF had greater ALSV than females with low state PF (p = 0.05, η²_p = 0.07) and males with high state PF (p = 0.007, η²_p = 0.15). Females with high trait MF had greater CV of gait speed than females with low trait mental fatigue (p = 0.02, η²_p = 0.08). Males with low trait MF had greater CV of gait speed (p = 0.01, η²_p = 0.10) and stride length (p = 0.002, η²_p = 0.17) than females with low trait MF. CV of DL support did not vary based on fatigue level or sex (p ≥ 0.11). CONCLUSIONS: There are sex-specific differences in the impact of state PF on asymmetry of lateral step variability and trait MF on the variability of gait speed and stride length.     

Influence of step-surface visual properties on confidence,anxiety, dynamic stability,and gaze behaviour in young and older adults

BackgroundStep-surface visual properties are often associated with stair falls. However, evidence for decorating stairs typically concerns the application of step-edge highlighters rather than the entire step-surface. Here we examine the influence of step-surface visual properties on stair descent safety, with a view to generating preliminary evidence for safe stair décor.MethodsFourteen young (YA: 23.1 ± 3.7 years), 13 higher (HAOA: 67 ± 3.5) and 14 lower (LAOA: 73.4 ± 5.7) ability older adults descended a seven-step staircase. Older adults were stratified based on physiological/cognitive function. Step-surface décor patterns assessed were: Black and white (Busy); fine grey (Plain); and striped multicolour (Striped); each implemented with/without black edge-highlighters (5.5 cm width) totalling six conditions. Participants descended three times per condition. Confidence was assessed prior to, and anxiety following, the first descent in each condition. 3D kinematics (Vicon) quantified descent speed, margin of stability, and foot clearances with respect to step-edges. Eye tracking (Pupil-labs) recorded gaze. Data from three phases of descent (entry, middle, exit) were analysed. Linear mixed-effects models assessed within-subject effects of décor (×3) and edge highlighters (×2), between-subject effects of age (×3), and interactions between terms (α = p < .05).ResultsDécor: Plain décor reduced anxiety in all ages and abilities (p = .032, effect size: g_av = 0.3), and increased foot clearances in YA and HAOA in the middle phase (p < .001, g_av = 0.53), thus improving safety. In contrast, LAOA exhibited no change in foot clearance with Plain décor. Patterned décor slowed descent (Busy: p < .001, g_av = 0.2), increased margins of stability (Busy: p < .001, g_av = 0.41; Striped: p < .001, gav = 0.25) and reduced steps looked ahead (Busy: p = .053, gav = 0.25; Striped: p = .039, gav = 0.28) in all ages and abilities. This reflects cautious descent, likely due to more challenging conditions for visually extracting information about the spatial characteristics of the steps useful to guide descent.Edge highlighters: Step-edge highlighters increased confidence (p < .001, g_av = 0.53) and reduced anxiety (p < .001, g_av = 0.45) in all ages and abilities and for all décor, whilst removing them slowed descent in HAOA (p = .01, g_av = 0.26) and LAOA (p = .003, g_av = 0.25). Step-edge highlighters also increased foot clearance in YA and HAOA (p = .003, g_av = 0.14), whilst LAOA older adults showed no adaptation. No change in foot clearances with décor or step-edge highlighters in LAOA suggests an inability to adapt to step-surface visual properties.ConclusionPatterned step surfaces can lead to more cautious and demanding stair negotiation from the perspective of visually extracting spatial information about the steps. In contrast, plain décor with step edge highlighters improves safety. We therefore suggest plain décor with edge highlighters is preferable for use on stairs.     

How do skeletal and postural parameters contribute to maintain balance during walking?

