BASELINE trial: update in study design

Age-related changes in gait adaptability in response to unpredictable obstacles and stepping targets

The purpose of this study was to examine the relative influence of initial hand location on the direction and extent of planar reaching movements. Subjects performed a horizontal-plane reaching task with the dominant arm supported above a table top by a frictionless air-jet system. A start circle and a target were reflected from a horizontal projection screen onto a horizontally positioned mirror, which blocked the subject's view of the arm. A cursor, representing either actual or virtual finger location, was only displayed between each trial to allow subjects to position the cursor in the start circle. Prior to occasional "probe trials," we changed the start location of the finger relative to the cursor. Subjects reported being unaware of the discrepancy between cursor and finger. Our results indicate that regardless of initial hand location, subjects did not alter the direction of movement. However, movement distance was systematically adjusted in accord with the baseline target position. Thus when the hand start position was perpendicularly displaced relative to the target direction, neither the direction nor the extent of movement varied relative to that of baseline. However, when the hand was displaced along the target direction, either anterior or posterior, movements were made in the same direction as baseline trials but were shortened or lengthened, respectively. This effect was asymmetrical such that movements from anterior displaced positions showed greater distance adjustment than those from posterior displaced positions. Inverse dynamic analysis revealed substantial changes in elbow and shoulder muscle torque strategies for both right/left and anterior/posterior pairs of displacements. In the case of right/left displacements, such changes in muscle torque compensated changes in limb configuration such that movements were made in the same direction and to the same extent as baseline trials. Our results support the hypothesis that movement direction is specified relative to an origin at the current location of the hand. Movement extent, on the other hand, appears to be affected by the workspace learned during baseline movement experience.

Much effort over the past 50 years has been devoted to research on training, but little is known about recovery after intense running efforts with respect to specific modalities (ie. cryotherapy, passive recovery, etc.) utilized. Anecdotal evidence suggests that cold water immersion immediately following intense distance running efforts aids in next day performance perhaps by decreasing injury or increasing recovery. PURPPSE: This study compared 5km racing performance after 24 hrs with and without cold water immersion. METHODS: Using a within-subjects counterbalanced design, 12 well-trained (VO2max = 62.4 ml/kg/min) runners (9 males and 3 females) completed two successive (pre and post 24 hr passive recovery with and without cold water immersion) 5km performance trials, on two separate occasions, separated by 6–7 days of normal training. Immediately following the first baseline 5km trial, runners were treated with ice/cold water immersion for 12 min followed by 24 hrs of passive recovery (ICE). Another session involved two 5km time trials, a baseline trial and another trial after 24 hrs of passive recovery (CON). RESULTS: ICE (20:08 ± 2.0 min) was not significantly different (p = 0.09) from baseline (19:59 ±2.0 min). CON (19:59 ± 1.9 min) was significantly (p = 0.03) slower than baseline (19:49 ± 1.9 min). ICE HRave (175.3 ± 7.6 b/min) was significantly (p = 0.02) less than baseline (178.3 ± 9.8 b/min), yet CONHRave (177.3 ± 6.3 b/min) was identical to baseline (177.3 ± 7.3 b/min). ICE RPEend (19.2 ± 1.0) was significantly less (p = 0.03) than baseline (19.8 ± 0.5) while CON RPEend (19.5 ± 0.8) was not significantly different (p = 0.39) from baseline (19.6 ± 0.8). For the ICE trials, 7 participants ran a mean 24.0 ± 13.9 secs slower, 3 participants ran a mean 20.33 ± 6.7 secs faster, and 2 participants ran within 2.5 ± 0.7 secs of their first run. During the CON trials, 7 individuals ran a mean 20.6 ± 9.0 secs slower, 3 individuals ran a mean 13.3 ±6.8 secs faster, and 2 individuals ran within 6.5 ± 0.7 secs of their baseline trial. CONCLUSION: In general, cold water immersion minutely reduced the decline of next day running performance, yet individual variability existed. Efficacy of longer durations of cold water immersion immediately after distances equal to or greater than 5km may need to be further explored. Examining the effects of cold water immersion combined with longer passive recovery periods may also be of further interest.

