Muscle Quality Index is inversely associated with psychosocial variables among Chilean adolescents

Universidad de Las Américas under competitive research funds N° PI‑21–2022.A good muscle quality index (MQI) may have an inverse relationship with psychosocial variables of depression, anxiety, and stress in adolescents. Unfortunately, little scientific evidence has related MQI to psychosocial variables in this population. Therefore, this research aimed to determine the relationship between the MQI and psychosocial variables of depression, anxiety, and stress in Chilean adolescents. In this quantitative correlational design study, sixty adolescents participated voluntarily (mean ± standard deviation [SD]: age 15.11 ± 1.78 years). Anthropometric parameters, prehensile strength, MQI, and psychosocial variables were evaluated. The results showed that adolescents with high levels of MQI presented lower levels of depression (7.50 ± 6.06 vs. 10.97 ± 5.94), anxiety (5.64 ± 4.81 vs. 9.66 ± 5.12), and stress (6.79 ± 5.09 vs. 10 ± 5.58), in addition to reported lower abdominal obesity (WtHR, 0.47 ± 0.07 vs. 0.52 ± 0.07) than those with low levels of MQI. The group with high levels of MQI reported a higher prevalence of nonanxiety (81.3%, p = 0.031) and a lower prevalence of abdominal obesity (55.8%, p = 0.023). Likewise, a significant inverse association was evidenced between MQI and depression (β; -6.18, 95% CI; -10.11: -2.25, p = 0.003), anxiety (β; -6.61, 95% CI; -9.83: -3.39, p < 0.001) and stress (β; -4.90, 95% CI; -8.49: -1.32 p = 0.008). In conclusion, the results suggest that high levels of MQI are associated with a higher prevalence of nonanxiety in adolescents and a significant inverse association between MQI and levels of depression, anxiety, and stress.Universidad de Las Américas, Chile N° PI‑21–202

Efectos del entrenamiento en slackline sobre la resistencia del core y el equilibrio dinámico

Slackline challenges balance by walking on a tensioned strap, where the trunk muscles help to maintain or regain balance. This study aimed to compare a cohort of individuals who regularly practiced slackline and physically inactive individuals on core endurance (CE) and dynamic balance (DB) and to determine whether CE is associated with years of slackline practice. Nine individuals (7 men) who practiced slackline regularly (SG; age= 24.5±3.6 years) and nine physically inactive individuals (7 men) (CG; age= 23.2±3.3 years) were compared. CE was assessed with the McGill battery (trunk flexor, extensor, and side-bridge test) and the plank test. DB was measured with the modified star excursion balance test in stable and unstable conditions. The SG maintained a 36.2% and 45% longer time in left lateral bridge (p=.049) and plank (p=.031), respectively, compared to the CG. The distance achieved in the stable DB test was similar between groups, but in unstable condition was 37.8% greater (p=.016) in SG in both legs and 46.6% greater in the non-dominant leg (p=.039) compared to CG. The SG showed a correlation between years of slackline practice and flexor (r=.674; p=.046), right lateral (r=.765; p=.016) and left (r=.730; p=.026) trunk endurance. In conclusion, those who practice slackline maintain a longer time in the plank and left lateral bridge test and achieve a higher reach distance in unstable DB compared to physically inactive individuals who do not practice slackline.El slackline desafía el equilibrio al caminar sobre una cinta en tensión, donde los músculos del tronco ayudan a mantener o recuperar el equilibrio. El objetivo de este estudio fue comparar individuos que practicaban slackline e individuos inactivos fisicamente (IF) en resistencia del core (RC) y equilibrio dinámico (ED), y conocer si la RC se asocia a los años de practica de slackline. Nueve individuos (7 hombres) que practicaban slackline regularmente (GS; edad= 24.5±3.6 años) y nueve individuos IF (7 hombres) (GC; edad= 23.2±3.3 años) fueron comparados. La RC se evaluó con la bateria de McGill (prueba de flexores y extensores de tronco y puente lateral) y la prueba de la plancha. El ED se midió con la prueba de excursión de la estrella modificada en condiciones estables e inestables. El GS mantuvo un tiempo 36.2% y 45% mayor en puente lateral izquierdo (p=.049) y plancha (p=.031) respectivamente comparado con el GC. La distancia alcanzada en la prueba de ED estable fue similar entre grupos, pero en condición inestable fue 37.8% mayor (p=.016) en GS en ambas piernas y 46.6% mayor en la pierna no dominante (p=.039) comparado al GC. El GS mostró una correlación entre años de práctica de slackline y resistencia flexora (r=.674; p=.046), lateral derecha (r=.765; p=.016) e izquierda (r=.730; p=.026) de tronco. En conclusión, quienes practican slackline mantienen un tiempo mayor la prueba de la plancha y puente lateral izquierdo y logran un mayor alcance en ED inestable comparados con individuos IF que no lo practican

