Respiratory Muscle Strength is an important tool to diagnose different disorders. Reference equations considered different populations and methodologies. However, there is no agreement on what is the ideal equation to use. The aim of this study was to compare and correlate the measured values of maximal respiratory pressures with those demonstrated by equations described in literature. The sample consisted of 90 healthy individuals aged from 6 to 12 years old. Anthropometric, spirometric and manometric measurements were performed. The comparison between measured and predicted values was significantly different, showing the mean male maximum inspiratory pressure (maxIP) (80.65±26.78) to be higher than that predicted by Wilson et al. (67.40±5.65, p<0.001) and Schmidt et al. (70.69±21.70, p<0.05). The mean male maximum expiratory pressure (maxEP) (84.35±23.16) was lower than the one predicted by Domènech-Clar et al. (92.25±16.90, p<0.01) and higher than the one predicted by Schmidt et al. (72.78±13.62 p<0.001). The mean of female individuals' maxIP (76.14±26.08) was higher than that predicted by Wilson et al. (57.96±6.04, p<0.001), Schmidt et al. (68.54±7.08, p<0.01), and Domènech-Clar et al. (67.61±11.17, p<0.01). The mean female maxEP (74.55±20.05) was higher than the ones predicted by Wilson et al. (66.65±9.55, p<0.001) and lower than the one predicted by Domènech-Clar et al. (81.16±14.37, p<0.01). The correlations between measured and predicted values were from low to medium magnitude (range r=0.1 to 0.5) being significant for males when maxIP was correlated with that predicted by Wilson et al. (p<0.01) and Domènech-Clar et al. (p<0.05). For females, both correlations were significant (maxIP p<0.01; maxEP p<0.05). It was concluded that the equations failed to predict the values of maximum respiratory pressures, reinforcing the need for new equations of respiratory muscle strength.
muscle strength; reference values; respiratory muscles
