Reliability of Dynamic Shoulder Strength Test Battery Using Multi-Joint Isokinetic Device.

This study aimed to determine the absolute and relative reliability of concentric and eccentric flexion, extension, horizontal abduction, and adduction movements of the shoulder using a functional electromechanical dynamometer (FEMD). Forty-three active male university students (23.51 ± 4.72 years) were examined for concentric and eccentric strength of shoulder flexion, extension, horizontal abduction, and horizontal adduction with an isokinetic test at 0.80 m·s-1. Relative reliability was determined by intraclass correlation coefficients (ICCs) with 95% confidence intervals. Absolute reliability was quantified by the standard error of measurement (SEM) and coefficient of variation (CV). Reliability was very high to extremely high for all movements on concentric and eccentric strength measurements (ICC: 0.76-0.94, SEM: 0.63-6.57%, CV: 9.40-19.63%). The results of this study provide compelling evidence for the absolute and relative reliability of concentric and eccentric flexion, extension, horizontal abduction, and horizontal adduction shoulder isokinetic strength tests in asymptomatic adults. The mean concentric force was the most reliable strength value for all tests.

Test-Retest Reliability of 3 Specific Strength Tests in Professional Handball Players.

CONTEXT: Current devices to assess strength performance in handball may not be sufficiently sports-specific and reliable methods. Functional electromechanical dynamometry is a new technology that allows the development of accurate strength tests in athletes. PURPOSE: To determine the absolute and relative reliability and to compare the reliability of the right and left side, and mean and peak force of 3 specific strength tests in handball players with a functional electromechanical dynamometer: unilateral pullover, standing lift, and step forward. METHODS: Fourteen male handball players of the first Spanish division (28.79 [4.81] y; 10.38 [4.63] y of professional experience) performed a repeated-measurement design. Three testing sessions were performed (one per week). The first measurement consisted of 4 isometric tests (right and left unilateral pullover, and right and left standing lift) to obtain isometric peak force, and in the second and third sessions, 6 incremental tests until failure (right and left unilateral pullover, and right and left standing lift, right and left step forward) were performed. RESULTS: The tests provided high reliability or acceptable reliability for mean and peak strength of unilateral pullover, standing lift and step forward (intraclass correlation coefficient = .83-.97; coefficient of variation = 3.90-11.57). Effect side was negligible in any of the parameters, except for a small effect side in the left peak force for unilateral pullover and a small effect side on the left side for a step forward. Significant differences in reliability (coefficient of variation ratio > 1.15) were found between the right and left sides and peak and mean force in all exercises except peak force in unilateral pullover and step forward. CONCLUSION: These results confirm that the tests could be applied to assess physical performance in handball at the same time as regular gym training. Moreover, this is an excellent opportunity to individualize the player's weekly load.

Effects of Power Training on Functional Capacity Related to Fall Risk in Older Adults: A Systematic Review and Meta-analysis.

OBJECTIVE: Functional capacity is 1 of the main risk factors for falls among older adults. The aim of this systematic review and meta-analysis was to determine the effect of power training on functional capacity test (FCT) related to fall risk in older adults. DATA SOURCES: Systematic searches were conducted in 4 databases, including PubMed, Web of Science, Scopus, and SPORTDiscus, from inception to November 2021. STUDY SELECTION: Randomized controlled trials (RCTs) assessing the effect of power training on functional capacity compared with another type of training program or control group in older adults with the ability to exercise independently. DATA EXTRACTION: Two independent researchers evaluated eligibility and used the PEDro scale to assess risk of bias. The information extracted was related to article identification (authors, country and year of publication), participant characteristics (sample, sex, and age), strength training protocols (exercises/intensity/weeks), and the outcome of the FCT used related to fall risk. The Cochran Q statistic and I2 statistics was used to assess heterogeneity. Random-effects model were conducted to pool the effect sizes expressed as mean differences (MD). DATA SYNTHESIS: Twelve studies (478 subjects) were selected for systematic review. A meta-analysis comprised 6 studies (217 subjects) where the outcome measure was the 30-second Sit to Stand (30s-STS) test, and another comprised 4 studies (142 subjects) where the outcome measure was the timed Up and Go (TUG) test. There was an improvement in performance in favor of the experimental group in both the TUG subgroup (MD -0.31 s; 95% CI -0.63, 0.00 s; P=.05), and the 30s-STS subgroup (MD 1.71 reps; 95% CI -0.26, 3.67 reps; P=.09). CONCLUSIONS: In conclusion, power training increases functional capacity related to fall risk further than other types of exercise in older adults.

