Testing the Validity and Reliability of Electromyography Acquisition Capabilities of a Wearable EMG Device, Sense3, by Strive

There is a growing demand in the sports world for wearable technology, particularly those with electromyography acquisition capabilities. Electromyography (EMG) is technique for measuring the electrical activity that occurs during muscle contraction and relaxation. Basic practical applications of EMG use in sports include, but are not limited to: measuring activation timing of a muscle, measuring levels of activation, and detecting fatigue. The sports performance company Strive has designed an EMG wearable, called Sense3, that targets the following muscles of the lower limb: Quadriceps, Hamstrings, and Glutes. Sense3 must pass reliability assays to determine the validity of the EMG system in order for Sense3 to be accessible as a commercialized product. This study was designed to compare the EMG acquisition performance of Sense3 to the performance of a traditional EMG acquisition device, MA-300, during slow and controlled movements, simulated by use of a dynamometer, and during dynamic movements. Statistics from the reliability assays showed Sense3 to be reliable in the Rectus Femoris and Biceps Femoris during dynamometer trials. Sense3 was unable to consistently record useable EMG signals for analysis during dynamic exercise trials. The ability to record EMG signals during dynamic movement was the main determinant for validity of Sense3’s EMG acquisition system. The results suggest that Sense3 is not a valid EMG acquisition system for sports-based, dynamic use

On the Detection of High-Quality, High-Density Electromyograms During 80m Sprints: a Case Study

Surface electromyograms (EMGs) have been often used to study muscle function in locomotor activities. Typically, EMGs are sampled with a single pair of electrodes, providing information on the timing and degree of muscle excitation. Additional information may be obtained when sampling EMGs with multiple electrodes from the same, target muscles. Studies using high-density EMGs (HD-EMGs) in locomotor activities are limited to laboratory settings and low speed tasks, likely due to the technical shortcomings in the commercially available systems for high-density recordings. This issue is further aggravated when kinematics data are necessary for associating EMGs with events of interest during the movement cycle. By combining two systems, ad hoc developed for the on-field recording of kinematics data and HD-EMGs, here we present single-case results during extreme-speed locomotion-the 80 m sprint on an official, athletic track. Our aim was to verify whether descriptors of quality documented in the EMG literature during well-controlled, isometric contractions, apply to the HD-EMGs we detected and segmented with respect to the running cycles. From a single, elite sprinter, we were able to obtain HD-EMGs with negligible movement artifacts and with temporal profiles typically characterizing action potentials of single motor units. Our results would seem to advocate the possibility of using HD-EMG to study muscle function during highly dynamic contractions outside the laboratory settings

Fat mass limits lower-extremity relative strength and maximal walking performance in older women

The purpose of this study was to determine if excess fat negatively affects relative strength and walking gait performance in overweight, older women. Twenty five older women (65 – 80 yr) were separated into normal weight (BMI \u3c 25 kg m−2 , n=11) and overweight groups (BMI ≥ 25 kg m−2 , n=14). Strength and rate of torque development (RTD) of the knee extensors and flexors, ankle plantarflexors and dorsiflexors were measured. Participants walked at standard and maximal speeds during which muscle activation, spatiotemporal and kinetic gait variables were measured. Relative to mass, overweight older women had 24% lower maximal torque and 38% lower RTD than normal weight women. Maximal walking speed was slower in overweight (1.25 ± 0.22 m s−1 vs. 1.54 ± 0.25 m s−1 , P = 0.004) and was correlated to strength (r = 0.53, P \u3c 0.01) and fat mass (r = −0.65, P = 0.001). At maximal speed, overweight had 11% lower vertical ground reaction force relative to mass, 8% slower stride rate, 12% shorter strides, 13% longer foot-ground contact times, 21% longer double-limb support times, 65% greater knee extensor and 78% greater plantarflexor activation (P \u3c 0.05). Overweight, older women demonstrated altered gait and reduced walking performance related to poor relative strength and rate of torque development of lower-extremity muscles

Applications of EMG in Clinical and Sports Medicine

This second of two volumes on EMG (Electromyography) covers a wide range of clinical applications, as a complement to the methods discussed in volume 1. Topics range from gait and vibration analysis, through posture and falls prevention, to biofeedback in the treatment of neurologic swallowing impairment. The volume includes sections on back care, sports and performance medicine, gynecology/urology and orofacial function. Authors describe the procedures for their experimental studies with detailed and clear illustrations and references to the literature. The limitations of SEMG measures and methods for careful analysis are discussed. This broad compilation of articles discussing the use of EMG in both clinical and research applications demonstrates the utility of the method as a tool in a wide variety of disciplines and clinical fields