Myofascial release strategies and technique recommendations for athletic performance: A systematic review.

OBJECTIVE: To identify the effects of instrument-assisted soft tissue mobilization (IASTM) and foam roller self-myofascial release (FRSMR) strategies and verify their results in athletic performance. METHOD: Systematic review conducted in four databases from 2017. The inclusion criteria were randomized controlled trials assessing the effects of two forms of soft tissue mobilization on athletes' performance. The risk of bias was analyzed using the Cochrane Handbook scale. RESULTS: Ten studies were included for qualitative analysis. IASTM increased range of motion, knee joint kinetic force, peak torque, and angular velocity in dorsiflexion and plantar flexion. The technique increases isometric strength and isokinetic power in vertical jumping. FRSMR was relevant in counter movement jumping between the pre- and post-intervention conditions, mainly by increasing strength in the initial jumping phase. CONCLUSIONS: IASTM should be used in sports preparation to improve muscle response and explosive force production. FRSMR increases flexibility as it tends to restore tissue elasticity, but it does not improve aerobic activity. The suggested time for strategy intervention is at least 90 s per muscle group.

Activation, strength, and resistance: Which variables predict the kinematics of women with and without patellofemoral pain?

INTRODUCTION: Investigating the possible relationship between neuromuscular changes and movement alterations could help to describe the mechanisms underlying patellofemoral pain (PFP). OBJECTIVE: To investigate whether activation and muscle strength of the trunk and lower limb and muscle resistance of the trunk predict the knee frontal and trunk sagittal kinematics in women with and without PFP. METHOD: Sixty women (PFP, n = 30; asymptomatic, n = 30) underwent the single-leg squat test to collect electromyographic and kinematic data. Activation of transversus abdominis/internal oblique, gluteus medius (GMed), and vastus medialis oblique (VMO); knee frontal and trunk sagittal angles were analyzed. Participants also underwent maximal isometric tests to determine lateral trunk, hip abductor, and knee extensor torques and performed a lateral trunk resistance test. Multiple regression was used to determine predictive models. RESULTS: In the PFP group, knee frontal angle (R2 = 0.39, p = 0.001) was predicted by GMed activation (ß = 0.23, p = 0.000) and hip abductor torque (ß = 0.08, p = 0.022). No variable was able to predict trunk sagittal kinematics in this group. In the asymptomatics, knee frontal angle (R2 = 0.16, p = 0.029) was predicted by hip abductor torque (ß = 0.07, p = 0.029), while trunk sagittal angle (R2 = 0.24, p = 0.024) was predicted by VMO activation (ß = 0.12, p = 0.016). CONCLUSION: Kinematics is predicted by the muscles acting in the respective planes, such that hip abductors capacities are related to the knee frontal alignment in both groups, and that of the VMO is related to the trunk sagittal alignment only in asymptomatic women.

Biomechanical effects of typical lower limb movements of Chen-style Tai Chi on knee joint.

The load and stress distribution on cartilage and meniscus of the knee joint in typical lower limb movements of Chen-style Tai Chi (TC) and deep squat (DS) were analyzed using finite element (FE) analysis. The loadings for this analysis consisted of muscle forces and ground reaction force (GRF), which were calculated through the inverse dynamic approach based on kinematics and force plate measurements obtained from motion capture experiments. Thirteen experienced practitioners performed four typical TC movements, namely, single whip (SW), brush knee and twist step (BKTS), stretch down (SD), and part the wild horse's mane (PWHM), which exhibit lower posture and greater lower limb force compared to other TC styles. The results indicated that TC required greater lower limb muscle strength than DS, resulting in greater knee joint forces. The stress on the medial cartilage in SW and BKTS fell within a range conductive to maintaining the balance between anabolism and catabolism of cartilage matrix. This was due to the fact that SW and BKTS reduce the medial to total tibiofemoral contact force ratios through knee abduction, which may effectively alleviate mild medial knee osteoarthritis (KOA). However, the greater medial contact force ratios observed in SD and PWHM resulted in great contact stresses that may aggravate the pain of patients with KOA. To mitigate these effects, practitioners should consider elevating their postures appropriately to reduce knee flexion angles, especially during the single-leg support phase. This adjustment can decrease the required muscle strength, load and stress on the knee joint.

