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Change-of-Direction and Deceleration Deficits in National-Team Female Rugby Sevens Players: Interrelationships and Associations With Speed-Related Performance

Tomás T. Freitas, Lucas A. Pereira, Santiago Zabaloy, Pedro E. Alcaraz, Ademir F.S. Arruda, Valter P. Mercer, Chris Bishop, and Irineu Loturco

Purpose: To investigate the relationships between a series of direct and indirect measures of linear and multidirectional speed performance in elite female rugby sevens players. Methods: Nineteen players from the Brazilian national team performed 40-m linear sprint and 505 change-of-direction (COD) tests on the same day. Based on the linear sprint and COD test performances, the COD deficit (CODD) and deceleration deficit (DD) were also obtained. A Pearson product–moment correlation analysis was used to determine the relationships between linear sprint and COD-derived variables. Results: Linear sprint and 505 COD velocities were not significantly associated (P > .05). Large to very large significant associations (r values ranging from .54 to .78; P < .05) were detected between linear sprint velocity for the different distances tested (10, 15, 30, and 40 m) and CODD. The COD velocity presented a very large inverse significant correlation with CODD and DD (r = −.77 and −.79 respectively; P < .05). A large and significant correlation was identified between CODD and DD (r = .79; P < .05). Conclusions: Significant associations were observed between linear sprint and CODD, suggesting that faster players are less efficient at changing direction. No relationship was found between sprint velocity and DD, highlighting the independent nature of linear sprints and deceleration capabilities. A comprehensive and detailed analysis of multidirectional speed performance should consider not only linear sprint and COD performances but also complementary COD-derived variables such as the CODD and DD.

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Competitive Cross-Country Skiers Have Longer Time to Exhaustion Than Recreational Cross-Country Skiers During Intermittent Work Intervals Normalized to Their Maximal Aerobic Power

Eivind Holsbrekken, Øyvind Gløersen, Magne Lund-Hansen, and Thomas Losnegard

Purpose: To investigate differences in time to exhaustion (TTE), O2 uptake ( V ˙ O 2 ), and accumulated O2 deficit ( O 2 def ) between competitive and recreational cross-country (XC) skiers during an intermittent-interval protocol standardized for maximal aerobic power (MAP). Methods: Twelve competitive (maximal V ˙ O 2 [ V ˙ O 2 max ] = 76.5 ± 3.8 mL · kg 1 · min 1 ) and 10 recreational ( V ˙ O 2 max = 63.5 ± 6.3 mL · kg 1 · min 1 ) male XC skiers participated. All tests were performed on a rollerski treadmill in the V2 ski-skating technique. To quantify MAP and maximal accumulated oxygen deficit (MAOD), the skiers performed a steady-state submaximal test followed by a 1000-m time trial. After a 60-minute break, TTE, V ˙ O 2 , and accumulated O 2 def were measured during an intermittent-interval protocol (40-s work and 20-s recovery), which was individually tailored to 120% and 60% of each subject’s MAP. Results: During the 1000-m time trial, the competitive skiers had 21% (95% CI, 12%–30%) shorter finish time and 24% (95% CI, 14%–34%) higher MAP (all P < .01) than the recreational skiers. No difference was observed in relative exercise intensity (average power/MAP; P = .28), MAOD (P = .18), or fractional utilization of V ˙ O 2 max . During the intermittent-interval protocol, the competitive skiers had 34% (95% CI, 3%–65%) longer TTE (P = .03) and accumulated 61% (95% CI, 27%–95%) more O 2 def (P = .001) than the recreational skiers during work phases. Conclusions: Competitive XC skiers have longer TTE and accumulate more O 2 def than recreational XC skiers during an intermittent-interval protocol at similar intensity relative to MAP. This implies that performance in intermittent endurance sports is related to the ability to repeatedly recharge fractions of MAOD.

