Function, strength, and muscle activation of the shoulder complex in Crossfit practitioners with and without pain: a cross-sectional observational study

Background The shoulder joint is the most commonly injured joint in CrossFit practitioners, because of the high intensity and loads associated with this sport. Despite the large number of clinical cases, there is a shortage of studies that investigate influence of biomechanical aspects of upper limbs' injuries on CrossFit practitioners. This study hypothesized that there would be a difference in function, strength, and muscle activation between Crossfit practitioners with and without shoulder pain. Methods We divided 79 Crossfit practitioners into two groups according to whether they reported pain (n = 29) or no pain (n = 50) in the shoulder during Crossfit training. Muscle function, strength, and activation were assessed using the Disability Arm, Shoulder and Hand function questionnaire, Upper Quarter Y Balance Test and Closed Kinetic Chain Upper Extremity Stability Test shoulder tests, isometric muscle strength assessment by manual dynamometry and muscle activation by surface electromyography and pain report. Results The function based on questionnaire was associated with pain (p = 0.004). We observed a statistically significant difference between the two groups only in the surface electromyography activity of the lower trapezius, and in the variables of shoulder pain and function (p = 0.038). Conclusion Crossfit practitioners with shoulder pain occurring during training showed good function and stability of the shoulder joint, but there was a reduction in the activation of stabilizing muscles, especially the lower trapezius. Trial registration Registro Brasileiro de Ensaios Clinico (Brasilian National Registry) with the ID: RBR-2gycyv.

Acute Impact of Proprioceptive Exercise on Proprioception and Balance in Athletes

This study aimed to compare the acute effect of a proprioceptive exercise session and a non-specific exercise session on knee position sense, and the static and dynamic balance of athletes. Sixty male athletes (19.4 ± 1.2 years) participated in a within-subjects repeated-measures study. Knee position sense in closed kinetic chain, and static (BESS test) and dynamic balance (Y-balance test) were measured before and after two exercise sessions, consisting of 10 min of non-specific exercise in a cycle-ergometer or proprioceptive exercise with an unstable platform. Overall, both exercise sessions significantly improved knee position sense, BESS score, and YBT composite score, and no differences were detected between proprioceptive and non-specific sessions (knee position sense, −6.9 ± 65.2% vs. −11.5 ± 75.0%, p = 0.680; BESS, −19.3 ± 47.7% vs. −29.03 ± 23.5%, p = 0.121; YBT, 2.6 ± 2.7% vs. 2.2 ± 2.2%, p = 0.305). Twenty athletes did not improve knee position sense after the exercise session (non-responders). When analyzing only the exercise responders, both sessions improved knee position sense, but the improvement was greater after the proprioceptive exercise session (56.4 ± 25.6% vs. 43.8 ± 18.9%, p = 0.023). In conclusion, a single proprioceptive, as well as non-specific, exercise session increased knee position sense and balance. The proprioceptive exercise seems to be more effective in improving joint position sense when considering only athletes who respond to the intervention.

Proprioception and neuromuscular control at return to sport after ankle surgery with the modified Broström procedure

The modified Broström procedure (MBP) is an initial treatment for symptomatic chronic ankle instability (CAI) patients. This study aimed to compare the proprioception and neuromuscular control ability of both affected and unaffected ankles at the time of return to sports after MBP for patients with scores of normal controls. 75 individuals (40 who underwent MBP, 35 normal controls) participated. The dynamic balance test scores were significantly higher in the affected ankle of the patients than in the controls (1.5 ± 0.6° vs. 1.1 ± 0.4°, p < 0.003). The time to peak torque for dorsiflexion (60.8 ± 13.9 ms vs. 52.2 ± 17.5 ms, p < 0.022) and eversion (68.9 ± 19.1 ms vs. 59.3 ± 21.1 ms, p < 0.043) was significantly delayed in the affected ankle of the patients than in the controls. The dynamic balance test and time to peak torque in CAI patients remained significantly reduced at the time of return-to-sport after MBP. Clinicians and therapists should be aware of potential deficits in proprioception and neuromuscular control when determining the timing of return to sports after MBP.

