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Objective: This study aimed to determine the association between changes in lactate production and levels of physical activity in a group of healthy young adults in response to two squat training protocols., Material and Methods: Twenty-nine students majoring in Sports Science willingly participated in this study. Participants visited the lab four times within a two-week period, ensuring at least 48 h between visits. In each session, they completed three sets of 12 repetitions at 75% 1RM and three sets of 30 repetitions at 50% of maximum strength, with the order of protocols being randomized., Results: In the regression analysis, there was a significant positive association between lactate delta changes immediately post-squat at 50% of maximum strength at session 2 with the variable "sex: women" (β: 3.02, 95% CI [-0.18-0.30], p  = 0.047) and BMI (kg/m 2 ). Age exhibited a positive association (β: 0.19, 95% CI [0.02-0.36], p  = 0.032) with lactate delta changes immediately post-squat at 75% of maximum strength at session 2. There was also a significant inverse association between lactate delta changes at 10 min post-squat test exercise at 75% of maximum strength at session 1 and 2, and vigorous physical activity (-0.01, 95% CI [-0.02-0.00], p  = 0.046)., Conclusion: In summary, this study provides valuable insights into the association between lactate production and physical activity levels in young, healthy adults undergoing different squat training protocols. These findings suggest that intense physical activity may be associated with lower lactate production, indicating greater metabolic efficiency. In addition, sex differences in metabolic responses were observed, emphasizing the importance of personalized approaches in program design., Competing Interests: The authors declare there are no competing interests., (©2025 del-Cuerpo et al.)

Background: Systematizing reliable protocols and procedures for strength assessment in handball has allowed for a more thorough kinetic analysis and increased precision in detecting training-induced changes in muscular strength. The evaluation of upper limb strength with a bilateral standing press (BSP) exercise in handball players approximates blocking actions in the defensive phase, pushing and fixation., Aim: The aim of this study was to analyze the relative and absolute reliability of intra-session comparisons in an isometric peak muscle strength protocol in a bilateral standing press (BSP) exercise among female handball players., Methods: Sixteen young female handball players at an international level, aged between 22 ± 4 years, with no prior experience in using functional electromechanical dynamometers (FEMD) participated in this study. The participants initiated the assessment of maximum isometric force in a bipedal stance with a forward projection of the dominant foot between 20 and 30 cm. The knees were kept semi-flexed, and the hip extension of the non-dominant limb ranged from 15 to 20°. Bilateral anterior push of the upper limb was performed with shoulder abduction and elbow flexion at 90°, maintaining a pronated hand position. Participants were instructed to exert three sets of maximal force for 5 s in BSP exercise. Relative reliability was assessed using the model intraclass correlation (ICC) and absolute reliability was assessed using the coefficient of variation (CV) and standard error of measurement (SEM). For this study, the parameters of maximum and mean muscle strength were considered., Results: The results demonstrated high relative reliability (ICC 0.93-0.97) and absolute reliability (SEM 0.19-2.79) y (CV 4.78-9.03) for both mean force and peak force, with no significant differences between the sets ( p > 0.05), indicating a negligible effect size (0.01-0.12)., Conclusion: The mean and peak isometric muscle strength for the BSP exercise controlled with FEMD in female handball players exhibits high relative and absolute reliability between series., Competing Interests: The authors declare that they have no competing interests., (© 2024 Cifuentes-Zapata et al.)

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.

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., (Copyright © 2023 National Strength and Conditioning Association.)

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., (© 2023. The Author(s).)