Comparison of utilizing modified hold-relax, muscle energy technique, and instrument-assisted soft tissue mobilization on hamstring muscle length in healthy athletes: Randomized controlled trial.

INTRODUCTION: The hamstring muscle shortness is the primary risk factor for sports-related injuries. Numerous treatments are available for lengthening of hamstring muscle. The main purpose of this study was to compare the immediate effect of modified hold-relax, muscle energy technique (MET), and instrument assisted soft tissue mobilization-Graston techniques (IASTM-GT) on length of hamstring muscle in young healthy athletes. METHODS: 60 athletes comprising of 29 females and 31 males were recruited in the present study. Participants were allocated to 3 groups of IASTM-GT (N = 20, 13 male, 7 female), Modified Hold-relax (N = 20, 8 male, 12 female), and MET (N = 20, 7 male, 13 female). Active knee extension and passive straight leg raising (SLR), and toe touch test were performed before and immediately after the intervention by a blinded assessor. For the comparison of dependent variables across time, 3*2 repeated measure ANOVA was utilized. RESULTS: Interaction of group by time was significant for passive SLR (P < 0.001). Interaction of group by time was not significant for active knee extension (P = 0.17). The results showed that dependent variables increased significantly in all groups. The effect size (Cohen's d) in the groups of IASTM-GT, modified Hold-relax, and MET was 1.7, 3.17, and 3.12, respectively. CONCLUSION: Although the measures were improved in all groups, it seems that IASTM-GT can be used as a safe and efficient treatment, which can be a suitable candidate alongside modified hold-relax and MET for increasing the hamstrings muscle length in healthy athletes.

Comparison of muscle activity of hamstrings as knee flexors and hip extensors and effect of tibial and hip rotation on the contribution of hamstrings.

BACKGROUND: Limited studies have compared the muscle activity of the medial and lateral hamstrings as knee flexors with tibial internal and external rotation and hip extensors with hip internal and external rotation. In particular, hamstring activity during hip extension with hip rotation has rarely been investigated. OBJECTIVE: This study aimed to compare the muscle activity of the medial and lateral hamstrings as knee flexors and hip extensors and to compare the activity of these muscles according to tibial rotation during isometric knee flexion and hip rotation during isometric hip extension. METHODS: A total of 23 healthy adults participated in the study. The electromyographic (EMG) activity of the hamstrings was measured during maximal isometric knee flexion and maximal isometric hip extension. In addition, tibial rotation was applied actively during maximal isometric knee flexion, whereas hip rotation was applied actively during maximal isometric hip extension. RESULTS: EMG activity during maximal isometric knee flexion with tibial internal and external rotation was significantly higher than that during maximal isometric hip extension with hip internal and external rotation, respectively. For EMG activity according to tibial and hip rotation, there was no significant difference between tibial internal and external rotation during maximal isometric knee flexion, whereas there was a significant difference between hip internal and external rotation during maximal isometric hip extension. CONCLUSION: Hamstring activity was higher for knee flexors than for hip extensors. However, hip rotation during maximal isometric hip extension is an effective intervention for selective muscle activation of the medial and lateral hamstrings.

Newly compiled Tai Chi (Bafa Wubu) promotes lower extremity exercise: a preliminary cross sectional study.

