RESUMO
The regularity of the fluctuations present in torque signals represent the adaptability of the motor control. While previous research showed how it is affected by neuromuscular fatigue and ageing, the underlying mechanisms remain unclear. It is currently under debate whether these changes are explained by central or peripheral neuromuscular mechanisms. Here, we experimentally manipulated the sleep of thirteen young adults through a supervised 24 h-sleep deprivation protocol. This study aimed to investigate the effect of sleep deprivation on the regularity of torque fluctuations, and other standard torque-related outcomes (Peak Torque - PT - and Rate of Torque Development - RTD). The participants were asked to perform knee extension maximal voluntary contractions (MVC) and submaximal knee extensions at 40% of MVC for 30 s. PT and RTD were calculated from the MVC and the regularity of the torque fluctuations was determined on the submaximal task through Sample Entropy (SampEn). In addition, rate of perceived effort (RPE) was collected. We found no significant changes in PT and RTD. The regularity of torque fluctuations significantly increased (i.e., a decrease in SampEn) after 24 h-sleep deprivation (PRE = 1.76 ± 0.268, POS24 = 1.71 ± 0.306; p = 0.044). Importantly, we found a negative correlation between RPE and SampEn relative changes after sleep deprivation. This study brings new insights towards the understanding of the underlying mechanisms that explain changes in torque fluctuations, demonstrating that these changes are not limited to neuromuscular processes but are also likely to be affected by other domains, such as psychological profile, which can indirectly affect the neural drive to the muscles.
Assuntos
Contração Isométrica , Músculo Esquelético , Privação do Sono , Torque , Humanos , Masculino , Privação do Sono/fisiopatologia , Adulto Jovem , Adulto , Feminino , Músculo Esquelético/fisiologia , Contração Isométrica/fisiologia , Fadiga Muscular/fisiologia , EletromiografiaRESUMO
Speed is an essential skill in sports performance and an important performance metric in talent identification. This study aims to evaluate and compare the sprint acceleration characteristics across different age groups in an elite soccer academy. A total of 141 elite academy soccer players were recruited to participate in the study, and they were assigned to their respective competitive age groups, ranging from under-14 to the B-team. An individual in-situ acceleration-speed (A-S) profile was assessed and derived from Global Position System (GPS) speed-acceleration raw data, from 10 consecutive football sessions, in the beginning of the season. The results showed that under-14 players exhibited significantly lower theoretical maximum speed (S0) (ηp2 = 0.215, p < 0.01) when compared with all other age groups. However, no differences were found between maximum theoretical acceleration (A0) and A-S slope between age groups. The results suggest that sprint mechanical profiles of young soccer athletes remain stable throughout their athletic development. Nevertheless, younger athletes have less capacity to apply horizontal force at higher speeds (S0).
Assuntos
Desempenho Atlético , Corrida , Futebol , Humanos , Estudos Transversais , AceleraçãoRESUMO
The present study aimed to investigate the effects of a continuous visual feedback and the isometric contraction nature on the complexity and variability of force. Thirteen healthy and young male adults performed three MVCs followed by three submaximal isometric force tasks at a target force of 40% of their MVC for 30 s, as follows: (i) push isometric task with visual feedback (Pvisual); (ii) hold isometric task with visual feedback (Hvisual); (iii) hold isometric task without visual feedback (Hnon-visual). Force complexity was evaluated through sample entropy (SampEn) of the force output. Force variability was analyzed through the coefficient of variation (CV). Results showed that differences were task-related, with Pvisual showing higher complexity (i.e., higher SampEn) and decreased variability (i.e., lower CV) when compared with the remaining tasks. Additionally, no significant differences were found between the two hold isometric force tasks (i.e., no influence of visual feedback). Our results are promising as we showed these two isometric tasks to induce different motor control strategies. Furthermore, we demonstrated that visual feedback's influence is also dependent on the type of isometric task. These findings should motivate researchers and physiologists to shift training paradigms and incorporate different force control evaluation tasks.
