Nutritional intake of elite football referees

A Systematic Review of the Physical, Physiological, Nutritional and Anthropometric Profiles of Soccer Referees

BACKGROUND

The importance of soccer referees is widely accepted by international soccer organizations and governing bodies, although there is little research summarizing and appraising the literature on soccer referees. The aim of this study was to systematically review the information related to physical demands, nutrition and physiological profiling of soccer referees.

METHODS

Conforming with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, searches of three electronic databases (Web of Sciences, PubMed and Scopus) were conducted on 24 April 2022. The following search terms were used: (Soccer OR football AND refer*) AND (physical OR physiolo* OR load* OR "body composition" OR "fat mass" OR "fat free mass" OR "body size" OR "nutrition*" OR "nutritional assessment" OR "nutritional intake" OR "macronutrient*" OR "micronutrient*"). The inclusion criteria of the manuscripts written in English were that articles with male and/or female soccer referees and included relevant data concerning performance, physical testing, nutrition, body composition, body size and/or physiology of soccer referees. The tools developed by the National Institute of Health were used to assess risk of bias according to the study design.

RESULTS

In total, 110 manuscripts were included in the present review. Match activities of soccer referees and assistant referees are not comparable. Variation in performance is influenced by competitive level and competitive schedules. Additionally, match performance is often used to validate field protocols. The associations between match indicators and field protocols were not constant across the included studies, particularly in short-maximal tests. An age decline in physical performance was not conclusive. Body size did not discriminate between referees and assistant referees, as well as referees of different competitive levels. Few studies focused on nutritional guidelines among referees, particularly exercise energy expenditure. Energy intake was comparable across studies, but referees did not follow the daily dietary recommendations. Aerobic output was frequently assessed, and it was not comparable to the values for soccer players.

CONCLUSIONS

Although there are decreases in the running profiles of older referees, they maintain the same distances from the ball, and thus, age per se should not be used to define participation at the international level. The assessment of physical fitness warrants future consideration given the levels of fatigue that are apparent at the end of matches. In order to attain ideal levels of body composition, future studies need to provide guidelines for daily energy expenditure and nutritional intake.

TRIAL REGISTRATION

The protocol was published in INPLASY (International Platform of Registered Systematic Review and Meta-Analysis Protocols) with the registration number 202280052 and https://doi.org/10.37766/inplasy2022.8.005 .

Effect of body composition on the athletic performance of soccer referees

Nutrition plays an important role in improving sports performance. The present study aimed at nutritional assessment and examined the relationship between athletic performance and body composition in soccer referees at different levels. The study participants were 120 male soccer referees. 5, 10 and 30 metres (m) sprint tests to measure speed and cooper test for physical fitness were applied in the referees. Participants were divided into two groups as city and class soccer referee. The anthropometric measurements, excluding fat mass (FM) (%), were higher in class referees. Fat mass (%) differences (14⋅1 ± 4⋅28 v. 12⋅3 ± 4⋅41) were statistically significant (P < 0⋅05). Daily energy and nutrient intakes were similar. The inadequacy percentages of energy, vitamin A and calcium were the highest (29⋅2, 30⋅0 and 34⋅2 %, respectively). It was found that a negative significant correlation between FM% and cooper test score (P < 0⋅01; r = -0⋅35), a positive significant correlation between FM% and 5, 10 and 30 m sprint test scores (P < 0⋅01, r = 0⋅38; P < 0⋅01, r = 0⋅38 and P < 0⋅01, r = 0⋅48, respectively). Similarly, there was a negative significant correlation between waist circumference (WC) and cooper test score (P < 0⋅01; r = -0⋅31), a positive significant correlation between WC and 5, 10 and 30 m sprint test scores (P < 0⋅01, r = 0⋅33; P < 0⋅01, r = 0⋅40; P < 0⋅01, r = 0⋅33, respectively). Nutritional recommendations for soccer referees should be made specific to the individual, considering body composition, training intensity and match frequency by a dietician.

