Guilherme Tucher, Flávio Antônio de Souza Castro, Nuno Domingos Garrido and Ricardo Jorge Fernandes
Our aim was to analyze physiological, kinematical and performance changes induced by swimming training in regional age‐group athletes. Subjects (15.7 ± 2.2 years old) performed a 4 x 50‐m front‐crawl test at maximal velocity (10 s rest interval) in weeks 2, 4, 9 and 12 of a 15‐week macrocycle. Descriptive statistics were used and the percentage of change and smallest worthwhile change (moderate, 0.6‐1.2, and large, > 1.2) were measured. Lactate concentration in the third, seventh and twelfth minute of recovery decreased significantly between weeks 2‐9 (14.1, 15.7 and 17.6%) and increased between weeks 9‐12 (18.2, 18.6 and 19.8%), with the HR presenting only trivial variations during the training period. Stroke length showed a large decrease in the first 50‐m trial between weeks 4‐9 (6.2%) and a large increase between weeks 9‐12 (3.1%). The stroke rate (in all 50‐m trials) increased significantly between weeks 4‐9 (3‐ 7%) and the stroke index had a moderate to large increase in the first and third 50‐m trial (3.6 and 7.1%, respectively) between weeks 9‐12. The overall time decreased by 1.1% between weeks 2‐12, being more evident after week 4. We concluded that physiological, kinematical and performance variables were affected by the period of training in regional age‐group swimmers.
Sven Schneider, Johannes Sauer, Gregor Berrsche and Holger Schmitt
Pain among young athletes requires special attention given that symptoms occur during the ongoing development of the conditional, and in particular, the motor capacities, and while the musculoskeletal system is in a continuous process of growth. The purpose of this study was to evaluate prevalence, location, context, and coping strategies regarding pain among young athletes. We chose survey data of young elite athletes from the highest level national basketball leagues in Germany, as this meant that health implications may be observed earlier and in a more pronounced manner. The German ‘Adolescents’ and Children’s Health in Elite Basketball study’ (ACHE study), a quantitative survey, was conducted between April and June 2016. Analyses were based on elite basketball players between 13 and 19 years of age from 46 German teams (n = 182). Constant, and to some extent severe pain, was part of daily life of young elite basketball players: eight out of ten players in the highest German leagues suffered from pain at the time of the survey. Knee, leg, and back pain occurred most frequently. For most players, occasional or frequent consumption of analgesics was the norm, in some cases these were also taken “prophylactically”. The consumption of multiple pharmaceutical substances, especially of cyclooxygenase inhibitors such as ibuprofen and diclofenac, is widespread among adolescent elite basketball players. Physicians involved in treating these athletes should address pain and its management preemptively. Coaches, sporting organizations and parents should be involved in this process from an early stage.
Jesús V. Giménez, Anthony S. Leicht and Miguel A. Gomez
The aim of this study was to investigate the physical performance differences between players that started (i.e. starters, ≥65 minutes played) and those that were substituted into (i.e. non‐starter) soccer friendly matches. Fourteen professional players (age: 23.2 ± 2.7 years, body height: 178 ± 6 cm, body mass: 73.2 ± 6.9 kg) took part in this study. Twenty, physical performance‐related match variables (e.g. distance covered at different intensities, accelerations and decelerations, player load, maximal running speed, exertion index, work‐to‐rest ratio and rating of perceived exertion) were collected during two matches. Results were analysed using effect sizes (ES) and magnitude based inferences. Compared to starters, non‐starters covered greater match distance within the following intensity categories: >3.3≤4.2m/s (very likely), >4.2≤5 m/s (likely) and >5≤6.9 m/s (likely). In contrast, similar match average acceleration and deceleration values were identified for starters and non‐starters (trivial). Indicators of workloads including player loads (very likely), the exertion index (very likely), and the work–to‐rest ratio (very likely) were greater, while self‐ reported ratings of perceived exertion were lower (likely) for non‐starters compared to starters. The current study demonstrates that substantial physical performance differences during friendly soccer matches exist between starters and non‐starters. Identification of these differences enables coaches and analysts to potentially prescribe optimal training loads and microcycles based upon player’s match starting status.
