Impact of a 6-Day Official Tournament on Physical Demands, Perceptual-Physiological Responses, Well-Being, and Game Performance of Under-18 Basketball Players.

PURPOSE: This study aimed to examine the effect of a 6-day basketball tournament on the physical demands, perceptual-physiological responses, well-being, and game statistics of elite under-18 (years of age) players. METHODS: Physical demands (player load [PL], steps, impacts, and jumps, all normalized by playing time), perceptual-physiological responses (heart rate and rating of perceived exertion), well-being (Hooper index), and game statistics of 12 basketball players were monitored during 6 consecutive games. Linear mixed models and Cohen d effect sizes were used to assess differences among games. RESULTS: Significant changes were found for PL per minute, steps per minute, impacts per minute, peak heart rate, and Hooper index over the tournament. Pairwise comparisons showed that PL per minute was higher in game #1 than in games #4 (P = .011, large), #5 (P < .001, very large), and #6 (P < .001, very large). PL per minute recorded during game #5 was also lower than in games #2 (P = .041, large) and #3 (P = .035, large). The number of steps per minute was higher in game #1 than in all other games (all P < .05, large to very large). Impacts per minute were significantly higher in game #3 than in games #1 (P = .035, large) and #2 (P = .004, large). The only physiological variable that varied significantly was peak heart rate (higher in game #3 than in game #6; P = .025, large). The Hooper index gradually increased throughout the tournament, indicating poorer player well-being as the tournament advanced. Game statistics did not significantly change among games. CONCLUSIONS: The average intensities of each game and the players' well-being gradually decreased throughout the tournament. Conversely, physiological responses were mostly unaffected, and game statistics were unaffected.

Training and competition injury epidemiology in professional basketball players: a prospective observational study.

BACKGROUND: There is a lack of epidemiological data comparing the characteristics of injuries sustained during basketball matches vs. training taking into account incidence, type of injury, body location and risk factors associated with the development of the injury. PURPOSE: The main aim of the present study was to analyze the incidence and characteristics of training vs. competition injuries sustained by professional basketball players. METHODS: The injuries incurred by 61 professional basketball players (mean ± SD, age: 25.7 ± 5.1 years; height: 200.2 ± 9.2 cm; body mass: 98.2 ± 13.8 kg) from the same team were prospectively recorded by the team's medical staff for 6 consecutive seasons (2014/15 to 2019/20). The team competed in a top national basketball division and in the EuroLeague among other national-level competitions. The injuries were recorded using a validated medical questionnaire that included information according to type, severity, location, and injury mechanism. Training and match times were also recorded for each player in order to calculate injury incidence. RESULTS: A total of 306 injuries were reported, representing 12.59 injuries per 1000 h of basketball play. Most injuries occurred without direct contact with another player/object (70.9%) and were located in the lower limbs (74.8%), particularly in the knee (22.9%). The incidence of injuries was higher during competition than during training: 77.83 vs. 8.29 injuries per 1000 h of basketball play. However, there were no differences in the mechanism and mode of onset between training and competition injuries while the proportion of time-loss injuries was also similar in training and competition. CONCLUSIONS: In summary, injury incidence in professional basketball was ~10-times higher during competition than during training. Beyond differences in incidence, injury characteristics were similar for basketball training and competition.

The Distribution of Match Physical Activities Relative to the Most Demanding Scenarios in Professional Basketball Players.