Objective: To evaluate the effects of exergames added to a conventional physical therapy (CPT) program on functional fitness and dynamometric muscle performance for the sit-to-stand (STS) maneuver in older adults and to compare their results concerning a CPT-only intervention. Materials and Methods: Fifty independent older adults were randomly assigned to CPT and exergames (CPT+ExG group; n  = 25; age = 71.8 ± 6.8 years) or CPT alone (CPT group; n  = 25; age = 71.3 ± 7.4 years). CPT was performed twice a week (60 min/session) for 8 weeks. The CPT+ExG group added exergames for 30 minutes in each session. The Senior Fitness Test was applied, considering the 30-second chair stand test as the primary outcome. Additionally, dynamometric muscle performance during the STS maneuver was assessed. Results: The CPT+ExG group improved the 30-second chair stand (lower body strength), back scratch (upper body flexibility), and 8-foot up-and-go (agility/dynamic balance) tests (all P  < 0.05). Both groups improved the kinetic dynamometric variables peak force, peak power, and total work (all P  < 0.05). Also, both groups improved the 30-second arm curl test (upper body strength) ( P  < 0.05), although the increase was higher in the CPT+ExG group compared with the CPT group (time × group; P  < 0.05). Conclusion: Adding exergames to a CPT program only significantly increases upper limb strength compared with CPT alone. The findings of this study have implications for the design of future exergame interventions focused on improving STS maneuver performance in older adults.

The use of strength training is important for athletes in combat sports such as judo and jiu-jitsu. Specificity is key when prescribing strength training programs for athletes, considering maximal strength, muscular power and strength-endurance. Grappling combat sports require grip control, which is necessary to execute throwing techniques and groundwork. The aim of this study was to verify the bilateral strength deficit in general and in grappling combat sport-specific action in the control group and grapplers. A sample of 73 subjects, divided into 2 groups, was used: the Student Group (15 females and 16 males) and the Grappler Group (29 males and 13 females). The male and female participants attended four laboratory sessions over a 48-hour interval, the first two to familiarize themselves with the Electromechanical Functional Dynamometer (EMFD), and the last two to collect maximal isometric strength data, using a standard grip and a judo/jiujitsu specific grip. Significant differences in mean and peak forces ( p  < 0.001) were found, with high performance combat sport athletes having greater maximal isometric strength compared to students both bilaterally and unilaterally ( p  < 0.001). All comparisons also indicated higher values for males compared to females ( p  < 0.001). The results suggest that specific training in combat sports as well as sex differences play a significant role in maximal isometric strength performance. The type of grip used affects the application of force in the upper limb isometric strength tests, finding a main effect of grip type ( p  < 0.001), with the standard grip obtaining higher levels. However, the dominance between hands remains constant. More research is needed on specific judogi/jiu-jitsu-gi grips and their impact on maximal isometric strength with the EMFD., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Escobar-Molina, Cuevas-Laguna, Chirosa-Ríos, Merino-Fernández, Chirosa-Ríos and Franchini.)

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.

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 architecture., Competing Interests: The authors declare that they have no competing interests., (© 2023 Lizama-Pérez et al.)

Neurocognitive function, especially executive functioning, is positively associated with better fitness or higher levels of physical activity (PA). Previous research suggests that combined endurance and resistance (AER+R) training leads to greater improvements than training in either modality separately. Dynamic team sports with cognitive dimensions, such as basketball (BAS), may be an excellent context for improving cognition. This study compared the effects of following a four-month PA training program in BAS versus AER+R on executive functions along with a control group with low PA. Fifty participants completed the training period and were randomly distributed into three groups: BAS (16 participants), AER+R (18), and control (16). Participants in the BAS group showed improved inhibition and working memory and those in the AER+R group showed improved inhibition and cognitive flexibility, while inhibition deteriorated in the control group. There were significant differences between groups only in inhibition. It appears that following a four-month PA training program is enough to enhance executive functioning, and improvements in inhibition are more evident when the program includes an open sport such as BAS., (© 2023. The Author(s).)

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.

