The interaction of postural and voluntary strategies for stability in Parkinson's disease

de Lima-Pardini AC, Papegaaij S, Cohen RG, Teixeira LA, Smith BA, Horak FB. The interaction of postural and voluntary strategies for stability in Parkinson's disease. J Neurophysiol 108: 1244-1252, 2012. First published June 6, 2012; doi:10.1152/jn.00118.2012.-This study assessed the effects of stability constraints of a voluntary task on postural responses to an external perturbation in subjects with Parkinson's disease (PD) and healthy elderly participants. Eleven PD subjects and twelve control subjects were perturbed with backward surface translations while standing and performing two versions of a voluntary task: holding a tray with a cylinder placed with the flat side down [low constraint (LC)] or with the rolling, round side down [high constraint (HC)]. Participants performed alternating blocks of LC and HC trials. PD participants accomplished the voluntary task as well as control subjects, showing slower tray velocity in the HC condition compared with the LC condition. However, the latency of postural responses was longer in the HC condition only for control subjects. Control subjects presented different patterns of hip-shoulder coordination as a function of task constraint, whereas PD subjects had a relatively invariant pattern. Initiating the experiment with the HC task led to 1) decreased postural stability in PD subjects only and 2) reduced peak hip flexion in control subjects only. These results suggest that PD impairs the capacity to adapt postural responses to constraints imposed by a voluntary task.National Institute on Aging [R37-AG-006457]Brazilian National Council for Scientific and Technological Development [200321/2010-2

Balance and fear of falling in subjects with Parkinson's disease is improved after exercises with motor complexity

Resistance training with instability (RTI) uses exercises with high motor complexity that impose high postural control and cognitive demands that may be important for improving postural instability and fear of falling in subjects with Parkinson's disease (PD). Here, we hypothesized that: 1) RTI will be more effective than resistance training (RT) in improving balance (Balance Evaluation Systems Test [BESTest] and overall stability index [Biodex Balance System (R)]) and fear of falling (Falls Efficacy Scale-International [FES-I] score) of subjects with Parkinson's disease (PD)and 2) changes in BESTest and FES-I after RTI will be associated with changes in cognitive function (Montreal Cognitive Assessment [MoCA] score -previously published) induced by RTI. Thirty-nine subjects with moderate PD were randomly assigned to a nonexercising control, RT, and RTI groups. While RT and RTI groups performed progressive RT twice a week for 12 weeks, the RTI group added progressive unstable devices to increase motor complexity of the resistance exercises. There were significant group x time interactions for BESTest, overall stability index, and FES-I scores (P < 0.05). Only RTI improved BESTest, overall stability index and FES-I scores, and RTI was more effective than RT in improving biomechanical constraints and stability in gait (BESTest sections) at post-training (P < 0.05). There were strong correlations between relative changes in BESTest and MoCA (r= 0.72, P= 0.005), and FES-I and MoCA (r=-0.75, P= 0.003) after RTI. Due to the increased motor complexity in RTI, RTI is recommended for improving balance and fear of falling, which are associated with improvement in cognitive function of PD.FAPESPCAPESCNPqUniv Sao Paulo, Sch Phys Educ & Sport, Lab Neuromuscular Adaptat Strength Training, Sao Paulo, BrazilUniv Sao Paulo, Sch Arts Sci & Humanities, Sao Paulo, BrazilNorthwestern Univ, Dept Phys Therapy & Human Movement Sci, Chicago, IL 60611 USARush Univ, Med Ctr, Dept Neurol Sci, Chicago, IL 60612 USAUniv Sao Paulo, Sch Phys Educ & Sport, Exercise Hemodynam Lab, Sao Paulo, BrazilUniv Sao Paulo, Fac Med Sci, Sao Paulo, BrazilSao Paulo State Univ Rio Claro, Posture & Gait Studies Lab, Rio Claro, BrazilUniv Sao Paulo, Sch Phys Educ & Sport, Human Motor Syst Lab, Sao Paulo, BrazilUniv Sao Paulo, Dept Radiol, LIM 44, Sao Paulo, BrazilUniv Fed Sao Paulo, Ctr Psychobiol & Exercise Studies, Dept Psychobiol, Sao Paulo, BrazilUniv Fed Sao Paulo, Ctr Psychobiol & Exercise Studies, Dept Psychobiol, Sao Paulo, BrazilFAPESP: 2011/042423FAPESP: 2012/03056-4FAPESP: 2013/04970-4CAPES: 3095/2015-00CNPq: 406609/2015-2Web of Scienc