Assuntos
Contração Isométrica , Músculo Esquelético , Masculino , Humanos , Contração Isométrica/fisiologia , Músculo Esquelético/fisiologia , Torque , Retroalimentação Sensorial , EntropiaRESUMO
ABSTRACT: Santos, PDG, Vaz, JR, Correia, J, Neto, T, and Pezarat-Correia, P. Long-term neurophysiological adaptations to strength training: a systematic review with cross-sectional studies. J Strength Cond Res 37(10): 2091-2105, 2023-Neuromuscular adaptations to strength training are an extensively studied topic in sports sciences. However, there is scarce information about how neural mechanisms during force production differ between trained and untrained individuals. The purpose of this systematic review is to better understand the differences between highly trained and untrained individuals to establish the long-term neural adaptations to strength training. Three databases were used for the article search (PubMed, Web of Science, and Scopus). Studies were included if they compared groups of resistance-trained with untrained people, aged 18-40 year, and acquired electromyography (EMG) signals during strength tasks. Twenty articles met the eligibility criteria. Generally, strength-trained individuals produced greater maximal voluntary activation, while reducing muscle activity in submaximal tasks, which may affect the acute response to strength training. These individuals also presented lower co-contraction of the antagonist muscles, although it depends on the specific training background. Global intermuscular coordination may be another important mechanism of adaptation in response to long-term strength training; however, further research is necessary to understand how it develops over time. Although these results should be carefully interpreted because of the great disparity of analyzed variables and methods of EMG processing, chronic neural adaptations seem to be decisive to greater force production. It is crucial to know the timings at which these adaptations stagnate and need to be stimulated with advanced training methods. Thus, training programs should be adapted to training status because the same stimulus in different training stages will lead to different responses.
Assuntos
Treinamento Resistido , Esportes , Humanos , Treinamento Resistido/métodos , Estudos Transversais , Eletromiografia , Adaptação Fisiológica/fisiologia , Músculo Esquelético/fisiologia , Força Muscular/fisiologiaRESUMO
Muscle coordination in human movement has been assessed through muscle synergy analysis. In sports science, this procedure has been mainly applied to the comparison between highly trained and unexperienced participants. However, the lack of knowledge regarding strength training exercises led us to study the differences in neural strategies to perform the power clean between weightlifters and untrained individuals. Synergies were extracted from electromyograms of 16 muscles of ten unexperienced participants and seven weightlifters. To evaluate differences, we determined the pairwise correlations for the synergy components and electromyographic profiles. While the shape of activation patterns presented strong correlations across participants of each group, the weightings of each muscle were more variable. The three extracted synergies were shifted in time with the unexperienced group anticipating synergy #1 (-2.46 ± 18.7%; p < 0.001) and #2 (-4.60 ± 5.71%; p < 0.001) and delaying synergy #3 (1.86 ± 17.39%; p = 0.01). Moreover, muscle vectors presented more inter-group variability, changing the composition of synergy #1 and #3. These results may indicate an adaptation in intermuscular coordination with training, and athletes in an initial phase of training should attempt to delay the hip extension (synergy #1), as well as the upper-limb flexion (synergy #2).
Assuntos
Músculo Esquelético , Esportes , Adaptação Fisiológica , Eletromiografia , Exercício Físico , HumanosRESUMO
Trunk modification is associated with knee abduction moment reduction in both healthy groups and individuals with knee osteoarthritis. Ambulatory-related changes in trunk kinematics have been implicated in increased trunk moment. The purpose of this study was to investigate the effect of dose-specific lateral trunk lean on trunk kinetics during ipsilateral and contralateral stance phases. Nineteen healthy participants completed 10 baseline walking trials, followed by 10 trials employing lateral trunk lean. Trunk modification magnitudes were determined based on the average baseline trunk angle. Five trials of both small and large trunk modification magnitudes were completed. Visual real-time biofeedback was projected as a line graph displaying the trunk angle during stance, and a highlighted bandwidth was designated the target range. A 1-factor repeated-measures analysis of variance or Friedman test was used to assess differences between the conditions (P < .05) in trunk dependent measures. Trunk kinetics displayed significant increases, even during modest modifications to the trunk angle. The participants experienced increased peak frontal plane trunk moment and angular impulse during ipsilateral stance. The observed increase in the peak lateral joint reaction force is suggestive of a compromised loading environment at the spine. Implementing trunk modification might result in unintended secondary changes along the kinetic chain, but further investigation is required.
