Football is among the most popular sports that lasts ninety minutes with a fifteen-minute break after the first forty-five minutes. Previous studies suggest players cover around ten to twelve kilometres during the ninety minutes (Hills & Russell, 2017). A football performance involves both aerobic and anaerobic metabolism, as well as running and sprinting. The players utilize energy differently when playing football, linked to carbohydrate ingestion. Carbohydrates are considered sources of glucose directly absorbed into the bloodstream to provide the energy required during the match. Several studies show that carbohydrate ingestion significantly affects football performance directly and indirectly. Findings show that carbohydrate ingestion increases exhaustion time and reduces muscle glycogen utilization following intense movements. However, some studies have shown that the role of carbohydrates is limited depending on the glucose production rate after ingestion. This paper provides a comprehensive and critical literature review on the role of carbohydrate indigestion in football performance.
Discussion
Ingestion of carbohydrates before and during a football match affects the plasma concentration, glucose and inflammatory response. In a study conducted by Mizuno et al. (2016), the effect of carbohydrates on the players did not correlate with the time of ingestion. Seven football players participated in three trials where they ingested 1.0 g/kg of carbohydrate gel before participating in a 45-minute running exercise. The participants ingested 0.5 g/kg of carbohydrate gel before embarking on the second part of the running exercise. The third trial acted as the experiment control as they ingested a placebo in similar intervals. Blood tests indicated that the glucose and serum levels were higher when the participants ingested 1.0 g/kg of carbohydrate gel than the placebo. Factors such as jump heights, fatigue, heart rate, muscle injuries, and inflammatory responses were not significantly affected. The findings in the study were in contrast to other experiments that showed carbohydrate ingestion affected running performance and increased the exhaustion time (Mizuno et al., 2016). The inflammatory cytokine release was steady throughout the ninety minutes despite ingesting carbohydrate gel, which is linked to its low impact on anaerobic metabolism. Goedecke et al. reported that carbohydrate intake demonstrated an insignificant effect on overall football performance and only increased the exhaustion time. In the study, 22 soccer players aged between 24 to 31 years ingested either 700 mL of a 7 per cent carbohydrate drink or a placebo drink in trials performed in a 7-day interval. The effect of carbohydrates was determined by analyzing agility, perceived exertions, and fatigue time. The level of fatigue was attained by calculating the body max, which is a lower figure translated to high fatigue. The results indicated that participants who ingested 7% carbohydrate had more extended fatigue than the placebo in the two trials. Before the experiment, players maintained their regular diet to avoid altering the expected outcome, a factor that increased the effectiveness of the study.
Interestingly, participants with lower body weight benefit more from carbohydrate ingestion than heavier players. Carbohydrates are immediately broken down into glucose, further broken down to produce energy in aerobic and anaerobic conditions. During the match, anaerobic metabolism occurs, leading to the conversion of glycogen stored in the muscles to produce glucose, which in turn produces lactic acid, leading to fatigue. According to studies, carbohydrate ingestion reduces the dependence on muscle glycogen by producing glucose, which, in return, lengthens fatigue time. For instance, Anderson et al. (2022) explain that a decrease in muscle glycogen triggers phosphorylation of activated protein kinase and p38 mitogen-activated protein kinase, leading to the entry of peroxisome proliferator-activator receptor gamma co-activator 1-alpha (PGC-1a) into the nucleus and mitochondrion. The presence of PGC-1a in the organelles activates transcription factors that increase the expression of mitochondrial proteins, affecting the electron transport chain (Anderson et al., 2022). Football performance is negatively affected under low carbohydrate availability due to increased intramuscular lipolysis of adipose tissue and adrenaline circulation. Other studies show that carbohydrate intake helps to improve football skills, which involve engaging and intense muscular movement. Football skills also involve using the brain, which works effectively under high glucose concentrations.
The timing of carbohydrate ingestion affects the level of effectiveness of players due to variations in energy demand. The timing affects the carbohydrates available to the muscles during the match. For instance, an intake of 25 grammes of carbohydrate per kilogram body weight three hours before the football match begins leads to an increase in muscle glycogen. Metabolically, ingested carbohydrates are immediately converted into glucose, which is oxidized to produce energy (Phillips et al., 2010). The energy demand is low three hours before the performance as the players are in relaxed mode. The pancreatic hormone insulin stimulates the conversion of excess glucose into glycogen, stored in the body’s muscles or fats (Noh et al., 2023).