Variable resistance (VR) is a methodology that has shown good results in developing muscular strength and power. However, no updated information relates to the use of VR as an activation to trigger post-activation performance enhancement (PAPE). The primary objective of this systematic review and meta-analysis was to review and qualitatively describe studies published between 2012 and 2022 that used VR to generate PAPE in muscle power-dominant sports. The secondary objective was to calculate the effect size of the different power outcomes reported in the selected studies. The search was designed following the PRISMA ® guidelines for systematic reviews and meta-analyses and performed in the Web of Science (WOS), Scopus, SPORTDiscus, PubMed, and MEDLINE between 2012 and 2022. The methodological quality and risk of bias were evaluated with the Cochrane Collaboration tool. The main variables were the throwing speed, time in sprint tests, and jump height. The analysis was conducted with a pooled standardized mean difference (SMD) through a Hedges' g test (95% CI). Twenty-two studies were included in the systematic review and ten in the meta-analysis, revealing a trivial effect for throwing speed (SMD = 0.06; CI = 95%: -0.23-0.35; p = 0.69), a small effect for the time in sprint tests (SMD = -0.37; CI = 95%: -0.72--0.02; p = 0.04), and a moderate effect for jump height (SMD = 0.55; CI = 95%: 0.29-0.81; p ˂ 0.0001). All forms of VR used for neuromuscular activation effectively triggered PAPE. Specifically, the results showed that activation with VR generates performance increases in time, in sprint tests and jump height, and a trivial effect in throwing tests (speed and distance).

Background: Soccer is the most widely practiced sport in the world, demanding high-speed activities such as jumps, sprints and changes of direction. Therefore, having optimal levels of muscle strength improves performance and reduces the injury rate., Objectives: The objectives of our study were (i) to determine the dynamometric profile of hip muscle strength in young soccer players by position, evaluated at different isokinetic speeds, (ii) to describe the conventional and functional unilateral muscle strength ratios, (iii) to analyze the bilateral balance., Methods: Thirty-seven male soccer players (age 17.02 ± 0.92 years) participated in the study. Strength assessment was performed with a functional electromechanical dynamometer, and concentric and eccentric strength of abductors, adductors, extensors and hip flexors were measured bilaterally at 0.5 m/s and 1 m/s., Results: For eccentric right hip abduction at 0.5 m/s, defenders are significantly stronger than midfielders ( p = 0.013) and stronger than forwards ( p = 0.140). For eccentric right hip adduction at 0.5 m/s, defenders are significantly stronger than midfielders ( p = 0.005) and stronger than forwards ( p = 0.253), as for eccentric right hip adduction at 1 m/s, defenders are significantly stronger than midfielders ( p = 0.014) and stronger than forwards ( p = 0.084). There is a significant effect for the conventional strength ratio of left abduction/adduction at 1 m/s. The conventional strength ratio of forwards is significantly higher than that of defenders ( p = 0.045) and higher than that of midfielders ( p = 0.152)., Conclusions: Concentric and eccentric hip strength values differ according to playing position.

Background: the main objective of this study was to evaluate the test-retest reliability of two different functional electromechanical dynamometry (FEMD)-controlled squat training protocols., Methods: twenty-eight healthy young adults volunteered to participate in this study. They attended the laboratory on four different days and performed four sessions: two of three sets of 12 repetitions at 75% 1RM and two of three sets of 30 repetitions at 50% 1RM. The range of movement (ROM), mean dynamic strength (MDS), peak dynamic strength (PDS), mean velocity (MV), peak velocity (PV), mean potency (MP), peak potency (PP), work (W), and impulse (I) were recorded. 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 very high for ROM (CV: 3.72%, ICC: 0.95), MDS (CV: 1.09%, ICC: 1.00), PDS (CV: 1.97%, ICC: 1.00), and W (CV: 4.69%, ICC: 1.00) conditions at 50% 1RM and for ROM (CV: 3.90%, ICC: 0.95), MDS (CV: 0.52, ICC: 1.00), PDS (CV: 1.49%, ICC: 0.98), and W (CV: 4.14%, ICC: 1.00) conditions at 75% 1RM and high for the rest of variables at 50 and 75% 1RM., Conclusions: this study demonstrates that FEMD is a reliable instrument to measure ROM, MDS, PDS, MV, PV, PV, MP, MP, W, and I during both squat protocols (50 and 75% 1RM) in healthy young adults.

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.

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., (Copyright © 2020 National Strength and Conditioning Association.)

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., Competing Interests: The authors declare that there is no conflict of interest., (Copyright © Biology of Sport 2021.)