Assuntos
Marcha , Osteoartrite do Joelho , Fenômenos Biomecânicos , Humanos , Cinética , Articulação do Joelho , Tronco , CaminhadaRESUMO
OBJECTIVES: Neurodynamic techniques are often used to treat people with sciatica pain, but their mechanical effects on the sciatic nerve are unknown. Shear wave elastography (SWE) has been shown to effectively estimate the stiffness of peripheral nerves in real time. The aim of this study was to use SWE to assess the effects of slump neurodynamics in the sciatic stiffness of people with sciatica. METHODS: Sixteen participants volunteered for this study. The sciatic stiffness of 8 patients with unilateral chronic sciatica and 8 healthy control participants was measured by SWE, with the participants in a prone position and during a dynamic condition (ie, ankle dorsiflexion). These measurements were performed before and immediately after the neurodynamic intervention, which consisted of a static slump position applied to the symptomatic limb of the patients with sciatica and in a randomly chosen limb of the healthy participants. RESULTS: The 8 patients with sciatica included 6 male and 2 female patients, and the 8 healthy control participants included 5 male and 3 female volunteers. Slump neurodynamics resulted in an immediate decrease in the sciatic nerve stiffness of the symptomatic limb in people with sciatica by 16.1% (effect size = 0.65; P = .019). The intervention showed no significant changes in the sciatic nerve stiffness of the healthy participants (effect size = 0.05; P = .754). CONCLUSIONS: Slump neurodynamics have the potential of decreasing the sciatic nerve stiffness in people with sciatica, and this effect can be quantified by SWE, which may provide valuable information for health professionals.
Assuntos
Técnicas de Imagem por Elasticidade/métodos , Manipulações Musculoesqueléticas/métodos , Ciática/diagnóstico por imagem , Ciática/terapia , Adulto , Feminino , Humanos , Masculino , Postura/fisiologia , Nervo Isquiático/diagnóstico por imagem , Nervo Isquiático/fisiopatologia , Ciática/fisiopatologia , Resultado do TratamentoRESUMO
This study examined whether professional footballers with previous biceps femoris long head (BFLH) injury in the last 3-years present a smaller proximal aponeurosis (Apo-BFLH) size compared to footballers with no previous injury. We examined the Apo-BFLH and BFLH size using magnetic resonance imaging and tested the knee flexor maximal isometric strength in 80 thighs of 40 footballers. Apo-BFLH size parameters were processed using a semi-automated procedure. Outcomes were compared between thighs with (n=9) vs. without (n=71) previous BFLH injury. No differences were observed between injured and non-injured thighs for the Apo-BFLH and BFLH size parameters (p>0.05) except for Apo-BFLH volume, which was higher in the non-injured thighs of athletes with previous injury (3692.1±2638.4 mm3, p<0.006) compared to the left (2274.1±798.7 mm3) thighs of athletes without previous injury. A higher knee flexor isometric strength was observed in the injured limb of athletes with previous BFLH injury (196.5±31.9 Nm, p<0.003) compared to the left (156.2±31.4 Nm) and right (160.0±31.4 Nm) thighs of non-injured athletes. The present results suggest that BFLH proximal aponeurosis size should not be considered as an independent risk factor for strain injury.
