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Assessing Shortened Field-Based Heart-Rate-Variability-Data Acquisition in Team-Sport Athletes

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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Cardiac Autonomic and Neuromuscular Responses During a Karate Training Camp Before the 2015 Pan American Games: A Case Study With the Brazilian National Team

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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Differences in Strength, Speed, and Power Performance Between Visually Impaired Paralympic and Olympic Sprinters

Tomás T. Freitas, Pedro E. Alcaraz, Ciro Winckler, Santiago Zabaloy, Lucas A. Pereira, and Irineu Loturco

Purpose: To compare the strength, speed, and power performance of elite sprinters with and without visual impairment. Methods: Twelve elite able-bodied sprinters and 15 Paralympic sprinters with visual impairment took part in this study. Sprinters from both groups performed the following tests: squat and countermovement jumps, maximum bar-power output in the half-squat and jump-squat exercises, and 60-m sprint. The differences between groups in all variables examined were analyzed using the independent t test. Results: Olympic sprinters revealed better performances in all tests when compared with Paralympic sprinters with visual impairment (effect sizes ranging from 1.29 to 9.04; P < .001). Differences of ∼32% and ∼20% were found for the half-squat and loaded and unloaded vertical jumps, respectively. Smaller differences (from ∼8% to ∼11%) were obtained in linear sprint performance. Conclusions: Between-groups differences peaked at low-velocity exercises (eg, ∼32% in the half-squat) and decreased as movement velocity and specificity increased (eg, ∼8% at 60-m sprint). Thus, the greatest differences between Olympic and Paralympic sprinters seem to be related to their ability to apply force at low movement velocities. Coaches are encouraged to work on all sprinting phases and across the entire force–velocity spectrum, bearing in mind that improvements in strength capacity will possibly lead to increased sprint performance in Paralympic sprinters with visual impairment, especially in the acceleration phase of sprinting.

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Load–Velocity Relationship in National Paralympic Powerlifters: A Case Study

Irineu Loturco, Lucas A. Pereira, Ciro Winckler, Weverton L. Santos, Ronaldo Kobal, and Michael McGuigan

Purpose: To examine the relationships between different loading intensities and movement velocities in the bench-press exercise (BP) in Paralympic powerlifters. Methods: A total of 17 national Paralympic powerlifters performed maximum dynamic strength tests to determine their BP 1-repetition maximum (1RM) in a Smith-machine device. A linear position transducer was used to measure movement velocity over a comprehensive range of loads. Linear-regression analysis was performed to establish the relationships between the different bar velocities and the distinct percentages of 1RM. Results: Overall, the correlations between bar velocities and %1RM were strong over the entire range of loads (R 2 .80–.91), but the precision of the predictive equations (expressed as mean differences [%] between actual and predicted 1RM values) were higher at heavier loading intensities (∼20% for loads ≤70% 1RM and ∼5% for loads ≥70% 1RM). In addition, it seems that these very strong athletes (eg, 1RM relative in the BP = 2.22 [0.36] kg·kg−1, for male participants) perform BP 1RM assessments at lower velocities than those previously reported in the literature. Conclusions: The load–velocity relationship was strong and consistent in Paralympic powerlifters, especially at higher loads (≥70% 1RM). Therefore, Paralympic coaches can use the predictive equations and the reference values provided here to determine and monitor the BP loading intensity in national Paralympic powerlifters.

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One-Repetition-Maximum Measures or Maximum Bar-Power Output: Which Is More Related to Sport Performance?

Irineu Loturco, Timothy Suchomel, Chris Bishop, Ronaldo Kobal, Lucas A. Pereira, and Michael McGuigan

Purpose: To compare the associations between optimum power loads and 1-repetition-maximum (1RM) values (assessed in half-squat and jump-squat exercises) and multiple performance measures in elite athletes. Methods: Sixty-one elite athletes (15 Olympians) from 4 different sports (track and field [sprinters and jumpers], rugby sevens, bobsled, and soccer) performed squat and countermovement jumps, half-squat exercise (to assess 1RM), half-squat and jump-squat exercises (to assess bar-power output), and sprint tests (60 m for sprinters and jumpers and 40 m for the other athletes). Pearson product–moment correlation test was used to determine relationships between 1RM and bar-power outputs with vertical jumps and sprint times in both exercises. Results: Overall, both measurements were moderately to near perfectly related to speed performance (r values varying from −.35 to −.69 for correlations between 1RM and sprint times, and from −.36 to −.91 for correlations between bar-power outputs and sprint times; P < .05). However, on average, the magnitude of these correlations was stronger for power-related variables, and only the bar-power outputs were significantly related to vertical jump height. Conclusions: The bar-power outputs were more strongly associated with sprint-speed and power performance than the 1RM measures. Therefore, coaches and researchers can use the bar-power approach for athlete testing and monitoring. Due to the strong correlations presented, it is possible to infer that meaningful variations in bar-power production may also represent substantial changes in actual sport performance.

