Efeitos do treinamento muscular inspiratório e da estimulação elétrica neuromuscular em pacientes com doença pulmonar obstrutiva crônica

Abstract

The primary pathophysiology of chronic obstructive pulmonary disease (COPD) is related to damage to the respiratory system. Nevertheless, given that it is a complex and heterogeneous disease, various extrapulmonary manifestations are evidenced in its progression, including peripheral and respiratory muscle dysfunction, reduced functional capacity, and health-related quality of life (HRQoL). Evidence has shown that patients with COPD also have significant deficits in postural balance and an increased risk of falls. However, the American Thoracic Society and European Respiratory Society’s statement on Pulmonary Rehabilitation (PR) briefly presents the expansion of the scope of outcome assessment to include balance, although it does not address interventions with the potential to improve it. Hence, it is highly relevant to investigate whether adjuvant modalities, such as inspiratory muscle training (IMT) and/or neuromuscular electrical stimulation (NMES), could potentiate the effects of PR and improve postural balance. Given the above, this study sought to analyze the effects of adding multimodal training (IMT and NMES) compared to adding individualized IMT or NMES to PR and compared to conventional PR in patients with COPD. This is a randomized clinical trial (identification no. NCT04387318) with four parallel groups that, in addition to the PR program, performed multimodal training (IMT + NMES), IMT, NMES, or exclusively conventional PR, for eight weeks, twice a week. The primary endpoint was static postural balance assessed by the force platform (COPap: amplitude of displacement of the center of pressure in the anteroposterior direction; COPml: amplitude of displacement of the COP in the medio-lateral direction; COPvel: COP displacement velocity and 95% ellipse area [EA]). Secondary endpoints comprised static and dynamic balance (Timed Up and Go test, Balance Evaluation Systems test, Berg Balance Scale, and Dynamic Foam-Laser Posturography), fear of falling (Falls Efficacy Scale-International-Brazil and Activities-specific Balance Confidence), peripheral muscle strength and endurance (dynamometry and 30-second sit to stand test), and respiratory (manovacuometry, incremental and constant tests), functional capacity (six-minute walk test), HRQoL (Saint George’s Hospital Questionnaire on Respiratory Disease [SGRQ]), peripheral and respiratory muscle architecture (ultrasonography), and laboratory biomarkers (inflammatory profile, endothelial function, oxidative stress, and muscle and DNA damage). The main findings showed that only in the multimodal training group was there a significant reduction in all postural sway variables (eyes open and closed: COPap: p=0.002, p<0.0001; COPml: p< 0.0001, p< 0.0001; COPvel: p=0.005, p=0.005, and EA: p=0.001, p=0.014), SGRQ total score (p=0.0001), echogenicity of the vastus intermedius (p=0.006) and significant increase in the antioxidant profile (Ferric Reducing Antioxidant Power: p=0.009; total antioxidant capacity: p=0.003). Nevertheless, there was no significant difference between the groups for any outcomes analyzed. Our results suggest that the addition of multimodal training of short duration and with reduced weekly frequency improved static postural balance, HRQoL, peripheral muscle architecture, and reduced oxidative stress in COPD patients enrolled in PR. However, this training could not potentiate the effects of PR on the outcomes considered. The potential implications of this study for clinical practice support the need to broaden the focus of PR by personalizing its components since combining different therapeutic strategies results in varying benefits.