Background: Tai Chi (Bafa Wubu) is a new type of simplified Tai Chi widely practiced by Tai Chi enthusiasts that has developed and perfected simplified Tai Chi movement and enriched Tai Chi practice methods. When practicing, Tai Chi athletes and enthusiasts can choose the Bafa Wubu movements to practice according to their physical conditions. The purpose of this article is to discuss the mechanism by which Bafa Wubu promotes lower extremity exercise from the perspective of exercise biomechanics. Objectives: This article aims to explore the scientific training methods and technical characteristics of Bafa Wubu, and its contribution to comprehensive exercise of the lower extremities, by analyzing the biomechanical characteristics of the lower extremities of participants who practice Bafa Wubu at different levels and by comparing their ground reaction force, lower limb joints, and muscles during Bafa Wubu. Methods: A total of 16 male participants were recruited and divided into an amateur group (N = 8) and a professional group (N = 8). The data were collected by a BTS 3D infrared-based motion capture system, and Kistler 3D force plate. The lower extremity joint forces and muscle strength were calculated by anybody simulation software with inverse dynamics. Results: During elbowing and leaning sideways with steps sideways (ELS), the ground reaction force of the professional group was significantly higher than that of the amateur group in the sagittal, vertical, and frontal axes (P < 0.01). While stepping forward, backward, and sideways, the professional group's joints loading at the hip, knee, and ankle was always higher in the vertical direction (P < 0.01). Furthermore, during warding off with steps forward (WOF), laying with steps forward (LF), and rolling back with steps backward (RBB), hip joint loading increased in the med-lat direction. During actions with steps backward and sideways, the professional group's ankle flexion/extension torque and hip abduction/rotation torque were significantly larger than those of the amateur group (P < 0.01). Different actions in Bafa Wubu activate muscles to different degrees, whereas the iliacus is mainly responsible for stabilizing postures when practitioners perform standing knee lifting motions. Conclusions: Professional groups who have been practicing Tai Chi (Bafa Wubu) for a long time have higher ground reaction force, and the force on the three joints of the lower extremities is different for various movements, which has positive significance for exercising the joints of the lower extremities. In addition, various motions activate muscles of different types at different levels. For amateurs to practice different movements to stimulate the muscles, targeted areas of practice promote the lower extremity muscles' synergistic force. In summary, the muscles and joints of the lower extremity can obtain comprehensive and balanced exercise through Bafa Wubu.

Voluntary torque production is unaffected by changes in local thermal sensation during normothermia and hyperthermia.

NEW FINDINGS: What is the central question of this study? Hyperthermia reduces the human capacity to produce muscular force, which is associated with decreased neural drive: does mitigating a reduction in neural drive by altering localised thermal sensation help to preserve voluntary force output? What is the main finding and its importance? Altering thermal sensation by cooling and heating the head independent of core temperature did not change neural drive or benefit voluntary force production. Head cooling did slow the rate of rise in core temperature during heating, which may have practical applications in passive settings. ABSTRACT: This study investigated altered local head and neck thermal sensation on maximal and rapid torque production during voluntary contractions. Nine participants completed four visits in two environmental conditions: at rectal temperatures ∼39.5°C in hot (HOT; ∼50°C, ∼39% relative humidity) and ∼37°C in thermoneutral (NEU; ∼22°C, ∼46% relative humidity) conditions. Local thermal sensation was manipulated by heating in thermoneutral conditions and cooling in hot conditions. Evoked twitches and octets were delivered at rest. Maximum voluntary torque (MVT), normalised surface electromyography (EMG) and voluntary activation (VA) were assessed during brief maximal isometric voluntary contractions of the knee extensors. Rate of torque development (RTD) and EMG were measured during rapid voluntary contractions. MVT (P = 0.463) and RTD (P = 0.061) were similar between environmental conditions despite reduced VA (-6%; P = 0.047) and EMG at MVT (-31%; P = 0.019). EMG in the rapid voluntary contractions was also lower in HOT versus NEU during the initial 100 ms (-24%; P = 0.035) and 150 ms (-26%; P = 0.035). Evoked twitch (+70%; P < 0.001) and octet (+27%; P < 0.001) RTD during the initial 50 ms were greater in the HOT compared to NEU conditions, in addition to a faster relaxation rate of the muscle (-33%; P < 0.001). In conclusion, hyperthermia reduced neural drive without affecting voluntary torque, likely due to the compensatory effects of improved intrinsic contractile function and faster contraction and relaxation rates of the knee extensors. Changes in local thermal perception of the head and neck whilst hyperthermic or normothermic did not affect voluntary torque.

Heat acclimation reduces the effects of whole-body hyperthermia on knee-extensor relaxation rate, but does not affect voluntary torque production.

