Activity Patterns of Human Skeletal Muscles: Relation to Muscle Fiber Type Composition

Monster, A. W.; Chan, Hing‐Yuen; O'Connor, D F

doi:10.1126/science.635587

Cited by 114 publications

(82 citation statements)

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“…In contrast, the longer bursts of the digastric, including all activities (>5%), would require more fatigue-resistant units, whereas the superficial masseter and medial pterygoid would require a mixture of fast and slow units, resulting from their bimodal distributions for activities exceeding the 5% level. High duty times imply prolonged muscle activity and this has been associated with large percentages of slow fatigueresistant fiber types (Monster et al, 1978;Kernell and Hensbergen, 1998). Although this might be true, the detailed characterization of muscle activity presented in the present study shows that high duty times can also be generated by large numbers of short bursts (see temporalis) and thus could be related to large percentages of fast fiber types.…”

Section: Discussionmentioning

confidence: 79%

“…Further analysis of video recordings could clarify the relationship between specific behavior and muscle activation exceeding different levels. The duty time has T. van Wessel and others 90% peak activity 50% peak activity 20% peak activity 5% peak activity Week 14 Week 9 Burst characteristics of jaw muscles previously been determined as a general indicator for daily muscle use (Monster et al, 1978;Hensbergen and Kernell, 1997;Langenbach et al, 2004;van Wessel et al, 2005). The present study also determined the daily burst number and length, providing a tool to examine the daily muscle use in more detail.…”

Section: Discussionmentioning

confidence: 90%

“…The total duration of muscle activity during the day, which is defined by the duty time (Hensbergen and Kernell, 1997;Langenbach et al, 2004), is associated with both the number of bursts and their lengths generated during the different motor tasks. Differences in duty time between muscles have been related to their fiber type composition (Monster, 1978;Kernell and Hensbergen, 1998). Muscles largely involved in postural activities generally show high duty times and contain a large percentage of slow type fibers.…”

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confidence: 99%

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Burst characteristics of daily jaw muscle activity in juvenile rabbits

Wessel

Langenbach

Kawai

et al. 2005

Journal of Experimental Biology

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Muscle activation varies with different behaviors and can be quantified by the level and duration of activity bursts. Jaw muscles undergo large anatomical changes during maturation, which are presumably associated with changes in daily muscle function. Our aim was to examine the daily burst number, burst length distribution and duty time (fraction of the day during which a muscle was active) of the jaw muscles of juvenile male rabbits (Oryctolagus cuniculus). A radio-telemetric device was implanted to record muscle activity continuously from the digastric, superficial and deep masseter, medial pterygoid and temporalis during maturation week 9-14. Daily burst characteristics and duty times were determined for activations, including both powerful and non-powerful motor behavior. All muscles showed constant burst numbers, mean burst lengths and duty times during the recording period. Including all behavior, the temporalis showed significantly larger daily burst numbers (205·000) and duty times (18.2%) than the superficial and deep masseter (90·000; 7.5%). Burst numbers and duty times were similar for the digastric (120·000; 11.1%) and medial pterygoid (115·000; 10.4%). The temporalis and deep masseter showed many short low activity bursts (0.05·s), the digastric showed many long bursts (0.09·s). For activations during powerful behaviors the superficial masseter and medial pterygoid had the largest burst numbers and duty times. Both muscles showed similar burst characteristics for all activation levels. It was concluded that activation of the jaw muscles is differently controlled during powerful and non-powerful motor behaviors and the functional organization of motor control patterns does not vary from 9 to 14 weeks of age.

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Section: Discussionmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 90%

mentioning

confidence: 99%

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Burst characteristics of daily jaw muscle activity in juvenile rabbits

Wessel

Langenbach

Kawai

et al. 2005

Journal of Experimental Biology

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“…The type I and type IIa MHC isoforms are abundantly expressed in muscles or muscle regions used for postural adjustment and for more endurance types of activity. In contrast, the types IIx and IIb isoforms are primarily concentrated in muscles or muscle regions used for short-duration and high-intensity power output activity (Monster et al, 1978;Green et al, 1984;Hoh, 1992;Schiaffino and Reggiani, 1996). The contractile properties of the m/m hybrid fibers depend on the relative amount of the different MHC contents.…”

Section: Physiological Properties Of Different Fiber Typesmentioning

confidence: 99%

Adult human mylohyoid muscle fibers express slow‐tonic, α‐cardiac, and developmental myosin heavy‐chain isoforms

Wang

et al. 2004

Anat. Rec.

