BackgroundOperation of infantry combat vehicle (ICV) influences the cardiorespiratory responses as well as the risk of vibration exposure on the crew members which adversely affect their performance and health.AimTo assess the effect of stress factors, that is, ICV’s compartmental temperature, relative humidity (RH) and vehicular vibration on the physiological parameters (heart rate (HR), respiratory frequency (RF), estimated core body temperature (ECT)) of the crew members during the ICV operation.MethodsA 1 hour run trial of the ICV operation was conducted with its crew members at their respective positions. Compartmental temperature and RH were monitored at an interval of every 15 min during the run trial. Physiological parameters were monitored continuously during the run trial. Whole body vibration (WBV) and hand-arm vibration (HAV) of the crew members were also measured during the run trial time.ResultsThe findings showed a strong positive correlation (p<0.05) between the increasing compartmental temperature and RH with its run trial time. Significant changes were observed in the physiological parameters (p<0.05) along with the increasing run trial time. Additionally, the physiological parameters showed a strong positive correlation with compartmental temperature and RH, respectively (p<0.05). Also, a significant increase (p<0.05) in the muscle strength was recorded after their exposure to ICV operation. The study also confirmed high level of WBV exposure of the crew members during the ICV operation.ConclusionIncrease in HR, RF and ECT along with increase in temperature and RH is a predictive indicator of physiological stress. Moreover, high levels of vibration exposure of various operations may bring deleterious effect on soldiers’ health as well as their performance. Proper ergonomic intervention can reduce exposure to vibration, physiological stress and increase comfort which may ultimately ensure an optimum performance of soldiers and successful completion of mission.

Multifaceted stress factors related to infantry combat vehicle (ICV) operation may be considered as major a source of cognitive workload, which may significantly impact the performance of infantry soldiers. The available literature on the effect of ICV’s operational environment on soldier’s cognitive workload is scanty or mostly unreported. The present study was designed to observe the effect of ICV operation on the i) cognitive workload ii) cognitive performance and iii) to study the association between cognitive workload and performance. Thirty soldiers [mean(SD)- age: 31.86(2.9) years, weight: 74.40(7.7) kg, and height: 171.33(3.42) cm] volunteered for this study. Their heart rate (HR), heart rate variability (HRV) and respiratory frequency (RF) were recorded at three time points 00th-05th, 25th-30th and 55th-60th minute during the ICV operation. ‘A’ letter cancellation task (ALCT) was conducted to assess cognitive performance, before and after ICV operation. The internal temperature and relative humidity (RH) of ICV were assessed at same three time-points. Repeated measure ANOVA and Wilcoxon signed ranks test were conducted to observe significant changes in HR, HRV, RF, and cognitive performance. Association between HRV and ALCT was assessed using Pearson’s bivariate correlation. Changes were considered significant when p-value was ≤ 0.05. Significant increase in the HR and RF were observed along with significant decrease in both time and frequency domain of HRV after ICV operation. Similarly, ALCT showed a significant increase in the total and net score, and an increased error score in post-ICV operation. A strong positive correlation was observed between the ICV operation run-trial time and the increasing compartmental temperature (r=0.99) and RH (r=0.89). HRV components showed a negative correlation with ALCT measures. One hour of ICV operation resulted in increased cognitive workload and a significant decrease in the cognitive task performance. Internal temperature and RH of ICV are potential physical stress factors affecting the soldier’s workload and performance.

BACKGROUND: Military training activities are typically challenging and push the soldiers toward their maximum limits of capabilities to improve proficiency in real time situations. In terms of injury prevention, unit performance, and overall morale, the individual's physical capabilities must be in concert to the job demands. Hormones play an important role in regulating various physiological processes including fuel utilization by exercising muscles. AIMS AND OBJECTIVES: This study was undertaken to quantify the hormonal demand of an intense military training event. MATERIALS AND METHODS: The study was conducted at a military training center on 25 male healthy soldiers who had completed 11 week training. Venous blood samples were drawn before and immediately after the event. RESULTS: In hormonal responses, the levels of epinephrine (P < 0.001), norepinephrine (P < 0.01), cortisol (P < 0.001), serotonin (P < 0.01), and aldosterone (P < 0.001) were significantly increased while testosterone (P < 0.001) was found significantly decreased after event. The present study demonstrated that the physical proficiency training activity was highly energy demanding due to significantly increased sympathoadrenergic responses and induced a high level of acute stress due to significant reduction of testosterone. In addition to this, the significantly increased serotonergic responses indicated that the level of fatigue was high during activity. CONCLUSION: The findings of the present study may be helpful in screening of individuals before inducting into such intense military training activity to minimize the risk of injuries.