Playing Non-Professional Football in COVID-19 Time: A Narrative Review of Recommendations, Considerations, and Best Practices

Soccer's AI transformation: deep learning's analysis of soccer's pandemic research evolution

Introduction

This paper aims to identify and compare changes in trends and research interests in soccer articles from before and during the COVID-19 pandemic.

Methods

We compared research interests and trends in soccer-related journal articles published before COVID-19 (2018-2020) and during the COVID-19 pandemic (2021-2022) using Bidirectional Encoder Representations from Transformers (BERT) topic modeling.

Results

In both periods, we categorized the social sciences into psychology, sociology, business, and technology, with some interdisciplinary research topics identified, and we identified changes during the COVID-19 pandemic period, including a new approach to home advantage. Furthermore, Sports science and sports medicine had a vast array of subject areas and topics, but some similar themes emerged in both periods and found changes before and during COVID-19. These changes can be broadly categorized into (a) Social Sciences and Technology; (b) Performance training approaches; (c) injury part of body. With training topics being more prominent than match performance during the pandemic; and changes within injuries, with the lower limbs becoming more prominent than the head during the pandemic.

Conclusion

Now that the pandemic has ended, soccer environments and routines have returned to pre-pandemic levels, but the environment that have changed during the pandemic provide an opportunity for researchers and practitioners in the field of soccer to detect post-pandemic changes and identify trends and future directions for research.

Considerations after lockdown and overcoming Covid-19: A systematic review for returning to safe physical exercise practice

Objective

This systematic review aims to understand the problems associated with lockdown and the various conditions of Covid-19 infection and to help prepare athletes and exercise enthusiasts for the safe resumption of sport in a manner that promotes wellness, healthy competition, and a sports industry that survives the current situation. This systematic review was carried out, following the recommendations of the currently pre-established reporting elements for systematic reviews and meta-analyses. The following databases were consulted: ISI Web of Science (WOS), Scopus and Google Scholar. This review includes a total of 19 articles.

News

The results are presented based on three predominant themes: (1) psychological impact produced by SARS-CoV-2; (2) post-Covid-19 cardiac abnormalities and (3) protocols for an adequate return to physical practice.

Prospects and projects

Most of the protocols shown by the various papers are consistent in terms of duration and number of phases. Based on this, the safe return to practice protocol can be divided into four stages of seven days in each phase in order to progress according to the symptoms perceived. In each phase, the physiological demand and efforts necessary to cover the proposed activities are increased until optimal physical condition is recovered.

Bio-secure bubble during the COVID-19 pandemic to host the Asian Football Confederation (AFC) Champions League: A retrospective observational study

Background and Aims

To describe the COVID-19 positivity rate among football players, team staff, and local organizing committee members participated in the Asian Football Confederation (AFC) Champions League (West) tournament organized with the Bio-secure bubble protocol in place.

Methods

A retrospective observational study was carried out to include a total of 2184 participants during the AFC-West tournament in Qatar, which was a 3-week event (September 14-October 3, 2020). This event was undertaken under the Bio-secure bubble protocol, which was developed and implemented for sports events in Qatar during the pandemic. Within 72 h of departure and upon arrival in Qatar, all participants underwent reverse-transcriptase polymerase chain reaction testing (RT-PCR) to diagnose COVID-19. The test was considered positive based on the cycle threshold (cT) value which was <30, whereas, reactive if cT value was ≥30 and <40, and negative (cT > 40).

Results

Of the 2184 participants (528 players, 388 team staff, and 1268 local staff), 916 international participants were tested for COVID-19 PCR upon arrival at the Hamad International Airport, whereas the local staff (n = 1268) were tested 2 days before entering the bubble. The mean age of the players was 27.5 ± 9.8. Fifteen teams participated and as many as 60 matches were played over 3 weeks. Most participants tested negative (95.3%) and 3.9% tests were inconclusive. During the entire tournament, the positivity rate was 2.7% among all participants. Of the total positive cases, 0.8% were positive before entering the bubble system. The remaining (1.9%) tested positive during the tournament phase (19 players, 16 team officials, and 8 organizing committee staff).

Conclusion

Bio-secure bubble protocol operated in a controlled environment presents a minimal risk of COVID-19 infection for hosting international football events. This framework could be benchmarked to resume professional football competitions under unprecedented pandemic situations.

Recommencement of football competition with spectators during the active phase of the COVID-19 pandemic in a Middle Eastern country

Background

With the global spread of COVID-19 infection caused by the severe acute respiratory syndrome coronavirus-2 virus (SARS-CoV-2), all the national and international sports events were ceased early in 2020. The sport activities have been reinstated since then, albeit without spectators. However, several governments have established a variety of risk-mitigation measures to gradually reintroduce the spectators to stadiums.

