Association of muscle hardness with muscle tension dynamics: a physiological property

Abstract

This study aimed to investigate the relationship between muscle hardness and muscle tension in terms of length-tension relationship. A frog gastrocnemius muscle sample was horizontally mounted on the base plate inside a chamber and was stretched from 100 to 150% of the pre-length, in 5% increments. After each step of muscle lengthening, electrical field stimulation for induction of tetanus was applied using platinum-plate electrodes positioned on either side of the muscle submerged in Ringer's solution. The measurement of muscle hardness, i.e., applying perpendicular distortion, was performed whilst maintaining the plateau of passive and tetanic tension. The relationship between normalised tension and normalised muscle hardness was evaluated. The length-hardness diagram could be created from the modification with the length-tension diagram. It is noteworthy that muscle hardness was proportional to passive and total tension. Regression analysis revealed a significant correlation between muscle hardness and passive and total tension, with a significant positive slope (passive tension: r = 0.986, P < 0.001; total tension: r = 0.856, P < 0.001). In conclusion, our results suggest that muscle hardness depends on muscle tension in most ranges of muscle length in the length-tension diagram.

Intermuscular pressure between synergistic muscles correlates with muscle force

“…This finding coincides with the fact that muscle hardness and longitudinal stiffness increase with force generation (Morgan, 1977;Horikawa et al, 1993;Ettema and Huijing, 1994;Murayama et al, 2005Murayama et al, , 2012.…”

“…Consequently, transverse forces would be increased and IrMP would be on a higher level at the same time. Besides this context, a certain variability is even to be expected owing to the fact that muscle hardness in maximum isometric contractions is variable as well (Murayama et al, 2012). Muscle hardness in turn is strongly affected by IaMP (Steinberg and Gelbermann, 1994;Steinberg, 2005), which is more variable as compared with muscle force throughout the entire isometric lengthtension relationship (Ward et al, 2007;Winters et al, 2009).…”

“…(3) Also, muscle hardness, i.e. the resistance offered by the muscle against perpendicular pressure, considerably increases with rising force during contraction (Horikawa et al, 1993;Murayama et al, 2005Murayama et al, , 2012. On the basis of these facts, the following simple explanatory approach is suggested (Fig.…”

Noncontact human force capturing based on surface hardness measurement

“…It has been confirmed that the muscle hardness is proportional to the muscle tension over a wide range [9]. Therefore the muscle hardness can be an index of the force generated by the muscle contraction.…”

Muscle hardness and masticatory myofascial pain: Assessment and clinical relevance

“…In this context, the impression of muscle tightness or increased muscle hardness in painful muscles is commonly reported in the clinical practice . Muscle hardness could be defined as the amount of displacement resistance when perpendicular pressure is applied to the muscle, and it is has been associated with an “increased muscle tension” and muscle pathology .…”