The purpose of this study was to examine the distribution of physical activities relative to the most demanding scenarios across playing positions during official basketball match-play. Twelve professional basketball players were monitored during twelve matches using a local positioning system. Peak physical demands were measured via total distance covered, distance covered >18 km·h-1, and the number of accelerations and decelerations >3 m·s-2 captured over 30- and 60-s rolling averages. The results showed that players were exposed to more than one high-demanding scenario in all variables and time epochs examined. Additionally, total distance covered presented the greatest number of moderate-demanding scenarios (40-80% of most demanding scenarios), whereas distance covered >18 km·h-1, and accelerations and decelerations >3 m·s-2 presented the greatest proportion of low-demanding scenarios (<40% of most demanding scenarios). Regarding positional differences, backcourt players generally experienced a higher number of scenarios than frontcourt players in most variables, especially in total distance covered. For this variable, scenarios between 20 and 70% of most demanding scenarios during the 30-s epoch (p < 0.001; ES = 0.420.78), and scenarios between 50 and 90% of most demanding scenarios during the 60-s epoch (p < 0.001; ES = 0.400.64) showed significant differences between backcourt and frontcourt players. Our data suggest that match physical activities are position-dependent and variable-dependent. In addition, peak physical demands appear to be repeated during basketball competition. These results may be considered by practitioners to complement average values and most demanding scenarios when prescribing individualized training programs to optimize team performance.

Comparison of the most demanding scenarios during different in-season training sessions and official matches in professional basketball players.

The purpose of this study was to compare physical demands during the most demanding scenarios (MDS) of different training sessions and official matches in professional basketball players across playing positions. Thirteen professional basketball players were monitored over a 9-week competitive season using a local positioning system. Peak physical demands included total distance, distance covered at > 18 km·h-1, distance and number of accelerations (≥ 2 m∙s-2) and decelerations (≤ -2 m∙s-2) over a 60-second epoch. Analysis of variance for repeated measures, Bonferroni post-hoc tests and standardised Cohen's effect size (ES) were calculated. Overall, almost all physical demands during the MDS of training were lower (-6.2% to -35.4%) compared to official matches. The only variable that surpassed competition demands was distance covered at > 18 km·h-1, which presented moderate (ES = 0.61, p = 0.01) and small (ES = 0.48, p > 0.05) increases during training sessions four and three days before a competition, respectively. Conversely, the two previous practices before match day presented trivial to very large decreases (ES = 0.09-2.66) in all physical demands. Furthermore, centres achieved the lowest peak value in total distance covered during matches, forwards completed the greatest peak distance at > 18 km·h-1, and guards performed the greatest distance and number of high-intensity accelerations and decelerations. In conclusion, physical demands during the MDS of different training sessions across the microcycle failed to match or surpass peak values during official matches, which should be considered when prescribing a training process intended to optimise the MDS of match play.

Average Game Physical Demands and the Most Demanding Scenarios of Basketball Competition in Various Age Groups.

The purpose of this study was to compare average physical demands and the most demanding 60-s scenarios of basketball match-play between five different age groups. Sixty-four male basketball players from five different age groups were monitored across eight regular-season home games. Physical demands were examined using a local positioning system and included total distance covered, distance >18 km·h-1, the number of accelerations (≥2 m·s-2) and decelerations (≤-2 m·s-2). All four game performance variables increased significantly (58.4 - 639.2%) when calculated with rolling average techniques in comparison to average physical demand values. Furthermore, the current investigation found that while Under-12 presented the highest result in relative total distance covered (p < .001; effect size = 0.58-2.01), they also showed the lowest values in the most demanding scenarios of match play and small-to-moderate effect sizes compared with their older counterparts. Both average physical demands and the most demanding scenarios presented an increasing tendency with age when distance >18 km·h-1 in basketball players was assessed. More specifically, the Under-12 age group achieved the lowest values and showed significant differences with the other four teams in both game analysis techniques (p < .001; effect size = 0.53 - 1.32). In conclusion, average game demands are shown to remarkably underestimate the most demanding scenarios of basketball match-play, and there are multiple significant differences between particular age groups.

The most demanding scenarios of 5-on-5 modified scrimmage situations in elite basketball.

