Upper and lower limb bone mass accrual in adolescent footballers across a short period of training and competition

Abstract Objectives: To analyze bone mineral content (BMC) and area bone mineral density (aBMD) accrual in adolescent male footballers who started their first football season. Methods: 17 athletes (14.8 ± 0.4 years) were monitored across 15 weeks of football training. Participants were evaluated for somatic maturation (HPHV), BMC, and aBMD at three time points: before (M1) and after (M2) a preparatory phase, and at the end of the competitive phase (M3). BMC and aBMD were measured using DXA scans. Participants were divided into groups according to maturation status (circa-PHV and post-PHV), and the amount of accumulated training load (median split). Results: A significant effect (12.1 g/week, standard error (SE) = 2.6 g/week) was observed for lower limbs BMC across the three time points. There were no significant effects of time for upper limbs BMC. There was a significant effect of time for total body aBMD (0.007, SE = 0.003 g/cm2/week) across the three time points. Adolescents at post-PHV had a significant 245.6 g (SE = 56.1 g) higher BMC compared to adolescents at circa-PHV. No significant effects were observed for the accumulated training load. Conclusion: Systematic football training, even during the growth spurt, has a positive impact on adolescent bone markers despite the accumulated training load and maturation.

Effect of High-Intensity Interval, Moderate-Intensity Continuous, and Self-Selected Intensity Training on Health and Affective Responses.

Purpose: To compare the effects of 12-week high-intensity interval (HIIT), moderate-intensity continuous (MICT), and self-selected intensity training (SSIT) on health outcomes and affective responses. Methods: Seventy-three overweight/obese inactive adults (62% woman; age, 31.4 ± 7.2 years; height, 1.66 ± 0.09 cm; Body mass index, 28.9 ± 2.7 kg.m-2) who were randomized into HIIT (n = 23), MICT (n = 24) and SSIT (n = 26) groups. The training was conducted three times per week in an outdoor environment, with 4 weeks under direct supervision and 8 weeks with semi-supervision. Cardiorespiratory fitness, body composition, and metabolic profile were evaluated at baseline and at the end of the 4th and 12th weeks. Core affect was measured during all training sessions. Results: Peak oxygen uptake improved in all groups after 4 and 12 weeks compared with baseline. Only the SSIT had reductions in body fat throughout the intervention. No improvements were observed in the metabolic profile across all groups. SSIT was perceived as more pleasurable than HIIT; however, there were no differences in affective responses between SSIT and MICT. Affective responses in-task (e.g. negative and positive peak, rate of change and affect at the end of the exercise session) predicted the HIIT and SSIT exercises attendance rate. Conclusion: Regardless of the exercise training protocol, overweight/obese inactive adults improved health outcomes, which suggests the prescribing HIIT, MICT, and SSIT in outdoor environments. SSIT should be considered in order to optimize the pleasure during training sessions. Affective response more positive in-task of the HIIT and SSIT is associated with greater attendance rate in these exercise protocols.

Upper and lower limb bone mass accrual in adolescent footballers across a short period of training and competition.

OBJECTIVES: To analyze bone mineral content (BMC) and area bone mineral density (aBMD) accrual in adolescent male footballers who started their first football season. METHODS: 17 athletes (14.8 ± 0.4 years) were monitored across 15 weeks of football training. Participants were evaluated for somatic maturation (HPHV), BMC, and aBMD at three time points: before (M1) and after (M2) a preparatory phase, and at the end of the competitive phase (M3). BMC and aBMD were measured using DXA scans. Participants were divided into groups according to maturation status (circa-PHV and post-PHV), and the amount of accumulated training load (median split). RESULTS: A significant effect (12.1 g/week, standard error (SE) = 2.6 g/week) was observed for lower limbs BMC across the three time points. There were no significant effects of time for upper limbs BMC. There was a significant effect of time for total body aBMD (0.007, SE = 0.003 g/cm2/week) across the three time points. Adolescents at post-PHV had a significant 245.6 g (SE = 56.1 g) higher BMC compared to adolescents at circa-PHV. No significant effects were observed for the accumulated training load. CONCLUSION: Systematic football training, even during the growth spurt, has a positive impact on adolescent bone markers despite the accumulated training load and maturation.

