Effect of Maturation on the Relationship between Muscle Size and Force Production

Tonson, Anne; Ratel, Sébastien; Fur, Yann Le; Cozzone, P. J.; Bendahan, David

doi:10.1249/mss.0b013e3181641bed

Cited by 98 publications

(109 citation statements)

References 38 publications

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“…These contradictory findings might be related to methodological aspects because specific force has been measured differently in the corresponding studies, e.g., with CSA, isolated muscle weight, fiber length, or muscle density (4,6,26) chosen as surrogate markers of muscle volume. By contrast, we quantified muscle volume from multiple MR images, and this technique is considered a gold standard in this field (11,31). Muscle performance impairment reported herein and in previous studies in Mstn-deficient animals warrants further clarification.…”

Section: Nsmentioning

confidence: 90%

“…The setup integrates an ergometer consisting of a foot pedal coupled to a force transducer and two rod-shaped transcutaneous surface electrodes (one located above the knee and the other under the heel) connected to an electrical stimulator (Type 215/T; Hugo Sachs Elektronik-Harvard Apparatus, March-Hugstetten, Germany). The foot was positioned on the ergometer pedal, and the lower hindlimb was centered inside a 20-mmdiameter 1 H Helmholtz imaging coil while the belly of the gastrocnemius muscle was located above an elliptic (8 ϫ 12 mm) 31 P-MRS surface coil. The pedal position was adjusted to modify the angle between the foot and the lower hindlimb so that the gastrocnemius muscle could be passively stretched at rest to produce a maximum isometric twitch tension in response to supramaximal square wave pulses (1.5-ms duration; 2-4 mA).…”

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confidence: 99%

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Lack of myostatin impairs mechanical performance and ATP cost of contraction in exercising mouse gastrocnemius muscle in vivo

Giannesini

Vilmen

Amthor

et al. 2013

American Journal of Physiology-Endocrinology and Metabolism

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Although it is well established that the lack of myostatin (Mstn) promotes skeletal muscle hypertrophy, the corresponding changes regarding force generation have been studied mainly in vitro and remain conflicting. Furthermore, the metabolic underpinnings of these changes are very poorly documented. To clarify this issue, we have investigated strictly noninvasively in vivo the impact of the lack of Mstn on gastrocnemius muscle function and energetics in Mstn-targeted knockout (Mstn Ϫ/Ϫ ) mice using 1 H-magnetic resonance (MR) imaging and 31 P-MR spectroscopy during maximal repeated isometric contractions induced by transcutaneous electrostimulation. In Mstn Ϫ/Ϫ animals, although body weight, gastrocnemius muscle volume, and absolute force were larger (ϩ38, ϩ118, and ϩ34%, respectively) compared with wild-type (Mstn ϩ/ϩ ) mice, specific force (calculated from MR imaging measurements) was significantly lower (Ϫ36%), and resistance to fatigue was decreased. Besides, Mstn deficiency did not affect phosphorylated compound concentrations and intracellular pH at rest but caused a large increase in ATP cost of contraction (up to ϩ206% compared with Mstn ϩ/ϩ ) throughout the stimulation period. Further, Mstn deficiency limits the shift toward oxidative metabolism during muscle activity despite the fact that oxidative ATP synthesis capacity was not altered. Our data demonstrate in vivo that the absence of Mstn impairs both mechanical performance and energy cost of contraction in hypertrophic muscle. These findings must be kept in mind when considering Mstn as a potential therapeutic target for increasing muscle mass in patients suffering from muscle-wasting disorders. adenosine 5=-triphosphate; skeletal muscle; hypertrophy; energy metabolism; fatigue; nuclear magnetic resonance MYOSTATIN (Mstn) is part of the transforming growth factor-␤ signaling molecule family and acts as an endogenous negative regulator of skeletal muscle growth in mammalians (23). The absence or postnatal blockade of Mstn results in a large and widespread increase in skeletal muscle mass (20,23,24).

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Section: Nsmentioning

confidence: 90%

mentioning

confidence: 99%

Lack of myostatin impairs mechanical performance and ATP cost of contraction in exercising mouse gastrocnemius muscle in vivo

Giannesini

Vilmen

Amthor

et al. 2013

American Journal of Physiology-Endocrinology and Metabolism

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“…Utilizing differing analytical approaches the reported results with respect to CSA-normalized peak torque are inconsistent (8,25,30,37,47). A few female studies reported the absence of age-related differences in CSA-normalized peak torque (8,31).…”

Section: Discussionmentioning

confidence: 99%

Muscle Strength and Contractile Kinetics of Isometric Elbow Flexion in Girls and Women