BACKGROUND: The most demanding scenarios and physical demands of elite basketball 5-on-5 scrimmages are unknown to trainers, although recent advances in microtechnology allows the gaps in this research to be filled. The purpose of this study was to describe and compare the physical demands, through the most demanding scenarios and traditional average measures, of two different 5-on-5 scrimmage situations executed during training sessions in elite male basketball players. METHODS: Physical demand measures (i.e., total distance covered, high-speed running distance, number of high-intensity accelerations actions, number of high-intensity decelerations actions) were collected from 12 players from the Spanish first Division using a Local Positioning System. Measures were compared via a Bayesian inference analysis, considering playing in half-court (HALF) and half-court and transition (HTRAN) conditions for the 5-on-5 scrimmage. RESULTS: This study showed that, irrespective of the approach used to quantify the physical demands (traditional [average measures per minute] and novel rolling average time epoch [most demanding scenarios]), during the HALF condition players covered less and performed a lower number of high-intensity accelerations and decelerations than in HTRAN (Bayesian factor >10 and standardized effect size >0.6). Furthermore, players' physical demands during 5-on-5 scrimmage situations, independently of the court size, were underestimated consistently by the traditional approach. CONCLUSIONS: Quantifying players' physical demands through the rolling approach may provide a more accurate measure of the most intense periods of activity. Based on the physical demands described, HTRAN may be used to help train players to perform optimally during the most physically-stressful scenarios of match-play whereas HALF may be more suitable to be included in warm-ups, recovery sessions and sessions immediately before a match.

Is it enough to use the traditional approach based on average values for basketball physical performance analysis?

Understanding the most demanding scenarios of basketball match-play can optimise training prescription. We established physical demand differences in total distance covered, distance covered at high-speed running, distance covered at high-intensity accelerations and decelerations, number of high-speed running actions and number of high-intensity accelerations comparing the traditional average method with the most demanding scenarios based on 1-minute rolling averages. Physical demand parameters were analysed from 21 elite basketball players according to playing position during a friendly game via local positioning system microtechnology. The results showed that players covered a total distance of 141.3 m·min-1 (p < 0.001; ES = 7.80) and 25.4 m·min-1 (p < 0.001; ES = 4.52) at high-speed running using rolling averages, compared to 66.3 and 3.2 m min-1, respectively, using the traditional average approach. These data represent a very large increase of 113.1% for total distance per minute and 686.4% for high-speed running distance per minute, 252% for the number of high-intensity accelerations and 290.5% for the number of high-intensity decelerations, respectively, demonstrating the relevance of this novel approach. In conclusion, this investigation indicated that the traditional average method underestimates peak physical demands over a 1-minute period during a basketball game. Thus, the average approach should be complemented by analysing the most demanding scenarios in order to have a better understanding of physical demands during basketball competition.

Changes in External Load When Modifying Rules of 5-on-5 Scrimmage Situations in Elite Basketball.

Vazquez-Guerrero, J, Reche, X, Cos, F, Casamichana, D, and Sampaio, J. Changes in external load when modifying rules of 5-on- 5 scrimmage situations in elite basketball. J Strength Cond Res 34(11): 3217-3224, 2020-Constraining tasks are very frequent during the team sports training process; however, most of the effects of these coaching decisions are unknown, which leads to less controlled performing environments, with less chances to promote improvements. The aim of this study was to determine the effects of modifying rules of 5-a-side scrimmage on the physical performance of professional basketball players. Data were collected from 12 elite male players (age, 29.6 ± 4.5 years; height, 1.99 ± 9.6 cm; body mass, 92.1 ± 11.9 kg) from the Spanish first Division of Basketball during thirty-three 5-on-5 scrimmage situations over a 18-week period. Physical demands were assessed using WIMU PRO Local Positioning System (Realtrack Systems, Almeria, Spain) and included total and speed-ranged distance covered, player load, peak speed, number of high-intensity actions, number of total and high-intensity accelerations and decelerations, and peak acceleration. A repeated-measures analysis of variance was used to test the differences in all variables, considering playing in half-court (HALF), half-court and transition (HTRAN), and full-court (FULL) conditions for the 5-on-5 scrimmage drill. Results showed that during the HALF condition, there was less distance covered (effect size [ES] = 3.55), lower peak speeds (ES = 3.00), less player load (ES = 2.79), lesser number of high-intensity actions (ES = 1.45), and lesser number of high-intensity accelerations (ES = 1.44) and decelerations (ES = 1.31) than in FULL. In HTRAN, players covered more distance (ES = 2.42), presented higher player load (ES = 1.88), higher intensity actions (ES = 1.02), and peak speed (ES = 4.22) than in HALF. In conclusion, physical demands can be modulated changing the rules and court size using 5-on-5 scrimmage situations, and this factor should be taken into account when designing training drills and when fine-tuning periodization.