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Some adult cranial muscles have been reported to contain unusual myosin heavy-chain (MHC) isoforms (i.e., slow-tonic, ␣-cardiac, embryonic, and neonatal), which exhibit distinct contractile properties. In this study, adult human mylohyoid (MH) muscles obtained from autopsies were investigated to detect the unusual MHC isoforms. For comparison, the biceps brachii and masseter muscles of the same subjects were also examined. Serial cross-sections from the muscles studied were incubated with a panel of isoform-specific anti-MHC monoclonal antibodies that distinguish major and unusual MHC isoforms. On average, the slow type I and fast type II MHC-containing fibers in the MH muscle accounted for 54% and 46% of the fibers, respectively. In contrast to limb and trunk muscles, the adult human MH muscle was characterized by a large proportion of hybrid fibers (85%) and a small percentage of pure fibers (15%; P Ͻ 0.01). Of the fast fiber types, the proportion of the type IIa MHC-containing fibers (92%) was much greater than that of the type IIx MHC-containing fibers (8%; P Ͻ 0.01). Our data demonstrated that the adult human MH fibers expressed the unusual MHC isoforms that were also identified in the masseter, but not in the biceps brachii. These isoforms were demonstrated by immunocytochemistry and confirmed by electrophoretic immunoblotting. Fiber-to-fiber comparisons showed that the unusual MHC isoforms were coexpressed with the major MHC isoforms (i.e., MHCI, IIa, and IIx), thus forming various major/unusual (or m/u) MHC hybrid fiber types. Interestingly, the unusual MHC isoforms were expressed in a fiber type-specific manner. The slow-tonic and ␣-cardiac MHC isoforms were coexpressed predominantly with slow type I MHC isoform, whereas the developmental MHC isoforms (i.e., embryonic and neonatal) coexisted primarily with fast type IIa MHC isoform. There were no MH fibers that expressed exclusively unusual MHC isoforms. Approximately 81% of the slow type I MHC-containing fibers expressed slow-tonic and ␣-cardiac MHC isoforms, whereas 80% of the fast type IIa MHC-containing fibers expressed neonatal MHC isoform. The m/u hybrid fibers (82% of the total fiber population) were found to constitute the predominant fiber types in the adult human MH muscle. At least seven m/u MHC hybrid fiber types were identified in the adult human MH muscle. The most common m/u hybrid fiber types were found to be the MHCI/slow-tonic/␣-cardiac and MHCIIa/neonatal, which accounted for 39% and 33% of the total fiber population, respectively. The multiplicity of MHC isoforms in the adult MH fibers is believed to be related to embryonic origin, innervation pattern, and unique functional requirements.

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“…Therefore, the types, proportions, and distribution patterns of the MHC-containing fibers in a given muscle are functionally designed. The muscles or muscle regions with a high proportion of fast type II fibers facilitate rapid and phasic movements, whereas those with a high proportion of type I fibers are generally involved in postural adjustments (Monster et al, 1978;Hoh, 1992;Schiaffino and Reggiani, 1996). In this regard, the CTP (type I 62%) is relatively slower than the CT-o (type I 53%).…”

Section: Possible Functional Implicationsmentioning

confidence: 96%

Newly Revealed Cricothyropharyngeus Muscle in the Human Laryngopharynx

Sanders

2008

The Anatomical Record

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Humans have a uniquely curved pharynx and tongue that is believed to have evolved for speech. The most inferior part of the pharynx consists of the laryngopharynx, the critical crossroad where swallowing, breathing, and phonation overlap. We hypothesized that the human laryngopharynx has unique neuromuscular specializations that may be speech related. Laryngopharynx specimens from 15 humans and 20 nonhuman mammals (dog, pig, rabbit, and rat) were studied. Microdissection revealed that only human specimens had a muscle originating from the anterior arch of the cricoid cartilage, and coursing between the inferior pharyngeal constrictor and cricopharyngeus muscles to insert into the median raphe at the posterior midline of the pharynx. On the basis of these anatomic features, we termed it the ''cricothyropharyngeus'' (CTP). The structure, innervation, and muscle fiber types of the human CTP were further investigated by histological methods, Sihler's stain, and myosin heavy chain (MHC) immunocytochemistry. The innervation and muscle fiber types of the CTP were found to differ from those of neighboring muscles. The laryngeal portion of the CTP was innervated by the external superior laryngeal nerve, whereas the pharyngeal portion of the muscle was supplied by the pharyngeal plexus. Most notable was that the CTP contained specialized muscle fibers expressing some unusual MHC isoforms (i.e., slow-tonic, a-cardiac, neonatal, and embryonic). In conclusion, the CTP appears to be a newly described and uniquely human muscle with characteristics suggesting a specialized function that may be speech related. Anat Rec, 291:927-938, 2008. 2008 Wiley-Liss, Inc.Key words: cricothyropharyngeus; laryngopharynx; innervation; MHC isoforms; fiber types; Sihler's stain; immunocytochemistry Laryngopharynx, the most inferior part of the pharynx, lies below the oropharynx and posterior to the larynx. It extends from the epiglottis superiorly down to the inferior border of the cricoid at C6. Laryngopharyngeal region is involved in important life-maintaining functions such as swallowing, respiration, and phonation. The muscles in this region have several special features. These features include that they are relatively small in size, organized into compartments, attached to the laryngeal cartilages (cricoid and thyroid cartilages), and innervated by different nerves (superior laryngeal nerve, recurrent laryngeal nerve, and

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Activity Patterns of Human Skeletal Muscles: Relation to Muscle Fiber Type Composition

Cited by 114 publications

References 29 publications

Burst characteristics of daily jaw muscle activity in juvenile rabbits

Burst characteristics of daily jaw muscle activity in juvenile rabbits

Adult human mylohyoid muscle fibers express slow‐tonic, α‐cardiac, and developmental myosin heavy‐chain isoforms

Newly Revealed Cricothyropharyngeus Muscle in the Human Laryngopharynx

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