Falk

Brunton²,

Dotan³

et al. 2009

Pediatric Exercise Science

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Ten prepubertal girls and 15 young women were tested for maximal torque, peak rate of torque development, electro-mechanical delay (EMD), and time to peak rate of torque development during isometric elbow flexion. Absolute peak torque (17.0 ± 7.7 vs. 40.5 ± 8.3 Nm) and peak rate of torque development (105.9 ± 58.6 vs. 297.2 ± 113.0 Nm·s −1 ) were lower in the girls (p < .05). Normalized to muscle cross sectional area, torque was similar (8.27 ± 2.74 vs. 8.44 ± 1.65 Nm·cm −2 ), as was peak rate of torque development, normalized to peak torque (6.21 ± 1.94 vs. 7.30 ± 2.26 Nm·s −1 /Nm). Both, time to peak rate of torque development (123.8 ± 36.0 vs. 110.5 ± 52.6 ms) and EMD (73.2 ± 28.6 vs. 51.9 ± 25.6 ms), were longer in the girls, although EMD's difference only approached statistical significance (p = .06). Age-related isometric strength differences in females appear to be mainly muscle-size dependent. However, the time to peak torque and EMD findings suggest differential motor-unit activation which may functionally manifest itself in fast dynamic contractions.Numerous studies have demonstrated that children's maximal muscle strength is lower than that of adults (5,18,42). In males, muscle strength is consistently lower in boys even when normalized for body size (5,42 CIHR Author ManuscriptCIHR Author Manuscript CIHR Author Manuscript some studies report a lower body size-normalized strength in girls compared with women (29), others do not (5,28,31,38,43).Several factors, besides body size may contribute to age-related differences in maximal strength, including differences in muscle activation, fiber composition, and agonistantagonist cocontraction. The scant available literature on muscle fiber composition suggests that the latter is similar in children and adults (12). This is supported by the similar contractile characteristics (contraction time and half-relaxation time) during electrically evoked twitch contraction in children and adults (4,8,9,22,35,39). Although few studies have suggested a lower percentage of type II muscle fibers in boys compared with men (15,34), the difference is too small to account for the age-related muscle strength differences observed between boys and men. No comparison of muscle fiber-type composition has been reported between girls and women.The rate or degree of muscle activation has been suggested to be lower in boys compared with men, based on indirect evidence and varying techniques (1,2,4,5,23,25,33,39,45). However, all these comparisons were made with heterogeneous or male-only samples. There are no comparisons of muscle activation indices or examination of their roles in girl-woman strength differences.Differences in the rate of force development are likely manifestations of the nature of muscle activation or its composition. It too appears to be lower in children than in adults, whether measured during maximal voluntary (1,21), or electrically stimulated twitch contractions (4,22), but has been demonstrated only in males. No age comparisons have been published fo...

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“…While most investigators have found that whole muscle force is proportional to size, it is recognized that the method used to determine muscle size, and possibly age, influence the strength-size relationship (Tonson et al 2008). A mathematical approach somewhat similar to the one we have used has been applied to the relationship between biceps whole muscle size and strength.…”

Section: S Krivickas and Othersmentioning

confidence: 99%

Relationship between force and size in human single muscle fibres

Krivickas

Dorer

Ochala

et al. 2011

Experimental Physiology

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When the contractile properties of single muscle fibres are studied, force is typically normalized by fibre cross-sectional area and expressed as specific force. We studied a set of 2725 chemically skinned human single muscle fibres from 119 healthy adults to determine whether specific force is the optimal way to express the relationship between single-fibre force and size. A linear mixed effects model was used to estimate the slope and slope variability among individuals of log-log plots of force and diameter. For type I fibres, the slope estimate was 0.99 (95% confidence interval 0.36-1.62), and for type IIa fibres it was 0.94 (95% confidence interval 0.77-1.11), indicating that force is proportional to fibre diameter, rather than to cross-sectional area. If force were proportional to cross-sectional area, the slope estimate would be 2.0. In future studies using the chemically skinned single fibre preparation, force may be normalized to fibre diameter rather than cross-sectional area. We propose that a new term, 'normalized force', be used for this variable, with units of newtons per metre. We demonstrate using our data set that when populations of single fibres are compared with one another, the determination of whether the size and force relationship is the same or different is dependent upon the method used to account for fibre size (i.e. specific force versus 'normalized force').

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Effect of Maturation on the Relationship between Muscle Size and Force Production

Cited by 98 publications

References 38 publications

Lack of myostatin impairs mechanical performance and ATP cost of contraction in exercising mouse gastrocnemius muscle in vivo

Lack of myostatin impairs mechanical performance and ATP cost of contraction in exercising mouse gastrocnemius muscle in vivo

Muscle Strength and Contractile Kinetics of Isometric Elbow Flexion in Girls and Women

Relationship between force and size in human single muscle fibres

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