Higher training workloads do not correspond to the best performances of elite basketball players.

The aim of this study was to identify the correspondence between the workload demands in training sessions and the game performance from elite basketball players, according to their specific positions. Data were collected from a professional men's basketball team competing in the Spanish Professional League and Euroleague. Players' activity during the training sessions was measured using WIMU PRO® and the game statistics were used as a measure of game performance. Cluster analysis allowed to classify the training workload and the game performance, whereas correspondence analysis allowed to explore their relationship. In essence, there was no correspondence from the higher workloads with the best performances, on the contrary, the small forwards' best performances corresponded to lower training workouts. Despite their importance, the external measures of load need to be complemented with additional (and valid) measures that can be translated to game performance.

Differences in Physical Demands between Game Quarters and Playing Positions on Professional Basketball Players during Official Competition.

The purpose of this study was to compare physical demands between game quarters and specific playing positions during official basketball competition. Thirteen professional male basketball players from the Spanish 2nd Division were monitored across all 17 regular-season home games. Physical demands were analyzed using a local positioning system (WIMU PRO™, Realtrack Systems S.L., Almería, Spain) and included peak velocity, total distance covered, high-speed running (>18 km·h-1), player load, jumps (>3G), impacts (>8G) and high-intensity accelerations (≥2 m·s-2) and decelerations (≤-2 m·s-2). A linear mixed model was used to test statistical significance (p < 0.05) between independent variables. Furthermore, standardized Cohen's effect size (ES) and respective 90% confidence intervals were also calculated. There was an overall decrease in all variables between the first and fourth quarter during competition. Specifically, total distance covered (p < 0.001; ES = -1.31) and player load (p < 0.001; ES = -1.27) showed large effects between the first and last period. Regarding differences between positions, guards presented significant increased values compared to centers (p = 0.04; ES = 0.51), whereas centers achieved significant larger results and moderate effects in comparison to guards in peak velocity (p = 0.01; ES = 0.88) and jumps (p = 0.04; ES = 0.86). In conclusion, physical demands vary between game quarters and playing positions during official competition and these differences should be considered when designing training drills to optimize game performance.

The Most Demanding Scenarios of Play in Basketball Competition From Elite Under-18 Teams.

The main purpose of this study was to describe the most demanding scenarios of match play in basketball through a number of physical demand measures (high-intensity accelerations and decelerations, relative distance covered, and relative distance covered in established speed zones) for four different rolling average time epochs (30, 60, 180, and 300 s) during an official international tournament. A secondary purpose was to identify whether there were significant differences in physical demand measures among playing positions (centers, guards, and forwards) and levels (two best classified teams in the tournament and remaining teams), match scoring (winning, losing, and drawing), and playing periods (match quarter) at the moment of the most demanding scenarios. Data were collected from 94 male under 18 (U18) elite basketball players (age: 17.4 ± 0.7 years; stature: 199.0 ± 11.9 cm; body mass: 87.1 ± 13.1 kg) competing in a Euroleague Basketball Tournament. Measures were compared via a Bayesian inference analysis. The results revealed the presence of position-related differences [Bayesian factor (BF) > 10 (at least strong evidence) and standardized effect size (δ) > 0.6 (at least moderate)] so that centers covered a lower relative distance at speed zone 1 and had lower high-intensity accelerations and decelerations than guards. However, the Bayesian analysis did not demonstrate the existence of significant differences in any physical demand measure in relation to the playing level, match scoring, and playing periods at the moment of the most demanding scenarios. Therefore, this study provides coaches and strength and conditioning specialists with a most demanding scenario reference on physical demands that can be used as an upper limit threshold in the training and rehabilitation monitoring processes.

