To the Editor: Controlled breathing is a fundamental principle of marksmanship. I describe an effect of viral lower respiratory tract infection on small arms training that was unexpectedly prolonged.

The patient (myself) had abrupt onset of respiratory infection, 1 day after a marksmanship training session on an electronic firing range. During the session, I obtained satisfactory scores from several firing positions (best score, 66 mm grouping for five shots and 126 mm grouping for 20 shots, at 200 m, prone firing position). The illness progressed rapidly from a non-specific prodrome to a flu-like illness with fever, malaise, muscle aches, lethargy, slowed cognition, cough, sore throat, rhinorrhoea, persistent lacrimation and a 24-hour period of prostration. Recovery began after 48 hours, allowing a return to light work at 72 hours and full working duties by Day 7.

On Day 14, during another marksmanship training session, my accuracy was severely decreased. I failed to obtain satisfactory scores in any position because of persistent erratic breathing and occasional involuntary coughing (best score, 235 mm grouping for 20 shots at 200 m). Spirometry later that day showed a reduced peak flow rate (310 L/min) (see Box). Serological tests were negative for IgG and IgA for all respiratory agents assessed. Nasal swabs were positive for parainfluenza virus type 3 by polymerase chain reaction testing.

Involuntary coughing, particularly towards the end of the day, and decreased exercise tolerance persisted for a further 2 weeks, by which time peak flow had increased to 500 L/min. A third marksmanship session the week afterwards showed an improvement in scores, but they were still worse than those obtained pre-infection. Notably, grouping deteriorated rapidly after the first series of 20 shots, and could not be regained even after short rests. Replay of the recorded laser beam pattern for the session indicated that the breathing pattern remained erratic, although peak flow had risen further to 550 L/min.

In the aftermath of the First World War, the joint head of Germany’s forces, Ludendorff, claimed that the failure of his 1918 spring offensive was ultimately caused by epidemic influenza.1 The epidemic affected German troops later than the allied forces, in June 1918. By July 1918, there were an estimated 500 000 German influenza casualties. Ludendorff’s initial successes were a result of new, highly mobile type infantry tactics — the forerunner of today’s “fire and movement” — which require physical fitness, stealth and accuracy of rifle fire.

My case demonstrates that the tactical consequences of a viral lower respiratory infection can last much longer than medically explicit morbidity. Prolonged effects in my case included persistent involuntary cough, loss of exercise tolerance and loss of marksmanship, weeks after the initial acute illness. Ludendorff’s claim may be not so far off the mark.

Marksmanship scores* and peak flow rates over time after onset of a respiratory tract infection

* Lower scores for shot grouping indicate better marksmanship (shots are more closely grouped).