Background: The objective of this systematic review and meta-analysis was to examine the reliability of isokinetic measurements of hip strength in flexion and extension in healthy subjects and athletes., Methods: The databases used were Web of Science, SCOPUS, Medline and PubMed. R was used for all statistical analyses., Results: Hip flexion shows moderate reliability in the supine position (ICC = 0.72; 95% CI: 0.46-0.99) and good reliability in the standing position (ICC = 0.79; 95% CI: 0.54-1.04). Hip extension shows excellent reliability in the supine position (ICC = 0.90; 95% CI: 0.85-0.96) and moderate reliability in the standing position (ICC = 0.72; 95% CI: 0.48-0.96). Flexion of 120°/s and 180°/s showed excellent reliability (ICC = 0.93; 95% CI: 0.85-1.00), (ICC = 0.96; 95% CI: 0.92-1.01). The 60°/s and 120°/s extension showed good reliability (ICC = 0.90; 95% CI: 0.82-0.98), (ICC = 0.87; 95% CI: 0.75-0.99). The 180°/s extension presented excellent reliability (ICC = 0.93; 95% CI: 0.82-1.03)., Conclusions: The standing position shows good reliability for hip flexion and the supine position shows excellent reliability for hip extension, both movements have excellent reliability at velocities between 120°/s to 180°/s.

Background: Sleep is an important modulator of neuroendocrine function and glucose metabolism. Poor sleep quality is related to metabolic and endocrine alterations, including decreased glucose tolerance, decreased insulin sensitivity, and increased hunger and appetite., Objective: The aim of the present study was to determine the association between sleep quality with metabolic syndrome (MetS) markers, fitness and body fat of women with severe/morbid obesity., Methods: This cross-sectional study included 26 women with severe/morbid obesity. Fasting plasma glucose (FPG), high-density lipids (HDL-c), triglycerides (TGs), and the metabolic outcomes total cholesterol (Tc) and low-density lipids (LDL-c), systolic (SBP) and diastolic blood pressure (DBP), body composition and fitness were measured., Results: Poor sleep quality showed a positive association with body fat (%) ≥ 48.2 (OR; 8.39, 95% CI; 1.13-62.14, p = 0.037), morbid obesity (OR; 8.44, 95% CI; 1.15-66.0, p = 0.036), glucose ≥ 100 mg/dL (OR; 8.44, 95% CI; 1.15-66.0, p = 0.036) and relative handgrip strength ≤ 0.66 (OR; 12.2, 95% CI; 1.79-83.09, p = 0.011)., Conclusion: sleep quality is associated with health markers in women with severe/morbid obesity.

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., Competing Interests: The authors declare that they have no competing interests., (© 2021 Sánchez-Sánchez et al.)

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.

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 (SmO 2 ) 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 SmO 2 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.

Purpose: To compare the effects of 2 upper-body strength-training programs differing in set configuration on bench press 1-repetition maximum (BP1RM), bench press throw peak velocity against 30 kg (BPT30), and handball throwing velocity., Methods: Thirty-five men were randomly assigned to a traditional group (TRG; n = 12), rest redistribution group (RRG; n = 13), or control group (n = 10). The training program was conducted with the bench press exercise and lasted 6 weeks (2 sessions per week): TRG-6 sets × 5 repetitions with 3 minutes of interset rest; RRG-1 set × 30 repetitions with 31 seconds of interrepetition rest. The total rest period (15 min) and load intensity (75% 1RM) were the same for both experimental groups. Subjects performed all repetitions at maximal intended velocity, and the load was adjusted on a daily basis from velocity recordings., Results: A significant time × group interaction was observed for both BP1RM and BPT30 (P < .01) due to the higher values observed at posttest compared with pretest for TRG (effect size [ES] = 0.77) and RRG (ES = 0.56-0.59) but not for the control group (ES ≤ 0.08). The changes in BP1RM and BPT30 did not differ between TRG and RRG (ES = 0.04 and 0.05, respectively). No significant differences in handball throwing velocity were observed between the pretest and posttest (ES = 0.16, 0.22, and 0.02 for TRG, RRG, and control group, respectively)., Conclusions: Resistance-training programs based on not-to-failure traditional and rest redistribution set configurations induce similar changes in BP1RM, BPT30, and handball throwing velocity.

