Effectiveness of elastic band training and group-based dance on physical-functional performance in older women with sarcopenia: a pilot study.

BACKGROUND: Sarcopenia is a syndrome associated with aging that causes progressive loss of skeletal muscle mass and muscle function. In this pilot study, we compared the effectiveness of elastic band training regarding group-based dance on fat mass, fat-free mass, handgrip strength (HGS; dominant and non-dominant hand), leg strength, timed up-and-go (TUG) and walking speed in older women with sarcopenia. METHODS: This is a randomized controlled trial, single-blind, repeated measures of parallel groups (elastic band group: EBG, n = 21; group-based dance: GBD, n = 19), and a quantitative methodology. Three 60-minute sessions per week for 12 weeks were dedicated to the interventions with pre- and post-assessments. A two-factor mixed analysis of variance (ANOVA) model with repeated measures was performed to measure the group×time effect. RESULTS: A significant interaction revealed for fat-free mass (F1,16= 18.91; p < 0.001; EBG + 10.9% vs. GBD - 1.97%), HGS dominant hand (F1,16= 7.44; p = 0.014; EBG + 10.9% vs. GBD + 0.59%), HGS non-dominant hand (F1,16= 6.41; p = 0.022; EBG + 10.21% vs. GBD + 3.80%), leg strength (F1,16= 17.98; p < 0.001; EBG + 9.1% vs. GBD + 3.83%), TUG (F1,16= 7.52; p = 0.014; EBG - 14.7% vs. GBD - 1.0%) and walking speed (F1,16 = 6.40; p = 0.019; EBG - 7.6% vs. GBD - 4.35%) in favor of EBG. CONCLUSION: Elastic band training produces significantly greater responses on physical-functional performance regarding group-based dance in older women with sarcopenia. On the other hand, the EBG revealed a significant improvement in fat-free mass and upper and lower limb muscle strength, as well as a significant decrease time in TUG, and walking speed. Elastic band exercise is a safe, easy, affordable, and effective physical activity strategy, according to the findings.

[High intensity interval training in teenagers]. / Efectividad de ejercicio físico intervalado de alta intensidad en las mejoras del fitness cardiovascular, muscular y composición corporal en adolescentes: una revisión.

This review analyzes the effects of high intensity interval training (HIIT) on muscle and cardiovascular fitness and body composition in teenagers. A search was carried out in international databases, finding 145 papers and selecting five for analysis. In all the reviewed manuscripts, peak oxygen uptake improved after HIIT. In the three manuscripts that measured muscle strength, it also increased. We conclude that HIIT improves muscle strength and cardiovascular fitness in school age children. A 12 weeks protocol with three 12-minute sessions per week would be ideal.

[Exercise and oxidative stress in type 2 diabetes mellitus]. / Efecto del ejercicio físico sobre marcadores de estrés oxidativo en pacientes con diabetes mellitus tipo 2.

Sedentarism, overweight and malnutrition generate an increase in the production of reactive oxygen species leading to a state of chronic oxidative stress. In patients with type 2 diabetes mellitus, oxidative stress alters pancreatic insulin secretion and the actions of the hormone on target cells, contributing to the development of micro and macrovascular complications. During physical exertion a state of transient oxidative stress occurs. As a consequence, the organism generates multiple physiological adaptations to these repetitive stimuli. Physical exercise is beneficial for type 2 diabetes mellitus but there is a paucity of information about the effects of physical exercise on biomarkers of oxidative stress in patients with the disease. We herein try to elucidate if the effects of exercise on oxidative stress can help in the prevention and treatment of type 2 diabetes mellitus and which is the most effective modality of physical exercise to reduce oxidative stress markers.

[Association between health anthropometric indexes with physical fitness in physically active elderly women]. / Asociación entre índices antropométricos de salud y condición física en mujeres mayores físicamente activas.

