Quadriceps muscle reaction time in obese children.

This study aimed to determine the influence of obesity, according to body mass index (BMI) and fat mass percentage, on quadriceps muscle reaction times. The study utilized a cross-sectional design. The sample size consisted of 42 schoolchildren (54.5% girls) aged 11 to 12 years old. Participant measurements included weight and height, which were used to categorize individuals based on BMI. Additionally, the electrical bioimpedance technique was employed to categorize participants based on their body fat percentage. A sudden destabilization test of the lower limb was performed to assess the reaction time of the rectus femoris, vastus medialis, and vastus lateralis muscles. The results show that overweight/obese children have a longer muscle reaction time for both the rectus femoris (ß = 18.13; p = 0.048) and the vastus lateralis (ß = 14.51; p = 0.042). Likewise, when the children were classified by percentage of body fat the results showed that overfat/obese children have a longer muscle reaction time for both the rectus femoris (ß = 18.13; p = 0.048) and the vastus lateralis (ß = 14.51; p = 0.042). Our results indicate that BMI and fat mass classification negativity alter the muscle reaction time in children. Overweight/obese or overfat/obese children showed longer reaction times in the rectus femoris and vastus lateralis muscles compared to children with normal weight. Based on these findings, it is suggested that in overweight and obese children, efforts not only focus on reducing body weight but that be complemented with training and/or rehabilitation programs that focus on preserving the normal physiological function of the musculoskeletal system.

Enhanced muscle endurance through self-regulated dual-task exercises in elbow fracture rehabilitation: A cross-sectional study.

OBJECTIVE: The main objective of this study was to investigate the effect of a self-regulated dual task on muscle endurance within a single rehabilitation session in patients recovering from an elbow fracture. DESIGN: Cross-sectional study of individuals recovering from elbow fractures (N = 20). Muscle endurance was tested using elastic bands at Borg's CR10 intensity 3- during four conditions: single-task and dual-task for elbow flexion and extension. RESULTS: The cognitive condition significantly influenced muscle endurance (p < 0.001), while the type of elbow exercise (flexion or extension) did not significantly alter the results (p = 0.592). The perceived difficulty of the tasks showed a significant interaction effect (p = 0.032). The dual-task condition showed an average increase of about 15 repetitions. A moderate negative correlation was found between the differences in repetitions and the perceived difficulty of the flexion exercise (r = 0.677, p = 0.001). CONCLUSIONS: Dual-task with self-regulation enhances muscle endurance among patients recovering from an elbow fracture. However, the improvements appear to depend on the perceived difficulty of the cognitive task. Future randomized controlled trials are required to understand the therapeutic implications of dual-tasking.

Intra- and inter-rater reliability in ultrasonographic measurements of coracohumeral distance.

BACKGROUND: Ultrasonography (US) is a widely used diagnostic tool in physical therapy. One of the US variables often utilized to quantify the dimensions of the subacromial space and its association with shoulder pathology is the coracohumeral distance (CHD), however, this measurement presents diverse evidence in terms of reliability. OBJECTIVES: To assess the intra- and inter-rater reliability of both expert and non-expert raters when measuring CHD through US in asymptomatic subjects. Additionally, we determined the effect of rater experience and measurement conditions on the recording of CHD. METHODS: CHD of 15 individuals were recorded from US images of the glenohumeral joint of both upper extremities in three different positions. An expert and a non-expert rater in US usage recorded three CHD measurements, after a randomization procedure. To determine intra- and inter-rater reliability, the interclass correlation coefficient (ICC) and a multivariate variance model for the effects of rater experience, joint position and time of measure were used. Standard Error of Measurement and Minimal Detectable Change was also estimated for CHD measurements. RESULTS: Intra-rater reliability ranged 0.970 to 0.998) and Inter-rater reliability ranged 0.48 to 0.876). Joint position (F2;55 = 38.308; p < 0.001; ηp2 = 0.582) and measurement time (F2;55 = 6.019; p = 0.004; ηp2 = 0.180) effect was observed on CHD. CONCLUSION: Excellent intra- and poor to moderate inter-rater reliability between expert and non-expert clinicians was determined, the latter being influenced by the position of the glenohumeral joint position at the time of US recording and the time of recording the measurement.

