Effects of cold strain on simulated sentry duty and marksmanship.

BACKGROUND

Cold exposure is not uncommon to military situations, but its effects on dismounted soldier performance are not entirely known. The present study was conducted to determine the level of cold strain that would degrade the detection, identification, and engagement of targets.

HYPOTHESIS

Degradation in marksmanship, but not vigilance, is expected in individuals that reach significant levels of cold strain, short of uncontrollable shivering.

METHODS

There were 12 active duty male soldiers (mean +/- SD of 28.1 +/- 5.5 yr, 178 +/- 60 cm, and 87.8 +/- 18.1 kg) who participated in 2 counterbalanced trials involving cold (COLD) and thermal-neutrality that served as control (CNTL). Subjects were exposed to a local cold air temperature of 0 degrees C while wearing a tube suit through which 5 degrees C water circulated during COLD. Measures of marksmanship were taken during three 15-min sessions involving simulated hostile target engagements using a rifle and measures of vigilance were taken during two 1-h sessions involving simulated sentry duty.

RESULTS

All physiological measures and subjective indices indicated that significant cold strain was attained during COLD (mean finger and core temperatures reached 10.8 and 36.3 degrees C by the end of the 165-min exposure) compared with CNTL. The number of target engagements decreased while relative hit accuracy increased during the cold condition, and vigilance was unaffected.

CONCLUSIONS

Significant cold strain, short of uncontrollable shivering, adversely affected the subjects' response to targets, but not their marksmanship and vigilance, at least for a period of time not exceeding 3 h in a controlled environment.