Modulation of Plantar Pressure and Muscle During Gait

Introduction

Modulation of plantar pressure and muscle during gait was acquired to investigate the influences of electrical stimulation (ES) of the tibialis anterior (TA) on plantar pressure and the gastrocnemius medialis (GM) activity during gait in healthy adults. The database consists of plantar pressure distribution and two muscles activity during gait from 20 healthy male adults. We evaluated the activities of gastrocnemius medialis and lateralis during gait in the preliminary study, and observed that gastrocnemius medialis is more sensitive to gait. Therefore, we recorded GM and TA in this study. Only subjects who do not have any history of either neurological or orthopedic impairments were included..

Data Collection

The study procedure was as follows. All subjects were instructed to refrain from alcohol and strenuous activity for 24 hours prior to the experiments. ES was applied to the TA of the subjects for 30 minutes, while they were positioned sitting on the bed. First, we applied passive force until firm resistance to further movement was encountered, and then we measured ankle dorsiflexion range of motion (ROM) with knee full extension and 90° flexion using a hand-held goniometer. We measured the ankle dorsiflexion ROM, and subjects were directed to walk 10 m four times at a comfortable speed to measure plantar pressure and muscle activity during gait before and after ES. The ES procedure was as follows. Subjects' TAs were stimulated using an electrical stimulation device (ES-360, ITO CO., Tokyo, Japan) set at 50 Hz with pulse duration of 300 μsec. Stimulating electrodes (PALS Platinum M size, each about 5 cm long by 5 cm wide; Axelgaard Manufacturing Co., Fallbrook, CA, USA) were placed proximally and distally over the motor point of the TA muscles. In addition, we measured the dorsiflexion ROM per five minutes during ES, and regulated the stimulus intensity to keep the angle within -5° from the maximum dorsiflexion ROM.

The plantar pressure data consist of peak plantar pressure (PP) and pressure time integral (PTI). PP and PTI were recorded as follows. Plantar pressure distribution was recorded using an F-scan in-shoe pressure measurement system (NITTA Co., Osaka, Japan) at 50 Hz during gait. We fixed sensor seats on the subjects’ plantar surfaces using extensibility tape and socks to minimize the slip of sensor. Calibration was performed using the patient's body weight, and with one leg standing on the sensor. According to the method of Sartor et al.[2], the plantar surface was divided into three areas: the rear foot, midfoot, and forefoot. PP and PTI were calculated for four areas (rear foot, midfoot, forefoot and total plantar surface).

The muscle activities during gait were recorded as electromyography (EMG). The recording procedure was as follows. EMG activities were recorded from the right GM and TA using a two-channel data logger (Feedback Logger, DKH, Tokyo, Japan) and surface EMG sensor (SX230-1000, Biometrics Ltd, Newport., UK) at 1,000 Hz. The surface EMG sensors were placed according to the method that the SENIAM (Surface ElectroMyoGraphy for the Non-Invasive Assessment of Muscles) project recommends. The load switch system was attached on the heel as a foot switch for determining heel strike (HS), and the signals from the load switch system and F-scan system at HS had to be synchronized between plantar pressure data and EMG data.

Based on the method of Nagai et al.[1], the EMG activities from GM and TA during maximum isometric contraction were recorded via maximum isometric dorsiflexion of the ankle with the subject sitting on the chair and maximum isometric plantar flexion with the patient in single leg stance, respectively. From these, we calculated the integrated electromyogram (IEMG). Root mean square (RMS) using a 50-msec window was calculated during stance phase of the gait cycle. Muscle activity onset, duration and cessation were determined using the threshold of 10% of maximum amplitude per gait cycle, which can detect the small activity of muscles during gait, excluding the artifact of baseline. Active time, onset time, peak time and cessation time were determined based on RMS wave. IEMG was shown as a percentage of the IEMG at maximum isometric contraction (%IEMG). Onset time, peak time, active time, and cessation time were reported separately as a percentage of the stance time.

Files

Each data is identified by the name of the data (P; plantar pressure, E; EMG) followed by an arbitrary ID number and the name of trial.

Within the plantar pressure (P_) files, the contents are: in column 1, Start (the moment at which any sensor in each foot area reacted). In column 2, End (the moment all sensors that were detecting pressure in each foot area ceased to). In column 3, Contact duration (the duration from start to end). In column 4, Peak pressure. In column 5, Pressure time integral.

Within the EMG (E_) files, the contents are: in column 1, Time (Time series). In column 2, Tibialis anterior (the raw data of TA during 1 trial of 10 m walking). In column 3, Gastrocnemius medialis (the raw data of TA during 1 trial of 10 m walking).

A separate file (Summary sheet.txt) includes clinical information for each subject, including age, gender, height, weight and gait parameters (walking speed, number of steps, stride length, time of stance-phase and time of swing-phase).

References

1. Nagai K, Yamada M, Uemura K, Mori S, Aoyama T, Ichihashi N, et al. Effect of Repetitive Postural Control Exercise on Muscular Coactivation at the Ankle Joint. J Jpn Phys Ther Assoc. 2011;38(2);84–9.
2. Sartor CD, Hasue RH, Cacciari LP, Butugan MK, Watari R, Pássaro AC, et al. Effects of strengthening, stretching and functional training on foot function in patients with diabetic neuropathy: results of a randomized controlled trial. BMC Musculoskelet Disord. 2014 Apr 27;15:137. pmid:24767584