Effects of dominance and vision on unipedal balance tests in futsal players using a triaxial accelerometer.

Optimal postural control improves performance and reduces the risk of injury in futsal. In this context, wearable accelerometers may detect velocity changes of the centre of mass during a task, enabling the analysis of postural control in different environments. This work aimed to determine the influence of vision and dominance on unipodal static postural balance in non-professional athletes. Twenty-four university male futsal players performed a unipodal balance test to assess their body sway using a triaxial accelerometer. To assess dominance, the preferred limb for kicking the ball was considered, while vision was manipulated by asking participants to close their eyes during the test. Root mean square (RMS) and sample entropy (SaEn) of centre of mass variables were analysed. For statistical analysis, a multivariate analysis of variance model was used. Our results suggest an effect of vision, but not of dominance nor the interaction between vision and limb dominance. Specifically, a higher-acceleration RMS in the mediolateral axis was observed, as well as an increased SaEn in the three axes. To conclude, unipodal postural demand in futsal players under visual input suppression was not influenced by their limb dominancy.

A comparative electromyographic study of scapular stabilizing muscles during five main rehabilitation exercises.

OBJECTIVE: To compare the surface electromyographic (sEMG) amplitude, activation ratio, and onset latency of the main scapular stabilizing muscles between five typical rehabilitative exercises. DESIGN: Twenty-seven healthy participants performed five scapular exercises [wall-slide (WS), wall push-up plus, prone horizontal abduction with external rotation (PHABER), external rotation in side-lying (ERSL), and low row] while simultaneously recording sEMG of serratus anterior (SA), middle trapezius (MT), lower trapezius (LT), and upper trapezius (UT). sEMG amplitudes, onset latencies, and activation ratios were calculated. RESULTS: PHABER showed an excellent UT/MT (0.43) and UT/LT (0.30) muscle balance with high (> 50% MVIC) MT and LT amplitudes, a low (< 20% MVIC) UT amplitude, and an early activation of the scapular stabilizing muscles (-474.7 to 89.9 ms) relative to UT. ERSL showed excellent UT/SA (0.26), UT/MT (0.32), and UT/LT (0.21) activation ratios; and along with LR and WS, showed early activation of the scapular stabilizing muscles (-378.1 to -26.6 ms). CONCLUSIONS: PHABER presented optimal scapular neuromuscular control. Although ERSL, low row, and WS did not meet all the criteria associated with optimal scapular neuromuscular control, these exercises could be used in early stages of shoulder rehabilitation because they favor early activation of the scapular stabilizing muscles.

Individuals with chronic ankle instability show altered regional activation of the peroneus longus muscle during ankle eversion.

Individuals with chronic ankle instability (CAI) present muscular weakness and potential changes in the activation of the peroneus longus muscle, which likely explains the high recurrence of ankle sprains in this population. However, there is conflicting evidence regarding the role of the peroneus longus activity in CAI, possibly due to the limited spatial resolution of the surface electromyography (sEMG) methods (i.e., bipolar sEMG). Recent studies employing high-density sEMG (HD-sEMG) have shown that the peroneus longus presents differences in regional activation, however, it is unknown whether this regional activation is maintained under pathological conditions such as CAI. This study aimed to compare the myoelectric activity, using HD-sEMG, of each peroneus longus compartment (anterior and posterior) between individuals with and without CAI. Eighteen healthy individuals (No-CAI group) and 18 individuals with CAI were recruited. In both groups, the center of mass (COM) and the sEMG amplitude at each compartment were recorded during ankle eversion at different force levels. For the posterior compartment, the sEMG amplitude of CAI group was significantly lower than the No-CAI group (mean difference = 5.6% RMS; 95% CI = 3.4-7.6; p = 0.0001). In addition, it was observed a significant main effect for group (F1,32 = 9.608; p = 0.0040) with an anterior displacement of COM for the CAI group. These findings suggest that CAI alters the regional distribution of muscle activity of the peroneus longus during ankle eversion. In practice, altered regional activation may impact strengthening programs, prevention, and rehabilitation of CAI.

