Polish footballers short on carbs, critical nutrients, study finds

By Hank Schultz

- Last updated on GMT

©Getty Images - alphaspirit
©Getty Images - alphaspirit

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A recent study done on professional soccer players in Poland concluded that the players were not consuming enough carbohydrate and were deficient in several important nutrients. But an expert cited some flaws in the study’s design, highlighting the difficulty of real world sports nutrition research.

The study was published in the International Journal of Environmental Research and Public Health​. The researchers were associated with the University School of Physical Education, Wrocław, Poland.

Players followed during heavy training week

The researchers looked at the dietary intake of 26 professional soccer players from one club competing in Poland’s top league. The players were followed through a week of heavy training in preparation for the start of regular league competition. Some athletes with injuries and others who submitted incomplete dietary questionnaires.

The week’s training sessions including a couple of high demand days and some days of lesser intensity as well as a day off.  Some of the players were consuming supplements, while others apparently weren’t.  The researchers characterized supplementation as “food supplements and foodstuffs intended for particular nutritional uses.”

The athletes’ food and nutrient intakes were measured via detailed food questionnaires.  The amounts of food consumed was measured via standard household measures, and information from product labels was included where available.

Players short on calories with too few carbs

The study found the players on the Polish team consumed on average 2,655 kcal of food energy per day.  This is less than what similar studies had found for professional footballers in the Netherlands and Greece.  In both of those cases pro soccer players were consuming in excess of about 3,300 kcal a day.

As well as appearing to be short on calories in general, the researchers said the soccer players appeared to be short on carbohydrates in particular. Carbohydrates have been demonized to some degree by recent diet fads, and professional footballers are often concerned about their weight, as power-to-weight ratio figures directly into their endurance and their ability to accelerate. But the researchers noted that sufficient carbohydrate is crucial to quickly replenish glycogen stores in muscles. 

“The comparison of the obtained results with the norms showed that supplementation did not suffice to cover the recommended intake for the sportsmen training daily for more than 1 hour . . . Low carbohydrate availability can lead to muscle glycogen depletion and subsequent fatigue, impaired concentration, and decreased physical output,”​ they noted.

“The football players’ dietary carbohydrate intake was relatively low in comparison to requirements based on training loads. Based on our results we conclude that further work is necessary to reinforce education in this area in order to enhance athletic performance by the optimization of glycogen storage and resynthesis. Moreover, sports nutritionists working with elite football teams need to use an individualized approach when periodizing an athlete’s carbohydrate intake to support athletes’ training and match daily nutrition goals,” ​they concluded.

They also noted that the average consumption of vitamin B2, vitamin C, vitamin E, folate, and calcium was lower than recommendations.

Nutritionist says real world can make a mess of research goals

Lloyd Parker, head of nutrition for Everton Football Club in the English Premier League, said he was unsure whether the insights of the Polish researchers were actionable for a professional like him. Parker said in his own experience in reforming how Everton fed its players made plain to him how difficult measuring nutrient intake is in a real world setting.

“There are certainly some methodological flaws in how they have measured certain parameters but also some of the parameters they are trying to measure are highly complicated and virtually impossible in an applied setting. For example they mention some micronutrients (Vitamin B, C, E & folate), for you to get an accurate intake of these is extremely difficult,”​ Parker told NutraIngredients-USA.

“To start with you need a very accurate dietary intake record — which doing in a squad this size is hard and the method they have used is littered with errors — and then even with this, it is essentially a guess what the level of micronutrients within the foods they have eaten is. Unfortunately this depends on where the food is grown, soil composition, how it is harvested and then how it is cooked, all of which may affect the composition of the food, how its digested and what micronutrients are bioavailable to the body,”​ he added.

Timing of nutrient intake is difficult

Parker said for his players he shoots for 3,000 to 3,500 kcal of energy intake.  He said even with the changes he has made at Everton — supplying fresh whole foods instead of packaged supermarket sandwiches, for example — more still needs to be done to fine tune nutrient delivery, such as getting the ideal amount of carbohydrates into the players at the right times. But real life is messy, and players aren’t vehicles with easily filled and measured fuel tanks.

“Ideally, again depending on the session we aim for between 3-5k/kg/BM per day (of carbohydrate) on training days and then higher amounts (5-8g/kg/BM) on game days, but again not many players seem to get much above 6 g in my experience. I certainly feel that with higher intakes that energy levels could be improved in the latter stages of games, but this is very difficult to measure,”​ Parker said.

Source:International Journal of Environmental Research and Public Health
2020, 17​(22), 8567; https://doi.org/10.3390/ijerph17228567
Assessment of the Dietary Intake of High-Rank Professional Male Football Players during a Preseason Training Week
Authors: Ksiażek A, et al.

2021 Sports Nutrition Summit

Parker was a participant in NutraIngredients-USA’s 2020 Sports Nutrition Summit USA held in San Diego in January.  This coming year’s virtual event kicks off with a session on Thursday, Jan. 28, 2021​, with three more sessions to follow at one week intervals.  Stay tuned to NutraIngredients-USA for more details on this FREE event.

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