Immediate effect of stabilization exercises versus conventional exercises of the trunk on dynamic balance among trained soccer players

Background: Trunk stability is key in controlling body balance and movements. Trunk Stabilization Exercises (TSE) and Conventional Trunk Exercises (CTE) are performed to improve dynamic balance. The authors have previously reported that dynamic balance was improved by a 12-week and 6-week TSE program. However, there is a dearth of research on its immediate effect on dynamic balance in trained soccer players. Objective: To compare the immediate effeect of TSE with that of CTE on dynamic balance in trained soccer players. Methods: Forty-eight male soccer players (24.60 ffi 1.38 years) participated in this crossover study, wherein each participant took part in three exercise sessions: TSE, CTE, and No Exercise control (NE), each consisting of three steps: pre-test, intervention and post-test, with an interval of one week between each exercise condition. To assess dynamic balance, the Y Balance Test-Lower Quarter (YBT-LQ) score in the anterior, posteromedial, and posterolateral directions was measured before and 5 minutes after each intervention. Results: The YBT-LQ composite score was significantly improved after TSE (0.51) as compared to CTE (0.22) and NE (0.04) (p < 0.05). Furthermore, in TSE and CTE conditions, YBT-LQ scores of the posterolateral and posteromedial directions significantly improved at the post-test (p < 0.05). Conclusions: Both TSE and CTE are effective in immediately improving dynamic balance; however, TSE showed greater improvement as compared to the latter. Immediate improvements in the posteromedial and posterolateral directions of the YBT-LQ were demonstrated after performing the TSE and CTE.

Ankle range of motion and dynamic balance in recreational Sepak Takraw players with and without ankle injury - a comparative study

Background and Study Aim. Sepak Takraw (ST) is considered Malaysia's national sport, and the nature of this sport requires players to be sufficiently acrobatic. Therefore, players were expected to jump and regain their balance, challenging their dynamic balance (DB). Nonetheless, range of motion (ROM) is closely related to balance. Hence, this study aimed to compare recreational ST players' ankle ROM and DB differences with and without ankle injuries. Material and Methods. The cross-sectional study in which 30 participants were assigned purposively according to players with an ankle injury (n=15) and without ankle injury (n=15) based on the position statement of the International Ankle Consortium (IAC). One time ankle Range of Motion and Dynamic balance was measured using a universal goniometer and Star Excursion Balance Test (SEBT), respectively, for both groups. Results. Independent T-test was performed to identify the significant differences (p<0.05) of SEBT and ROM between the non-injured leg and injured leg within the injured group to the non-injured group. Ankle eversion and dorsiflexion between the injured and non-injured groups did not show any significant difference with p=0.35 & p=0.53, respectively. As for SEBT, only posteromedial and medial of the injured leg did not show a significant difference p>0.05. All other ankles ROM and the SEBT score demonstrated a statistically significant difference p<0.05. Conclusions. ROM and DB training/rehabilitation should be incorporated to all the injured group ST sports players regardless of which leg is affected to optimize ankle function and the game performance.

The Effect of Sex, Sport Participation, and Concussion History on Baseline Concussion Balance Test Performance in Division-I Collegiate Athletes

ObjectiveExplore the effect of baseline characteristics such as sex, sport, and concussion history on the Concussion Balance Test (COBALT) performance in collegiate athletes.BackgroundThe COBALT is a recently developed clinical balance assessment specifically for athletic populations following concussion. The task conditions of the COBALT are designed to challenge sensory integration and reweighting processing underlying postural control. It has been documented that balance performance is influenced by factors such as sex and sport in collegiate athletes.Design/MethodsOne-hundred twenty seven collegiate athletes (77 male, 50 female; age: 19.81 ± 1.39; height: 68.77 ± 5.57 in; mass: 80.98 ± 26.15 kg), who participated in Division-I football, soccer, or cheerleading were included. Participants completed the 4 baseline conditions (Condition 3, 4, 7, 8) of the COBALT. Condition 3 (C3) included a side-to-side headshake with eyes closed. For Condition 4 (C4) the participant stood with hands clasped, elbows extended, and thumbs up while rotating their trunk side-to-side, visually focusing on their thumbs. Conditions 7 (C7) and 8 (C8) repeated C3 and C4 on a foam surface. Two 20-second trials of each condition were completed on a forceplate and the mean angular sway velocity (°/s) were calculated and number of errors were counted. ANOVAs and ANCOVAs were used to assess the potential effects on COBALT performance.ResultsThere were no significant differences in postural sway for any COBALT condition based on sex (p > 0.05). Females demonstrated more errors than males on C7 (p < 0.001). Cheerleaders had more balance errors compared to football athletes for C3 and C7 (p < 0.05) and soccer athletes for C7 (p < 0.05). Concussion history did not have an effect on COBALT performance (p > 0.05).ConclusionsUnderstanding factors that may influence COBALT performance at baseline may enhance concussion evaluation in collegiate athletes with suspected balance deficits following concussion. While concussion history had no effect, sex and sports participation may influence performance and should be considered when interpreting COBALT results post-concussion.