IntroductionMaintaining balance during gait allows subjects to minimize energy expenditure and avoid falls. Gait balance can be measured by assessing the relationship between the center of mass (COM) and center of pressure (COP) during gait. Demographics, skeletal and postural parameters are known to influence gait balance.PurposeWhat are the determinants of dynamic balance during gait in asymptomatic adults among skeletal and demographic parameters?Methods115 adults underwent 3D gait analysis and full-body biplanar X-rays. Angles between the COM-COP line and the vertical were calculated in frontal and sagittal planes during gait: maxima, minima, and ROM were evaluated. Full-body 3D reconstructions were obtained; skeletal and postural parameters of the spine (lumbar lordosis, thoracic kyphosis, sagittal vertical axis SVA), pelvis (pelvic tilt and incidence, acetabular orientation in the 3 planes) and lower limbs (neck shaft angle femoral and tibial torsions) were calculated. A univariate followed by a multivariate analysis were computed between the COM-COP parameters and skeletal and demographic parameters.ResultsThe univariate analysis showed that in the frontal plane, maximum (4.6°) of the COM-COP angle was significantly correlated with weight (r = 0.53), age (r = 0.28), height (r = 0.35), SVA (r = 0.23), T1T12 (r = 0.24) and pelvic width (r = 0.25).In the sagittal plane, maximum COM-COP (19.7 ± 2.8°) angle was significantly correlated to acetabular tilt (r = 0.25) and acetabular anteversion (r = 0.21). The multivariate analysis showed that, in the frontal plane, an increase in the maximum of the COM-COP angle was determined by a decreasing height (β = −0.28), an increasing weight (β = 0.48), being a male (β = −0.42), and an increasing posterior acetabular coverage (β = 0.22). In the sagittal plane, an increasing maximum COM-COP angle was determined by a decreasing height (β = −0.38) and an increasing SVA (β = 0.19).ConclusionFrontal imbalance appeared to be mainly correlated to demographic parameters. Sagittal imbalance was found to be correlated with weight, height, acetabular parameters and SVA. These results suggest that in addition to demographic parameters, acetabular parameters and SVA are important determinants of balance during gait.     

A modified surface EMG biomarker for gait assessment in spastic cerebral palsy

ObjectiveMuscle clinical metrics are crucial for spastic cocontraction management in children with Cerebral Palsy (CP). We investigated whether the ankle plantar flexors cocontraction index (CCI) normalized with respect to the bipedal heel rise (BHR) approach provides more robust spastic cocontraction estimates during gait than those obtained through the widely accepted standard maximal isometric plantar flexion (IPF).MethodsTen control and 10 CP children with equinus gait pattern performed the BHR and IPF testing and walked barefoot 10-m distance. We compared agonist medial gastrocnemius EMG during both testing and CCIs obtained as the ratios of antagonist EMG during swing phase of gait and either BHR or IPF agonist EMG.ResultsAgonist EMG values from the BHR were: (i) internally reliable (Cronbach's α = 0.993), (ii) ~50 ± 0.4% larger than IPF, (iii) and positively correlated. Derived CCIs were significantly smaller (p < 0.05) in both populations.ConclusionThe bipedal heel rise approach may be accurate enough to reveal greater agonist activity of plantar flexors than the maximal isometric plantar flexion and seems to be more appropriate to obtain cocontraction estimates during swing of gait.SignificanceThis modified biomarker may represent a step forward towards improved accuracy of spastic gait management in pediatric.     

Increased forefoot loading is associated with an increased plantar flexion moment

The aim of this study was to identify the cascade of effects leading from alterations in force generation around the ankle joint to increased plantar pressures under the forefoot. Gait analysis including plantar pressure measurement was performed at an individually preferred and a standardized, imposed gait velocity in diabetic subjects with polyneuropathy (n = 94), without polyneuropathy (n = 39) and healthy elderly (n = 19). The plantar flexion moment at 40% of the stance phase was negatively correlated with the displacement rate of center of pressure (r = ?.749, p < .001 at the imposed, and r = ?.693, p < .001 at the preferred gait velocity). Displacement rate of center of pressure was strongly correlated with forefoot loading (r = ?.837, p < .001 at the imposed, and r = ?.731, p < .001 at the preferred gait velocity). People with a relatively high plantar flexion moment at 40% of the stance phase, have a faster forward transfer of center of pressure and consequently higher loading of the forefoot. This indicates that interventions aimed at increasing the control of the roll-off of the foot may contribute to a better plantar pressure distribution.     

Evaluating dynamic similarity of fixed,self-selected and anatomically scaled speeds in non-linear analysis of gait during treadmill running

ObjectivesThe aim of this study is to evaluate how speed affects non-linear measures of variability. Fixed and self-selected speeds were compared to an anatomically scaled speed calculated based on leg length to evaluate which provided a more reproducible result between subjects.MethodsSixteen subjects ran on a treadmill at a fixed, scaled and self-selected speed and at ±10% in each case. Kinematic data were collected for two minutes at 250 Hz for each trial. Sample entropy (SaEn) and maximum Lyapunov exponents (LyE) were calculated from the sagittal knee and hip joint angles to evaluate regularity of gait and local stability. These nonlinear measures were compared to evaluate the dynamic similarity of the movement in each case, and to evaluate speed as a confounding variable in non-linear analysis.ResultsAn anatomically scaled speed shows more dynamic similarity than a fixed or self-selected speed with the lowest observed coefficient of variation for each measure. This was found to be statistically significant for both nonlinear measures of the hip (SaEn p = 0.038; LyE p = 0.040). Speed was not found to be a confounding variable in non-linear analysis of running gait of a healthy population (η² < 0.05).ConclusionsChanges in speed by ±10% do not significantly affect stability and variability of gait for healthy participants, suggesting that they make adaptations to ensure optimal gait variability.Anatomically scaled speeds provide a more reliable methodology for both linear and non-linear analysis by providing a definitive protocol, suggesting it could replace self-selected or fixed speeds in future research.     

