Article

Time-course effect of exercise-induced muscle damage on localized muscle mechanical properties assessed using elastography

Acta Physiologica (Impact Factor: 4.38). 03/2014; 211(1):135-146. DOI: 10.1111/apha.12272
Source: PubMed

ABSTRACT

Changes in muscle stiffness after exercise-induced muscle damage have been classically inferred from passive torque-angle curves. Elastographic techniques can be used to estimate the shear modulus of a localized muscular area. This study aimed to quantify the changes in shear elastic modulus in different regions of the elbow flexors after eccentric exercise and their relation to muscle length.
Shear elastic modulus and transverse relaxation time (T2 ) were measured in the biceps brachii and brachialis muscles of sixteen participants, before, 1h, 48h and 21 days after 3 sets of 10 maximal isokinetic eccentric contractions performed at 120°.s(-1) .
The shear elastic modulus of the elbow flexors significantly increased 1h (+46%; P=0.005), with no significant change at 48h and 21D, post-exercise. In contrast, T2 was not modified at 1h but significantly increased at 48h (+15%; P<0.05). The increase in shear elastic modulus was more pronounced at long muscle lengths, and reached a similar extent in the different regions of the elbow flexors. The normalized hysteresis area of shear elastic modulus-length relationship for the biceps brachii increased 1h post-exercise (31%) in comparison to the pre-exercise value (18%), but was not significantly altered after five stretching cycles (P=0.63).
Our results show homogeneous changes in muscle shear elastic modulus within and between elbow flexors. The greater increase in shear elastic modulus observed at long muscle lengths suggest the putative involvement of both cross-bridges number and titin in the modifications of muscle shear elastic modulus after damaging exercise. This article is protected by copyright. All rights reserved.

Download full-text

Full-text

Available from: Gaël Guilhem, Apr 02, 2014
  • Source
    • "In the present study, GM muscle was considered as a surrogate of the behaviour of the plantar flexor muscles (Hauraix et al. 2013). Although there is currently no method validated to quantify the amount of damage in each muscle of a group, a recent study suggests that early increases in muscle shear modulus after exercise could reflect the perturbation of calcium homeostasis induced by cytoskeletal alterations (Lacourpaille et al. 2014). In addition, recent pilot analyses led by our group tend to show that this increase in shear modulus is strongly related to the MVC torque decrease 48 h post-exercise. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Aim: Defining the origins of muscle injury has important rehabilitation and exercise applications. However, current knowledge of muscle damage mechanics in human remains unclear in vivo. This study aimed to determine the relationships between muscle-tendon unit mechanics during maximal eccentric contractions and the extent of subsequent functional impairments induced by muscle damage. Methods: The length of the muscle-tendon unit, fascicles, and tendinous tissues was continuously measured on the gastrocnemius medialis using ultrasonography, in time with torque, during 10 sets of 30 maximal eccentric contractions of plantar flexors at 45°.s-1, in seventeen participants. Results: Muscle-tendon unit, fascicles and tendinous tissues were stretched up to 4.44 ± 0.33 cm, 2.31 ± 0.64 cm and 1.92 ± 0.61 cm, respectively. Fascicle stretch length, lengthening amplitude and negative fascicle work beyond slack length were significantly correlated to the force decrease 48 h post-exercise (r=0.51, 0.47, and 0.68, respectively; P < 0.05). Conclusions: The present study demonstrates that the strain applied to human muscle fibers during eccentric contractions strongly influences the magnitude of muscle damage in vivo. Achilles tendon compliance decreases the amount of strain while architectural gear ratio may moderately contribute to attenuating muscle fascicle lengthening and hence muscle damage. Further studies are necessary to explore the impact of various types of task to fully understand the contribution of muscle-tendon interactions during active lengthening to muscle damage.
    Full-text · Article · Jan 2016 · Acta Physiologica
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Isometric contractions induced by neuromuscular electrostimulation (NMES) have been shown to result in a prolonged force decrease but the time course of the potential central and peripheral factors have never been investigated. This study examined the specific time course of central and peripheral factors after isometric NMES-induced muscle damage. Twenty-five young healthy men were subjected to an NMES exercise consisting of 40 contractions for both legs. Changes in maximal voluntary contraction force of the knee extensors (MVC), peak evoked force during double stimulations at 10 Hz (Db10) and 100 Hz (Db100), its ratio (10∶100), voluntary activation, muscle soreness and plasma creatine kinase activity were assessed before, immediately after and throughout four days after NMES session. Changes in knee extensors volume and T2 relaxation time were also assessed at two (D2) and four (D4) days post-exercise. MVC decreased by 29% immediately after NMES session and was still 19% lower than the baseline value at D4. The decrease in Db10 was higher than in Db100 immediately and one day post-exercise resulting in a decrease (−12%) in the 10∶100 ratio. On the contrary, voluntary activation significantly decreased at D2 (−5%) and was still depressed at D4 (−5%). Muscle soreness and plasma creatine kinase activity increased after NMES and peaked at D2 and D4, respectively. T2 was also increased at D2 (6%) and D4 (9%). Additionally, changes in MVC and peripheral factors (e.g., Db100) were correlated on the full recovery period, while a significant correlation was found between changes in MVC and VA only from D2 to D4. The decrease in MVC recorded immediately after the NMES session was mainly due to peripheral changes while both central and peripheral contributions were involved in the prolonged force reduction. Interestingly, the chronological events differ from what has been reported so far for voluntary exercise-induced muscle damage.
    Full-text · Article · Sep 2014 · PLoS ONE
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background The objective of this study was to quantify the transverse forces in skeletal muscle subjected to constant compressive massage-like loading (MLL) following eccentric exercise (ECC). Methods Twenty-eight New Zealand White rabbits were used for this two-part study. For all testing, a customized electromechanical device was utilized to apply a constant compressive force MLL to the tibialis anterior (TA) muscle and the resultant transverse forces were quantified. The device consisted of two stepper motors that were positioned orthogonally to each other and connected to separate sliding tracks. A stainless steel cylindrical massage tip was mounted to a customized two-axis sensor consisting of two strain gauges with which forces along the two axes were measured. First, we determined the effects of tissue loading frequency and compression magnitude on transverse forces in the TA. Following a bout of ECC, sixteen rabbits were randomly assigned to a protocol with MLL frequency of 0.25 Hz or 0.5 Hz at a constant compressive force of 5 N or 10 N. Secondly, we utilized a protocol of 0.5 Hz, 10 N, 15 min MLL that was performed on 4 consecutive days commencing immediately post ECC (n = 6 animals) or 48 hours following ECC (n = 6 animals). Transverse forces were measured during all 4 MLL sessions for the entire 15 min duration for both the immediate and the delayed groups. Results Both frequency and magnitude of compressive force due to MLL showed an effect on the magnitude of transverse force (p < 0.05 for each parameter). Furthermore, MLL beginning immediately following ECC produced higher transverse forces than MLL delayed by 48 hours with an average 20% difference between the two MLL groups over the four day protocol. Forces were higher in the middle 5 minutes compared to the first 5 minutes for all MLL bouts in both groups. Conclusions Frequency and magnitude of MLL and timing for delivery of MLL following ECC affect resultant transverse force values for exercised muscle. The application of our findings to humans receiving massage following exercise remains unknown at this time.
    Full-text · Article · Oct 2014 · BMC Complementary and Alternative Medicine
Show more