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

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 (ß; -6.18, 95% CI; -10.11: -2.25, p = 0.003), anxiety (ß; -6.61, 95% CI; -9.83: -3.39, p < 0.001) and stress (ß; -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.

Impact of Starting Knee Flexion Angle on Muscle Activity and Performance during Plyometrics without Jumping.

Most of the existing research has focused on jump plyometrics, where landing reaction forces must be dissipated among lower limb articulations. In contrast, the investigation of resisted plyometrics without jumping, devoid of such landing forces, remains relatively limited. This study aimed to (i) investigate the impact of resisted plyometrics without jumping at two knee flexion angles (60 and 90 degrees) on vastus muscle activity relative to limb dominance and (ii) assess strength, power, and work during the concentric-eccentric phases of these exercises. Thirty-one healthy participants underwent quantification of lower limb muscle amplitude, strength, power, and work during resisted plyometrics without jumping from both 60° and 90° knee flexion positions. After anthropometric evaluations, participants used a dynamometer with a load equal to 80% of body weight while wireless surface electromyography electrodes recorded data. Statistical analyses utilized paired t-tests or nonparametric equivalents and set significance at p ≤ 0.05. Results showed significantly higher muscle activity in the vastus medialis (VM) (dominant: 47.4%, p = 0.0008, rs = 0.90; nondominant: 54.8%, p = 0.047, rs = 0.88) and vastus lateralis (VL) (dominant: 46.9%, p = 0.0004, rs = 0.86; nondominant: 48.1%, p = 0.021, rs = 0.67) muscles when exercises started at 90° knee flexion, regardless of limb dominance. Substantial intermuscle differences occurred at both 60° (50.4%, p = 0.003, rs = 0.56) and 90° (54.8%, p = 0.005, rs = 0.62) knee flexion, favoring VM in the nondominant leg. Concentric and eccentric strength, power, and work metrics significantly increased when initiating exercises from a 90° position. In conclusion, commencing resisted plyometrics without jumping at a 90° knee flexion position increases VM and VL muscle activity, regardless of limb dominance. Furthermore, it enhances strength, power, and work, emphasizing the importance of knee flexion position customization for optimizing muscle engagement and functional performance.

The Role of the Specific Strength Test in Handball Performance: Exploring Differences across Competitive Levels and Age Groups.

The aim of this study was to determine if specific physical tests are sufficiently discriminant to differentiate players of similar anthropometric characteristics, but of different playing levels. Physical tests were conducted analyzing specific strength, throwing velocity, and running speed tests. Thirty-six male junior handball players (n = 36; age 19.7 ± 1.8 years; 185.6 ± 6.9 cm; 83.1 ± 10.3 kg; 10.6 ± 3.2 years of experience) from two different levels of competition participated in the study: NT = 18 were world top-level elite players, belonging to the Spanish junior men's national team (National Team = NT) and A = 18 players of the same age and anthropometric conditions, who were selected from Spanish third league men's teams (Amateur = A). The results showed significant differences (p < 0.05) between the two groups in all physical tests, except for two-step-test velocity and shoulder internal rotation. We conclude that a battery combining the Specific Performance Test and the Force Development Standing Test is useful in identifying talent and differentiating between elite and sub-elite players. The current findings suggest that running speed tests and throwing tests are essential in selecting players, regardless of age, sex, or type of competition. The results shed light on the factors that differentiate players of different levels and can help coaches in selecting players.

Vertical Versus Horizontal Training for Improving the Change of Direction Speed in Adult Basketball Players: A Systematic Review and Meta-analysis.

