Maximal Respiratory Pressure Reference Equations in Healthy Adults and Cut-off Points for Defining Respiratory Muscle Weakness

Introduction: Maximal inspiratory and expiratory pressures (PImax/PEmax) reference equations obtained in healthy people are needed to correctly interpret respiratory muscle strength. Currently, no clear cut-off points defining respiratory muscle weakness are available. We aimed to establish sex-specific reference equations for PImax/PEmax in a large sample of healthy adults and to objectively determine cut-off points for respiratory muscle weakness. Methods: A multicentre cross-sectional study was conducted across 14 Spanish centres. Healthy non-smoking volunteers aged 18–80 years stratified by sex and age were recruited. PImax/PEmax were assessed using uniform methodology according to international standards. Multiple linear regressions were used to obtain reference equations. Cut-off points for respiratory muscle weakness were established by using T-scores. Results: The final sample consisted of 610 subjects (314 females; 48 [standard deviation, SD: 17] years). Reference equations for PImax/PEmax included body mass index and a squared term of the age as independent variables for both sexes (p<0.01). Cut-off points for respiratory muscle weakness based on T-scores ≥2.5 SD below the peak mean value achieved at a young age were: 62 and 83cmH2O for PImax and 81 and 109cmH2O for PEmax in females and males, respectively. Conclusion: These reference values, based on the largest dataset collected in a European population to date using uniform methodology, help identify cut-off points for respiratory muscle weakness in females and males. These data will help to better identify the presence of respiratory muscle weakness and to determine indications for interventions to improve respiratory muscle function. (AU)

Maximal Respiratory Pressure Reference Equations in Healthy Adults and Cut-off Points for Defining Respiratory Muscle Weakness.

INTRODUCTION: Maximal inspiratory and expiratory pressures (PImax/PEmax) reference equations obtained in healthy people are needed to correctly interpret respiratory muscle strength. Currently, no clear cut-off points defining respiratory muscle weakness are available. We aimed to establish sex-specific reference equations for PImax/PEmax in a large sample of healthy adults and to objectively determine cut-off points for respiratory muscle weakness. METHODS: A multicentre cross-sectional study was conducted across 14 Spanish centres. Healthy non-smoking volunteers aged 18-80 years stratified by sex and age were recruited. PImax/PEmax were assessed using uniform methodology according to international standards. Multiple linear regressions were used to obtain reference equations. Cut-off points for respiratory muscle weakness were established by using T-scores. RESULTS: The final sample consisted of 610 subjects (314 females; 48 [standard deviation, SD: 17] years). Reference equations for PImax/PEmax included body mass index and a squared term of the age as independent variables for both sexes (p<0.01). Cut-off points for respiratory muscle weakness based on T-scores ≥2.5 SD below the peak mean value achieved at a young age were: 62 and 83cmH2O for PImax and 81 and 109cmH2O for PEmax in females and males, respectively. CONCLUSION: These reference values, based on the largest dataset collected in a European population to date using uniform methodology, help identify cut-off points for respiratory muscle weakness in females and males. These data will help to better identify the presence of respiratory muscle weakness and to determine indications for interventions to improve respiratory muscle function.

Effectiveness of nordic walking in patients with asthma: A study protocol of a randomized controlled trial.

BACKGROUND: Patients with asthma often consider their symptomatology a barrier to exercise, leading to a reduced physical activity level. This study aims to determine whether the effect of a Nordic walking (NW) training program plus education and usual care is superior to educational and usual care only, in terms of exercise tolerance and other health-related outcomes in patients with asthma. The second aim is to explore the patients' experience with the NW program. METHODS: A randomized controlled trial will be conducted with 114 adults with asthma recruited in sanitary area of A Coruña, Spain. Participants will be randomized to NW or control groups in blocks of six and in the same proportion in each group. Participants in the NW group will enrol in supervised sessions during eight weeks, three times/week. All participants will receive three educational sessions on asthma self-management plus usual care (S1 Appendix). Outcomes such as exercise tolerance (primary outcome), physical activity level, asthma-related symptoms and asthma control, dyspnea, lung function, handgrip strength, health related quality of life, quality of sleep, treatment adherence and healthcare resources use will be measured pre and postintervention, and at three and six months of follow-up. Participants in the NW group will additionally participate in focus groups. DISCUSSION: This is the first study analysing the effect of NW in patients with asthma. NW combined with education and usual care is expected to improve exercise tolerance, but also asthma-related outcomes. If this hypothesis is confirmed, a new community-based therapeutic approach will be available for patients with asthma. TRIAL REGISTRATION: Study registered in ClinicalTrials.gov with number of register NCT05482620.