Repeated-measures Crossover Design Research Articles

Virtual Reality Exercise with Autonomy Support Increases Positive Affect During Time Trial Exercise.

Background: Being able to choose elements of an exercise session, known as autonomy support, improves motor performance and psychological responses. Virtual reality (VR) programs provide many options for embedding autonomy support in exercise sessions. The purpose of this study was to investigate the effects of autonomy support in a VR setting on physiological and psychological responses to self-regulated rowing exercise. Methods: Using a repeated-measures crossover design, healthy untrained men and women (N = 20, age = 23.0 ± 7.4) completed exercise sessions on a rowing ergometer coupled with a head-mounted immersive VR application. In the Choice condition, participants chose the virtual environment, and in the Control condition, the environment was assigned to the participant. Participants were instructed to complete 1500 m as quickly as possible in both conditions, while ratings of perceived exertion, affective valence, and heart rate were recorded throughout the trials. Finishing time and remembered pleasure were assessed at the end of each session. Repeated-measures analyses with an alpha level of 0.05 were used for all variables as appropriate, with Bonferroni adjustments applied for any post hoc tests. Results: There was a main effect of condition on affective valence which was higher in Choice (2.07 ± 1.67) than Control (1.64 ± 2.12, P = 0.03, η2 = 0.22). No other differences were detected between conditions for finishing time or the remaining variables. Conclusion: During self-regulated exercise accompanied by an immersive VR application, being able to choose the virtual environment oneself leads to a more positive affective state without compromising exercise effort, physiological strain, or performance.

Vascular limitations in blood pressure regulation with age in women: Insights from exercise and acute cardioselective β-blockade.

Younger women rely on altering cardiac output ( ) to regulate blood pressure (BP). In contrast, older women rely more on altering vascular tone. However, evidence suggests that the ability to alter systemic vascular conductance (SVC) is diminished in older women. In the present study, cardioselective β-blockade was utilized to diminish the relative contribution of to BP regulation and thereby evaluate age-related vascular limitations in women at rest and during large muscle dynamic exercise. Younger (n=13, mean age 26.0 years) and older (n=14, mean age 61.8 years) healthy women performed submaximal bouts of semi-recumbent cycling exercise at varying intensities while receiving an intravenous infusion of esmolol, a β1-antagonist, or saline control in a repeated-measures crossover design. was attenuated during esmolol infusion, with greater reductions during exercise (moderate, -1.0 (95% CI, -1.6 to -0.5)L/min, P<0.001; heavy, -2.0 (95% CI, -2.6 to -1.5)L/min, P<0.001) than seated rest (-0.5 (95% CI, -1.1 to 0.0)L/min, P=0.048), and this reduction was not significantly different between age groups (P=0.122). Older women exhibited a greater attenuation in mean arterial pressure (MAP) during esmolol (-7 (95% CI, -9 to -4) mmHg, P<0.001) relative to younger women (-2 (95% CI, -5 to 0) mmHg, P=0.071). These changes coincided with a greater reduction of SVC in the younger women during esmolol (-15 (95% CI, -20 to -10)mL/min/mmHg, P<0.001) compared to older women (-3 (95% CI, -9 to 2)mL/min/mmHg, P=0.242). Together, these findings provide evidence that older, postmenopausal women have a diminished ability to adjust SVC in order to regulate MAP.

Wearing surgical face mask has no significant impact on auscultation assessment.

During the COVID-19 pandemic, universal mask-wearing became one of the main public health interventions. Because of this, most physical examinations, including lung auscultation, were done while patients were wearing surgical face masks. The aim of this study was to investigate whether mask wearing has an impact on pulmonologist assessment during auscultation of the lungs. This was a repeated measures crossover design study. Three pulmonologists were instructed to auscultate patients with previously verified prolonged expiration, wheezing, or crackles while patients were wearing or not wearing masks (physician and patients were separated by an opaque barrier). As a measure of pulmonologists' agreement in the assessment of lung sounds, we used Fleiss kappa (K). There was no significant difference in agreement on physician assessment of lung sounds in all three categories (normal lung sound, duration of expiration, and adventitious lung sound) whether the patient was wearing a mask or not, but there were significant differences among pulmonologists when it came to agreement of lung sound assessment. Clinicians and health professionals are safer from respiratory infections when they are wearing masks, and patients should be encouraged to wear masks because our research proved no significant difference in agreement on pulmonologists' assessment of auscultated lung sounds whether or not patients wore masks.