Low-Volume High-Intensity Interval Training Sessions With Different Work-Recovery Durations and Muscle Damage in Trained Men.

Purpose: This study compared the effect of low-volume high-intensity training (LV-HIIT) sessions with different work-recovery durations on muscle damage markers.Methods: Twenty-four trained adult males (22.3 ± 2.9 years; 24.6 ± 2.7 kg∙m-2) performed two LV-HIIT sessions (10 x 60 s and 20 x 30 s at 100% of maximal aerobic speed on treadmill (Vmax) interspersed with equal time passive recovery, respectively) in a randomized, counter-balanced order, separated by a 1-week interval. Delayed onset muscle soreness (DOMS) and countermovement vertical jump height (CVJH) performance were assessed before, and 24-h and 48-h post sessions.Results: Pressure-pain threshold (PPT), pressure-pain tolerance (PPTol) and perceived pain intensity (PPI) using pressure algometry assessed DOMS in the rectus rectus femoris, biceps femoris and gastroctemius. A non-significant session by time interaction for PPT, PPTol and PPI in all muscles analyzed was observed (all P > 0.260). Additionally, a non-significant session by time interaction was observed for CVJH performance (P = 0.836).Conclusion: LV-HIIT sessions with different work-recovery durations elicited non-significant changes on muscle damage markers following 24- and 48-h in trained males.

Effects of Training Loads on Stress Tolerance and Mucosal Immunity in High-Intensity Functional Fitness Athletes.

Purpose: This study aimed to analyze the effects of training load on stress tolerance (ST) and secretory immunoglobulin A (SIgA) in male and female high-intensity functional fitness (HIFF) athletes during two different 10 and consecutive weekly training volume loads [higher (week 1) and lower volume (week 2)]. Methods: 14 athletes [7 males: 29.3 (±5.8) years; 86.3 (±8.2) kg and 176.8 (±3.8) cm and 7 females: 32.7 (±4.4) years; 60.0 (±6.7) kg and 162.5 (±5.9) cm] participated. The ST, assessed by Daily Analysis of Life Demand in Athletes questionnaire (DALDA) and Saliva sampling were performed in four time-points (pre (T1) and post (T2) week 1; pre (T3) and post (T4) week 2). Results: Female athletes showed a decrease in ST (symptoms of stress) from 15 T1 to T3 [F(3,36) = 7.184, p˂ 0.001, ηp2 = 0.374], without difference in male athletes (p > .05). There is a significant difference of SIgA concentration [F(3.36) = 3.551; p = .024; ηp2 = 0.228], with a significant decrease in female athletes group in T2 compared to T1 (p = .013) and T4 (p = .023). In addition, the different training volume loads did not impact mucosal immunity in male athletes (p > .05). Conclusion: The current findings suggest that higher HIFF volume results in decreased ST and SIgA concentration in female 20 athletes and a subsequent decrease in training volume loads contributed to restoring these variables.

The Influence of Different Training Load Magnitudes on Sleep Pattern, Perceived Recovery, and Stress Tolerance in Young Soccer Players.