The current study investigated the development of online reach control. Six- and 11-month-old infants reached for a toy while their hand position was tracked. The toy either remained stationary (baseline trials) or unexpectedly displaced left- or rightward during the reach (perturbation trials). To obtain a measure of online reach correction, we compared reaches in the perturbation trials to reaches in baseline trials using autoregression analysis. Infants of both age groups adjusted their reach trajectories in the direction of the displacement. Moreover, we divided the reaching movements into movement units, defined as the submovements of a reach between local minima in hand speed. Eleven-month-old infants adjusted their reach within the span of a single movement unit; corrections in 6-month-olds spanned multiple movement units. These results suggest that the reach control system has a rudimentary replanning capacity by 6months of age, which, with age, further develops to a more sophisticated online control mechanism for ongoing reaches.

The amount of resistance provided by the ACL (anterior cruciate ligament) to axial tibial rotation remains controversial. The goal of this study was to test the primary hypotheses that ACL transection would not significantly affect tibial rotation under the large impulsive loads associated with a simulated pivot landing but would increase anterior tibial translation. Twelve cadaveric knees (mean age of donors [and standard deviation] at the time of death, 65.0 ± 10.5 years) were mounted in a custom testing apparatus to simulate a single-leg pivot landing. A compound impulsive load was applied to the distal part of the tibia with compression (∼800 N), flexion moment (∼40 N-m), and axial tibial torque (∼17 N-m) in the presence of five trans-knee muscle forces. A differential variable reluctance transducer mounted on the anteromedial aspect of the ACL measured relative strain. With the knee initially in 15° of flexion, and after five combined compression and flexion moment (baseline) loading trials, six trials were conducted with the addition of either internal or external tibial torque (internal or external loading), and then six baseline trials were performed. The ACL was then sectioned, six baseline trials were repeated, and then six trials of either the internal or the external loading condition, whichever had initially resulted in the larger relative ACL strain, were carried out. Tibiofemoral kinematics were measured optoelectronically. The results were analyzed with a nonparametric Wilcoxon signed-rank test. Following ACL transection, the increase in the normalized internal tibial rotation was significant but small (0.7°/N-m ± 0.3°/N-m to 0.8°/N-m ± 0.3°/N-m, p = 0.012), while anterior tibial translation increased significantly (3.8 ± 2.9 to 7.0 ± 2.9 mm, p = 0.017). ACL transection leads to a small increase in internal tibial rotation, equivalent to a 13% decrease in the dynamic rotational resistance, under the large forces associated with a simulated pivot landing, but it leads to a significant increase in anterior tibial translation.

Although cardiac resynchronization therapy (CRT) improves functional capacity in heart failure patients, a blunted heart rate (HR) response remains after treatment. So we aimed to evaluate the feasibility of the physiological pacing rate (PPR) in CRT patients. A cohort of 30 clinical mildly symptomatic CRT patients underwent the six-minute walk test (6MWT). During the 6MWT, HR, blood pressure, and maximum walking distance were assessed. The measurements were obtained in a pre to post manner, with CRT at nominal settings and with the physiological phase (CRT PPR), in which HR was increased by 10% above the maximum HR achieved previously. The CRT cohort also comprised a matched control group (CRT CG). In the CRT CG, the 6MWT was repeated after the standard evaluation with no PPR. The evaluations were blinded for patients and for the 6MWT evaluator. During the 6MWT, CRT PPR led to an increase in walking distance of 40.5m (9.2%; P<0.0001) when compared with baseline trial. Additionally, CRT PPR increased the maximum walking distance compared with CRT CG 479.3±68.9m vs. 420.3±44.8m, respectively, P=0.001. In the CRT CG, CRT PPR increased the variation in walking distance, compared with baseline trials, respectively 2.40±3.8% vs. 9.25±7.0%, P=0.007. In mildly symptomatic CRT patients PPR is feasible, leading to improvements in functional capacity. In this regard, the efficacy of PPR must be confirmed by controlled randomized trials.

We conducted a meta‐analysis to assess the effect of different body mass index on surgical wound infection after colorectal surgery. A systematic literature search up to November 2022 was performed and 2349 related studies were evaluated. The chosen studies comprised 15 595 colorectal surgery subjects participated in the selected studies' baseline trials; 4390 of them were obese according to the selected body mass index cut‐off used to measure obesity in the selected studies, while 11 205 were nonobese. Odds ratio (OR) with 95% confidence intervals (CIs) were calculated to assess the effect of different body mass index on wound infection after colorectal surgery by the dichotomous methods with a random or fixed effect model. The body mass index ≥30 kg/m2 resulted in significantly higher surgical wound infection after colorectal surgery (OR, 1.76; 95% CI, 1.46–2.11, P < .001) compared with the body mass index <30 kg/m2. The body mass index ≥25 kg/m2 resulted in significantly higher surgical wound infection after colorectal surgery (OR, 1.64; 95% CI, 1.40–1.92, P < .001) compared with the body mass index <25 kg/m2. The subjects with higher body mass index had a significantly higher surgical wound infection after colorectal surgery compared with the subjects with normal body mass index.

