Musculoskeletal injuries (MSI) are prevalent among gastrointestinal (GI) endoscopists due to prolonged static postures during procedures such as endoscopic submucosal dissection (ESD). Maintaining such postures and repetitive movements with the endoscope increases muscle strain and fatigue, particularly in the upper limbs and back. We have previously reported that lighter endoscopes may mitigate these risks by reducing muscle activation and fatigue. Single-use endoscopes, being lighter than reusable ones, could therefore benefit endoscopists during lengthy procedures like ESD. This study aimed to compare muscle activation when using single-use versus reusable gastroscopes during simulated ESD procedures.

Ten experienced endoscopists (one female; age 37±6 years; experience 9±6 years) performed simulated ESDs using a single-use and a reusable gastroscope in an ESD-training model (G-Master). G-Master was employed to standardize task conditions among participants. Participants performed four ESD tasks (10-minute easy and a 20-minute complex ESD task using both gastroscopes) in randomized order, with a 15-minute break between scopes and a 2-minute interval between tasks for model setup. Muscle activity was recorded during the simulated ESDs using a validated ErgoShirt (Myontec) equipped with surface electromyography (sEMG) sensors measuring activation of major upper body muscles. To calibrate the sEMG sensors, the maximal voluntary contraction (MVC) was carried out by performing two sets of specific movements, for a minimum of five seconds each muscle. After performing each of the four simulated ESDs, the rate of perceived exertion (RPE) was verbally expressed by the participant to quantify exercise intensity using the Borg scale ranging between 6 and 20 (Borg, 1998) . sEMG data were analyzed using Muscle Monitor Software (Myontec) and processed in MATLAB (MathWorks) to calculate muscle load (%MVC) as the normalized percentage of each muscle’s MVC. Muscle load was categorized into five threshold zones (rest, healthy load, overload, high overload, and at-risk) based on magnitude and risk, as defined by the ErgoLink software linked to the ErgoShirt system. Data was reported using the mean and standard deviation, and analyzed using paired t-tests, with statistical significance set at P<0.05.

The RPE was 12 ± 2 (“light” to “somewhat hard”) for the easy task with both gastroscopes. During the complex task, the RPE increased to 13 ± 2 (“somewhat hard”) with the single-use gastroscope and 14 ± 1 (“somewhat hard” to “hard”) with the reusable gastroscope. The single-use gastroscope showed a statistically significant reduction in RPE during the complex task (p < 0.05), but not in the easy task. sEMG data from the right arm were excluded due to interference from high-frequency instruments, and data from the trunk muscles were unavailable because of undershirt wore by the participatns or calibration issues. Among the recorded muscles, significant differences were found only in the triceps and biceps, both showing lower average %MVC values when using the single-use gastroscope, particularly in the triceps during both tasks and in the biceps during the easy task (p < 0.05). The left wrist flexors and biceps spent a higher proportion of time in the “rest” and “healthy load” zones with the single-use device compared to the reusable one (easy: 71% vs. 65%; complex: 69% vs. 57%). Triceps and deltoids remained mostly in the healthy range for all conditions. Significant positive correlations were observed between RPE and the %MVC of triceps and deltoids. Muscle activation over time revealed greater wrist flexor overload in the second half of tasks for both scopes, indicating progressive fatigue.

This study is the first to quantify muscle load during simulated ESD using wearable surface electromyography. The single-use gastroscope was associated with a significantly lower rating of perceived exertion during complex tasks, indicating a potential ergonomic advantage under prolonged procedural conditions. Among all monitored muscles, only the triceps and biceps showed statistically differences between the two gastroscopes, with consistently lower triceps activation when using the single-use endoscope. In conclusion, the use of lightweight gastroscopes may alleviate physical strain during lengthy or complex procedures, thereby contributing to the prevention of work-related musculoskeletal injuries.