Biofeedback augmenting lower limb loading alters the underlying temporal structure of gait following anterior cruciate ligament reconstruction

Biofeedback has recently been explored to target deviant lower extremity loading mechanics following anterior cruciate ligament reconstruction (ACLR) to mitigate the development of post traumatic osteoarthritis. The impact this feedback has on the structure of the stride interval dynamics—a barometer of gait system health—however, have yet to be examined. This study was designed to assess how feedback, used to alter lower-extremity loading during gait, affects the structure of stride interval variability by examining long-range stride-to-stride correlations during gait in those with unilateral ACLR. Twelve participants walked under three separate loading conditions: (1) control (i.e., no cue) (2) high loading, and (3) low loading. Baseline vertical ground reaction force (vGRF) data was used to calculate a target 5% change in vGRF for the appropriate loading condition (i.e., high loading was +5% vGRF, low loading was −5% vGRF). The target for the load condition was displayed on a screen along with real-time vGRF values, prescribing changes in stride-to-stride peak vertical ground reaction forces of each limb. From time-series of stride intervals (i.e., duration), we analyzed the mean and standard deviation of stride-to-stride variability and, via detrended fluctuation analysis (i.e., DFA α), temporal persistence for each feedback condition. Both the high and low loading conditions exhibited a change toward more temporally persistent stride intervals (high loading: α =0.92, low loading: α = 0.98) than walking under the control condition (α = 0.78; high vs. control: p = .026, low vs. control: p = .001). Overall, these results indicate that altering lower extremity load changes the temporal persistence of the stride internal dynamics in ACLR individuals, demonstrating the implications of the design of gait training interventions and the influence feedback has on movement strategies.     

Investigating real-time physical activity behavior using ecological momentary assessment: Effects of mental fatigue and benefit-cost valuations

BackgroundCurrent research investigating the relationship between mental fatigue and physical activity behaviors relies on laboratory-based, experimental studies which lack ecological validity.ObjectiveThis study used ecological momentary assessment (EMA) to assess feelings of mental fatigue and subjective evaluations (benefits and costs) as predictors of moderate-to-vigorous intensity physical activity in the everyday lives of young adults.MethodsOne hundred participants (n = 22 males, n = 78 females, M_age = 20.60 years, 70% meeting or exceeding physical activity guidelines) responded to digital survey prompts up to four times a day and wore an accelerometer for seven consecutive days. Moderate-to-vigorous intensity physical activity in the 180-min time window following each survey prompt was recorded. Data from the 28 survey-moderate-to-vigorous intensity physical activity epochs were analyzed using multilevel mixed-effects linear modelling.ResultsHigher levels of mental fatigue than one’s average level were associated with engaging in fewer moderate-to-vigorous intensity physical activity minutes (p = .004) and lower benefit vs. cost scores (p = .001). Higher benefit vs. cost scores than one’s average level were associated with engaging in more minutes of moderate-to-vigorous intensity physical activity (p < .001).ConclusionsResults are the first to demonstrate outside the lab, that mental fatigue experienced in everyday life may amplify the perceived costs of moderate-to-vigorous intensity physical activity, with both factors playing a potential role in moderate-to-vigorous intensity physical activity decision-making. Future research may apply insights gained from this study in design and testing of real-time interventions promoting moderate-to-vigorous intensity physical activity.     

Stressful Life Events and Distress in Breast Cancer: A 5-Years Follow-Up

Background/ObjectiveEnvironmental factors such as psychosocial stress have demonstrated to have an impact on the breast cancer (BC) course. This study aims to explore the impact of psychotherapy and stressful life events (SLE) on BC survivors’ illness trajectories.Method68 women with BC underwent Positive Psychotherapy or Cognitive-Behavioral Stress Management and 37 patients were included as a control group. The effects of distress reduction and SLE on their 5-year recurrence were investigated. Additional analyses examined the effect of receiving vs. not receiving psychotherapy and of the type of therapy on survival and disease-free interval, DFI.ResultsA one-point decrease of the Hospital Anxiety and Depression Scale (HADS) after psychotherapy predicted a lower risk of 5-year recurrence, OR = 0.84, p = .037, 95% CI = 0.71-0.99). Also, a one point-increase in the number threatening SLE (OR = 1.92; p = .028, 95% CI = 1.07-3.43) was related to higher 5-year recurrence.ConclusionsThe findings highlight the necessity of studying not only a given situation (i.e., psychotherapy, SLE) but its specific impact on individuals.     

