Aging effects of haptic input on postural control under a dual-task paradigm.

Postural control relies on three principal sensory systems: vision, vestibular and proprioceptive; that are affected by aging. When performing a cognitive task concomitantly with a motor task, those sensory impairments lead to even greater deleterious effects on balance. We aimed to study the effects of a sensory aid (a light touch) on a dual task paradigm and sought to understand the different responses on balance due to aging. Fifty healthy and highly physical active women were divided in two groups: young (N = 25, 24.2 ± 4.0 years) and older adults (N = 25, 67.3 ± 4.2 years). In a random and balanced order, all participants performed five tasks: Stroop test while seated (Seated); Stroop test while standing quiet (ST); Standing quiet (BL); Standing quiet with a haptic input (LT); and Stroop test with a haptic input while standing quiet (SL). In the Stroop test, older women committed more errors (50 vs 11 errors, p < 0.001) and had higher reaction time (1.001 ± 0.191 vs 0.699 ± 0.081 s, p < 0.001). The haptic input (LT) reduced all body sway parameters, in both groups, regardless the condition. This means that postural control under a dual task paradigm (ST) deleterious effect can be mitigated by a haptic input.

Eccentric Strength Assessment of Hamstring Muscles with New Technologies: a Systematic Review of Current Methods and Clinical Implications.

BACKGROUND: Given the severe economic and performance implications of hamstring injuries, there are different attempts to identify their risk factors for subsequently developing injury prevention strategies to reduce the risk of these injuries. One of the strategies reported in the scientific literature is the application of interventions with eccentric exercises. To verify the effectiveness of these interventions, different eccentric strength measurements have been used with low-cost devices as alternatives to the widespread used isokinetic dynamometers and the technically limited handheld dynamometers. Therefore, the purpose of the present systematic review was to summarize the findings of the scientific literature related to the evaluation of eccentric strength of hamstring muscles with these new technologies. METHODS: Systematic searches through the PubMed, Scopus, and Web of Science databases, from inception up to April 2020, were conducted for peer reviewed articles written in English, reporting eccentric strength of hamstrings assessed by devices, different to isokinetic and handheld dynamometers, in athletes. RESULTS: Seventeen studies were finally included in the review with 4 different devices used and 18 parameters identified. The pooled sample consisted of 2893 participants (97% male and 3% female: 22 ± 4 years). The parameters most used were peak force (highest and average), peak torque (average and highest), and between-limb imbalance (left-to-right limb ratio). There is inconsistency regarding the association between eccentric hamstrings strength and both injury risk and athletic performance. There is no standardized definition or standardization of the calculation of the used parameters. CONCLUSIONS: The current evidence is insufficient to recommend a practical guide for sports professionals to use these new technologies in their daily routine, due to the need for standardized definitions and calculations. Furthermore, more studies with female athletes are warranted. Despite these limitations, the eccentric strength of hamstring muscles assessed by different devices may be recommended for monitoring the neuromuscular status of athletes.

Perception of impact is affected by stimulus intensity.

Perception of external loads may be a central topic to understand adjustments to the mechanical demands during movement. Nevertheless, the association between the perceived and the real load received is still controversial. This study aimed to correlate vertical ground reaction force (vGRF) to the perception of impact in different regimens of stimulus application. Ten physically active men performed drop jumps from four different heights (0.20, 0.40, 0.60 and 0.80 m). A force plate measured the vGRF, while perception of impact was evaluated through Borg's Ratings of Perceived Exertion. Higher values of maximum vGRF (Fy_max) and impulse of the first 50 ms (I_50), and reduced time to reach Fy_max indicate increased external forces as drop jump height raised. Perception of impact increased gradually with increasing jump height for I_50. Fy_max and I_50 showed moderate to strong correlations to perceived load for 70% and 90% of participants, respectively. Higher and different intensity of stimulus facilitated the perception of impact, presenting moderate to strong correlations to kinetic parameters related to external load during landing from drop jump. Perception of higher impacts could be used as a surrogate to monitor 'real' impacts and possibly also for managing impact-related injury risk.

Overall indexes of coordination in front crawl swimming.

