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  • Author: Fabio Y. Nakamura x
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Fabio Y. Nakamura, Lucas A. Pereira, César C. Cal Abad, Emerson Franchini and Irineu Loturco

Purpose:

To quantify the training loads reported by karate athletes of the Brazilian national team in the week immediately before their participation in the 2015 Pan American Games.

Methods:

Eleven elite karate athletes (7 men and 4 women, 24.42 ± 3.75 y, 1.70 ± 0.09 m, 69.6 ± 13.2 kg) from the Brazilian national team took part in this study. Session rating of perceived exertion (s-RPE) was quantified in all training sessions. Moreover, resting heart-rate variability (HRV), as analyzed through the natural log of the root-mean-square difference of successive normal RR intervals (lnRMSSD), and countermovement-jump (CMJ) performance before and after 8 training sessions were assessed throughout the week. The differences based on magnitudes were calculated comparing pre- and posttraining session, as well as measures performed every morning during the week.

Results:

The weekly s-RPE was 2608.5 ± 431.2 a.u. The lnRMSSD was very likely higher on Monday than on the following days of the week, remaining stable during this period. CMJ height did not change during the week. Almost certain differences were observed in lnRMSSD pre- and posttraining session, while CMJ height did not change.

Conclusions:

The national karate-team athletes did not present signs of fatigue accumulation, as indicated by relatively steady HRV and unchanged CMJ during the week, as planned by the coaches for precompetition technical and tactical refinement.

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Lucas A. Pereira, Andrew A. Flatt, Rodrigo Ramirez-Campillo, Irineu Loturco and Fabio Y. Nakamura

Purpose:

To compare the LnRMSSD and the LnRMSSD:RR values obtained during a 5-min stabilization period with the subsequent 5-min criterion period and to determine the time course for LnRMSSD and LnRMSSD:RR stabilization at 1-min analysis in elite team-sport athletes.

Participants:

35 elite futsal players (23.9 ± 4.5 y, 174.2 ± 4.0 cm, 74.0 ± 7.5 kg, 1576.2 ± 396.3 m in the Yo-Yo test level 1).

Methods:

The RR-interval recordings were obtained using a portable heart-rate monitor continuously for 10 min in the seated position. The 2 dependent variables analyzed were LnRMSSD and LnRMSSD:RR. To calculate the magnitude of the differences between time periods, effect-size (ES) analysis was conducted. To assess the levels of agreement, intraclass correlation coefficients (ICC) and Bland-Altman plots were used.

Results:

The LnRMSSD and LnRMSSD:RR values obtained during the stabilization period (0–5 min) presented very large to nearly perfect ICCs with the values obtained during the criterion period (5–10 min), with trivial ESs. In the ultra-short-term analysis (ie, 1-min segments) the data showed slightly less accurate results, but only trivial to small differences with very large to nearly perfect ICCs were found.

Conclusion:

LnRMSSD and LnRMSSD:RR can be recorded in 5 min without traditional stabilization periods under resting conditions in team-sport athletes. The ultra-short-term analysis (1 min) also revealed acceptable levels of agreement with the criterion.

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Selenia di Fronso, Fabio Y. Nakamura, Laura Bortoli, Claudio Robazza and Maurizio Bertollo

The aim of the study was to examine differences in stress and recovery across gender and time (preseason and play-offs) in a sample of amateur basketball players of the Italian league (C division). Fifty amateur basketball players (33 men and 17 women) age 17–30 y (23.5 ± 9.19 y) participated in the study. Twenty-eight athletes (16 men and 12 women) completed the Recovery-Stress Questionnaire for Sport (RESTQ-Sport) in the preseason phase, after a training period of 21 days, and in the competition phase during the play-off period. Repeated-measures MANOVA showed significant differences by gender and preparation phase. Univariate follow-up ANOVA highlighted differences by gender on physical recovery, sleep quality, and self-efficacy, with higher scores in men. Moreover, differences between preseason and competition phases were shown on emotional stress and fatigue, with higher scores on emotional stress and lower scores on fatigue in the competition phase. These findings suggest that RESTQ-Sport could be a useful tool for coaches to monitor stress/recovery balance in male and female team-sport athletes during different periods of the season.

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Júlio A. Costa, João Brito, Fábio Y. Nakamura, Eduardo M. Oliveira and António N. Rebelo