Changes in Locomotor Ratio During Basketball Game Quarters From Elite Under-18 Teams.

Quantifying game and training demands in basketball allows to determine player's readiness and optimizes preparation to perform and reduce injury risks. Available research is using tracking technology to perform general descriptions of the game activities at professional levels, but somehow, is not exploring the possibilities of gathering data from new variables that can contribute with complementary information for the coaching staffs. The aim of this study was to identify changes in locomotor ratio, at higher and lower speeds, during the game quarters from elite under-18 basketball teams. Ninety-four male players participated in the study (age: 17.4 ± 0.74 years; height: 199.0 ± 0.1 cm; body mass: 87.1 ± 13.1 kg) from different playing positions, Guards (n = 35), Forwards (n = 42), and Centers (n = 17). Data were gathered from an international tournament and players' movements were measured using a portable ultra-wide band position-tracking system (WIMU PRO®, Realtrack Systems, Almeria, Spain). The following variables were measured: (1) relative distance in different speed zones: walking (<6.0 km·h-1), jogging (6.0-12.0 km·h-1), running (12.1-18.0 km·h-1), high-intensity running (18.1-24.0 km·h-1), and sprinting (>24.1 km·h-1); and (2) player load, vector magnitude expressed as the square root of the sum of the squared instantaneous rates of change in acceleration in each of the three planes divided by 100. Afterward, these variables were used to calculate players' locomotor ratio (player load per meter covered) at higher (running, high-intensity running, and sprinting) and lower speeds (walking and jogging). Results from the locomotor ratio at both lower and higher speeds presented a significant effect for the quarter (F = 7.3, p < 0.001 and F = 7.1, p < 0.001, respectively) and player position (F = 3.1, p = 0.04, F = 9.2, p < 0.001, respectively). There was an increase in the locomotor ratio from game quarter (Q) Q1 to Q4 at lower speeds, but contrary trends at higher speeds, i.e., the values have decreased from Q1 to Q4. Also, forwards and centers of the best teams presented lower values at higher speeds. Altogether, the findings may be used by coaching staffs as a first baseline to elaborate normative behavior models from the players' performance and also to induce variability and adaptation in specific practice planning.

Changes in physical demands between game quarters of U18 elite official basketball games.

PURPOSE: The aim of this study was to describe the physical demands during U18 elite basketball games according to the game quarter and to identify a smaller subset of variables and threshold scores that distinguish players' physical performance in each quarter. METHODS: Data was collected from ninety-four players who participated in the study (age: 17.4 ± 0.74 years; height: 199.0 ± 0.1 cm; body mass: 87.1 ± 13.1 kg) competing in the Euroleague Basketball Next Generation Tournament. Players' movements during the games were measured using a portable local positioning system (LPS) (WIMU PRO®, Realtrack Systems SL, Almería, Spain) and included relative distance (total distance / playing duration), relative distance in established speed zones, high-intensity running (18.1-24.0 km·h-1) and sprinting (> 24.1 km·h-1). player load, peak speed (km·h-1) and peak acceleration (m·s-2) number of total accelerations and total decelerations, high intensity accelerations (> 2 m·s-2) and decelerations (< -2 m·s-2). RESULTS: There was an overall decrease in distance covered, player load, number of high intensity accelerations and decelerations between the first and last quarter of the games in all playing positions. A classification tree analysis showed that the first quarter had much influence of distance covered (above 69.0 meters), distance covered <6.0 km·h-1 and accelerations (> 2 m·s-2), whereas the fourth quarter performance had much influence of distance covered (below 69.0) and distance covered 12.1-18.0 km·h-1. CONCLUSIONS: A significant reduction in physical demands occurs during basketball, especially between first and last quarter for players in all playing positions during basketball games of under 18 elite players.

Physical demands of elite basketball during an official U18 international tournament.

