Energy, hydration and sleep in archers: Esen 2024

Six male recurve archers from the Turkish national team were followed through the four days of a European Grand Prix in April 2023. Three were Olympians or World and European medallists, three were international-level athletes; on average they were 20 years old, 67.5 kg in body mass and 180.3 cm tall, and they trained twelve archery sessions of two and a half hours plus six strength sessions a week.

The load of the four days varied widely: 180 arrows and 335 minutes on the field on day one, with 4,200 metres walked, then 38 arrows and 27 minutes on day two, 162 arrows and 212 minutes on day three, 72 arrows and 113 minutes on day four. Estimated energy expenditure followed the same pattern, from 4,067 kcal on day one to 2,527 on day two. What they ate changed with the load as well: 3,985 kcal on day one, 2,564 on day two, 3,315 on day three, 2,847 on day four, which is 60 down to 38 kcal per kilogram of body mass. Carbohydrate went from 7.1 g per kilogram on the fullest day to 4.0 on the lightest, protein from 3.6 to 2.2, and fat sat between 24 and 36% of calories. Day one was higher than all the others for energy and carbohydrate (p < 0.001 for energy).

Urine specific gravity was read four times a day. The 24-hour means stayed below 1.020, the threshold the authors use to call an athlete euhydrated, but on waking the values were higher than before competition (p = 0.004) and than after it (p = 0.046), and before bed they were higher than after competition (p = 0.007): in the morning these archers sat just above that threshold, that is slightly short of being fully hydrated, and recovered before shooting. Sleep recorded with a wrist accelerometer ranged from 465 to 529 minutes a night, with 6 to 9 minutes to fall asleep and 2 to 5 minutes awake after sleep onset, with no differences between days. Self-reported sleepiness on waking, by contrast, stayed high, at 8 or 9 on a scale that runs to 10.

Measurements were taken in competition, on a grass field, at a mean 14.5 °C, 47% humidity and wind around 6.5 miles per hour. Archers are not allowed any electronic device during competition, so arrows, duration and metres walked were counted by hand by the observing researcher: duration runs from the official start time to the end of that archer's day, including the waiting between ends, and the distance comes from the roughly 140 metres covered walking to each end shot at 70 metres. Energy expenditure was not measured: it is estimated from resting metabolic rate with the Harris and Benedict equation and from the metabolic equivalents of the activities.

Food was recorded with a diary, a method the archers were already used to, and every meal was photographed by the researcher to check portion sizes and recover anything the diary had missed; the analysis was run with Nutritics software. Breakfast and dinner were at the team hotel and lunch at the competition ground, with set menus designed by a nutritionist following the Athlete's Plate tool, and each archer served themselves freely, with no obligation to finish. Hydration was assessed on urine collected on waking, about 30 minutes before competition, about 15 minutes after the end, and 30 to 60 minutes before bed, read with a handheld digital refractometer and accompanied by a urine colour chart. Sleep was captured three ways: a standardised sleep diary, the Karolinska Sleepiness Scale completed 30 minutes after waking, and a wrist accelerometer worn from the evening, sampled at 10 Hz and analysed in 60-second epochs, with a button pressed when the archer began trying to sleep and on final waking.

Six archers from a single team, at a single event, with no comparison group: this record describes what those six did, not what an archer needs. Both sides of the energy balance are weak. Expenditure is a calculation rather than a measurement, and the authors themselves write that the metabolic demand of an archery event remains to be studied; intake comes from food diaries, a method that tends to under-report, although the meal photographs help here. The diet was set by a nutritionist and served from a fixed menu, so what can be seen is a plan being carried out rather than a spontaneous choice.

The load of the four days was not set by the researchers: it depended on how far each archer went in the head-to-head matches, and the authors acknowledge this. That weakens the reading in which the archers adjusted their carbohydrate to the expected load, because the bracket partly moves load and appetite together. Not one arrow was scored for the research: the study links nothing to performance. The high sleepiness ratings on waking are left unexplained, because sleep structure was not recorded, and both the diary and the scale are the athlete's own reports. Urine specific gravity has well-described limits, which the authors cite, and at 14.5 °C on the field sweat and electrolyte losses were not measured. Two numerical details do not match across the paper: the summary gives a range of 2,563 and 3,986 kcal where the table says 2,564 and 3,985, and the same summary reports the between-day comparison as p > 0.01 while the results give p < 0.001.

The study puts numbers on what a four-day international costs. On the heaviest day these archers shot 180 arrows, spent five and a half hours on the field and walked more than four kilometres, with an estimated expenditure around 4,000 kcal; on the elimination days the load collapsed, down to 38 arrows and less than half an hour. Anyone planning a trip can take that as an order of magnitude, bearing in mind that the duration depends on how far the archer progresses.

What they ate followed the load, and the carbohydrate figures sit inside the general recommendations for athletes, while protein exceeded them on the two full days. The question that matters to an archer, whether eating this way changes the score, is outside what the study can answer: no score was collected, and six archers would not be enough in any case. On hydration the most concrete finding is about timing: the only point in the day when these archers crossed the threshold, and only just, was on waking, while before competition, after it and in the evening they were fine. Sleep was consistent in duration, from seven and three quarter hours to almost nine, yet on waking they reported feeling very sleepy, and the study does not try to resolve that gap between the accelerometer and the sensation.