What do you recommend as most objective and accurate test or measurement to assess RMW?

What do you recommend as most objective and accurate test or measurement to assess RMW?

The definition of RMW is that the respiratory muscle strength is reduced to equal or less to 70% of predicted value, assessed by maximum inspiratory or expiratory strength (MIP/MEP). Additional indicators for/manifestations of RMW include dyspnea, reduced exercise tolerance, dysphagia, dysphonia, etc.