ABSTRACT: Barrera-Domínguez, FJ, Martínez-García, D, Jerez-Mayorga, D, Chirosa-Ríos, LJ, Almagro, BJ, and Molina-López, J. Vertical versus horizontal training for improving the change of direction speed in adult basketball players: a systematic review and meta-analysis. J Strength Cond Res XX(X): 000-000, 2023-The ability to perform changes of direction (COD) is a complex skill that involves the application of multiple force-orientations, and its execution at maximum speed is crucial in basketball players. The present study aimed to synthesize findings from previous interventions classified according to force-orientation (vertical, horizontal, or mixed) and determine their magnitude of the effect on COD performance in basketball players. A systematic review of the literature was performed in several databases (Web of Science, Scopus, SPORTDiscus, and PubMed) following the PRISMA statement and reviewed the quality of the included papers according to the Cochrane Collaboration Guidelines Assessment. Sixteen articles with a total of 21 reports were included to analyze the role of force-orientations in COD performance. For the meta-analysis, the standardized mean differences with 95% confidence intervals (CIs) were calculated to determine the chronic changes induced by training and performed an effect size (ES) analysis with a random-effects model. The results showed that all force-orientations generated improvements in COD performance (ES = -0.47 [95% CI -0.57, -0.36], Z = 8.74 [p < 0.01]). It was a mixed force-orientation that produced the greatest changes (ES = -0.91 [95% CI -1.27, -0.55], Z = 4.96 [p < 0.01]), followed by vertical training (ES = -0.45 [95% CI -0.70, -0.20], Z = 3.51 [p < 0.01]). Horizontal training was the least studied and showed the smallest change (ES = -0.10 [95% CI -0.14, -0.07], Z = 5,71 [p < 0.01]). This meta-analysis demonstrates that mixed vertical and horizontally oriented training may be the most optimal because it offers a greater variety of multidirectional stimuli that better prepares the athlete to deal with complex COD in real-game situations.

On-court throwing activity of male handball players during the European Championship 2020.

The aim of this study was to investigate the on-court throwing activity in regards to playing positions, throwing zones on the court and throwing velocity category during the male European Championship 2020. A local positioning system with microsensors placed both in the shirts of the players and inside the ball itself was used. In total, 6568 throws were retrieved for analysis from the entire tournament. Results showed that first-line players (wings and line players) used their natural zone more to throw (65% left wing, 60% right wing, and 97% line player), showing higher effectiveness from there (p < 0.05). Second lines players distributed more of their throws (45% left back, 50% right back and 32% center back in their natural zones) giving priority to the throws in 6 m, where they showed higher effectiveness (p < 0.05), or between the lines. Considering all players, shots from nearby and intermediate areas corresponded to 83% of the shots showing higher efficiency (p < 0.05) than shots performed from the areas furthest from the goal (14.9%. from zones 6-7-8). Back players mainly performed the highest velocity throws (Category 4 > ~100 km/h) from these furthest areas. Throwing velocity and effectiveness by throwing zones and positions was not significantly modified over the three rounds of the tournament (p > 0.05), indicating no effect of possible fatigue. A higher team ranking was associated with higher throwing efficiency but only for wing players. The results of this research could help handball coaches to better adjust training programs for the improvement of throwing velocity and its transfer to the competition.

Core training and performance: a systematic review with meta-analysis.

The purposes were to synthesize as much scientific evidence as possible to determine the effect of core training on balance, throwing/hitting velocity or distance, and jumping in healthy subjects, identify the possible differences between isolated and combined core training on performance and study training and sample variables related to performance. PRISMA guidelines were followed, and a systematic search was performed in the Scopus, Web of Science, Sports Discuss, and PubMed databases with no date restrictions until November 2022. The studies were considered for this meta-analysis following PICO; a) randomized control trials and randomized allocation studies with healthy subjects and > 12 years old b)isolated or combined core training programs with a minimum of 4 weeks in length; c) athletic performance outcomes for balance, throw/hit, and jump variables should be measured; d) sufficient data to calculate effect sizes. The Cochrane Collaboration Risk of Bias Tool and the Grading of Recommendations Assessment, Development, and Evaluation approach were used for assessing methodological quality. A total of 3223 studies were identified, 22 studies were included in the systematic review and 21 for the meta-analysis. We observed that core training improved balance outcomes (ES = 1.17; p < 0.0001), throwing/hitting velocity (ES = 0.30; p = 0.14), throwing/hitting distance (ES = 3.42; p = 0.03), vertical jumping (ES = 0.69; p = 0.0003), and horizontal jump (ES = 0.84; p = 0.01). Our findings indicate that core training improved different variables of performance such as balance, throw/hit, and vertical and horizontal jump.

