Combining Resting Blood Flow Restriction with Neuromuscular Electrical Stimulation: Effects on Blood Lactate Levels and Lower Limb Muscle Function

The study participants were instructed to rest quietly in a seated position for 10 minutes. During the last 3 minutes of the resting period, upper arm blood pressure was measured twice using an automatic blood pressure monitor (BP170, InBody, Korea). The blood flow restriction cuffs (BFR Therapy Cuff, BFR Therapy Co., USA) - measuring 5cm in width and 60cm in length - were applied to the upper third of the thigh on both legs. To maintain consistency in measurements, the distance from the proximal part of the kneecap to the distal edge of the cuff was measured. A Capillary Reaction Time (CRT) test was used to assess the appropriateness of the cuff pressure; this involved applying thumb pressure to the quadriceps muscle after cuff application and timing how long it took for the skin color to return to normal.

Neuromuscular Electrical Stimulation (NMES) was applied five times a week for one week using a four-channel stimulator (Compex Physio, Chattanooga, Switzerland). The stimulation protocol was set to a frequency of 35Hz, with electrodes attached to the vastus lateralis and vastus medialis muscles. The therapist adjusted the intensity and alternating output of the electrodes selectively to facilitate the squat exercises required during the intervention. During the stimulation period, participants were engaged in a squat exercise program, with the total duration of stimulation being 10 minutes.

In this study, the squat exercise was performed in four sets. Participants were instructed to position their feet shoulder-width apart and educated to squat in such a way that their knees did not extend beyond their toes. To ensure consistency in performing the squat at the same angle, a mark was made on the wall at the pelvic height during a 90° squat. This allowed participants to perform squats at the same height. The exercise was conducted under the guidance of a physical therapist with five years of clinical experience.