Effect of sit-to-stand-based training on muscle quality in sedentary adults: a randomized controlled trial

The aim of this study was to compare the effects of sit-to-stand (STS) training programs with 5 vs. 10 repetitions on muscle architecture and muscle function in sedentary adults. Sixty participants were randomly assigned into three groups: five-repetition STS (5STS), 10-repetition STS (10STS), or a control group (CG). Participants performed three sets of five or 10 repetitions of the STS exercise three times per week for 8 weeks. Before and after 8 weeks, all groups performed ultrasound measures to evaluate muscle thickness (MT), pennation angle (PA), and fascicle length (FL), and the five-repetition STS test to estimate the relative STS power and muscle quality index (MQI). After 8 weeks, both experimental groups improved MQI (40–45%), relative STS power (29–38%), and MT (8–9%) (all p < 0.001; no differences between the 5STS vs. 10STS groups). These improvements in both groups resulted in differences regarding the CG, which did not present any change. In addition, only the 5STS group improved PA (15%; p = 0.008) without differences to the 10STS and CG.This suggests that STS training is time-effective and low-cost for improving muscle function and generating adaptations in muscle architectureRecualificación del Profesorado Universitario. Modalidad Margarita Salas”, Universidad de Granada/ Ministerio de Universidades y Fondos Next Generation de la Unión Europe

Efectos de diferentes protocolos de fortalecimiento de miembro inferior sobre la fuerza, potencia y actividad muscular en sujetos sedentarios y físicamente inactivos: una revisión sistemática

The purpose of this systematic review was: a) to determine the quality of evidence from studies assessing the effects of different lower limb strengthening protocols on muscle activity, strength, and power in sedentary and/or physically inactive subjects; and b) to determine the effectiveness of lower extremity strengthening protocols on muscle activity, strength, and power in sedentary and/or physically inactive subjects. Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) statements were followed using keywords associated with strength training, lower limb, sedentary, and physical inactivity. Four databases were used: Medline via PubMed, Web of Science, Scopus and SPORTDiscus. Methodological quality was assessed using the PEDro scale. A total of 164 articles were retrieved, six included in this review. Four studies were classified as fair methodological quality, and two were considered of good methodological quality. Due to the heterogeneity in methodological aspects and the limited number of articles including the variables under study, it was not possible to establish a measure of effectiveness of lower limb strengthening protocols on muscle activity, strength, or power. In conclusion, strength training in the lower limb seems to improve the levels of strength, power, and muscular activity in sedentary subjects. However, due to the limited number of articles, methodological variability, and training methods used, it is necessary to conduct new studies that control these variables.El propósito de esta revisión sistemática fue: a) determinar la calidad de la evidencia de los estudios que evaluaron los efectos de diferentes protocolos de fortalecimiento de miembros inferiores sobre la actividad, la fuerza y la potencia muscular en sujetos sedentarios y/o físicamente inactivos; y b) determinar la efectividad de los protocolos de fortalecimiento sobre la actividad, fuerza y potencia muscular de miembros inferiores en sujetos sedentarios y/o físicamente inactivos. Se siguieron los criterios PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analyse) utilizando palabras clave asociadas con el entrenamiento de fuerza, extremidades inferiores, sedentarismo e inactividad física. Se revisaron cuatro bases de datos: Medline vía PubMed, Web of Science, Scopus y SPORTDiscus. La calidad metodológica se evaluó mediante la escala PEDro. Se recuperaron 164 artículos en total, seis incluidos en esta revisión. Cuatro estudios se clasificaron como de calidad metodológica regular y dos se consideraron de buena calidad metodológica. Debido a la heterogeneidad en los aspectos metodológicos y al escaso número de artículos que incluyeron las variables en estudio, no fue posible establecer una medida de efectividad de los protocolos de fortalecimiento de miembros inferiores sobre la actividad, la fuerza o la potencia muscular. En conclusión, el entrenamiento de fuerza en el miembro inferior parece mejorar los niveles de fuerza, potencia y actividad muscular en sujetos sedentarios. No obstante, debido al número limitado de artículos, la variabilidad metodológica y los métodos de entrenamiento utilizados, es necesario realizar nuevos estudios que controlen estas variables

Muscle Quality and Functional and Conventional Ratios of Trunk Strength in Young Healthy Subjects: A Pilot Study