Throwing performance by playing positions of male handball players during the European Championship 2020.

The aim of this study was to analyze the throwing velocity and effectiveness of elite male handball players during the European Championship 2020. A local positioning system was used for the first time in a European Championship to collect 6568 throw events from 337 players of 24 national teams during 65 matches. ANOVA (F = 80.8, p < 0.01, η2  = 0.058) revealed that back players throws were significantly faster (24.3-26.5 m/s) than the rest of the players (22.2-22.5 m/s). Similarly, throws made from the central zone showed the highest speed values of 28.0 m/s (F = 43.2, p < 0.01, η2  = 0.050). In regard to the goal hit zone, higher speeds were shown for throws in side zones (24.9-26.8 m/s) compared to central zones (23.0-23.8 m/s) (F = 49.0, p < 0.01, η2  = 0.063). Effectiveness was higher in wing players (62%-64%) than the rest (45%-56%) (F = 30.9, p < 0.01, η2  = 0.023). Interestingly, the two higher velocity categories (>22 m/s) showed similar effectiveness (~60%), which were higher than the preceding slower category of 17-22 m/s (39.7%) (F = 175.1, p < 0.01, η2  = 0.074). Regarding court zones, throws from first-line zones (48%-60%), were more effective than from second line (38%-43%) (F = 13.1, p < 0.01, η2  = 0.016). With respect to the goal hit zone, effectiveness was higher in side (72%-77%) than in central zones (58%-64%) (F = 523.2, p < 0.01, η2  = 0.418). Coaches should improve the throwing velocity of players but also train at submaximal velocities (effective velocity) to save energy and reduce the potential risk of injury. Finally, training should be specialized according to the performance shown by players from different throwing zones, rather than from playing positions.

Effect of Traditional, Cluster, and Rest Redistribution Set Configurations on Neuromuscular and Perceptual Responses During Strength-Oriented Resistance Training.

ABSTRACT: Cuevas-Aburto, J, Jukic, I, Chirosa-Ríos, LJ, González-Hernández, JM, Janicijevic, D, Barboza-González, P, Guede-Rojas, F, and García-Ramos, A. Effect of traditional, cluster, and rest redistribution set configurations on neuromuscular and perceptual responses during strength-oriented resistance training. J Strength Cond Res 36(6): 1490-1497, 2022-This study aimed to compare the acute effect of traditional (TR), cluster (CL), and rest redistribution (RR) set configurations on neuromuscular and perceptual measures of fatigue. Thirty-one resistance-trained men randomly performed a Control session and 3 experimental sessions consisting of the squat (SQ) and bench press (BP) exercises performed against the 10 repetition maximum load using TR (3 sets of 6 repetitions; 3 minutes of interset rest), CL (3 sets of 6 repetitions; 30 seconds of intraset rest every 2 repetitions; 3 minutes of interset rest), and RR (9 sets of 2 repetitions; 45 seconds of interset rest) set configurations. A significant effect of "set configuration" (p = 0.002) was observed for barbell velocity. The average velocity of the training session was lower for TR compared with CL (% difference = 5.09% in SQ and 5.68% in BP) and RR (% difference = 5.92% in SQ and 2.71% in BP). The 3 set configurations induced comparable decrements in countermovement jump height (% difference from -6.0% to -8.1%) and throwing velocity (% difference from -0.6% to -1.2%). Ratings of perceived exertion (RPE-10) values collected after the sets were higher for TR (SQ: 6.9 ± 0.7 a.u.; BP: 6.8 ± 0.8 a.u.) compared with CL (SQ: 6.2 ± 0.8 a.u.; BP: 6.4 ± 0.7 a.u.) and RR (SQ: 6.2 ± 0.8 a.u.; BP: 6.6 ± 0.9 a.u.), while the session RPE did not differ between the set configurations (p = 0.595). CL and RR set configurations allow for higher velocities and lower RPE values during resistance training sessions not performed to failure in comparison with a TR set configuration.

