The impact of biochemical methods for single muscle fibre analysis

Abstract

The neural and muscular changes during fatigue produced in repeated submaximal static contractions of knee extensors were measured. Three groups of differently adapted male subjects (power-trained, endurance-trained and untrained, 15 in each) performed the exercise that consisted of 10 trials of submaximal static contractions at the level of 40% of maximal voluntary contraction (MVC) force till exhaustion with the inter-trial rest intervals of 1 min. MVC force, reaction time and patellar reflex time components before and after the fatiguing exercise and following 5, 10 and 15 min of recovery were recorded. Endurance-trained athletes had a significantly longer holding times for all the 10 trials compared with power-trained athletes and untrained subjects. However, no significant differences in static endurance between power-trained athletes and untrained subjects were noted. The fatigue test significantly prolonged the time between onset of electrical and mechanical activity (electromechanical delay) in voluntary and reflex contractions. The electromechanical delay in voluntary contraction condition for power-trained and untrained subjects and in reflex condition for endurance-trained subjects had not recovered 15 min after cessation of exercise. No significant changes in the central component of visual reaction time (premotor time of MVC) and latency of patellar reflex were noted after fatiguing static exercise. It is concluded, that in this type of exercise the fatigue development may be largely owing to muscle contractile failure.

Characterisation of human soft palate muscles with respect to fibre types, myosins and capillary supply

“…The MyHC isoform composition of the different palate and control muscle fibres was in general closely correlated with their enzyme-histochemical profile and in agreement with previous observations on MyHC composition in human limb (for reviews see Staron, 1997 ;Pette et al 1999) and facial muscles (Sta/ l et al 1994). Type I fibres contained exclusively slow MyHC and type IIC and IM fibres various proportions of slow MyHC and fast A MyHC.…”

“…Slow MyHC is present in type I fibres and is coexpressed with fast MyHC in type IIC fibres. Fast A MyHC is mainly present in type IIA fibres and fast X MyHC, and not fast B MyHC, is expressed in type IIB fibres (for reviews see Staron, 1997 ;Pette et al 1999). Whether a fast B MyHC is expressed in human muscles is still unclear (Weiss et al 1999).…”

“…As several MyHC isoforms can be coexpressed in single muscle fibres (e.g. Staron, 1997 ;Pette et al 1999), especially in human cranial muscles (Sciote et al 1994 ;Sta/ l et al 1994 ;Monemi et al 1999), a fibre classification based on the MyHC composition would be rather intricate. For comparison the study included 1 human arm, 1 hand and 1 facial muscle from each subject.…”

Distribution Pattern of Muscle Fiber Types in the Perivertebral Musculature of Two Different Sized Species of Mice

“…Type IIX fibers are histochemically very similar to Type IIB fibers and MHC IIx has been shown to be expressed in fibers histochemically identified as Type IIB, but both types differ in their contractile properties (Pette et al, 1999;Smerdu et al, 2009). In contrast to small mammals, results on larger species have shown that only MHC IIa and IIx were expressed but not MHC IIb (e.g., cat: Talmadge et al, 1996;dog: Snow et al, 1982;Š trbenc et al, 2004;goat: Argü ello et al, 2001;sheep: Maier et al, 1992;human: Smerdu et al, 1994;Ennion et al, 1995;horse: Rivero et al, 1996;Eizema et al, 2003;cattle: Tanabe et al, 1998;brown bear: Smerdu et al, 2009).…”

“…Type IIX fibers were shown to range between IIA and IIB fibers in their contractile properties, such as maximum shortening velocity, myosin ATPase activity, or phosphocreatine levels (for review see Pette et al, 1999), but whether their properties resembled more IIA or IIB fibers depended on the species and muscles studied as well as the specific experimental conditions. In the current study, only three fiber types were distinguished out of the continuum of so far identified muscle fiber (sub)types.…”