Normal range of values for contractility and relaxation parameters of inspiratory muscles in healthy children: An exploratory study

Objectives To estimate normal range of values for the contractility and relaxation parameters of inspiratory muscles and compare them by sex, age, nutritional status and level of physical activity in healthy children. Working Hypothesis We hypothesized that healthy children present similar range of values for the contractility and relaxation parameters of inspiratory muscles. Study Design Exploratory study conducted between 2017 and 2018. Patient‐Subject Selection Healthy children aged 6 to 11 years without history of respiratory, cardiac, cerebrovascular or neuromuscular disease as well as no nasal congestion, influenza or known septum deviation were included. Methodology Anthropometric, spirometry and respiratory muscle strength data were assessed. Maximum rate of pressure development (MRPD), maximum relaxation rate (MRR), time constant of decay curve (τ), contraction time (CT) and half‐relaxation time (½ RT) were calculated from the nasal inspiratory pressure curve. Results The sample was composed of 110 children (55 boys) with 1.045 as mean z‐BMI‐score. MRPD range of values was 8.09% to 10.86% rise/10 ms, MRR range of values was 8.09% to 10.86% fall/10 ms, τ range of values was 36.41 to 49.88 ms, CT range of values was 200 to 276 ms, ½ RT range of values was 117.5 to 148 ms and MRPD/MRR range of values was 0.71 to 1.04. The contractility and relaxation parameters did not present significant differences among children when compared by sex, age, nutritional status, or level of physical activity groups (P > .05). Conclusions The contractility and relaxation parameters present similar values among children and they are not influenced by age, sex, nutritional status or physical activity level.