Reduced Long-range Correlations Of Gait Cycle Relate To Declines In Physical Ability In The Elderly

Abstract

Some researchers have reported that long-range correlations in the fluctuations of gait cycle duration brake down in the elderly gait, and functional impairment of the central nervous system (CNS) has been thought to be responsible for the reduced long-range correlations. PURPOSE: To reveal the origin of deteriorated long-range correlations, we hypothesized that declines in physical ability as well as alterations in CNS were responsible for altered long-range correlations of gait in the elderly. METHODS: 15 healthy old adults aged 64–79 yr were recruited. The subjects walked around a 34.2 m oval walkway in ‘fast’ speed for six minutes. Heel contact timing of each stride was obtained from foot switches attached to the insole in both shoes. The subjects stepped on the same spot for six minutes on force platforms. Foot contact timing was measured from vertical force on the platforms. Fractal scaling exponents (?) which evaluate long-range correlations in gait and stepping were calculated with a fractal analysis method, detrended fluctuation analysis (DFA). Range of motion (ROM) of neck, waist, hip, knee, and ankle joints were measured. Isokinetic joint torque of hip, knee, and ankle joints were measured with Cybex Dynamometer. Flection and extension torques of each joint were measured. Functional reach test was used for measuring subjects' ability to maintain balance. RESULTS: Reduced α in gait was significantly (p < 0.05) correlated with reduced ROM in hip extension, knee extension, ankle external and internal rotation, and marginally correlated with reduced ROM in waist rotation (p = 0.056). Reduced α in stepping was significantly correlated with reduced ROM in neck lateroflection, hip external and internal rotation, abduction, and flection. It also significantly correlated with joint torque in knee flection and extention, and ankle dorsiflection. Reduced functional reach range was significantly correlated with reduced α in both gait and stepping. CONCLUSIONS: Deteriorated long-range correlations in both gait and stepping were correlated with declined physical abilities, and additionally, each correlated with different items of physical ability decline. The result implies a strong relationship existing between declined physical ability and deteriorated long-range correlations of gait and stepping cycle.