Effect of methylphenidate on oculomotor function in individuals with multiple sclerosis: a pilot randomized placebo-controlled trial

IntroductionIndividuals with multiple sclerosis (MS) frequently experience visual and oculomotor symptoms that may impact and confound neuropsychological assessments of information processing speed (IPS). In this study, we examined the effect of the psychostimulant methylphenidate on oculomotor function and the association between change in oculomotor speed and change in information processing speed.MethodsWe used a repeated measures crossover design in which a sample of 11 participants with MS were randomly assigned to one of two treatment arms: one that received methylphenidate for 4 weeks and another that received a placebo for 4 weeks. After a 7-day washout period, the treatments were crossed over. The King Devick test, the Symbol Digit Modalities Test, and the Paced Auditory Serial Addition Test were administered at baseline and after each of the two study arms.ResultsWe found a significant improvement in oculomotor speed in the methylphenidate condition as compared to placebo. This improvement was significantly correlated with improvement on a visuomotor assessment of IPS (Symbol Digit Modalities Test), but no such association was found for an auditory-verbal assessment of IPS (Paced Auditory Serial Addition Test).DiscussionThese findings suggest that individuals with MS experience improved oculomotor speed while taking methylphenidate, which may, in turn, improve performance on assessments of IPS with visuomotor demands.

The Acute Effects of Ball Pressure on Anticipation Timing Following a Series of Purposeful Headers in Adult Football (Soccer) Players.

The purpose of this study is to investigate the acute effects of ball pressure on anticipation timing following a series of purposeful headers in adult football (soccer) players. There is evidence to suggest acute neurophysiological changes to the brain following purposeful heading; this may lead to altered anticipation timing as a result, potentially having future safety implications for players. A repeated measures crossover design was used. Seventeen participants aged between 20 and 30 years performed (i) 20 rotational headers with a lower-pressure match ball (58.6 kPa; 8.5 psi), (ii) 20 rotational headers with a higher-pressure match ball (103.4 kPa; 15 psi), or (iii) 20 non-headers (kicks) as a control each on separate days. The effect of ball pressure on anticipation timing accuracy, measured as absolute, constant, and variable errors, was assessed before and immediately after each intervention session using an anticipation timing task. Differences between group means were compared using repeated measures ANOVA and linear mixed effects models, with p-values of <0.05 considered statistically significant. No significant differences in anticipation timing accuracy across interventions were detected between control, occluded, and non-occluded trials. This finding differs from the previous literature regarding the measurable, acute effects of purposeful heading. The anticipation timing task may lack sensitivity for detecting the effects of repeated heading on brain function.

Does report modality modulate psychophysical sensitivity? The jury remains out

Scientific studies of perception use motoric reports as the principal means of communicating subjective experience. In such experiments, a widely held and implicit assumption is that the motor action conveys but does not tamper with perceptual experience. We tested nine observers on a luminance detection task in a cross-over repeated measures design. In separate conditions, observers reported their detection via movements of either their hands or eyes. We found only anecdotal evidence for any modality-dependent effect on psychophysical sensitivity. We also reanalyzed an existing dataset from which deployed a similar detection paradigm involving hand and eye reports. In the four paradigm variants tested, we again only found anecdotal evidence for the effect of report modality on psychophysical sensitivity. Both studies reported here provide only anecdotal evidence; thus, whether we can replicate report-dependent perceptual effects still needs to be resolved. We argue why this remains an important question for consciousness research and why it deserves more rigorous and high-powered replication attempts.

Electrical matrix stimulation suppresses acute itch independently of activation of sleeping nociceptors.