The aims of this study were (a) to compare players' physical demands between different playing positions in elite U18 basketball games and (b) to identify different clusters of performance. Data were collected from 94 male subjects (age: 17.4 ± 0.7 years), competing in a Euroleague Basketball Tournament. Guards covered a greater relative distance than centres and forwards (small to moderate effect). Forwards and guards had more peak accelerations, high accelerations and high decelerations than centres (moderate to large effects). A cluster analysis allowed to classify all cases into three different groups (Lower, Medium and Higher activity demands), containing 37.4%, 52.8% and 9.8% of the cases, respectively. The high accelerations, high decelerations, peak accelerations and total distance covered were the variables that most contributed to classify the players into the new groups. The percentage of cases distributed in the clusters according to playing position, game type (worst vs worst, mixed opposition, best vs best) and team were different. Centres have lower physical demands specially related with the number of accelerations and decelerations at high intensity and the peak acceleration when compared with guards. Each team has a different activity profile, that does not seem to influence the tournament outcome.

Structure of force variability during squats performed with an inertial flywheel device under stable versus unstable surfaces.

The use of unstable surfaces during resistance training has demonstrated a maintenance or reduction on force production. However, the use of unstable surface on force variability has not been assessed using non-linear methods that may be better suited to detect changes in movement variability throughout a given movement. Consequently, this study compared the use of stable vs unstable surfaces on force variability during bilateral squats performed with an inertial flywheel device (Eccoteck, Byomedic System SCP, Spain). Twenty healthy men (mean ±â€¯SD: age 22.9 ±â€¯2.9 years, height 1.81 ±â€¯0.7 m, body mass 76.4 ±â€¯7.6 kg and 1RM back squat 110.9 ±â€¯19.7 kg) with a minimum of four years in resistance training performed six sets of six repetitions of squats at maximal concentric effort with one minute rest between sets. Force output on the vertical axes was measured using a strain gauge and the results were processed using non-linear sample entropy (SampEn). Results showed no differences for any of the dependent variables between stable and unstable conditions. SampEn showed no differences between conditions (chi-squared = 0.048 P = 0.827), while Forcemean and SampEn presented a small correlation (r = 0.184; p < 0.01). No changes in entropy were found over the course of the series. Together, these results suggest that the structure of force variability between stable and unstable surfaces are similar. This lack of difference between surfaces may be due to postural and anticipatory adjustments. Consequently, by introducing unstable surfaces to the flywheel bilateral squat exercise, practitioners may not observe changes in Forcemean and force variability when compared to stable surface training suggesting that increased training volumes or intensity may be required during unstable environments to cause a desired training stimulus.

Entropy measures detect increased movement variability in resistance training when elite rugby players use the ball.

OBJECTIVES: This study described the variability in acceleration during a resistance training task, performed in horizontal inertial flywheels without (NOBALL) or with the constraint of catching and throwing a rugby ball (BALL). DESIGN AND METHODS: Twelve elite rugby players (mean±SD: age 25.6±3.0years, height 1.82±0.07m, weight 94.0±9.9kg) performed a resistance training task in both conditions (NOBALL AND BALL). Players had five minutes of a standardized warm-up, followed by two series of six repetitions of both conditions: at the first three repetitions the intensity was progressively increased while the last three were performed at maximal voluntary effort. Thereafter, the participants performed two series of eight repetitions from each condition for two days and in a random order, with a minimum of 10min between series. The structure of variability was analysed using non-linear measures of entropy. RESULTS: Mean changes (%; ±90% CL) of 4.64; ±3.1g for mean acceleration and 39.48; ±36.63a.u. for sample entropy indicated likely and very likely increase when in BALL condition. Multiscale entropy also showed higher unpredictability of acceleration under the BALL condition, especially at higher time scales. CONCLUSIONS: The application of match specific constraints in resistance training for rugby players elicit different amount of variability of body acceleration across multiple physiological time scales. Understanding the non-linear process inherent to the manipulation of resistance training variables with constraints and its motor adaptations may help coaches and trainers to enhance the effectiveness of physical training and, ultimately, better understand and maximize sports performance.

Are There Potential Safety Problems Concerning the Use of Electronic Performance-Tracking Systems? The Experience of a Multisport Elite Club.

