The Effects of Cold Exposure, Hypoxia, and Fatigue on Pistol Marksmanship and Target Engagement Decision Making in Trained Marksmen.

ABSTRACT: Segovia, M, Salmon, OF, Ugale, C, and Smith, CM. The effects of cold exposure, hypoxia, and fatigue on pistol marksmanship and target engagement decision making in trained marksmen. J Strength Cond Res XX(X): 000-000, 2024-This study aimed to examine the effects of cold exposure, hypoxia, and fatigue on pistol marksmanship and target engagement in trained marksmen. Twelve healthy subjects (mean ± SD age: 28.8 ± 4.0 years) performed 3 testing visits under normal/normoxic [Norm21] (24° C; 21% FiO2), cold/normoxic [Cold21] (10° C; 21% FiO2), and cold/hypoxic [Cold14] (10° C; FiO2: 14.3) conditions. Pistol marksmanship and target engagement were assessed through draw time (DT) and shoot-no-shoot (SNS) courses of fire. The 2 protocols were performed before (TpreF) and immediately after (TpostF) a sandbag deadlift fatiguing protocol. Significance was set at p < 0.05. Significant condition × time interactions (p = 0.01-0.03) were found for accuracy SNS (SNSacc), misses SNS (SNSmiss), and total shots SNS (SNStot). Follow-up analyses indicated that SNSacc increased by 14.3% (p = 0.03), SNSmiss decreased by 34.7% (p = 0.02), and SNStot decreased by 10.6% (p = 0.04) from TpreF to TpostF during the Cold21 condition alone. No significance was found for these in the Norm21 (p = 0.08-0.22) or Cold14 (p = 0.18-0.47) conditions. Total time (SNST) to completion of the SNS (p = 0.09) and DT (p = 0.14) showed no significance across time or condition. Significant difference across time for Cold14 (p = 0.03-0.02) for reaction time was found. Exercise likely resulted in increased thermogenesis that improved tactically relevant motor skills including SNSacc, decreased SNSmiss, and SNStot in Cold21, but not Cold14. The additive effect of hypoxia coupled with exercise in the Cold14 condition did not improve tactical performance, suggesting multi-stressor environments result in competing physiological responses. Tactical strength and conditioning specialists as well as operators should aim to improve thermoregulation during Cold21 conditions, with exercise as a possible intervention.

Impact of acute hypoxic exposure on neuromuscular and hemodynamic responses during step intensity dynamic constant external resistance leg extension exercise.

OBJECTIVES: This study examined the effects of acute normoxic and hypoxic exposure on neuromuscular and hemodynamic physiological responses performed during dynamic step muscle actions. METHODS: Thirteen recreationally active men (mean ± SD age: 21.2 ± 2.9 yrs) performed dynamic leg extensions unilaterally under Normoxic (FiO2 = 21 %) and Hypoxic (FiO2 = 13 %) conditions in a randomized order at 20 %, 40 %, 60 %, 80 %, and 100 % of their maximal strength. Electromyographic (EMG) amplitude, EMG frequency, (Oxygenated and Deoxygenated hemoglobin; OxyHb, DeoxyHb), Total hemoglobin (TotalHb), and skeletal muscle tissue oxygenation status (StO2) were measured from the vastus lateralis during all contractions. RESULTS: There were no detectable differences in the neuromuscular responses between normoxia and hypoxia for EMG amplitude (p = 0.37-0.74) and frequency (p = 0.17-0.83). For EMG amplitude there were general increases with intensity (p < 0.01-0.03). EMG frequency remained similar from 20% to 80% and then increased at 100 % effort (p = 0.02). There was no significant difference in patterns of responses for OxyHb (p = 0.870) and TotalHb (p = 0.200) between normoxia and hypoxia. StO2 (p = 0.028) decreased and DeoxyHb (p = 0.006) increased under hypoxia compared to normoxia during dynamic step muscle actions performed in a randomized order. CONCLUSION: Unlike fatigue, acute hypoxemia in an unfatigued state does not impact the localized neuromuscular responses, but minimally impacts the hemodynamic responses.

The impact of cold, hypoxia, and physical exertion on pistol accuracy and tactical performance.

The purpose of this study was to examine the impact of independent cold and combined cold and hypoxic exposures on operational-specific task performance including pistol marksmanship, pistol magazine reload ability, and subjective and objective thermal indices before and after a whole-body physical exertional task. Twelve participants were exposed to Thermoneutral Normoxic (24 °C; FiO2 21%), Cold Normoxic (10 °C; FiO2 21%), and Cold Hypoxic (10 °C; FiO2 14%) conditions for 30min before performing pistol marksmanship at distances of 6.40 and 13.72m and a pistol magazine reload task before and after 3 sets of sandbag deadlifts at 50% body mass. Thermal perception and hand temperatures were collected before and after the physical exertion task. There were no significant differences in Pistol Accuracy performance at distances of 6.40 and 13.72m due to physical exertion, cold, or hypoxia. Following physical exertion, Pistol Accuracy was similar between Thermoneutral and Cold Normoxic conditions but lead to 17% and a 10% reduction in performance during the Cold Hypoxic condition, compared to Thermoneutral and Cold Normoxic conditions. There was no change in Pistol Accuracy for the Thermoneutral Normoxic condition. The pistol magazine reload task was not impacted by physical exertion, but there was a reduction in performance in Cold Normoxic 21% (4.04s) and Cold Hypoxic 16% (3.08s) conditions. Physical exertion did not impact hand temperature but did increase thermal perception scores for all conditions. These findings indicate that cold exposure reduced both tactical dexterity and pistol marksmanship, however, physical exertion may offset these deficits via an increase in thermal perception. Additionally, hypoxemia was the primary mediator of marksmanship performance in cold hypoxic environments following an acute bout of physical exertion. Thus, in cold mountainous environments, marksmen should be aware of their elevation and utilize brief episodes of physical activity to enhance their thermal state when marksmanship is a priority for operational success.