PURPOSE: This study investigated the effects of acute hyperthermia and heat acclimation (HA) on maximal and rapid voluntary torque production, and their neuromuscular determinants. METHODS: Ten participants completed 10 days of isothermic HA (50 °C, 50% rh) and had their knee-extensor neuromuscular function assessed in normothermic and hyperthermic conditions, pre-, after 5 and after 10 days of HA. Electrically evoked twitch and octet (300 Hz) contractions were delivered at rest. Maximum voluntary torque (MVT), surface electromyography (EMG) normalised to maximal M-wave, and voluntary activation (VA) were assessed during brief maximal isometric voluntary contractions. Rate of torque development (RTD) and normalised EMG were measured during rapid voluntary contractions. RESULTS: Acute hyperthermia reduced neural drive (EMG at MVT and during rapid voluntary contractions; P < 0.05), increased evoked torques (P < 0.05), and shortened contraction and relaxation rates (P < 0.05). HA lowered resting rectal temperature and heart rate after 10 days (P < 0.05), and increased sweating rate after 5 and 10 days (P < 0.05), no differences were observed between 5 and 10 days. The hyperthermia-induced reduction in twitch half-relaxation was attenuated after 5 and 10 days of HA, but there were no other effects on neuromuscular function either in normothermic or hyperthermic conditions. CONCLUSION: HA-induced favourable adaptations to the heat after 5 and 10 days of exposure, but there was no measurable benefit on voluntary neuromuscular function in normothermic or hyperthermic conditions. HA did reduce the hyperthermic-induced reduction in twitch half-relaxation time, which may benefit twitch force summation and thus help preserve voluntary torque in hot environmental conditions.

Atletas de Taekwondo apresentam desequilíbrio muscular entre os músculos flexores e extensores do joelho: achados preliminares / Taekwondo athletes have muscle imbalance between knee flexors and extensions: preliminary findings / Los atletas de Taekwondo presentan un desequilibrio muscular entre los flexores y los extensores de la rodilla: hallazgos preliminares

Durante a prática de taekwondo com movimentos repetitivos, sistematizados e com certa sobrecarga de treino, o indivíduo pode gerar possíveis adaptações orgânicas que resultam em problemas posturais com grandes chances de desencadear desequilíbrio muscular. Objetivo: Verificar a presença de desequilíbrio entre os grupos musculares agonistas e antagonistas da articulação do joelho e entre membros dominantes e não dominantes de praticantes de taekwondo por meio da dinamometria isocinética. Método: Estudo transversal, observacional e descritivo realizado com nove praticantes de taekwondo do sexo masculino. Utilizou-se um dinamômetro isocinético para investigar o pico de torque, pico de torque por peso corporal, trabalho total, potência média, relação agonista/antagonista e índice de fadiga. Os dados dos membros dominante e não dominante foram comparados por meio do teste t-student para amostras pareadas. Foram calculados o intervalo de confiança de 95% da diferença média, o tamanho de efeito e o poder das análises. Resultados: Os músculos extensores dos membros dominante e não dominante apresentaram diferença média significante de 15,49 Nm (IC95% 7,27; 23,70; p=0,002) para pico de torque e de 22,64% (IC95% 11,83; 33,46; p=0,001) para pico de torque por peso corporal a 60°/s, representando tamanho de efeito médio. Conclusão: Os atletas de taekwondo apresentaram maior pico de torque e maior pico de torque por peso corporal dos músculos extensores do joelho a 60º/s no lado dominante. A relação agonista/ antagonista foi inferior a 60% e mais da metade dos atletas apresentaram uma diferença maior que 10% no pico de torque flexor no lado não dominante.

During taekwondo practice with the repetitive motions, systematized and with certain training overload, the person can generate possible organic adaptations that result in postural problems with a great chances of triggering muscle imbalance. Objective: To verify the presence of imbalance between agonist and antagonist muscle groups of knee joint and between dominant and non-dominant limbs through isokinetic dynamometry. Methods: Cross-sectional, observational and descriptive study realized with nine male taekwondo practitioners. An isokinetic dynamometer was used to investigate the peak torque, peak torque by body weight, total work, average power, agonist/antagonist ratio and fatigue index. Data from the dominant and non-dominant limbs were compared by t-student test for pared samples. The 95% confidence interval of the mean difference, the effect size and the power of analyses power were calculated. Results: The extensor muscles of the dominant and non-dominant limbs showed mean difference of 15,49 Nm (IC95% 7,27; 23,70; p=0,002) for peak torque and of 22,64% (IC95% 11,83; 33,46; p=0,001) for peak torque by body weight at 60°/s, representing average effect size. Conclusion: The taekwondo athletes had higher peak torque and higher peak torque by body weight of the knee extensors muscles in the dominant side. The agonist/ antagonist ratio was less than 60% and more than half of the athletes showed a difference greater than 10% in the peak flexor torque on the non-dominant side.