ABSTRACT: Ferreira, ABdM, Ribeiro, BLL, Batista, EdS, Dantas, MP, and Mortatti, AL. The influence of different training load magnitudes on sleep pattern, perceived recovery, and stress tolerance in young soccer players. J Strength Cond Res 37(2): 351-357, 2023-The aim of this study was to analyze the influence of 3 weeks on sleep parameters, perceived recovery, and stress tolerance in young soccer players using different training load magnitudes. A total of 13 young male soccer athletes (15.9 ± 0.5 years; 68.7 ± 6.1 kg; 170 ± 7 cm) who performed 3 typical training weeks with different workloads were analyzed. The external training load (ETL) was verified by the PlayerLoad method, and the internal training load (ITL) was determined using the session rating of perceived exertion method. Sleep was monitored using a wrist-actigraphy monitor. Sleep variables, including total time in bed (TTB), total sleep time (TST), sleep latency (SL), wake after sleep onset (WASO), and sleep efficiency (SE), were evaluated across all nights of sleep. The recovery status was assessed with the perceived recovery status (PRS) scale, and the stress tolerance was monitored using the "daily analysis of life demands of athletes" questionnaire. There was an increase in sleep time during the week with the highest training load (week 2) (TTB: +35 minutes, TST: +46 minutes, SL: -5 minutes, SE: +3%). There was no difference in the PRS or in the stress tolerance during the evaluation weeks. A very large within-individual correlation was observed between ITL and ETL ( r = 0.78) and moderate within-individual correlation between ETL and TST ( r = 0.34), between ITL and TST ( r = 0.45), and between ITL and SE ( r = 0.359). These results showed that there was an increase in TST during a microcycle with intensified loads, without impairing bedtime and resulting in maintenance of the perceived recovery or stress tolerance values.

Analysis of stress tolerance, competitive-anxiety, heart rate variability and salivary cortisol during successive matches in male futsal players.

BACKGROUND: This study aimed to compare the stress tolerance, competitive anxiety, heart rate variability and salivary cortisol before and during successive futsal competitive matches (3 matches in 4 days) in young male futsal players. METHODS: 10 young male futsal players (16.9 ± 0.7 age; 71.0 ± 5.1 kg; 174.9 ± 4.3 cm) were monitored during one training session and across a competitive period with 3 successive matches. External load was determined by the PlayerLoad method, while session rating of perceived exertion was used to calculate the internal training and competitive load. The stress tolerance was examined using Daily Analysis of Life Demand in Athletes questionnaire and the Competitive State Anxiety Inventory was used to analyze the competitive anxiety. The Time and frequency monitoring parameters were used to analyze the vagal cardiac autonomic marker. sC was analyzed using enzyme-linked immunosorbent assay. RESULTS: A generalized estimating equation showed a significant difference for PlayerLoad from M1 to TS, M2 and M3, from M2 to M3 (p < 0.05), and for session rating of perceived exertion from M1 to Ts and M3 (p < 0.05). A difference for sources [χ2 (3) = 1.481, p = 0.68] or symptoms [χ2 (3) = 3.893, p = 0.27] was not found. There was no significant difference in any of the competitive anxiety [cognitive anxiety (F (1.644; 14.799) = 4.6, p = 0.73, ŋ2 p = 0.28), somatic anxiety (F (2,09; 18,85) = 26.07 p = 0.057; ŋ2p = 0.27) or self-confidence (F(2.07; 18.85) = 15.875 p = 0.152; ŋ2p = 0.18)] domains. The HRV parameters (time domain and frequency) and Salivary Cortisol (sC) (χ2 (3) = 4.320 p = 0.229) did not significantly change during the successive matches. CONCLUSION: The competitive scenario in which the players were evaluated did not significantly modify the stress tolerance, or the athletes' state of anxiety, which in turn was not able to promote changes in the cardiac vagal modulation or in the sC levels before the matches.

Short-Term Effects of Repeated-Sprint Training on Vertical Jump Ability and Aerobic Fitness in Collegiate Volleyball Players During Pre-Season.

The aim of this study was to assess the effect of repeated-sprint training (RST) on vertical jump ability and aerobic power in college volleyball players. Nineteen male volleyball players, aged between 18-24 years, were randomized into the RST group (RST; n = 10) and control group (CG; n = 9). The RST included 2-3 sets of 6×30m all-out sprints, twice per week, in addition to the regular training routine. The control group performed only the regular volleyball training sessions (i.e. mainly of technical-tactical drills). All players performed a maximal graded treadmill test, vertical countermovement jump (CMJ), and repeated-vertical jump ability (RVJA) test before and after 6-weeks of the training program. The following variables were determined from the RVJA: peak (RVJApeak), average (RVJAmean), and rate of decrement (RVJADec). A two-way ANOVA with repeated measures showed an interaction effect on CMJ (F (1,17) = 6.92; p = 0.018; η 2 = 0.289), RVJApeak (F (1,17) = 4.92; p = 0.040; η 2 = 0.225), maximal oxygen uptake (F (1,17) = 9.29; p = 0.007; η 2 = 0.353) and maximal speed attained in the treadmill test (F (1,17) = 8.66; p = 0.009; η 2 = 0.337), with significant improvements only on the RST group. In conclusion, RST, twice per week, improved RVJA and aerobic power in comparison to regular skill-based volleyball training.

