Comparison of marker models for the analysis of the volume variation and thoracoabdominal motion pattern in untrained and trained participants

Respiratory assessment and the biomechanical analysis of chest and abdomen motion during

breathing can be carried out using motion capture systems. An advantage of this methodology is

that it allows analysis of compartmental breathing volumes, thoraco-abdominal patterns,

percentage contribution of each compartment and the coordination between compartments. In the

literature, mainly, two marker models are reported, a full marker model of 89 markers placed on

the trunk and a reduced marker model with 32 markers. However, in practice, positioning and

post-process a large number of markers on the trunk can be time-consuming. In this study, the

full marker model was compared against the one that uses a reduced number of markers, in order

to evaluate i) their capability to obtain respiratory parameters (breath-by-breath tidal volumes)

and thoracoabdominal motion pattern (compartmental percentage contributions, and coordination

between compartments) during quiet breathing, and ii) their response in different groups such as

trained and untrained, male and female. Although tests revealed strong correlations of the tidal volume values in all the groups (R2

>0.93), the reduced model underestimated the trunk volume compared with the 89 marker model. The

highest underestimation was found in trained males (bias of 0.43 L). The three-way ANOVA test

showed that the model did not influence the evaluation of compartmental contributions and the

32 marker model was adequate to distinguish thoracoabdominal breathing pattern in the studied

groups. Our findings showed that the reduced marker model could be used to analyse the

thoracoabdominal motion in both trained and untrained populations but performs poorly in

estimating tidal volume.