Effects of post-tetanic potentiation induced by whole-body electrostimulation and post-activation potentiation on maximum isometric strength.

It is currently unknown the most effective potentiation protocol to increase maximum strength. Hence, we investigated the separated and combined effects of post-tetanic potentiation (PTP) induced by whole-body electrostimulation (WB-EMS) and post-activation potentiation (PAP) induced by voluntary maximum isometric contractions on maximum isometric strength. Ten trained males were randomly evaluated on four occasions. In session A, maximum isometric strength (split squat) was measured in minutes 1, 4, and 8. In session B, the measurements were taken in minutes 2, 6, and 10. In session C, a WB-EMS protocol was applied to elicit PTP and the measurements were performed in minutes 1, 4, and 8. In session D, the same WB-EMS protocol was applied and the measurements were taken in minutes 2, 6, and 10. No significant differences in maximum isometric strength were observed between: (i) the control and WB-EMS in minutes 1 vs. 1 and 2 vs. 2; (ii) the control and PAP in minutes 1 vs. 4, 1 vs. 8, 2 vs. 6, and 2 vs. 10; and (iii) the PAP and WB-EMS plus PAP in minutes 4 vs. 4, 8 vs. 8, 6 vs. 6, and 10 vs. 10. In contrast, the WB-EMS plus PAP revealed a significant increase of 54% (~450 N) compared to the WB-EMS in minutes 4 and 8 compared to the minute 1 (p < 0.001), but not between minutes 2 vs. 6 and 2 vs. 10. The present results showed that PTP induced by WB-EMS in isolation or combined with PAP induced by voluntary maximum isometric contractions did not produce a significant increase in maximum isometric strength compared to the control and PAP alone, respectively.

Reliability and validity of different methods of estimating the one-repetition maximum during the free-weight prone bench pull exercise.

This study examined the reliability and validity of three methods of estimating the one-repetition maximum (1RM) during the free-weight prone bench pull exercise. Twenty-six men (22 rowers and four weightlifters) performed an incremental loading test until reaching their 1RM, followed by a set of repetitions-to-failure. Eighteen participants were re-tested to conduct the reliability analysis. The 1RM was estimated through the lifts-to-failure equations proposed by Lombardi and O'Connor, general load-velocity (L-V) relationships proposed by Sánchez-Medina and Loturco and the individual L-V relationships modelled using four (multiple-point method) or only two loads (two-point method). The direct method provided the highest reliability (coefficient of variation [CV] = 2.45% and intraclass correlation coefficient [ICC] = 0.97), followed by the Lombardi's equation (CV = 3.44% and ICC = 0.94), and no meaningful differences were observed between the remaining methods (CV range = 4.95-6.89% and ICC range = 0.81-0.91). The lifts-to-failure equations overestimated the 1RM (3.43-4.08%), the general L-V relationship proposed by Sánchez-Medina underestimated the 1RM (-3.77%), and no significant differences were observed for the remaining prediction methods (-0.40-0.86%). The individual L-V relationship could be recommended as the most accurate method for predicting the 1RM during the free-weight prone bench pull exercise.

[Association between physical fitness parameters and health related quality of life in Chilean community-dwelling older adults]. / Asociación predictiva entre parámetros de condición física y dimensiones de calidad de vida relacionada con la salud en adultos mayores chilenos insertos en la comunidad.