Effect of Fatigue and Graded Running on Kinematics and Kinetics Parameters in Triathletes.

This study aimed to evaluate the effect of cycling-induced fatigue on subsequent running with different ground inclinations on triathletes. Twenty male triathletes ran on a treadmill at individual speeds, on three inclines: level (0%), 7% uphill (7%), and 7% downhill (-7%). Subsequently, the athletes performed an incremental ramp-to-exhaustion (RTE) protocol on an ergometric bicycle until task failure and repeated the running protocol (POST-RTE). During running and cycling was monitored perceived exertion (RPE) and heart rate (HR). Plantar pressure distribution, peak plantar pressure, total foot area, and ground contact time were measured by an in-shoe sensor. Analysis of variance showed that HR (p=0.001; η2=0.63) and RPE (p=0.001; η2=0.82 large effect) were higher in POST-RTE, without interactions between slopes and fatigue. The heel load showed difference between 0 and 7% and 7 and -7% (p=0.001; η 2=0.44 large effect) with higher value in -7%. The midfoot showed differences between 0 and -7% with higher value in 0% (p=0.03; η 2=0.15 small effect). The contact time showed interactions between fatigue and slopes with a higher value in POST-RTE. Coaches should be aware that training on the uphill and downhill surfaces can alter the plantar load on different foot parts.

Agreement between upper and lower limb measures to identify older adults with low skeletal muscle strength, muscle mass and muscle quality.

BACKGROUND: Identifying low skeletal muscle strength (SMS), skeletal muscle mass (SMM) and skeletal muscle quality (SMQ) is pivotal for diagnosing sarcopenia cases. Age-related declines in SMS, SMM, and SMQ are dissimilar between the upper (UL) and lower limbs (LL). Despite this, both UL and LL measures have been used to assess SMS, SMM and SMQ in older adults. However, it is not clear whether there is agreement between UL and LL measures to identify older adults with low SMS, SMM and SMQ. OBJECTIVE: To investigate the agreement between UL and LL measures to identify older adults with low SMS, SMM and SMQ. METHODS: Participants (n = 385; 66.1 ± 5.1 years; 75,4% females) performed the handgrip strength test (HGS) and the 30-s chair stand test (CST) to assess UL- and LL-SMS, respectively. The SMM was assessed by dual-energy X-ray absorptiometry (DXA). The UL-SMQ was determined as: handgrip strength (kgf) ÷ arm SMM (kg). LL-SMQ was determined as: 30-s CST performance (repetitions) ÷ leg SMM (kg). Results below the 25th percentile stratified by sex and age group (60-69 and 70-80 years) were used to determine low SMS, SMM and SMQ. Cohen's kappa coefficient (κ) was used for the agreement analyses. RESULTS: There was a slight and non-significant agreement between UL and LL measures to identify older adults with low SMS (κ = 0.046; 95% CI 0.093-0.185; p = 0.352). There was a moderate agreement to identify low SMM (κ = 0.473; 95% CI 0.371-0.574; p = 0.001) and a fair agreement to identify low SMQ (κ = 0.206; 95% CI 0.082 to 0.330; p = 0.005). CONCLUSION: The agreement between UL and LL measures to identify older adults with low SMS, SMM and SMQ is limited, which might generate different clinical interpretations for diagnosing sarcopenia cases.

Effects of Integrative Neuromuscular Training on Motor Performance in Prepubertal Soccer Players.