Assuntos
Aponeurose/anatomia & histologia , Músculos Isquiossurais/anatomia & histologia , Músculos Isquiossurais/lesões , Futebol/lesões , Futebol/fisiologia , Entorses e Distensões/epidemiologia , Adulto , Estudos Transversais , Músculos Isquiossurais/fisiologia , Humanos , Contração Isométrica , Masculino , Força Muscular/fisiologia , Fatores de Risco , Adulto JovemRESUMO
OBJECTIVES: The purpose of this study was to determine whether sciatic nerve stiffness is altered in people with chronic low back-related leg pain by using shear wave elastography. METHODS: In this cross-sectional study, the sciatic nerve shear wave velocity (ie, an index of stiffness) was measured in both legs of 16 participants (8 with unilateral low back-related leg pain and 8 healthy controls). Sciatic stiffness was measured during a passive ankle dorsiflexion motion performed at 2°/s in an isokinetic dynamometer. The ankle range of motion and passive torque, as well as muscle activity, were also measured. RESULTS: In people with low back-related leg pain, the affected limb showed higher sciatic nerve stiffness compared to the unaffected limb (+11.3%; P = .05). However, no differences were observed between the unaffected limb of people with low back-related leg pain and the healthy controls (P = .34). CONCLUSIONS: People with chronic low back-related leg pain have interlimb differences in sciatic nerve stiffness, as measured by a safe and noninvasive method: shear wave elastography. The changes found may be related to alterations in nerve mechanical properties, which should be confirmed by future investigations.
Assuntos
Técnicas de Imagem por Elasticidade/métodos , Dor Lombar/etiologia , Nervo Isquiático/diagnóstico por imagem , Nervo Isquiático/patologia , Neuropatia Ciática/diagnóstico por imagem , Neuropatia Ciática/patologia , Adolescente , Adulto , Dor Crônica/etiologia , Dor Crônica/fisiopatologia , Estudos Transversais , Eletromiografia , Feminino , Humanos , Perna (Membro)/fisiopatologia , Dor Lombar/fisiopatologia , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
PURPOSE: To assess the stiffness of hamstring muscles during isometric contractions in healthy individuals, using ultrasound-based shear wave elastography to (1) determine the intra- and inter-day assessment repeatability, (2) characterize the stiffness of semitendinosus (ST) and biceps femoris long head (BFlh) along the contraction intensity, and (3) characterize stiffness distribution among the hamstring muscles and inter-limb symmetry. METHODS: Two experiments were conducted. In experiment I (n = 12), the intra-day repeatability in assessing the BFlh and ST stiffness were determined at intensities between 10-60% of maximal voluntary isometric contraction (MVIC) in a single session. In experiment II (n = 11), the stiffness of the hamstring muscles of both thighs was assessed at 20% of MVIC in the first session; and retested (for one randomly chosen thigh) in a second session. Isometric contraction of knee flexors was performed with the knee flexed at 30° and with the hip in a neutral position. RESULTS: Moderate-to-very-high intra- and inter-day repeatability was found (ICC = 0.69-0.93). The BFlh/ST stiffness ratio increased with contraction intensity. At 20% of MVIC, the ST showed the highest stiffness among the hamstring muscles (p < 0.02), with no differences between the remaining hamstring muscles (p > 0.474). No differences were found between limbs (p = 0.12). CONCLUSIONS: The stiffness distribution among the hamstring muscles during submaximal isometric contractions is heterogeneous, but symmetric between limbs, and changes depending on the contraction intensity. Shear wave elastography is a reliable tool to assess the stiffness of hamstring muscles during contraction.
