Dehydration and archery scores: Savvides 2020 study

Ten Cypriot archers at national level shot the same competition simulation twice, once normally hydrated and once after twenty-four hours on restricted fluid. The score did not change: 550 points plus or minus 63 when hydrated, 562 plus or minus 59 when dehydrated, with p equal to 0.155, and no relationship between score and urine concentration.

Everything else changed. Urine specific gravity was 1.032 plus or minus 0.005 in the dehydrated trial against 1.015 plus or minus 0.004 in the other (p below 0.001), and sat above the 1.025 threshold for all ten archers. Thirst was far higher from the start (trial effect p below 0.001, partial eta squared 0.836), and so was perceived fatigue (p equal to 0.041, eta squared 0.388). Resting heart rate was 85 beats plus or minus 5 against 78 plus or minus 6.

The heart is the most interesting part, because you can see where it gives way. Over the first six ends the two trials were identical (p above 0.106); then, in the break after the sixth, the dehydrated heart rate stayed higher (p equal to 0.005), and it remained higher at the seventh end (p equal to 0.041), the ninth (0.043), the tenth (0.016) and the eleventh (0.034), with the same tendency at the eighth (0.086) and the twelfth (0.075).

The ability to concentrate, which the abstract reports as impaired, behaves more oddly in the results: it was lower at the start of the dehydrated trial (p equal to 0.009), but by the end the two trials were level (p equal to 0.320), because when dehydrated it held steady (p equal to 0.260) while when hydrated it fell (p below 0.001). Taken as a whole, the comparison between the two trials gives no difference at all (p equal to 0.244). Alertness showed nothing in either direction.

The participants were seven men and three women, aged 22 plus or minus 3, 171 centimetres plus or minus 9 tall and weighing 74.4 kilograms plus or minus 11.9, training five or six days a week for two or three hours a day and competing for at least two years in Division A of the national championship. The two trials were run in counterbalanced order, seven days apart, at the Cyprus Archery Federation's facilities during the competitive season: the warm-up began at 8.20 a.m. and the last arrow was away by 10.50, at 36 or 37 degrees and a relative humidity of 81 to 83%.

For the twenty-four hours before each trial all of them followed the same isoenergetic diet, 20% protein, 55% carbohydrate and 25% fat, which supplied about 1.2 litres of water from food and oxidation. Caffeine, supplements and alcohol were excluded for the preceding 48 hours. In the dehydrated condition fluid came as 250 millilitres at five points in the day, 1.25 litres in all; in the hydrated one, 500 millilitres at breakfast, lunch and dinner plus 250 at six other points, which is 3 litres. Hydration was checked on the first morning urine sample with a refractometer, with the threshold set at 1.025.

The warm-up was two sets of six arrows at 5 metres within four minutes with a three-minute break, then two ends of six arrows at 70 metres, then ten minutes' rest. The simulated competition followed international rules at the Olympic distance of 70 metres: ends of six arrows, four minutes each, three minutes to collect and score, a ten-minute break halfway, for a total of 72 arrows. No food or fluid was allowed during the trials.

A Polar H7 chest strap recorded heart rate continuously, read at baseline, at the end of the break after the sixth end and at the end of every end. Thirst, fatigue, alertness and the ability to concentrate were collected on a 0 to 10 visual analogue scale at the start and the end of each trial. The score was compared with a paired t-test, everything else with a two-way repeated-measures analysis of variance (time point by trial) and Bonferroni correction.

The sample is ten people, and the authors add two gaps: there are no blood markers of hydration and body mass was not measured during the trials, so the fluid loss is never quantified directly. They also acknowledge that urine specific gravity is not the reference measure, while arguing that values above 1.030 indicate a loss of more than 2% of body mass. And fluid restriction cannot be concealed from the person undergoing it: everyone knew which trial they were in, and thirst, fatigue and concentration are their own reports.

The description of the simulated competition does not add up: the methods describe six ends of six arrows, while the heart rate figures run to a twelfth end and the conclusions speak of 72 arrows. This record follows the 72. Two p-values in the abstract do not match the results: the abstract gives concentration a p of 0.016, which in the results is the baseline comparison for fatigue, and gives the resting heart rate difference a p of 0.021, which in the results is 0.003.

The point the authors raise themselves is the most relevant one: 72 arrows are about half of what a full competition day demands, somewhere near 140 arrows, and heart rate was still climbing when the trial ended. A difference that appears late had no time to appear here.

The conditions, finally, are those of a Cypriot morning in high summer: 36 or 37 degrees with more than 80% humidity. They say nothing about a cool day, nor about dehydration that develops during a competition rather than before it.

The figure to hold on to is this one: a day of restricted drinking, enough to show up clearly in the urine and raise resting heart rate by seven beats, did not change the score over 72 arrows at 70 metres. What it changed was how the archers felt and how the heart behaved in the second half of the session.

That does not mean drinking is unimportant. It means that over half a competition, in ten trained archers, what gave way was comfort and heart rate, not the arrows. And the point at which the heart gives way is specific: the first six ends are identical, the gap opens in the mid-session break and stays open through the second half. Over a full day, with twice as many arrows, the authors leave the question open.

For anyone watching heart rate on a watch during competition, there is a second useful element: the same arrows, shot by the same archers, gave the same score with a seven-beat difference in resting rate. A higher heart rate, in this case, did not cost points.

The part about concentration deserves a note of its own, because it is the part that circulates most and the part the paper supports least: the sense of being able to concentrate started lower when dehydrated, but ended level, because when hydrated it declined over the course of the session while when dehydrated it was already low and did not decline. This study does not show that dehydration costs an archer clarity during a session.