ABSTRACT: Menezes, GB, Alexandre, DR, Pinto, JC, Assis, TV, Faigenbaum, AD, and Mortatti, AL. Effects of integrative neuromuscular training on motor performance in prepubertal soccer players. J Strength Cond Res 36(6): 1667-1674, 2022-The present study examined the effects of integrative neuromuscular training (INT) on motor performance in prepubertal soccer players. Subjects were randomly assigned to the experimental group (INT; n = 20, age: 8.2 ± 1.2 years; body mass: 28.4 ± 6.4 kg; height: 1.3 ± 0.1 m) or the control group (CON; n = 18, age: 8.5 ± 1.3 years; body mass: 32.8 ± 8.9 kg; height: 1.3 ± 0.1 m). Integrative neuromuscular training program was performed twice per week during the 12-week training intervention. Balance, flexibility, countermovement vertical jump height (CVJH), sprint speed, and change of direction speed (CODS) were assessed in both groups at baseline, sixth week and 12th week. A mixed model repeated measures analysis of variance was used to examine the group changes in performance for each variable. There was a time effect for balance in the INT from pre to 12th weeks (p < 0.001, g = 0.72), and from 6th to 12th weeks (p = 0.005, g = 0.34). An interaction effect for balance was also observed between INT and CON after the 12th week. A time effect in flexibility was observed in INT from baseline to 6th and 12th weeks (p = 0.02; g = 0.45 and p < 0.001; g = 0.71) and from 6 to 12th weeks (p = 0.003; g = 0.24). There was a time effect in CVJH, from baseline to 12th week and from 6th to 12th weeks (p < 0.05; g = 0.34 and g = 0.53, respectively). There was no significant between-group speed performance change. A time effect was found in CODS in INT, but only from baseline to 12th week (p = 0.02; g = 0.31). There were significant improvements in the percent change (Δ%) from baseline to 12 weeks (p < 0.05) for balance, flexibility, and CVJH in INT. These findings indicate that the addition of an INT program to soccer practice can improve selected motor performance skills in prepubertal soccer players.

A Congested Match Schedule Alters Internal Match Load and Affects Salivary Immunoglobulin A Concentration in Youth Soccer Players.

ABSTRACT: Mortatti, AL, Oliveira, RSCd, Pinto, JCBdL, Galvão-Coelho, NL, Almeida, RN, Aoki, MS, and Moreira, A. A congested match schedule alters internal match load and affects salivary immunoglobulin A concentration in youth soccer players. J Strength Cond Res 36(6): 1655-1659, 2022-The aim of this study was to analyze the effects of a congested match schedule (CMS) undertaken after a tapering week, on internal match load (IML) and salivary immunoglobulin A (SIgA) concentration in 12 youth soccer players (16.6 ± 0.5 years; 175 ± 8 cm; 65 ± 8 kg) who performed 4 official matches within a 4-day period. Internal match load was determined using the session-rating of perceived exertion method and the competitive strain (CS) and monotony index (MI) were also determined. Saliva sampling was conducted, before the last training day of a tapering week (training) preceding the CMS, 60 minutes before the first match (match-1), and 22 hours after match 4 (postmatch 4). Salivary immunoglobulin A was analyzed by ELISA. The results of the analysis of variance with repeated measures showed a significant difference for IML across the matches (p < 0.001). A significant reduction in SIgA was observed from prematch 1 to postmatch 4 (p = 0.019). Regarding the change in SIgA (ΔSIgA), 58.3% of the players presented values equal/higher than the minimal detectable change. A large within-individual correlation was observed between ΔSIgA and MI and CS (r = 0.71 and r = 0.72: p < 0.01, respectively). The current findings suggest that youth players participating in a CMS may present a decrease in mucosal immunity function. In addition, data suggest that the MI and CS may be used as valuable markers for monitoring competition load during CMS in youth soccer players.

The Effects of Successive Soccer Matches on the Internal Match Load, Stress Tolerance, Salivary Cortisol and Jumping Performance in Youth Soccer Players.