The optimal dose of pain neuroscience education added to an exercise programme for patients with chronic spinal pain: A systematic review and dose-response meta-analysis.

ABSTRACT: Pain neuroscience education (PNE) has shown promising results in the management of patients with chronic spinal pain (CSP). However, no previous review has determined the optimal dose of PNE added to an exercise programme to achieve clinically relevant improvements. The aim was to determine the dose-response association between PNE added to an exercise programme and improvements in pain intensity and disability in patients with CSP. A systematic search of PubMed/MEDLINE, Embase, Web of Science, Scopus, and the Cochrane Library was conducted from inception to April 19, 2023. The exposure variable (dosage) was the total minutes of PNE. Outcome measures included pain intensity, disability, quality of life, pressure pain thresholds, and central sensitization inventory. Data extraction, risk-of-bias assessment, and certainty of evidence were performed by 2 independent reviewers. The dose-response relationship was assessed using a restricted cubic spline model. Twenty-six randomised controlled trials with 1852 patients were included. Meta-analysis revealed a statistically significant effect in favour of PNE on pain intensity and disability. In addition, a dose of 200 and 150 minutes of PNE added to an exercise programme was estimated to exceed the minimum clinically important difference described in the literature for pain intensity (-2.61 points, 95% CI = -3.12 to -2.10) and disability (-6.84 points, 95% CI = -7.98 to -5.70), respectively. The pooled effect of the isolated exercise was small. These findings may be useful in optimising the most appropriate PNE dose to achieve clinically relevant improvements in patients with CSP.

A scoping review of tendon transfer surgeries and postsurgical physical therapy interventions in individuals with massive rotator cuff tears.

OBJECTIVE: To identify tendon transfer surgeries and postsurgical physical therapy interventions in people with massive rotator cuff (RC) tears. METHODS: The literature search was conducted in the MEDLINE, Science Direct, Scopus, Web of Science, and PEDro databases from inception to September 2022. Studies with patients diagnosed with massive RC tears undergoing tendon transfers that reported physical therapy interventions after surgery were included. Two reviewers pooled the data into ad hoc summary tables with the following information: authors, year, study characteristics (sample size, tendon transfer surgical used, approach type, preoperative risk, deficit addressed, additional surgical interventions), and physical therapy interventions (early stage, intermediate stage, and advanced stage). RESULTS: Forty-four articles (59.0% case series) were included, with a total sample of 1213 participants. The most frequently used surgery was the isolated tendon transfer of the latissimus dorsi (49.1%). Most of the studies reported three main stages of physical therapy interventions after tendon transfer surgery: early stage (lasting 5-6 weeks), intermediate stage (started at 7-12 weeks), and advanced stage (started at 12 weeks). Physical therapy interventions included passive, active-assisted, resisted therapeutic exercise, and hydrotherapy. CONCLUSIONS: The evidence regarding physical therapy interventions after RC tendon transfer surgery is limited to the number and duration of the stages and general characteristics without specifying the type and dose of the interventions. Future research with high methodological quality should integrate more detailed rehabilitation protocols to better guide therapeutic decisions after RC transfer surgery.