Purpose: To assess the sensitivity of nocturnal heart-rate-variability-monitoring methods to the effects of late-night soccer training sessions in female athletes. Methods: Eleven female soccer players competing in the first division of the Portuguese soccer league wore heart-rate monitors during sleep at night throughout a 1-wk competitive in-season microcycle, after late-night training sessions (n = 3) and rest days (n = 3). Heart rate variability was analyzed through “slow-wave sleep episode” (10-min duration) and “hour by hour” (all the RR intervals recorded throughout the hours of sleep). Training load was quantified by session rating of perceived exertion (281.8 [117.9] to 369.0 [111.7] arbitrary units [a.u.]) and training impulse (77.5 [36.5] to 110.8 [31.6] a.u.), added to subjective well-being ratings (Hopper index = 11.6 [4.4] to 12.8 [3.2] a.u.). These variables were compared between training and rest days using repeated-measures analysis of variance. Results: The log-transformed slow-wave sleep-episode cardiac autonomic activity (lnRMSSD [natural logarithm of the square root of the mean of the sum of the squares of differences between adjacent normal RR intervals] varying between 3.92 [0.57] and 4.20 [0.60] ms; ηp2=.16; 95% confidence interval, .01–.26), lnHF (natural logarithm of high frequency), lnLF (natural logarithm of low frequency), lnSD1 (natural logarithm of short-term beat-to-beat variability), and lnSD2 (natural logarithm of long-term beat-to-beat variability), and the nontransformed LF/HF were not different among night-training session days and rest days (P > .05). Considering the hour-by-hour method (lnRMSSD varying between 4.05 [0.35] and 4.33 [0.32] ms; ηp2=.46; 95% confidence interval, .26–.52), lnHF, lnLF, lnSD1, and lnSD2 and the nontransformed LF/HF were not different among night-training session days and rest days (P > .05). Conclusion: Late-night soccer training does not seem to affect nocturnal slow-wave sleep-episode and hour-by-hour heart-rate-variability indices in highly trained athletes.

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Daniel A. Boullosa, Laurinda Abreu, Fábio Y. Nakamura, Víctor E. Muñoz, Eduardo Domínguez and Anthony S. Leicht

Purpose:

The purpose of this study was to evaluate changes in autonomic control of heart rate (HR) and fitness in a group of elite soccer players during the preseason.

Methods:

Eight professional male soccer players competing in the Spanish First Division were evaluated in July (wk 1) and September (wk 8) with night-time HR variability (HRV) over 4 different days, ultra-short-term HR recovery (HRR) during a small-sided-games session, Yo-Yo Intermittent Recovery test level 1 (Yo-Yo IR1), and a field test for determination of maximum aerobic speed.

Results:

Players exhibited a greater HRV and a faster ultra-short-term HRR at wk 8, with the players with a lower HRV at wk 1 exhibiting the greatest improvements at wk 8. However, there were unclear improvements in performance parameters, with maximum HR (HRmax) being reduced over the preseason period. This change in HRmax was correlated with the change in short-term HRV parameters (ρ = 0.829, P = .042). Large correlations were observed among HRV, ultra-short-term HRR, and field performance parameters only at wk 8. Furthermore, the variation (%) of the root-mean-square of successive differences between R-R intervals was increased during the preseason (12.95% ± 15.14% to 29.39% ± 21.93%, P = .013) and significantly correlated (r = .898, P = .006) with Yo-Yo IR1 performance (~2600 ± 786 m) at wk 8.

Conclusions:

The current results support the appropriateness and practicality of night-time HRV and ultra-short-term HRR for evaluation of autonomic adaptations in professional soccer players, despite the unclear improvements in specific field performance parameters.

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Renato Barroso, Diego F. Salgueiro, Everton C. do Carmo and Fábio Y. Nakamura

Purpose:

To assess swimmers’ session rating of perceived exertion (sRPE) after standardized sets of interval swimming training performed at the same relative intensity but with different total volume and repetition distance.

Methods:

Thirteen moderately trained swimmers (21.1 ± 1.1 y, 178 ± 6 cm, 74.1 ± 8.3 kg, 100-m freestyle 60.2 ± 2.9 s) performed 4 standardized sets (10 × 100-m, 20 × 100-m, 10 × 200-m, and 5 × 400-m) at the same relative intensity (ie, critical speed), and 1 coach (age 31 y, 7 y coaching experience) rated their efforts. Swimmers’ sRPE was assessed 30 min after the training session. Coach sRPE was collected before each training session. Internal load was calculated by multiplying sRPE by session duration.

Results:

When bouts with the same repetition distance and different volumes (10 × 100-m vs 20 × 100-m) are compared, sRPE and internal load are higher in 20 × 100-m bouts. When maintaining constant volume, sRPE and internal load (20 × 100-m, 10 × 200-m, and 5 × 400-m) are higher only in 5 × 400-m bouts. The coach’s and swimmers’ sRPE differed in 10 × 200-m and 5 × 400-m.

Conclusions:

These results indicate that sRPE in swimming is affected not only by intensity but also by volume and repetition distance. In addition, swimmers’ and the coach’s sRPE were different when longer repetition distances were used during training sessions. Therefore, care should be taken when prescribing swimming sessions with longer volume and/or longer repetition distances.