Itch can be reduced by pain. Activation of sleeping nociceptors (CMi) is a crucial mechanism for the peripheral component of intense and long-lasting pain. Thus, activation of CMi might be especially effective in itch reduction. Electrical stimulation using sinusoidal pulses activates CMi with tolerable pain intensity, whereas short rectangular pulses with low intensity do not. In humans, histaminergic itch is mediated by histamine-sensitive CMi, whereas other pruritogens activate polymodal nociceptors (CM). In a psychophysical approach in a balanced crossover repeated-measures design in healthy volunteers, we activated nociceptors by two different electrical stimulation paradigms via a matrix electrode: 4 Hz sinusoidal pulses that activate C-nociceptors including CMi or 4 Hz rectangular stimuli to activate nociceptors excluding CMi. After 5-min stimulation, itch was induced by either histamine iontophoresis or application of cowhage spicules. Itch ratings were assessed via a numerical rating scale (NRS). Electrical 4 Hz sine wave stimulation (0.1 mA) with low pain ratings of 1.5 (NRS; 0-10) induced an axon reflex erythema (3 cm2 ), indicating activation of CMi, whereas rectangular 0.2 ms pulses (average 0.91 mA) with the same pain rating did not. Both electrical stimulation paradigms reduced itch magnitude over time evoked by either histamine or cowhage to a similar extent. Peak maximum itch evoked by histamine was reduced by both stimulation paradigms, but not cowhage maximum itch. Since electrical stimulation with the rectangular pulse paradigm reduces itch to a similar extent as the sine wave stimulation paradigm, the input of CMi is not necessarily required for itch suppression. The input of A-fibres and polymodal nociceptors, similarly, as also achieved by scratching, seems to be sufficient for both forms of chemically evoked itch. Since activation of CMi does not provide additional benefit for itch suppression, spinal pain pathways transmitted via CM versus CMi have differential effects on itch-processing circuits. This is important knowledge for using electrical matrix stimulation as itch suppressor since activation of sleeping nociceptors either requires significantly painful stimulation paradigms or specialized stimulation paradigms as sinusoidal pulses. An alternative approach using half-sine wave pulses with low pain intensity activating specifically polymodal nociceptors to suppress itch via matrix electrode stimulation may be considered.

How to analyze continuous and discrete repeated measures in small-sample cross-over trials?

To optimize the use of data from a small number of subjects in rare disease trials, an at first sight advantageous design is the repeated measures cross-over design. However, it is unclear how these within-treatment period and within-subject clustered data are best analyzed in small-sample trials. In a real-data simulation study based upon a recent epidermolysis bullosa simplex trial using this design, we compare non-parametric marginal models, generalized pairwise comparison models, GEE-type models and parametric model averaging for both repeated binary and count data. The recommendation of which methodology to use in rare disease trials with a repeated measures cross-over design depends on the type of outcome and the number of time points the treatment has an effect on. The non-parametric marginal model testing the treatment-time-interaction effect is suitable for detecting between group differences in the shapes of the longitudinal profiles. For binary outcomes with the treatment effect on a single time point, the parametric model averaging method is recommended, while in the other cases the unmatched generalized pairwise comparison methodology is recommended. Both provide an easily interpretable effect size measure, and do not require exclusion of periods or subjects due toincompleteness.

A preliminary study on the effect of loaded and unloaded exercise on N-propeptide of type II collagen and serum cartilage oligomeric matrix protein activity of articular cartilage in healthy young adults.

The serum concentration of cartilage oligomeric matrix protein (sCOMP) is considered a mechanosensitive biomarker of articular cartilage turnover, and N-propeptide of type II collagen (PIIANP), a proposed biomarker of type II collagen synthesis. Few studies have investigated the anabolic and turnover response of articular cartilage in response to acute changes in body mass during exercise. Using a repeated measure cross-over design, 15 healthy adults (age 18-30 years) performed three 30 min bouts of treadmill walking exercise under three loading conditions: (1) control (no alteration to body mass); (2) loaded (12% increase in body mass using a weighted vest); and (3) unloaded (12% decrease in body mass using lower body positive pressure). Venous blood was collected before, immediately after, and 15 and 30 min after exercise to investigate cartilage turnover (sCOMP) and anabolism (PIIANP). A main time effect (p≤0.05) revealed that sCOMP levels were significantly greater post-exercise (for all three body loading conditions) as compared to before exercise, 15 and 30 min post-exercise. There was a significant condition×time interaction (p≤0.05) for PIIANP, indicating that in the loaded condition, PIIANP concentrations at 15 min post-exercise were 13.8% greater than immediately following exercise, and 12.9% greater than before exercise. In summary, sCOMP concentration was acutely increased with all three loading conditions. However, PIIANP increased only after exercise in the loaded condition, suggesting an acute anabolic effect on articular cartilage. NCT05925244.