Durante la práctica de taekwondo con los movimientos repetitivos, sistematizados y con cierta sobrecarga de entrenamiento, la persona puede generar posibles adaptaciones orgánicas que deriven en problemas posturales con grandes posibilidades de desencadenar desequilibrios musculares. Objetivo: Verificar la presencia de desequilibrio entre grupos musculares agonistas y antagonistas de la articulación de la rodilla y entre miembros dominantes y no dominantes mediante dinamometría isocinética. Métodos: Estudio transversal, observacional y descriptivo realizado con nueve practicantes masculinos de taekwondo. Se utilizó un dinamómetro isocinético para investigar el par máximo, el par máximo por peso corporal, el trabajo total, la potencia media, la relación agonista/antagonista y el índice de fatiga. Los datos de las extremidades dominantes y no dominantes se compararon mediante la prueba t- student para muestras de pared. Se calcularon el intervalo de confianza del 95% de la diferencia media, el tamaño del efecto y la potencia de los análisis. Resultados: Los músculos extensores de los miembros dominantes y no dominantes mostraron una diferencia media de 15,49 Nm (IC95% 7,27; 23,70; p=0,002) para el par máximo y de 22,64% (IC95% 11,83; 33,46; p=0,001) para el par máximo por peso corporal a 60°/s, lo que representa el tamaño medio del efecto. Conclusiones: Los atletas de taekwondo presentaron un mayor par máximo y un mayor par máximo por peso corporal de los músculos extensores de la rodilla en el lado dominante. La relación agonista/antagonista fue inferior al 60% y más de la mitad de los atletas mostraron una diferencia superior al 10% en el pico de par flexor en el lado no dominante.

A Wirelessly Powered 4-Channel Neurostimulator for Reconstructing Walking Trajectory.

A wirelessly powered four-channel neurostimulator was developed for applying selective Functional Electrical Stimulation (FES) to four peripheral nerves to control the ankle and knee joints of a rat. The power of the neurostimulator was wirelessly supplied from a transmitter device, and the four nerves were connected to the receiver device, which controlled the ankle and knee joints in the rat. The receiver device had functions to detect the frequency of the transmitter signal from the transmitter coil. The stimulation site of the nerves was selected according to the frequency of the transmitter signal. The rat toe position was controlled by changing the angles of the ankle and knee joints. The joint angles were controlled by the stimulation current applied to each nerve independently. The stimulation currents were adjusted by the Proportional Integral Differential (PID) and feed-forward control method through a visual feedback control system, and the walking trajectory of a rat's hind leg was reconstructed. This study contributes to controlling the multiple joints of a leg and reconstructing functional motions such as walking using the robotic control technology.

Motion Sensors for Knee Angle Recognition in Muscle Rehabilitation Solutions.

The progressive loss of functional capacity due to aging is a serious problem that can compromise human locomotion capacity, requiring the help of an assistant and reducing independence. The NanoStim project aims to develop a system capable of performing treatment with electrostimulation at the patient's home, reducing the number of consultations. The knee angle is one of the essential attributes in this context, helping understand the patient's movement during the treatment session. This article presents a wearable system that recognizes the knee angle through IMU sensors. The hardware chosen for the wearables are low cost, including an ESP32 microcontroller and an MPU-6050 sensor. However, this hardware impairs signal accuracy in the multitasking environment expected in rehabilitation treatment. Three optimization filters with algorithmic complexity O(1) were tested to improve the signal's noise. The complementary filter obtained the best result, presenting an average error of 0.6 degrees and an improvement of 77% in MSE. Furthermore, an interface in the mobile app was developed to respond immediately to the recognized movement. The systems were tested with volunteers in a real environment and could successfully measure the movement performed. In the future, it is planned to use the recognized angle with the electromyography sensor.

