Accelerations and EMG Differences Between Isocaloric High-Incline Walking and Level-Grade Jogging

High-incline walking is a popular mode of exercise and often serves as an alternative to level-grade running for improving cardiovascular fitness. This study examined the muscle activation and biomechanical differences between high-incline walking (HIW) at a 20% grade and level-grade jogging (LGJ) at matched exercise intensities. Nineteen physically inactive adults (18-31 years) participated. Participants completed two isocaloric exercise trials (HIW and LGJ), each lasting ten minutes. EMG data were obtained from eight muscles: biceps femoris (BF), gluteus maximus (GM), lateral gastrocnemius (LG), tibialis anterior (TA), vastus lateralis (VL), anterior deltoid (AD), erector spinae (ES), and soleus (SOL). Resultant accelerations on the foot and sacrum were measured using inertial measurement units (IMUs). At matched isocaloric intensities between LGJ and HIW, mean peak resultant acceleration was significantly higher in LGJ for the foot (22.14 ± 8.44 m/s²) and sacrum (27.21 ± 7.92 m/s²). Peak EMG activation was significantly greater during LGJ in TA (40.9% ± 21.4) and VL (52.6% ± 39.8). The EMG integral was significantly greater in the LGJ for the TA (13.8% ± 5.0) than during HIW. Despite being matched isocalorically, LGJ increased peak and integral muscle activation and produced higher foot and sacrum accelerations. These findings highlight HIW as a lower-impact, yet equally demanding, alternative to LGJ, with implications for exercise prescription and injury prevention.