Graduation Date

Fall 2023

Document Type

Thesis

Program

Master of Science degree with a major in Kinesiology, option Exercise Science

Committee Chair Name

Dr. Eli Lankford

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Dr. Justus Ortega

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Dr. Tina Manos

Third Committee Member Affiliation

HSU Faculty or Staff

Subject Categories

Kinesiology

Abstract

Treadmills are widely used in biomechanical research. However, variations in treadmill design and running surfaces may affect biomechanical variables such as muscle activation and impact acceleration. In addition, incline walking on treadmills leads to changes in the pattern of muscle activation, particularly at steeper inclines. Despite extensive research on the effects of running surfaces and inclines on biomechanical variables (gait, muscle activation, impact force), the impact of varying treadmill manufacturers on biomechanical variables at high inclines remains unclear. Purpose: To determine whether the type of treadmill deck influences surface electromyography (EMG) patterns and impact accelerations at high incline (20%) walking (HIW) and low incline (1%) jogging (LIJ) with the same rating of perceived exertion. Methods: 15 males and 7 females, age (27.8±7.7yrs), engaged in two sessions of HIW and two sessions of LIJ on two cushioned treadmills (TM1 and TM2) at a self-selected pace corresponding to pre-established perceived exertion rating of 11. Each session lasted 5-minutes in duration. EMG markers were placed over the Tibialis Anterior (TA), Soleus (SOL), Lateral Gastrocnemius (LG), Biceps Femoris (BF), Gluteus Maximus (GM), Anterior Deltoid (AD), Vastus Lateralis (VL), and the Erector Spinae (ES). Trident Inertial Measurement Units (IMU) were attached to the dorsal aspect of the foot (top) and sacrum (lower back). EMG activity, impact accelerations, heart rate, and RPE were collected at the 4-minute 30-seconds mark only. Result/Discussion: Peak EMG for LG (p=0.005), SOL (p=0.010), and BF (p<0.001) displayed significant differences on TM1 63.6±27.0%, 106.2±72.3%, and 39.1±28.5% respectively, compared to 55.7±22.4%, 94.5±70.4%, and 31.2±21.1% on TM2. However, AD exhibited lower peak activation during HIW on TM2 at 2.6±1.8% compared to LIJ on TM2 at 4.1±2.3% (p=0.010). The integral EMG activity of AD, BF, ES, VL, SOL, LG, and GM on TM1 increased by 1.9±1.0%, 21.7±14.4%, 20.3±11.1%, 25.7±12.7%, 59.2±38.8%, 33.6±13.5%, and 19.8±8.5%, respectively, during HIW compared to LIJ at 1.3±0.6%, 13.3±6.7%, 12.1±8.1%, 19.8±7.3%, 39.5±22.8%, 24.2±9.4%, and 11.7±6.4%. The integral EMG activity of AD, ES, VL, SOL, LG, and GM on TM2 increased by 2.1±1.4%, 19.4±9.9%, 26.0±13.7%, 55.0±40.0%, 30.5±11.5%, and 18.5±7.4%, respectively, during HIW compared to LIJ at 1.5±0.8%, 11.9±9.2%, 20.1±9.1%, 38.8±21.3%, 24.6±8.6%, and 12.6±8.7%. However, only the integral EMG activation of BF and LG differed between TM1 and TM2 during HIW, indicating increased integral EMG activation on TM1 at 21.7±14.4% and 33.6±13.5% compared with TM2 at 18.5±11.3% and 30.5±11.5%. The foot's resultant acceleration was notably lower during High-Incline Walking (HIW) on both TM1 (12.16±5.43m/s²) and TM2 (10.62±4.28m/s²) compared to Low-Incline Jogging (LIJ) on TM1 (25.31±14.89m/s²) and TM2 (25.75±11.29m/s²), respectively. Likewise, the sacrum's resultant acceleration exhibited a decrease on TM1 (14.26±2.27m/s²) and TM2 (13.76±2.04m/s²) during HIW compared to LIJ on TM1 (37.46±14.61m/s²) and TM2 (37.49±12.18m/s²), respectively. Regarding HR, there was no difference between TM1 (162.7±24.3 bpm) and TM2 (160.5±21.8bpm) at LIJ, but there was a significant difference between TM1 (171.2±24.8bpm) and TM2 (164.62±23.7 bpm) at HIW. The rating of perceived exertion also differed between TM1 (13.96±1.96) and TM2 (13.09±1.97) during HIW (p=.005). Conclusion: Our investigation revealed that at the same speed and grade, treadmill design may impact the peak and integral muscle EMG patterns, RPE, and HR responses during HIW. Regardless of the treadmill design, impact accelerations of the foot and sacrum decreased as the grade increased from 1% to 20%. These results suggest that caution should be taken when extrapolating biomechanical and physiological results from one treadmill to another.

Citation Style

APA

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