Structural Brain Alterations in Individuals Post-COVID-19: A Systematic Review / Alteraciones Estructurales Cerebrales en Individuos Post COVID-19: Una Revisión Sistemática

SUMMARY: Although COVID-19 is primarily considered a respiratory pathology, it has been observed to impact other bodily systems, including the nervous system. While several studies have investigated anatomical changes in brain structures, such as volume or thickness post-COVID-19, there are no comprehensive reviews of these changes using imaging techniques for a holistic understanding. The aim of this study was to systematically analyze the literature on brain changes observed through neuroimaging after COVID-19. We conducted a systematic review according to PRISMA guidelines using Web of Science, Scopus, Medline, Pubmed, Sciencedirect, and LitCOVID. We selected studies that included adult patients during or after COVID-19 development, a control group or pre-infection images, and morphometric measurements using neuroimaging. We used the MSQ scale to extract information on sample characteristics, measured anatomical structures, imaging technique, main results, and methodological quality for each study. Out of 1126 identified articles, we included 19 in the review, encompassing 1155 cases and 1284 controls. The results of these studies indicated a lower volume of the olfactory bulb and variable increases or decreases in cortical and limbic structures' volumes and thicknesses. Studies suggest that brain changes occur post-COVID-19, primarily characterized by a smaller olfactory bulb. Additionally, there may be variations in cortical and limbic volumes and thicknesses due to inflammation or neuroplasticity, but these findings are not definitive. These differences may be attributed to methodological, geographical, and temporal variations between studies. Thus, additional studies are required to provide a more comprehensive and quantitative view of the evidence.

Aunque el COVID-19 se considera principalmente una patología respiratoria, se ha observado que afecta otros sistemas corporales, incluido el sistema nervioso. Si bien varios estudios han investigado los cambios anatómicos en las estructuras cerebrales, como el volumen o el grosor posteriores a la COVID-19, no hay revisiones exhaustivas de estos cambios que utilicen técnicas de imágenes para una comprensión holística. El objetivo de este estudio fue analizar sistemáticamente la literature sobre los cambios cerebrales observados a través de neuroimagen después de COVID-19. Realizamos una revisión sistemática de acuerdo con las pautas PRISMA utilizando Web of Science, Scopus, Medline, Pubmed, Sciencedirect y LitCOVID. Seleccionamos estudios que incluyeron pacientes adultos durante o después del desarrollo de COVID-19, un grupo de control o imágenes previas a la infección y mediciones morfométricas mediante neuroimagen. Utilizamos la escala MSQ para extraer información sobre las características de la muestra, las estructuras anatómicas medidas, la técnica de imagen, los principales resultados y la calidad metodológica de cada estudio. De 1126 artículos identificados, incluimos 19 en la revisión, que abarca 1155 casos y 1284 controles. Los resultados de estos estudios indicaron un menor volumen del bulbo olfatorio y aumentos o disminuciones variables en los volúmenes y espesores de las estructuras corticales y límbicas. Los estudios sugieren que los cambios cerebrales ocurren después del COVID-19, caracterizados principalmente por un bulbo olfatorio más pequeño. Además, pueden haber variaciones en los volúmenes y grosores corticales y límbicos debido a la inflamación o la neuroplasticidad, pero estos hallazgos no son definitivos. Estas diferencias pueden atribuirse a variaciones metodológicas, geográficas y temporales entre estudios. Por lo tanto, se requieren estudios adicionales para proporcionar una visión más completa y cuantitativa de la evidencia.

Structural and functional brain changes in people with knee osteoarthritis: a scoping review.

