Changes in co-contraction magnitude during functional tasks following anterior cruciate ligament reconstruction: A systematic review.

BACKGROUND: Anterior cruciate ligament reconstruction (ACLR) is a common orthopedic surgery procedure whose incidence has increased over the past few decades. Nevertheless, it is believed that neuromuscular control remains altered from the early stages after ACLR to later years. Therefore, the aim of this study was to systematically evaluate the magnitude of co-contraction during functional tasks in subjects with unilateral ACLR. METHODS: A systematic review design was followed. The search strategy was conducted in PubMed, Scopus, EBSCO, PEDro, Cochrane Library, and Web of Science databases from inception to March 2024. The inclusion criteria involved studies using electromyography (EMG) data to calculate muscle pair activation via the co-contraction index (CCI) in ACLR individuals during functional tasks. The Preferred Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed, and study quality was evaluated using National Institutes of Health (NIH) Study Quality Assessment Tools. RESULTS: The search strategy found a total of 792 studies, of which 15 were included in this systematic review after reviewing the eligibility criteria. The magnitude of co-contraction was assessed in a total of 433 ACLR individuals and 206 controls during functional tasks such as hop, drop-land, step-up/step-down, and gait. Overall, approximately 79.6% of individuals who had undergone ACLR exhibited increased levels of co-contraction magnitude in the ACLR limb, while 8.5% showed low co-contraction levels. CONCLUSIONS: The findings of the review suggest that, during functional tasks, most individuals who have undergone ACLR exhibit changes of co-contraction magnitude in the involved limb.

Interlimb Coordination during Double Support Phase of Gait in People with and without Stroke.

This study aims to identify differences between participants with and without stroke regarding the ipsilesional and contralesional lower limbs kinematics, kinetics, muscle activity and their variability during double support phase of gait. Eleven post-stroke and thirteen healthy participants performed 10 gait trials at a self-selected speed while being monitored by an optoelectronic motion capture system, two force plates and an electromyographic system. The following outcomes were evaluated during the double support: the time and the joint position; the external mechanical work on the centre of mass; and the relative electromyographic activity. Both, contralesional/ipsilesional and dominant/non-dominant of participants with and without stroke, respectively, were evaluated during double support phase of gait in trailing or leading positions. The average value of each parameter and the coefficient of variation of the 10 trials were analysed. Post-stroke participants present bilateral decreased mechanical work on the centre of mass and increased variability, decreased contralesional knee and ankle flexion in trailing position, increased ipsilesional knee flexion in leading position and increased variability. Increased relative muscle activity was observed in post-stroke participants with decreased variability. Mechanical work on the centre of mass seems to be the most relevant parameter to identify interlimb coordination impairments in post-stroke subjects.

Forward trunk lean with arm support affects the activity of accessory respiratory muscles and thoracoabdominal movement in healthy individuals.

Despite the reported benefits of postures involving leaning the trunk forward with arm support for relieving dyspnea, how those postures influence the mechanics of breathing remains unclear. In response, the aim of the study reported here was to evaluate how posture (i.e., standing and sitting) and leaning the trunk forward with arm support affect the activity of accessory respiratory muscles and thoracoabdominal movement in healthy individuals. Thirty-five volunteers (15 males and 20 females) aged 18-29 years breathed with the same rhythm in standing and sitting positions while upright and while leaning the trunk forward with arm support. Surface electromyography was performed to assess the activity of accessory inspiratory (i.e., during inspiration) and abdominal (i.e., during inspiration and expiration) muscles, and a motion capture system was used to assess thoracoabdominal movement. Results revealed that upper trapezius activity was significantly lower in forward-leaning postures than in upright ones (P = 005; ηp2 = 0.311), although the activity of the sternocleidomastoideus and scalenus (P < 0.001; ηp2 = 0.427-0.529), along with the anterior-to-posterior movement of the upper ribcage (P < 0.001; ηp2 = 0.546), were significantly greater in forward-leaning postures than in upright ones. The activity of the external oblique and transversus abdominis/internal oblique was significantly lower in sitting than in standing postures (P < 0.050; ηp2 = 0.206-0.641), and though the activity of the transversus abdominis/internal oblique was significantly lower in forward-leaning than in upright postures (P ≤ 0.001; ηp2 = 0.330-0.541), a significantly greater anterior-to-posterior movement of the abdomen was observed (P < 0.001; ηp2 = 0.662). However, the magnitude of the lower ribcage's medial-to-lateral movement was significantly lower in forward-leaning than in upright postures (P = 0.039; ηp2 = 0.149). Leaning the trunk forward with arm support not only increased the use of accessory inspiratory muscles but also decreased the use of the transversus abdominis/internal oblique, which improved thoracoabdominal movement.

Inter- and intra-rater reliability of nasal auscultation in daycare children.

BACKGROUND: The aim of this study was to assess nasal auscultation's intra- and inter-rater reliability and to analyze ear and respiratory clinical condition according to nasal auscultation. METHODS: Cross-sectional study performed in 125 children aged up to 3 years old attending daycare centers. Nasal auscultation, tympanometry and Paediatric Respiratory Severity Score (PRSS) were applied to all children. Nasal sounds were classified by an expert panel in order to determine nasal auscultation's intra and inter- rater reliability. The classification of nasal sounds was assessed against tympanometric and PRSS values. RESULTS: Nasal auscultation revealed substantial inter-rater (K=0.75) and intra-rater (K=0.69; K=0.61 and K=0.72) reliability. Children with a "non-obstructed" classification revealed a lower peak pressure (t=-3.599, P<0.001 in left ear; t=-2.258, P=0.026 in right ear) and a higher compliance (t=-2,728, P=0.007 in left ear; t=-3.830. P<0.001 in right ear) in both ears. There was an association between the classification of sounds and tympanogram types in both ears (X=11.437, P=0.003 in left ear; X=13.535, P=0.001 in right ear). Children with a "non-obstructed" classification had a healthier respiratory condition. CONCLUSIONS: Nasal auscultation revealed substantial intra- and inter-rater reliability. Nasal auscultation exhibited important differences according to ear and respiratory clinical conditions. Nasal auscultation in pediatrics seems to be an original topic as well as a simple method that can be used to identify early signs of nasopharyngeal obstruction.