BACKGROUND: There is no conclusive evidence about the association between physical fitness (PF) and health related quality of life (HRQOL) in older adults. AIM: To seek for an association between PF and HRQOL in non-disabled community-dwelling Chilean older adults. MATERIAL AND METHODS: One hundred and sixteen subjects participated in the study. PF was assessed using the Senior Fitness Test (SFT) and hand grip strength (HGS). HRQOL was assessed using eight dimensions provided by the SF-12v2 questionnaire. Binary multivariate logistic regression models were carried out considering the potential influence of confounder variables. RESULTS: Non-adjusted models, indicated that subjects with better performance in arm curl test (ACT) were more likely to score higher on vitality dimension (OR > 1) and those with higher HGS were more likely to score higher on physical functioning, bodily pain, vitality and mental health (OR > 1). The adjusted models consistently showed that ACT and HGS predicted a favorable perception of vitality and mental health dimensions respectively (OR > 1). CONCLUSIONS: HGS and ACT have a predictive value for certain dimensions of HRQOL.

[Effects of small-sided exercises on body composition and maximal oxygen uptake in adolescents]. / Efecto de los juegos reducidos en la composición corporal y la condición física aeróbica en un grupo de adolescentes escolares.

BACKGROUND: The regular practice of physical activity contributes to weight control and improves maximal oxygen uptake (VO2max), socialization and quality of life. AIM: To determine the effect of moderate-to-vigorous physical activity on body composition and VO2max in a group of overweight school-age males. MATERIAL AND METHODS: We studied fifty-five overweight males aged 15.6 ± 0.7 years. Participants were divided in two groups (experimental and control groups). The intervention in the experimental group was the practice of small-sided games during 60 minutes, two days per week and during 11 weeks. At baseline and the end of the intervention, body composition was measured using bioimpedance and VO2max was calculated using the Course Navette test. RESULTS: A 7% reduction in the percentage of body fat and a 9% increase in VO2max were observed in the experimental group (p < 0.01). No changes were recorded in the control group. CONCLUSIONS: Eleven weeks of small-sided exercises performed twice per week increased VO2max and reduced fat mass in overweight adolescents.

[Association of grip strength with gender age and handedness in 116 older people]. / Fuerza prensil de mano y su asociación con la edad, género y dominancia de extremidad superior en adultos mayores autovalentes insertos en la comunidad: Un estudio exploratorio.

BACKGROUND: Hand grip strength could be influenced by gender, age and handedness. AIM: To describe differences in grip strength for age, gender and upper extremity handedness in non-disabled community-dwelling older adults. MATERIAL AND METHODS: We studied 47 males aged 72.3 ± 5.6 years and 69 females 72.4 ± 6.0 years who were divided in two age groups (65-70 and ≥ 71 years old). Grip strength was determined by a standardized protocol using a hand dynamometer. RESULTS: There was an inverse correlation between grip strength and age in both hands only among men (p ≤ 0.05). When analyzing both genders, there was a significant inverse correlation between grip strength and age only in the dominant hand (p ≤ 0.05). Strength was higher in the dominant hand in both genders (p ≤ 0.05). It was also higher in men, compared to women in the two age groups studied (p ≤ 0.05). CONCLUSIONS: Grip strength is higher in men than women, it decreases with age and is higher in the dominant hand.

Exploring lower limb muscle activity and performance variations during instrumented Sit-to-Stand-to-Sit in sedentary individuals: Influence of limb dominance and testing modalities.

PURPOSE: to explore lower limb muscle activity concerning limb dominance, as well as variations in force and power during the standing up and sitting down phases of the instrumented sit-to-stand-to-sit test in sedentary individuals, across isokinetic and isotonic modalities. METHODS: 33 sedentary individuals underwent testing using a functional electromechanical dynamometer in both isokinetic and isotonic modes, accompanied by surface electromyography. RESULTS: In the isokinetic mode, the non-dominant gastrocnemius medialis and vastus medialis exhibited significantly (p < 0.05) higher muscle activity values during the standing up and sitting down phase compared to dominant counterparts. In the isotonic mode standing up phase, significant differences in muscle activity were noted for non-dominant gastrocnemius medialis, vastus medialis, and biceps femoris compared to their dominant counterparts. The sitting down phase in isotonic mode showed higher muscle activity for non-dominant vastus medialis compared to dominant vastus medialis. Regard to performance outcomes, significantly lower (p < 0.0001) values were observed for standing up (12.7 ± 5.1 N/kg) compared to sitting down (15.9 ± 6.1 N/kg) peak force, as well as for standing up (18.7 ± 7.8 W/kg) compared to sitting down (25.9 ± 9.7 W/kg) peak power in isokinetic mode. In isotonic mode, lower values were found for sitting down (6.5 (6.3-7.1) N/kg) compared to standing up (7.8 (7.3-8.9) N/kg) peak force and for sitting down (18.5 (13.2-21.7) W/kg) compared to standing up (33.7 (22.8-41.6) W/kg) peak power. CONCLUSIONS: Limb dominance influences lower-limb muscle activity during the instrumented sit-to-stand-to-sit test, and the choice of testing mode (isokinetic or isotonic) affects muscle engagement and performance outcomes.