The aim of this study was to propose a group of parameters able to quantify not only arm coordination but also inter limb coordination. These include the well know index of coordination with the relative duration of the stroke phases and two new parameters: the Index of synchronization (Ids) between arms and legs actions; and the Index of inter limb coordination (IdIC) calculated as the relative foot position during successive arm stroke phases. These parameters were compared between experts and amateur swimmers in a maximal front crawl sprint. The influence of arm stroke in leg kick parameters was also assessed, comparing the full stroke condition with a condition without arms actions. Sixty-five per cent of expert swimmers used synchronized limb actions while 95% of amateur swimmers used non-synchronized limb motions. These synchronized expert swimmers also converged towards a specific coordination pattern between foot position and arm stroke phases. In the condition without arms, both groups changed kick rate and amplitude. The present study reveals the interdependency of arms and legs actions and the importance of coordination and synchronization between limbs. Therefore, the proposed group of overall indexes of coordination provides a more complete marker for the analysis of swimming technique.

A High-Intensity Exercise Intervention Improves Older Women Lumbar Spine and Distal Tibia Bone Microstructure and Function: A 20-Week Randomized Controlled Trial.

Introduction: The effects of ageing on bone can be mitigated with different types of physical training, such as power training. However, stimuli that combine increasing external and internal loads concomitantly may improve bone quality. The goal of this study was to assess the efficacy of a combined power and plyometric training on lumbar spine and distal tibia microstructure and function. Methods: 38 sedentary elderly women between 60 and 70 years were randomly allocated in experimental (N = 21) and control group (N = 17). The effects of the 20-week protocol on lumbar spine microstructure and tibia microstructure and function were assessed by trabecular bone score (TBS), high resolution peripheral quantitative computed tomography (HR-pQCT) and microfinite element analysis. Results: when compared to the effects found in the control group, the experimental group showed significant improvements in lumbar spine TBS (Hedges' g = 0.77); and in distal tibia trabecular thickness (g = 0.82) and trabecular bone mineral density (g=0.63). Conclusion: our findings underscore the effectiveness of the proposed intervention, suggesting it as a new strategy to slow down and even reverse the structural and functional losses in the skeletal system due to ageing.

Muscle stretching changes neuromuscular function involved in ankle stability.

It has been postulated that the mechanical and neurophysiological effects induced by stretching decrease maximal muscle strength and power. Additionally, the reduction in neural input and muscle stiffness can affect the joint stabilization process. However, there is no evidence available to support this hypothesis. Thus, the aim of this study is to analyze the influence of static stretching on dynamic joint stability. Twenty physically active female university students (22.8 ± 5.3 years; 58 ± 8.8 kg; 1.62 ± 0.07 m) performed a series of static-passive stretching exercises for the peroneus longus and brevis muscles (four repetitions of 30 s). Before and after the stretches, electromyography was performed on both muscles during simulated ankle sprain. Mathematical algorithms calculate the latency and the electromyography activity (RMS). After stretching, the latency increased from 66ms to 73 ms (p = 0.003) for the peroneus brevis muscle and from 70 ms to 79 ms (p = 0.001) for the peroneus longus muscle. The RMS, calculated 100 ms after the simulation, decreased in the peroneus brevis muscle, from 25.05 to 18.16 (p = 0.001), and in the peroneus longus muscle, from 22.84 to 15.61 (p = 0.001). Muscle stretching changed the motor responses of both muscles. The increase in latency and the decrease in RMS indicate that static stretching influences the neuromuscular function involved in the joint stabilization process.

Sleep quality monitoring in individual sports athletes: parameters and definitions by systematic review.

In the present review, we identify which instruments and parameters are used for sleep quality monitoring in individual sport athletes and which definitions were used for sleep quality parameters in this literature field. Systematic searches for articles reporting the qualitative markers related to sleep in team sport athletes were conducted in PubMed, Scopus and Web of Science online databases. The systematic review followed the Preferred Reporting Items for Systematic Reviews. The initial search returned 3316 articles. After the removal of duplicate articles, eligibility assessment, 75 studies were included in this systematic review. Our main findings were that the most widely used measurement instruments were Actigraphy (25%), Rating Likert Scales (16%) and Sleep Diary (13%). On sleep quality parameters (Sleep duration = 14%; Wake after sleep onset = 14%; Sleep Quality = 12%; Sleep Effciency = 11% and Sleep Latency = 9%), the main point is that there are different definitions for the same parameters in many cases reported in the literature. We conclude that the most widely used instruments for monitoring sleep quality were Actigraphy, Likert scales and Sleep diary. Moreover, the definitions of sleep parameters are inconsistent in the literature, hindering the understanding of the sleep-sport performance relationship.

