Effects of global postural alignment on posture-stabilizing synergy and intermuscular coherence in bipedal standing.

Clinicians frequently assess and intervene on postural alignment; however, notions of what constitutes good postural alignment are variable. Furthermore, the majority of current evidence appeals either to population norms or defines good postural alignment as the negation of what has been observed to correlate with pathology. The purpose of this study was to identify affirmative indicators of good postural alignment in reference to motor control theory. Electromyography (anterior leg, posterior leg, and trunk muscles) and motion capture data were acquired from 13 participants during 4 min bipedal standing trials in 4 conditions: control, - 10%, + 30%, and + 60% of subject-specific anterior limits of stability. Synergistic kinematic coordination was quantified via the uncontrolled manifold framework, and correlated neural drive was quantified in posture-relevant muscle groups (anterior, posterior, and trunk) via intermuscular coherence. Multilevel models assessed the effects of sagittal plane alignment on both outcomes. We observed a within-subjects fixed effect in which kinematic synergistic coordination decreased as subjects became more misaligned. We also observed within-subjects fixed effects for middle- and high-frequency intermuscular coherence in the posterior group (increased coherence with increased misalignment) and for trunk intermuscular coherence across all frequency bands (decreased coherence with increased misalignment). Our findings indicate that it may be possible to describe healthy postural alignment in light of referent control theory. Greater misalignment with respect to vertical is associated with compromises in synergistic control of posture and increased corticospinal drive to specific muscle groups. These results suggest that postural alignment may not simply be an empirical phenomenon.

Utility of performance-based outcome measures (PBOMs) used in fall risk assessment tools for older adults.

This study investigated the diagnostic accuracy of different clusters of performance based outcome measures (PBOMs) recommended by two consensus-based guidelines: Stopping Elderly Accidents, Deaths, and Injuries (STEADI), and those recommended by a systematic review completed by the American Physical Therapy Association and Academy of Geriatric Physical Therapy (APTA-SR, APTA-SR3). 33 community-dwelling older adults (25 females, 8 males) aged mean 79.45 ±â€¯7.64 years participated in this study. Participants completed a fall history questionnaire and were evaluated via a battery of PBOMs for comparative analysis. The diagnostic accuracy of each PBOM cluster was analyzed retrospectively (previous 1 year fall history) and prospectively (6 month follow up). Retrospective analysis revealed the APTA-SR3 had the highest clinical utility and diagnostic accuracy: Sp 88.24% (63.56-98.54), Sn 62.5% (35.43-84.8), LR+ 2.35 (1.22-4.53), LR- 0.19 (0.05-0.73), accuracy 70.22% (51.83-84.81). Prospective analysis revealed the cluster of the APTA-SR and APTA-SR3 had identical diagnostic accuracy: Sn 100% (39.76-100), Sp 43.75% (19.75-70.12), LR+ 1.78 (1.15-2.74), LR- 0 (0), accuracy 60.62% (36.63-81.36). The APTA-SR 3 cluster demonstrated the highest diagnostic accuracy and in this study was the most effective and efficient group of PBOMs to identify fall risk in community dwelling older adults.