Background: Knee osteoarthritis is a highly prevalent disease worldwide that leads to functional disability and chronic pain. It has been shown that not only changes are generated at the joint level in these individuals, but also neuroplastic changes are produced in different brain areas, especially in those areas related to pain perception, therefore, the objective of this research was to identify and compare the structural and functional brain changes in knee OA versus healthy subjects. Methodology: Searches in MEDLINE (PubMed), EMBASE, WOS, CINAHL, SCOPUS, Health Source, and Epistemonikos databases were conducted to explore the available evidence on the structural and functional brain changes occurring in people with knee OA. Data were recorded on study characteristics, participant characteristics, and brain assessment techniques. The methodological quality of the studies was analysed with Newcastle Ottawa Scale. Results: Sixteen studies met the inclusion criteria. A decrease volume of the gray matter in the insular region, parietal lobe, cingulate cortex, hippocampus, visual cortex, temporal lobe, prefrontal cortex, and basal ganglia was found in people with knee OA. However, the opposite occurred in the frontal lobe, nucleus accumbens, amygdala region and somatosensory cortex, where an increase in the gray matter volume was evidenced. Moreover, a decreased connectivity to the frontal lobe from the insula, cingulate cortex, parietal, and temporal areas, and an increase in connectivity from the insula to the prefrontal cortex, subcallosal area, and temporal lobe was shown. Conclusion: All these findings are suggestive of neuroplastic changes affecting the pain matrix in people with knee OA.

Influence of lower limb muscle isometric strength and cardiovascular parameters on locomotor capacity in children and adolescents.

BACKGROUND: Although measures of exercise performance and physical activity are known to be related to 6-minute walk test (6mWT), the role of the strength of each muscle group of the lower limb in the locomotor capacity during the development period is unknown. OBJECTIVE: To identify the role of the isometric strength of lower limb muscles and cardiovascular parameters on the locomotor capacity in children and adolescents, controlling for participants sex, age, and height. METHODS: Participants (7 to 15 years old; female, n= 113; male, n= 128) were assessed for isometric strength (seven lower limb muscles), cardiovascular parameters (diastolic pressure, oxygen saturation, resting heart rate, respiratory rate), and 6mWT. Participants were split into nine age groups and separated by 1-year intervals. RESULTS: Hip flexors-controlled for sex, age, and height-explained a meaningful percentage of the variance (R=2 0.45; p< 0.001) for 6mWT distance, and the resting heart rate explained a change in R2 of only 2% (p= 0.008). CONCLUSIONS: Isometric strength of hip flexors explained ∼ 50% of the 6mWT distance, suggesting the importance of strength from an early age. Other factors, such as cardiovascular parameters, while relevant, may exert a secondary role on youth's capacity.

Dosage matters: Uncovering the optimal duration of pain neuroscience education to improve psychosocial variables in chronic musculoskeletal pain. A systematic review and meta-analysis with moderator analysis.

The aim was to examine the moderator effect of duration of PNE (total minutes) on changes in psychosocial variables after treatment in people with chronic musculoskeletal pain. PubMed/MEDLINE, Embase, Web of Science, Scopus and CINHAL databases were systematically searched from inception to 6 February 2023. A mixed-effects meta-regression was performed to determine the moderator effect of PNE duration. Twenty-three studies involving 2352 patients were included. Meta-analysis revealed a statistically significant effect in favour of PNE on pain neurophysiology knowledge, anxiety symptoms, catastrophizing and kinesiophobia. The total duration of PNE ranged from 40 to 720 min. A linear relationship was observed between longer duration of PNE (total minutes) and changes of psychosocial variables. In addition, a dose of 100, 200 and 400 min of PNE was estimated to exceed the minimum clinically important difference described in the literature for kinesiophobia (mean difference = -8.53 points), anxiety symptoms (mean difference = -1.88 points) and catastrophizing (mean difference = -7.17 points). Clinicians should provide a more tailored PNE to address psychosocial variables.

Barriers and facilitators of physical activity in adults with severe haemophilia: A qualitative study.

