Trunk Stability in Dynamic Movement

Abstract

Spinal stability has been characterized in static but not in dynamic movements. The goal of this study was to determine whether movement pace and direction of dynamic trunk flexion influence the control of spinal stability. Twenty healthy subjects performed dynamic lifting movements at 20 and 40 cycles per minute. Lyapunov exponents were calculated from the measured trunk kinematics to estimate stability. Complexity of torso dynamics required at least five embedded dimensions thereby indicating that torso dynamics requires more than the 3-dimensions of movement for sufficient characterization. Dynamic stability is was greater in slow lifting movement than in fast movements. Asymmetric movements demonstrated greater multi-dimensional kinematic divergence than asymmetric movements. This indicates that the sagittal plane of movement may not be a principle dynamic axis of torso movement. Results provide biomechanical insight regarding the role of workplace design and risk of musculoskeletal instability in dynamic lifting tasks.

Muscle fatigue does not lead to increased instability of upper extremity repetitive movements

“…Slopes of mean log divergence curves were calculated over 0 to 1 cycles $\left({\lambda }_S^{\ast }\right)$ and over 4 to 10 cycles $\left({\lambda }_L^{\ast }\right)$ (Dingwell and Marin, 2006). These calculations are sensitive to sample size (Granata and England, 2006) and number of cycles (Bruijn et al, 2009). Each Pre/Post trial was re-sampled to 36,000 total data points, resulting in <1% change in the length of each time series.…”

Differentiating fall-prone and healthy adults using local dynamic stability

“…The local dynamic stability has also been successfully applied to examine the underlying dynamics of specific body segments, including the knee joint (Stergiou et al . 2004) and trunk segment (Granata and England 2006) and slow-time-scale physiological changes such as fatigue (Yoshino et al . 2004).…”

Gait dynamics, fractals and falls: Finding meaning in the stride-to-stride fluctuations of human walking

“…Before beginning, it is important to note that because of space constraints, this review considers only a subset of the reports on this topic. For complementary perspectives, the reader is referred to other pertinent reviews (Chau, 2001a(Chau, , 2001bChau, Young, & Redekop, 2005;Hausdorff, 2005) as well as parallel studies by others (Buzzi, Stergiou, Kurz, Hageman, & Heidel, 2003;Costa, Peng, Goldberger, & Hausdorff, 2003;Dingwell, Cusumano, Cavanagh, & Sternad, 2001;Dingwell, Gu Kang, & Marin, 2006;England & Granata, 2007;Georgoulis, Moraiti, Ristanis, & Stergiou, 2006;Granata & England, 2006;Kurz et al, 2003;Kurz & Stergiou, 2005;Stergiou, Harbourne, & Cavanaugh, 2006). …”