Training and development in sport officials: A systematic review

Sport officials make significant contributions to organized sport, yet scientific evidence to inform their specialized training and education at various levels has lagged. While psychological and performance demands of expert sport officials have been well documented, the extent of research about talent and expertise development, training efficacy, and broader developmental trajectories is unclear. This systematic review summarizes 30 years of published findings on the study of training and development of sport officials, including areas of research interest, study designs, and sport official characteristics. A PRISMA systematic review was conducted, utilizing three scientific databases (Web of Science, SportsDiscus, PsycInfo) to identify relevant studies (N = 27). Female participants were generally underrepresented in studies (17%), while football officials were most often represented (79%). Training intervention (59%), retrospective (37%), and cross-sectional comparison (22%) were the main study designs. Expert and near-expert sport officials' training histories and responses to empirically driven isolated-skills training represented the predominant areas of study. Sport-specific, video-based infraction detection tasks were the most frequently used training methods to improve perceptual-cognitive skills for on-field decision-making, however, studies lacked retention measures to on-field performance. Psychological skills training programs were found to have mixed effects and used varied criteria for measuring training efficacy. Physical training showed mainly significant effects on physiological measures and aging influences for on-field performance. More rigorous sport-specific evidence, assessments of training transfer, program efficacy, and macro-developmental trajectory and milestone data are needed to inform training programs and developmental plans.

Body Fat Assessment in International Elite Soccer Referees

Soccer referees are a specific group in the sports population that are receiving increasing attention from sports scientists. A lower fat mass percentage (FM%) is a useful parameter to monitor fitness status and aerobic performance, while being able to evaluate it with a simple and quick field-based method can allow a regular assessment. The aim of this study was to provide a specific profile for referees based on morphological and body composition features while comparing the accuracy of different skinfold-based equations in estimating FM% in a cohort of soccer referees. Forty-three elite international soccer referees (age 38.8 ± 3.6 years), who participated in the 2018 Russian World Cup, underwent body composition assessments with skinfold thickness and dual-energy X-ray absorptiometry (DXA). Six equations used to derive FM% from skinfold thickness were compared with DXA measurements. The percentage of body fat estimated using DXA was 18.2 ± 4.1%, whereas skinfold-based FM% assessed from the six formulas ranged between 11.0% ± 1.7% to 15.6% ± 2.4%. Among the six equations considered, the Faulkner's formula showed the highest correlation with FM% estimated by DXA (r = 0.77; R² = 0.59 p < 0.001). Additionally, a new skinfold-based equation was developed: FM% = 8.386 + (0.478 × iliac crest skinfold) + (0.395 × abdominal skinfold, r = 0.78; R² = 0.61; standard error of the estimate (SEE) = 2.62 %; p < 0.001). Due to these findings, national and international federations will now be able to perform regular body composition assessments using skinfold measurements.

Eating Habits and Body Composition of International Elite Soccer Referees

Soccer referees are a specific group of the athletes' population whose careers peak from 30 to 45 years old. An athlete's performance is not only determined by physical training but also by a lifestyle, e.g. eating habits. The purpose of this study was to verify current eating habits and resulting body composition of a group of elite international soccer referees. At an international FIFA seminar 60 elite international soccer referees (aged 39.2 ± 4.2 years) were enrolled. A body composition assessment was performed with skinfold thickness and bio impedance analysis, while eating habits were evaluated with a multi-pass 24-hour dietary recall. The body composition showed a normal weight condition with a fat content of 11.4 ± 2.5%. Macronutrients showed a low level of carbohydrates (43.6 ± 5.4%) and a high level of fat (40.0 ± 4.5%). Micronutrients showed a low level of calcium, potassium, zinc, magnesium, iodine, vitamin B12 and vitamin B9. Even though their body composition was within the normal range, the current eating habits of elite international soccer referees did not appear to follow the nutrition guidelines. Therefore, it would be advisable to provide knowledge on nutrition for this particular category of sports subjects, an individualized nutritional plan would be advisable, in order to achieve and maintain better performance and appropriate body composition for their role.

Nutritional Adaptations in Elite Soccer Referees: First Evidence and Perspectives

Although the physiological cost of refereeing has been already studied in the literature, especially in soccer umpires, it remains unknown whether referees spontaneously adapt their energy intake during game days. Six national soccer referees completed 24-hour dietary recalls (assisted by the SU.VI.MAX copybook) during a control day (CON) and a day with a game (GAME). The stress level and hunger feelings were assessed using visual analogue scales. Total energy intake, energy derived from macronutrients and energy intake at each meal were analyzed using the Bilnuts nutrition software. Total daily energy intake was not significantly different between conditions (CON: 2270 ± 535 vs. GAME: 2782 ± 293). Energy derived from fat and protein was not different between conditions but the participants ingested more calories derived from carbohydrates during the GAME day (45.5 ± 5.9% vs. 54.9 ± 5.5%, respectively, p<0.05). The calories ingested during snacking were significantly increased during GAME compared with CON (p<0.05). The stress level was significantly higher during GAME and especially before the breakfast, lunch and snack (p<0.05). Hunger feeling was not different between conditions. Referring leads to nutritional adaptations in elite soccer umpires, who tend to increase their energy intake mainly during snacking, by increasing their carbohydrate consumption.