Immediate effect of MWM adductor stretch, myofascial release, and conventional stretching in asymptomatic individuals with hip adductor tightness: A randomized controlled trial.

BACKGROUND: Hip adductors are the group of muscles that stabilize the pelvis during weight transfer in lower limbs in a gait cycle. As the full range of motion is seldomly used, this group of muscles commonly go into tightness which in turn may be a predisposing factor in development of back pain and knee pain. METHODS: 54 healthy individuals were selected after screening for bilateral hip adductor tightness by measuring hip abduction range of motion using goniometer. They were randomized to either mobilization with movement (MWM) adductor stretch, myofascial release, or conventional stretching group. All subjects were assessed pre and post intervention. Outcome measure used were hip abduction range of motion and bent knee fall out test. RESULTS: Statistically significant difference was noted between the experimental and the control group in terms of hip abduction range of motion and bent knee fall out test. CONCLUSION: Intervention showed significant results in all three groups; however, MWM adductor stretch when used in conjunction with conventional stretching has proved to be more effective than myofascial release with foam roller and conventional stretching in increasing the abduction range of motion and bent knee fall out test.

Muscle coordination retraining inspired by musculoskeletal simulations reduces knee contact force.

Humans typically coordinate their muscles to meet movement objectives like minimizing energy expenditure. In the presence of pathology, new objectives gain importance, like reducing loading in an osteoarthritic joint, but people often do not change their muscle coordination patterns to meet these new objectives. Here we use musculoskeletal simulations to identify simple changes in coordination that can be taught using electromyographic biofeedback, achieving the therapeutic goal of reducing joint loading. Our simulations predicted that changing the relative activation of two redundant ankle plantarflexor muscles-the gastrocnemius and soleus-could reduce knee contact force during walking, but it was unclear whether humans could re-coordinate redundant muscles during a complex task like walking. Our experiments showed that after a single session of walking with biofeedback of summary measures of plantarflexor muscle activation, healthy individuals reduced the ratio of gastrocnemius-to-soleus muscle activation by 25 ± 15% (p = 0.004, paired t test, n = 10). Participants who walked with this "gastrocnemius avoidance" gait pattern reduced late-stance knee contact force by 12 ± 12% (p = 0.029, paired t test, n = 8). Simulation-informed coordination retraining could be a promising treatment for knee osteoarthritis and a powerful tool for optimizing coordination for a variety of rehabilitation and performance applications.

Auditory sEMG biofeedback for reducing muscle co-contraction during pedaling.

Muscle co-contraction between the agonist and antagonist muscles often causes low energy efficiency or movement disturbances. Surface electromyography biofeedback (sEMG-BF) has been used to train muscle activation or relaxation but it is unknown whether sEMG-BF reduces muscle co-contraction. We hypothesized that auditory sEMG-BF improves muscle co-contraction. Our purpose was to investigate whether auditory sEMG-BF is effective in improving muscle co-contraction. Thirteen participants pedaled on a road bike using four different auditory sEMG-BF conditions. We measured the surface electromyography at the lower limb muscles. The vastus lateralis (VL) and the semitendinosus (ST) activities were individually transformed into different beep sounds. Four feedback conditions were no-feedback, VL feedback, ST feedback, and both VL and ST feedback. We compared the co-contraction index (COI) of the knee extensor-flexor muscles and the hip flexor-extensor muscles among the conditions. There were no significant differences in COIs among the conditions (p = 0.83 for the COI of the knee extensor-flexor; p = 0.32 for the COI of the hip flexor-extensor). To improve the muscle co-contraction by sEMG-BF, it may be necessary to convert muscle activation into a muscle co-contraction. We concluded that individual sEMG-BF does not immediately improve muscle co-contraction during pedaling.

Varying alignment affects lower extremity joint and limb loading during yoga's triangle (Trikonasana) pose.