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Determining the Optimum Bar Velocity in the Barbell Hip Thrust Exercise

Irineu Loturco, Timothy Suchomel, Chris Bishop, Ronaldo Kobal, Lucas A. Pereira, and Michael R. McGuigan

Purpose: To identify the bar velocities that optimize power output in the barbell hip thrust exercise. Methods: A total of 40 athletes from 2 sports disciplines (30 track-and-field sprinters and jumpers and 10 rugby union players) participated in this study. Maximum bar-power outputs and their respective bar velocities were assessed in the barbell hip thrust exercise. Athletes were divided, using a median split analysis, into 2 groups according to their bar-power outputs in the barbell hip thrust exercise (“higher” and “lower” power groups). The magnitude-based inferences method was used to analyze the differences between groups in the power and velocity outcomes. To assess the precision of the bar velocities for determining the maximum power values, the coefficient of variation (CV%) was also calculated. Results: Athletes achieved the maximum power outputs at a mean velocity, mean propulsive velocity, and peak velocity of 0.92 (0.04) m·s−1 (CV: 4.1%), 1.02 (0.05) m·s−1 (CV: 4.4%), and 1.72 (0.14) m·s−1 (CV: 8.4%), respectively. No meaningful differences were observed in the optimum bar velocities between higher and lower power groups. Conclusions: Independent of the athletes’ power output and bar-velocity variable, the optimum power loads frequently occur at very close bar velocities.

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Sensitivity of the Yo-Yo Intermittent Recovery Test and Cardiac Autonomic Responses to Training in Futsal Players

Victor H. de Freitas, Lucas A. Pereira, Eberton A. de Souza, Anthony S. Leicht, Maurizio Bertollo, and Fábio Y. Nakamura

Purpose:

This study examined the sensitivity of maximal (Yo-Yo Intermittent Recovery [IR] 1 and 2) and submaximal (5’-5’) tests to identify training adaptations in futsal players along with the suitability of heart-rate (HR) and HR-variability (HRV) measures to identify these adaptations.

Methods:

Eleven male professional futsal players were assessed before (pretraining) and after (posttraining) a 5-wk period. Assessments included 5’-5’ and Yo-Yo IR1 and IR2 performances and HR and HRV at rest and during the IR and 5’-5’ tests. Magnitude-based-inference analyses examined the differences between pre- and posttraining, while relationships between changes in variables were determined via correlation.

Results:

Posttraining, Yo-Yo IR1 performance likely increased while Yo-Yo IR2 performance almost certainly increased. Submaximal HR during the Yo-Yo IR1 and Yo-Yo IR2 almost certainly and likely, respectively, decreased with training. HR during the 5’-5’ was very likely decreased, while HRV at rest and during the 5’-5’ was likely increased after training. Changes in both Yo-Yo IR performances were negatively correlated with changes in HR during the Yo-Yo IR1 test and positively correlated with the change in HRV during the 5’-5’.

Conclusions:

The current study has identified the Yo-Yo IR2 as more responsive for monitoring training-induced changes of futsal players than the Yo-Yo IR1. Changes in submaximal HR during the Yo-Yo IR and HRV during the 5’-5’ were highly sensitive to changes in maximal performance and are recommended for monitoring training. The 5’-5’ was recommended as a time-efficient method to assess training adaptations for futsal players.

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Effects of Plyometric Training on Physical Performance of Young Male Soccer Players: Potential Effects of Different Drop Jump Heights

Rodrigo Ramirez-Campillo, Cristian Alvarez, Felipe García-Pinillos, Paulo Gentil, Jason Moran, Lucas A. Pereira, and Irineu Loturco

