Exhaustive Whole Body Exercise And Torso Loading Degrades Markmanship.

Abstract

Studies of exhaustive exercise on marksmanship accuracy have been inconclusive and to date have not measured trigger pull latencies ((TPL), the time from target presentation to trigger pull) or considered the impact of added torso loads. PURPOSE: To examine the impact of exhaustive whole body exercise and torso loading on number of targets hit and TPL during a marksmanship task. METHODS: 12 males (mean±SD: height 1.77±0.06 m, body mass 77.0±9.4 kg) lifted a 20.5 kg box on to a 1.55 m high shelf until they could not maintain the pace of 12 lifts/ min. Within 30 s of ending this lifting task subjects started an 8 shot/min, 10 min long rifle marksmanship test using an EST 2000 electronic marksmanship range. During lifting and shooting subjects wore 3 different loads. CONTROL (CTL) = boots, uniform and helmet (5.9kg), LOAD1 (L1) =CTL plus a torso-borne load (24.3kg). LOAD2 (L2) =CTL and a heavier torso-borne load (29.9kg). Data were analyzed using Repeated Measures ANOVA with Tukey's HSD post hoc test. RESULTS: There were no differences in accuracy for the different load groups. All groups were ∼22% less accurate in the first 2 min sampling period than in the last 4 sampling periods (p<0.001). Overall TPL was faster (p<0.025) for CTL (2240 ms ±121) than L1 (2480ms±101) or L2 (2522ms±81). L2 engaged targets 14% slower in the first 4 min of the test than CTL (*, p<0.05, Table 1).TABLE 1: Trigger Pull Latency (ms)CONCLUSIONS: Exhaustive whole body exercise has a transient negative effect on accuracy regardless of load. With added torso loads, trigger pull latency is degraded immediately and sooner than in the unloaded condition. While this increased latency did not impact accuracy, increased time to engage the targets may have a negative impact on fighting effectiveness and survivability.