OBJECTIVE: To associate health anthropometric indexes with physical fitness of elderly women (EW) who participate in physical exercise workshops. MATERIALS AND METHODS: 272 Chilean women over 60 years took part in the study. The variables studied were BMI, waist circumference (WC), waist-height index (WHI) and physical fitness (PF). Correlations were made through the Pearson or Spearman coefficient, and bivariate associations using Pearson's Chi-square and the Fisher's exact test, considering p<0.05. RESULTS: 70.8% of the EW were overweight or obese; 68.8% and 96% were at cardiometabolic risk due to their WC and WHI, respectively. Their PF showed equal performance (53.5%) or higher (33.8%) according to their age and gender. Inverse correlations were found between nutritional status and cardiometabolic risk with PF tests (except for agility and dynamic balance [direct]), and direct association with back scratch test. CONCLUSIONS: Excess weight in physically active EW would not affect their physical-functional performance; however, cardiometabolic risk would be inversely associated with motor function.

OBJETIVO: Asociar los índices antropométricos de salud con la condición física de las mujeres mayores (MM) que participan en talleres de ejercicio físico. MATERIAL Y MÉTODOS: Participaron 272 mujeres chilenas mayores de 60 años. Las variables correspondieron al IMC, perímetro de cintura (PC), índice cintura estatura (ICE) y condición física (CF). Se realizaron correlaciones a través del coeficiente de Pearson o Spearman, y asociaciones bivariadas mediante ji cuadrada de Pearson y el test exacto de Fisher, considerando un p<0.05. RESULTADOS: De las MM, 70.8% alcanzó sobrepeso u obesidad; y 68.8% y 96% riesgo cardiometabólico de acuerdo con PC e ICE, respectivamente. Su CF presentó un rendimiento igual (53.5%) o superior (33.8%) según su edad y sexo. Se encontraron correlaciones inversas entre estado nutricional y riesgo cardiometabólico con las pruebas de CF (excepto la agilidad y equilibrio dinámico, en donde la relación fue directa), y asociación directa con juntar manos. CONCLUSIONES: El exceso de peso en MM físicamente activas no afecta su rendimiento físico-funcional; sin embargo, el riesgo cardiometabólico se asocia inversamente con la funcionalidad motriz.

Quadriceps muscle reaction time in obese children.

This study aimed to determine the influence of obesity, according to body mass index (BMI) and fat mass percentage, on quadriceps muscle reaction times. The study utilized a cross-sectional design. The sample size consisted of 42 schoolchildren (54.5% girls) aged 11 to 12 years old. Participant measurements included weight and height, which were used to categorize individuals based on BMI. Additionally, the electrical bioimpedance technique was employed to categorize participants based on their body fat percentage. A sudden destabilization test of the lower limb was performed to assess the reaction time of the rectus femoris, vastus medialis, and vastus lateralis muscles. The results show that overweight/obese children have a longer muscle reaction time for both the rectus femoris (ß = 18.13; p = 0.048) and the vastus lateralis (ß = 14.51; p = 0.042). Likewise, when the children were classified by percentage of body fat the results showed that overfat/obese children have a longer muscle reaction time for both the rectus femoris (ß = 18.13; p = 0.048) and the vastus lateralis (ß = 14.51; p = 0.042). Our results indicate that BMI and fat mass classification negativity alter the muscle reaction time in children. Overweight/obese or overfat/obese children showed longer reaction times in the rectus femoris and vastus lateralis muscles compared to children with normal weight. Based on these findings, it is suggested that in overweight and obese children, efforts not only focus on reducing body weight but that be complemented with training and/or rehabilitation programs that focus on preserving the normal physiological function of the musculoskeletal system.

Effects of active exergames on physical performance in older people: an overview of systematic reviews and meta-analysis.

