Characterizing the respiratory muscle strength of male British Army infantry recruits

This study aimed to quantify respiratory muscle strength in infantry recruits during the Phase 1 Combat Infantry Course (CIC) to identify if respiratory muscle weakness was present. Seventy-six British Army infantry recruits volunteered to participate in the study with 36 participants completing the full data collection period. The strength of participants' inspiratory and expiratory muscles was assessed at weeks 1, 6, and 12 of the course. Mean inspiratory and expiratory muscle strength increased during the 12-week course by 13.8% and 11.5%, respectively. However, of the recruits remaining in the course at week 12, ~20% produced inspiratory and expiratory values below their age predicted value. The exact cause of the increase in respiratory muscle strength is unknown. Likely contributory factors include an increase in volume and/or intensity of physical exercise and a training adaptation resulting from progressive load carriage training. It was concluded that there are individuals with respiratory muscle strength below age predicted values at the end of the 12-week CIC; the impact of this finding on military task performance should be explored.