ABSTRACT
The aim of this study was to systematically review the current literature on blood flow restriction (BFR) as a post-exercise recovery strategy. Experimental studies investigating the effect of BFR on recovery after exercise were included. Only studies meeting the following inclusion criteria were selected: (a) studies investigating about BFR as a post-exercise recovery strategy in athletes and healthy individuals; (b) the full text being available in English; (c) experimental research study design. Studies that exclusively analyzed BFR as a recovery strategy during the exercise (e.g., recovery strategy between bouts of exercise) were excluded. A literature review was conducted on the PubMed, Cochrane, and Web of Science electronic databases up until May 7th, 2023. The main findings were that (i) 9 studies investigated passive BFR as a post-exercise recovery strategy, which shows a significant lack of research in both team and individual sports (especially in female populations), and only 2 studies used active BFR protocols; (ii) although a high quality range of studies was observed, there were methodological limitations such as BFR interventions that were usually conducted after fatiguing protocols or fitness tests, which may not represent the real exercise (e.g., a sprint session of 6 sets of 50 m may induce muscle damage but it does not represent the demands of a team sport like rugby or soccer); (iii) there is a lack of consistency in BFR protocols (e.g., number of cycles or duration of the occlusion-reperfusion periods) for recovery; (iv) some studies showed beneficial effects while others found no positive or detrimental effects of BFR as a post-exercise recovery strategy in comparison with the control/SHAM group. In conclusion, only 11 studies investigated BFR as a post-exercise recovery strategy and there is not any significant amount of evidence in team or individual sports (especially in female populations). BFR could be a potential post-exercise recovery strategy, but practitioners should use caution when applying this method of recovery for their athletes and clients. In addition, it would be of interest for high performance-related practitioners to have a better understanding of the benefits of BFR interventions combined with either active or passive forms of exercise as a post-exercise recovery strategy.
ABSTRACT
This study aimed to benchmark and analyze match performance of elite soccer players from various confederations during the FIFA World Cup Qatar 2022 (Men's WC) and FIFA Women's World Cup Australia and New Zealand 2023 (Women's WC). A total of 128 matches were analyzed using an optical tracking system (n = 1,351 player observations). Players from various national teams were categorized into their respective confederations: Europe (UEFA), South America (CONMEBOL), North/Central America and Caribbean (CONCACAF), Africa (CAF) and Asia and Oceania (AFC/OFC). Generalized Linear Mixed Models and Linear Mixed Models were employed to assess performance differences between confederations. Data revealed that CONMEBOL players in the Men's WC covered less total distance than UEFA players (p = 0.0396; ES = 0.6). However, no differences were found in high-intensity running and sprinting distances across confederations in both tournaments. UEFA players in both competitions typically demonstrated superior technical/tactical performances. In particular, UEFA players in the Women's World Cup made more passes, had 7-16% higher pass completion rates and achieved 10-15% greater line break completion rates compared to those from CAF, CONCACAF and AFC/OFC (p < 0.0001 to p = 0.0199, ES = 0.5-1.3). These findings suggest that UEFA players may possess a tactical/technical edge in international competitions. However, caution should be exercised when interpreting data due to high variations within confederations. This is the first comprehensive study describing match performance between confederations during the Men's and Women's WC, providing valuable insights into the physical and technical/tactical aspects of elite soccer.
ABSTRACT
BACKGROUND: Injury risk in elite youth soccer players is high. Implementing an optimal training load is of utmost importance to reduce the risk of injuries. OBJECTIVE: To conduct a systematic review and best evidence synthesis to explore the effects of internal and external training load on injury risk in elite youth soccer players. METHODS: MEDLINE, Embase, Web of Science, CENTRAL, and CINAHL were searched up until 17 January 2020. Each article had to meet all of the following criteria: (1) the study population consisted of male elite youth soccer players aged between 12 and 21 years; (2) a longitudinal, prospective study design was used; (3) soccer-related injuries were registered (i.e., self-reported or by medical staff); (4) external and/or internal load parameters were described; and (5) the article was published in an English peer-reviewed scientific journal. The quality of the included articles was assessed using the Newcastle-Ottawa Quality Assessment Scale (NOS). A best evidence synthesis was performed to rank the level of evidence. RESULTS: Five studies (2 high quality, 3 low quality) were included. Best evidence synthesis highlighted that there was moderate evidence for (1) no association between 2-, 3-, and 4-week cumulative loads for total distance covered; (2) no association between 1-week workloads (sRPE × duration); and (3) no association between A:C workload ratios (4 weeks) and injury risk. For all other comparisons, only insufficient or conflicting evidence was found. CONCLUSION: There is a paucity of evidence for an association between internal and external training load parameters and injury risk in elite youth soccer players.