This overview assessed the available body of published peer-reviewed systematic reviews and meta-analyses related to the effects of active exergames compared with active/passive control on physical performance outcomes in older people. The methodological quality and certainty of evidence were assessed using PRISMA, AMSTAR 2, and GRADE. The protocol was registered in PROSPERO (code: CRD42023391694). The main outcomes indicate that 4,477 records, five systematic reviews, and 10 meta-analyses were included. The AMSTAR-2 reported six meta-analyses with high methodological quality, four moderate quality, two systematic reviews with low quality, and three very-low quality. Meta-analysis was performed on balance using the Berg Balance Scale (BBS) and Timed Up-and-Go (TUG) tests, on cardiorespiratory fitness using the 6-min walk test, and on upper and lower limbs muscle strength using the handgrip strength, knee extension, and 30-s chair stand tests. Significant differences in favor of the active exergames groups concerning active/passive groups were reported in BBS (SMD = 0.85; 95% CI = 0.12-1.58; I2 = 96%; p = 0.02), TUG (SMD = 1.44; 95% CI = 0.71-2.16; I2 = 97%; p < 0.0001), and 30-s chair stand test (SMD = 0.79; 95% CI = 0.33-1.25; I2 = 88%; p = 0.0008). However, no significant differences were reported in favor of the active exergames groups in 6-min walk (SMD = 0.93; 95% CI = -0.64 to 2.50; I2 = 95%; p = 0.24), handgrip strength (SMD = 0.67; 95% CI = -0.04 to 1.38; I2 = 84%; p = 0.06), and knee extension tests (SMD = 0.20; 95% CI = -0.05 to 0.44; I2 = 95%; p = 0.12) compared to active/passive control. However, it was impossible to perform a meta-analysis for the variables of walking speed as a fall risk due to the diversity of instruments and the small number of systematic reviews with meta-analysis. In conclusion, interventions utilizing active exergames have shown significant improvements in the static and dynamic balance and lower limb muscle strength of apparently healthy older people, compared to control groups of active/inactive participants, as measured by BBS, TUG, and 30-s chair stand tests. However, no significant differences were found in the 6-min walk, HGS, and knee extension tests. Systematic review registration: PROSPERO, CRD42023391694.

Effects of combat sports on cognitive function in older people: a systematic review.

INTRODUCTION: This systematic review aimed to analyze the available body of published peer-reviewed studies on the effects of combat sports compared with active/passive control on cognitive function and electrophysiological markers of brain activity in older people. EVIDENCE ACQUISITION: The studies were searched in Scopus, Web of Science, PubMed, MEDLINE, and PsycINFO databases from deadline to June 2023. The PRISMA, TESTEX, RoB, and GRADE scales assessed the evidence's methodological quality and certainty of evidence. The protocol was registered in PROSPERO (code: CRD42022361695). EVIDENCE SYNTHESIS: After reviewing 3768 studies, seven combat sports interventions (score ≥60% in methodological quality) were selected, composed of 381 older people (63% female), with a mean age of 66 years. In the selected studies, interventions based on judo, karate, and taekwondo were carried out, where it was not possible to verify the benefits of combat sports in cognitive function and electrophysiological markers of brain activity regarding active/passive control groups, although the individual results of the analyzed studies indicate that the practice of combat sports favor selective attention, divided attention, executive function, visual perception, and cognitive processing speed in older people. CONCLUSIONS: The available evidence does not allow a definite recommendation regarding combat sports as an effective cognitive function intervention in older people.

Time-motion analysis of taekwondo matches in the Tokyo 2020 Olympic Games.

BACKGROUND: The aim of the present study was to determine the time-motion structure of high-level taekwondo matches during the Tokyo 2020 Olympic Games in relation to sex, match outcome, weight category and match round. METHODS: Overall, 7007 actions were recorded during the analysis of 134 performances (67 rounds of 24 matches: four rounds of 16, eight quarterfinals, eight semifinals and four finals) in male and female flyweight (≤58 kg and ≤49 kg, respectively), and heavyweight categories (≥80 kg and ≥67 kg, respectively). The attack time (AT), number of AT (AN), skipping time (ST) and pause time (PT) were registered. RESULTS: The AT/ST ratio was ~1:1.5. Male athletes performed significantly longer (P<0.001) sum PT than female athletes. Flyweight athletes differed significantly from their heavyweight counterparts by having longer (P<0.001) average and sum AT, greater (P<0.001) AN, higher (P<0.001) AT/ST ratio, shorter (P<0.001) average and sum ST, and lower (P<0.01) (AT+ST)/PT ratio. Rounds 2 and 3 had average PT significantly longer (P<0.01) than round 1. Round 3 had sum PT longer (P<0.001) and (AT+ST)/PT ratio lower than in round 1. CONCLUSIONS: The rule changes and the implementation of the electronic score recording system had a major impact on the time-motion structure of combat by generating a considerably higher AT/ST ratio than in the past. The comparisons indicated that the structure of the combat is modulated by weight category and phase of the combat. In practice, coaches could develop sport-specific high-intensity interval training using the time-motion indexes of the present study as guidelines.

