Abstract
It is well-known that unusual exercise, especially eccentric contraction (ECC), could cause delayed-onset muscle soreness. However, the factors related to the loss of muscle strength and range of motion (ROM) caused by eccentrically damaged muscle, such as increases in muscle soreness, tissue hardness, and pain threshold, have not been investigated in detail. Thus, this study was conducted to investigate the factors related to the loss of muscle strength and ROM caused by eccentrically damaged muscle in a large sample. Fifty-six sedentary healthy young male volunteers were instructed to perform 60 repetitions of ECC exercise. The outcome variables were measured before and 48 h after the ECC exercise. The results showed that a decrease in ROM was correlated to an increase in tissue hardness, whereas a decrease in muscle strength was correlated to an increase in muscle soreness. Our results suggested that tissue hardness must be controlled for ROM loss, and muscle soreness must be controlled for muscle-strength loss.
Highlights
It is well-known that unusual exercise, especially eccentric contraction (ECC), could cause muscle damage
Pearson’s product–moment correlation coefficient showed that there was a significant correlation between ∆knee flexion range of motion (ROM) and ∆tissue hardness (r = −0.314, p = 0.019, Figure 2A), but there were no significant correlations between ∆pain pressure threshold (PPT) (r = 0.131, p = 0.341, Figure 2B), ∆muscle soreness at stretching (r = 0.104, p = 0.448, Figure 2C), and muscle soreness at palpation (r = −0.21, p = 0.125, Figure 3D)
This study showed that the decrease in ROM caused by ECC exercise was associated with an increase in tissue hardness, and the decrease in muscle strength was associated with muscle soreness
Summary
It is well-known that unusual exercise, especially eccentric contraction (ECC), could cause muscle damage. It is a condition characterized by transient ultrastructural myofibrillar disruption, muscle-strength loss, delayed-onset muscle soreness (DOMS), swelling, reduced range of motion (ROM), systemic efflux of myocellular enzymes, and proteins [1,2]. Nosaka et al (2006) suggested that maximal voluntary isometric contraction (MVC-ISO) loss after ECC exercise does not correlate strongly with changes in markers of muscle damage (i.e., ROM, swelling, and muscle soreness) [6]. Dames et al (2016) investigated the response of markers (i.e., ROM, swelling, CK activity, and muscle soreness) among a large number of young men (N = 286) They suggested that MVC-ISO loss could reflect the indirect maker for muscle damage [7]. The changes in MVC-ISO and RFD after ECC exercise are sensitive indirect markers for muscle damage induced by ECC exercise
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