The study aim was to analyze the effects of successive matches on the internal match load, stress tolerance, salivary cortisol concentration and countermovement vertical jump height in twelve youth soccer players (16.6 ± 0.5 yr; 175 ± 8 cm; 65 ± 8 kg) who performed four official matches within a four day-period with a 24-h recovery interval between the matches. The internal match load, monotony index and competitive strain, as well as stress tolerance were examined. Saliva samples were collected and countermovement vertical jump height was assessed 60 min pre and 30 min post each match; delta of salivary cortisol and countermovement vertical jump height for each match were analyzed. Salivary cortisol was analyzed using an enzyme-linked immunosorbent assay. The results of ANOVA with repeated measures showed no differences between matches for the internal match load (p > 0.05). The scores of the monotony index and competitive strain were 4.3 (±2.3) and 8104 (±6795) arbitrary units, respectively. There was no difference for stress tolerance between matches (p > 0.05). Delta values of salivary cortisol were not different among the assessed matches (F(3,33) = 1.397, p = 0.351, η2: 0.09); however, delta of countermovement vertical jump height decreased from match 1 to match 4 (F(3,33) = 8.64, p < 0.001, η2: 0.44). The current findings suggest that participating in four successive matches, with 24-h of recovery in between, may not lead to changes in stress tolerance and salivary cortisol of youth players, but it may induce a decrease in players' jumping performance after the fourth match.

Does motor coordination influence perceptual-cognitive and physical factors of agility in young soccer players in a sport-specific agility task?

This study aims to determine whether motor coordination influences the perception-decision time (perceptual-cognitive factor) and movement response time (physical factor) of young soccer players in a sport-specific agility task regardless of maturation. Eighty-seven young male soccer players were analysed. Anthropometric measurements were used to determine the maturity offset, while physical qualities including agility, change of direction speed (CODS) and motor coordination were also assessed. The following variables were obtained from these tests: Motor coordination score, perception-decision time, movement response time, agility time and CODS time. Motor coordination revealed a non-significant correlation with perception-decision time (r = 0.10, p = 0.34). However, motor coordination showed negative and significant correlations with CODS time (r = -0.47, p < 0.01), agility time (r = -0.52, p < 0.01) and movement response time (r = -0.62, p < 0.01). In addition, regression analysis showed that each increase in motor coordination score was associated with significant decreases in agility time (b = -0.023), movement response time (b = -0.021) and CODS time (b = -0.021) independent of maturity offset. The results of this study indicated that motor coordination was significantly related to the physical factors of agility in young soccer players.

Differences in Handgrip Strength-Endurance and Muscle Activation Between Young Male Judo Athletes and Untrained Individuals.

Purpose: The aim of this study was to compare strength-endurance handgrip performance and muscle coactivation between judo athletes and untrained young males. Method: The sample was 38 judo athletes and 38 untrained young males, between 12 and 15 years-old. Maturational status was evaluated by age at peak height velocity. A maximal isometric handgrip test (three 5-s repetitions, with 90-s intervals) and an isometric strength-endurance handgrip test (ten 10-s all-out isometric handgrip repetitions, 20-s intervals) was conducted in dominant (D) and nondominant (ND) hands, using a dynamometer with EMG monitor to detect muscle activation. Results: ANCOVA analysis, controlling for maturational status, showed that judo athletes had higher values of maximal absolute (D = 33.6 ± 8.9 kgf vs 29.1 ± 9.0 kgf; ND = 33.8 ± 9.9 kgf vs 28.1 ± 8.1 kgf) and relative strength to body mass (D = 0.64 ± 0.12 kg/kgf vs 0.57 ± 0.13 kg/kgf; ND = 0.64 ± 0.16 kg/kgf vs 0.56 ± 0.14 kg/kgf). Moreover, judo athletes presented lower strength mean fatigue index (33.2 ± 6.9 % vs 37.9 ± 8.7 %) and muscle coactivation (48 ± 19.8 % vs 57.5 ± 22 %), only in the dominant hand, during the isometric strength-endurance handgrip test. During all repetitions of isometric endurance test there were no group or interaction between factors effects for absolute strength, relative strength and muscle coactivation. Conclusion: In summary, judo athletes present higher maximal absolute and relative strength and strength-endurance performance, concomitantly with decreased muscles co-activation (primary in dominant hand) during handgrip tests.

