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This study aims to explore: (1) the validity of post-exercise ultra-short-term heart rate variability (HRV ust ) after two different bouts of repeated sprint ability test (RSA), and (2) the relationship between HRV ust measure and RSA performance. Twenty adolescent male futsal players voluntarily participated in this study (age: 17.65 ± 1.81 years, body height: 170.88 ± 4.98 cm, body weight: 61.78 ± 4.67 kg). The participants performed a standard RSA test (RSA standard ) and an RSA test with a 10% decrement of the best sprint time test (RSA 10%decrement ) on two separate occasions within a week. On both occasions, a 5-min resting electrocardiography was administered pre- and post-RSA exercise protocols. The first 30-s (HRV ust30s ), 60-s (HRV ust60s ), and 60-120-s (HRV ust1-2min ) were extracted and used to compare with the standard of 5-min HRV recording (HRV criterion ). The natural logarithm (ln) of the standard deviation of normal-to-normal intervals (SDNN) and root mean square of successive normal-to-normal interval differences (RMSSD) HRV indices were utilised to establish intraclass correlation coefficient (ICC 2,1 ), coefficient of variation (%CV), and Pearson product-moment correlation ( r ). Results revealed the ICC values of HRV ust lnSDNN (RSA standard  = 0.77-0.88; RSA 10%decrement  = 0.41-0.71) and lnRMSSD (RSA standard  = 0.81-0.86; RSA 10%decrement  = 0.57-0.82). Furthermore, significantly positive correlations between best sprint time and post-exercise HRV ust indices were found in lnSDNN ( r  = 0.47-0.62; p  < 0.05) and lnRMSSD ( r  = 0.45; p  < 0.05). Additionally, a large CV of lnSDNN (RSA standard  = 32%-45%; RSA 10%decrement  = 29%-39%), lnRMSSD (RSA standard  = 50%-66%; RSA 10%decrement  = 48%-52%), and ratio (RSA standard  = 45%-126%; RSA 10%decrement  = 27%-45%) was found after the RSA protocols. In conclusion, the number of bouts of RSA exercise potentially influences the agreement of post-exercise time-domain HRV ust indices to standard HRV measure., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

This study aimed to investigate the effects of shift work on sleep quality, cardiovascular function, and physical activity (PA) levels in Taiwanese police officers. Twenty-one male police officers aged 26.9 ± 4.1 years old located in Taipei voluntarily participated in this study. The participants completed the resting heart rate (HR) and hemodynamic variables (e.g. blood pressure, BP) before and after day-time (DTW) and night-time (NTW) shift work phases (5 working days and 2 resting days for each phase). Additionally, an actigraphy was administered to measure PA and sleep patterns in the last 3 working days. The average total sleep time and sleep efficiency were 278.5 ± 79. 6 min and 72.9 ± 10%, respectively, in the NTW phases, which were significantly lower than that in the DTW phases. A comparison of the PA characteristics between the two phases revealed that a lower proportion of moderate-vigorous PA (1.2 ± 0.8%) and a greater proportion of sedentary behaviour PA (74.8 ± 6.4%) was found in the NTW phases. The results of hemodynamic measures demonstrated that the police officers have significantly elevated systolic BP by 3.3% and diastolic BP by 3.9% after the NTW phases. Furthermore, the NTW phases exhibited a significantly higher percentage change ratio of systolic BP and diastolic BP compared to the DTW phases. Compared with the DTW phases, the NTW phase was significantly more likely to report higher decreasing parasympathetic-related HR variability with a range of -5.9% to -7.8%. In conclusion, night-time shift work resulted in negative physiological changes leading to adverse effects on the health and well-being of Taiwanese police officers.