The effect of aquatic and treadmill exercise in individuals with chronic stroke / Efeito do treinamento aeróbio em piscina e em esteira em hemiparéticos crônicos / El efecto del ejercicio en piscina y en cinta de correr en pacientes hemiparéticos crónicos

ABSTRACT We compared the effect of gait training on treadmill versus deep water on balance and gait in 12 ischemic stroke chronic survivors randomly sorted to the Pool or Treadmill Groups. Berg Scale (BBS) and timed up and go test (TUG) were applied before and after the interventions. Just one person applied all tests and she was blinded for the aims of the study. Surface EMG of the paretic and non-paretic (NP) side muscles were recorded during walking on a treadmill. Three 100-ms epochs were extracted from the EMG related to gait phases: weight acceptance; propulsion; and pre-strike. For each epoch, we calculated the RMS of the EMG signal. Participants did gait training for 9 weeks (3 times/week, 40 minutes/session). The Pool group did the deep-water walking with a swimming belt. The Treadmill group walked on the treadmill at the maximum speed they could stand. The Manova group compared the effect of training, group, side, muscles, and gait phase into the EMG. Anova was used to test the effect of training, group side, and gait phase into BBS, TUG and EMG variables. Pool and Treadmill had increased balance and agility. The highest EMG RMS occurred at the paretic side, for the Treadmill and after training. The mm. tibialis anterior, gastrocnemius lateralis, vastus lateralis, and biceps femoris presented the highest RMS for the NP side; while for mm. rectus femoris and semitendinosus, the paretic side presented the highest RMS. Thus, the both types of exercise lead to similar functional adaptations with different muscular activations during walking.

RESUMO Comparamos o efeito do treinamento de marcha em esteira versus piscina no equilíbrio e na marcha em 12 sobreviventes crônicos de AVC isquêmico separados aleatoriamente nos grupos piscina ou esteira. A escala de Berg (EEB) e timed up and go test (TUG) foram aplicados antes e após as intervenções. A EMG de superfície dos músculos do lado parético e não parético foi registrada na caminhada em esteira. Três janelas de 100 ms foram extraídas da EMG relacionada às fases da marcha: aceitação de peso; propulsão; e pré-contato do pé. Para cada fase, calculou-se o RMS do sinal EMG. Os participantes treinaram 9 semanas (3 vezes/semana, 40 minutos/sessão). O grupo piscina fez marcha na água com cinto de natação. O grupo esteira fez treinamento de marcha na na velocidade máxima confortável. A Manova comparou o efeito do treinamento, grupo, lado, músculos e fase da marcha na EMG. A Anova testou o efeito do treinamento, lado do grupo e fase da marcha nas variáveis BBS, TUG e EMG. Os grupos piscina e esteira aumentaram o equilíbrio e a agilidade. O maior EMG RMS ocorreu no lado parético, no grupo esteira e após o treinamento. Os músculos: tibial anterior, gastrocnêmio lateral, vasto lateral e bíceps femoral apresentaram o maior RMS para o lado não parético; enquanto para os músculos reto femoral e semitendíneo, o lado parético apresentou o maior RMS. Assim, os dois tipos de exercício levaram a adaptações funcionais semelhantes com diferentes ativações musculares durante a caminhada.

