Evaluation Of Physiological, Endocrinal And Cognitive Responses After 5 Days Of Field Survival Conditions: 1700

Survival conditions can occur during military operations. These emergencies situations often need intensive physical performances performed with limited feeding and associated with high psychological stress. Little is known about the physiological, endocrinal and cognitive responses to survival, as well as alteration of physical and mental performances. PURPOSE: To determine consequences of field survival conditions on physical and cognitive performances and examine metabolic and endocrinal responses in well trained soldiers. METHODS: 8 French commando soldiers (age 28.4 ± 0.8, height 178 ± 1, body weight (BW) 74.3 ± 2.9) were monitored before and after the last 5 days of their field survival instruction. Anthropometric parameters (BW, fat mass), blood samples for metabolic (glycerol (GL), glucose (G) and free fatty acid (FFA) levels) and endocrinal responses (growth hormone (GH), insulin growth factor 1 (IGF-1), IGF-Binding Protein 3 (IGF-BP3)), and muscle strength characteristics were collected in resting conditions and after a 5-days field survival period. Both knee extensor and forearm muscles strength during isometric maximal voluntary contraction (MVC) and endurance time at 20% of MVC (ET20) were measured. Cognitive evaluation was done with a questionnaire. Two reconnaissance missions per day at moderate exercise intensity were performed, while subjects had to find their own food during the survival period. RESULTS: As expected, BW and fat mass were decreased (-5.4%, -13.5% p<0.05, respectively). Concerning blood parameters, both GL and G concentrations were unchanged while plasma FFA level increased (+147%, p<0.01). Plasma GH concentration increased (+200% p<0.05), associated with a surprisingly decrease of both IGF-1 and IGF-BP3 levels (-43%, -17%, p<0.05, respectively). Neither MVC of both knee extensor and forearm nor ET20 were altered after 5 days of caloric restriction. Cognitive function also remained unaffected by survival conditions. CONCLUSIONS: A short field survival period leads to lypolysis and adaptive response of the GH axis, without detectable alteration of both physical performance and cognitive status. These surprising findings could be explained by the high level of physical training and mental resilience of our subjects.