DMSO potentiates the suppressive effect of dronabinol on sleep apnea and REM sleep in rats

IntroductionDimethyl sulfoxide (DMSO) is an amphipathic molecule with innate biological activity that also is used to dissolve both polar and nonpolar compounds in preclinical and clinical studies. Recent investigations of dronabinol, a cannabinoid, dissolved in DMSO demonstrated decreased sleep apnea frequency and time spent in REM sleep in rats. Here, we tested the effects of dronabinol dissolved in 25% DMSO diluted in phosphate-buffered saline (PBS) to rule out potentiating effects of DMSO.MethodsSprague–Dawley rats were anesthetized and implanted with bilateral stainless steel screws into the skull for electroencephalogram recording and bilateral wire electrodes into the nuchal muscles for electromyogram recording. Each animal was recorded by polysomnography. The study was a fully nested, repeated measures crossover design, such that each rat was recorded following each of 8 intraperitoneal injections separated by three days: vehicle (25% DMSO/PBS); vehicle and CB1 antagonist (AM 251); vehicle and CB2 antagonist (AM 630); vehicle and CB1/CB2 antagonist; dronabinol (CB1/CB2 agonist); dronabinol and CB1 antagonist; dronabinol and CB2 antagonist; and dronabinol and CB1/CB2 antagonists. Sleep was manually scored into NREM and REM stages, and sleep apneas were quantified.ResultsDronabinol dissolved in 25% DMSO did not suppress sleep apneas or modify sleep efficiency compared to vehicle controls, in contrast to previously published results. However, dronabinol did suppress REM sleep, which is in line with previously published results.ConclusionsDronabinol in 25% DMSO partially potentiated dronabinol’s effects, suggesting a concomitant biological effect of DMSO on breathing during sleep.

Exploring the use of an under-desk leg swing device during employee aptitude testing and implications on work performance and productivity.

As modern occupations become more sedentary, desk-bound workers are more at risk of chronic diseases. Active workstations have gained popularity in the workplace, but there remain concerns about their impact on cognitive function. This study investigated the use of a novel under-desk leg swing device on cognitive ability in the workplace compared to sitting. Cognitive ability was measured using a pre-employment aptitude test (CCAT), and perceived outcomes were analyzed via self-report questionnaires. Using a randomized, repeated measures crossover design, 18 undergraduate students undertook the CCAT while using the under-desk leg swing device and while sitting only (Experiment 1). 9 students returned two to three weeks later to repeat testing (Experiment 2). In Experiment 1, CCAT scores did not differ significantly between the under-desk leg swing device and sitting (mean difference (MD) = -1.056, standard error (SE) = 1.302,p = 0.429, d = -0.16). Effect sizes of 0.554 were observed for perceived alertness, 0.446 for attention, 0.446 for focus, and 0.564 for enjoyment, but there were no significant differences between the two conditions. CCAT scores were significantly higher in Experiment 2 than in Experiment 1 (MD = 8.444, SE = 2.410,p = 0.008, d = 1.64). Based on Experiment 1, the findings suggest that the use of the under-desk leg swing device promotes movement without detriment to neither workflow nor cognitive ability relevant to employee aptitude compared to sitting.

Foot Cooling between Interval Bouts Enhances Repeated Lower Limb Power Performance: The Role of Delaying Fatigue.

