Latest research in football - week 40 - 2023

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases. 


Following studies were retrieved for this week:

#1 Predicting Risk Factors of Lower Extremity Injuries in Elite Women's Football: Systematic Review and Meta-Analysis

Reference: Sports (Basel). 2023 Sep 20;11(9):187. doi: 10.3390/sports11090187.

Authors: Feim Gashi, Tine Kovacic, Arbnore Ibrahimaj Gashi, Arben Boshnjaku, Ismet Shalaj

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Summary: This study identified and analyzed the risk factors of lower extremity injuries (LEI) in elite women football players to improve career and health outcomes. To address this aim, a systematic review and meta-analysis methodology was used. In total, four relevant research articles were identified through database searching and screening using the PRISMA flow diagram. From these articles, eight predictors were identified that influence the risk of LEI among elite women football players: higher body mass index (OR 1.51, 95% CI); previous knee injury (OR 3.57, 95% CI); low normalized knee separation (≤10th percentile) (RR 1.92, 95% CI); all previous injury (previous ACL tear: OR 5.24, 95% CI; ankle sprain: 1.39, 95% CI; knee sprain: 1.50, 95% CI); and previous injury in the lower body (OR 2.97, 95% CI). Meanwhile, lower knee valgus angle in a drop-jump landing (OR 0.64, 95% CI) was found to decrease the risk of LEI among elite women football players.



#2 Determinants of international football performance: Empirical evidence from the 1994-2022 FIFA World Cup

Reference: Heliyon. 2023 Sep 17;9(10):e20252. doi: 10.1016/j.heliyon.2023.e20252. eCollection 2023 Oct.

Authors: Mu Fan, Fei Liu, Dong Huang, Hui Zhang

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Summary: In the past 30 years, the global influence of the FIFA World Cup has continued to grow. According to statistics, the final match of the 2022 World Cup in Qatar attracted an audience of over 3 billion. Nowadays, nations (and regions) emphasize the correlation between overall social progress, football tradition, and national sporting prowess. This study aims to comprehend the dynamics of international football development and secure a competitive edge in the global arena. The study collected panel data from 68 countries (regions) participating in the final stage of the World Cup from 1994 to 2022. It modelled them using a generalized linear mixed model (GLMM) to reveal the macro determinants of success and winning patterns in international football performance. The findings show that (1) football tradition's "characteristic values" (e.g. World Cup host, the experience of hosting the World Cup and the number of all-time World Cup winners) and national comprehensive sporting strength (as represented by the Olympic Games results) have significantly contributed to the national team's World Cup performance; (2) the country's Human Development Index (HDI) has a significant negative impact on World Cup performance; (3) the history of football participation (e.g. the number of years of membership in the Intercontinental Football Association (IFA), history of professional leagues) will have little impact on World Cup performance; (4) two interactive variables: population scale × national comprehensive sporting strength (GPOP × CSOGMedals) and economic level × football tradition (lnGDP × PLHistory), have a negative and positive combined effect on World Cup performance, respectively.



#3 Contemporary practices of physical trainers in professional soccer: A qualitative study

Reference: Front Psychol. 2023 Sep 19:14:1101958. doi: 10.3389/fpsyg.2023.1101958. eCollection 2023.

Authors: Joel Barrera-Díaz, António J Figueiredo, Adam Field, Bruno Ferreira, Sérgio M Querido, João Renato Silva, João Ribeiro, Ismael Pinto, Patricio Cornejo, Hernan Torres, Alvaro Saffa, Hugo Sarmento

