Quantification of Physical Activities Simulated Exercise Therapy in Ambulatory Inpatients Using Surface Electromyogram from the Vastus Medialis

The present study aimed to assess whether surface electromyogram (sEMG) signal from the vastus medialis could be a candidate method to quantify physical activities during combined activities in ambulatory persons (ergometer exercise, treadmill walking, and squatting). In the first trial, twelve healthy men performed a graded cycle ergometer exercise at 0%, 30%, 60%, and 80% of peak oxygen consumption rate (VO 2peak ), followed by treadmill walking at 0, 2, 4, and 6 km/h for 3 min of each, and each exercise was intermitted by 3 min of rest. sEMG from the Vastus Medialis Oblique Longus (VML) was collected, and the integrated amplitude of spikes (sEMGAMP) were calculated every minute. Positive correlations were observed between ∆VO 2 and ΣsEMG AMP ; data at sampling frequency of 250Hz in both exercise types were plotted (r=0.888; P<0.0001; y=339.04x+4.0267). In the second trial, thirteen healthy participants (three women) performed the combined exercise comprising 3 min each for optimal walking (3 km/h), fast walking (5 km/h and 6 km/h for women and men, respectively), squatting, second optimal walking, and ergometer exercise at 30% VO 2peak , which were intermitted by 30 sec. Finally, they performed ergometer exercise at 100% VO 2peak for 1 min followed by 3-min cool-down (0W). Changes (∆) in VO 2 from the resting value and sEMG AMP during exercise were summed throughout the exercise period (Σ∆VO 2 and ΣsEMG AMP ). ΣΔsEMG AMP was positively correlated with ΣΔVO 2 (r=0.68, p=0.011, @250Hz). Monitoring sEMG from VML may be a candidate method for the evaluation of physical activities for exercise therapy in ambulatory persons.