The effect of sensor position shifts on tensiomyographic parameters

Tensiomyography (TMG) is a non-invasive method to determine contractile parameters of skeletal muscles. Several methodological factors, however, might affect TMG results. The aim of this study was to investigate the effect of specific sensor position shifts on tensiomyographic parameters. 14 healthy males (age: 22.6 ± 1.2 years) participated in the study. TMG measurements were performed for rectus femoris (RF), gastrocnemius medialis (GM) and gastrocnemius lateralis (GL) on five sensor positions. The original sensor position (OP) was the recommended position on the muscle belly while for the shifted positions, the sensor was displaced one centimetre medially, laterally, proximally, and distally. TMG parameters measured were maximum radial displacement (Dm) and contraction time (Tc). To investigate the effect of sensor position shift, repeated-measures ANOVAs were performed. The ANOVAs revealed significant differences across the five sensor positions for RF and GM. Posthoc analysis showed significant reductions in Dm by 10 % (p = .03) and in Tc by 12 % (p = .008) in the laterally shifted sensor position for RF. For GM, Dm was significantly reduced by 20 % (p = .038) in the medially displaced sensor position. The results suggest that incorrect sensor positioning has an impact on TMG parameters, especially when incorrectly positioned in the medial-lateral direction.