Summary: Physical trainers (PTs) are integral for managing load, reducing injury and optimizing performance in professional soccer. However, little is known about how this practitioners operate in the applied setting and how some of the nuances experienced influence practice. This study explored the contemporary practices of PTs in professional soccer. Semi-structured interviews were undertaken with eight PTs from different professional teams in European and South American leagues. Interview questions were designed to extract information on the evaluation of physical abilities, monitoring and control of training and injury prevention. Subsequently, the interviews were video-recorded, transcribed, translated and analyzed using a content analysis approach. The results suggest that the evaluation of physical capacities is carried out by PTs at the beginning of the preseason. It also appears that it is attempted that this process of regular testing is applied during the competitive period, with most participants conducting partial physiological and physical evaluations at different stages throughout the competitive season. In relation to the monitoring and control of training, subjective feedback scales are used to estimate the internal load, and the use of GPS devices is common to quantify external loads. Injury prevention programmes were implemented by all participants and were generally in a multi-component format focused on preventing or optimizing physical capabilities. These insights can be used as a scientific reference point to inform applied practice in professional soccer, especially for practitioners that are inexperienced and aspiring to enhance how they operate in the field. Future investigations should explore the practices of PTs in detail and across a wider network in order to gain deeper and comprehensive insights into the applied soccer environment.



#4 An Unlikely Cause of Groin Pain: Obturator Externus Tear in a Professional Soccer Player

Reference: Cureus. 2023 Sep 3;15(9):e44612. doi: 10.7759/cureus.44612. eCollection 2023 Sep.

Authors: Rui Silva, Adriana Pereira, Sérgio Rodrigues-Gomes, Tiago Lopes

Summary: Groin pain is a common and complex problem in athletes, especially soccer players, associated with a wide variety of possible injuries in numerous anatomical structures. One of the causes of groin pain is damage to the deep muscles of the hip region, with isolated traumatic injury of the obturator externus muscle rarely described and probably underdiagnosed. This report describes a clinical case of a soccer player who presented with acute hip pain and buttock pain resulting from a rapid change of position in load, associated with pain with active hip external rotation and passive internal rotation. MRI demonstrated the presence of subaponeurotic/myo-aponeurotic obturator externus muscle tear. A conservative treatment was decided, targeting pain reduction and progressing range of motion gain and muscle strengthening of the stabilizing muscles of the pelvis and hip, and subsequently, it led to re-athletisation, with soccer-specific exercises. Return to play was 23 days after injury. This case shows that a high level of suspicion is necessary for the correct diagnosis; treatment is generally conservative and the isolated rupture of the external obturator can be considered relatively benign. However, it has the potential to be associated with a long period of absence from training and games.



#4 Physical demands in a small-sided soccer game: a comparison between arbitrary and individualized speed and metabolic power thresholds

Reference: J Sports Med Phys Fitness. 2023 Oct 4. doi: 10.23736/S0022-4707.23.15112-7. Online ahead of print.

Authors: Victor Staibano, Alexandre Moreira, Valéria L Panissa, Marcelo Marques, Emerson Franchini

Summary: This study compared the arbitrary and individualized speed and metabolic power (P<inf>met</inf>) intensity thresholds in a small-sided game (SSG) regarding: 1) distance covered; 2) variations of the physical parameters during the SSG; and 3) associations with physical fitness. Twenty-four amateur soccer players (age: 20.0±1.7 years; height: 176.4±4.2 cm; body mass: 67.6±3.2 kg), after being tested for maximal aerobic speed (MAS) and maximal sprinting speed (MSS), participated in a SSG in a separate session and were monitored with global positioning systems (GPS). The distance covered was classified into three intensity zones for each variable (speed and P<inf>met</inf>) using arbitrary and individualized zones based on MAS. There were differences in the distance covered between methods in zones 1 and 2 for both speed and P<inf>met</inf> (P<0.001), and in zone 3 only for P<inf>met</inf> (P<0.001). There were no variations in any variable analyzed during the SSG. MAS was positively correlated with the distance covered in zone 3 in the arbitrary speed (r=0.67; P<0.001) and P<inf>met</inf> (r=0.60; P<0.01). MSS was negatively correlated with the distance covered in zone 3 in the individualized speed (r=-0.49; P<0.05) and P<inf>met</inf> (r=-0.48; P<0.05). This study showed that arbitrary and individualized provide different information. While the individualized method could be used to monitor physical demands, the arbitrary could be used to assess running physical performance.