Objectives

We aimed to evaluate the implementation of a strict health protocol to ensure the resumption of professional football with spectators and to access its effectiveness in limiting the spread of COVID-19 infections within the community.

Methods

This was a retrospective, observational study involving football players, match officials, local organizing committee members, working in close coordination, and over 16,000 spectators in the state of Qatar. We examined data from the Amir Cup final (December 18th, 2020), which was played under a strict protocol that included extensive reverse transcription-Polymerase chain reaction (RT-PCR) testing for players and match officials, as well as the utility of COVID-19 rapid antigen and antibody testings as screening tools for spectators to ensure their safe return to the stadiums. In addition, we reviewed the guidelines and protocols that were put in place to organize Qatar's Amir Cup Football Final, which drew over 16,000 spectators in the stadium.

Results

A total of 16,171 spectators undertook rapid antigen and antibody tests for the Amir cup final (from December16-December18, 2020). Fifteen Spectators (n = 15) returned with a positive result for COVID-19 infection during the final event (positivity rate = 0.12%). All players underwent RT-PCR testing 48 h before the match. None of the players tested positive for COVID-19 infections. 1311 individuals reported having symptoms related to COVID-19 post final of Amir Cup. These spectators were tested for COVID-19 RT-PCR with an overall positivity rate (positive/reactive) to be 0.42% (69/16171).

Conclusion

This report shows a meagre incidence rate of COVID-19 infections during and post-Amir Cup football final. Based on the low infectivity rate reported during and post the Amir Cup, we propose that supervised and controlled resumption of football matches with spectators can be carried out safely following a strict testing and tracing protocol. Similar infection control policies can be replicated with a higher number of spectators.

COVID-19 disease in professional football players: symptoms and impact on pulmonary function and metabolic power during matches

This study aimed at: (1) Reporting COVID-19 symptoms and duration in professional football players; (2) comparing players' pulmonary function before and after COVID-19; (3) comparing players' metabolic power (P_met ) before and after COVID-19. Thirteen male players (Age: 23.9 ± 4.0 years, V̇O_2peak : 49.7 ± 4.0 mL/kg/min) underwent a medical screening and performed a running incremental step test and a spirometry test after COVID-19. Spirometric data were compared with the ones collected at the beginning of the same season. Players' mean P_met of the 10 matches played before COVID-19 was compared with mean P_met of the 10 matches played after COVID-19. Players completed a questionnaire on COVID-19 symptoms and duration 6 months following the disease. COVID-19 positivity lasted on average 15 ± 5 days. "General fatigue" and "muscle fatigue" symptoms were reported by all players during COVID-19 and persisted for 77% (general fatigue) and 54% (muscle fatigue) of the players for 37 ± 28 and 38 ± 29 days after the disease, respectively. No significant changes in spirometric measurements were found after COVID-19, even though some impairments at the individual level were observed. Conversely, a linear mixed-effects model analysis showed a significant reduction of P_met (-4.1 ± 3.5%) following COVID-19 (t = -2.686, p < 0.05). "General fatigue" and "muscle fatigue" symptoms may persist for several weeks following COVID-19 in professional football players and should be considered for a safer return to sport. Players' capacity to compete at high intensities might be compromised after COVID-19.

COVID-19 Confinement Effects on Game Actions during Competition Restart in Professional Soccer Players

The main objective of the present study was to compare high-intensity actions in a week of three matches before and after the COVID-19 lockdown. The observational methodology was used. This study analysed 551 professional soccer players from 22 different Spanish teams (LaLiga Smartbank 2019−2020) by a multi-camera tracking system and associated software (Mediacoach®, Spain). Variables of distances per minute and totals, travelled at High Intensity (HIR), Very High Intensity (VHIR), Sprint (HSR), player’s maximum speed, average speed, and the number of efforts in VHIR and HSR were analysed in the first and second half of the games, the full match, as well as in relation to the playing position. Players who participated in the same number of matches pre- and post-COVID-19 showed an increase in the total minutes played, p < 0.05, and small decreases in game actions, p < 0.05, with an effect size between 0.21 and 0.45, while players who participated in different number of matches pre- and post-COVID-19 showed a performance decrease, p < 0.05, with a size effect between 0.13 and 0.51; this was evident, particularly, for midfielders, p < 0.05, with a size effect between 0.39 and 0.75. The results seem to show that the playing intensity after COVID-19 confinement did not lead to large performance losses, except for midfielders who were the most involved players and showed a higher decrease in performance. The main findings of this study could provide insight to football coaches for rotations in starting line-ups and game substitutions, so as not to affect the intensity levels of the competitions.

