DIFFERENCES IN MUSCLE ACTIVITY DURING KNEELING WITH AND WITHOUT KNEELING MAT

1. DIFFERENCES IN MUSCLE ACTIVITY DURING KNEELING WITH AND WITHOUT KNEELING MAT Daniel Lomo-Tettey, Dr. Campbell-Kyureghyan Department of Industrial and Manufacturing Engineering College of Engineering and Applied Science • Motivation • Many daily occupational tasks in construction, utilities, mining and other industries involve frequent and/or prolonged kneeling. • Kneeling mats or knee pads are usually recommended for tasks that involve kneeling. • However, the effectiveness of kneeling mats/pads has not been explored in depth. • Goal • To evaluate muscle activity during static kneeling on both legs at 90° of knee flexion in two experimental conditions: with and without a kneeling mat. • It is hypothesized that kneeling on the kneeling mat will reduce muscle activity in comparison to the condition without a kneeling mat.

2. Method Figure 1: A subject kneeling on both knees at 90 of knee flexion with kneeling mat. Subjects (8) Kneeling task (Fig. 1). Randomized control trial Recorded surface electromyography (sEMG) signals (Fig. 2 and Fig. 3). Acquired sEMG signals at 2000Hz, filtered (4th order Butterworth band-pass filter, corner frequencies 20-500Hz) Calculated root mean square (RMS) amplitudes with 0.125s window size and 0.0625s overlap; normalized to the RMS value of the first minute of kneeling Calculated %difference in nRMS between kneeling mat and no kneeling mat conditions Applied paired t-test with 95% CI, statistical significance set at p < 0.05. Bilateral RA Bilateral ES **This research was approved by UWM Institutional Review Board (Protocol #13.321-UWM) ** Unilateral: SEM RF VL VM BF MG LG TA Figure 2: sEMG electrodes placed on a subject’s leg and torso muscles (posterior view). Figure 3: sEMG electrodes placed on a subject’s leg and torso muscles (anterior view).

3. Results/Conclusion • Results: • Difference between kneeling mat and no kneeling mat conditions were significant for BF (38%, p = 0.000), SEM (14%, p = 0.002), LG (9%, p = 0.006), VL (13%, p = 0.001), RRA (16%, p = 0.000), RES (30%, p = 0.008) and LES (35%, p = 0.000) (Fig. 4 - poster). • Differences in VM, MG, TA and LRA • were no statistically significant. • Explanation: The role of agonist and • antagonist knee and low-back flexors • and extensors in reducing knee • joints loading. • Discussion/Conclusion: • Reduction in muscle activity with the • kneeling mat emphasizes the importance • of cushioning the knee joints and the • flexibility of adjusting lateral and sagittal • body position during kneeling. • This finding is an important step in determining potential interventions to minimize the effects of kneeling. References: (1). Gallagher, S., et al. (2009). Journal of safety research 40, 233-237; (2). Perry, J. D., et al. (1975). Journal of bone and joint surgery 57, 961-967; (3). Porter, W. L., et al. (2010). Applied ergonomics 42, 106-113