RESUMEN Se comparó el efecto del entrenamiento de la marcha en cinta de correr y en piscina en el equilibrio y la marcha de 12 sobrevivientes crónicos de accidente cerebrovascular isquémico, quienes fueron clasificados aleatoriamente en los grupos piscina o cinta de correr. Se aplicaron la Escala de Equilibrio de Berg (BBS) y la Timed up and go test (TUG) antes y después de las intervenciones. Solo una persona aplicó todas las pruebas con evaluación ciega para los objetivos del estudio. Se registró la EMG de superficie de los músculos laterales paréticos y no paréticos durante la caminata en la cinta. Se extrajeron tres momentos de 100 ms de la EMG relacionadas con las etapas de la marcha: aceptación de peso; propulsión; y precontacto del pie. Para cada momento, se calculó el RMS de la señal EMG. Los participantes realizaron entrenamientos de marcha durante 9 semanas (3 veces/semana, 40 minutos/sesión). El grupo piscina caminó con un cinturón de natación. El grupo cinta de correr caminó en la cinta a la velocidad máxima confortable. Utilizando la Manova se comparó el efecto del entrenamiento, el grupo, los músculos laterales y la fase de la marcha en la EMG. Con la ANOVA se probó el efecto del entrenamiento, el lado grupal y la fase de marcha en las variables BBS, TUG y EMG. El equilibrio y la agilidad aumentaron en ambos grupos. El EMG RMS más alto ocurrió en el lado parético del grupo cinta de correr y después del entrenamiento. Los músculos tibial anterior, gastrocnemio lateral, vasto lateral y bíceps femoral presentaron el RMS más alto en el lado no parético; mientras que en los músculos recto femoral y semitendinoso, el lado parético presentó el RMS más alto. Por lo tanto, los dos tipos de ejercicio conducen a adaptaciones funcionales similares con diferentes activaciones musculares durante la marcha.

Creatine supplementation can improve impact control in high-intensity interval training.

OBJECTIVES: This study aimed to investigate the effects of creatine (Cr) supplementation on biomechanical parameters related to shock attenuation during a session of high-intensity interval training (HIIT). METHODS: A single-blinded, placebo-controlled, crossover design was adopted to test eight male elite soccer players during HIIT sessions under two conditions: after placebo supplementation and after Cr supplementation. HIIT test sessions consisted of an intermittent test (five bouts of running) with a constant load applied until exhaustion was reached. The vertical component of ground reaction force and electromyography data were recorded by Gaitway and Lynx-EMG Systems, respectively. Heart rate, rated perceived exertion (Borg's Scale) and lactate concentration information were also obtained. RESULTS: Cr supplementation did not affect heart rate, rated perceived exertion, and lactate concentration. Decreased values of magnitude of the first peak of the vertical component of ground reaction force (17.2-24.2%) and impulse of the first 50 ms (Imp50; 34.3%) were observed for Cr, but higher values of time to reach the first peak were detected for Cr compared with placebo. Significant modifications in muscle activation were also observed, mainly in the pre-activation phase, and changes were observed in intermediary bouts. CONCLUSIONS: Cr supplementation has the potential to influence biomechanical parameters related to impact control during a single session of HIIT based on running. In particular, the findings of the current study indicate possible improvements in shock attenuation and a safer practice of HIIT under Cr supplementation.

Immediate effects of a distal gait modification during stair descent in individuals with patellofemoral pain.

Background: Knee pain during stair managing is a common complaint among individuals with PFP and can negatively affect their activities of daily living. Gait modification programs can be used to decrease patellofemoral pain. Immediate effects of a stair descent distal gait modification session that intended to emphasize forefoot landing during stair descent are described in this study. Objectives: To analyze the immediate effects of a distal gait modification session on lower extremity movements and intensity of pain in women with patellofemoral pain during stair descent. Method: Nonrandomized controlled trial. Sixteen women with patellofemoral pain were allocated into two groups: (1) Gait Modification Group (n = 8); and 2) Control Group (n = 8). The intensity of pain (visual analog scale) and kinematics of knee, ankle, and forefoot (multi-segmental foot model) during stair descent were assessed before and after the intervention. Results: After the gait modification session, there was an increase of forefoot eversion and ankle plantarflexion as well as a decrease of knee flexion. An immediate decrease in patellofemoral pain intensity during stair descent was also observed. Conclusion: The distal gait modification session changed the lower extremity kinetic chain strategy of movement, increasing foot and ankle movement contribution and decreasing knee contribution to the task. An immediate decrease in patellofemoral pain intensity during stair descent was also observed. To emphasize forefoot landing may be a useful intervention to immediately relieve pain in patients with patellofemoral pain during stair descent. Clinical studies are needed to verify the gait modification session effects in medium and long terms.