BACKGROUND: People with haemophilia (PWH) tend to be less physically active than the general population, but there is a lack of research on the specific barriers and facilitators affecting their participation in physical activities. OBJECTIVES: This study aims to explore perceived barriers and facilitators to physical activity in severe PWH. DESIGN: An explorative qualitative study based on focus groups. METHODS: Four focus groups including 16 participants (severe haemophilia A patients) were conducted to examine the factors perceived as facilitators or barriers to haemophiliacs engaging in physical activity. One researcher conducted a thematic analysis of all data. RESULTS: Three themes were identified: body function, personal factors, and environmental factors. Key facilitators identified were access to prophylaxis treatment to reduce the risk of bleeding(s), the enjoyability of physical activity, fitness and health motives, social interaction, support, and low cost. PWH faced additional barriers to being physically active including hurtful joints, mobility issues, haemophilic arthropathy, dislike or disinterest, lack of motivation, fear of injury, tiredness, lack of time, lack of guidance, negative social influence, restriction, and lack of coordination of prophylaxis treatment. CONCLUSION: This exploratory study demonstrated that participation in physical activity in PWH is influenced not only by their own abilities and attitudes, but also by external variables, including family, friends, healthcare professionals, structures, and communities. The results of this study may be used to assist caregivers and health professionals, inform programs, interventions, and policies to promote physical activity and health in severe PWH.

Task-related differences in peroneus longus muscle fiber conduction velocity.

It has been identified that the peroneus longus presents a regional activity. Specifically, a greater activation of the anterior and posterior compartments has been observed during eversion, whereas a lower activation of the posterior compartment has been reported during plantarflexion. In addition to myoelectrical amplitude, motor unit recruitment can be inferred indirectly from muscle fiber conduction velocity (MFCV). However, there are few reports of MFCV of the regions that make up a muscle, and even less, MFCV of the peroneus longus compartments. This study aimed to analyze the MFCV of peroneus longus compartments during eversion and plantarflexion. Twenty-one healthy individuals were assessed. High-density surface electromyography was recorded from the peroneus longus during eversion and plantarflexion at 10%, 30%, 50%, and 70% of maximal voluntary isometric contraction. The posterior compartment presented a lower MFCV than the anterior compartment during plantarflexion, and both compartments did not show differences in MFCV during eversion; however, the posterior compartment showed an increase in MFCV during eversion compared to plantarflexion. Differences observed in the MFCV of the peroneus longus compartments could support a regional activation strategy and, to some extent, explain different motor unit recruitment strategies of the peroneus longus during ankle movements.

Gender differences on effects of forearm rotation on compressive stiffness of flexor carpi ulnaris during submaximal handgrip contractions.

Little is known about gender differences in stiffness of forearm muscles during voluntary actions. This study aimed to investigate the effect of forearm rotation on flexor carpi ulnaris (FCU) stiffness in men and women during submaximal handgrip contractions. During a single session, measurements were made on 20 young participants (9 females). Two positions of the forearm were compared in random order with the elbow flexed 90 degrees: (i) neutral position and (ii) maximal supination. In each position, participants performed two submaximal handgrip contractions at 25% and 50% of maximal voluntary contraction, while compressive stiffness was collected using a hand myometer (MyotonPRO). A mixed repeated measurement ANOVA was applied to assess the interaction between gender, forearm position, and contraction intensity. The FCU stiffness is affected by handgrip contraction intensity (p < 0.001), gender (p < 0.001), BMI (p = 0.009), and forearm rotation (p = 0.007). Only the gender factor was found to have significant interaction with forearm rotation (p = 0.037). Men's FCU was stiffer than women's in both positions and contraction intensities (p < 0.05). Only in men a significant increase in FCU stiffness was observed when comparing contraction intensities at both forearm positions (p < 0.05), as well as when the forearm was rotated from neutral to supine at both intensities (p < 0.05). In conclusion, FCU stiffness during handgrip contraction differed significantly between men and women. Women have fewer stiffness changes in FCU when performing different levels of handgrip contraction. We also observed that only men increased FCU stiffness by changing the forearm position from neutral to supine position for both handgrip intensities.

Exercise variables and pain threshold reporting for strength training protocols in people with haemophilia: A systematic review of clinical trials.