#5 Combined influence of psychological and biomechanical factors in muscular loads in soccer : A new approach for the prevention of muscle injuries

Reference: Orthopadie (Heidelb). 2023 Oct 2. doi: 10.1007/s00132-023-04437-8. Online ahead of print. [Article in German]

Authors: Simon Auer, Simone Kubowitsch, Sebastian Dendorfer

Summary: When mental stress and musculoskeletal loading interact, the risk for injury increases due to altered body kinematics and increased muscle tension. These changes can be detected with musculoskeletal models, and mental loading and stress must be analyzed at emotional, cognitive, and behavioral levels. To investigate these kinematic and loading changes under stress, competitive athletes were subjected to mental stress during highly dynamic movements, and musculoskeletal models were used to analyze the biomechanical loading. It was shown that under mental stress, independent of the subjective perception, a strong change in muscle forces can occur. Accordingly, competitive athletes should undergo screenings to assess individual movement patterns and promote general stress resilience.



#6 Hyper-acute effects of sub-concussive soccer headers on brain function and hemodynamics

Reference: Front Hum Neurosci. 2023 Sep 14:17:1191284. doi: 10.3389/fnhum.2023.1191284. eCollection 2023.

Authors: Carissa Grijalva, Dallin Hale, Lyndia Wu, Nima Toosizadeh, Kaveh Laksari

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Summary: Sub-concussive head impacts in soccer are drawing increasing research attention regarding their acute and long-term effects as players may experience thousands of headers in a single season. During these impacts, the head experiences rapid acceleration similar to what occurs during a concussion, but without the clinical implications. The physical mechanism and response to repetitive impacts are not completely understood. The objective of this work was to examine the immediate functional outcomes of sub-concussive level impacts from soccer heading in a natural, non-laboratory environment. Twenty university level soccer athletes were instrumented with sensor-mounted bite bars to record impacts from 10 consecutive soccer headers. Pre- and post-header measurements were collected to determine hyper-acute changes, i.e., within minutes after exposure. This included measuring blood flow velocity using transcranial Doppler (TCD) ultrasound, oxyhemoglobin concentration using functional near infrared spectroscopy imaging (fNIRS), and upper extremity dual-task (UEF) neurocognitive testing. On average, the athletes experienced 30.7 ± 8.9 g peak linear acceleration and 7.2 ± 3.1 rad/s peak angular velocity, respectively. Results from fNIRS measurements showed an increase in the brain oxygenation for the left prefrontal cortex (PC) (p = 0.002), and the left motor cortex (MC) (p = 0.007) following the soccer headers. Additional analysis of the fNIRS time series demonstrates increased sample entropy of the signal after the headers in the right PC (p = 0.02), right MC (p = 0.004), and left MC (p = 0.04). These combined results reveal some variations in brain oxygenation immediately detected after repetitive headers. Significant changes in balance and neurocognitive function were not observed in this study, indicating a mild level of head impacts. This is the first study to observe hemodynamic changes immediately after sub-concussive impacts using non-invasive portable imaging technology. In combination with head kinematic measurements, this information can give new insights and a framework for immediate monitoring of sub-concussive impacts on the head.



#7 In professional football the decline in high-intensity running activities from first to second half is more pronounced in players with a fast muscle typology

Reference: Scand J Med Sci Sports. 2023 Oct 4. doi: 10.1111/sms.14508. Online ahead of print.

Authors: Freek Van de Casteele, Dieter Deprez, Jan Van Haaren, Wim Derave, Eline Lievens

Summary: Muscle typology is heterogeneous among national level football (soccer) players, but positional differences remain unclear. Furthermore, fast typology (FT) individuals fatigue more than slow typology (ST) individuals in lab conditions. Therefore, we investigated if muscle typology is different between playing positions and if the decay in high-intensity activities from the first to the second half is larger in FT football players than in ST players. We estimated muscle typology in 147 male professional football players by measuring soleus and gastrocnemius muscle carnosine via proton magnetic resonance spectroscopy. Players were classified as ST, intermediate typology (IT) or FT and categorized as goalkeeper, center back, full back, midfielder, winger or forward. Across four seasons in-game distances covered in multiple running speed, acceleration and deceleration zones were collected during the first and second half. We found no differences in muscle typology between positions (p = 0.412). FT players covered 10.9% more high acceleration distance (>3 m.s-2 ) in the first half than ST players (p = 0.021) and high acceleration distance decay was larger for FT players (-12.4%) than ST (-7.7%; p = 0.006) and IT players (-7.3%; p = 0.010). Moreover, the decline in distance covered in several high-intensity zones tended to be larger in FT players (-11.2% high-intensity >15 km.h-1 ; -12.7% high deceleration <-3 m.s-2 ; -11.5% medium acceleration 2-3 m.s-2 ) than in ST players (-7.1% high-intensity; -8.1% high deceleration; -8.1% medium acceleration; 0.05 < p < 0.1). In conclusion, possessing a particular muscle typology is not required to play any football position at the national level. However, there are indications that FT players might fatigue more toward the end of the game compared to ST players.



