Nerea Molina-Hernández

Background: Hallux limitus (HL) is a restriction of first metatarsophalangeal joint dorsiflexion, commonly linked to foot biomechanics-related disorders or trauma, increasing sports injury risk. It involves plantar fascia tension, compensations, and tendon adaptations. Rehabilitative ultrasound imaging (RUSI) accurately assesses musculoskeletal changes, supporting physiotherapy evaluation and the study of HL-related structural adaptations. Objectives: Comparing the thickness and cross-sectional area (CSA) of flexor hallucis brevis (FHB), flexor digitorum brevis (FDB), abductor hallucis (AbH), and quadratus plantae (QP) muscles, as well as the thickness of the plantar fascia (PF), Achilles tendon (AT), and plantar calcaneal fat pad (CFP), between participants with and without HL. Methods: Case–control study included 80 basketball players recruited from semi-professional teams by consecutive non-probabilistic sampling. Participants were divided into two groups: an HL group (n = 40) and a healthy group (n = 40). Musculotendinous parameters were assessed using RUSI. Results: The FDB, FHB, AB, and QP showed significant reductions in thickness and CSA at rest and at contraction in the HL group. PF thickness increased in participants with HL, while CFP thickness decreased significantly. Significance was established at (p < 0.05). Conclusions: HL participants exhibited reduced muscle size and CSA, increased PF, and lower CFP thicknesses, indicating adaptive tissue alterations.

The aim of the present study was to determine the gender respiratory differences of bilateral diaphragm thickness, respiratory pressures, and pulmonary function in patients with low back pain (LBP). A sample of 90 participants with nonspecific LBP was recruited and matched paired by sex (45 women and 45 men). Respiratory outcomes included bilateral diaphragm thickness by ultrasonography, respiratory muscle strength by maximum inspiratory (MIP) and expiratory (MEP) pressures, and pulmonary function by forced expiratory volume during 1 s (FEV₁), forced vital capacity (FVC) and FEV₁/FVC spirometry parameters. The comparison of respiratory outcomes presented significant differences (p < 0.001), with a large effect size (d = 1.26–1.58) showing means differences (95% CI) for MIP of −32.26 (−42.99, −21.53) cm H₂O, MEP of −50.66 (−64.08, −37.25) cm H₂O, FEV₁ of −0.92 (−1.18, −0.65) L, and FVC of −1.00 (−1.32, −0.69) L, with lower values for females versus males. Gender-based respiratory differences were presented for maximum respiratory pressures and pulmonary function in patients with nonspecific LBP. Women presented greater inspiratory and expiratory muscle weakness as well as worse lung function, although these differences were not linked to diaphragm thickness during normal breathing.

Diaphragmatic weakness and thickness reduction have been detected in athletes with lumbopelvic pain (LPP). Strength training of inspiratory muscles may be necessary for athletes with LPP. Inspiratory muscle training (IMT) and visual biofeedback by rehabilitative ultrasound imaging (RUSI) have been proposed as possible interventions. Here, we determine the effectiveness of visual biofeedback by RUSI with a proposed novel thoracic orthotic device to facilitate diaphragmatic contraction in conjunction with high-intensity IMT in athletes with non-specific LPP. A single-blinded, parallel-group, randomized clinical trial was performed (NCT04097873). Of 86 participants assessed for eligibility, 64 athletes with non-specific LPP (39 males and 25 females; mean age, 33.15 ± 7.79 years) were recruited, randomized, analyzed and received diaphragm visual biofeedback by RUSI in conjunction with high-intensity IMT (RUSI+IMT; n = 32) or isolated high-intensity IMT (IMT; n = 32) interventions for 8 weeks. Diaphragmatic thickness during normal breathing, maximum respiratory pressures, pain intensity, pressure pain threshold on lumbar musculature, disability by the Roland–Morris questionnaire, quality of life by the SF-12 questionnaire and spirometry respiratory parameters were assessed at baseline and after the 8-week intervention. There were significant differences (p = 0.015), within a medium effect size (Cohen’s d = 0.62) for the forced expiratory volume in 1-s (FEV₁), which was increased in the RUSI+IMT intervention group relative to the IMT alone group. Adverse effects were not observed. The rest of the outcomes did not show significant differences (p > 0.05). Diaphragm visual biofeedback by RUSI with the proposed novel thoracic orthotic device in conjunction with high-intensity IMT improved lung function by increasing FEV₁ in athletes with non-specific LPP.