Effects of Integrative Neuromuscular Training and Detraining on Countermovement Jump Performance in Youth Volleyball Players.

ABSTRACT: Nunes, ACCA, Cattuzzo, MT, Faigenbaum, AD, and Mortatti, AL. Effects of integrative neuromuscular training and detraining on countermovement jump performance in youth volleyball players. J Strength Cond Res 35(8): 2242-2247, 2021-The purpose of this study was to analyze the effect of integrative neuromuscular training (INT) on countermovement vertical jump height (CVJH) performance in youth volleyball players before and after a detraining period. Thirty-two novice volleyball players were cluster randomized into 2 groups: intervention group-INT (age: 13.1 ± 0.4 years; body mass: 55.3 ± 12.1 kg; and height: 161.1 ± 6.4 cm) and control group-CON (age: 12.8 ± 0.7 years; body mass: 51.8 ± 13.6 kg; and height: 160.1 ± 10.7 cm). The subjects were evaluated for somatic maturation (years from peak height velocity) and for CVJH performance at 4 time points during the 20-week study period: baseline, 6 weeks of INT, 12 weeks of INT, and 8 weeks after INT (detraining). The analysis used repeated-measures analysis of variance and Bonferroni post hoc test to identify possible differences in the CVJH delta in both groups. Spearman correlation was performed to verify the association between the values of the vertical jump tests and maturational levels found. The INT showed a significant improvement in the CVJH from baseline to 12 weeks and maintained training-induced gains after detraining period (p > 0.001). Significant increase in CVJH was found in the percentage of change (Δ%) from baseline to 6 weeks (p < 0.005), 12 weeks (p < 0.001), and detraining (p < 0.001) in INT compared with the CON. The results of this study indicate that INT was able to improve CVJH performance in novice youth volleyball players and these gains were sustained during the detraining period. These findings indicate that regular participation in supervised INT can enhance jumping performance in young volleyball players, and that this type of neuromuscular program may be particularly beneficial for youth with limited fundamental motor skill performance.

Do heart rate variability is relationed to endurance performance in female futsal players? / A variabilidade da frequência cardíaca está relacionada ao desempenho de resistência em jogadoras de futsal?

abstract The study aimed to verify the correlation between resting heart rate variability (HRVrest) and endurance performance in female futsal players, as well as to evaluate the reliability of this parasympathetic autonomic marker. A total of 16 female futsal players (age: 22 ± 3 years; VO2max: 42.3 ± 2.0 ml.kg-1.min-1) were evaluated during the first week of preseason training. Vagal modulation was evaluated from the HRVrest (i.e., log-transformed root mean square of successive R-R interval differences - Ln-RMSSD) for two consecutive days, while endurance performance was evaluated by the Yo-Yo Intermittent Recovery Test, Level 1 (Yo-Yo IR1). Pearson correlation was used to analyze the relationship between the variables. Strong correlation between the HRVrest index and endurance performance (r = 0.643; p = 0.007). Reliability was tested through the intraclass correlation coefficient, coefficient of variation (CV), and Bland-Altman analysis of the agreement. Furthermore, acceptable repeatability of HRVrest, but with great inter-subject variability (ICC = 0.670, 95%CI = 0.056-0.885, CV = 15.8%). The current study demonstrated a strong correlation between Ln-RMSSD and endurance performance, and despite the acceptable values of intrasubject reliability, HRVrest presented high inter-individual variability in female futsal players.

