Effect of 8-week Frequency-specific Electrical Muscle Stimulation Combined With Resistance Exercise Training on Muscle Mass, Strength, and Body Composition in Men and Women: A Feasibility and Safety Study

The Countermovement Jump (CMJ) Test

时间窗: up to 8 weeks

The CMJ test is a practical, effective, reliable, and simple method of measuring lower limb strength, which is related to the maximum speed, strength and explosive force of the lower limbs. For this test, participants stood on the Kistler force measurement platform (9260AA, Kistler Co., Ltd., Switzerland) on both feet and performed to inspection. During the test, they were asked to put their hands on their hips and remain on the platform. After that, they were asked to squat down until the knees bent 90 degrees and then to immediately jump as high as possible. The average power (MF), were recorded during the jump. Each participant repeated the test 3 times, and CMJ data were obtained at the designated points. The instrument was calibrated for each individual's weight.

Clinical Biochemistry of glucose level

时间窗: After 8 weeks of EMS

For assessment of fatigue-related indices, volunteers fasted for at least 8 h before the 60% VO2max fixed intensity exercise challenge. Blood samples were collected with an arm venous catheter at indicated time points during exercise and recovery periods, including baseline (0), 30 (E30) min during the exercise phase, and 60 (R60) min in the recovery phase. Serum glucose (mg/dL), were assessed for monitoring physiological adaptation. All biochemical indices were assessed using an autoanalyzer (Hitachi 7060, Tokyo, Japan).

VO2max

时间窗: After 8 weeks of EMS

To evaluate the maximum oxygen consumption and exercise performance, we used a treadmill (Pulsar, h/p/cosmos, Nussdorf-Traunstein, Germany) and an automatic breathing analyzer (Vmax 29c, Sensor Medics, Yorba Linda, CA, USA). In addition, a polar heart rate device was used to monitor the heart rate (HR). The speed range of the treadmill was set to 7.2 km/h and increased by 1.8 km/h every 2 min until fatigue, according to Bruce's protocol. When the breathing exchange rate (the volume ratio of carbon dioxide produced to oxygen consumed, VCO2/VO2) was higher than 1.10 and reached the maximum heart rate (maximum heart rate = 220 - age), oxygen consumption was considered to be maximum. The three highest VO2max peak were averaged to obtain the VO2max values of the individual volunteers.

Body composition_body fat

时间窗: up to 8 weeks

The multi-frequency principle was applied to measure body composition by using a bioelectrical impedance analyzer (BIA) on an InBody 570 device (In-body, Seoul, South Korea). To perform the measurements, after the subjects' palms and soles were removed from the sensors, the subjects stood on the footing electrodes and held the sensing handles with two hands. During the measurements, the subjects kept their arms open and left their bodies at an angle of 30° without speaking or moving. The subjects also fasted for at least 8 h before the test. The body fat were meansure

Grip strength

时间窗: up to 8 weeks

Use the armed grip machine (T.K.K.5401, Takei Scientific Instruments Co.,Ltd, Niigata, Japan) to measure, hold each of the left and right hands three times until they are weak, and record the maximum value

Clinical Biochemistry of ammonia level

时间窗: After 8 weeks of EMS

For assessment of fatigue-related indices, volunteers fasted for at least 8 h before the 60% VO2max fixed intensity exercise challenge. Blood samples were collected with an arm venous catheter at indicated time points during exercise and recovery periods, including baseline (0), 30 (E30) min during the exercise phase, and 60 (R60) min in the recovery phase. Serum ammonia (umol/L), were assessed for monitoring physiological adaptation. All biochemical indices were assessed using an autoanalyzer (Hitachi 7060, Tokyo, Japan).

Body composition_muscle mass

时间窗: up to 8 weeks

The multi-frequency principle was applied to measure body composition by using a bioelectrical impedance analyzer (BIA) on an InBody 570 device (In-body, Seoul, South Korea). To perform the measurements, after the subjects' palms and soles were removed from the sensors, the subjects stood on the footing electrodes and held the sensing handles with two hands. During the measurements, the subjects kept their arms open and left their bodies at an angle of 30° without speaking or moving. The subjects also fasted for at least 8 h before the test. The muscle mass were meansure

Clinical Biochemistry of lactate level

时间窗: After 8 weeks of EMS

For assessment of fatigue-related indices, volunteers fasted for at least 8 h before the 60% VO2max fixed intensity exercise challenge. Blood samples were collected with an arm venous catheter at indicated time points during exercise and recovery periods, including baseline (0), 30 (E30) min during the exercise phase, and 60 (R60) min in the recovery phase. Serum lactate (mmol/L), were assessed for monitoring physiological adaptation. All biochemical indices were assessed using an autoanalyzer (Hitachi 7060, Tokyo, Japan).