INTRODUCTION: Although strength exercise is often prescribed for people with haemophilia (PWH), it remains unknown how exercise variables and pain thresholds are used to prescribe strength training in PWH. AIM: To analyse how strength exercise variables and pain thresholds have been used to prescribe strength training in PWH. METHODS: A systematic search was conducted in PubMed, Embase, Web of Science, CENTRAL and CINAHL databases from inception to 7 September 2022. Studies whose intervention included strengthening training in adults with haemophilia were included. Two independent reviewers were involved in study selection, data extraction and risk of bias assessment. RESULTS: Eighteen studies were included. The least reported variables among the studies were: prophylactic factor coverage (11.1%), pain threshold/tolerability (5.6%), intensity (50%), total or partial range of motion (27.8%), time under tension (27.8%), attentional focus modality (0%), therapist experience in haemophilia (33.3%) and adherence assessment (50%). In contrast, weekly frequency (94.4%), duration (weeks) (100%), number of sets/repetitions (88.9%), repetitions to failure/not to failure (77.8%), types of contraction (77.8%), rest duration (55.6%), progression (55.6%), supervision (77.8%), exercise equipment (72.2%) and adverse event record (77.8%) had a higher percentage of reported (>50% of studies). CONCLUSION: Future research on strength training for PWH should improve information on pain threshold and other important variables such as prophylactic factor coverage, intensity, range of motion, time under tension, attentional focus modality, therapist experience in haemophilia and adherence assessment. This could improve clinical practice and comparison of different protocols.

Anthropometric Profile and Physical Activity Level as Predictors of Postural Balance in Overweight and Obese Children.

Overweightness and obesity can negatively influence many activities, including postural balance and locomotion, increasing predisposition to injury and risk of falls due to limitations on the biomechanics of daily living. The present study aimed to determine the influence of the anthropometric profile and physical activity level (PAL) on the postural balance of overweight and obese children. The sample included 387 schoolchildren (216 boys and 171 girls). The variables of the anthropometric profile studied were body mass, biped height, BMI, waist circumference, waist-to-hip ratio (WHR), summation of folds, body composition, and somatotype. PAL was measured using the PAQ-C questionnaire. Static and dynamic postural balance were measured through an open-eye (OE) and closed-eye (CE) posturographic test and the SEBTm, respectively. For static balance, the significant models were for mediolateral velocity (R2 = 0.42 in OA; R2 = 0.24 in OC), anteroposterior velocity (R2 = 0.21 in OA; R2 = 0.27 in OC), and mean velocity (R2 = 0.27 in OA; R2 = 0.46 in OC), where the predictors of low performance were younger age, male sex, overweight/obese nutritional status, greater thickness of skin folds, less tendency to mesomorphy, and greater fat mass. On the other hand, for dynamic postural balance, the significant models were observed in the previous direction (R2 = 0.39), posteromedial (R2 = 0.57), and posterolateral (R2 = 0.56), where the variables that predict a low performance were low PAL, overweight/obese nutritional status, and high WHR. Overweight and obese children presented a deficit in static and dynamic postural balance, enhanced by variables such as gender, age, PAL, and anthropometric characteristics related to adiposity.

Soleus muscle and Achilles tendon compressive stiffness is related to knee and ankle positioning.

Changes in fascicle length and tension of the soleus (SOL) muscle have been observed in humans using B-mode ultrasound to examine the knee from different angles. An alternative technique of assessing muscle and tendon stiffness is myometry, which is non-invasive, accessible, and easy to use. This study aimed to estimate the compressive stiffness of the distal SOL and Achilles tendon (AT) using myometry in various knee and ankle joint positions. Twenty-six healthy young males were recruited. The Myoton-PRO device was used to measure the compressive stiffness of the distal SOL and AT in the dominant leg. The knee was measured in two positions (90° of flexion and 0° of flexion) and the ankle joint in three positions (10° of dorsiflexion, neutral position, and 30° of plantar flexion) in random order. A three-way repeated-measures ANOVA test was performed. Significant interactions were found for structure × ankle position, structure × knee position, and structure × ankle position × knee position (p < 0.05). The AT and SOL showed significant increases in compressive stiffness with knee extension over knee flexion for all tested ankle positions (p < 0.05). Changes in stiffness relating to knee positioning were larger in the SOL than in the AT (p < 0.05). These results indicate that knee extension increases the compressive stiffness of the distal SOL and AT under various ankle joint positions, with a greater degree of change observed for the SOL. This study highlights the relevance of knee position in passive stiffness of the SOL and AT.

