Relaxation and EEG in female archers: Nam 2014 study

Thirteen Korean university archers, all women who had finished at least third at the national university championships and had on average 11.21 years of shooting behind them, practised Jacobson's progressive muscle relaxation for 12 weeks, three times a week for 15 to 20 minutes. Before and after, the researchers recorded resting EEG, blood pressure and heart rate.

Relative alpha power rose at four of the eight recording sites: left frontopolar (Fp1, from 0.36 to 0.39), left and right frontal (F3, from 0.38 to 0.39; F4, from 0.37 to 0.39) and left temporal (T3, from 0.45 to 0.47), all with p = 0.04. At the other four sites alpha did not change significantly, and relative beta power did not change at any site. Diastolic pressure fell from 69.83 to 67.5 mmHg (p = 0.03); systolic pressure (from 116.66 to 113.00 mmHg, p = 0.82) and heart rate (from 73.83 to 69.66 beats per minute, p = 0.18) did not change significantly. The authors conclude that the relaxation had a positive effect on the athletes.

The athletes came from two universities in the same metropolitan city, were 21.45 years old on average and were tested in 2013. The relaxation followed an audio recording, played to the group at 10 in the morning in a quiet, dimly lit room: a muscle group is tensed for 5 to 7 seconds, then released as fully as possible while attending to the feeling of relaxation. The Korean title speaks of physical relaxation through breathing, but the procedure described is the tensing and releasing of muscles.

EEG (PolyG-I, Laxtha) was recorded for one minute at rest with the eyes closed, at eight electrodes (Fp1, Fp2, F3, F4, T3, T4, P3, P4), filtered between 0.5 and 50 Hz; relative power is the power in one band divided by total power. Blood pressure and heart rate were taken seated with an automatic upper-arm monitor (Omron HEM-7210). The measurements were made at 10 in the morning, before and after the 12 weeks, and compared with paired t tests, one site at a time.

These are thirteen athletes with no control group: over three months blood pressure, heart rate and the resting EEG can change with the season, the training load or simply getting used to being measured. The alpha differences are two or three hundredths on values around 0.4, with p at exactly 0.04 at all four sites, and the eight comparisons are made without correction for multiple testing, so the result is fragile. The recording, moreover, lasted one minute.

There are also errors in the write-up. The paper defines the alpha band as 0.5 to 3.99 Hz, which is the delta band, and it is not clear which band was used in practice; the heart rate criterion for starting the recording is given once as 65 to 75 and once as 70 to 80 beats; some beta standard deviations are larger than the means (0.21 ± 0.43). The authors read the fall in blood pressure as an increase in pulse pressure, but on their own figures the gap between systolic and diastolic narrows, from 46.83 to 45.5 mmHg. None of the measures concerns shooting, either performance or the athletes' state in competition.

The study does not show whether progressive relaxation helps anyone shoot better: the measurements were taken at rest, away from the range, and scores were not recorded. What it does show is that after three months of regular practice, in a small group of experienced women archers, the resting EEG had slightly more alpha activity at some sites and diastolic pressure had fallen by just over 2 mmHg, with no comparison group to tell how much of this is due to the relaxation.

For anyone already using Jacobson's relaxation, the study describes a simple routine, a 15 to 20-minute recording three times a week, that good-level athletes kept up for twelve weeks. What it changes on the shooting line remains to be shown.