MARKSMANSHIP IS IMPAIRED AT ALTITUDES BEYOND 3,000 m
Swain, D. P., Moore, C. M., Ringleb, S. I., & Morrison, S. (2013). The effects of acute hypoxia on marksmanship. Medicine & Science in Sports & Exercise, 45(5), Supplement abstract number 2713.
This study evaluated the effects of acute hypoxia and physical exertion on marksmanship, a significant question for the military. At each of five simulated altitudes (162 m, 1,015 m, 2,146 m, 3,085 m, and 3,962 m), Ss performed four shooting trials: at rest, immediately after a 60-second run with load, and twice more following 30-second rest periods. Arterial oxygen saturation (SaO2), heart rate, and ventilation rate were recorded.
Increased altitude significantly decreased marksmanship. Shooting scores at 3,962 m were significantly lower than those at all other altitudes. Shooting score at rest was ~5.6% less at 3,962 m than at sea-level. The exercise task decreased shooting performance. Decreased shooting scores partially improved during recovery. The shooting score at rest was significantly greater than in all trials following exercise, decreasing ~3.8% immediately post-exercise at sea-level, and decreasing ~6.0% immediately post-exercise at 3,962 m. Altitude and exercise both significantly reduced SaO2 and increased ventilation rate. Heart rate did not change with altitude, but increased following exercise. There was a strong positive correlation (r = 0.84) between marksmanship and SaO2; a strong inverse correlation (r = -0.72) between marksmanship and ventilation rate; and a modest inverse correlation (r = -0.54) between marksmanship and heart rate.
Implication. Increasing altitude impairs marksmanship, with a threshold at approximately 3,000 m. Decreased marksmanship was closely related to decreased arterial oxygen saturation, which could impair cognition and increase ventilation, the latter impairing aim by increasing movement of the chest wall.
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