#8 Decision making influences movement variability and performance of high-level female football players in an elastic resistance task

Reference: Front Psychol. 2023 Sep 15:14:1175248. doi: 10.3389/fpsyg.2023.1175248. eCollection 2023.

Authors: Sílvia Tuyà Viñas, Bruno Fernández-Valdés Villa, Carla Pérez-Chirinos Buxadé, Jacob González, Gerard Moras Feliu

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Summary: The inclusion of sport-specific constraints in resistance training promotes the development of player abilities in an integrated way, which maximises the effectiveness of player adaptations induced by training. Considering that perceptual-cognitive abilities play a fundamental role in football, decision making could be introduced to enhance the cognitive similarity of resistance tasks to sport actions. However, it is unknown how decision making as a constraint could affect the player during an elastic resistance task. Therefore, the aim of this study was to investigate the effects of decision making of high-level female football players on movement variability and performance during an elastic band resistance task. Twenty-three high-level female football players performed the elastic resistance task with a ball, both as attackers and as defenders without decision making (NDM) and with decision making (DM). The movement variability was quantified using the sample entropy derived from the acceleration recorded with an accelerometer placed at the lower back of each player. The passing accuracy of the attacker was quantified using a scoring scale. Results revealed that adding decision making to an elastic resistance task increased the movement variability of the defender but did not affect the movement variability of the attacker. In contrast, the passing accuracy of the attacker was reduced. Overall, the attacker had a higher movement variability compared to the defender. These findings suggest that decision making, as a football-specific constraint, can enhance the potential of an elastic resistance task in training. This is due to the fact that it reduces control and regularity of movement for the defensive role player and increases technical difficulty for the attacking role player. Furthermore, these effects are beneficial, as they can promote the adaptive processes necessary to optimise the performance of the players.



#9 Impact of COVID-19 lockdown on injury risk in Qatar's professional football

Reference: J Sci Med Sport. 2023 Sep 19:S1440-2440(23)00410-3. doi: 10.1016/j.jsams.2023.09.008.

Authors: Karim Chamari, Yorck Olaf Schumacher, Mokhtar Chaabane, Raouf Nader Rekik, Souhail Chebbi, Ramadan Daoud, Lena Kristin Bache-Mathiesen, Khalid Alkhelaifi, Roald Bahr, Montassar Tabben

Summary: The aim was to compare injury incidence, burden and characteristics between the pre- and post-COVID-19 lockdown periods in Qatari professional football. Injury and exposure data for two post-COVID-19 lockdown periods [early post-lockdown period: short-term ~2 months (54 matches) and late post-lockdown period: long-term 8-months (183 matches)] were compared to the benchmark of the same periods from the three previous seasons (2017/18-2019/20). We observed no difference in overall, training or match incidence between early post-lockdown period and the benchmark reference. However, this short-term period resulted in lower burden for overall- (RR 0.80, P < 0.0001), training- (RR 0.73, P < 0.0001) and match-injuries (RR 0.40, P < 0.0001) compared to the benchmark. During late post-lockdown period match injury incidence (RR 0.72, P = 0.0010) and match injury burden (RR 0.69, P < 0.001) were lower than the benchmark. In contrast, both overall- (RR 1.30, P < 0.001) and training-injury burden (RR 1.65, P < 0.001) were higher. A significant increase in adductor strains in both post-lockdown periods was observed. Immediately after the COVID-19 lockdown (short-term effect), there was no difference in injury incidence but a lower injury burden compared to benchmark. Moreover, the rapid return to competition for the successive season (long-term effect) was associated with a higher overall- and training-injury burden, but a lower match-injury burden compared to the benchmark.