Despite approval of the use of electronic performance-tracking systems (EPTSs) during competition by the International Football Association Board, other team-sport organizations and leagues have banned their use due to "safety concerns," with no evidence to support this assertion. The aim of the current brief report was to provide empirical evidence to support the widespread use of EPTSs across all sports by examining safety issues concerning their use in a multi-team-sport club. Five outdoor football teams (1st team, 2nd team, under 19 [U-19], under 18 [U-18], and 1st team female) and 3 indoor-sport (basketball, futsal, and handball) teams were monitored, accounting for a total of 63,734 h of training and 12,748 h of game time. A questionnaire was sent to all fitness coaches involved, and the clinical history was reviewed for every medical issue reported. Six minor chest contusions were recorded in female football goalkeepers wearing the frontal chest strap (3.17 episodes per 1000 training h). During training, 3 episodes of minor skin abrasion affecting the thoracic area due to wearing vests too tight were recorded in the U-19 football team (0.21 per 1000 h) and 2 episodes in U-18 (0.39 per 1000 h). It must be noted that none of these episodes resulted in lost days of training or games, and none required medical assistance. In conclusion, empirical evidence confirms that EPTSs are safe to use across team sports.

Force Outputs during Squats Performed Using a Rotational Inertia Device under Stable versus Unstable Conditions with Different Loads.

The purpose of the study was to compare the force outputs achieved during a squat exercise using a rotational inertia device in stable versus unstable conditions with different loads and in concentric and eccentric phases. Thirteen male athletes (mean ± SD: age 23.7 ± 3.0 years, height 1.80 ± 0.08 m, body mass 77.4 ± 7.9 kg) were assessed while squatting, performing one set of three repetitions with four different loads under stable and unstable conditions at maximum concentric effort. Overall, there were no significant differences between the stable and unstable conditions at each of the loads for any of the dependent variables. Mean force showed significant differences between some of the loads in stable and unstable conditions (P < 0.010) and peak force output differed between all loads for each condition (P < 0.045). Mean force outputs were greater in the concentric than in the eccentric phase under both conditions and with all loads (P < 0.001). There were no significant differences in peak force between concentric and eccentric phases at any load in either stable or unstable conditions. In conclusion, squatting with a rotational inertia device allowed the generation of similar force outputs under stable and unstable conditions at each of the four loads. The study also provides empirical evidence of the different force outputs achieved by adjusting load conditions on the rotational inertia device when performing squats, especially in the case of peak force. Concentric force outputs were significantly higher than eccentric outputs, except for peak force under both conditions. These findings support the use of the rotational inertia device to train the squatting exercise under unstable conditions for strength and conditioning trainers. The device could also be included in injury prevention programs for muscle lesions and ankle and knee joint injuries.

Force production during squats performed with a rotational resistance device under stable versus unstable conditions.

[Purpose] Force production during a squat action on a rotational resistance device (RRD) under stable and unstable conditions. [Subjects and Methods] Twenty-one healthy males were asked to perform six sets of six repetitions of squats on an RRD on either stable or unstable surfaces. The stable and unstable sets were performed on different days. Muscular outputs were obtained from a linear encoder and a strain gauge fixed to a vest. [Results] Overall, the results showed no significant differences for any of the dependent variables across exercise modes. Forcemean outputs were higher in the concentric phase than in the eccentric phase for each condition, but there were no differences in velocity, time or displacement. The forcepeak was similar in the eccentric and concentric phases of movement under both stable and unstable conditions. There were no significant differences in forcemean between sets per condition or between conditions. [Conclusion] These results suggest that performing squats with a RRD achieves similar forcemean and forcepeak under stable and unstable conditions. The forcepeak produced is also similar in concentric and eccentric phases.