resumo O objetivo do estudo foi verificar a correlação entre a variabilidade da frequência cardíaca de repouso (VFCRepouso) e o desempenho de resistência em jogadoras de futsal, bem como avaliar a confiabilidade do marcador parassimpático. No total, 16 jogadoras de futsal (idade: 22 ± 3 anos; VO2max: 42.3 ± 2.0 ml.kg-1.min-1) foram avaliadas durante a primeira semana de treinamento da pré-temporada. A modulação vagal foi avaliada a partir da VFC de repouso (isto é, raiz quadrada da média das diferenças sucessivas ao quadrado dos intervalos R-R adjacentes - Ln-RMSSD) por dois dias consecutivos, enquanto o desempenho da resistência foi avaliado pelo Yo-Yo Intermittent Recovery Test, Level 1 (Yo-Yo IR1). A correlação de Pearson foi utilizada para analisar a relação entre as variáveis. A confiabilidade foi testada através do coeficiente de correlação intraclasse, coeficiente de variação e análise de concordância de Bland-Altman. Observou-se uma forte correlação entre o índice de VFCrepouso e o desempenho de endurance (r = 0,643; p = 0,007). Por outro lado, repetibilidade aceitável dos índices de repouso vagal, mas com grande variabilidade interindividual (ICC = 0,670, IC = 0,056-0,885, CV = 15,8%). O presente estudo apresentou forte correlação entre Ln-RMSSD e desempenho de endurance, e mesmo com valores aceitáveis de confiabilidade intrasujeito, a VFC em repouso apresentou alta variabilidade interindividual em jogadoras de futsal.

Effects of Six Weeks of High-Intensity Functional Training on Physical Performance in Participants with Different Training Volumes and Frequencies.

High-intensity functional training (HIFT) is characterized by presenting high volumes and training intensities with constantly varied exercises. The aim of this study was to analyze the internal training load and the effects of high-intensity functional training on physical performance in subjects with different training volumes and frequencies. A total of 31 volunteers involved in high-intensity functional training (14 men and 17 women) were divided according to their training volumes and frequencies (high training-volume and frequency-HTVF; (n = 17) (nine women and eight men; age: 31.0 ± 6.3 years; height: 168.8 ± 8.1 cm, body weight: 73.6 ± 11.9 kg; BMI: 25.96 kg/m2) and moderate training volume and frequency-MTVF; (n = 14) (eight women and six men; age: 26.6 ± 4.7 years; height: 167.2 ± 8.6 cm, body weight: 75.8 ± 18.0 kg; BMI: 27.33 kg/m2)). The internal training load was determined using the session-rating of perceived exertion method. The monotony index (MI) and training strain (TS) were used to determine training variability during the training weeks. Countermovement vertical jump height, 20-m sprinting and handgrip strength were assessed at baseline and after six weeks of training. There was a time effect for MI ((F(5, 145) = 5.942; p = 0.0001)), TS ((F(5, 145) = 5.734; p = 0.0001)), weekly internal training load ((F(4.006, 116.87) = 4.188; p = 0.003)) and mean weekly internal training load ((F(4.006, 116.87) = 4.188; p = 0.003)). There was no increase in performance in either group for countermovement vertical jump height ((F(1,29) = 6.081; p = 0.050)), sprinting ((F(1,29) = 1.014; p = 0.322)), right handgrip strength ((F(1,29) = 2.522; p = 0.123)) or left handgrip strength ((F(1,29) = 2.550; p = 0.121)). The current findings suggest that six weeks of high-intensity functional training was not able to increase performance in either group. Therefore, different volumes and frequencies do not seem to influence the increase in physical performance of HIFT practitioners.

The effect of smartphones and playing video games on decision-making in soccer players: A crossover and randomised study.

The objective of this study was to analyse the effect of the use of social networks in smartphones or playing video games on the passing decision-making performance in professional soccer athletes. Participants were 25 male professional soccer athletes (mean ± SD: age 23.4 ± 2.8 years). The participants performed three randomised conditions divided into three groups: control (CON), smartphone (SMA), and video game (VID). Before and after each experimental condition, the Stroop Task assessed the level of induced mental fatigue. Then, the athletes performed a simulated soccer match. A CANON® camera recorded the matches for further analysis on passing decision-making performance. A group effect was identified (p < .01) with impairment on passing decision-making performance for the SMA (p = .01, ES = 0.5) and VID (p = .01, ES = 0.5) conditions. We concluded that the use of social networks on smartphones and/or playing video games right before official soccer matches might impair the passing decision-making performance in professional soccer athletes.