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Associations between diaphragm contractility and unilateral drop landing kinetics in individuals with bilateral
Shunya Nonoyama1, Tadashi Suga2, Tadao Isaka2
1Faculty of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan.
Introduction:
Recurrent lateral ankle sprains (LAS) are linked to neuromuscular and respiratory impairments, including reduced diaphragm contractility and altered landing mechanics. These deficits related to recurrent LAS may contribute to compromised ankle joint stability and increased risk of recurrent injury. However, no studies have explored the associations between diaphragm function and landing kinetics. This study aimed to examine the associations between diaphragm contractility, peak ground reaction force (GRF), and loading rate during a unilateral drop-landing task in individuals with bilateral recurrent LAS.
Methods:
Eighteen participants with bilateral recurrent LAS performed six trials of unilateral drop landing tasks on each leg on a force platform. The following kinetic measures were quantified: peak vertical, posterior, medial, and lateral GRF, as well as loading rates. An ultrasonographic assessment was performed to quantify right and left hemidiaphragm contractility.
Results:
The greater degree of right hemidiaphragm contractility was significantly correlated with greater loading rates and peak vertical GRF of the ipsilateral (right) and contralateral (left) legs (ρ = 0.53-0.70, P < 0.05). Less left hemidiaphragm contractility was significantly correlated with lower peak medial (ρ = -0.51, P = 0.033) and lateral GRF of the contralateral (right) leg (ρ = -0.50, P = 0.035).
Conclusion:
The observed associations of right hemidiaphragm contractility with vertical GRF and loading rates suggest that increased right diaphragm activity may serve as a compensatory strategy to enhance trunk stability in response to higher landing forces. Conversely, the negative correlations between left hemidiaphragm contractility and peak mediolateral GRF indicate that improved left diaphragm function may contribute to better force attenuation in the frontal plane. The observed correlations between the hemidiaphragms and GRF measures may suggest an asymmetrical neuromuscular maladaptations to recurrent LAS. These findings highlight the potential role of diaphragmatic exercises in rehabilitation programs for individuals with recurrent LAS, aiming to balance the functional demands on the right hemidiaphragm, optimize landing mechanics, and reduce risk of re-injury.