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A Systematic Review on the Physical, Physiological, Perceptual, and Technical–Tactical Demands of Official 3 × 3 Basketball Games

Pierpaolo Sansone, Daniele Conte, Antonio Tessitore, Ermanno Rampinini, and Davide Ferioli

Purpose: To systematically review the physical, physiological, perceptual, and technical–tactical demands of official 3 × 3 basketball games. Methods: The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed. Three electronic databases (PubMed, Scopus, and Web of Science) were systematically searched to identify studies assessing physical, physiological, perceptual, and technical–tactical demands of 3 × 3 games. Data were also coded according to player sex and tournament phase. Quality assessment of the included studies was performed using a modified Downs and Black checklist. Results: Thirteen articles were finally included, with a mean quality of 8.6 (1.1) out of 11. Three-by-three basketball games have an intermittent profile (1:1 work–rest ratio), with a duration of ∼15 minutes, and are characterized by short (6–8 s) ball possessions and considerable physical (17–33 accelerations, 24–44 decelerations, 62–94 changes of directions, and 17–24 jumps per game) and physiological (lactate: ∼6.2 mmol·L−1) demands. Overall, the game performance profile is similar in males and females, with minor changes happening across tournament phases. Several key technical–tactical indicators were identified as discriminating winning and losing teams, such as better shooting and defensive efficiency, low number of turnovers, and implementing tactical actions involving more players, passing first, and ending possessions with shots from outside of the arch from the top of the key. Conclusions: Three-by-three basketball is an intermittent, physically demanding sport characterized by quick plays and specific tactical constraints. This review provides information that should be considered by performance staff to improve training prescription, game tactical plans, and for player selection and talent identification.

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Enhancing the Initial Acceleration Performance of Elite Rugby Backs. Part II: Insights From Multiple Longitudinal Individual-Specific Case-Study Interventions

James J. Wild, Ian N. Bezodis, Jamie S. North, and Neil E. Bezodis

Purpose: This study implemented 18-week individual-specific sprint acceleration training interventions in elite male rugby backs based on their predetermined individual technical needs and evaluated the effectiveness of these interventions. Methods: Individual-specific interventions were prescribed to 5 elite rugby backs over an 18-week period. Interventions were informed by the relationships between individual technique strategies and initial acceleration performance, and their strength-based capabilities. Individual-specific changes in technique and initial acceleration performance were measured at multiple time points across the intervention period and compared with 3 control participants who underwent their normal training. Results: Of the technique variables intentionally targeted during the intervention period, moderate to very large (|d| = 0.93–3.99) meaningful changes were observed in the participants who received an individual-specific intervention but not in control participants. Resultant changes to the intervention participants’ whole-body kinematic strategies were broadly consistent with the intended changes. Moderate to very large (|d| = 1.11–2.82) improvements in initial acceleration performance were observed in participants receiving individual-specific technical interventions but not in the control participants or the participant who received an individual-specific strength intervention. Conclusions: Individual-specific technical interventions were more effective in manipulating aspects of acceleration technique and performance compared with the traditional “one-size-fits-all” approach adopted by the control participants. This study provides a novel, evidence-based approach for applied practitioners working to individualize sprint-based practices to enhance acceleration performance.

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In-Season Resisted-Jump Training Enables Power, Agility, and Jump-Ability Maintenance in University-Level Male Rugby Players

Cobus Oosthuizen and Mark Kramer

Purpose: To determine the effects and transferability of a resisted-jump training program on strength, speed, power, and agility maintenance during the in-season phase of rugby training. Methods: Thirty high-level male rugby players (age: 21.78 [1.86] y; height: 1.83 [0.10] m; mass: 95.17 [10.45] kg) participated in a crossover, within-subject study design. Participants were randomly assigned to treatment groups (resistance band [VertiMax, VM] or control [Con]) and evaluated on jumping, sprinting, agility, and strength over a 4-week period. A 10-week wash-out period was initiated, followed by a crossover that incorporated randomization of the treatment sequence (ie, receiving VM during the first or second phase of the testing period). Within- and between-groups differences for each variable of interest were evaluated using a linear mixed-effects model. Results: No significant treatment (VM vs Con) or time (pre vs postintervention) effects were evident across all variables (all P > .197), although the order or treatment allocation may play a role for strength (P = .037) and jumping (P = .003). Power, agility, and countermovement-jump height were statistically equivalent for the intervention period. Following the VM treatment, changes in strength seem to transfer favorably to changes in agility (r = −.54, P < .05) but no other variables, and no significant associations were evident for the Con treatment. Conclusion: Regardless of treatment, power, agility, and jump height were conserved throughout the treatment period. Although changes in mean sprint and strength were not significantly different from zero, it was not possible to conclude whether performance decrements could be eliminated.