BACKGROUND: Limited biomechanical data exist describing how yoga asanas (postures) load the limbs and joints, and little evidence-based recommendations for yoga injury prevention are available. This study aimed to establish joint loading metrics for an injury-prone, yet common yoga pose, the Triangle asana (Trikonasana) by identifying how stance width adjustments alter lower extremity loading. METHODS: Eighteen yoga practitioners underwent 3D motion analysis while performing Trikonasana with self-selected (SS) stance width and -30, -20, -10, +10, +20, and +30% of SS stance width. Ground reaction forces (GRFs), joint forces, and joint moments were calculated for the leading and trailing limb ankle, knee, and hip. One-way repeated-measures analysis of variance determined differences in loading due to stance width. RESULTS: GRFs, net joint forces, and net joint moments were significantly affected by stance width where increasing stance width increased leading limb loading but decreased trailing limb loading. CONCLUSIONS: Altering stance width of Trikonasana influences lower extremity limb loading, and these loading responses were limb-dependent. Yoga practitioners and instructors can use this information to objectively support increasing or decreasing stance width to reduce or increase limb loading according to their goals or to make accommodations to groups such as beginners or at-risk populations for safer, more accessible yoga practices. Cuing a wider or narrower stance width will not have the same effect on both limbs.

Effects of 6-weeks of detraining on functional capacity and rapid torque production in older women.

Mat Pilates has become an attractive alternative exercise among older women, however, despite knowing the importance of regular exercise, interrupting training is a common issue in this population. The aim of the current study was to evaluate the effects of 6-weeks of detraining after a period of 12-weeks of training with Mat Pilates on the functional capacity and neuromuscular performance of the knee extensor muscles in older women. Ten older women (62.6 ± 2.6 years; 1.57 ± 0.05 m height; 69.3 ± 9.2 kg; 27.8 kg/m2 body mass index) volunteered to participate in this study. The study was divided into three periods: a 4-week control period, followed by 12 weeks of Mat Pilates intervention, and a 6-week detraining period. During the intervention, the results showed significant improvements in functional capacity tests (time up and go, time up stairs, time down stairs, and chair sit-and-reach), rate of torque development, and impulse (p < 0.05). After the detraining period, a decrease was observed in the chair sit-and-reach test (p < 0.05) and contractile impulse at intervals 0-30 and 0-50 ms (p < 0.05). We conclude that a 6-week detraining period after a Mat Pilates training protocol was sufficient to cause declines in the chair sit-and-reach test and in the contractile impulse of the knee extensors in the early phase of the torque-time curve (0-30 and 0-50 ms), but not in the other functional capacity tests and neuromuscular parameters evaluated.

Differences in Pivot Leg Kinematics and Electromyography Activation in Various Round House Kicking Heights.

The round house kick (RHK) is a common technique in taekwondo (TKD). The kicking action originates from the dynamic stability of the pivot leg. However, some knee injuries are caused by more difficult kicking strategies, such as kicks to the opponent's head. This study analyses the effects on TKD players in the lower extremity kinematic and neuromuscular reactions from different kicking heights. This study recruited 12 TKD players (age=20.3 ± 1.3 years, height = 1.72 ± 0.09 m, mass = 62.17 ± 9.45 kg) with no previous lower extremity ligament injuries. All athletes randomly performed 3 RHK at different heights (head, chest, and abdomen), repeating each kick 5 times. During the RHK action, the kinematics and muscle activations of the pivot leg were collected using six high-speed cameras and electromyography devices. The results found that during the RHK return period a high kicking position demonstrated larger knee valgus with the straight knee, and more hamstring activation on the pivot leg. The RHK pivot foot for TKD players encountered more risk of injury from high target kicking. The hamstring muscle played an important stabilizing role. It is recommended that sports medicine clinicians or sports coaches use this information to provide further protective injury prevention strategies.

Lower extremity joint loading during Bounce rope skip in comparison to run and walk.