Cambios en la arquitectura muscular y en la velocidad de ejecución de sentadillas en VersaPulley en condiciones estables e inestables en jugadores junior de baloncesto de élite durante una temporada / Mudanças na arquitetura muscular e agachamentos velocidade de execução em VersaPulley em condições estáveis e instáveis em juniores jogadores de basquete de elite durante a temporada / Changes in muscular architecture and execution velocity during squats performed using the VersaPulley under stable and unstable conditions in junior elite basketball players

Los objetivos del presente estudio fueron: a) monitorizar y comparar la velocidadpico de ejecución de sentadillas con VersaPulley (VP) en condiciones estables (CE) y condiciones inestables (CI) en jugadores junior de baloncesto de élite durante una temporada y b) evaluar los cambios en la arquitectura muscular (AM). Siete jugadores junior de baloncesto realizaron el entrenamiento técnico-táctico y de acondicionamiento físico de la temporada (16 horas semanales) incluyendo entrenamiento de fuerza mediante sentadillas con VP en CE y CI. Durante la temporada se evaluó la velocidadpico de ejecución de las sentadillas mediante el sistema T-FORCE. Además, cada 3 meses se valoró la AM del vasto lateral mediante ultrasonidos. Los resultados no mostraron diferencias significativas en la velocidadpico al realizar sentadillas entre ambas condiciones en ningún momento de la temporada, aumentando un 17% en CE y un 23% en CI (p<0,01). El grosor muscular (p= 0,009) y el ángulo de peneación (p<0,05) aumentaron mientras que la longitud de los fascículos no experimentó cambios significativos. El entrenamiento regular de baloncesto y el entrenamiento de fuerza incluyendo sentadillas con VP en CE y CI generaron niveles similares de velocidadpico en ambas condiciones en jugadores de baloncesto júnior de élite. La velocidadpico aumentó tanto en CE como en CI durante la temporada. Además, se produjeron cambios en la AM (AU)

Os objetivos do estudo em questão foram: a) monitorar e comparar a velocidade máxima de execução de agachamento no VersaPulley (VP) em condições estáveis (CE) e condições instáveis (CI) em jogadores juvenis de basquete de elite durante uma temporada e b) avaliar as mudanças na arquitetuta muscular (AM). Sete jogadores juvenis de basquete realizaram o treinamento técnico-tatico e de condicionamento físico da temporada (16 horas semanais) incluindo treinamento de forca através de agachamentos com VP em CE e CI. Durante a temporada monitorizou-se a velocidade máxima de execução dos agachamentos através do sistema T-FORCE. Além disso, a cada 3 meses avaliou-se a AM do vasto lateral através de Ultra-som. Os resultados nao mostraram diferenças significativas na velocidade máxima ao realizar agachamentos entre ambas condições em nenhum momento da temporada, aumentando um 17% em CE e um 23% em CI (p<0,01). A grossura muscular (p=0,009) e o ângulo de penação (p<0,05) aumentaram enquanto que a longitude dos fascículos nao demonstrou mudanças sinificativas. O treinamento normal de basquete e o treinamento de força incluindo agachamentos com VP em CE e CI geraram níveis similares de velocidade máxima em ambas condições nos jogadores de basquete juvenis de elite. A velocidade maxima aumentou tanto em CE como em CI durante a temporada. Além disso, produziu-se mudanças na AM (AU)

The purposes of the present study were to: a) monitor and compare velocitypeak when performing squats with VersaPulley (VP) on stable conditions (CE) and on unstable conditions (CI) in elite junior basketball players during a season and b) assess the changes in muscle architecture (AM). Seven junior basketball players performed the technical-tactical training and the physical fitness of the season (16 weekly hours) adding extra strength training performing squats with the VP under CE and CI. Velocitypeak when performing the squats was assessed during the season through T-FORCE system. Moreover, every 3 months the AM of the vastus lateralis was assessed. Results indicated that velocitypeak did not show significant differences when performing squats under both conditions during the season. Velocitypeak increased 17% under CE and 23% under CI (p< 0.05) increased whilst the fascicle length did not show significant differences. The regular basketball training and the strength training, including squats performed with VP under CE and CI, increased a long de season in a basketball elite junior players. Moreover, we founded changes in AM (AU)