#10 Validity and Reliability of the Acceleration-Speed Profile for Assessing Running Kinematics' Variables Derived From the Force-Velocity Profile in Professional Soccer Players

Reference: J Strength Cond Res. 2023 Oct 16. doi: 10.1519/JSC.0000000000004637. Online ahead of print.

Authors: Antonio Alonso-Callejo, Jorge García-Unanue, Marc Guitart-Trench, Carlos Majano, Leonor Gallardo, Jose Luis Felipe

Summary: This research aim to assess the validity and reliability of the acceleration-speed profile (ASP) for measuring the mechanical variables of running kinematics when compared with the force-velocity profile (FVP) obtained by reference systems. The ASP and FVP of 14 male players of an elite football club were assessed during a competitive microcycle. Three ASPs were tested according to the number and type of sessions included in its plotting (ASP1: 5 training sessions and competitive match; ASP2: 5 training sessions; ASP3: competitive match). Force-velocity profile was tested 4 days before match (MD-4) with a 30-m linear sprint using 3 previously validated devices (encoder, mobile App, and global positioning system). Level of significance was p < 0.05. Acceptable reliability (intraclass correlation coefficient > 0.5) was found between the ASP1 and the encoder for all variables (F 0 -A 0 , V 0 -S 0 , and V max ). The more reliable ASP method was the ASP1 showing a lower bias than the ASP2 and ASP3 methods for almost all variables and reference systems. For ASP1, lower mean absolute error (MAE: 0.3-0.5) and higher correlation (P-M corr: 0.57-0.92) were found on variables related to the velocity in comparison with variables related to the early acceleration phase (F 0 -A 0 ; MAE: 0.49-0.63; P-M corr: 0.13-0.41). Acceleration-speed profile, when computed with data from a complete competitive week, is a reliable method for analyzing variables derived from velocity and acceleration kinematics. From these results, practitioners could implement ASP and the applications of the FVP previously studied, such as resistance training prescription, performance assessment, and return-to-play management.



#11 Injuries in professional women's elite soccer players in Kosovo: epidemiological injury study

Reference: BMC Sports Sci Med Rehabil. 2023 Oct 12;15(1):131. doi: 10.1186/s13102-023-00746-9.

Authors: Feim Gashi, Tine Kovačič, Ismet Shalaj, Bekim Haxhiu, Arben Boshnjaku

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Summary: An emphasis has been given lately towards women's engagement together with their potential in soccer. As this sport develops with athletes becoming more physically fit and skilled, it is unclear what the consequences in terms of injuries are. Having this in mind, this study aimed to investigate the major injuries that occur in women's soccer players. This descriptive epidemiological study invited all 286 women's soccer players from the 12 participating women clubs in the Kosovo 1st Soccer League (elite football level) during the 2021/2022 season, out of which 142 from 12 clubs participated. Exposure time for 1000 h of playing and training were recorded in addition to the anthropometric data, playing position, and prior injury history during the end of the season, practice, and match. The exact type of injury, severity, and post-injury recovery time, as well as the circumstances surrounding the injuries, were recorded. In total 84 injuries were registered with an overall injury ratio (IR) being 3.21 (CI: 2.56, 3.98) injuries/1000 exposure hours. During the competitive season, each player sustained 1.4 injuries on average. IRs were significantly higher during competition (n = 50; IR = 1.57; CI: 1.52, 1.62) compared to training (n = 34; IR = 0.26, CI: 0.25, 0.27). Out of a total of 142 women players, 84 (59.2%) injuries occurred, and no record of injuries was made in 58 (40.8%) players. The overall IR was observed to be 3.21 (CI: 1.24, 3.27), with moderate and severe injuries accounting for 38.1% of total injuries (each), followed by mild (16.7%) and minimal (7.1%) injuries. The women IR in Kosovo women's soccer players is low while being circa 11% below the international average. Almost 2 out of every 4 injuries were categorized as traumatic, with the IRs being more than 5-fold larger during games than during training. Additionally, these findings emphasize the higher rate of injuries amongst younger athletes, suggesting caution to be taken by the coaches when planning for the match. The collected data may help coaches and trainers create more targeted women's soccer injury prevention programs.