Purpose: The International Study of Movement Behaviors in the Early Years (SUNRISE) was conducted in Tunisia to assess the proportion of preschoolers who met the World Health Organization guidelines for physical activity, sedentary behavior, and sleep. The study also evaluated the feasibility of the methods for the SUNRISE study., Methods: Five kindergartens were recruited from urban and rural areas in Tunisia. Physical activity and sleep duration were assessed using a waist-worn ActiGraph. Screen time and sleep quality were assessed via an interview-administered parent questionnaire. The NIH Toolbox was used., Results: A total of 112 preschoolers were assessed (50 boys, age = 4.1 [0.58]). Only 18% of children met all recommendations of the World Health Organization guidelines, while 53% met the sedentary screen time (in minutes per day), and 41% met physical activity recommendation (in minutes per day). Eighty-one percent of children met the sleep duration recommendation (in minutes per day). There was good compliance with the ActiGraph protocol., Conclusions: This pilot study provided important insights into the feasibility of the study and the movement behaviors of Tunisian preschool children. The results suggest there is a need to promote healthy levels of physical activity and sedentary screen time in children, which should be a priority in public health initiatives, including preschool curricula, in Tunisia.

This study examined the effect of a 10-week programme of strength training with elastic band (STEB) on fitness components in young female handball players. Twenty-six young female handball players (aged 15.8 ± 0.2 years) from the same club participated in this study. They were randomly assigned between experimental (EG; n = 13) and control (CG; n = 13) groups. The EG performed the STEB, replacing some handball-specific drills in the regular handball training. The CG followed the regular handball training (i.e., mainly technical-tactical drills, small sided and simulated games, and injury prevention drills). Two-way analyses of variance were used to assess: handgrip; back extensor strength; medicine ball throw; 30 m sprint times; Modified Illinois change-of-direction (Illinois-MT); four jump tests: squat jump (SJ), countermovement jump (CMJ), countermovement jump with arm swing (CMJA) and five-jump test (5JT); static (Stork test) and dynamic balance (Y Balance Test); and repeated sprint T-test (RSTT). Results revealed significant gains in handgrip - right (p < 0.001, d = 1.75: large), handgrip - left (p < 0.001, d = 2.52: large), back extensor (p < 0.001, d = 2.01: large), and medicine ball throw (p = 0.002, d = 0.95: large) with EG compared to the CG. The EG also demonstrated greater improvement in sprint performance over 20 m (Δ = 10.6%, p = 0.001, d = 1.07: large) and 30 m (Δ = 7.2%, p < 0.0001, d = 1.56: large) compared to the CG. The EG showed better Illinois-MT (Δ = 5.6%, p = 0.034, d = 0.62: medium) compared to the CG. Further, EG posted significant improvements in the SJ (Δ = 17.3%, p = 0.048, d = 0.58: medium), CMJ (Δ = 17.7%, p = 0.017 d = 0.71: medium), and CMJA (Δ = 16.3%, p = 0.019, d = 0.69: medium) compared to the CG. Similarly, the EG exhibited significant improvement in RSTT best time [p = 0.025, d = 0.66 (medium)], RSTT mean time [p = 0.019, d = 0.69 (medium)] and RSTT total time [p = 0.019, d = 0.69 (medium)] compared to the CG. In conclusion, the 10-week STEB improved the physical abilities in young female handball players., Competing Interests: The authors declare that they have no competing interests., (Copyright © Biology of Sport 2022.)

Purpose: To investigate differences in athletes' knowledge, beliefs, and training practices during COVID-19 lockdowns with reference to sport classification and sex. This work extends an initial descriptive evaluation focusing on athlete classification., Methods: Athletes (12,526; 66% male; 142 countries) completed an online survey (May-July 2020) assessing knowledge, beliefs, and practices toward training. Sports were classified as team sports (45%), endurance (20%), power/technical (10%), combat (9%), aquatic (6%), recreational (4%), racquet (3%), precision (2%), parasports (1%), and others (1%). Further analysis by sex was performed., Results: During lockdown, athletes practiced body-weight-based exercises routinely (67% females and 64% males), ranging from 50% (precision) to 78% (parasports). More sport-specific technical skills were performed in combat, parasports, and precision (∼50%) than other sports (∼35%). Most athletes (range: 50% [parasports] to 75% [endurance]) performed cardiorespiratory training (trivial sex differences). Compared to prelockdown, perceived training intensity was reduced by 29% to 41%, depending on sport (largest decline: ∼38% in team sports, unaffected by sex). Some athletes (range: 7%-49%) maintained their training intensity for strength, endurance, speed, plyometric, change-of-direction, and technical training. Athletes who previously trained ≥5 sessions per week reduced their volume (range: 18%-28%) during lockdown. The proportion of athletes (81%) training ≥60 min/session reduced by 31% to 43% during lockdown. Males and females had comparable moderate levels of training knowledge (56% vs 58%) and beliefs/attitudes (54% vs 56%)., Conclusions: Changes in athletes' training practices were sport-specific, with few or no sex differences. Team-based sports were generally more susceptible to changes than individual sports. Policy makers should provide athletes with specific training arrangements and educational resources to facilitate remote and/or home-based training during lockdown-type events.

