Variability of diaphragm structure among healthy individuals

Area of Science:

• Respiratory Physiology
• Biomechanics
• Human Anatomy

Background:

• The diaphragm's cross-sectional area (CSA(di)) relative to thoracic area (A(thor)) theoretically dictates inspiratory pump strength.
• Understanding these dimensions is crucial for assessing respiratory muscle function.

Purpose of the Study:

• To investigate the relationship between diaphragm and thoracic dimensions and body size in healthy adults.
• To determine the impact of weight-lifting training on these structural parameters.

Main Methods:

• Utilized ultrasonography and anthropometry to measure diaphragm thickness (t(di)), rib cage circumference (c(di)), CSA(di), and A(thor) in 37 healthy subjects.
• Compared measurements between subjects who did and did not engage in weight-lifting.

Main Results:

• Diaphragm and thoracic dimensions increased with height and body weight in untrained individuals, consistent with elastic similarity scaling.
• CSA(di)/A(thor) ratio showed significant variability and was not directly correlated with height or weight.
• Weight-trained adults exhibited thicker diaphragms and a greater CSA(di)/A(thor) ratio compared to untrained individuals.

Conclusions:

• Structural dimensions of the diaphragm and thorax display considerable, partly stature-dependent variability.
• These structural variations predict significant, non-stature-dependent variations in inspiratory strength.
• Weight training demonstrably increases the diaphragm's muscular cross-section.