Practical Applications for Designing Soccer´ Training Tasks from Multivariate Data Analysis: A Systematic Review Emhasizing Tactical Training

Novel viewpoints have led to an understanding that good soccer performers are capable of continuous decision-making and performing excellent motor skills in a well conditioned mental state. Our aims in this review were to: (a) summarize the effects of different conditions and constraints on a soccer player's response and (b) identify potential training designs for varied soccer tasks from a multivariate perspective, emphasizing tactical training. We performed a systematic literature review according to PRISMA guidelines and identified multiple different player constraints, including model strategies for play, drills designed for varied conditions, and training regimens for the dimensions of the physical demands soccer players will face. The use of match-sized training spaces may improve physical fitness and collective tactical behavior, while smaller spaces may contribute to improving tactical behavior from micro-structures (e.g., 1 vs. 1). Pre-session exercises that accelerate the appearance of fatigue during training may help delay the onset of match fatigue and boost players´ creativity. Pitch modifications (dimensions or boundary modifications), modification of game principles (defending strategies or team formations), and altering the number of players involved or coach instructions may contribute to different players improvements. Differential learning, as a non-linear pedagogy, may induce improvements in all dimensions, but especially in creative thinking.

A Preliminary Study of Pre-Season Taekwondo Preparation Strategy: Personal Isolation Training Effect for Elite Athletes

Background: The global coronavirus disease pandemic (COVID-19) has had a considerable impact on athletic competition and team sports training. Athletes have been forced to train alone at home. However, the isolation training model effects are still unknown. Purpose: This study compared the effects of personal isolation training (PIT) and detraining (DT) on specific sport performances (flexibility, power, reaction time, acceleration, and aerobic capacity) and body composition in elite taekwondo athletes. Methods: Eleven elite taekwondo athletes were recruited as voluntary subjects. Athletes were randomly paired by weight into the personal isolation training group (PIT group: N = 5, age: 21.2 ± 0.4 years, BMI: 22.2 ± 0.8 kg/m²) or detraining group (DT group: N = 6, age: 19.8 ± 0.3 years, BMI: 23.1 ± 1.0 kg/m²). All subjects performed the same training content prior to the pre-test (T1). When the pre-test was completed, all subjects underwent 12 weeks of PIT or DT. Athletes were then administrated the post-test (T2). The athlete’s sport performances and body composition were measured to compare the differences between the two groups (PIT and DT) and two phases (T1 and T2). Results: There were no significant differences in kicking reaction time and flexibility in both groups (p > 0.05). The PIT showed significant improvements in 10 m (10M) sprint performance (p < 0.05), and displayed a progress trend in Abalakov jump performance. In addition, the PIT resulted in a better change response in 10M sprint performance (PIT: −4.2%, DT: +2.1%), aerobic endurance performance (PIT: −10.2%, DT: −18.4%), right arm muscle mass (PIT: +2.9%, DT: −3.8%), and trunk muscle mass (PIT: +2.2%, DT: −1.9%) than DT (p < 0.05). The fat mass percentage showed a negative change from T1 to T2 in both groups (p < 0.05). Conclusions: PIT showed a trend toward better body composition (arm and trunk muscle) and sport performances (10M sprint and aerobic capacity) compared to DT. This finding may provide information on the effectiveness of a personal isolation training model for optimal preparation for taekwondo athletes and coaches. It may also serve as a useful and safe guideline for training recommendations during the coronavirus disease (COVID-19).

Part I: Relationship among Training Load Management, Salivary Immunoglobulin A, and Upper Respiratory Tract Infection in Team Sport: A Systematic Review

Immunoglobulin A (IgA), which is the first line of defense against upper respiratory tract viruses, has been related with training load management. This article aimed to systematically identify and summarize (1) the studies that have found a relationship between training load and salivary IgA in team sports, and (2) the studies that have highlighted a relationship between IgA and upper respiratory tract infection (URTI) in team sports. A systematic review of relevant articles was carried out using two electronic databases (PubMed and WoK) until 3 October 2020. From a total of 174 studies initially found, 24 were included in the qualitative synthesis. This systematic review confirmed that lower values of IgA occurred after greater training load (intensity/volume) and congested periods. In this scenario, a low level of IgA was correlated with higher URTI, which makes training load management mandatory to healthcare avoiding immunosuppression. Therefore, physical fitness and conditioning coaches should carefully manage training load progression, avoiding high-intensity sessions in two consecutive days. In addition, they should not program high-intensity training sessions during at least the two days following competition.