Assuntos
Músculos Isquiossurais/fisiologia , Contração Muscular/fisiologia , Adolescente , Adulto , Técnicas de Imagem por Elasticidade , Eletromiografia , Feminino , Humanos , Contração Isométrica/fisiologia , Articulação do Joelho/fisiologia , Masculino , Amplitude de Movimento Articular/fisiologia , Torque , Adulto JovemRESUMO
Two experiments (n = 10) were conducted to determine the effects of roller massager (RM) on ankle plantar flexor muscle recovery after exercise-induced muscle damage (EIMD). Experiment 1 examined both functional [i.e., ankle plantar flexion maximal isometric contraction and submaximal (30%) sustained force; ankle dorsiflexion maximal range of motion and resistance to stretch; and medial gastrocnemius pain pressure threshold] and morphological [cross-sectional area, thickness, fascicle length, and fascicle angle] variables, before and immediately, 1, 24, 48, and 72 h after an EIMD stimulus. Experiment 2 examined medial gastrocnemius deoxyhaemoglobin concentration kinetics before and 48 h after EIMD. Participants performed both experiments twice: with (RM) and without (no-roller massager; NRM) the application of a RM (6 × 45 s; 20-s rest between sets). RM intervention did not alter the functional impairment after EIMD, as well as the medial gastrocnemius morphology and oxygenation kinetics (P > 0.05). Although, an acute increase of ipsilateral (RM = + 19%, NRM = -5%, P = 0.032) and a strong tendency for contralateral (P = 0.095) medial gastrocnemius pain pressure threshold were observed. The present results suggest that a RM has no effect on plantar flexors performance, morphology, and oxygenation recovery after EIMD, except for muscle pain pressure threshold (i.e., a soreness).
Assuntos
Massagem/métodos , Músculo Esquelético/lesões , Mialgia/terapia , Traumatismos do Tornozelo/patologia , Traumatismos do Tornozelo/fisiopatologia , Traumatismos do Tornozelo/terapia , Articulação do Tornozelo/fisiopatologia , Feminino , Humanos , Contração Isométrica/fisiologia , Masculino , Massagem/instrumentação , Músculo Esquelético/diagnóstico por imagem , Músculo Esquelético/patologia , Músculo Esquelético/fisiopatologia , Mialgia/patologia , Mialgia/fisiopatologia , Consumo de Oxigênio , Limiar da Dor/fisiologia , Amplitude de Movimento Articular/fisiologia , Adulto JovemRESUMO
BACKGROUND: Modeling physiological signals is a complex task both for understanding and synthesize biomedical signals. We propose a deep neural network model that learns and synthesizes biosignals, validated by the morphological equivalence of the original ones. This research could lead the creation of novel algorithms for signal reconstruction in heavily noisy data and source detection in biomedical engineering field. METHOD: The present work explores the gated recurrent units (GRU) employed in the training of respiration (RESP), electromyograms (EMG) and electrocardiograms (ECG). Each signal is pre-processed, segmented and quantized in a specific number of classes, corresponding to the amplitude of each sample and fed to the model, which is composed by an embedded matrix, three GRU blocks and a softmax function. This network is trained by adjusting its internal parameters, acquiring the representation of the abstract notion of the next value based on the previous ones. The simulated signal was generated by forecasting a random value and re-feeding itself. RESULTS AND CONCLUSIONS: The resulting generated signals are similar with the morphological expression of the originals. During the learning process, after a set of iterations, the model starts to grasp the basic morphological characteristics of the signal and later their cyclic characteristics. After training, these models' prediction are closer to the signals that trained them, specially the RESP and ECG. This synthesis mechanism has shown relevant results that inspire the use to characterize signals from other physiological sources.