Purpose: To compare the effects of plyometric drop jump (DJ) training against those induced by regular soccer training and assess the transference effect coefficient (TEC) of DJs (“trained exercises”) performed from 20- (DJ20) and 40-cm (DJ40) height boxes with respect to different physical qualities (jumping, linear and change of direction speed, kicking, endurance, and maximal strength) in youth male soccer players. Methods: Participants were randomly divided into a control group (n = 20; age: 13.5 [1.9] y) and a DJ training group (n = 19; age: 13.2 [1.8] y), and trained for 7 weeks. A 2-way analysis of variance for repeated measures with the within-subject factor time (preintervention and postintervention) and between-subject factor group (intervention vs control) was performed. To calculate the TECs between the trained exercises (DJ20 and DJ40) and the physical tests, the ratio between the “result gains” (effect size [ES]) in the analyzed physical qualities and the result gains in the trained exercises were calculated. The TECs were only calculated for variables presenting an ES ≥ 0.2. Results: Significant improvements (ES = 0.21–0.46; P < .05) were observed in the DJ training group, except in linear sprint performance. The control group improved only the maximal strength (ES = 0.28; P < .05). Significant differences were observed in all variables (ES = 0.20–0.55; P < .05) in favor of the DJ training group, except for maximal strength (group × time interaction). Conclusions: A plyometric training scheme based on DJs was able to significantly improve the physical performance of youth male soccer players. Overall, greater TECs were observed for DJ40 (0.58–1.28) than DJ20 (0.55–1.21).

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Effects of a Congested Fixture Period on Speed and Power Performance of Elite Young Soccer Players

Tomás T. Freitas, Lucas A. Pereira, Valter P. Reis, Victor Fernandes, Pedro E. Alcaraz, Paulo H.S.M. Azevedo, and Irineu Loturco

Purpose: To investigate the effects of a match-congested period on straight and curve sprint performance, change of direction (COD) speed and deficit, vertical jumping ability, and half-squat (HS) mean propulsive power (MPP) output in young soccer players. Methods: A total of 15 under-20 elite male soccer players participated in 14 matches over 8 weeks. The following assessments were performed before and after the congested fixture period: squat and countermovement jumps, 17-m linear sprint, curve sprint test for the “good” (CSGS) and “weak” (CSWS) sides, modified 17-m Zigzag test, and HS MPP. Magnitude-based inferences and a paired t test were used to analyze pre–post changes in the assessed variables. Results: Very likely (P < .05) decreases were noticed in 17-m sprint velocity (effect size [ES] [90% confidence limit; CL], −0.56 [−0.32 to −0.81]) and CSGS (ES [90% CL], −0.72 [−0.40 to 1.03]) after the 8-week period. A possible but nonsignificant impairment was revealed in CSWS (ES [90% CL], −0.18 [0.03 to −0.39]), and countermovement jump (ES [90% CL], −0.21 [−0.54 to 0.12]). Zigzag velocity (ES [90% CL], −2.90 [−2.45 to −3.36]) and COD deficit (ES [90% CL], 0.86 [0.52 to 1.20]) were almost certainly and significantly (P < .05) reduced and increased, respectively, after the match-congested period. An almost certain and significant (P < .05) reduction was found in HS MPP (ES [90% CL], −1.18 [−0.76 to −1.61]). Conclusions: Straight and curve sprint velocity, COD speed and deficit, and HS MPP were impaired after the match-congested period. Vertical jump height was possibly decreased. Seasonal phases comprising high volumes of soccer-specific training and competition seem to be detrimental to speed–power qualities in under-20 elite soccer players.

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Maximum Strength, Relative Strength, and Strength Deficit: Relationships With Performance and Differences Between Elite Sprinters and Professional Rugby Union Players

Irineu Loturco, Lucas A. Pereira, Tomás T. Freitas, Chris Bishop, Fernando Pareja-Blanco, and Michael R. McGuigan

Purpose: To test the relationships between maximum and relative strength (MS and RS), absolute and relative peak force (PF and RPF), and strength deficit (SDef), with sprint and jump performance, and to compare these mechanical variables between elite sprinters and professional rugby union players. Methods: Thirty-five male rugby union players and 30 male sprinters performed vertical jumps, 30-m sprint, and half-squat 1-repetition maximum (1RM), where these force-related parameters were collected. Pearson correlation coefficients were used to test the relationships between the variables. An independent t test and magnitude-based inferences compared the mechanical variables between sprinters and rugby players. Results: Almost certain significant differences were observed for jump and sprint performance between groups (P < .0001). The rugby union players demonstrated a likely significant higher MS (P = .03) but a very likely lower RS (P = .007) than the sprinters. No significant differences were observed for PF between them. The sprinters exhibited an almost certain significant higher RPF than the rugby players (P < .0001). Furthermore, the rugby players demonstrated almost certain to likely significant higher SDef from 40% to 70% 1RM (P < .05) compared with the sprinters. Overall, all strength-derived parameters were significantly related to functional performance. Conclusions: Elite sprinters present higher levels of RS and RPF, lower levels of SDef, and better sprint and jump performance than professional rugby players. Relative strength-derived values (RS and RPF) and SDef are significantly associated with speed–power measures and may be used as effective and practical indicators of athletic performance.