Verbal encouragement (VE) can be used by physical education (PE) practitioners for boosting motivation during exercise engagement. The purpose of this study was to investigate the effects of VE on psychophysiological aspects and physical performance in a PE context. Twenty secondary school male students (age: 17.68 ± 0.51 yrs; height: 175.7 ± 6.2 cm; body mass: 67.3 ± 5.1 kg, %fat: 11.9 ± 3.1%; PE experience: 10.9 ± 1.0 yrs) completed, in a randomized order, two test sessions that comprised a soccer dribbling circuit exercise (the Hoff circuit) either with VE (CVE) or without VE (CNVE), with one-week apart between the tests. Heart rate (HR) responses were recorded throughout the circuit exercise sessions. Additionally, the profile of mood-state (POMS) was assessed pre and post the circuit exercises. Furthermore, rating of perceived exertion (RPE), traveled distance, and physical activity enjoyment (PACES) were assessed after the testing sessions. Furthermore, the CVE trial resulted in higher covered distance, %HRmax, RPE, PACES score, (Cohen’s coefficient d = 1.08, d = 1.86, d = 1.37, respectively; all, p < 0.01). The CNVE trial also showed lower vigor and higher total mood disturbance (TMD) (d = 0.67, d = 0.87, respectively, p < 0.05) and was associated with higher tension and fatigue, compared to the CVE trial (d = 0.77, d = 1.23, respectively, p < 0.01). The findings suggest that PE teachers may use verbal cues during soccer dribbling circuits for improving physical and psychophysiological responses within secondary school students.

Exercise and sport practitioners frequently utilize rating of perceived exertion (RPE) to evaluate the players' psychophysiological strains during training sessions. The subjective rating of physical exertion level during sports training has been shown to have a reciprocal relationship with wellness status during periodic training or competitive seasons. However, the relationship between subjective physical exertions and wellness status during short-term overseas training camps (OTCs) has not been extensively investigated. This study aimed to examine the perceived responses of physical exertions [session-RPE (sRPE), training monotony, and training strain] and wellness status (fatigue, sleep, delayed onset muscle soreness, stress, and mood) measures in elite young adult futsal players from four separate OTCs with different training tasks. Twenty-seven U-20 male national team futsal players voluntarily participated in this study. The players recruited for OTCs were based on their performance during domestic training camps and the tactical demand of the team. The task of each OTCs was defined as: 1) 1st OTC = game-based camp (n = 14); 2) 2nd and 3rd OTC = training-based camp (n = 20 and n = 17, respectively); and 3) 4th OTC = pre-tournament camp (n = 14). The OTCs consisted of 11 training sessions (18.9 hours) and 16 friendly matches (23.8 hours). During daily training sessions and friendly matches, sRPE was used to quantify training load (TL). Additionally, a five-elements general wellness questionnaire was used to evaluate daily wellness status in the morning. The results demonstrated that the mean and sum sRPE in the game-based OTCs were significantly lower compared to the mean sRPE [p < 0.01, effect size (ES) = -4.8; p < 0.01, ES = -2.9] and sum sRPE in the training-based OTCs (p < 0.01, ES = -3.6; p < 0.01, ES = -3.1). The mean (p = 0.01; ES = -2.0) and sum sRPE (p < 0.01; ES = -3.4) in the game-based OTC were also lower than that in the pre-tournament OTC. Conversely, the wellness scores in the game-based OTC were higher compared to the training-based (p = 0.01; ES = 1.8) and the pre-tournament OTCs (p < 0.01; ES = 1.6). There was a negative relationship between mean and sum sRPE and all wellness scores (mean sRPE = r = -0.441 ~ -0.575, p < 0.001; sum sRPE = r = -0.41 ~ -0.559, p < 0.001). Our findings suggested that responses to training sessions, derived from mean and sum sRPE and wellness scores, are dependent upon the task-specific nature of OTCs among elite futsal players. Utilization of mean and sum sRPE and wellness measures to monitor the psychophysiological health during short-term OTCs is recommended., Competing Interests: The authors have declared that no competing interests exist.