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Hematological Adaptations Following a Training Camp in Hot and/or Hypoxic Conditions in Elite Rugby Union Players

Julien D. Périard, Olivier Girard, Nathan Townsend, Pitre Bourdon, Scott Cocking, Mohammed Ihsan, Mathieu Lacome, David Nichols, Gavin Travers, Mathew G. Wilson, Julien Piscione, and Sebastien Racinais

Purpose: To investigate the effects of a training camp with heat and/or hypoxia sessions on hematological and thermoregulatory adaptations. Methods: Fifty-six elite male rugby players completed a 2-week training camp with 5 endurance and 5 repeated-sprint sessions, rugby practice, and resistance training. Players were separated into 4 groups: CAMP trained in temperate conditions at sea level, HEAT performed the endurance sessions in the heat, ALTI slept and performed the repeated sprints at altitude, and H + A was a combination of the heat and altitude groups. Results: Blood volume across all groups increased by 140 mL (95%CI, 42–237; P = .006) and plasma volume by 97 mL (95%CI 28–167; P = .007) following the training camp. Plasma volume was 6.3% (0.3% to 12.4%) higher in HEAT than ALTI (P = .034) and slightly higher in HEAT than H + A (5.6% [−0.3% to 11.7%]; P = .076). Changes in hemoglobin mass were not significant (P = .176), despite a ∼1.2% increase in ALTI and H + A and a ∼0.7% decrease in CAMP and HEAT. Peak rectal temperature was lower during a postcamp heat-response test in HEAT (0.3 °C [0.1–0.5]; P = .010) and H + A (0.3 °C [0.1–0.6]; P = .005). Oxygen saturation upon waking was lower in ALTI (3% [2% to 5%]; P < .001) and H + A (4% [3% to 6%]; P < .001) than CAMP and HEAT. Conclusion: Although blood and plasma volume increased following the camp, sleeping at altitude impeded the increase when training in the heat and only marginally increased hemoglobin mass. Heat training induced adaptations commensurate with partial heat acclimation; however, combining heat training and altitude training and confinement during a training camp did not confer concomitant hematological adaptations.

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The 2-Point Method: Theoretical Basis, Methodological Considerations, Experimental Support, and Its Application Under Field Conditions

Amador García-Ramos

The “2-point method,” originally referred to as the “2-load method,” was proposed in 2016 by Prof Slobodan Jaric to characterize the maximal mechanical capacities of the muscles to produce force, velocity, and power. Two years later, in 2018, Prof Jaric and I summarized in a review article the scientific evidence showing that the 2-point method, compared with the multiple-point method, is capable of providing the outcomes of the force–velocity (F–V) and load–velocity (L–V) relationships with similar reliability and high concurrent validity. However, a major gap of our review was that, until 2018, the feasibility of the 2-point method had only been explored through testing procedures based on multiple (more than 2) loads. This is problematic because (1) it has misled users into thinking that implementing the 2-point method inevitably requires testing more than 2 conditions and (2) obtaining the data from the same test could have artificially inflated the concurrent validity of the 2-point method. To overcome these limitations, subsequent studies have implemented in separate sessions the 2-point method under field conditions (only 2 different loads applied in the testing protocol) and the standard multiple-point method. These studies consistently demonstrate that while the outcomes of the 2-point method exhibit comparable reliability, they tend to have slightly higher magnitudes compared with the standard multiple-point method. This review article emphasizes the practical aspects that should be considered when applying the 2-point method under field conditions to obtain the main outcomes of the F–V and L–V relationships.

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Anaerobic Speed Reserve and Performance Relationships Between International and World-Class Short-Track Speed Skating