A Systematic Review with Meta-Analysis on the Effects of Plyometric-Jump Training on the Physical Fitness of Combat Sport Athletes.

We aimed to assess the athletic performance changes in combat sport athletes (CoSAs) after plyometric-jump training (PJT), compared to control conditions, through a systematic review with meta-analysis. Following PRISMA guidelines, three electronic databases were searched for includable articles, according to a PICOS approach. Using a random-effects model, Hedges' g effects sizes (ES) were calculated. Heterogeneity was assessed using the I2 statistic, with values of <25%, 25-75%, and >75% representing low, moderate, and high levels of heterogeneity, respectively. Statistical significance was set at p ≤ 0.05. The certainty of evidence was assessed using the GRADE approach. Twelve eligible articles were identified for systematic review, seven of high quality and five of moderate quality, according to the PEDro scale. The studies recruited taekwondo, silat, wrestling, judo, fencing, and karate athletes (292 total participants), including specific-active and active controls. Most participants had a mean age of <18 years and were males (n = 225). Compared to the control, PJT programmes, involving 4-12 weeks and 2-3 sessions per week, induced small to moderate improvements (ES = 0.47 to 1.04) in athletes' maximal strength (e.g., 1RM squat), vertical jump height, change-of-direction speed, and specific performance (e.g., fencing movement velocity), although without meaningful effects on body mass, fat mass, and muscle mass (ES = 0.02 to -0.06). Most (7 of 8) outcomes attained low heterogeneity. The outcome-level GRADE analysis indicated a certainty of evidence from low to moderate. In conclusion, PJT, when compared to control conditions, may improve CoSA athletic performance.

Relation between VT1, VT2, and VO2max with the Special Wrestling Fitness Test in Youth Wrestlers: A Short Report.

This study investigated the relationship between peak oxygen uptake and ventilatory threshold 1 (VT1) and 2 (VT2) with the Special Wrestling Fitness Test variables. Thirteen wrestlers (male: six; female: seven) of Olympic freestyle wrestling were assessed. The Pearson's correlation coefficient (p < 0.05) was used to establish the relationship between variables. A positive correlation was found between VT1 with throws in set B (r = 0.77; p = 0.002; 95%CI = 0.37-0.93), total throws (r = 0.73; p = 0.004; 95%CI = 0.30-0.91), heart rate recovery (r = 0.58; p = 0.036; 95%CI = 0.05-0.86), and test index (r = -0.60; p = 0.031; 95%CI = -0.86-0.07); between VT2 and throws in set B (r = 0.57; p = 0.043; 95%CI = 0.01-0.86); and between peak oxygen uptake with throws in set B (r = 0.77; p = 0.002; 95%CI = 0.39-0.93), throws in set C (r = 0.64; p = 0.02; 95%CI = 0.12-0.89), and total throws (r = 0.72; p = 0.006; 95%CI = 0.28-0.91). In conclusion, the peak oxygen uptake and ventilatory thresholds correlated with specific Special Wrestling Fitness Test variables.

An investigation into the associations between psychological skills, anaerobic fitness, and aerobic fitness in elite Iranian taekwondo athletes.