The purpose of this study is to review the existing literature on chronic effects of foam rolling (FR) on flexibility and performance. Electronic databases were searched during January 2022 for topics related to FR. Included studies met the following criteria: (a) peer-reviewed articles written in English; (b) FR intervention of at least four weeks; (c) non-motorized FR device during intervention; (d) randomized controlled trial with existence of a control group; and (e) any lower body parameter related to flexibility, recovery, and performance. Nine studies met that criteria. Results revealed that chronic FR demonstrated conflicting results for improvement of flexibility. On the other hand, a majority of the articles in this review showed no beneficial effects of FR on performance. Lastly, the effect of FR on recovery is unclear. These findings suggest the need for further studies to establish the consensus about the long-term application of FR in flexibility, recovery, and performance.

Objective: Our objective was to explore the training-related knowledge, beliefs, and practices of athletes and the influence of lockdowns in response to the coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)., Methods: Athletes (n = 12,526, comprising 13% world class, 21% international, 36% national, 24% state, and 6% recreational) completed an online survey that was available from 17 May to 5 July 2020 and explored their training behaviors (training knowledge, beliefs/attitudes, and practices), including specific questions on their training intensity, frequency, and session duration before and during lockdown (March-June 2020)., Results: Overall, 85% of athletes wanted to "maintain training," and 79% disagreed with the statement that it is "okay to not train during lockdown," with a greater prevalence for both in higher-level athletes. In total, 60% of athletes considered "coaching by correspondence (remote coaching)" to be sufficient (highest amongst world-class athletes). During lockdown, < 40% were able to maintain sport-specific training (e.g., long endurance [39%], interval training [35%], weightlifting [33%], plyometric exercise [30%]) at pre-lockdown levels (higher among world-class, international, and national athletes), with most (83%) training for "general fitness and health maintenance" during lockdown. Athletes trained alone (80%) and focused on bodyweight (65%) and cardiovascular (59%) exercise/training during lockdown. Compared with before lockdown, most athletes reported reduced training frequency (from between five and seven sessions per week to four or fewer), shorter training sessions (from ≥ 60 to < 60 min), and lower sport-specific intensity (~ 38% reduction), irrespective of athlete classification., Conclusions: COVID-19-related lockdowns saw marked reductions in athletic training specificity, intensity, frequency, and duration, with notable within-sample differences (by athlete classification). Higher classification athletes had the strongest desire to "maintain" training and the greatest opposition to "not training" during lockdowns. These higher classification athletes retained training specificity to a greater degree than others, probably because of preferential access to limited training resources. More higher classification athletes considered "coaching by correspondence" as sufficient than did lower classification athletes. These lockdown-mediated changes in training were not conducive to maintenance or progression of athletes' physical capacities and were also likely detrimental to athletes' mental health. These data can be used by policy makers, athletes, and their multidisciplinary teams to modulate their practice, with a degree of individualization, in the current and continued pandemic-related scenario. Furthermore, the data may drive training-related educational resources for athletes and their multidisciplinary teams. Such upskilling would provide athletes with evidence to inform their training modifications in response to germane situations (e.g., COVID related, injury, and illness)., (© 2021. The Author(s).)