This study aimed to investigate whether interbout foot cooling (FC) may enhance repeated lower limb power performance and the corresponding physiological responses based on interset FC, which has been demonstrated to enhance leg-press performance. In a repeated-measures crossover design, ten active men (aged 21.5 ± 1.5 years, exercising >3 times per week) performed four bouts of 10-s cycle ergometer sprints with interbout FC at 10°C water for 2.5 min or non-cooling (NC) with a 5-day interval. The results indicated that FC elicited higher total work (27.57 ± 5.66 kJ vs. 26.55 ± 5.76 kJ) and arousal scores than NC (p < 0.05). Furthermore, under the NC condition, participants decreased mean power (p < 0.05) with no alteration of vastus lateralis (VL) electromyography (EMG) activities after the second bout; whereas under the FC condition, participants maintained steady mean power accompanied by increased VL EMG activities in the last two bouts (p < 0.05). Jointly, participants had higher mean power ([3rd = 10.14 ± 1.15 vs. 9.37 ± 1.30; 4th = 9.79 ± 1.22 vs. 9.23 ± 1.27] W/kg) and VL EMG activities in the last two bouts under the FC than NC condition (p < 0.05). However, perceived exertion and the heart rate were comparable between the two conditions (p > 0.05). In conclusion, interbout FC elicited a higher arousal level and repeated lower limb power performance, which could be explained by delaying peripheral fatigue via increasing excitatory drive and recruiting additional motor units to compensate for fatigue-related responses and power decrements.

Dry food affects the oxidative/antioxidant profile of dogs.

Including adequate concentrations of antioxidants in dog diets has been recommended to reduce their vulnerability to the action of free radicals and reactive oxygen species (ROS). Oxidative stress in dogs has been associated with a wide range of diseases and disorders, as well as with ageing. There are few reports about the influence of diet on dog's antioxidant profile and oxidative stress. The objective of this study was to evaluate the effect of four types of dry dog food on the oxidative/antioxidant profile of dogs. Six Beagle dog males were used. The study included four experimental diets (dry foods A-D). Each dry food was supplied for 5 weeks to all dogs, for a total of 24 weeks, including an adaptation week between one food and another. For each dry dog food, the total phenolic content (TPC), total antioxidant capacity (TAC) and cytotoxicity were evaluated. Each week, a blood sample was collected to measure ROS and TAC of plasma. A crossover repeated measures design was used. Mixed models were adjusted, and means were compared using the Tukey test. Food A had the highest values for TPC and TAC. Food C had the lowest levels of ROS, whereas food B had the highest TAC in the blood plasma. The dog had a significant influence on the redox state of its blood plasma, even when the same dog was fed the different dry foods. Dry dog food influences the oxidative/antioxidant profile of dog's blood plasma; however, this seems to be unrelated to the antioxidant profile of the food.

Use of a habituation-dishabituation test to determine canine olfactory sensitivity.

The habituation-dishabituation (H-D) paradigm is an established measure of sensory perception in animals. However, it has rarely been applied to canine olfaction. It proposes that animals will lose interest in, or habituate to, a stimulus after successive exposures but will regain interest in, or dishabituate to, a novel stimulus if they can perceive it. This study assessed an H-D test's practicability to determine dogs' olfactory detection thresholds (ODTs) for a neutral odorant. A random selection of mixed-breed pet dogs (n= 26) participated in two H-D tests in a repeated-measures crossover design. They were first habituated to a carrier odor and then presented with either ascending concentrations of n-amyl acetate in the known ODT range (experimental condition) or repeated carrier odor presentations (control condition). No single odor concentration elicited dishabituation in the majority of the dogs. However, individual dogs dishabituated at differing experimental concentrations significantly more often than in the control condition (p= .012). These findings provide some tentative support for using this method in studying canine olfaction. However, further assessment and refinement are needed before it can be a viable alternative to traditional ODT measurement.

Effects of captions, transcripts and reminders on learning and perceptions of lecture capture

Lecture capture is popular within Higher Education, but previous research suggests that students do not always optimally select content to review, nor do they make the most of specific functions. In the current study conducted in the 2019/20 academic year, we used a repeated-measures crossover design to establish the effects of transcripts with closed captioning, and email reminders, on use (self-reported and system analytics), perceptions of lecture capture and student performance, as measured by multiple-choice question (MCQ) tests designed to assess the module learning outcomes. System analytics (N = 129) and survey data (N = 42) were collected from students alongside qualitative data from semi-structured interviews (N = 8). We found that students value lecture capture highly, but do not access it extensively during the teaching period. The availability of transcripts and closed captions did not impact the amount of capture use or performance on MCQ tests, but did result in more positive perceptions of capture, including increased likelihood of recommending it to others. The use of email reminders referring students to specific segments of capture and reminding them of the functionality had no impact on any measure, although qualitative data suggested that the content of reminders may be used in revision rather than during the teaching period, which fell outside the period we investigated. Collectively, these data suggest that the use of captions and transcripts may be beneficial to students by allowing dual processing of visual and audio content, and a searchable resource to help consolidate their learning but there is little evidence to support reminders.

