Macronutrient Intake in Team Sport Athletes

Introduction:

Optimizing energy intake and macronutrient composition is crucial for enhancing performance and supporting the training demands of team sport athletes. Inadequate energy intake during training can lead to adverse effects such as loss of lean muscle mass and decreased bone density, increasing the risk of injury. Unfortunately, studies have shown that many team sport athletes lack proper knowledge regarding their dietary requirements, resulting in suboptimal nutrition practices.

Energy Requirements of team sport athletes:

Consuming the required amount of energy optimises an athletes performance and improves on their training. A diet that lacks in energy during training can result in loss of lean muscle mass and bone density. Athletes that consume less energy than required run the risk of injury (Kerksick 2018). Studies were carried out by (Tooley et al 2015) and (Jenner et al 2018) based on rugby and football players, they used a DEXA scanner to assess body composition. During research it was said players lacked knowledge when looking at their food diaries. Looking at the literature it is clear that male team athletes are eating less and not meeting the requirements. Research carried out by (Bradley et al 2015) found that rugby players during preseason do not meet energy requirements recommendations which is (14.8 ± 1.9 MJday). Another study by (Andrews et al 2016) observed that semi and professional footballers underreported their dietary intakes as they wanted to maintain or reduce body fat (11.5 ± 2.0 and 10.8 ± 3.8 MJday).

Carbohydrate Intake of team sports athletes:

Team sport athletes need to consume a sufficient amount of carbohydrates to improve performance and help with recovery after training and matches. Team sports are completely unique as they require different levels of intensity in training. Current literature suggests that team sport athletes consume low carbohydrate diets that do not meet the recommendations (Burke et al 2011). It is recommended that team sport athletes should be consuming 6-10gkg of bodyweight per day depending on their gender, level of fitness and energy expenditure (Hassapidou 2011). The role of carbohydrates is to restore muscles and liver glycogen between training sessions and matches. In this review the research states that all the team sport athletes are eating lower amounts of carbohydrates than required.

In a recent study dietary intake was assessed in female ice hockey players over a 7 day period including practice, rest days and game days focusing specifically on their carbohydrate intake (Vermulen et al 2021). 23 players volunteered and the overall conclusion states that their diet was 52% carbohydrates and this is below carbohydrate recommendations. An athletes diet should consist of approximately 65% carbohydrates. During the study Vermeulen observed that the players consumed more carbohydrates on game days and less on restpractice days. Overall these female athletes would benefit by increasing their carbohydrate intakes. This study was completed on a very small group which can make it difficult to determine if the finding is accurate. The likelihood of biased results and error are very high in this study. In another study carried out by (Steffl 2019) he focused on macronutrient intake especially carbohydrates in junior and senior soccer players. Within this study there were 647 junior players (mean age 10.0-19.3) and 277 senior players (mean age 20.7-27.1). The carbohydrate intake was below average in both groups (5.7 95% CI 5.5-5.9 kg/day in junior and 4.7 95% CI 4.3-5.0 kg/day in senior players). Adequate carbohydrate intake is important in recovery and improving performance. Carbohydrates play an important role in muscle glycogen resynthesis. Players can get fatigue during long matches due to the lack of muscle glycogen and this is why consuming the correct amount of carbohydrates is vital. This study was more reliable than Vermeulen as there was a bigger sample. There were a few limitations such as the information was only collected on certain days such as rest days, training days etc. In this particular study it wasn’t divided into sub elite and elite athletes which means it would be hard to compare as the professional soccer plays have nutritionists who can guide them with their diets.

Protein Intake of team sports athletes:

Athletes need more protein than a normal individual as they are building and repairing muscle and connective tissue (Best 2020). Depending on the type of sport an athlete plays determines their protein intake. Rugby is a high impact sport and match time is 80 minutes. Rugby consists of high intensity exercise such as sprinting and tackling and is of a aerobic nature (Roberts et al 2008). Athletes who consume less protein than required have a bigger risk of muscle wasting and injury. Protein recommendations from ISSN suggest athletes should consume 1.4-2.0gkg per day (Kerksick et al 2018). Looking into the literature it states that most athletes are consuming the recommended amount of protein required and many are consuming a lot more than necessary. High protein diets are beneficial for athletes who want to maintain lean muscle tissue.