There seems to be a scarcity in literature investigating day-to-day warm-up (WU) variations. We investigated day-to-day variation of psychophysiological responses during Fédération Internationale de Football Association (FIFA) 11 + and dynamic warm-up (DWU) exercises. Twenty-one male collegiate soccer players were randomly assigned to the FIFA 11 + (n = 10) or DWU group (n = 11). Each group performed the assigned WU protocol on three different occasions with a 48-h interval in between. The inter-day variation of the heart rate (HR), time distribution of HR zones, heart rate variability (HRV), estimated energy expenditure (EE), blood lactate (BL) concentration, and the Borg rating of perceived exertion (RPE) were recorded. A two-way repeated measures of analysis of variance was used to compare the differences in chosen variables [group (2) × day (3)]. The coefficient of variation was used to determine the dispersion of the variables over the sessions. The interclass correlation coefficient (ICC) with a two-way random model and a single measure (ICC 2,1 ) was used to determine inter-day reliability. There were no significant differences in time spent at particular HR zones and EE in both groups. The FIFA 11 + exercises showed high reliability of exercise duration, average HR (HR average ), minimal HR (HR min ), peak HR (HR peak ), and post-exercise RPE. In the DWU group, high reliability was found only in HR average , HR peak , and post-exercise RPE. The FIFA 11 + exercises showed similar EE, exercise HR patterns, BL, and RPE compared to the DWU. The FIFA 11 + program is an intense WU protocol with a characteristically low variation of day-to-day exercise HR and RPE responses., (© 2022 Yi-Wen Chiu, Filipe Manuel Clemente, Pedro Bezerra, Jeffrey Cayaban Pagaduan, Yung-Sheng Chen, published by Sciendo.)

To date, there is no quantitative review examining the influence of heart rate variability biofeedback (HRV BFB) on the athlete population. Such an undertaking may provide valuable information on the autonomic and respiration responses of athletes when performing HRV BFB. Thus, purpose of this preliminary systematic review and meta-analysis on the effects of HRV BFB on HRV and respiration of athletes. Searches of Springerlink, SportDiscus, Web of Science, PROQUEST Academic Research Library, Google Scholar, and ScienceDirect were conducted for studies that met the following criteria: (1) experimental studies involving athletes that underwent randomized control trial; (2) availability of HRV BFB as a treatment compared with a control (CON)/placebo (PLA); (3) any pre and post HRV variable and/or breathing frequency as dependent variable/s; and, (4) peer-reviewed articles written in English. Four out of 660 studies involving 115 athletes (25 females and 90 males) ages 16-30 years old were assessed in this review. Preliminary findings suggest the promising ability of HRV BFB to improve respiratory mechanics in athlete population. More work is needed to determine the autonomic modulatory effect of HRV BFB in athletes., (© 2021 Walter de Gruyter GmbH, Berlin/Boston.)

Background: Monitoring the daily change in resting heart rate variability (HRV) can provide information regarding training adaptation and recovery status of the autonomic nervous system (ANS) during training camps. However, it remains unclear whether postural stabilization is essential for valid and reliable ultra-short-term (HRV UST ) recordings in short-term overseas training camps. Design: Observational and longitudinal study. Purpose: This study aimed to investigate ultra-short-term heart rate variability recordings under stabilization or post-stabilization periods in four overseas training camps. Participant: Twenty-seven U-20 male national team futsal players voluntarily participated in this study. Method: Resting HRV was evaluated for 10 min during the early morning of each training camp. The natural logarithm of the root mean square of successive normal-to-normal interval differences (LnRMSSD) was used for comparisons. Time segments of HRV were divided into two periods with three measures within each: (1) the first 30-s (1st&#95;30 s LnRMSSD), the first 60-s (1st&#95;60 s LnRMSSD), and the 5-min standard (1st&#95;5 min LnRMSSD) during stabilization; (2) the first 30-s (2nd&#95;30 s LnRMSSD), the first 60-s (2nd&#95;60 s LnRMSSD), and the 5-min standard (2nd&#95;5 min LnRMSSD) after stabilization. Result: The results demonstrated trivial to small ES (-0.03; 0.46), very large to nearly perfect ICC (0.76; 0.98), and narrow range of SEM (0.06; 0.31) when all time segments of HRV UST were compared to the 1st&#95;5 min and 2nd&#95;5 min HRV. Furthermore, the magnitude of the correlation coefficients ranged from very high to nearly perfect for all the time segments ( r = 0.83; 0.97). The HRV UST posted excellent agreement in all time segments (bias = -0.05; 0.12) with/without postural stabilization. Trivial to small levels of effect size in all time segments of LnRMSSD mean (0.02; 0.41 ES) and LnRMSSD cv (-0.49; -0.02 ES) across overseas training camps was identified. Conclusion: The first 30 or 60-s LnRMSSD recordings can be used to evaluate daily cardiac-autonomic function during overseas training camps in futsal players. The process for stabilization seems to be unnecessary for measuring the morning resting LnRMSSD in overseas training camps among young adult futsal players., 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., (Copyright © 2021 Chen, Pagaduan, Bezerra, Crowley-McHattan, Kuo and Clemente.)

