Spinal flexibility and balance control among community-dwelling adults with and without Parkinson's disease

One area of research that requires further elaboration is the relationship between impairments and functional limitations. By identifying specific contributors to functional limitations, it may be possible to establish intervention strategies, including exercise approaches, that can delay or ameliorate decline in function. The association between impaired spinal flexibility and functional limitations has not been studied in depth. The purposes of this study were to determine (a) the associations between spinal flexibility and functional limitations; (b) the relative contribution of spinal flexibility to specific functional limitations; and (c) how disease state (Parkinson's disease [PD] vs no PD) modified these relationships.

Participants included 251 community-dwelling adults, 56 of whom were with diagnosed PD and 195 were without PD or other specific disorders. Measures included spinal flexibility (i.e., functional axial rotation [FAR]) and configuration (i.e., thoracic kyphosis and lumbar lordosis), functional limitations (i.e., functional reach, supine-to-stand time, 10-m walk, and 360 degrees turn).

Canonical correlation (Can R) demonstrated significant associations between spinal measures and functional limitations (Can R = .488, p = .0001). After controlling for age, gender, race, body mass index, comorbidity, confidence, and depression, a multivariate regression model demonstrated that spinal flexibility contributed significantly to functional reach (R2 = .334 for the overall model, p = .0001). Based on the parameter estimate of 0.026, the results prediet that FAR accounts for a 4.6-inch difference in reach distance between the least and most flexible of the participants. In addition, there were significant differences between almost all measurements for the PD compared with the non-PD participants.

Results clearly implicate spinal flexibility as a contributor to functional reach, a measure of functional limitation and an established measure of balance control. Further work is needed to determine the extent to which spinal flexibility can be improved and the effect of that improvement on balance.