Assessment of neuromuscular function after different strength training protocols using tensiomyography

The purpose of the study was to analyze tensiomyography (TMG) sensitivity to changes in muscle force and neuromuscular function of the muscle rectus femoris (RF) using TMG muscle properties after 5 different lower-limb strength training protocols (multiple sets; DS = drop sets; eccentric overload; FW = flywheel; PL = plyometrics). After baseline measurements, 14 male strength trained athletes completed 1 squat training protocol per week over a 5-week period in a randomized controlled order. Maximal voluntary isometric contraction (MVIC), TMG measurements of maximal radial displacement of the muscle belly (Dm), contraction time between 10 and 90% of Dm (Tc), and mean muscle contraction velocities from the beginning until 10% (V10) and 90% of Dm (V90) were analyzed up to 0.5 (post-train), 24 (post-24), and 48 hours (post-48) after the training interventions. Significant analysis of variance main effects for measurement points were found for all TMG contractile properties and MVIC (p < 0.01). Dm and V10 post-train values were significantly lower after protocols DS and FW compared with protocol PL (p = 0.032 and 0.012, respectively). Dm, V10, and V90 decrements correlated significantly to the decreases in MVIC (r = 0.64-0.67, p ≤ 0.05). Some TMG muscle properties are sensitive to changes in muscle force, and different lower-limb strength training protocols lead to changes in neuromuscular function of RF. In addition, those protocols involving high and eccentric load and a high total time under tension may induce higher changes in TMG muscle properties.