Two-dimensional spatial error distribution of key tensiomyographic parameters.

Tensiomyography detects the contraction time (Tc) and amplitude (Dm) of muscle belly thickening during maximal isometric twitch contraction. The assessment of both parameters is highly reliable; however, it seems that their calculation depends on the measurement point. The aim of the study was to determine spatial relative error distribution of Tc and/or Dm within a two-dimensional array of 27 (3 × 9) measurement points in comparison to the reference point (RP) in 12 male participants (22.5 ± 3.1 years). The RPs were determined as follows: in the biceps brachii (BB) at 50% of the humerus length; in the erector spinae (ES) at the height of the iliac crest; in the vastus lateralis (VL), vastus medalis (VM), and rectus femoris (RF) at 30%, 20%, and 50% of femur length above the patella, respectively. The surface area under the 3% relative error in Dm (BB: 4.0; VL: 3.8; VM; 8.2; RF: 6.2; ES: 2.4 cm2) was lower than in Tc (BB: 6.9; VL: 3.8; VM; 4.6; RF: 9.5; ES: 3.7 cm2), yielding merged values (BB: 3.9; VL: 3.7; VM; 4.8; RF: 5.1; ES: 2.4 cm2). Dm show twice as steep relative error rate when moving away from the RP in comparison to Tc, which seems to be less sensitive to spatial sensor positioning.