#12 The Homeless World Cup through storytelling: The narratives of Street Soccer players from Scotland and the USA

Reference: Psychol Sport Exerc. 2023 Oct 9:102549. doi: 10.1016/j.psychsport.2023.102549. Online ahead of print.

Authors: Jordan A Donnelly, Meredith A Whitley, Daryl T Cowan, Sara McLaughlin, Rosie Arthur

Summary: The purpose of this paper was to explore: (a) What stories do the Street Soccer players draw upon to construct meaning around their experiences of trauma, social exclusion, and homelessness? and (b) What stories are linked to the subjective sport programming experience and resulting future orientations? A longitudinal narrative approach was adopted with semi-structured interviews conducted with players from Scotland and the United States (n = 16, 7 female, 9 male, M age = 27.5) across three time points. Interviews were also conducted with significant others (n = 13) at time point three. All data were analyzed using thematic narrative analysis and represented in creative non-fiction approaches through three composite narratives. These narratives depicted visceral accounts of complex and developmental trauma, along with consequential experiences that unfolded before, during, and after the Homeless World Cup. While both preparing for and attending the event, players recalled concurrent feelings of anxiety and pride which manifested in various resilient and maladaptive coping behaviors. As the stories progressed, players battled a post event crash by engaging in support seeking and/or self-destructive behaviors before positive implications of the Homeless World Cup materialized. Through creative narrative approaches, this study presents novel and engaging accounts of players' experiences before, during, and after the event. We also identify potential safeguarding concerns that can be addressed through trauma-informed practices.



#13 Are non-starters accumulating enough load compared with starters? Examining load, wellness, and training/match ratios of a European professional soccer team

Reference: BMC Sports Sci Med Rehabil. 2023 Oct 10;15(1):129. doi: 10.1186/s13102-023-00743-y.

Authors: Rafael Oliveira, Rui Canário-Lemos, Ryland Morgans, Tiago Rafael-Moreira, José Vilaça-Alves, João Paulo Brito

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Summary: The aims of the study were to: (i) compare accumulated load and wellness between starters and non-starters of a European professional soccer team; (ii) analyze the relationships between wellness and load measures and; (iii) compare training/match ratio (TMr) of external and internal load between starters and non-starters. Ten players were considered starters while seven were classified as non-starters over a 16-week period in which six training sessions and match day (MD) were considered in each weekly micro-cycle. The following measures were used: wellness (fatigue, quality of sleep, muscle soreness, stress, and mood); load (rated of perceived exertion (RPE), session-RPE (s-RPE), high-speed running (HSR), sprinting, accelerations (ACC) and decelerations (DEC)). Accumulated wellness/load were calculated by summing all training and match sessions, while TMr was calculated by dividing accumulated training load by match data for all load measures and each player. Mann-Whitney U test was used for wellness variables, while independent T-test was used for the remaining variables to compare groups. Moreover, relationships among variables were explored using the Spearman's Rho correlation coefficient. The main results showed that non-starters presented higher significant values for fatigue (p < 0.019; g = 0.24) and lower significant values for duration (p < 0.006; ES = 1.81) and s-RPE (p < 0.001; ES = 2.69) when compared to starters. Moreover, positive and very large correlation was found between quality of sleep and RPE, while negative and very large correlation were found between stress and deceleration, and mood and deceleration (all, p < 0.05). Finally, non-starters presented higher values in all TMr than starters, namely, RPE (p = 0.001; g = 1.96), s-RPE (p = 0.002; g = 1.77), HSR (p = 0.001; g = 2.02), sprinting (p = 0.002; g = 4.23), accelerations (p = 0.001; g = 2.72), decelerations (p < 0.001; g = 3.44), and duration (p = 0.003; g = 2.27). In conclusion, this study showed that non-starters produced higher TMr in all examined variables despite the lower match and training durations when compared with starters, suggesting that physical load was adjusted appropriately. Additionally, higher RPE was associated with improved sleep while higher number of decelerations were associated with decreased wellness, namely, stress and mood for non-starters.