Heart rate variability biofeedback (HRV BFB) is paced breathing scheme that stimulates resonance in the cardiovascular system. This study aimed to investigate the effect of a single-session HRV BFB on Hoffman reflex (H-reflex) of the soleus muscle. Twelve healthy males (height: 173.7 ± 7.18 cm; weight: 72.7 ± 17.7 kg; age: 24.0 ± 5.02 yrs) completed a randomized-crossover intervention involving a 10-minute HRV BFB and normal breathing (CON) separated by 48 hours. Results revealed significantly lower 1a afferent activation after HRV BFB. Similarly, the HRV BFB also demonstrated lower proportion of activated motor neurons from 1a afferents. In conclusion, an acute HRV BFB influenced the reduction in motoneuron excitability at resting condition., (© 2021 Jeffrey Cayaban Pagaduan, Sam Shi Xuan Wu, James William Fell, Yung-Sheng Chen, published by Sciendo.)

Background: Smartphone apps for heart rate variability (HRV) measurement have been extensively developed in the last decade. However, ultra-short-term HRV recordings taken by wearable devices have not been examined., Objective: The aims of this study were the following: (1) to compare the validity and reliability of ultra-short-term and short-term HRV time-domain and frequency-domain variables in a novel smartphone app, Pulse Express Pro (PEP), and (2) to determine the agreement of HRV assessments between an electrocardiogram (ECG) and PEP., Methods: In total, 60 healthy adults were recruited to participate in this study (mean age 22.3 years [SD 3.0 years], mean height 168.4 cm [SD 8.0 cm], mean body weight 64.2 kg [SD 11.5 kg]). A 5-minute resting HRV measurement was recorded via ECG and PEP in a sitting position. Standard deviation of normal R-R interval (SDNN), root mean square of successive R-R interval (RMSSD), proportion of NN50 divided by the total number of RR intervals (pNN50), normalized very-low-frequency power (nVLF), normalized low-frequency power (nLF), and normalized high-frequency power (nHF) were analyzed within 9 time segments of HRV recordings: 0-1 minute, 1-2 minutes, 2-3 minutes, 3-4 minutes, 4-5 minutes, 0-2 minutes, 0-3 minutes, 0-4 minutes, and 0-5 minutes (standard). Standardized differences (ES), intraclass correlation coefficients (ICC), and the Spearman product-moment correlation were used to compare the validity and reliability of each time segment to the standard measurement (0-5 minutes). Limits of agreement were assessed by using Bland-Altman plot analysis., Results: Compared to standard measures in both ECG and PEP, pNN50, SDNN, and RMSSD variables showed trivial ES (<0.2) and very large to nearly perfect ICC and Spearman correlation coefficient values in all time segments (>0.8). The nVLF, nLF, and nHF demonstrated a variation of ES (from trivial to small effects, 0.01-0.40), ICC (from moderate to nearly perfect, 0.39-0.96), and Spearman correlation coefficient values (from moderate to nearly perfect, 0.40-0.96). Furthermore, the Bland-Altman plots showed relatively narrow values of mean difference between the ECG and PEP after consecutive 1-minute recordings for SDNN, RMSSD, and pNN50. Acceptable limits of agreement were found after consecutive 3-minute recordings for nLF and nHF., Conclusions: Using the PEP app to facilitate a 1-minute ultra-short-term recording is suggested for time-domain HRV indices (SDNN, RMSSD, and pNN50) to interpret autonomic functions during stabilization. When using frequency-domain HRV indices (nLF and nHF) via the PEP app, a recording of at least 3 minutes is needed for accurate measurement., (©Yung-Sheng Chen, Wan-An Lu, Jeffrey C Pagaduan, Cheng-Deng Kuo. Originally published in JMIR mHealth and uHealth (http://mhealth.jmir.org), 31.07.2020.)