Background: This study aimed to compare the effect of two upper-body resistance training programs (strength-oriented vs. ballistic) on bench press (BP) performance and handball throwing velocity (HTV)., Methods: Thirty resistance-trained males were randomly assigned to a strength-oriented training group (STG) or a ballistic training group (BTG). The study consisted of 11 sessions: 2 pre-tests (week 1), 8 training sessions (weeks 2-5), and 1 post-test (week 6). The STG performed the BP at the 70-90% of the one-repetition maximum (1RM), and the BTG the BP throw at the 40% of 1RM. BP performance (BP 1RM and maximum velocity achieved against 20 kg [BP20]) and HTV were assessed before and after training., Results: The STG enhanced BP 1RM (effect size [ES]=0.24) but not BP20 (ES=0.21) or HTV (ES=0.10). The BTG enhanced BP20 (ES=0.63) but not BP1RM (ES=0.27) or HTV (ES=0.02). HTV was not significantly correlated with the BP 1RM (r≤0.181) or BP20 (r≤0.220)., Conclusions: These results indicate that a short-term RT program based exclusively on the BP exercise performed against either heavy (strength-oriented) or light loads (ballistic) is not effective to increase HTV in resistance-trained men with little handball experience.

Background: The evaluation of the force in internal rotation (IR) and external rotation (ER) of the shoulder is commonly used to diagnose possible pathologies or disorders in the glenohumeral joint and to assess patient's status and progression over time. Currently, there is new technology of multiple joint isokinetic dynamometry that allows to evaluate the strength in the human being. The main purpose of this study was to determine the absolute and relative reliability of concentric and eccentric internal and external shoulder rotators with a functional electromechanical dynamometer (FEMD)., Methods: Thirty-two male individuals (21.46 ±  2.1 years) were examined of concentric and eccentric strength of shoulder internal and external rotation with a FEMD at velocities of 0.3 m s -1 and 0.6 m s -1 . Relative reliability was determined by intraclass correlation coefficients (ICC). Absolute reliability was quantified by standard error of measurement (SEM) and coefficient of variation (CV). Systematic differences across velocities testing circumstances, were analyzed with dependent t tests or repeated-measures analysis of variance in case of 2 or more than 2 conditions, respectively., Results: Reliability was high to excellent for IR and ER on concentric and eccentric strength measurements, regardless of velocity used (ICC: 0.81-0.98, CV: 5.12-8.27% SEM: 4.06-15.04N). Concentric outcomes were more reliable than eccentric due to the possible familiarization of the population with the different stimuli., Conclusion: All procedures examined showed high to excellent reliability for clinical use. However, a velocity of 0.60 m s -1 should be recommended for asymptomatic male patients because it demands less time for evaluation and patients find it more comfortable., Competing Interests: The authors declare there are no competing interests., (©2020 Martinez-Garcia et al.)

This study aimed to compare the within-session reliability and magnitude of velocity variables recorded against a range of submaximal loads during the bench press (BP) exercise performed in a Smith machine using different grip widths. Sixteen physically active men (BP one-repetition maximum [1RM] relative to body mass = 1.01 ± 0.19 kg·kg -1 ) were randomly tested on 4 sessions using a close grip width (100% of biacromial width), medium grip width (150% of biacromial width), wide grip width (200% of biacromial width), and self-selected grip width (176 ± 17% of biacromial width). Mean velocity (MV), maximum velocity (Vmax), and vertical displacement were recorded with a linear velocity transducer against the 35%1RM, 55%1RM, and 75%1RM. The main findings revealed that (I) the self-selected was the only grip width with an acceptable reliability for all loads and velocity variables (CV ≤ 7.56%; ICC ≥ 0.82), (II) the medium grip width provided the highest reliability for MV (CV ratio ≥ 1.20), while a comparable reliability was observed for Vmax using the close, medium and self-selected grip widths (CV ratio ≤ 1.08), (III) the Vmax showed the highest reliability for all grip widths (CV ratio = 1.68), and (IV) the MV and vertical displacement of the barbell were generally higher for narrow grip widths (close and medium) compared to the wide and self-selected grip widths, while no significant differences between the grip widths were observed for Vmax ( p  > .05). Taken together, we recommend the assessment of Vmax using a self-selected grip width during the routine testing of BP performance against submaximal loads.

