Available online 5 December 2025

Author links open overlay panel, , , , AbstractObjective

Percent maximum voluntary contraction (%MVC) provides a normalized assessment of muscle exertion that can be compared between individuals. A higher %MVC during tasks can lead to more rapid muscle fatigue and increased risk of injury. This study evaluates the %MVC of forearm muscles while manipulating four laparoscopic energy devices and compares the differences in muscle activity between surgeons with different hand sizes.

Design

Non-experimental correlational study.

Setting

Testing was performed in a simulation lab at Mayo Clinic Arizona.

Participants

Surgeons and surgical trainees that regularly perform robotic/laparoscopic surgery.

Interventions

Demographic information, glove size, and grip strength were collected. Four advanced energy devices were assessed. Surface electromyography (sEMG) electrodes were applied to the flexor digitorum superficialis (FDS), extensor carpi ulnaris (ECU), extensor carpi radialis longus (ECR), and extensor pollicis longus (EPL) of the dominant hand. Isometric MVC was performed on each muscle. Participants performed opening, closing, and activation cycles for each instrument. EMG output was filtered and normalized to provide %MVC.

Measurements and Main Results

Twenty-four individuals participated. Fourteen were female. Glove sizes ranged from 5.5-8.5, with 6.5 being the most common (n=8). Glove size analysis was split between small (≤ 6.5) and large (>6.5).

When adjusting for training level and instrument used, FDS and ECR displayed statistically significantly higher levels of activation in the small-handed group (p= 0.0012 and 0.013, respectively). 15% MVC was selected as a cutoff for evaluation due to increased risk of muscle fatigue and injury with sustained use above this threshold. Of the 16 muscle/instrument combinations, 10 showed a mean %MVC of greater than 15% for small hands, with one combination over 15% for large hands.

Conclusion

Smaller-handed surgeons demonstrate increased forearm muscle activation when using laparoscopic instruments. Industry partners should consider variations in surgeon hand size when developing instruments to prevent disproportionate risk of injury to surgeons with smaller hands.

Introduction

Hand and wrist injury or pain secondary to laparoscopic surgery is well documented.1, 2, 3, 4, 5, 6 Smaller handed individuals in multiple specialties report more discomfort and difficulty using endoscopic and laparoscopic instruments than their peers with larger hands.7 Recent studies of quantitative differences according to hand size show increased strain and even differences in surgical performance for surgeons with smaller hands.8,9 Few studies directly evaluate the amount of muscle activity required to manipulate these instruments. The level of muscle activation required in a task is often described as a percentage of the activation seen in maximal voluntary contraction (%MVC).10 As the percentage of maximal contraction increases, muscle fatigue develops more rapidly, particularly in prolonged muscle activation. Increasing fatigue can predispose a muscle to injury.11,12 As the %MVC is a normalized variable, it can be directly compared between individuals. The goal of this study was to quantify the level of muscle activation (%MVC) required by different hand sizes while using common laparoscopic energy devices, as increasing %MVC during exertion is a known risk factor for muscle fatigue and injury.

We hypothesized that smaller handed surgeons would require higher levels of %MVC when using laparoscopic instruments compared to larger handed surgeons. Additionally, differences in cutting mechanisms, ratcheting, and overall handle size alter the movement required to manipulate a device. We therefore hypothesized that variations in required muscle activity would exist across the four instruments tested, leading to higher %MVC and risk of muscle fatigue in different areas of the forearm depending on the device.

Section snippetsMethods

Institutional review board approval was obtained through Mayo Clinic in Phoenix, Arizona (IRB 23-012348) as well as through the education review committee for inclusion of trainees. Participation was open to residents, fellows, advanced practice providers and surgeons of any specialty who regularly performed laparoscopic or robotic surgery. Regular was considered weekly for trainees on surgical rotations and bimonthly for non-trainees. Robotic and laparoscopic surgeons were considered similar

Results

Twenty-four individuals participated; their characteristics are described in Table 1. Glove size analysis was split between small (≤ 6.5) and large (>6.5) which coincided with the median glove size of 6.5 in this cohort. All participants with glove size >6.5 were male. Grip strength means by sex were 32.7 (5.4) kg for women and 52.5 (15.6) kg for men which fall within accepted normative ranges.17 Mean grip strength was 34.1kg (SD 7.8) for small-handed surgeons and 56.1kg (SD 14.5) for large

Discussion

This study identified statistically significant differences in forearm muscle activation between individuals with different hand sizes using different laparoscopic vessel sealing devices. While 15% MVC has been used as a cutoff for increased risk of muscle fatigue, recent literature suggests that a value as low as 5% can lead to muscle fatigue in under an hour of sustained contraction.16,18 All four muscles were at >15%MVC for significantly longer in the small-handed group, potentially

Conclusion

This research serves to provide objective evidence that laparoscopic devices require levels of muscle activation that may predispose surgeons with smaller hands to higher risks of muscle fatigue and injury. Future instrument design should focus on creating surgical devices that are inclusive and safe for all users.

Prior presentation

none

Funding

none

IRB approval

Study approval was obtained from the Mayo Clinic Arizona institutional review board, IRB #23-012348, 7/12/2024. A modification was approved 8/14/2025 for increase in participants.

Conflicts of interest

Johnny Yi, MD is a consultant for Intuitive Surgical. Mayo Clinic has received compensation for his consulting activities.

Acknowledgements

The authors would like to acknowledge Dr. Marco Santello and Dr. Yen-Hsun Wu of the Arizona State University School of Biological and Health Systems Engineering for their provision of the EMG equipment required to perform this study.

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© 2025 Published by Elsevier Inc. on behalf of AAGL.