This study investigated the relationship between psychological skills and fitness levels among elite taekwondo athletes. A total of ten Iranian male elite taekwondo athletes (mean age of 20.6±2 years, BMI 18.78±0.62 kg/m2, and fat percentage of 8.87±1.46%) participated in the study. The Sports Emotional Intelligence Questionnaire, Sports Success Scale, Sport Mental Toughness Questionnaire, and Mindfulness Inventory for Sport were used to assess psychological factors. The Wingate test was used to determine anaerobic power, and the Bruce test to determine aerobic fitness. Descriptive statistics and Spearman rank correlation coefficients were utilised to examine any relationships between subscales. Statistically significant correlations were recorded between the evaluation of feelings (EI scale) and VO2peak (ml/kg/min) (r = -0.70, p = 0.0235) and between social skills (EI scale) and relative peak power (W/kg) (r = 0.84, p = 0.0026). Also, between optimism (EI scale) and VO2peak (ml/kg/min) (r = -0.70, p = 0.0252) and between optimism (EI scale) and HR-MAX (r = -0.75, p = 0.0123); and, finally, between control (mental toughness scale) and relative peak power (W/kg) (r = 0.67, p = 0.0360). These findings demonstrate relationships between psychological factors and the advantages of good anaerobic and aerobic capabilities. Finally, the study also demonstrated that elite taekwondo athletes have high mental performance abilities that are interrelated with anaerobic and aerobic performance.

Association between Physical Activity Habits with Cardiometabolic Variables, Body Composition, and Physical Performance in Chilean Older Women.

This study aimed to associate physical activity habits with cardiometabolic variables (blood pressure, fasting glucose, HDL cholesterol, and triglycerides), body composition (body fat percentage and fat-free mass), and physical performance (handgrip strength (HGS), timed up-and-go (TUG), and walking speed) in Chilean older women. An analytical cross-sectional study analyzed 179 older women with a mean age of 75.4 years distributed into physically inactive (PI) older women (n = 74) and physically active (PA) older women (n = 105). A logistic regression showed that PI older women presented an increased risk of hyperglycemia (OR = 4.70; p = 0.000), high blood pressure (OR = 3.83; p = 0.000), low HDL cholesterol levels (OR = 2.13; p = 0.03), hypertriglyceridemia (OR = 2.54; p = 0.01), excess body fat percentage (OR = 4.33; p = 0.000), low fat-free mass (OR = 2.22; p = 0.02), low HGS in their dominant hand (OR = 3.37; p = 0.001) and non-dominant hand (OR = 3.60; p = 0.0001), and poor performance in TUG (OR = 5.60; p = 0.000) and walking speed (OR = 5.52; p = 0.000). In conclusion, physical inactivity was associated with increased cardiometabolic risk, excess body fat percentage, lower fat-free mass, and poorer physical performance in Chilean older women. At the same time, PA older women showed a lower cardiometabolic risk, better body composition, and better physical performance than PI older women.

Anthropometric Profile and Physical Activity Level as Predictors of Postural Balance in Overweight and Obese Children.

Overweightness and obesity can negatively influence many activities, including postural balance and locomotion, increasing predisposition to injury and risk of falls due to limitations on the biomechanics of daily living. The present study aimed to determine the influence of the anthropometric profile and physical activity level (PAL) on the postural balance of overweight and obese children. The sample included 387 schoolchildren (216 boys and 171 girls). The variables of the anthropometric profile studied were body mass, biped height, BMI, waist circumference, waist-to-hip ratio (WHR), summation of folds, body composition, and somatotype. PAL was measured using the PAQ-C questionnaire. Static and dynamic postural balance were measured through an open-eye (OE) and closed-eye (CE) posturographic test and the SEBTm, respectively. For static balance, the significant models were for mediolateral velocity (R2 = 0.42 in OA; R2 = 0.24 in OC), anteroposterior velocity (R2 = 0.21 in OA; R2 = 0.27 in OC), and mean velocity (R2 = 0.27 in OA; R2 = 0.46 in OC), where the predictors of low performance were younger age, male sex, overweight/obese nutritional status, greater thickness of skin folds, less tendency to mesomorphy, and greater fat mass. On the other hand, for dynamic postural balance, the significant models were observed in the previous direction (R2 = 0.39), posteromedial (R2 = 0.57), and posterolateral (R2 = 0.56), where the variables that predict a low performance were low PAL, overweight/obese nutritional status, and high WHR. Overweight and obese children presented a deficit in static and dynamic postural balance, enhanced by variables such as gender, age, PAL, and anthropometric characteristics related to adiposity.