Abdominal muscle activity during breathing in different postural sets in healthy subjects.

OBJECTIVE: This study aims to evaluate the effect of different postural sets on abdominal muscle activity during breathing in healthy subjects. METHODS: Twenty-nine higher education students (20.86 ± 1.48 years; 9 males) breathed at the same rhythm (inspiration: 2 s; expiration: 4 s) in supine, standing, tripod and 4-point-kneeling positions. Surface electromyography was performed to assess the activation intensity of rectus abdominis, external oblique and transversus abdominis/internal oblique muscles during inspiration and expiration. RESULTS: During both breathing phases, the activation intensity of external oblique and transversus abdominis/internal oblique was significantly higher in standing when compared to supine (p ≤ 0.001). No significant differences were found between tripod position and 4-point-kneeling positions. Transversus abdominis/internal oblique activation intensity in these positions was higher than in supine and lower than in standing. CONCLUSIONS: Postural load and gravitational stretch are factors that should be considered in relation to the specific recruitment of abdominal muscles for breathing mechanics.

The effect of inspiratory and expiratory loads on abdominal muscle activity during breathing in subjects "at risk" for the development of chronic obstructive pulmonary disease and healthy.

The abdominal muscle activity has been shown to be variable in subjects with chronic obstructive pulmonary disease (COPD) when respiratory demand increases and their recruitment pattern may change the mechanics, as well as the work and cost of breathing. The scientific evidence in subjects "at risk" for the development of COPD may be important to understand the natural history of this disease. This study aims to evaluate the effect of inspiratory and expiratory loads on the abdominal muscle activity during breathing in subjects "at risk" for the development of COPD and healthy. Thirty-one volunteers, divided in "At Risk" for COPD (n=17; 47.71±5.11years) and Healthy (n=14; 48.21±6.87years) groups, breathed at the same rhythm without load and with 10% of the maximal inspiratory or expiratory pressures, in standing. Surface electromyography was performed to assess the activation intensity of rectus abdominis (RA), external oblique and transversus abdominis/internal oblique (TrA/IO) muscles, during inspiration and expiration. During inspiration, in "At Risk" for COPD group, RA muscle activation was higher with loaded expiration (p=0.016); however, in Healthy group it was observed a higher activation of external oblique and TrA/IO muscles (p<0.050). During expiration, while in "At Risk" for COPD group, RA muscle activation was higher with loaded inspiration (p=0.009), in Healthy group TrA/IO muscle showed a higher activation (p=0.025). Subjects "at risk" for the development of COPD seemed to have a specific recruitment of the superficial layer of ventrolateral abdominal wall for the mechanics of breathing.

Abdominal muscle activity during breathing in different postures in COPD "Stage 0" and healthy subjects.

This study aims to evaluate the effect of different postures on the abdominal muscle activity during breathing in subjects "at risk" for the development of chronic obstructive pulmonary disease (COPD) and healthy. Twenty-nine volunteers, divided in "At Risk" for COPD (n=16; 47.38±5.08years) and Healthy (n=13; 47.54±6.65years) groups, breathed at the same rhythm in supine, standing, tripod and 4-point-kneeling positions. Surface electromyography was performed to assess the activation intensity of rectus abdominis, external oblique and transversus abdominis/internal oblique (TrA/IO) muscles, during inspiration and expiration. From supine to standing, an increased activation of all abdominal muscles was observed in "At Risk" for COPD group; however, in Healthy group, TrA/IO muscle showed an increased activation. In both groups, the TrA/IO muscle activation in tripod and 4-point kneeling positions was higher than in supine and lower than in standing. Subjects "at risk" for the development of COPD seemed to have a specific recruitment of the superficial layer of ventrolateral abdominal wall for the synchronization of postural function and mechanics of breathing.

Abdominal muscle activity during breathing with and without inspiratory and expiratory loads in healthy subjects.

Central Nervous System modulates the motor activities of all trunk muscles to concurrently regulate the intra-abdominal and intra-thoracic pressures. The study aims to evaluate the effect of inspiratory and expiratory loads on abdominal muscle activity during breathing in healthy subjects. Twenty-three higher education students (21.09±1.56years; 8males) breathed at a same rhythm (inspiration: two seconds; expiration: four seconds) without load and with 10% of the maximal inspiratory or expiratory pressures, in standing. Surface electromyography was performed to assess the activation intensity of rectus abdominis, external oblique and transversus abdominis/internal oblique muscles, during inspiration and expiration. During inspiration, transversus abdominis/internal oblique activation intensity was significantly lower with inspiratory load when compared to without load (p=0.009) and expiratory load (p=0.002). During expiration, the activation intensity of all abdominal muscles was significantly higher with expiratory load when compared to without load (p<0.05). The activation intensity of external oblique (p=0.036) and transversus abdominis/internal oblique (p=0.022) was significantly higher with inspiratory load when compared to without load. Transversus abdominis/internal oblique activation intensity was significantly higher with expiratory load when compared to inspiratory load (p<0.001). Transversus abdominis/internal oblique seems to be the most relevant muscle to modulate the intra-abdominal pressure for the breathing mechanics.