Heart and lungs in young archers: Eswaramoorthi 2018

Thirty-two young Malaysian archers had a set of resting heart and breathing measurements taken and then shot one end of 6 arrows at 50 metres. There were twelve measurements: heart rate, systolic and diastolic blood pressure, breathing rate and eight lung volumes and flows recorded with a spirometer. Using principal component analysis the authors reduced them to four groups, which together account for 76.4% of the variability in the data. The first brings together forced vital capacity, maximum voluntary ventilation and peak expiratory flow (loadings between 0.84 and 0.88), the second the two resting blood pressures, the third inspiratory reserve volume (0.86) and the fourth resting breathing rate (0.88). Heart rate, expiratory reserve volume, inspiratory capacity, vital capacity and tidal volume stay below the 0.75 threshold the authors chose.

A second analysis split the archers into two groups: 27 with higher lung values and 5 with lower ones. A discriminant analysis then reassigned the archers to these groups with an accuracy of 90.63%, 93.75% and 96.88% using four variables, three variables and a single one (peak expiratory flow, in the last case). In a profile chart the group of 27 also sits higher on shooting score.

From this the authors conclude that good lung capacity, an adequate breathing rate and optimal resting blood pressure are needed to shoot better. The paper, however, contains no correlation or regression between the physiological measures and the score, and the scores of individual archers or of the two groups are never given as numbers.

The design is cross-sectional, which the authors call ex post facto. The participants were 32 archers from the Terengganu sports council in Malaysia, non-smokers with no musculoskeletal, cardiorespiratory or neurological disorders: 24 males and 8 females aged 13 to 24, with a mean age of 17.0. Bow type, level, years of shooting and target face size are not reported.

Heart rate and blood pressure were taken seated with an Omron HEM-7120 automatic monitor on the left arm. Lung volumes and flows were measured with a Cosmed Pony FX digital spirometer, again seated and with a nose clip: for forced vital capacity and peak flow, a few normal breaths followed by a deep breath in and a forced breath out held for 6 seconds; for maximum voluntary ventilation, 12 seconds of breathing as deeply and quickly as possible. Each test was repeated three times and the average used. Resting breathing rate was counted by a therapist with their hands on the chest for one minute, timed with a stopwatch.

After the measurements the archers shot in a simulated competition: 4 practice arrows and then 6 scoring arrows at 50 metres, a single end. The analyses are principal component analysis with varimax rotation, hierarchical cluster analysis and discriminant analysis in three modes, run in GraphPad Prism 4.03 and XLSTAT 2014.

The score comes from 6 arrows at 50 metres, too few to separate archers who are close in ability: two different ends from the same archer can differ by more than the two groups. The analyses used describe how the physiological measures group together, not how they relate to shooting. The discriminant analysis accuracy of over 90% proves nothing: the two groups were built from the same variables that are then used to recognise them, and with 27 archers against 5, simply putting everyone in the larger group would already give 84%.

Some figures do not add up. A mean age of 17.0 with a standard deviation of 0.56 cannot fit a range of 13 to 24; forced vital capacity is reported in millilitres per kilo, but the values, from 2.07 to 5.19, look like litres; the loadings of the two blood pressures are swapped between the table and the text; and in the discussion the cumulative percentages of variance are read as the contribution of each group. The sampling adequacy measure is 0.53, which is low, with 32 people for twelve variables.

Lung volumes depend on height, sex and age, and in a group aged 13 to 24 with boys and girls together, those differences alone can produce "high" and "low" groups that have nothing to do with shooting. The statements about autonomic balance and anxiety are interpretation: nothing of the kind was measured.

For anyone who shoots, the study changes nothing. It does not show that training lung capacity raises scores, nor that archers with more breath shoot better: it shows that in 32 young Malaysian archers the breathing measures go together, and that a small group with lower values also sits lower on a chart that includes six competition arrows.

Breathing does matter in archery, but for a different reason: how it is managed during the draw and the aim to keep the body still. That is a different thing from the litres someone blows into a spirometer at rest, and the paper has no data on it. Where it is cited in support of breathing exercises or breathing devices, the link with score was not measured here.