Impact of adapted taekwondo vs. multicomponent training on health status in independent older women: a randomized controlled trial.

This study, called the TKD and Aging Project, aimed to analyze and compare the effects of an adapted taekwondo program concerning multicomponent training on blood pressure, morphological variables, food consumption frequency, health-related quality of life (HRQoL), physical fitness, handgrip strength, and postural balance in independent older women. A randomized controlled trial study was conducted with parallel groups for 8 weeks (24 sessions of 60 min each), employing a double-blind design and incorporating repeated measures. Twenty-eight older women initially participated in the intervention. Three participants were excluded because they did not participate in the re-assessments. Thus, 14 older women from the adapted taekwondo group (TKD; age: 62.86 ± 2.38 years) and 11 from the multicomponent training group (MCT; age: 63.18 ± 1.94 years) participated in the final analysis. A two-factor mixed analysis of variance (ANOVA) model with repeated measures was performed to measure the time × group effect. The TKD showed significant improvements in the mental health (p = 0.024; ES = 0.91) and general health (p < 0.001; ES = 0.75) dimensions of the HRQoL, as well as in the chair stand (p = 0.001; ES = 1.18), arm curl (p < 0.001; ES = 2.10), 2-min step (p < 0.001; ES = 1.73), and chair sit-and-reach (p = 0.001; ES = 0.91) tests. Additionally, it showed a significant reduction in postural balance for the eyes-closed condition in the center of the pressure area (p = 0.021; ES = 0.89), mean velocity (p = 0.004; ES = 0.79), and mediolateral velocity (p < 0.001; ES = 1.26). However, the MCT showed significant increases in the general health (p = 0.013; ES = 0.95) dimension of the HRQoL and a significant reduction (p = 0.039; ES = 0.28) in the mediolateral velocity of postural balance for the eyes-closed condition. Multiple comparisons showed that the TKD scored significantly higher in the chair stand (p = 0.017; ES = 1.79), arm curl (p = 0.003; ES = 1.77), and 2-min step (p = 0.018; ES = 0.91) tests than the MCT. Compared to multicomponent training, taekwondo improves postural balance and provides better benefits in terms of physical fitness and HRQoL for older women. Therefore, it is possible to recommend it as a safe physical activity strategy, as long as it is well-dosed, since it showed high adherence to intervention in older women.

Factors Associated with Anxiety, Depression, and Stress Levels in High School Students.

This study aims to investigate the relationship between anxiety, depression, and stress levels with physical activity level and academic performance in high school students; secondly, this study aims to relate and compare anxiety, depression, and stress levels with physical activity level and academic performance. This is a quantitative, descriptive, and comparative cross-sectional study, which evaluated 443 high school students (48% female; 15.13 ± 1.59 years) belonging to the Maule region, Chile. The Depression, Anxiety, and Stress Questionnaire (DASS-21) and the International Physical Activity Questionnaire (IPAQ) were applied. Academic performance was consulted on language, mathematics, and overall grade point average. The results indicate that vigorous physical activity (OR = 0.504; p = 0.017) and high academic performance in mathematics (OR = 0.597; p = 0.027) are associated with a reduced risk of depression. In turn, there is a significant inverse correlation between physical activity with anxiety (r = -0.224; p = 0.000), depression (r = -0.224; p = 0.000) and stress (r = -0.108; p = 0.032), while the performance of mathematics is inversely correlated with depression (r = -0.176; p = 0.000). On the other hand, significant differences (p < 0.05) between anxiety, depression, stress levels, and grade point average were found, with females exhibiting higher scores than males. In conclusion, greater vigorous physical activity and scoring above average in mathematics performance are protective factors against depression.

Effects of Strength Training on Physical Fitness of Olympic Combat Sports Athletes: A Systematic Review.