BACKGROUND: Bounce rope-skip holds immense scope as an aerobic exercise in space and time constrained urban setting with additional constraints placed by pandemic situations such as Covid 19, wherein adherence to commonly performed weight-bearing, aerobic activities like walking and running is a challenge. Limited knowledge informing biomechanical demands and misconceptions about knee joint loading, confines safe application of bounce rope-skip in health promotion. Thus, present study aimed to explore kinematics and lower-extremity joint loading during rope-skipping compared to walking and running. METHODS: Following ethical approval, 3D motion analysis of bounce rope-skip, walk and run was captured from 22 healthy female participants aged 18-25yr using 12-camera Vicon system and 2AMTI force plates. Three trials for bounce rope-skip were recorded with five skip-jumps on force-plates at a cadence of 105 skips/min. Mid-skip, mid-gait and mid-run data were averaged to compute kinetic and kinematic variables for hip, knee and ankle during loading/initial contact, take-off/push-off and flight/mid-swing phases of rope-skip, walk and run. RESULT: Average time of one rope-skip cycle was 1.2sec; mean foot contact time was 0.55sec and flight time was 0.65sec. In one bounce rope-skip cycle, hip motion ranged between 13.4o-35.3oflexion; knee between 13.6 o-67.9° flexion and ankle between 34.5odorsiflexion to-13.40plantarflexion. Vertical ground reaction force (vGRF) during rope-skip (landing-phase) was lower compared to run; however, it was higher than walk (p < 0.001). In coronal plane, peak hip and knee adductor moment during rope-skip were lower compared to run and higher than walk (p < 0.001). CONCLUSION: Bounce rope-skip generated low lower extremity joint loading compared to run; supporting its prescription as a hip and knee joint-protective aerobic weight-bearing exercise for health promotion in young adults.

Type 2 Diabetes Mellitus Patients Manifest Greater Muscle Fatigability Than Healthy Individuals During Dynamic Fatigue Protocol.

OBJECTIVE: The present study aimed to investigate the electromyographic (EMG) indices of muscle fatigue along with biochemical marker of fatigue-that is, blood lactate-during a dynamic fatigue protocol in individuals with type 2 diabetes mellitus (T2DM) vs a healthy control group. Secondarily, it aimed to examine the association between EMG indices of muscle fatigue and blood lactate in these patients. METHODS: Thirty-four participants took part in the study: 19 individuals with T2DM (age, 53.5 ± 6.85 years) and 15 age-matched healthy controls (age, 50.2 ± 3.55 years). Participants performed a dynamic fatigue protocol consisting of 5 sets of 10 repetitions each at an intensity of the 10-repetition maximum. Surface EMG of the vastus medialis and vastus lateralis muscles was recorded during the dynamic fatigue protocol, and EMG indices such as median frequency (MF), slope of MF (MFslope), Dimitrov muscle fatigue spectral index, and root-mean-square were evaluated for each contraction across all the 5 sets. Blood lactate concentrations were also assessed 3 times during the fatigue protocol. RESULTS: Findings revealed that EMG muscle fatigue indices such as MF, MFslope, and Dimitrov muscle fatigue spectral index were significantly altered in individuals with T2DM vs healthy individuals across the sets and repetitions for both the vastus medialis (P < .001) and vastus lateralis muscles (P < .001). There was a significantly greater rise in blood lactate in individuals with T2DM than in healthy individuals (P < .001), which was not found to be associated with changes in EMG indices of muscle fatigue. CONCLUSION: Findings suggest the existence of significantly greater fatigue in the knee extensor muscles of individuals with T2DM than healthy individuals.

Exercise with TENS does not augment gains in balance and strength for dancers.

Electrical stimulation modulates sensory feedback and improves motor performance, at least for individuals with compromised sensorimotor function. The purpose of this study was to determine the effectiveness of a 4-wk intervention with transcutaneous electrical nerve stimulation (TENS) at improving strength and balance in dancers. Nineteen dancers completed a timed, single-leg balance test, the Y-balance test, and contractions with the hip flexor and knee extensor muscles to assess maximal strength and force steadiness. They completed 4-wks of moderate-intensity bodyweight exercises (3x/wk) and were pseudo-randomized to either a Treatment or Sham group in a single-blind design. The Treatment group received constant TENS over the hamstring muscles during the exercises, whereas the Sham group was exposed to a brief TENS current. The data were pooled due to few significant between-group differences from before to after the intervention. Most outcome measures significantly improved: hip extensor muscles were stronger (P ≤ 0.01), time stood on a single-leg with eyes closed increased (P = 0.02), and the distance reached during the Y-balance test increased (P ≤ 0.001). The improvement in scores on the Y-balance test exceeded the minimal clinically significant change. Twelve sessions of moderate-intensity bodyweight exercises improved muscle strength and balance in experienced dancers. The addition of TENS, however, did not augment the gains in function.