Abstract
Aim: The aim of this paper was to determine whether; (1) patella tendon stiffness, (2) the magnitude of vastus lateralis fascicle lengthening, and (3) eccentric torque correlate with markers of exercise induced muscle damage.Method: Combining dynamometry and ultrasonography, patella tendon properties and vastus lateralis architectural properties were measured pre and during the first of six sets of 12 maximal voluntary eccentric knee extensions. Maximal isometric torque loss and creatine kinase activity were measured pre-damage (−48 h), 48, 96, and 168 h post-damage as markers of exercise-induced muscle damage.Results: A significant increase in creatine kinase (883 ± 667 UL) and a significant reduction in maximal isometric torque loss (21%) was reported post-eccentric contractions. Change in creatine kinase from pre to peak significantly correlated with the relative change in vastus lateralis fascicle length during eccentric contractions (r = 0.53, p = 0.02) and with eccentric torque (r = 0.50, p = 0.02). Additionally, creatine kinase tended to correlate with estimated patella tendon lengthening during eccentric contractions (p < 0.10). However, creatine kinase did not correlate with resting measures of patella tendon properties or vastus lateralis properties. Similarly, torque loss did not correlate with any patella tendon or vastus lateralis properties at rest or during eccentric contractions.Conclusion: The current study demonstrates that the extent of fascicle strain during eccentric contractions correlates with the magnitude of the creatine kinase response. Although at rest, there is no relationship between patella tendon properties and markers of muscle damage; during eccentric contractions however, the patella tendon may play a role in the creatine kinase response following EIMD.
Highlights
It is well accepted that unaccustomed eccentric exercise results in functional and cytoskeletal impairments, referred to as exercise-induced muscle damage (EIMD), the mechanical determinants, which govern the severity of EIMD still remains unclear
The current study reports three main findings; (1) During EIMD, Vastus lateralis (VL) relative fascicle lengthening, Maximal voluntary eccentric knee extensions (MVEKE) torque and negative work correlated significantly with CKpeak, (2) Patella tendon properties did not correlate with CKpeak or Maximal voluntary isometric knee extension (MVCKE) torque loss
Despite the tendon gaining a reputation as a “mechanical buffer” during EIMD, in agreement with our previous work (Hicks et al, 2013), the current study reported no significant correlation between patella tendon stiffness and CKpeak
Summary
It is well accepted that unaccustomed eccentric exercise results in functional and cytoskeletal impairments, referred to as exercise-induced muscle damage (EIMD), the mechanical determinants, which govern the severity of EIMD still remains unclear. The differences in EIMD have been attributed to fascicle strain (Lieber and Friden, 1993; Peñailillo et al, 2015; Guilhem et al, 2016), eccentric force (Warren et al, 1993; Chapman et al, 2008), the elastic properties of the tendon ( not confirmed experimentally) (Marginson et al, 2005; Guilhem et al, 2016) and, in women, circulating estrogen levels (Carter et al, 2001) At present, these aforementioned determinants have predominately been identified using various in situ and in vitro conditions, with limited studies investigating the determinants in vivo (Chapman et al, 2008; Peñailillo et al, 2013; Hoffman et al, 2014; Guilhem et al, 2016). To investigate whether tendon stiffness correlates with markers of EIMD, a range of tendon stiffness’s need to be investigated whilst controlling for confounding variables such as sex
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