BackgroundAssessment of functional impairment following ischaemic stroke is essential to determine outcome and efficacy of intervention in both clinical patients and pre-clinical models. Although paradigms are well described for rodents, comparable methods for large animals, such as sheep, remain limited. This study aimed to develop methods to assess function in an ovine model of ischaemic stroke using composite neurological scoring and gait kinematics from motion capture.MethodsMerino sheep (n = 26) were anaesthetised and subjected to 2 hours middle cerebral artery occlusion. Animals underwent functional assessment at baseline (8-, 5-, and 1-day pre-stroke), and 3 days post-stroke. Neurological scoring was carried out to determine changes in neurological status. Ten infrared cameras measured the trajectories of 42 retro-reflective markers for calculation of gait kinematics. Magnetic resonance imaging (MRI) was performed at 3 days post-stroke to determine infarct volume. Intraclass Correlation Coefficients (ICC's) were used to assess the repeatability of neurological scoring and gait kinematics across baseline trials. The average of all baselines was used to compare changes in neurological scoring and kinematics at 3 days post-stroke. A principal component analysis (PCA) was performed to determine the relationship between neurological score, gait kinematics, and infarct volume post-stroke.ResultsNeurological scoring was moderately repeatable across baseline trials (ICC > 0.50) and detected marked impairment post-stroke (p < 0.05). Baseline gait measures showed moderate to good repeatability for the majority of assessed variables (ICC > 0.50). Following stroke, kinematic measures indicative of stroke deficit were detected including an increase in stance and stride duration (p < 0.05). MRI demonstrated infarction involving the cortex and/or thalamus (median 2.7 cm3, IQR 1.4 to 11.9). PCA produced two components, although association between variables was inconclusive.ConclusionThis study developed repeatable methods to assess function in sheep using composite scoring and gait kinematics, allowing for the evaluation of deficit 3 days post-stroke. Despite utility of each method independently, there was poor association observed between gait kinematics, composite scoring, and infarct volume on PCA. This suggests that each of these measures has discreet utility for the assessment of stroke deficit, and that multimodal approaches are necessary to comprehensively characterise functional impairment.

Background: Papers describing the results of a randomised trial should include a baseline table that compares the characteristics of randomised groups. Researchers who fraudulently generate trials often unwittingly create baseline tables that are implausibly similar (under-dispersed) or have large differences between groups (over-dispersed). I aimed to create an automated algorithm to screen for under- and over-dispersion in the baseline tables of randomised trials. Methods: Using a cross-sectional study I examined 2,245 randomised controlled trials published in health and medical journals on PubMed Central. I estimated the probability that a trial's baseline summary statistics were under- or over-dispersed using a Bayesian model that examined the distribution of t-statistics for the between-group differences, and compared this with an expected distribution without dispersion. I used a simulation study to test the ability of the model to find under- or over-dispersion and compared its performance with an existing test of dispersion based on a uniform test of p-values. My model combined categorical and continuous summary statistics, whereas the uniform test used only continuous statistics. Results: The algorithm had a relatively good accuracy for extracting the data from baseline tables, matching well on the size of the tables and sample size. Using t-statistics in the Bayesian model out-performed the uniform test of p-values, which had many false positives for skewed, categorical and rounded data that were not under- or over-dispersed. For trials published on PubMed Central, some tables appeared under- or over-dispersed because they had an atypical presentation or had reporting errors. Some trials flagged as under-dispersed had groups with strikingly similar summary statistics. Conclusions: Automated screening for fraud of all submitted trials is challenging due to the widely varying presentation of baseline tables. The Bayesian model could be useful in targeted checks of suspected trials or authors.

During a baseline trial, participants attempted to produce a 60-sec. interval while working at either a simple tracing task or others that involved mirror-tracing. Subsequent practice with the assigned task, expected to reduce the need for allocation of attention to mirror-tracing for those groups, produced predictable effects on a second trial of duration producing. Those performing mirror-tracing reduced production rimes on the postpractice trial, while those performing simple tracing showed no change after practice. These results are interpreted within the attentional allocation model of estimation of prospective duration.