On the other hand, ingesting carbohydrates for an hour or 30 minutes to the beginning of the match provides glucose, which is directly utilized in the body to produce energy. Carbohydrate ingestion during the half-break is essential as it provides the maintenance energy required for running, sprinting and executing football skills. According to Noh et al., 2023, the effectiveness of carbohydrate electrolytes varies with the time of intake, and the metabolic response is dependent on intensity and endurance of the exercise. The experimental study involved eight participants aged between 21.32 ± 1.19 years with a BMI below 24, representing real football match players. The participants ingested carbohydrate electrolytes at three different intervals: before the exercise, during half-time, and at both times. The results indicate that ingesting carbohydrates both at the beginning and during break-time lowered the respiratory exchange ratio and increased fat oxidation significantly compared to those who took it during half-time only. Tests on carbohydrate oxidation and heart rate did not differ significantly among the groups.
The role of carbohydrate ingestion varies based on the hydration strategy, as it affects muscle glycogen loading and energy availability. Some common hydration strategies utilized in football matches include a combination of beverages, supplementation and carbohydrate-electrolyte treatments. A controlled experimental study by Kingsley et al. (2014) showed that participants that took carbohydrate-electrolyte-caffeine had a high glucose concentration and sprint performance during the match. The blood glucose did not drop below the initial level despite the strategy used, although a variation in lactate concentration and mean heart rate were observed. High carbohydrates resulted in high plasma osmolality and sodium concentration, unlike normal carbohydrates and placebo. The common hydration strategy in commercial drinks involves fluid ingestion of about 400-800 millilitres per hour. The level of carbohydrate oxidation can be increased by 20-50 per cent by ingesting multiple forms during the exercise (Phillips et al., 2010). Multiple carbohydrates reduce barriers to adsorption in the lumen during vigorous body activities. Some forms include carbohydrate gels and higher carbohydrate supplementation, as they reduce fluid-based ingestion rates and potential intestinal discomfort. Caffeine supplementation improves adsorption and oxidation rates, increasing sprint performance, unlike the placebo (Yeo et al., 2005). However, increased abdominal discomforts were reported under high carbohydrate supplementation, higher heart rate, and lactate concentration (Kingsley et al., 2014). The study findings are inconclusive as all strategies have limitations; thus, there is a need for further research to establish the most effective carbohydrate-hydration strategy for football players.
Conclusion
Generally, carbohydrate intake positively impacts players’ performance in a football match both directly and indirectly. Directly, carbohydrates are converted into glucose, which is used as a source of energy. Indirectly, carbohydrate intake lengthens exhaustion time by reducing the utilization of muscle glycogen, thus reducing lactic acid production. The timing of carbohydrate intake affects its role in providing energy to players, and it is recommended to be taken after warm-up and during the fifteen-minute break. The most recommended nature of carbohydrates is gels or sports drinks which are easily broken down with fewer problems within the gastrointestinal system. Carbohydrate-electrolyte-caffeine is a recommended hydration strategy for football players as it increases oxidation levels. Although insights on the role of carbohydrate ingestion in football performance are studied, there is a need for further research to establish the most effective hydration strategy and timing.
References
Anderson, L., Drust, B., Close, G. L., & Morton, J. P. (2022). Physical loading in professional soccer players: Implications for contemporary guidelines to encompass carbohydrate periodization. Journal of Sports Sciences, 40(9), 1000-1019.
Goedecke, J. H., White, N. J., Chicktay, W., Mahomed, H., Durandt, J., & Lambert, M. I. (2013). The effect of carbohydrate ingestion on performance during a simulated soccer match. Nutrients, 5(12), 5193-5204.
Hills, S. P., & Russell, M. (2017). Carbohydrates for soccer: A focus on skilled actions and half-time practices. Nutrients, 10(1), 22.
Kingsley, M., Penas-Ruiz, C., Terry, C., & Russell, M. (2014). Effects of carbohydrate-hydration strategies on glucose metabolism, sprint performance and hydration during a soccer match simulation in recreational players. Journal of science and medicine in Sport, 17(2), 239-243.
Mizuno, S., Kojima, C., & Goto, K. (2016). Timing of carbohydrate ingestion did not affect inflammatory response and exercise performance during prolonged intermittent running. SpringerPlus, 5, 1-8.
Noh, K. W., Oh, J. H., & Park, S. (2023). Effects of the Timing of Carbohydrate Intake on Metabolism and Performance in Soccer Players. Nutrients, 15(16), 3610.
Phillips, S. M., Turner, A. P., Gray, S., Sanderson, M. F., & Sproule, J. (2010). Ingesting a 6% carbohydrate-electrolyte solution improves endurance capacity, but not sprint performance, during intermittent, high-intensity shuttle running in adolescent team games players aged 12–14 years. European Journal of Applied Physiology, 109, 811-821.
Yeo, S. E., Jentjens, R. L., Wallis, G. A., & Jeukendrup, A. E. (2005). Caffeine increases exogenous carbohydrate oxidation during exercise. Journal of Applied Physiology, 99(3), 844-850.
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