Concurrent Validity of the Static and Dynamic Measures of Inspiratory Muscle Strength: Comparison between Maximal Inspiratory Pressure and S-Index

Abstract

Objective: To verify the concurrent validity between the inspiratory muscle strength (IMS) values obtained in static (maximal inspiratory pressure [MIP]) and dynamic (S-Index) assessments.Methods: Healthy individuals were submitted to two periods of evaluation: i) MIP, static maneuver to obtain IMS, determined by the Mueller's maneuver from residual volume (RV) until total lung capacity (TLC); ii) and S-Index, inspiration against open airway starting from RV until TLC. Both measures were performed by the same evaluator and the subjects received the same instructions. Isolated maneuvers with differences < 10% were considered as reproducible measures.Results: Data from 45 subjects (21 males) were analyzed and that showed statistical difference between MIP and S-Index values (133.5 ± 33.3 and 125.6 ± 32.2 in cmH2O, respectively), with P=0.014. Linear regression showed r 2 =0.54 and S-Index prediction formula = 39.8+(0.75×MIP). Pearson's correlation demonstrated a strong and significant association between the measures with r=0.74. The measurements showed good concordance evidenced by the Bland-Altman test.Conclusion: S-Index and MIP do not present similar values since they are evaluations of different events of the muscular contraction. However, they have a strong correlation and good agreement, which indicate that both are able to evaluate the IMS of healthy individuals.

Incremental Ramp Load Protocol to Assess Inspiratory Muscle Endurance in Healthy Individuals: Comparison with Incremental Step Loading Protocol

“…In a previous study, we found that the values of S-Index are not the same as those of MIP. However, the two methods of IMS assessment had a strong and significant correlation ( r = 0.74 and P< 0.0001), as well as good concordance evidenced by the Bland-Altman analysis [ 16 ] . The rational application of S-Index, for IMS dynamic evaluation, refers to standardization of muscle contraction pattern adequate to support the dynamic endurance protocols, in contrast to protocols used in previous studies that based the resistance evaluation in a static force measurement (MIP) to support the ISLP [ 6 , 10 , 12 ] .…”

“…The S-Index values were those observed at the peak pressure generated by the pressure × time plot observed through BreatheLink Software 1.1. The S-Index was measured with a 30-second interval between maneuvers, being considered the highest value found in three reproducible maneuvers (difference < 10%) [ 16 ] . A short period of training was performed until the individual was familiar with the functioning of the device [ 17 , 18 ] .…”

“…Individuals were instructed to use a nasal clip and to not perform compensatory head and trunk movements during the maneuver. We also performed a previous correlation and concordance analyze between serial S-Index and MIP measurements with a sample of 45 individuals with a strong and significant correlation ( r = 0.74 and P< 0.0001) and good agreement [ 16 ] .…”

Exploring Indicators for Training Load Control in Young Swimmers: The Role of Inspiratory Spirometry Outcomes

“…The strength index calculation is based on the standard inspiratory muscle force–velocity relationship and its result is rated from poor to excellent [ 21 ]. S-INDEX and MIP have a strong correlation and good concordance, indicating that both are capable of evaluating the inspiratory muscle strength of healthy individuals [ 22 ]. The PIF consequently evaluates the ability of the inspiratory muscles to contract rapidly and overcome the resistance and elasticity inherent in the respiratory system.…”

Análise da satisfação de pacientes Pós-COVID-19 com telemonitoramento para o treinamento da musculatura inspiratória

“…Foram realizadas 10 inspirações com intervalo de 30 segundos cada, sendo necessárias de 8 a 10 inspirações para que alcance o melhor desempenho muscular inspiratório e evite a fadiga da musculatura envolvida. A avaliação S-Index visa analisar dinamicamente a pressão inspiratória máxima, a qual é obtida na contração rápida e vigorosa do diafragma associada ao uso dos músculos acessórios (Areias, et al, & Reis, 2020;Silva et al, 2018).…”