Predicted exercise response to lung damage patterns. Theoretical human response to step-increase in workload (360 Watts at time = 0) with uniform or regional lung damage. Simulations were run for 3 conditions: healthy, uniform damage, and regional damage. Uniform damage was simulated as 20% lung weight gain across all segments. Regional damage represents the same total lung weight gain as uniform damage, confined to the right lung segments only (38.1% weight gain in right lung, calculated using volume fraction of right lung to total lung volume). (a) Workload output under each condition; deviation from the desired workload (360 watts) represents fatigue time. (b) Arterial O2 saturation profile for each condition.