Endurance exercise elicits skeletal muscle and systemic inflammation. Inflammation in response to endurance exercise is normally attenuated with adequate rest and recovery as skeletal muscle adapts with training. However, performing repeated bouts of prolonged and unaccustomed, muscle damaging (i.e., eccentric loading) endurance exercise may be detrimental to performance and limit the adaptive responses to exercise by diminishing the absorption of key nutrients. Warfighters are commonly exposed to such exercise bouts during sustained training and combat operations, the effects of which may be exacerbated by negative energy balance. Therefore, to define the putative role of energy balance on systemic inflammation, we will conduct a controlled laboratory study that simulates the physiological stressors imposed during sustained military training and combat operations to determine if systemic inflammation is exacerbated by underfeeding.~Twenty-six male, non-obese (body mass index 19.9-29.9 kg/m2), physically active adults will be recruited to participate in a 32 d, longitudinal study. The study is comprised of four sequential phases: 1) a 96 h testing period, 2) a 7 day recovery period (Recovery 1), 3) a second, 96 h testing period, and 4) a 14 d recovery period (Recovery 2). During testing, subjects will be randomized to consume either sufficient food (combat rations) to maintain energy balance or will be provided a restricted amount of food to elicit severe negative energy balance. Mineral absorption studies and will be conducted during each testing condition, energy balance and energy negative balance. This design will test the hypothesis that maintaining energy balance will attenuate systemic inflammation and its potential negative effects on whole-body metabolic homeostasis in response to physiological stressors.
The effects of prolonged negative energy balance, commonly observed in sustained military training and combat operations, on systemic inflammatory responses has not been determined. To define the putative role of energy balance on inflammation and its downstream effects, we will conduct a controlled laboratory study that simulates extensive physiological stressors to determine if inflammation is exacerbated by underfeeding. This design will test the hypothesis that maintaining energy balance will attenuate systemic inflammation and its potential negative effects on whole-body metabolic homeostasis in response to physiological stressors.