Muscle oxygenation and gait parameters during exercise in adults with chronic lung diseases versus healthy controls

We aimed to compare muscle oxygenation during exercise and gait parameters between adults with CLD and their age and sex matched healthy controls.

The study included 36 adults with CLD (18F/18M, 34.94±14.01) and 18 controls (9F/9M, 34.78±11.02). Of the CLD group, 6 (16.67%) had chronic obstructive pulmonary disease, 5 (13.89%) had asthma, 15 (41.67%)  had bronchiectasis, 5 (13.89%) had cystic fibrosis and 5 (13.89%) had primary ciliary dyskinesia. The SmO₂ was measured using near-infrared spectroscopy on dominant vastus lateralis during 6-minute walk test (6MWT). Pre- and post-6MWT responses (Δ) of heart rate (HR), oxygen saturation (SpO₂), and dyspnea, leg and general fatigue perceptions were recorded. Gait parameters (step cycle, walking speed, steps per minute, and ambulation index) were assessed using the gait analysis device.

The 6MWT distances were similar between groups (533.46±89.98 m in the CLD group and 577.43±62.78 m in the control group (p=0.069). There were no differences in ΔHR, ΔSpO₂, Δgeneral and Δleg fatigue perceptions between groups (p=0.332, p=0.333, p=0.414, p=0.232, respectively), even though CLD group had a significantly higher Δdyspnea perception than that of controls (p=0.024). The post-6MWT SmO₂ was lower, while total hemoglobin was higher in the CLD group than those of controls (p=0.003, p=0.029, p=0.034, respectively). Gait analysis showed that higher average speed, distance, average walking speed, and average step cycle in the control group (p0.001, p=0.003, p0.001, p=0.005, respectively).

Adults with CLD have lower muscle oxygenation and higher hemoglobin levels during exercise, even when they have similar functional exercise capacity compared with their age and sex matched healthy controls. Low muscle oxygenation despite higher hemoglobin levels during exercise in CLD group compared to the controls may indicate inadequate oxygen transport to the muscles and reduced oxygen utilization efficiency in the CLD group. This may possibly contribute to impaired gait parameters in CLD group to reduce the energy expenditure during walking as a compensating mechanism. Further studies are needed to enhance our findings regarding SmO₂ and gait in adults with CLD.

Assessment and determination of SmO₂ and gait parameters during exercise in CLD enables insights into exercise responses of muscles and gait differences, allowing physiotherapists to customize personalized rehabilitation programs based on muscle performance and gait parameters.