Isometric strength of upper limb muscles in youth using hand-held and hand-grip dynamometry.

The present study aimed to determine the isometric strength profile of the upper limb muscles of children and adolescents between 7-15 years of age. Furthermore, to (a) identify the age at which differences in strength are observed between sexes; to (b) determine the age range at which significant progression of strength could be observed; and (c) identify the role of each muscle on the total upper limb strength. Cross-sectional study that evaluated the isometric strength of nine muscle groups of the upper limb of 243 Chilean children, split into 9 age groups, separated by 1-year intervals. For this, hand-held dynamometry and hand-grip dynamometry were used. A two-factor analysis of variance for the maximum isometric strength and a stepwise multiple linear regression analysis were performed. From 11 years of age, wrist flexors were the first muscle group that revealed a significant difference in isometric strength in favor of boys (P=0.0143). In boys, the narrowest and earliest age range in the progression of isometric strength was 10 to 12 years for wrist flexors (P=0.0392). Shoulder flexors was the main factor that explained the performance of the total upper limb strength (R 2=0.742; P<0.001). The most progressive isometric strength development occurred from age 10 years in the ventral and distal muscles of the upper limb; and from this age the boys begin to present a greater isometric strength than girls. In addition, the isometric strength of shoulder flexors explained the higher total upper limb strength performance.

Electromyographic analysis of the serratus anterior and upper trapezius in closed kinetic chain exercises performed on different unstable support surfaces: a systematic review and meta-analysis.

Background: Multiple investigations have compared the electromyographic (EMG) activity of the scapular muscles between stable and unstable support surfaces during the execution of closed kinetic chain exercises. However, these comparative analyses have grouped different unstable surfaces (wobble board, BOSU, therapeutic ball, and suspension equipment) into a single data pool, without considering the possible differences in neuromuscular demand induced by each unstable support surface. This study aimed to analyze the individual effect of different unstable support surfaces compared to a stable support surface on scapular muscles EMG activity during the execution of closed kinetic chain exercises. Methodology: A literature search was conducted of the Pubmed Central, ScienceDirect and SPORTDiscus databases. Studies which investigated scapular muscles EMG during push-ups and compared at least two support surfaces were included. The risk of bias of included articles was assessed using a standardized quality assessment form for descriptive, observational and EMG studies, and the certainty of the evidence was measured with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. A random-effects model was used to calculate effect sizes (ES, Hedge's g). Results: Thirty studies were selected in the systematic review. Of these, twenty-three low-to-high quality studies (498 participants) were included in the meta-analysis. The main analyzes revealed, in decreasing order, greater UT EMG activity during push-ups performed on suspension equipment (ES = 2.92; p = 0.004), therapeutic ball (ES = 1.03; p < 0.001) and wobble board (ES = 0.33; p = 0.003); without effect on the BOSU ball. In addition, no effect was observed for SA on any unstable device. The certainty of the evidence ranged from low to very low due to the inclusion of descriptive studies, as well as high imprecision, inconsistency, and risk of publication bias. Conclusion: These findings could be applied in scapular muscles strengthening in healthy individuals. The use of suspension equipment achieves higher UT activation levels. Conversely, the use of any type of unstable devices to increase the activation levels of the SA in shoulder musculoskeletal dysfunctions is not recommended. These conclusions should be interpreted with caution as the available evidence showed a low to very low certainty of evidence, downgraded mostly by inconsistency and imprecision.