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Júlio A. Costa, João Brito, Fábio Y. Nakamura, Eduardo M. Oliveira, Ovidio P. Costa and António N. Rebelo

Purpose: To analyze whether exercise training conducted at night disturbs sleep and affects nocturnal cardiac autonomic control in high-level female athletes. Methods: A total of 18 high-level female soccer players (mean [SD] age 20.4 [2.1] y) wore actigraphs and heart-rate (HR) monitors during night sleep throughout night training days (n = 8) and resting days (n = 8), for 3 consecutive weeks. This was a longitudinal study that measured internal training load, sleep, nocturnal cardiac autonomic activity, and well-being ratings prior to training sessions. Results: Training load varied across training days (eg, training impulse range, mean [SD]; effect size, ES [95% confidence interval]: 72.9 [18.8] to 138.4 [29.6] a.u.; F 4,62 = 32.331; ηp2=.673 [.001–.16], large effect; P < .001). However, no differences in subjective well-being ratings were observed, although ES was large. Total sleep time (training days vs resting days: 07:17 [00:47] h vs 07:51 [00:42] h; ES = 0.742 [0.59–0.92], P = .005; moderate effect) and sleep-onset time (00:58 [00:19] h vs 00:44 [00:16] h; ES = 0.802 [0.68–0.94], P = .001; moderate effect) were negatively affected after night training. In addition, small effects were detected for wake-up time, time in bed, and sleep latency (P > .05). No differences were detected in HR variability during sleep (range of lnRMSSD: 4.3 [0.4] to 4.5 [0.4] ln[ms] vs 4.6 [0.3] to 4.5 [0.4] ln[ms]; F 3,52 = 2.148; P > .05; ηp2=.112 [.01–.25], medium effect), but HR during sleep was significantly higher after training days (range of HR: 56 [4] to 63 [7] beats/min vs 54 [4] to 57 [6] beats/min; F 2,32 = 15.956; P < .001; ηp2=.484 [.20–.63], large effect). Conclusion: Overall, the results indicate that exercise training conducted at night may disturb sleep and affect HR, whereas limited effects can be expected in HR variability assessed during sleep in high-level female soccer players.

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Lucas Pereira, Ciro Winckler, Cesar C. Cal Abad, Ronaldo Kobal, Katia Kitamura, Amaury Veríssimo, Fabio Y. Nakamura and Irineu Loturco

This study compared the physical performance of Paralympic sprinters with visual impairments (PSVI) and their guides in jump and sprint tests. Ten PSVI and guides executed squat jumps (SJ), countermovement jumps (CMJ), horizontal quintuple right/left-leg jumps (QR/QL), decuple jumps (DEC), and 50-m-sprint tests. The guides were superior to the PSVI in SJ (35.9 ± 6.3 vs 45.6 ± 3.2 cm), CMJ (38.5 ± 6.2 vs 46.7 ± 4.0 cm), QR (9.2 ± 1.9 vs 12.7 ± 1.0 m), QL (9.4 ± 1.9 vs 13.1 ± 0.8 m), DEC (21.0 ± 3.3 vs. 27.2 ± 1.7 m), and 50-m sprints (8.4 ± 0.4 vs 7.6 ± 0.5 m/s). The average differences between the PSVI and guides in the sprint tests was 10%, range 1–24%. Therefore, substantial differences in sprinting speed (in favor of the guides) between the peers were observed. Coaches should develop strategies to train the guides to improve their muscle-power performance.

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Irineu Loturco, Lucas A. Pereira, Cesar C. Cal Abad, Saulo Gil, Katia Kitamura, Ronaldo Kobal and Fábio Y. Nakamura

Purpose:

To determine whether athletes from different sport disciplines present similar mean propulsive velocity (MPV) in the half-squat (HS) during submaximal and maximal tests, enabling prediction of 1-repetition maximum (1-RM) from MPV at any given submaximal load.

Methods:

Sixty-four male athletes, comprising American football, rugby, and soccer players; sprinters and jumpers; and combat-sport strikers attended 2 testing sessions separated by 2–4 wk. On the first visit, a standardized 1-RM test was performed. On the second, athletes performed HSs on Smith-machine equipment, using relative percentages of 1-RM to determine the respective MPV of submaximal and maximal loads. Linear regression established the relationship between MPV and percentage of 1-RM.

Results:

A very strong linear relationship (R2 ≈ .96) was observed between the MPV and the percentages of HS 1-RM, resulting in the following equation: %HS 1-RM = −105.05 × MPV + 131.75. The MPV at HS 1-RM was ~0.3 m/s.

Conclusion:

This equation can be used to predict HS 1-RM on a Smith machine with a high degree of accuracy.

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Vinícius F. Milanez, Rafael E. Pedro, Alexandre Moreira, Daniel A. Boullosa, Fuad Salle-Neto and Fábio Y. Nakamura

Purpose:

The aim of this study was to verify the influence of aerobic fitness (VO2max) on internal training loads, as measured by the session rating of perceived exertion (session-RPE) method.

Methods:

Nine male professional outfeld futsal players were monitored for 4 wk of the in-season period with regards to the weekly accumulated session-RPE, while participating in the same training sessions. Single-session-RPE was obtained from the product of a 10-point RPE scale and the duration of exercise. Maximal oxygen consumption was determined during an incremental treadmill test.

Results:

The average training load throughout the 4 wk period varied between 2,876 and 5,035 arbitrary units. Technical-tactical sessions were the predominant source of loading. There was a significant correlation between VO2max (59.6 ± 2.5 mL·kg–1 ·min–1) and overall training load accumulated over the total period (r = –0.75).

Conclusions:

The VO2max plays a key role in determining the magnitude of an individual’s perceived exertion during futsal training sessions.