The purpose of this study was to analyze the on-court demands of handball players during the European Handball Federation Champions League Final Four (VELUX EHF FINAL4) 2019 to define time-motion characteristics (played time; covered distances) both in offense and defense. Furthermore; we aimed to define position-specific demands and differences among them. Forty players from three teams were analyzed during the tournament using a local positioning system (LPS) for the first time in top handball. Players covered similar distances both in offense (1388.28 ± 2627.08 m), and in defense (1305.47 ± 5059.64 m) and remained on court for a similar average time (15.69 ± 8.02 min and 15.40 ± 8.94 min respectively). When locomotion activities were normalized according to the time they spent on court; significant differences were found for defense compared to offense in walking (+20%; p < 0.000; Cohen's effect size (ES) = 1.01) and jogging (-29.6%; p = 0.000; ES = 0.90), as well as a tendency for high-intensity running (+ 25.2%; p = 0.077; ES = 0.31). Per playing position; center and left back (CB = 94.86 ± 10.98 m·min -1 ; LB = 96.55 ± 24.65 m·min -1 ) showed the highest running pace in offense and mid-left; front center defender and outside right for the defense (ML = 90.38 ± 30.16 m·min -1 ; FCD = 87.04 ± 14.94 m·min -1 ; OR = 89.64 ± 34.93 m·min -1 ). In conclusion; profile differences existed among players' position activity; both in offense and defense; which should be taken into account when designing specific physical training programs.

Purpose: To compare the load-velocity (L-V) relationship between bench-press exercises performed using 4 different grip widths, to determine the association between the anthropometric characteristics and L-V profile, and to explore whether a multiple linear-regression model with movement velocity and subjects' anthropometric characteristics as predictor variables could increase the goodness of fit of the individualized L-V relationship., Methods: The individual L-V relationship of 20 men was evaluated by means of an incremental loading test during the bench-press exercise performed on a Smith machine using narrow, medium, wide, and self-selected grip widths. Simple and multiple linear-regression models were performed., Results: The mean velocity associated with each relative load did not differ among the 4 grip widths (P ≥ .130). Only body height and total arm length were correlated with the mean velocity associated with light and medium loads (r ≥ .464). A slightly higher variance of the velocity attained at each relative load was explained when some anthropometric characteristics were used as predictor variables along with the movement velocity (r2 = .969 [.965-.973]) in comparison with the movement velocity alone (r2 = .966 [.955-.968]). However, the amount of variance explained by the individual L-V relationships was always higher than with the multiple linear-regression models (r2 = .995 [.985-1.000])., Conclusions: These results indicate that the individual determination of the L-V relationship using a self-selected grip width could be recommended to monitor relative loads in the Smith machine bench-press exercise.

Aim: To determine the absolute and relative reliability of functional trunk tests, using a functional electromechanical dynamometer to evaluate the isokinetic strength of trunk flexors and to determine the most reliable assessment condition, in order to compare the absolute and relative reliability of mean force and peak force of trunk flexors and to determine which isokinetic condition of evaluation is best related to the maximum isometric., Methods: Test-retest of thirty-seven physically active male student volunteers who performed the different protocols, isometric contraction and the combination of three velocities (V 1 = 015 m s -1 , V 2 = 0.30 m  s -1 , V 3 = 0.45 m s -1 ) and two range of movement (R 1 = 25% cm ; R 2 = 50% cm) protocols., Results: All protocols to evaluate trunk flexors showed an absolute reliability provided a stable repeatability for isometric and dynamic protocols with a coefficient of variation (CV) being below 10% and a high or very high relative reliability (0.69 < intraclass correlation coefficient [ICC] > 0.86). The more reliable strength manifestation (CV = 6.82%) to evaluate the concentric contraction of trunk flexors was mean force, with 0.15 m  s -1 and short range of movement (V 1 R 1 ) condition. The most reliable strength manifestation to evaluate the eccentric contraction of trunk flexors was peak force, with 0.15 m  s -1 and a large range of movement (V 1 R 2; CV = 5.07%), and the most reliable way to evaluate isometric trunk flexors was by peak force (CV = 7.72%). The mean force of eccentric trunk flexor strength with 0.45 m  s -1 and short range of movement (V 3 R 1 ) condition (r = 0.73) was best related to the maximum isometric contraction., Conclusion: Functional electromechanical dynamometry is a reliable evaluation system for assessment of trunk flexor strength., Competing Interests: The authors declare there are no competing interests., (©2019 Rodriguez-Perea et al.)

