Effects of Breathing Training and Nitrate on Exercise at Simulated Altitude

Participants perform supervised respiratory muscle training (RMT) using a handheld resistive breathing device designed to strengthen the inspiratory and expiratory muscles. Training sessions are conducted 5 days per week for approximately 4-6 weeks. Each session includes a series of resisted breathing maneuvers with progressively increased load as tolerated. The device is calibrated to maintain a constant pressure threshold to ensure consistent training intensity.

Participants use an identical handheld breathing device with minimal resistance, providing no meaningful training stimulus. The training schedule and session duration match those of the active RMT group to maintain participant blinding.

Participants consume a standardized dose of concentrated beetroot juice daily for the duration of the training period (approximately 4-6 weeks). The supplement provides a fixed quantity of dietary nitrate known to enhance nitric oxide availability and support vascular and metabolic function during exercise.

Participants consume a placebo beverage identical in color, taste, and appearance to the nitrate supplement but containing no active nitrate. The beverage is consumed daily following the same schedule as the active supplement.