Effects of different lower limb strengthening protocols on muscle activity, strength and power in sedentary and physically inactive subjects: a systematic review.

Introduction: 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.

Introducción: 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.

Influence of trunk rotator strength on rotational medicine ball throwing performance.

BACKGROUND: The strength of the trunk musculature plays an essential role in performance. The aims of this study were to analyze the relationship between the strength of the trunk rotation muscles with rotational medicine ball throwing velocity and distance, to study differences between sex in rotational medicine ball throwing and to compare the asymmetries of trunk rotational strength and rotational medicine ball throwing. METHODS: Thirty physically active college students participated on the study. Horizontal and low cable woodchop exercises were assessed with a functional electromechanical dynamometer and throwing was measured with a radar and a measuring tape. A Pearson's correlation coefficient was calculated for the relation between trunk rotational strength and rotational medicine ball throwing. Independent samples t-test was performed to determine the differences between sex in rotational medicine ball throwing and a paired samples t-test was performed to study the asymmetries. RESULTS: Large and very large correlations were obtained between trunk rotational strength and rotational medicine ball throwing (r=0.68-0.79). Significant differences and a large effect size were found between males and females for all throwing velocity and throwing distance variables (P<0.05; ES>0.90) and asymmetries in performance of mean velocity throwing (P=0.003; ES=-0.60) and peak velocity throwing (P=0.025; ES=-0.43). No significant differences were found between dominant and non-dominant side in any of the trunk rotator strength assessment conditions (P>0.05). CONCLUSIONS: There is a large or very large correlation between the STRM and the RMBT in all its modalities. Differences in strength were found between sexes, with no significant differences between dominant and non-dominant sides.

Relationship between natural muscle oscillation frequency and lower limb muscle performance during instrumented sit-to-stand and stand-to-sit movements on a novel device in sedentary subjects.

BACKGROUND: Despite the significance of muscle oscillation frequency, previous research has not established a correlation with muscle performance due to the challenges of applying resistance without altering natural motion during functional tests. RESEARCH QUESTION: What is the correlation between muscle oscillation frequency and lower limb muscle strength, power, and work during an instrumented sit-to-stand and stand-to- sit (iSTS-TS) task among sedentary subjects? METHODS: In a cross-sectional study, the oscillation frequency of the gastrocnemius medialis (GM), biceps femoralis (BF), and vastus medialis (VM) muscles in both the dominant (D) and non-dominant (ND) legs was assessed with a handheld myotonometer in 34 sedentary individuals before performing the iSTS-TS task. RESULTS: In the isokinetic mode, no significant correlations were found. In the isotonic mode, the BF muscle oscillation frequency in the D and ND legs exhibited significant positive correlations with peak force, peak power, and work during sitting down, as well as peak power and work during standing up. Positive correlations were observed in both legs between the GM oscillation frequency and sitting down peak force and work. Additionally, significant positive correlation was found with standing up work in the D leg. Muscle oscillation frequency of the VM exhibited a positive correlation with sitting down peak force in the ND leg. SIGNIFICANCE: Due to a greater number of correlations found, it is advisable to use the isotonic mode when assessing muscle oscillation frequency in relation to muscle performance during functional iSTS-TS tasks in sedentary subjects.