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.

Background: Older adults with hip osteoarthritis (OA) suffer a progressive loss of muscle quality and strength, affecting their daily activities and quality of life. The purpose of this study is to compare the levels of isometric strength among older adults with and without hip OA and healthy young adults, and to determine the relationship between muscle quality index (MQI) and isometric strength., Methods: Fourteen subjects with hip OA (65.6 ± 3.0 years), 18 healthy older adults (66.6 ± 6.5 years) and 32 young adults (20.7 ± 2.0 years) participated in the study. MQI, isometric muscle strength of the hip, ten time sit-to-stand tests, and body composition were measured., Results: The MQI was lower in subjects with hip OA, with no significant differences between groups ( p  > 0.054). Subjects with OA produced significantly less isometric strength in hip extension ( p  < 0.001), flexion ( p  < 0.001), abduction ( p  < 0.05), adduction ( p  < 0.001), external ( p  < 0.05) and internal rotation ( p  < 0.05). Subjects with OA demonstrated longer time in the execution of the sit-to-stand test ( p  < 0.001) in comparison with healthy older and young adults. High correlations between MQI, sit-to-stand ( r  =  - 0.76, p  < 0.01) and peak force during hip abduction ( r  = 0.78, p  < 0.01) where found in subjects with OA. Moderate correlation between MQI and peak force during hip flexion ( r  = 0.55, p  < 0.05) and external rotation ( r  = 0.61, p  < 0.05) were found in the OA group., Conclusions: Subjects with OA have lower MQI than old and young healthy controls. In subjects with OA, there was a significant relationship between isometric strength of hip muscles and performance on the sit-to-stand test and the MQI., Competing Interests: The authors declare there are no competing interests.

Background: The aim of this study was to examine whether the addition of very light loads for modeling the force-velocity (F-V) relationship during the bench press (BP) exercise can confirm its experimental linearity as well as to increase the reliability and concurrent validity of the F-V relationship parameters (maximum force ( F 0 ), maximum velocity ( V 0 ), F-V slope, and maximum power ( P max ))., Method: The F-V relationship of 19 healthy men were determined using three different methods: (I) 6-loads free method: six loads performed during the traditional free-weight BP exercise (≈ 1-8-29-39-49-59 kg), (II) 4-loads free method: four loads performed during the traditional free-weight BP exercise (≈ 29-39-49-59 kg), and (III) 4-loads Smith method: four loads performed during the ballistic bench press throw exercise in a Smith machine (≈ 29-39-49-59 kg)., Results: The linearity of the F-V relationship was very high and comparable for the three F-V methods ( p = 0.204; median Pearson's correlation coefficient ( r ) = 0.99). The three methods were ranked from the most to the least reliable as follows: 6-loads free (coefficient of variation (CV) range = 3.6-6.7%) > 4-loads Smith (CV range = 4.6-12.4%) > 4-loads free (CV range = 3.8-14.5%). The higher reliability of the 6-loads free method was especially pronounced for F-V slope (CV ratio ≥ 1.85) and V 0 (CV ratio ≥ 1.49) parameters, while the lowest difference in reliability was observed for F 0 (CV ratio ≤ 1.27). The 6-loads free and 4-loads free methods showed a very high concurrent validity respect to the 4-loads Smith method for F 0 and P max ( r ≥ 0.89), a moderate validity for the F-V slope ( r = 0.66-0.82), and a low validity for V 0 ( r ≤ 0.37)., Discussion: The routine testing of the F-V relationship of upper-body muscles through the BP exercise should include trials with very light loading conditions to enhance the reliability of the F-V relationship., Competing Interests: The authors declare that they have no competing interests.

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.

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.

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.