Author(s): SAKAMOTO, M., KAMIDE, N., ANDO, M., SATO, H., SHIBA, Y., SHIMIZU, S., SUGAWARA, H., TADANO, C. , Institution: SCHOOL OF ALLIED HEALTH SCIENCES, KITASATO UNIVERSITY, Country: JAPAN, Abstract-ID: 570

INTRODUCTION:
The decline in neuromuscular function and loss of skeletal muscle mass associated with aging leads to a change in gait ability (Tavakkoli Oskouei et al. 2021). As an index of instantaneous muscle force development, rate of force development (RFD) indicates neuromuscular function. It has been reported that RFD of the plantar flexor (PF) muscle, analyzed by a rapid heel-raise movement on a portable force plate, contributes to walking speed (Clark et al. 2013, Hester et al. 2021). However, these studies evaluated no spatiotemporal gait parameters other than walking speed. The aim of this study was to examine the association of PF RFD, measured by the heel-raise test using a portable force plate, to spatiotemporal gait parameters in older adults.
METHODS:
The participants were 193 older adults aged 65 years and older (mean age, 74.2 ± 5.2 years, 140 females) who were living independently in the community. Maximum gait speed, step length, and cadence were recorded by a pressure-sensitive walkway system (MW-1000; Anima, Tokyo, Japan). Sampling frequency of the system was set at 100 Hz. RFD of PF was evaluated by vertical ground reaction force data measured during a rapid heel-raise task performed on a portable force plate (Clark et al. 2013, Hester et al. 2021). The vertical force data were sampled at 100 Hz and analyzed by LabChart software. In this study, RFDpeak was defined as peak force divided by the time to peak force (Hester et al. 2021), and RFD50 as force at 50 msec divided by 50 msec. As these RFD values were the mean slope of each interval, we also calculated the maximum slope value (RFDmax) during the heel-raise movement (Clark et al. 2013), analyzed by LabChart software. RFDmax was calculated from the peak of the first derivative of the force signal (Thompson et al. 2014). As a marker of muscle strength, handgrip strength was measured on a dynamometer. The associations between each gait parameter and each of RFD and handgrip strength were analyzed using multivariate regression analysis, with each gait parameter as the dependent variable and RFD and handgrip strength as the independent variable, adjusted for age and sex as confounders. Step length was normalized by height in the analysis. Significance was set at p < 0.05.
RESULTS:
Gait speed was positively related to RFDpeak (p < 0.01), RFDmax (p<0.01), and handgrip strength (p < 0.01). Step length was positively related RFDmax (p=0.014) and handgrip strength (p=0.047). Cadence was positively related to all RFD parameters of RFD50 (p=0.03), RFDpeak (p=0.02), and RFDmax (p=0.02), but not to handgrip strength.
CONCLUSION:
PF RFD measured by the heel-raise test was associated with spatiotemporal gait parameters in older adults. These results suggest an association of neuromuscular function with spatiotemporal gait parameters, and particularly with cadence.