Traditional archery and heart rate: Zolkafi 2019

Thirty-four sedentary young men, aged 18 to 30 and doing less than 150 minutes a week of moderate or vigorous activity, were randomly split into two groups of 17: one did eight weeks of traditional archery, three sessions a week, while the other carried on as before. Heart rate variability (HRV) was recorded before and after, during a forced blowing test.

In the archery group the low-frequency component (LF) rose from 2,019.7 to 3,418.1 (p = 0.01) and the LF/HF ratio from 2.9 to 6.4 (p = 0.02); the high-frequency component (HF) and SDNN stayed practically the same (SDNN from 81.9 to 82.6 ms). In the control group no change was significant, although HF fell from 2,074.2 to 1,226.2 and the LF/HF ratio rose from 2.8 to 3.7. The authors read the rise in LF and in the LF/HF ratio as an improvement in heart function and suggest traditional archery as a first step into exercise for sedentary people.

The archery group used a 40-pound wooden barebow and fibre arrows, 10 metres from the target boss, with a qualified coach: 42 arrows per session in 6 sets, three sessions a week. The control group did nothing new. Participants had a mean BMI close to 29 (28.61 and 29.59 in the two groups) and about 33% body fat.

HRV was recorded with an Actiheart on the chest while the participant, seated and with a nose clip, blew into a mouthpiece connected to a sphygmomanometer, holding 40 mmHg for 15 seconds, twice, with a rest in between. Before and after were compared with a paired t-test within each group; there is no direct comparison between the groups.

The same 34 men appear to be the sample of a second paper by the same authors, on muscle strength after 12 weeks of archery: the ethics approval number is the same and the body composition values match. This paper would then report the eight-week measurement.

The weakest point is the interpretation. A higher LF/HF ratio is usually read as a shift towards sympathetic activity, not as a sign of a healthier heart, and the rise in LF points the same way; the authors call it an improvement without discussing the other reading. Moreover, the measurements come from 15 seconds of blowing against resistance, a manoeuvre that itself disturbs heart rhythm, whereas spectral indices need longer recordings at rest. LF and HF are given in Hz, which is not a unit of power.

The comparison between groups, the heart of a randomised trial, is missing: two separate tests, one significant and one not, do not show that the groups changed differently. Standard deviations are very large relative to the means, the randomisation method and any dropouts are not reported, and the paper is a five-page conference proceeding.

For archers, or for anyone thinking of offering archery to sedentary people, the study does not allow the claim that eight weeks of shooting improve heart health. It describes a programme of three sessions a week of 42 arrows with a 40-pound bow, offered to sedentary, overweight young men, and shows that some HRV indices, measured in a non-standard way, changed in a direction open to opposite readings. Anyone who uses HRV to follow their own training usually works with resting measurements and different indices, so the figures in this paper are not comparable with theirs.