Research suggests that a diet high in protein (2.3-3.1kgday) may be good for athletes that want to be lean but reduce fat mass (Jager et al 2017). This statement is support by Bradley et al (2015). A study carried out by Potgieter reported that rugby athletes intake during in-season exceeded protein requirements, they were consuming (1.2 (0.6) gkg BW). Research by (Mackenzie et al 2015) suggests evidence that increasing protein intake may be desirable to promote muscle synthesis however there is a limited benefit for overconsuming as extra protein may be lost when oxidation occurs. The study by Mackenzie et al measured daily protein intake and protein distribution in 25 elite rugby athletes 20.5 ± 2.3 years old, weightheight (100.2 ± 13.3 kg, 184.4 ± 7.4 cm). The athletes were assessed at the start and end of preseason. The athletes used a 7 day food diary and they reported their protein intake was 2.2 ± 0.7 gkgday which exceeds daily recommendations. The athletes were consuming more than 20g of protein; 3.8 ± 0.9 times per day. It is currently unclear due to the lack of research carried out on team sport athletes if overconsuming protein will be beneficial. High protein diets could lead to lower energy diets. This study used a small number of rugby athletes which could affect the reliability and lead to bias. To improve on further studies there should be more participants recruited to improve the validity. Another study carried out by (Hoffman 2006) was based on college football athletes, it consisted of 23 male athletes. The participants all completed 12 weeks resistance training, 4 days per week and were supervised by the research panel. All participants also had to complete a 3 day food diary each week. From this study they recognised all athletes were meeting protein requirements. This study was carried out on a small group therefore to improve the literature in this area they should have more participants. Another limitation is the 3 day food diary, to get a better insight into the diets they should of tried to get at least 5 days including weekends to see if their diet habits change (Yang et al 2010). Overall this study wasn’t reliable.

Fat Intake of team sports athletes:

Fat is an important macronutrient for athletes to consume as part of their diet as it provides the body with essential fatty acids. Athletes need to consume essential fatty acids such as polyunsaturated fatty acids. The recommended fat intake for athletes is approximately 30% of their calorie intake (Elizondo et al 2015). For athletes that plan on decreasing their body fat it is recommended they consume 0.51gkgday of fat (Broad 2008). In a study carried out by (Horvath et al 2013) it looked at effects of varying dietary fat on the nutrient intake of male and female runners. The diets were split into low, medium and high fat and were designed for each participant based on their preference and the diets were eating for 28-31 days. The study consisted of 12 males and 13 female runners who run approximately 42miles per week. The results as per energy intake (% energy) averaged 17% energy for low fat diet, 31% energy for medium and 44% energy for high. The overall study concluded that runners are not consuming enough calories on a low fat diet and low fat diets decrease zinc intake and could have a bad impact on health and performance. This study was beneficial as it focused on both male and female participants but it could be improved by researching different types of athletes as well as recruiting a bigger number of participants. Another study carried out by (Zapolska et al 2014) assessed the nutrition of professional volleyball players. The study consisted of 17 women and the research tools used was a 24 hour recall and a survey. The use of a 24 hour recall is not as accurate as a 5 day food diary as people may forget to add specific details of everything they consumed. Another disadvantage of a 24 hour recall is people may eat in a certain way that isn't natural for them which could result in bias results. The results show that the diet of women volleyball players were low in energy but had an excessive proportion of saturated fatty acids and cholesterol but a lower content of mono and poly fatty acids. In another study it looked at the dietary intakes of American football athletes and it was found that they consume high fat intakes (41%E) (Kirwan et al 2012) and when comparing this study to Bradley et al 2015 based on rugby athletes their fat intakes were just above recommendations (35%-36%). When comparing studies in rugby athletes it is clear a reduction of dietary fat is needed and an increase in carbohydrates, this would help athletes meet energy requirements.

Most studies in the literature of team sport athletes consumed dietary fats over the recommendations. In a study by (Raizel et al 2017) stated that football athletes consume a high protein diet which can impact on high cholesterol. Research states diets high in saturated fats and cholesterol are linked to diseases such as CVD.

Conclusion:

In conclusion, all team sports are unique and some require more macronutrients than others depending on the position of players and how intense the sport is. There is very little research on the dietary intake of team sport athletes which makes it difficult to compare or draw firm conclusions. From the studies reviewed team sport athletes carbohydrate intake is below recommendations and most team sports athletes over consume protein and fat recommendations. More research into sports recommendations for macronutrients especially in carbohydrates and fat would be useful as athletes have different dietary needs compared to a non-athletes. Team sports athletes not eating the recommended macronutrients could be due to a lack of nutritional knowledge. In the future further research should be carried out to explore why the athletes choose to eat more protein than they do carbohydrates and see what influences their dietary intake.