Vertical computer mice and gaming: |b effect of mouse orientation on muscle activation and performance

Abstract

Introduction: Continued growth in the electronic sports industry has fuelled an increase in gaming-related pain, with 37.9% of high-level gamers reporting pain to the distal upper limb. The prevalence of gaming-related pain is not surprising when considering the high physical demands, including up to 500 actions/minute for 10 hours/day. Previous researchers investigated vertical mouse use as a means of reducing musculoskeletal load, which identified modest reductions in wrist extensor activity; however, only naïve participants with no prior experience using a vertical mouse were tested. The purpose of this study was to quantify gaming performance and physical demands in high-level gamers that received training with the vertical mouse compared to conventional horizontal mouse use. Given the sustained intensity and frequency of gaming actions and the likelihood of fatigue development, each computer mouse was tested before and immediately after a fatiguing protocol. Methods: Fifteen high-level gamers ranked in the top quartile of their preferred game were separated into 2 groups, balanced according to gameplay performance tested in the lab. One group (n=8) received a horizontal gaming mouse (Logitech G203) while the other group (n=7) received a vertical gaming mouse (Deluxe Seeker). Following an extensive 2-week training protocol, gaming performance was assessed in 3 trials before and after a fatiguing protocol within the software FirstPersonScience (v22.05.01). The fatigue protocol consisted of sustaining combined grip and wrist extension efforts at 20% of maximal voluntary force until failure. The gaming trials involved target acquisition of 16 targets spawned consecutively in random order at 2 different distances circling a homing origin in increments of 45° (azimuth). Measured performance outcomes were time to target acquisition (ms), accuracy (%), and throughput (bits/s). Amplitude probability distribution function (% maximum voluntary contraction, MVC) of seven muscles were also quantified via bi-polar surface electromyography at 4,000 Hz: abductor pollicis longus (APL), flexor carpi radialis (FCR), flexor carpi ulnaris (FCU), flexor digitorum (FD), extensor carpi radialis (ECR), extensor carpi ulnaris (ECU), and extensor digitorum (ED). Repeated measures ANOVAs tested the effects of computer mouse (horizontal, vertical), fatigue development (pre-, post-), and trial number (1, 2, 3) on all performance and muscle activity metrics (α<0.05). Muscle activity percentiles (10th, 50th, 90th, 99th) were also entered as an independent variable to represent the amplitude probability distribution function. Results: There was a significant interaction between computer mouse and pre-post fatigue on time to target acquisition (F1,13=16.16, p<0.01). Time increased following pre-post fatigue development for the vertical mouse only. Consequently, target acquisition was slower for the vertical than horizontal mouse in the post-fatigue condition. However, there were no significant findings for target accuracy or throughput between the computer mice. With respect to physical demands aggregated over all experimental conditions, muscle activity ranged from 1% MVC (10th percentile) to 5% MVC (99th percentile) across the flexors, and 2% MVC (10th percentile) to 17% MVC (99th percentile) for the extensors. This level of muscle activity indicated persistent static loading for all extensor muscles. FCU, FCR, FD, and ECR muscle activity all decreased with vertical mouse use (compared to horizontal), especially for the 90th and 99th percentiles. These changes were muscle dependent, with the greatest reductions in muscle activity for the ECR (F1,13=5.06, p=0.042; Horizontal mouse – 10.09±2.35% MVC; Vertical mouse – 6.15±2.51% MVC). Conclusion: While muscle activity decreased for the vertical mouse in 90th and 99th percentiles, there were no significant differences at the 10th percentile. Performance differences between mice were also minimal. Considering prolonged gameplay durations characteristic of high-level gamers, my results reflect increased risk of developing musculoskeletal pain and/or disorder due to persistent static loading regardless of mouse design.