Pedro Reche-Soto, Donaldo Cardona-Nieto, Arturo Diaz-Suarez, Alejandro Bastida-Castillo, Carlos Gomez-Carmona, Javier Garcia-Rubio and Jose Pino-Ortega
There has recently been an increase in quantification and objective analysis of soccer performance due to improvements in technology using load indexes such as Player Load (PL) and Metabolic Power (MP). The objectives of this study were: (1) to describe the performance of PL and MP in competition according to the specific role, match‐to‐ match variation, periods of play, game location and match status according to game periods, and (2) to analyze the relationship between both indexes. Twenty‐one national‐level soccer players were distributed in the following specific positional roles: external defenders (ED) (n = 4), central defenders (CD) (n = 4), midfielders (M) (n = 5), external midfielders (EM) (n = 4) and attackers (A) (n = 4). A total of 12 matches played by a Spanish Third Division team during the 2016/2017 season were analyzed. WIMU PROTM inertial devices (RealTrack System, Almeria, Spain) were used for recording the data. The main results were: (1) a performance reduction in both variables over the course of match time, (2) significant differences in both variables based on the specific position, (3) differences in physical demands during the season matches, (4) winning during a game period and the condition of being the visitor team provoked higher demands, and (5) a high correlation between both variables in soccer. In conclusion, different contextual variables influence the external load demands; both indexes are related so they could be used for external load quantification, and it is necessary to analyze physical demands of the competition for a specific and individualized load design in training sessions.
Ronaldo Kobal, Lucas A. Pereira, Katia Kitamura, Anderson C. Paulo, Henrique A. Ramos, Everton C. Carmo, Hamilton Roschel, Valmor Tricoli, Chris Bishop and Irineu Loturco
The aim of this study was to compare the acute effects of performing half squats (HSs) with different loading intensities (1, 3, and 5 repetitions maximum [RM], and 60% 1RM) and a different number of sets (1, 2, and 3) on the countermovement jump (CMJ) performance of 18 highly‐trained male subjects. Participants were submitted to four experimental conditions (1RM, 3RM, 5RM, and 60% 1RM) in randomized order. The CMJ was assessed before and after each set. Differences in CMJ performance between the distinct experimental conditions and individual responses in CMJ performance induced by the different protocols were analyzed via the magnitude‐based inference method. Overall, significant improvements were detected in individual CMJ heights after each activation protocol. It can be concluded that the use of 1 to 3 sets of HSs performed at moderate‐to‐high loads may be an effective strategy to improve jump performance in highly‐trained subjects. Nonetheless, despite the high efficiency of the protocols tested here, coaches and researchers are strongly encouraged to perform individualized assessments within the proposed range of loads and sets, to find optimal and tailored post‐activation potentiation protocols.
Rafael Timon, Silvia Allemano, Marta Camacho-Cardeñosa, Alba Camacho-Cardeñosa, Ismael Martinez-Guardado and Guillermo Olcina
Post‐activation potentiation (PAP) has been defined as a major enhancement of muscular performance following a preload stimulus. The eccentric actions seem to cause a potentiating effect on subsequent explosive exercises. The aim of this study was to determine whether a protocol of squat exercise using an inertial flywheel could have a potentiating effect on jump performance. Sixteen physically active volunteers participated in the study (age: 21.8 ± 2.7 years; body mass index: 23.6 ± 3). All participants completed two different protocols on separate days: a Traditional Protocol (using a half squat with a guided barbell) and an Inertial Flywheel Protocol (using a half squat with an inertial flywheel). Both protocols were similar and consisted of 3 x 6 reps at the load that maximized power, with a 3‐minute rest interval between sets. The squat jump (SJ) was measured by a contact platform at baseline, and four, eight and twelve minutes after the PAP stimulus. A two‐way ANOVA with repeated measures was performed to analyze significant differences over time. There were significant increases of SJ height (p = 0.004, d = 0.665), velocity (p = 0.003, d = 0.688) and power (p = 0.004, d = 0.682) from baseline after the inertial flywheel protocol. A significant interaction effect (time x protocol) was observed, showing that the inertial flywheel protocol had a potentiating effect on the jump performance compared to the traditional protocol, more specifically at 4 and 8 minutes after the PAP stimulus. In conclusion, the inertial flywheel protocol showed a potentiating effect on the squat jump performance, thus this pre‐ conditioning activity could be useful during the warm‐up before the competition.
Jarosław Muracki, Martyna Kumorek, Aleksandra Kisilewicz, Beata Pożarowszczyk, Dennis Boye Larsen, Adam Kawczyński and Shellie Boudreau
Next to winning, minimizing injuries during training and matches is one of the primary goals of professional team sports games. Soreness and pain can be early indicators and risk factors for acute or long‐term injuries. Monitoring pain intensity and duration, as well as potential sources, are useful for planning practices and can be effective means for preventing injury. The aim of this study was to assess the areas and locations of pain in young soccer goalkeepers during a training camp, and to differentiate the area and frequency between pain arising from the muscles (MP), joints (JP), or as a result of an impact (IP). Recordings of the MP, JP, and IP location along with the area were performed using digital body mapping software (Navigate Pain Android app, Aalborg University, Denmark) installed on a tablet personal computer at the end of each training day across a 5‐day training camp. There was a significant difference in the area between the three types of pain (p < 0.001). The post hoc analysis revealed statistically significant differences between the pixel areas of IP versus JP (p < 0.001), IP versus MP (p < 0.001), and JP versus MP (p < 0.001). There was no significant time‐effect for the IP area between 1‐5 days of training (p = 0.610), neither for MP (p = 0.118) or JP (p = 0.797) and no significant difference for all three pain areas between the front and the back side of the body. The body regions most often reported for MP were thighs, while for JP they were groin and hips, and for IP the hips, shoulders, and forearms were most frequently indicated. This is the first study to map and report the pain distribution associated with training across a 5‐day training camp in soccer goalkeepers, and these findings emphasize the value of using digital pain drawings clinically as well as for monitoring the health status of soccer players.
