Impact of Asymmetrical Muscle Fatigue on Gait among College Students

Tiffany Lubrino¹, Armond Gray¹, Shannon Toy¹, Christopher De Leon¹, Mirai Manatad¹, Nathaniel Addonizio¹, Lexi Nehls¹, Amir Memarian¹ ,Christopher Hoang^1&2, Michael Shiraishi¹, Rahul Soangra^1&3

¹Crean College of Health and Behavioral Sciences, Chapman University, Orange, CA 92866

²Schmid College of Science and Technology, Chapman University, Orange, CA 92866

³Folwer School of Engineering, Chapman University, Orange, CA 92866

Introduction: Muscle fatigue is defined as the reduction in maximal force-generating capability during exercise and movement (Harkins, K., et al., 2005). When fatigued, movements are less coordinated and inefficiencies are exemplified – this can lead to extra energy consumption while walking. Gait parameters such as the vertical center of mass travel (COM) and swing time percentage can be used to quantify gait efficiency. We hypothesize that asymmetrically fatiguing lower limb extremities will impact gait parameters and result in an inefficient walking style.

Materials and Methods: This IRB-approved fatigue study consisted of eight healthy college students (age 20.5±2.2, 61.9±8.49 kg, 168.9±5.8 cm). Biodex, an isokinetic muscle testing machine, induced fatigue to 60% of maximum voluntary contraction (MVC) on the lower right extremity of the body: the gastrocnemius and anterior tibialis. Vicon, a motion capture system, was used to collect 3D data from 26 markers as subjects walked on a split-belt treadmill and gait parameters were calculated post-processing. Subjects walked normally at self-preferred speeds for 2 minutes while focused on the red ball at eye level; 3 trials were collected pre- and post- fatigue to measure temporal-spatial parameters. Analysis of swing time and vertical COM was completed using least means square.

Results and Discussion: For the vertical center of mass, there was a significant difference on the least square mean (LSM) between the pre-fatigue (986.9±19.573) and the post-fatigue (990.3±19.569, P<0.0414). This increase in the center of mass travel suggests a higher energy expenditure – a less efficient walking pattern due to fatigue. Additionally, there is a significant difference in the LSM swing time of pre-fatigue (75.132±1.0734) and that of post-fatigue (75.927±1.0730, P<0.0323). The main finding of this study is that asymmetrical fatiguing of one leg leads to the center of mass traveling more vertically and longer swing times. When fatigued, the subject is moving their center of mass a greater distance and suggests that more energy is used.

Figure 1. a) patient walking on treadmill, b) Least Square Means (LSM) on swing time, c) Least Square Means (LSM) on mean vertical center of mass

Conclusion: When the subject is in a fatigued state, the mean vertical center of mass fluctuates and the swing time percent increases, suggesting that the body adopts a less efficient walking style. The results of this study illustrate that the spatiotemporal parameters are significantly affected when a person is fatigued compared to individuals that are not fatigued. Ultimately, this experiment can benefit physical therapy research in the future because we can recognize and quantify how muscle fatigue impacts walking performance.

Tiff BMES Abstract