Previous studies have proposed only one prediction equation for respiratory muscle strength without taking into consideration differences between ages in pediatric population. In addition, those researches were single-center studies. The objective of this study was to establish reference equations for maximal inspiratory pressure (PImax) and maximal expiratory pressure (PEmax) in children and teenagers. In a multicenter study, 450 healthy volunteers were evaluated (aged 6–18yrs). There were included volunteers with normal lung function. We excluded volunteers who could not perform the tests; participated in physical activity more than twice a week; were born prematurely; smokers; chronic respiratory, cardiologic, and/or neurologic diseases; had acute respiratory disease during the prior three weeks. The volunteers were divided into two groups: Group 6–11 (6–11yrs) and Group 12–18 (12–18yrs). PImax and PEmax were measured according to statement. The mean PImax value was 85.6 (95%IC 83.6–87.6 cmH2O), and PEmax 84.6 (95%IC 85.5–86.2 cmH2O). The prediction equations for PImax and PEmax for Group 6–11 were 37.458–0.559 + (age * 3.253) + (BMI * 0.843) + (age * gender * 0.985); and 38.556 + 15.892 + (age * 3.023) + (BMI * 0.579) + (age * gender * 0.881), respectively (R2 = 0.34 and 0.31, P<0.001). The equations for Group 12–18 were 92.472 + (gender * 9.894) + 7.103, (R2 = 0.27, P = 0.006) for PImax; and 68.113 + (gender * 17.022) + 6.46 + (BMI * 0.927), (R2 = 0.34, P<0.0001) for PEmax. This multicenter study determined the respiratory muscle strength prediction equations for children and teenagers.

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Background: Patients with severe asthma need to be studied separately due to differences from less severe asthma. This is the first study to carry out a wide physical evaluation of children and adolescents with severe asthma. The objective was to evaluate maximal and submaximal exercise capacity, respiratory and peripheral muscle strength in children and adolescents with severe asthma. Methods:The study included children and adolescents (6 to 18 years) diagnosed with severe asthma, controlled in the last 4 weeks. The maximal exercise capacity was measured by the modified shuttle test (MST) and submaximal by the 6-min walk test. Respiratory muscle strength was evaluated by measuring maximal respiratory pressures and the peripheral strength through a handgrip.Results: Thirty patients were included, with mean age of 10.3 years, 63% female and 46.7% overweight or obese. Patients underperformed but reached more than 80% of expected in all evaluations. There was a moderate correlation between age and body mass index (BMI) with MST, maximal expiratory pressure and peripheral muscle strength. The correlation between MST and BMI was negative. There was a strong correlation between peripheral muscle strength and age. Peripheral muscle strength also correlated moderately with respiratory muscle strength and lung function. Conclusion:Children and adolescents with severe asthma had lower maximal and submaximal exercise capacity and reduced peripheral and respiratory muscle strength. These results are slightly below normal and very similar to patients with less severe asthma, allowing us to infer that patients with severe asthma have a good functional condition when the disease is controlled.

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