External feedback during walking improves measures of plantar pressure in individuals with chronic ankle instability

In two experiments we evaluated whether a perceiver’s prior expectations could alone obliterate his or her awareness of a salient visual stimulus. To establish expectancy, observers first made a demanding visual discrimination on each of three baseline trials. Then, on a fourth, critical trial, a single, salient and highly visible object appeared in full view at the center of the visual field and in the absence of any competing visual input. Surprisingly, fully half of the participants were unaware of the solitary object in front of their eyes. Dramatically, observers were blind even when the only stimulus on display was the face of U.S. President Barack Obama. We term this novel, counterintuitive phenomenon, Barack Obama Blindness (BOB). Employing a method that rules out putative memory effects by probing awareness immediately after presentation of the critical stimulus, we demonstrate that the BOB effect is a true failure of conscious vision.

Attentional shifting and disengagement in Rett syndrome.

Echolocating bats often operate in the presence of conspecifics and in cluttered environments, which can be characterized as a “cocktail party nightmare.” Each bat's sonar vocalization can result in an echo cascade from objects distributed in direction and range. Adding to the acoustic clutter are the signals from neighboring bats. Past studies demonstrate that bats adapt their echolocation to avoid signal jamming from conspecifics by adjusting the frequencies of their vocalizations, as well as going silent. When bats fly alone in densely cluttered environments, they adjust the frequencies of call pairs to disambiguate overlapping echo streams. How do echolocating bats adapt to both conspecific signals and clutter? We sought to answer this question by flying big brown bats in a large room equipped with high-speed video and audio recording equipment. In baseline trials, bats flew alone in an empty room and were later introduced to an artificial forest, first individually and later in pairs. The echolocation behavior and flight paths are analyzed to evaluate the spectro-temporal adjustments of bat calls and silent behavior as animals progressed from open room, to forest, to forest with conspecifics. The results shed light on how echolocating bats adapt to a “cocktail party nightmare.”

Jessica Moon1, Christian Espitia2, Landon Hiebert2, Christopher A. Fahs2, Lindy M. Rossow2 1Lindenwood University, St. Charles, Missouri; 2Lindenwood University-Belleville, Belleville Illinois Pre-exercise consumption of placebo has been shown to improve resistance and endurance exercise performance. However, the effects of placebo ingestion on graded exercise test performance have not been widely reported in the literature. PURPOSE: The purpose of this study was to examine the effects of honest (subjects were told they were consuming placebo) or dishonest (subjects were told they were consuming a pre-workout supplement) placebo ingestion on VO2peak values determined during a maximal treadmill graded exercise test. A secondary purpose of this study was to examine the effects of placebo consumption on isometric handgrip performance. We hypothesized that pre-exercise ingestion of both placebo conditions would result in increased VO2peak and handgrip performance compared to control. METHODS: 28 males (178.4 ± 6.94 cm, 83.3 ± 14.8 kg, 22.6 ± 2.3 yrs.) and 13 females (166.4 ± 8.49 cm, 73.6 ± 20 kg, 26.4 ± 11 yrs.) participated in this study. In a randomized, cross-over design, subjects performed treadmill VO2peak and isometric handgrip testing after consumption of honest placebo (HP) or dishonest placebo (DP). In addition, a third baseline trial (CON) was performed to establish performance values that were unaffected by a perceived placebo effect due to supplementation. All outcomes were assessed for normality using the Shapiro-Wilks test. When assumptions of normality were violated, log transformations were computed. However, transformations did not improve model assumptions. Therefore, non-transformed data is reported. One-way ANOVAs were used to analyze VO2peak and handgrip strength data across conditions. Alpha was set at 0.05 prior to all analyses. RESULTS: Significant between-groups differences (p < 0.05) were not detected for relative VO2peak (CON = 46.2 ± 9.3 mL/kg/min; HP = 46.7 ± 10 mL/kg/min; DP = 46.6 ± 9.6 mL/kg/min) or for maximal handgrip strength (CON = 43 ± 9.6 kg; HP = 44.1 ± 12.4 kg; DP = 43.4 ± 12.1 kg). CONCLUSION: Administration of honest or dishonest placebo immediately prior to VO2peak and handgrip testing had no effect on performance compared to control. The VO2peak and isometric handgrip tests were found to be robust exercise tests not significantly influenced by perceived pre-workout supplement consumption