Simon Deguire, Gareth N. Sandford, and François Bieuzen

Purpose: Short-track speed skating race distances of 500, 1000, and 1500 m that last ∼40 seconds to ∼2.5 minutes and require a maximal intensity at speeds beyond maximal oxygen uptake (VO2max). Recently, the anaerobic speed reserve (ASR) has been applied by scientists and coaches in middle-distance sports to deepen understanding of 1- to 5-minute event performance where different physiological profiles (speed, hybrid, and endurance) can have success. Methods: World-class (women, n = 2; men, n = 3) and international-level (women, n = 4; men, n = 5) short-track speed skaters completed maximal aerobic speed and maximal skating speed tests. ASR characteristics were compared between profiles and associated with on-ice performance. Results: World-class athletes raced at a lower %ASR in the 1000- (3.1%; large; almost certainly) and 1500-m (1.8%; large; possibly) events than international athletes. Men’s and women’s speed profiles operated at a higher %ASR in the 500-m than hybrid and endurance profiles, whereas in the 1500-m, endurance profiles worked at a substantially lower %ASR than hybrid and speed profiles. Women’s 500-m performance is very largely associated with maximal skating speed, while women’s maximal aerobic speed appears to be a key determining factor in the 1000- and 1500-m performance. Conclusion: World-class short-track speed skaters can be developed in speed, hybrid, and endurance profiles but achieve their performance differently by leveraging their strongest characteristics. These results show nuanced differences between men’s and women’s 500-, 1000- and 1500-m event performance across ASR profile that unlock new insights for individualizing athlete performance in these disciplines.

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ChatGPT for Sample-Size Calculation in Sports Medicine and Exercise Sciences: A Cautionary Note

Jabeur Methnani, Imed Latiri, Ismail Dergaa, Karim Chamari, and Helmi Ben Saad

Purpose: To investigate the accuracy of ChatGPT (Chat generative pretrained transformer), a large language model, in calculating sample size for sport-sciences and sports-medicine research studies. Methods: We conducted an analysis on 4 published papers (ie, examples 1–4) encompassing various study designs and approaches for calculating sample size in 3 sport-science and -medicine journals, including 3 randomized controlled trials and 1 survey paper. We provided ChatGPT with all necessary data such as mean, percentage SD, normal deviates (Z α/2 and Z 1−β ), and study design. Prompting from 1 example has subsequently been reused to gain insights into the reproducibility of the ChatGPT response. Results: ChatGPT correctly calculated the sample size for 1 randomized controlled trial but failed in the remaining 3 examples, including the incorrect identification of the formula in one example of a survey paper. After interaction with ChatGPT, the correct sample size was obtained for the survey paper. Intriguingly, when the prompt from Example 3 was reused, ChatGPT provided a completely different sample size than its initial response. Conclusions: While the use of artificial-intelligence tools holds great promise, it should be noted that it might lead to errors and inconsistencies in sample-size calculations even when the tool is fed with the necessary correct information. As artificial-intelligence technology continues to advance and learn from human feedback, there is hope for improvement in sample-size calculation and other research tasks. However, it is important for scientists to exercise caution in utilizing these tools. Future studies should assess more advanced/powerful versions of this tool (ie, ChatGPT4).

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Efficacy of Resisted Sled Sprint Training Compared With Unresisted Sprint Training on Acceleration and Sprint Performance in Rugby Players: An 8-Week Randomized Controlled Trial

Marco Panascì, Simone Di Gennaro, Vittoria Ferrando, Luca Filipas, Piero Ruggeri, and Emanuela Faelli

Purpose: To compare the effects between resisted sled sprint training (RSS) and unresisted sprint training (URS) on sprint and acceleration performance, vertical jump, and maximal strength during an 8-week period of preseason training. Methods: Twenty-six recreational active rugby players were randomly divided into either RSS or URS training groups and then performed 8 weeks of training, 2 sessions/wk of sprint-specific training program. The RSS group performed sprints by towing a sled overloaded with 12.6% of body mass for 2 of the 3 sets of 3 × 20-m sprints, plus one set was carried out with unresisted modality. The URS groups performed 3 sets of 3 × 20-m unresisted sprints. The measures of 10- and 30-m sprint times, vertical jump, and 3-repetition-maximum (3-RM) squat tests were performed at baseline and after 8 weeks. Results: Ten- and 30-m sprint times (P < .05 and η p 2 > .44 ) improved significantly more in RSS than in URS. Both groups improved significantly in vertical jump and 3-RM squat tests; however, no significant differences (P > .1 and η p 2 < .11 ) between groups were found. Conclusions: Our findings indicate that an 8-week program of RSS is more effective than URS for enhancing sprint time performance in male recreational active rugby players. In addition, these data suggest that a sled overload corresponding to 12.6% of body mass can induce positive effects on both acceleration and speed performance in recreational active rugby players.