Radiographically determined widths of bone muscle and fat in the upper arm and calf from age 3–18 years

Tanner, J. M.; Hughes, P. C. R.; Whitehouse, R. H.

doi:10.1080/03014468100005351

Cited by 124 publications

(74 citation statements)

References 37 publications

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“…These results are in agreement with the extant literature, which suggests that although on average, boys may have slightly larger muscles and perform slightly better in muscle function tests than girls in early childhood, these differences are generally not signifi cant (17,23). Similarly, there were no signifi cant gender differences in brachialis moment arm lengths or mechanical advantage across the range of motion examined.…”

Section: Discussionsupporting

confidence: 82%

Elbow Flexor Strength, Muscle Size, and Moment Arms in Prepubertal Boys and Girls

Wood¹,

Dixon²,

Grant³

et al. 2006

Pediatric Exercise Science

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The aim of this study was to examine elbow fl exion torque, muscle cross-sectional area (CSA), and leverage in boys and girls. Thirty-eight prepubertal children (9.6 ± 0.3 years) volunteered to participate. All performed isometric fl exion actions at 10°, 50°, and 90° of elbow fl exion. Magnetic resonance imaging was used to assess elbow fl exor (EF) muscle CSA and brachialis moment arm lengths. No signifi cant gender differences were observed for any of the variables studied. EF CSA was directly proportional to isometric torque at 50° and 90°. CSA explained between 47% and 57% of torque variance. Moment arm estimates explained 19% of the variance in isometric torque at 90°. These baseline data contribute to our understanding of factors infl uencing strength variation during childhood.Upper-extremity strength differences between boys and girls are of particular interest, given that by adulthood, males outperform females in practically all upper-body sport events involving a strength component (10). Examination of the factors contributing to strength variation will aid our understanding of differences in upper-body performance, but initial baseline data on prepubertal children are required in order to put observations during growth and maturation into context.The majority of studies have focused on the ability of intrinsic muscle properties to explain strength variation (4); relatively few have examined extrinsic factors, which include the role of anatomy and biomechanics (5). However, unless muscle force is measured directly at the tendon or at the point of application of a load, leverage (an extrinsic factor) will infl uence measurements of strength. When strength is expressed as joint torque, it represents the product of all the muscle forces and their moment arms contributing to a specifi ed joint action. Given that muscle force is also infl uenced by moment arm length via its effect on musculotendinous length changes and velocity, it is important to understand the role of variation in moment arm lengths, across a joint range of motion and between individuals, in torque development (15).

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Section: Discussionsupporting

confidence: 82%

Elbow Flexor Strength, Muscle Size, and Moment Arms in Prepubertal Boys and Girls

Wood¹,

Dixon²,

Grant³

et al. 2006

Pediatric Exercise Science

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“…Sex differences in muscularity become apparent from 13 years of age, with a larger relative difference in the upper than in the lower body (Tanner et al, 1981;Kanehisa et al, 1994). For adolescent boys and girls, however, relatively little information on the extent of sex differences in the muscularity of the trunk is available.…”

Section: Introductionmentioning

confidence: 99%

Sex Differences in the Cross-sectional Areas of Psoas Major and Thigh Muscles in High School Track and Field Athletes and Nonathletes

Hoshikawa

Muramatsu

Iida

et al. 2011

J Physiol Anthropol

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The present study aimed to examine the sex differences in the cross-sectional areas of the psoas major, quadriceps femoris, hamstrings, and adductors in high school track and field athletes and nonathletes. The cross-sectional areas of the psoas major at L4-L5 and three thigh muscles at the mid-thigh were determined in the right side of the body using magnetic resonance imaging in 61 sprinters (29 boys and 32 girls), 50 jumpers (28 boys and 22 girls), 33 throwers (18 boys and 15 girls), and 40 nonathletes (20 boys and 20 girls), aged from 16 to 18 yrs. On the whole, the cross-sectional area for every muscle group was greater in the athletes than in the nonathletes and in the boys than in the girls. The average value of the cross-sectional area for the girls as a percentage of that for the boys in every subject group was lower in the psoas major (57.6-64.7%) than in the thigh muscles (67.8-82.9%). Among the thigh muscles, the muscle group which showed significant sex differences in the ratio of cross-sectional area to the two-third power of lean body mass was limited to the quadriceps femoris in the sprinters and nonathletes and hamstrings in the throwers. However, the ratio for the psoas major was significantly higher in the boys than in the girls in all subject groups. The current results indicate that, although regular participation in sports training during adolescence promotes hypertrophy in the psoas major and thigh muscles in not only boys but also girls, a greater sex difference exists in the muscularity of the psoas major than of the thigh muscles, in athletes and nonathletes.

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“…For example, during male puberty the estimated peak periosteal apposition rate of the metacarpal is ϳ0.5 m/day, but it is close to 2 m/day at the midshaft humerus. 21 What is less widely appreciated is that periosteal growth is not necessarily synchronized between bones. For example, in 3-month-old infants, the humerus grows in width one-third faster than the femur 8 (Fig 3).…”

Section: Bone Accrual On Periosteal Surfacesmentioning

confidence: 99%

Bone Accrual in Children: Adding Substance to Surfaces

Rauch

2007

Pediatrics

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The mass of growing bones increases through changes in outer dimensions and through the net addition of tissue on inner bone surfaces. In this overview I examine bone accrual as it occurs on trabecular (inner) and periosteal (outer) surfaces. In the axial skeleton, the amount of trabecular bone increases during development, because trabeculae grow thicker as a result of bone remodeling with a positive balance. Remodeling is a process in which osteoblasts and osteoclasts are tightly linked ("coupled") in time and space. In contrast to trabecular thickness, trabecular number and material density change little throughout development. Bone accrual on periosteal surfaces leads to an increase in bone size, which is a crucial determinant of bone strength throughout life. Periosteal osteoblasts deposit new bone on an extended surface area and over an extended period of time without being interrupted by osteoclasts. This type of bone metabolic activity is called modeling, which is much more efficient than remodeling for increasing bone mass. In the past, research has focused on bone remodeling on trabecular surfaces. However, the key to an improved understanding of bone mass and strength development in children will lie with studies on bone modeling on periosteal surfaces.www.pediatrics.org/cgi

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Radiographically determined widths of bone muscle and fat in the upper arm and calf from age 3–18 years

Cited by 124 publications

References 37 publications

Elbow Flexor Strength, Muscle Size, and Moment Arms in Prepubertal Boys and Girls

Elbow Flexor Strength, Muscle Size, and Moment Arms in Prepubertal Boys and Girls

Sex Differences in the Cross-sectional Areas of Psoas Major and Thigh Muscles in High School Track and Field Athletes and Nonathletes

Bone Accrual in Children: Adding Substance to Surfaces

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