A Systematic Review and Meta-Analysis

Background Soccer is the most popular sport worldwide, with a long history and currently more than 500 million active participants, of whom 300 million are registered football club members. On the basis of scientific findings showing positive fitness and health effects of recreational soccer, FIFA (Fédération Internationale de Football Association) introduced the slogan ‘‘Playing football for 45 min twice a week—best prevention of non-communicable diseases’’ in 2010. Objective The objective of this paper was to perform a systematic review and meta-analysis of the literature to determine the effects of recreational soccer on maximal oxygen uptake ( _ VO2 max). Methods Six electronic databases (MEDLINE, PubMed, SPORTDiscus, Web of Science, CINAHL and Google Scholar) were searched for original research articles. A manual search was performed to cover the areas of recreational soccer, recreational physical activity, recreational small-sided games and _ VO2 max using the following key terms, either singly or in combination: recreational smallsided games, recreational football, recreational soccer, street football, street soccer, effect, maximal oxygen uptake, peak oxygen uptake, cardiorespiratory fitness, _ VO2 max. The inclusion criteria were divided into four sections: type of study, type of participants, type of interventions and type of outcome measures. Probabilistic magnitude-based inferences for meta-analysed effects were based on standardised thresholds for small, moderate and large changes (0.2, 0.6 and 1.2, respectively) derived from between-subject standard deviations for baseline fitness. Results Seventeen studies met the inclusion criteria and were included in the systematic review and meta-analysis. Mean differences showed that _ VO2 max increased by 3.51 mL/kg/min (95 % CI 3.07–4.15) over a recreational soccer training programme in comparison with other training models. The meta-analysed effects of recreational soccer on _ VO2 max compared with the controls of no exercise, continuous running and strength training were most likely largely beneficial [effect size (ES) = 1.46; 95 % confidence interval (CI) 0.91, 2.01; I = 88.35 %], most likely moderately beneficial (ES = 0.68; 95 % CI 0.06, 1.29; I = 69.13 %) and most likely moderately beneficial (ES = 1.08; 95 % CI -0.25, 2.42; I = 71.06 %), respectively. In men and women, the metaanalysed effect was most likely largely beneficial for men (ES = 1.22) and most likely moderately beneficial for women (ES = 0.96) compared with the controls. After 12 weeks of recreational soccer with an intensity of 78– 84 % maximal heart rate (HRmax), healthy untrained men improved their _ VO2 max by 8–13 %, while untrained elderly participants improved their _ VO2 max by 15–18 %. Soccer training for 12–70 weeks in healthy women resulted in an & Peter Krustrup pkrustrup@nexs.ku.dk 1 Faculty of Sport and Physical Education, University of Niš, Niš, Serbia 2 Faculty of Sport and Physical Education, University of Sarajevo, Sarajevo, Bosnia and Herzegovina 3 Faculty of Kinesiology, University of Zagreb, Zagreb, Croatia 4 Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, Exeter, UK 5 Department of Nutrition, Exercise and Sports, Copenhagen Centre for Team Sport and Health, University of Copenhagen, The August Krogh Building, Universitetsparken 13, Copenhagen 2100, Denmark 123 Sports Med (2015) 45:1339–1353 DOI 10.1007/s40279-015-0361-4 improvement in _ VO2 max of 5–16 %. Significant improvements in _ VO2 max have been observed in patients with diabetes mellitus, hypertension and prostate cancer. Conclusion Recreational soccer produces large improvements in _ VO2 max compared to strength training and no exercise, regardless of the age, sex and health status of the participants. Furthermore, recreational soccer is better than continuous endurance running, albeit the additional effect is moderate. This kind of physical activity has great potential for enhancing aerobic fitness, and for preventing and treating non-communicable diseases, and is ideal for addressing lack of motivation, a key component in physical (in)activity.