Assuntos
Redes Neurais de Computação , Processamento de Sinais Assistido por Computador , Eletrocardiografia , Eletromiografia , Respiração , Razão Sinal-RuídoRESUMO
The present study aimed to compare muscle coordination strategies of the upper and lower limb muscles between beginners and elite breaststroke swimmers. Surface electromyography (EMG) of eight muscles was recorded in 16 swimmers (8 elite, 8 beginners) during a 25 m swimming breaststroke at 100% of maximal effort. A decomposition algorithm was used to identify the muscle synergies that represent the temporal and spatial organisation of muscle coordination. Between-groups indices of similarity and lag times were calculated. Individual muscle patterns were moderately to highly similar between groups (between-group indices range: 0.61 to 0.84). Significant differences were found in terms of lag time for pectoralis major (P < 0.05), biceps brachii, rectus femoris and tibialis anterior (P < 0.01), indicating an earlier activation for these muscles in beginners compared to elites (range: -13.2 to -3.8% of the swimming cycle). Three muscle synergies were identified for both beginners and elites. Although their composition was similar between populations, the third synergy exhibited a high within-group variability. Moderate to high indices of similarity were found for the shape of synergy activation coefficients (range: 0.63 to 0.88) but there was a significant backward shift (-8.4% of the swimming cycle) in synergy #2 for beginners compared to elites. This time shift suggested differences in the global arm-to-leg coordination. These results indicate that the synergistic organisation of muscle coordination during breaststroke swimming is not profoundly affected by expertise. However, specific timing adjustments were observed between lower and upper limbs.
Assuntos
Braço , Perna (Membro) , Destreza Motora , Músculo Esquelético , Fenômenos Fisiológicos Musculoesqueléticos , Natação , Adolescente , Adulto , Atletas , Desempenho Atlético , Fenômenos Biomecânicos , Criança , Eletromiografia , Feminino , Humanos , Masculino , Adulto JovemRESUMO
This study aimed to develop a valid and reliable scale to assess the perception of stretching intensity below and above the maximal range of motion. Experiments were conducted through a passive leg extension angle-torque assessment to healthy population (n = 90). In the study's first phase, the visual, numerical, and description of the stretching intensity scale (SIS) components were developed. The visual analog scale (VAS) score, absolute magnitude estimation (AME) score, and verbal stretching intensity symptom descriptors were assessed for different stretching intensities. In the second phase, the SIS was tested for validity, reliability, scale production, and estimation properties as well as responsiveness to stretching. In the first phase, a high correlation was found between SIS score and range of motion (ROM), as well as SIS and torque in both submaximal (intraclass correlation coefficient [ICC] = 0.89-0.99, r = 0.88-0.99) and supramaximal (ICC = 0.75-0.86, r = 0.68-0.88) stretching intensities. The AME and VAS scores fitted well in an exponential model for submaximal stretching intensities (y = 14.829e, ICC = 0.97 [0.83-0.99], r = 0.98), and in a linear model for supramaximal stretching intensities (y = 0.7667x - 25.751, ICC = 0.97 [0.89-0.99], r = 0.9594). For the second phase, a high correlation was found between SIS score and ROM (r = 0.70-0.76, ICC = 0.76-0.85), as well as SIS and torque (r = 0.62-0.88, ICC = 0.57-0.85). The interday reliability was high to produce (r = 0.70, ICC = 0.70 [0.50-0.83]) or estimate (r = 0.89, ICC = 0.89 [0.82-0.93]) stretching intensities. The acute stretching effects on ROM and passive torque were detectable using the SIS. It is expected a high application in assessing the stretch intensity using the SIS in future studies and practical interventions.