The mediational role of executive functions for the relationship between motor ability and academic performance in pediatric cancer survivors

IntroductionPediatric Cancer Survivors (PCS) bear a high risk for late effects within motor abilities (MAs) and executive functions (EFs). In typically developing children, these domains are interrelated and predictors of academic performance. The current study investigated (i) whether MAs and EFs are also interrelated in PCS, and (ii) whether EFs mediate the relation between MAs and academic performance.Methods78 PCS (7–16 years; M = 11.23; SD = 2.49) participated in this study. Three MAs were assessed: coordination and strength (using the German Motor Test) and endurance (using a cycle ergometer test). EFs were assessed: inhibition and cognitive flexibility (Color-Word Interference Test) and working memory (Block Recall test); and academic performance by questionnaire asking for children’s grade point average.ResultsPearson correlations revealed associations of coordination and strength with EFs and associations of all three MAs with academic performance. A multiple regression model revealed that among the three MAs, coordination was the only significant predictor of EFs (β = 0.42, p = .001). Lastly, mediation analyses revealed that the association of MAs with academic performance was mediated by EFs (indirect effect: β = 0.167, p = .003). Regarding individual motor abilities, this was only true for coordination and strength, but not for endurance.ConclusionResults show that MAs and EFs are interrelated in PCS and that EFs mediate the relationship between coordination and strength with academic performance. This may be important for the design of future physical activity interventions to improve MAs, EFs and academic performance.     

The effects of lemon taste on attention,perceived exertion,and affect during a stepping task

ObjectivesTo better understand the effects of taste cues on delaying the attention shift from an external focus (dissociative) towards an internal focus (associative) as exercise intensity increases.DesignA between subjects' experimental design with random assignment to three groups: taste (lemon-flavored mouth guards), placebo (unflavored mouth guards), or control group (no mouth guards) was used. Participants reported perceived exertion, affect (i.e., pleasantness and arousal), and attention allocation before, during, and after performing a weighted stepping task.ResultsPerforming the task resulted in a gradual increase of perceived exertion, F (1.87, 74.89) = 63.05, p < .05, η_p² = .61, along with a shift from dissociative to associative attention, F (2.17, 86.68) = 35.57, p < .05, η_p² = .47 across all conditions. Additionally, participants reported feeling less pleasant and more aroused after task completion in all conditions. The lemon-flavored mouth guard failed to affect attention, F (4.33, 86.68) = 1.41, p = .23, η_p² = .07, perceived exertion, F (3.74, 74.86) = .38, p = .81, η_p² = .02, pleasantness, F (2, 40) = .126, p = .88, η_p² = .01, and arousal, F (2, 40) = 2.40, p = .10, η_p² = .10, differently than the other two conditions.ConclusionsThe study was one of the first to examine the effects of taste during an exertive task. Despite the non-significant effects of using a lemon-taste mouth guard on various cognitive variables (perception of exertion, attention allocation, pleasantness, and arousal), more scientific effort is needed to explore the effects of other tastes (e.g., sweet, bitter) and delivery methods (e.g., sprays, drops).     

Study of Sexual Concordance in Men and Women with Different Typologies of Adherence to the Sexual Double Standard

Background/ObjectiveSexual concordance (i.e., relationship between genital response and subjective sexual arousal) is higher in men than in women. Among the factors that could explain this difference would be the sexual double standard (SDS). Sexual concordance is examined by SDS typologies of adherence (egalitarian, man-favorable, and woman-favorable).MethodDuring exposure to a film with sexual content, genital response (penile circumference/vaginal pulse amplitude) and self-reported sexual arousal were recorded in 104 young adults (42 men and 62 women), distributed into SDS typologies of adherence on the basis of their scores on the Sexual Double Standard Scale.ResultsSexual concordance was obtained in men and women with egalitarian and man-favorable typology. Subjective sexual arousal explained a significant percentage of the variance in genital response in the egalitarian typology (men: R² = .32, p < .01; women: R² = .19, p < .05) and man-favorable typology (men: R² = .21, p < .05; women: R² = .23, p < .05).ConclusionsAgreement between genital responsiveness and subjective sexual arousal depends on DES adherence typology.     

