Energy intake and expenditure in archers: Singh 2016

The study compares how much twenty male Indian university students eat and spend, aged 17 to 25 and all having competed at least at inter-university level: half of them archers, half middle-distance runners. For seven days each one filled in a record of everything eaten and drunk, with amounts, and a record of every activity in the day, from walking to running to exercise.

The archers report an average intake of 3,732.8 kcal a day against 5,118.1 for the runners, and an estimated expenditure of 3,390.6 kcal a day against 5,462.6. Both comparisons are declared significant, with t values of 84.16 for intake and 112.9 for expenditure.

The author's reading is straightforward: distance running lasts a long time, burns more and calls for a higher intake, while in archery the exercise is short and of low intensity, so less energy is needed. It is worth noting that in the archers the reported intake exceeds the estimated expenditure by about 340 kcal a day, while in the runners expenditure exceeds intake by about 345 kcal: a positive balance in the first group and a negative one in the second, which the paper records without comment. Of diet composition, body mass, stature and any other measurement of the athletes there is no trace.

The design is cross-sectional and descriptive. Twenty male athletes, ten per group, were given two records to fill in for seven consecutive days: one for everything they took in, with amounts, and one for every activity carried out during the day. Calories were derived from a database of about fifty commonly used Indian recipes, built by the author; expenditure was calculated from the recorded activities. The daily totals for intake and expenditure were summed over the seven days to give the figures in kcal per day.

Selection is defined by delimitations rather than inclusion criteria: men only, athletes who had reached at least inter-university level, aged 17 to 25, twenty participants in all. The author states that analysis of variance and t-tests were used; the results contain two t-tests only, one on intake and one on expenditure.

The detail that changes how everything else reads sits in the tables: the number of observations per group is 70, and a footnote specifies that observations are the number of days multiplied by the number of participants. Seven days times ten athletes is exactly seventy. The means and standard deviations are therefore computed on person-days treated as independent units, and the t-tests compare 70 days against 70 days rather than ten athletes against ten.

The statistical analysis does not hold up. Treating 70 person-days as independent observations inflates the apparent precision: that, rather than any enormous difference between people, is what produces t values of 84 and 113, numbers with no interpretable meaning in a study of twenty athletes. The standard deviations point the same way, at 95 to 119 kcal a day: free-living intake across ten people and seven days varies far more than that, and a spread this small suggests either that the records were filled in uniformly or that the calculation was done on means rather than on individual days.

The data needed to use the numbers are missing. Body mass and stature are not reported, so the calories cannot be converted into grams per kilogram or compared with the recommendations, which are all expressed per kilogram of body mass. There is no description of how the recorded activities were turned into calories, no validation of the diary, no statement that anyone checked it, and the food diary method tends by its nature to under-report. Neither ethical approval nor consent is mentioned.

Finally the text contradicts itself. The discussion announces a comparison between judo athletes, yoga practitioners, archers and middle-distance runners, groups that do not exist in this paper, so the work reads as an extract from a larger thesis with two rows of a table lifted out of it. The journal header gives 2015 while the issue is dated 2016. In this registry the venue is flagged as having questionable editorial standards, and this record should be read with that notice in front of it.

What an archer can take away is only an order of magnitude, and even that with care: ten young Indian university archers in training reported around 3,700 kcal a day, with an estimated expenditure around 3,400. These figures sit in the same range as those other studies estimate for elite archers in competition, which is one way of saying that archery, for all its reputation as a static sport, does not come cheap when training runs for hours.

The comparison with the runners is the paper's point and is of no use to an archer: it says only that running a long way costs more, which needs no study. There is nothing on diet composition, nothing on body mass, and therefore no way of deriving an individual requirement from these numbers. Above all there is no measurement of shooting: no score, no arrow count, no relationship between what these archers ate and what they did on the target. In this registry the source documents that the question of energy balance in archery was raised early and with fragile means, rather than establishing a figure.