This systematic review was conducted to evaluate the effect of heart rate variability biofeedback (HRV BFB) on performance of athletes. Six electronic databases (Springerlink, SportDiscus, Web of Science, PROQUEST Academic Research Library, Google Scholar, and ScienceDirect) and article references were searched. Eligibility criteria were: 1. experimental studies involving athletes randomly allocated among groups (randomized control trial); 2. availability of HRV BFB as a treatment compared to a control condition (CON) that involves regular sport/dance training, a placebo (PLA) or other methods of BFB; 3. performance-related variables such as a dependent index; and, 4. peer-reviewed articles written in English. Out of 660 articles, six studies were included in the systematic review which involved 187 athletes (females: n = 89; males n = 98). Six studies compared HRV BFB with a CON, three studies compared HRV BFB with a PLA, and two studies differentiated HRV BFB with other methods of BFB. Findings support HRV BFB as a potential intervention to improve fine and gross motor function in athletes., (© 2020 Jeffrey Cayaban Pagaduan, Yung-Sheng Chen, James William Fell, Sam Shi Xuan Wu, published by Sciendo.)

The aim of the present study was to compare the effects of different warm-up interventions on jump, sprint and agility performance in collegiate soccer players. Twenty-one healthy male college soccer players (age: 20.14 ± 1.65 years; body height: 179.9 ± 8.34 cm; body mass: 74.4 ± 13.0 kg; % body fat: 9.45 ± 4.8) participated in the study. Subjects underwent four different randomized warm-up protocols separated by at least 48 hours. The warm-up schemes were: 1. no conditioning contraction protocol (NCC); 2. dynamic stretching (DS); 3. prolonged intermittent low-intensity isometric exercise (ST); and, 4. ST with an additional external load equal to 30% of body weight (ST + 30% BW). All interventions were preceded by a general warm-up. Results from one-way repeated measures ANOVA demonstrated a significant difference in countermovement jump (CMJ) at F(3,60) = 10.2, ηρ(2) = 0.337, p < 0.01. Post hoc analysis revealed a significant difference in CMJ performance in DS when compared to NCC and ST + 30% BW. No significant difference in CMJ was observed between DS and ST. CMJ scores in NCC, ST, and ST + 30% BW were non-significant. There was a significant difference in speed; F(3, 60) = 6.61, ηρ(2) = 0.248, p < 0.01. Post hoc analysis revealed significantly better time in DS than NCC and ST. However, no difference in speed was observed between DS and ST + 30% BW. Similarly, speed was similar in NCC, ST and ST + 30% BW. A significant difference in agility performance was also observed; F(3, 60) = 24.1, ηρ(2)= 0.546, p < 0.01. Post hoc analysis revealed significantly greater performance gains in DS than NCC. No significant difference in agility was observed in DS, ST and ST + 30% BW. In conclusion, a prolonged intermittent low-intensity isometric protocol using bodyweight only showed similar benefits with dynamic stretching in countermovement jump performance. When the same isometric condition with additional load equal to 30% of bodyweight was applied, effects in speed and agility were similar to dynamic stretching.

The purpose of this study was to identify the effects of warm-up strategies on countermovement jump performance. Twenty-nine male college football players (age: 19.4 ± 1.1 years; body height: 179.0 ± 5.1 cm; body mass: 73.1 ± 8.0 kg; % body fat: 11.1 ± 2.7) from the Tuzla University underwent a control (no warm-up) and different warm-up conditions: 1. general warm-up; 2. general warm-up with dynamic stretching; 3. general warm-up, dynamic stretching and passive stretching; 4. passive static stretching; 5. passive static stretching and general warm-up; and, 6. passive static stretching, general warm-up and dynamic stretching. Countermovement jump performance was measured after each intervention or control. Results from one way repeated measures ANOVA revealed a significant difference on warm-up strategies at F (4.07, 113.86) = 69.56, p < 0.001, eta squared = 0.72. Bonferonni post hoc revealed that a general warm-up and a general warm-up with dynamic stretching posted the greatest gains among all interventions. On the other hand, no warm-up and passive static stretching displayed the least results in countermovement jump performance. In conclusion, countermovement jump performance preceded by a general warm-up or a general warm-up with dynamic stretching posted superior gains in countermovement jump performance.