Effect of psychostimulant medications on static balance performance in adults with attention deficit hyperactivity disorder: Within-subjects repeated-measure study

ObjectiveThis study examined the effect of psychostimulant medications nPS) on balance and functional motor performance in adults with attention-deficit/hyperactivity disorder (ADHD).MethodsParticipants completed two sessions (off-medication and on-medication) in a within-subjects repeated-measure study design. There was a minimum of seven days between the two sessions. During both sessions, participants stood for 30 s per condition on a force platform. The conditions were: feet-apart with 1) eyes-open and 2) eyes-closed; feet-together with 3) eyes-open and 4) eyes-closed. Participants performed three trials of timed up and go (TUG) and lateral step-up test (LSUT) during both sessions. Outcome measures were sway area (SA [cm²]), average sway velocity (SV [cm/s]), TUG average time (s), and average number of LSUT repetitions. Data were analyzed using multivariate repeated measures analysis of variance and paired t-tests for examining PS effects on balance (SA and SV) and functional motor performance (TUG and LSUT), respectively.ResultsThe sample included 45 adults (35 females; mean age = 28.4 ± 6.3 years). The repeated-measures MANOVA indicated that PS was associated with better SA [F(1,44) = 9.6; p = 0.003;η_p² = 0.18] but not with SV [F(1,44) = 1.0; p = 0.319;η_p² = 0.02]. PS was associated with significantly better SA with decreasing base-of-support [F(1,44) = 9.9; p = 0.003;η_p² = 0.18]. Additionally, PS use was associated with better TUG [t(1,44) = 2.65; p = 0.014;Cohen's d = 0.39] but not LSUT performances [t(1,44) = −0.68; p = 0.499;Cohen's d = −0.10].ConclusionsPS was associated with better SA and TUG in adults with ADHD. Further studies are needed to investigate the effects of PS on balance performance using rigorous designs in this population.ImpactHealthcare providers should screen for PS status and balance when treating adults with ADHD to enhance safe motor performance.     

Advanced age brings a greater reliance on visual feedback to maintain balance during walking

We implemented a virtual reality system to quantify differences in the use of visual feedback to maintain balance during walking between healthy young (n = 12, mean age: 24 years) and healthy old (n = 11, 71 years) adults. Subjects walked on a treadmill while watching a speed-matched, virtual hallway with and without mediolateral visual perturbations. A motion capture system tracked center of mass (CoM) motion and foot kinematics. Spectral analysis, detrended fluctuation analysis, and local divergence exponents quantified old and young adults’ dynamic response to visual perturbations. Old and young adults walked normally with comparable CoM spectral characteristics, lateral step placement temporal persistence, and local divergence exponents. Perturbed visual flow induced significantly larger changes in mediolateral CoM motion in old vs. young adults. Moreover, visual perturbations disrupted the control of lateral step placement and compromised local dynamic stability more significantly in old than young adults. Advanced age induces a greater reliance on visual feedback to maintain balance during waking, an effect that may compensate for degradations in somatosensation. Our findings are relevant to the early diagnosis of sensory-induced balance impairments and also point to the potential use of virtual reality to evaluate sensory rehabilitation and balance training programs for old adults.     

Corticomotor excitability of gluteus maximus and hip extensor strength: The influence of sex

PurposeTo compare hip extensor strength and corticomotor excitability (CME) of gluteus maximus (GM) between males and females. A secondary purpose was to determine if CME of GM is predictive of hip extensor strength.MethodThirty-two healthy individuals participated (15 males and 17 females). CME of GM was assessed using the input-output curve (IOC) procedure acquired from transcranial magnetic stimulation (average slope). Hip extensor strength was measured by a dynamometer during a maximal voluntary isometric contraction. Independent t-tests were used to compare CME of GM and peak hip extensor torque between males and females. Linear regression analysis was used to determine whether peak hip extensor torque was predicted by CME of GM.ResultCompared to males, females demonstrate lower peak hip extensor torque (4.42 ± 1.11 vs. 6.15 ± 1.72 Nm/kg/m2, p < 0.01) and lower CME of GM (1.36 ± 1.07 vs. 2.67 ± 1.30, p < 0.01). CME of GM was a significant predictor of peak hip extensor torque for males and females combined (r² = 0.36, p < 0.001).ConclusionOur findings support the premise that corticomotor excitability plays a role in the ability of a muscle to generate torque.