Background: The trunk strength conventional ratio (CR) has been evaluated. However, the functional ratio and the ratio of strength to body weight (BW) or muscle mass (MM) have been poorly explored. Relative strength is a measure of muscle quality. Objectives: To analyze the trunk strength ratio normalized by BW and MM and compare the trunk's conventional and functional ratios collected in isokinetic and isometric conditions. Methods: Twenty-seven healthy males (21.48 +/- 2.08 years, 70.22 +/- 7.65 kg) were evaluated for trunk isometric and isokinetic strength using a functional electromechanical dynamometer. Results: The extensor's strength was greater than the flexors, with a CR of 0.41 +/- 0.10 to 0.44 +/- 0.10. Muscle quality was higher in eccentric contraction and high velocity for flexors and extensors. The functional flexor ratio (FFR) ranged between 0.41 +/- 0.09 and 0.92 +/- 0.27. The functional extensor ratio (FER) ranged between 2.53 +/- 0.65 and 4.92 +/- 1.26. The FFR and FER showed significant differences between velocities when considering the peak strength (p = 0.001) and mean strength (p = 0.001). Conclusions: Trunk extensors were stronger than the flexors; thus, the CR was less than one. Muscle quality was higher at a high velocity. Unlike CR, FFR and FER behaved differently at distinct velocities. This finding highlights the need to explore the behavior of the functional ratio in different populations.DGI-University Andres Bello DI-08-CBC/22FEDER/Ministry of Science, Innovation, and Universities-State Research Agency RTI2018-099723-B-I0

Changes in Muscle Oxygen Saturation Measured Using Wireless Near-Infrared Spectroscopy in Resistance Training: A Systematic Review

This work was supported by DGI-University Andres Bello, No DI-6-20/CBC.This paper will be part of Claudia Miranda-Fuentes’ Doctoral Thesis performed in the Biomedicine Doctorate Program of the University of Granada.Background: This study aimed to report, through a systematic review of the literature, the baseline and final reference values obtained by near-infrared spectroscopy (NIRS) of muscle oxygen saturation (SmO2) during resistance training in healthy adults. Methods: Original research studies were searched from four databases (Scopus, PubMed, WOS, and SportDiscus). Subsequently, three independent reviewers screened the titles and abstracts, followed by full-text reviews to assess the studies' eligibility. Results: Four studies met the inclusion criteria, data were extracted and methodological quality was assessed using the Downs and Black scale. Muscle oxygen saturation (% SmO2) during reported muscle strength exercises showed a decreasing trend after a muscle strength protocol; that is, before the protocol (range = 68.07-77.9%) and after (range = 9.50-46.09%). Conclusions: The trend of the SmO2 variables is to decrease after a muscle strength protocol. Studies are lacking that allow expanding the use of these devices during this type of training.DGI-University Andres Bello DI-6-20/CB

Exploration of the Shoulder Internal Rotation’s Influence on Throwing Velocity in Handball Players: A Pilot Study

The main objective of this study was to test the relationship between shoulder internal rotation strength and standing throwing velocity. A repeated measures cross-sectional study was conducted with 20 professional handball players (mean +/- SD; age: 19.28 +/- 2.55 years, weight: 81.52 +/- 9.66 kg, height: 185 +/- 6 cm, BMI: 23.74 +/- 1.69). The participants were instructed to perform eight standing throws from the 7 m line of the handball court at maximum velocity to calculate the mean and maximum throwing velocity. An incremental test was performed to calculate the repetition maximum (1-RM) of internal rotation shoulder strength. A Pearson's correlation analysis with a 95% confidence interval (95% CI) was performed to determine whether correlations existed between dominant arm internal rotation strength characteristics and maximum and mean ball-throwing velocity. There is no correlation between the internal rotation strength of the throwing shoulder and the velocity of the ball in the standing handball throw.FEDER/Junta de Andalucia- Consejeria de Transformacion Economica, Industria, Conocimiento y UniversidadesEuropean Commission B-CTS-184-UGR2

Test-retest reliability of a functional electromechanical dynamometer on swing eccentric hamstring exercise measures in soccer players