This review aimed to identify the effects of strength training programs on the physical fitness of Olympic combat sports (OCS) athletes. The systematic review included peer-reviewed articles that incorporated interventions that included pre- and post-intervention physical fitness assessment. The search was performed in the SCOPUS, PubMed, and Web of Science databases between April and September 2022. PRISMA and the TESTEX checklist were used to select and assess the methodological quality of the studies. Twenty studies with 504 participants (428 males and 76 females) were included. Significant improvements were found in athletes' maximal dynamic and isometric strength, muscle power, flexibility, and balance. In addition, improvements in favor of the training groups in specific actions of judo, karate, fencing, and boxing were observed. In conclusion, interventions aimed at the development of muscle strength in OCS, specifically in judo, boxing, karate, wrestling, and fencing, proved to be beneficial at a physical fitness level, resulting in significant increases in favor of the training groups with OCS, which could be used by trainers and coaches to improve the physical performance of athletes.

Corrigendum: Warm-up stretching exercises and physical performance of youth soccer players.

[This corrects the article DOI: 10.3389/fphys.2023.1127669.].

Validity and Reliability of Short-Term Heart Rate Variability Parameters in Older People in Response to Physical Exercise.

BACKGROUND: Currently, and to the best of our knowledge, there is no standardized protocol to measure the effect of low- to moderate-intensity physical exercise on autonomic modulation focused in older people. AIM: Validate a test-retest short-term exercise protocol for measuring the autonomic response through HRV in older people. METHODS: A test-retest study design was used. The participants were selected through intentional non-probabilistic sampling. A total of 105 older people (male: 21.9%; female: 78.1%) were recruited from a local community. The assessment protocol evaluated HRV before and immediately after the 2-min step test. It was performed twice on the same day, considering a time of three chronological hours between the two measurements. RESULTS: The posterior distribution of estimated responses in the Bayesian framework suggests moderate to strong evidence favoring a null effect between measurements. In addition, there was moderate to robust agreement between heart rate variability (HRV) indices and assessments, except for low frequency and very low frequency, which showed weak agreement. CONCLUSIONS: Our results provide moderate to strong evidence for using HRV to measure cardiac autonomic response to moderate exercise, suggesting that it is sufficiently reliable to show similar results to those shown in this test-retest protocol.

Effects of different plyometric training frequencies on physical performance in youth male volleyball players: a randomized trial.

This study aimed to analyze the effect of plyometric training (PT) at different frequencies on jump performance, running sprint speed, and service speed in youth male volleyball players. The participants were randomly assigned to one PT session per week (Experimental Group 1, EG1, n = 15), two PT sessions per week (Experimental Group 2, EG2, n = 14), and a control group (CG, n = 13). The total weekly jumping ranged between 98 and 196 jumps (equalized between, EG1 and, EG2). The assessments performed were squat jump (SJ), countermovement jump (CMJ), CMJ-arms, drop jump (DJ), 5-m sprint, 10-m sprint, and service speed. The intragroup comparisons showed that, EG1 significantly (p < 0.001) improved SJ (Δ = 12.74%; d = 1.30), CMJ (Δ = 11.94%; d = 1.71), CMJ-arms (Δ = 12.02%; d = 1.47), DJ (Δ = 10.93%; d = 1.30), 5-m sprint (Δ = -4.61%; d = 0.29), 10-m sprint (Δ = -3.95%; d = 0.40) and service speed (Δ = 8.17%; d = 1.53). Similarly, EG2 significantly (p˂ 0.001) improved SJ (Δ = 11.52%; d = 1.25), CMJ (Δ = 11.29%; d = 1.38), CMJ-arms (Δ = 11.42%; d = 1.26), DJ (Δ = 13.90%; d = 2.17), 5-m sprint (Δ = -3.85%; d = 0.25), 10-m sprint (Δ = -2.73%; d = 0.25) and service speed (Δ = 6.77%; d = 1.44). The CG significantly (p < 0.05) improved SJ (Δ = 2.68; d = 0.28), CMJ-arms (Δ = 2.30; d = 0.35), 5-m sprint (Δ = -1.27; d = 0.10) and service speed (Δ = 1.42; d = 0.30). Intergroup comparisons revealed significantly greater improvements in all variables (p < 0.001) in, EG1 and, EG2 concerning to CG. However, no significant differences were found between, EG1 and, EG2. A moderate weekly PT volume, distributed in one or two sessions per week, seems equally effective.