#14 Using Microtechnology and the Fourier Transform for the Analysis of Effective Activity Time in Professional Soccer

Reference: J Strength Cond Res. 2023 Oct 6. doi: 10.1519/JSC.0000000000004615. Online ahead of print.

Authors: José M Oliva-Lozano, Paweł Chmura, Paulino Granero-Gil, José M Muyor

Summary: This study aimed to investigate the use of the fast Fourier transform (FFT) for the analysis of effective activity time in professional soccer by (a) exploring the relationship between this variable and standard external load parameters and (b) analyzing the effective activity time during official professional soccer matches. Twenty-six male players participated in the study. Each player was categorized as midfielder, central defender, full-back, wide-midfielder, or forward. Tracking systems based on inertial sensors (4 3D accelerometers, 3 3D gyroscopes, and 1 magnetometer), and global positioning systems technology were used to collect external load measures for 35 matches. Each match was analyzed considering 15-minute periods to explore the evolution of effective activity time during the matches. The extra time from each match was also included. Fast Fourier transform duration may be a representative variable of effective activity time, given the strong positive correlation with the external load variables (p < 0.001). The linear regression analysis showed that the variables that significantly contributed to the model (R2 = 0.97) were the total of steps and the distance covered. The mean effective activity time in soccer match play was ∼48.69 minutes. This time significantly changed depending on factors such as the period of the match (F = 239.05; p < 0.001; ηp2 = 0.60) or playing position (F = 16.99; p < 0.001; ηp2 = 0.06). The greatest effective activity time was observed for all playing positions in the 0'-15' period. However, the 60'-75' period showed the lowest effective activity times compared with the rest of the 15-minute periods for all positions except for forwards (75'-90'). From a practical standpoint, sports performance practitioners may consider these results to improve the individualization of training and match demands. Also, a more accurate indicator of exercise intensity may be obtained (e.g., multiplying the rating of perceived exertion by the effective activity time).



#15 Effects of Upper-Body and Lower-Body Conditioning Activities on Postactivation Performance Enhancement During Sprinting and Jumping Tasks in Female Soccer Players

Reference: J Strength Cond Res. 2023 Oct 6. doi: 10.1519/JSC.0000000000004562. Online ahead of print.

Authors: Vinicius Santos da Silva, Fábio Yuzo Nakamura, Petrus Gantois, João Nuno Nogueira Gouveia, Javier Peña, Marco Beato, Eduardo Abade

Summary: This study aimed to investigate the postactivation performance enhancement (PAPE) effects of "specific" (half-back squat) and "nonspecific" (bench press) conditioning activities on sprinting and jumping performances in female soccer players. Fourteen players (mean ± SD: age = 22.3 ± 4.0 years; body mass = 60.2 ± 7.8 kg; height = 164.1 ± 4.2 cm) competing at national level (first League) participated in this within-subject crossover study. The players performed a warm-up protocol including 3 sets of 3 repetitions of half-back-squat or bench press exercises at 90% 1RM or a warm-up protocol without lifting weights (i.e., control condition). Forty-meter shuttle sprints (20 + 20 m with change of direction [COD-180°]), countermovement jump (CMJ), and horizontal jump (HJ) performances were recorded 6 minutes after the conditioning activities protocols or the control condition. Nonsignificant large positive effects were found for the HJ after the half-back-squat (ES = 1.68; p > 0.05) and bench press (ES = 1.68; p > 0.05) protocols. Although nonsignificant, HJ changes (Δ = 0.07 m) were greater than the smallest worthwhile change (0.02 m) and standard error of measurement (0.03 m) after both conditioning activities. Moreover, no significant changes were found for sprint and CMJ performance after neither half-back-squat nor bench press protocols (p > 0.05). In conclusion, both specific and nonspecific conditioning activities using heavy loads (i.e., 90% 1RM) may be suitable to enhance individual HJ. Finally, both conditioning activities are potentially ineffective for increasing sprint and CMJ performance in the context of this study.



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