Volker Scheer, Solveig Vieluf, Tanja I Janssen and Hans‐Christian Heitkamp
Trail running is a popular sport, yet factors related to performance are still not fully understood. Lactate thresholds have been thoroughly investigated in road running and correlate strongly with race performance, but to date few data are available about the value in trail running performance prediction. We examined 25 trail runners (age 31.2 ± 5.1 years, BMI 22.2 ± 1.82 kg/m2) with an initial graded exercise test for measurement of VO2max (59.5 ± 5.2 ml.kg‐1.min‐ 1) and lactate thresholds (LT): LTAET (LT aerobic) 1.03 ± 0.59 mmol/l; 11.2 ± 1.1 km/h), IAT (individual lactate threshold) (2.53 ± 0.59 mmol/l; 15.4 ± 1.6 km/h) and LT4 (lactate threshold at 4 mmol/l) (16.2 ± 1.9 km/h). All runners subsequently participated in a 31.1 km XS trail race and 9 runners in a 21 km XXS trail race. Race performance times correlated negatively with the XS trail run (LTAET: r = ‐0.65, p < 0.01; LT4: r = ‐0.87, p < 0.01; IAT: r = ‐0.84, p < 0.01) and regression analysis showed that race performance could be predicted by: LT4: ‐324.15×LT4+13195.23 (R2 = .753, F1,23 = 70.02, p < 0.01). A subgroup analysis showed higher correlations with race performance for slower than faster runners. No correlations were found with the XXS race. Lactate thresholds can be of value in predicting trail race performance and help in designing training plans.
Agostina Casamento-Moran, Stefan Delmas, Seoung Hoon Park, Basma Yacoubi and Evangelos A. Christou
Reacting fast to visual stimuli is important for many activities of daily living and sports. It remains unknown whether the strategy used during the anticipatory period influences the speed of the reaction. The purpose of this study was to determine if reaction time (RT) differs following a steady and a dynamic anticipatory strategy. Twenty‐two young adults (21.0 ± 2.2 yrs, 13 women) participated in this study. Participants performed 15 trials of a reaction time task with ankle dorsiflexion using a steady (steady force at 15% MVC) and a dynamic (oscillating force from 10‐20% MVC) anticipatory strategy. We recorded primary agonist muscle (tibialis anterior; TA) electromyographic (EMG) activity. We quantified RT as the time interval from the onset of the stimulus to the onset of force. We found that a dynamic anticipatory strategy, compared to the steady anticipatory strategy, resulted in a longer RT (p = 0.04). We classified trials of the dynamic condition based on the level and direction of anticipatory force at the moment of the response. We found that RT was longer during the middle descending relative to the middle ascending and the steady conditions (p < 0.01). All together, these results suggest that RT is longer when preceded by a dynamic anticipatory strategy. Specifically, the longer RT is a consequence of the variable direction of force at which the response can occur, which challenges the motor planning process.
Yusuke Ozaki, Takeshi Ueda, Tomohiro Fukuda, Tatsuya Inai, Eri Kido and Daiki Narisako
This research aims to clarify the stride adjustment in the approach of the 400‐m hurdles, and to examine the relationship with 400‐m hurdle performance. Seven male 400‐m hurdlers volunteered for this study. Participants ran three times from the start to the second hurdle. The standard deviation of toe‐hurdle distance and standard deviation of stride length at each step from the start to the first hurdle were calculated. The maximum value of the standard deviation of toe‐hurdle distance was defined as the position at which the athlete starts stride adjustment. The relationships between each variable, 400‐m hurdle personal best, and the ratio of 400‐m hurdle personal best and 400‐m running personal best (400 m/400‐m hurdles) were examined. Results concluded that standard deviation of toe‐hurdle distance gradually increased after the start, reached the maximum value in the latter half of the approach section, and then decreased until the takeoff. Standard deviation of stride length increased significantly from 4 steps before the takeoff. From these trends, it was suggested that athletes seemed to start stride adjustment from the middle stage to the latter half of the approach by sensing stride error accumulation in the middle of the approach. The strides immediately before the takeoff were markedly involved in stride adjustment. Furthermore, the stride adjustment technique to reduce maximum accumulation error of stride evaluated in the approach section was considered associated with the smooth running of the entire 400‐m hurdle race.