A crossover control study of three methods of heat acclimation on the magnitude and kinetics of adaptation.

What is the central question to the study? Are primary indices of heat adaptation (e.g., expansion of plasma volume and reduction in resting core temperature) differentially affected by the three major modes of short-term heat acclimation, that is, exercise in the heat, hot water immersion and sauna? What it the main finding and its importance? The three modes elicited typical adaptations expected with short-term heat acclimation, but these were not significantly different between modes. This comparison has not previously been made and highlights that individuals can expect similar adaptation to heat regardless of the mode used. Heat acclimation (HA) can improve heat tolerance and cardiovascular health. The mode of HA potentially impacts the magnitude and time course of adaptations, but almost no comparative data exist. We therefore investigated adaptive responses to three common modes of HA, particularly with respect to plasma volume. Within a crossover repeated-measures design, 13 physically active participants (five female) undertook four, 5-day HA regimes (60min/day) in randomised order, separated by ≥4weeks. Rectal temperature (Tre ) was clamped at neutrality via 36.6°C (thermoneutral) water immersion (TWI; i.e., control condition), or raised by 1.5°C via heat stress in 40°C water, sauna (55°C, 52% relative humidity), or exercise in humid heat (40°C, 52% relative humidity; ExH). Adaptation magnitude was assessed as the pooled response across days 4-6, while kinetics was assessed via the 6-day time series. Plasma volume expansion was similar in all heated conditions but only higher than TWI in exercise in the heat (ExH) (by 4%, P=0.036). Approximately two-thirds of the expansion was attained within the initial 24h and was moderately related to that present on day 6, regardless of HA mode (r=0.560-0.887). Expansion was mediated by conservation of both sodium and albumin content, with little evidence for these having differential roles between modes (P=0.706 and 0.320, respectively). Resting Tre decreased by 0.1-0.3°C in all heated conditions, and systolic blood pressure decreased by 4mmHg, but not differentially between conditions (P≥0.137). In conclusion, HA mode did not substantially affect the magnitude or rate of adaptation in key resting markers of short-term HA.

The Acute and Delayed Effects of Foam Rolling Duration on Male Athlete’s Flexibility and Vertical Jump Performance

Foam rolling (FR) durations totaling ≤60 s per muscle are reported to acutely increase flexibility and vertical jump performance. However, limited research has investigated whether these benefits can outlast the inactive post-warmup preparatory period that typically separates warmups from the start of sporting competition. Eleven male athletes (height 1.77 0.09 m, body mass 78.0 17.0 kg, age 22 2 years) completed familiarization, followed by three experimental trials in a randomized and counterbalanced repeated measures crossover design. Trials commenced with 5 min jogging, before ankle dorsiflexion range of motion (ADF-ROM), sit and reach (S&amp;R), countermovement jump (CMJ) and squat jump (SJ) baseline testing. Participants then sat inactively for 10 min (control) or performed lower extremity FR totaling either 30 (30FR) or 60 s (60FR) that targeted four agonist-antagonist leg muscles. Testing was then repeated before and after a simulated inactive 15 min post-warmup preparatory period to establish the acute and delayed effects of FR on performance. A two-way repeated measures analysis of variance was used to identify any significant interaction effects between conditions (30FR, 60FR, control) and timepoint (baseline, acute, delayed). No significant condition x timepoint interaction effect was detected for the ADF-ROM (f = 1.63, p = 0.19), S&amp;R (f = 0.80, p = 0.54), CMJ ((f = 0.83, p = 0.99) or SJ (f = 0.66, p = 0.99). Therefore, FR totaling ≤60 s appears insufficient to enhance flexibility or vertical jump performance in male athletes.

Effects of Hinged versus Floor-Reaction Ankle-Foot Orthoses on Standing Stability and Sit-to-Stand Performance in Children with Spastic Diplegic Cerebral Palsy.