Assuntos
Exercícios de Alongamento Muscular , Adulto , Eletromiografia , Humanos , Masculino , Músculo Esquelético/fisiologia , Amplitude de Movimento Articular/fisiologia , Reprodutibilidade dos Testes , Escala Visual Analógica , Adulto JovemRESUMO
OBJECTIVE: To analyze the influence of congested and noncongested fixture periods during 2 seasons in a professional male football team on soft-tissue injury incidence and external load. METHODS: Thirty-three professional football players from a Portuguese Liga I team participated in this study. Weekly external load and soft-tissue injury rate and burden of 2 consecutive seasons (2021-22 and 2022-23) were analyzed. RESULTS: Total soft-tissue injury rate and burden for the 2 seasons were 3.9 and 3.2 injuries per 1000 hours and 71.8 and 60.5 days per 1000 hours for congested and noncongested periods, respectively. No significant differences were observed between congested and noncongested periods. Total high-speed running, sprint distance, distance above 80% and 90% of maximal velocity, and meters accelerating and decelerating above 2 m/s2 were significantly higher for noncongested weeks. Match accelerations and decelerations above 3 m/s2 were higher during congested periods and training during noncongested periods. No differences between the 2 periods were observed for the total number of accelerations and decelerations above 3 m/s2. Overall, physical outputs per week were higher for training during noncongested weeks, whereas matches during congested periods registered higher external load. CONCLUSIONS: No effect of a congested schedule was observed on soft-tissue injury rates and injury burden. Higher match exposure during congested periods increased external load performed per week, and during noncongested periods, training load was superior to congested weeks.
RESUMO
Numerous cultural adaptations of the Tampa Scale of Kinesiophobia 11-item version (TSK-11) scale have emerged since the original version was introduced. We conducted a (COnsensus-based Standards for the selection of health Measurement INstruments) COSMIN-informed systematic review of measurement properties to identify the cross-cultural adaptation of the TSK-11 and report, critically appraise, and systematize its measurement properties. Six databases were searched for studies published since 2005. Studies reporting on the measurement properties of culturally adapted versions of the TSK-11, published in English, Portuguese, and Spanish, were considered for inclusion. The results were synthesized by measurement properties and rated against the COSMIN criteria for good measurement properties. The quality of the evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluation approach and presented in a summary of findings table. Twenty-three studies were included, and cultural adaptations for 15 languages were identified: English, Chinese, Cantonese, Swedish, German, Dutch, Arabic, Turkish, Danish, Spanish, Japanese, Brazilian Portuguese, Marathi, Thai, and Persian. There is "high" certainty in the evidence for "sufficient" criterion validity (TSK-17, r = .84) and "insufficient" measurement error (small detectable change range 5.6-6.16). "Moderate" certainty in the evidence for "sufficient" construct validity (87.8% of hypotheses confirmed), test-retest reliability (intraclass correlation coefficient2,1 = .747-.87), and "low" certainty in evidence for "sufficient" responsiveness. The numerous sources of heterogeneity prevent conclusions from being drawn regarding structural validity. Measurement error, responsiveness, and structural validity of the TSK-11 require further investigation. Clinicians should complement the use of TSK-11 with other instruments. Future studies on the structural validity of the questionnaire should standardize the data analysis methods. PERSPECTIVE: This article presents the measurement properties of the cross-cultural adaptations of the TSK-11. Clinicians should be aware that cultural and clinical aspects may influence the structural validity of the questionnaire. Using the TSK-11 as a stand-alone instrument may omit relevant clinical progression in the patient's condition.
RESUMO
Incorporating variability within gait retraining approaches has been proposed and shown to lead to positive changes. Specifically, submitting the individuals to walk in synchrony to cues that are temporally organized with a fractal-like patterns, promotes changes at the stride-to-stride fluctuations closer to those typically find in young adults. However, there is still a need to understand the underlying neuromuscular mechanisms associated to such improvement. Thus, this study aimed to investigate whether changes in the temporal structure of the variability in gait patterns are accompanied by changes in muscle activity patterns. Fourteen young individuals walked synchronized to one uncued (UNC) and three cued conditions: isochronous (ISO), fractal (FRC) and random (RND). Inter-stride intervals were determined from an accelerometer placed on the lateral malleoli. Inter-muscle peak intervals were obtained from the electromyographic signal from the gastrocnemius muscle. Fractal scaling, obtained through detrended fluctuation analysis, and coefficient of variation were calculated. Repeated measures ANOVAs were used to identify differences between conditions. Significant main effect was observed for both fractal scaling and coefficient of variation. Both shown no differences between UNC and FRC conditions, while ISO and RND were significantly lower compared to UNC and FRC conditions. In addition, a Pearson's Correlation was used to test the correlation between variables. A strong correlation was found the temporal structure of gait and muscle activity patterns. These findings strengthen the current literature regarding the incorporation of variability within cued approaches. Specifically, it shows that such an approach allows the modification of the neuromuscular processes underlying the stride-to-stride fluctuations.