This study was supported by FEDER/Ministry of Science, Innovation and UniversitiesState Research Agency (Dossier number: RTI2018-099723-B-I00). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Background: The use of a functional electromechanical dynamometer (FEMD) has been proposed as a valid and effective tool to evaluate specific movement patterns. The aim of this study was to determine the reliability of FEMD on swing eccentric hamstring exercise (SEHE) measures in soccer players. Methods: Nineteen federated male soccer players (20.74 ± 4.04 years) performed the SEHE at three different isokinetic velocities (20–40–60 cm/s). These evaluations were conducted in four sessions, two for familiarization and two for registration. The average and maximum load (N) of the three isokinetic velocities was calculated from the values obtained from the FEMD (Dynasystem , Bangalore). Results: The main results of this research showed that the reliability was high for the average load in the condition of 40 cm/s, presenting the highest ICC value (0.94). For maximum load, reliability was high in the condition of 20 cm/s. The manifestation of the most reliable load was the maximum load (ICC = 0.91–0.87). Conclusions: FEMD (Dynasystem , Bangalore) is a reliable device to evaluate the eccentric strength of the hamstring muscles in soccer players.FEDER/Ministry of Science, Innovation and UniversitiesState Research Agency RTI2018-099723-B-I0

Males Have a Higher Energy Expenditure than Females during Squat Training

This paper will be part of Indya del-Cuerpo's Doctoral thesis performed in the Biomedicine Doctorate Program of the University of Granada, Spain, through the funding of the Spanish Ministry of Universities under Grant FPU19/02030. The postdoctoral researcher Pedro Delgado-Floody has a contract through the program "Recualificacion del Profesorado Universitario. Modalidad Maria Zambrano", Universidad de Granada/Ministerio de Universidades y Fondos Next Generation de la Union Europea. The postdoctoral researcher Daniel Jerez-Mayorga has a contract through the program "Recualificacion del Profesorado Universitario. Modalidad Margarita Salas", Universidad de Granada/Ministerio de Universidades y Fondos Next Generation de la Union Europea. This study was supported by the High Council for Sports (CSD)and the Spanish Ministry of Culture and Sports through the "Network of Sports Functional Dynamometry" (09/UPB/23) and the NESA NETWORK "Spanish Network of Sports Care at Altitude" (19/UPB/23).The main objective of this study was to determine the differences in energy expenditure (EE) according to sex during and after two different squat training protocols in a group of healthy young adults. Twenty-nine Sports Sciences students volunteered to participate in this study. They attended the laboratory on four different days and completed four sessions: two sessions with 3 sets of 12 repetitions at 75% of their one-repetition maximum (RM) and two sessions with 3 sets of 30 repetitions at 50% of their 1RM. Energy expenditure was evaluated using an indirect calorimeter. Males consistently demonstrated higher EE in all sessions and intensities. The linear regression model identified a significant association between sex, BMI, and total EE across all sessions and intensities. In conclusion, males exhibited higher EE in both protocols (50% and 75% of 1RM) throughout all sessions. Furthermore, sex and BMI were found to influence EE in healthy young adults. Therefore, coaches should consider sex when assessing EE, as the metabolic response differs between males and females.University of Granada, Spain through Spanish Ministry of UniversitiesSpanish Government 09/UPB/23High Council for Sports (CSD)Spanish Ministry of Culture and Sports through the "Network of Sports Functional Dynamometry" FPU19/02030NESA NETWORK "Spanish Network of Sports Care at Altitude"19/UPB/2

Test–Retest Reliability of Functional Electromechanical Dynamometer on Five Sit-to-Stand Measures in Healthy Young Adults

Background: The purpose of this study was to determine the reliability for the strength and movement velocity of the concentric phase from the five Sit-to-Stand (5STS), using three incremental loads measured by a functional electromechanical dynamometer (FEMD) in healthy young adults. Methods: The average and peak strength and velocity values of sixteen healthy adults (mean ± standard deviation (SD): age = 22.81 ± 2.13 years) were recorded at 5, 10 and 15 kg. To evaluate the reliability of FEMD, the intraclass correlation coefficient (ICC), standard error of measurement (SEM) and coefficient of variation (CV) were obtained. Results: Reliability was high for the 10 kg (CV range: 3.70–4.18%, ICC range: 0.95–0.98) and 15 kg conditions (CV range: 1.64–3.02%, ICC: 0.99) at average and peak strength, and reliability was high for the 5 kg (CV range: 1.71–2.84%, ICC range: 0.96–0.99), 10 kg (CV range: 0.74–1.84%, ICC range: 0.99–1.00) and 15 kg conditions (CV range: 0.79–3.11%, ICC range: 0.99–1.00) at average and peak velocity. Conclusions: The findings of this study demonstrate that FEMD is a reliable instrument to measure the average and peak strength and velocity values during the five STS in healthy young adults.FEDER/Ministry of Science, Innovation and Universities—State Research Agency (Dossier number: RTI2018-099723-B-I00