Hinged ankle-foot orthoses (HAFOs) and floor reaction ankle-foot orthoses (FRAFOs) are frequently prescribed to improve gait performance in children with spastic diplegic cerebral palsy (CP). No study has investigated the effects of FRAFO on sit-to-stand (STS) performance nor scrutinized differences between the application of HAFOs and FRAFOs on postural control. This study compared the effects of HAFOs and FRAFOs on standing stability and STS performance in children with spastic diplegic CP. Nine children with spastic diplegic CP participated in this crossover repeated-measures design research. Kinematic and kinetic data were collected during static standing and STS performance using 3-D motion analysis and force plates. Wilcoxon signed ranks test was used to compare the differences in standing stability and STS performance between wearing HAFOs and FRAFOs. The results showed that during static standing, all center of pressure (COP) parameters (maximal anteroposterior/mediolateral displacement, maximal velocity, and sway area) were not significantly different between FRAFOs and HAFOs. During STS, the floor reaction force in the vertical direction was significantly higher with FRAFOs than with HAFOs (p = 0.018). There were no significant differences in the range of motion in the trunk, knee, and ankle, the maximal velocity of COP forward displacement, completion time, and the force of hip, knee, and ankle joints between the two orthoses. The results suggest both FRAFOs and HAFOs have a similar effect on standing stability, while FRAFOs may benefit STS performance more compared to HAFOs.

Effect of bio-banding on physiological and technical-tactical key performance indicators in youth elite soccer

ABSTRACT Bio-banding has been introduced to reduce the impact of inter-individual differences due to biological maturation among youth athletes. Existing studies in youth soccer have generally examined the pilot-testing application of bio-banding. This is the first study that investigated whether bio-banded (BB) versus chronological age (CA) competition affects reliable physiological and technical-tactical in-game key performance indicators (KPIs) using a randomized cross-over repeated measures design. Sixty-five youth elite soccer players from the under-13 (U13) and under-14 (U14) age category and with maturity offsets (MO) between −2.5 and 0.5 years, competed in both a BB and CA game. For statistical analysis, players were divided into four sub-groups according to CA and MO: U13MOlow (CA ≤ 12.7, MO ≤ −1.4), U13MOhigh (CA ≤ 12.7, MO > −1.4), U14MOlow (CA > 12.7, MO ≤ −1.4), U14MOhigh (CA > 12.7, MO > −1.4). The two-factor mixed ANOVA revealed significant (p < .05) interactions between competition format and sub-group for the KPIs high accelerations ( = .176), conquered balls ( = .227) and attack balls ( = .146). Especially, U13MOhigh (i.e. early maturing players) faced a higher physiological challenge by having more high accelerations (|d| = 0.6) in BB games. Notably, U14MOlow (i.e. late maturing players) had more opportunities to show their technical-tactical abilities during BB games with more conquered balls (|d| = 1.1) and attack balls (|d| = 1.6). Affected KPIs indicate new challenges and learning opportunities during BB competition depending on a player’s individual maturity status. Bio-banding can beneficially be applied to enhance the talent development of youth elite soccer players.

Acute Effects of Intermittent Foot Cooling on 1 RM Leg Press Strength in Resistance-Trained Men: A Pilot Study.

Inter-set peripheral cooling can improve high-intensity resistance exercise performance. However, whether foot cooling (FC) would increase 1 repetition maximum (RM) lower-limb strength is unclear. This study investigated the effect of intermittent FC on 1 RM leg press strength. Ten recreational male lifters performed three attempts of 1 RM leg press with FC or non-cooling (NC) in a repeated-measures crossover design separated by 5 days. FC was applied by foot immersion in 10 °C water for 2.5 min before each attempt. During the 1 RM test, various physiological measures were recorded. The results showed that FC elicited higher 1 RM leg press strength (Δ [95% CI]; Cohen’s d effect size [ES]; 13.6 [7.6–19.5] kg; ES = 1.631) and electromyography values in vastus lateralis (57.7 [8.1–107.4] μV; ES = 0.831) and gastrocnemius (15.1 [−3.1–33.2] μV; ES = 0.593) than in NC. Higher arousal levels (felt arousal scale) were found in FC (0.6 [0.1–1.2]; ES = 0.457) than in NC. In conclusion, the preliminary findings, although limited, suggest intermittent FC has a potential ergogenic role for recreational athletes to enhance maximal lower-limb strength and may partly benefit strength-based competition events.