Assuntos
Sinais (Psicologia) , Caminhada , Adulto Jovem , Humanos , Marcha/fisiologia , FractaisRESUMO
BACKGROUND: Each year, 1 in 4 people over the age of 65 years of age will experience a fall. It is important to identify and address modifiable risk factors that are associated with falls in adults at high and low risk for falls. HYPOTHESIS: Falls risk improves in both high-risk and low-risk participants with the implementation of Stay Active and Independent for Life (SAIL). STUDY DESIGN: Cohort study. LEVEL OF EVIDENCE: Level 3. METHODS: Seventy-eight older adults (age, 70.9 ± 5.1 years) were included in this study and categorized into high risk and low risk for falling based on the falls risk score from the Physiological Profile Assessment. High risk was defined as having a preintervention falls risk score >1, whereas low risk was defined as having a preintervention falls risk score <1. Both groups had the same 10-week intervention. A multivariate analysis of covariance was used to compare differences pre- and postintervention, using preintervention falls risk score as covariate. RESULTS: Results showed that regardless of preintervention falls risk, participants showed significant improvements in right and left knee extensor strength and sit-to-stand after participation in the 10-week SAIL program. Also, noteworthy is that 15 participants who were considered at high risk for falling preintervention were considered low risk for falling postintervention. CONCLUSION: The positive outcomes noted on modifiable risk factors suggest SAIL can be beneficial for decreasing falls risk in older adults, regardless of risk of falling, using a multifactorial exercise intervention. Our results also showed that it was possible for participants not only to improve falls risk but to improve to such a degree that they change from high risk to low risk of falling. CLINICAL RELEVANCE: Our results demonstrated that SAIL was effective in improving overall fall risk after a 10-week intervention. Targeted community-based interventions for the aging population can bring physical health benefits that can decrease falls risk.
Assuntos
Acidentes por Quedas , Terapia por Exercício , Humanos , Idoso , Acidentes por Quedas/prevenção & controle , Estudos de Coortes , Fatores de RiscoRESUMO
Although the underlying mechanisms behind upper limb (e.g., finger) motor slowing during movements performed at the maximum voluntary rate have been explored, the same cannot be said for the lower limb. This is especially relevant considering the lower limb's larger joints and different functional patterns. Despite the similar motor control base, previously found differences in movement patterns and segment inertia may lead to distinct central and peripheral manifestations of fatigue in larger joint movement. Therefore, we aimed to explore these manifestations in a fatiguing knee maximum movement rate task by measuring brain and muscle activity, as well as brain-muscle coupling using corticomuscular coherence, during this task. A significant decrease in knee movement rate up to half the task duration was observed. After an early peak, brain activity showed a generalized decrease during the first half of the task, followed by a plateau, whereas knee flexor muscle activity showed a continuous decline. A similar decline was also seen in corticomuscular coherence but for both flexor and extensor muscles. The electrophysiological manifestations associated with knee motor slowing therefore showed some common and some distinct aspects compared with smaller joint tasks. Both central and peripheral manifestations of fatigue were observed; the changes seen in both EEG and electromyographic (EMG) variables suggest that multiple mechanisms were involved in exercise regulation and fatigue development.NEW & NOTEWORTHY The loss of knee movement rate with acute fatigue induced by high-speed movement is associated with both central and peripheral electrophysiological changes, such as a decrease in EEG power, increased agonist-antagonist cocontraction, and impaired brain-muscle coupling. These findings had not previously been reported for the knee joint, which shows functional and physiological differences compared with the existing findings for smaller upper limb joints.