Thermal design and analysis of a flexible solar array system based on shape memory polymer composites

Smart structures based on shape memory polymer composites (SMPCs) have attracted extensive attention because of their unique self-deployment behavior. This study investigated the thermal design and analysis of the SMPC flexible solar array system (SMPC-FSAS). The thermal design ensured the reliability of the deployment functionality and desirable structural temperatures. The fundamental properties of the shape-memory materials were obtained by mechanical analysis (DMA) and shape fixity ratio tests. Thermal experiments, including the thermal balance test (TBT), thermal vacuum test (TVT) and thermal cycle test (TCT) were conducted to verify the safety and reliability of the SMPC-FSAS. Additionally, the temperature distribution of the SMPC-FSAS was simulated using numerical analysis. Notably, a geostationary satellite carrying the SMPC-FSAS was successfully launched into a geosynchronous orbit and controlled deployment was accomplished for the first time. The prediction of the numerical model was consistent with the TBT and on-orbit data, thus validating the accuracy of the numerical method. The research in this work has important reference significance for ultra-large SMPC-FSAS in the future.

Hip Flexibility and Dynamic Balance Ability in Soccer Players with Functional Ankle Instability

The prevention of recurrent ankle sprain and functional ankle instability in soccer players is essential. This study clarified hip joint mobility and dynamic balance ability in soccer players with functional ankle instability. This case–control study included 17 male college soccer players. All participants were assessed using the Cumberland Ankle Instability Tool and were divided into chronic ankle instability (CAI) and non-CAI groups for each of their dominant and nondominant legs. Bilateral passive hip range of motion (ROM) was assessed and the modified Star Excursion Balance Test (mSEBT) was measured for each leg. In the dominant leg, the reach in the posterolateral direction in the CAI group was significantly less than that in the non-CAI group. Hip internal rotation angles in the dominant leg in the CAI group were greater than those in the non-CAI group; however, no significant correlations with the three directions of mSEBT were observed. In the nondominant leg, mSEBT and hip ROMs did not show any significant differences between groups. The dominant leg in soccer players with CAI had poor dynamic balance ability while reaching posterolaterally. However, acquiring hip flexibility may not be necessary to improve the dynamic balance ability. These findings may help develop future research.

Efecto agudo del programa Knäkontroll sobre parámetros del rendimiento físico en jugadores de fútbol de categoría juvenil

El fútbol es un deporte que, por la alta exigencia física que requiere, lleva asociado un elevado riesgo de lesión. Dada la magnitud del problema, los investigadores han optado por diseñar estrategias preventivas que ayuden a minimizar la incidencia de lesión en este deporte. Estas estrategias se han organizado como programas de calentamiento previo a la participación en el deporte. Sin embargo, la evidencia sobre el efecto agudo de estas intervenciones sobre parámetros del rendimiento físico es escasa. Por tanto, el objetivo del presente estudio fue analizar el efecto agudo del programa Knäkontroll (nivel B) sobre parámetros del rendimiento físico en jugadores de fútbol de categoría juvenil. Para ello, se utilizó un diseño cuasi-experimental pre-test y post-test, empleando la estabilidad dinámica de la extremidad inferior (Y-Balance Test), la cinemática de la caída en salto vertical (Tuck Jump Assessment [TJA]), el rango de movimiento articular de la dorsiflexión de tobillo (ROM-Sport), la distancia de salto horizontal unilateral (Single-Legged Hop Tests), y la altura de salto vertical unilateral (Single Leg Countermovement Jump [SLCMJ]) como principales medidas del rendimiento físico. Los resultados mostraron un incremento significativo del rendimiento para todas las variables tras la implementación del programa Knäkontroll, a excepción de la altura en el SLCMJ y la cinemática en el TJA. En conclusión, el programa Knäkontroll se presenta como una estrategia adecuada para su aplicación como calentamiento previo a la práctica del fútbol. No obstante, la inclusión de ejercicios (o variantes) adicionales que trabajen el componente pliométrico podría contribuir a la mejora del desempeño en el salto vertical.