Influence of body adiposity on structural characteristics of skeletal muscle in men and women

New Findings r What is the central question of this study?Do obesity-specific factors affect skeletal muscle performance in older individuals? r What is the main finding and its importance?Older obese women have a larger quadriceps femoris size but develop lower tension per unit of skeletal muscle than their normal-weight counterparts.Muscle impairment and excess body mass are very common among older people. Given that the effect of obesity on strength production has scarcely been studied in older individuals, we analysed functional and structural characteristics of quadriceps femoris (QF) in obese (OB) and normal-weight (NW) older women with comparable habitual physical activity. In five OB (body mass index 36.8 ± 1.9 kg m −2 , age 72.4 ± 2.3 years) and six NW well-functioning older women (body mass index 24.3 ± 1.8 kg m −2 , age 72.7 ± 1.9 years), peak knee-extension torque (KET) was measured in isometric (90 deg knee flexion) and isokinetic conditions (240, 180, 120 and 60 deg s −1 ). Mid-thigh QF cross-sectional area (CSA) and muscle tissue fat content (MF%) were determined with magnetic resonance imaging (Dixon sequence). Muscle fascicle length and pennation angle (PA) were assessed with ultrasonography for each muscle belly of the QF (vastus lateralis, vastus intermedius, rectus femoris and vastus intermedius). Despite similar values of KET, CSA was 17.0% larger in OB than in NW women (P < 0.05), so that KET/CSA was significantly lower (P < 0.05) in OB women. Compared with NW women, OB women had 28.7% higher MF% (P < 0.05) and 24.9% higher average PA (P < 0.05), while fascicle length was similar. Overall, isometric KET/CSA was negatively affected by both MF% (P < 0.05) and PA (P < 0.05), while isokinetic KET/CSA was negatively affected only by MF% (P < 0.01). Muscle composition and architecture seem to be important determinants of KET/CSA in elderly women. In fact, owing to the effect of obesity overload, OB women have a larger QF size than NW women, but unfavourable muscle composition and architecture. The higher MF% and steeper PA observed in OB women are associated with reduced levels of muscle specific strength.

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“…; Lafortuna et al . ). The basis on which to build this hypothesis had been provided by Goodpaster et al .…”

Section: Discussionmentioning

confidence: 97%

“…; Lafortuna et al . , ). The augmented muscle mass shown by obese individuals is considered to be the result of the load imposed by the larger body mass acting as a chronic stimulus to muscle tissue.…”

Section: Discussionmentioning

confidence: 99%

Effects of muscle composition and architecture on specific strength in obese older women

Rastelli

Capodaglio

Orgiu

et al. 2015

Experimental Physiology

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“…Obesity in both young and old individuals has been shown to induce a loading effect on skeletal muscles of the lower limbs (Lafortuna et al. ), increasing absolute maximal voluntary contraction (MVC) torque in obese compared with both normal and underweight individuals (Rolland et al. ; Maffiuletti et al.…”

Section: Introductionmentioning

confidence: 99%

The impact of obesity on skeletal muscle architecture in untrained young vs. old women

et al. 2014

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It is unknown whether loading of the lower limbs through additional storage of fat mass as evident in obesity would promote muscular adaptations similar to those seen with resistance exercise. It is also unclear whether ageing modulates any such adjustments. This study aimed to examine the relationships between adiposity, ageing and skeletal muscle size and architecture. A total of 100 untrained healthy women were categorised by age into young (Y) (mean AE SD: 26.7 AE 9.4 years) vs. old (O) (65.1 AE 7.2 years) and body mass index (BMI) classification (underweight, normal weight, overweight and obese). Participants were assessed for body fat using dual energy x-ray absorptiometry, and for gastrocnemius medialis (GM) muscle architecture (skeletal muscle fascicle pennation angle and length) and size [GM muscle volume and physiological cross-sectional area (PCSA)] using B-mode ultrasonography. GM fascicle pennation angle (FPA) in the obese Y females was 25% greater than underweight (P = 0.001) and 25% greater than normal weight (P = 0.001) individuals, while O females had 32 and 22% greater FPA than their underweight (P = 0.008) and normal weight (P = 0.003) counterparts. Furthermore, FPA correlated with body mass in both Y and O females (Y r = 0.303; P < 0.001; O r = 0.223; P = 0.001), yet no age-related differences in the slope or r-values were observed (P > 0.05). Both GM muscle volume (P = 0.003) and PCSA (P = 0.004) exhibited significant age 9 BMI interactions. In addition, muscle volume and PCSA correlated with BMI, body mass and fat mass. Interestingly, ageing reduced both the degree of association in these correlations (P < 0.05) and the slope of the regressions (P < 0.05). Our findings partly support our hypotheses in that obesity-associated changes in GM PCSA and volume differed between the young and old. The younger GM muscle adapted to the loading induced by high levels of body mass, adiposity and BMI by increasing its volume and increasing its pennation angle, ultimately enabling it to produce higher maximum torque. Such an adaptation to increased loading did not occur in the older GM muscle. Nonetheless, the older GM muscle FPA increased to a similar extent to that seen in young GM muscle, an effect which partly explains the relatively enhanced absolute maximum torque observed in obese older females.

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“…Indeed, most of the study participants with DS were overweight or obese. Obese or overweight persons are generally stronger than normal or underweight individuals; this is most likely due to the fact that obesity causes a loading effect on muscles, namely, antigravity muscles [23]. Recent studies show that obesity or overweight have a different effect on muscle architecture according to age.…”

Section: Discussionmentioning

confidence: 99%

Relationships between Muscle Architecture of Rectus Femoris and Functional Parameters of Knee Motion in Adults with Down Syndrome

Valle

Casabona

Micale

et al. 2016

BioMed Research International

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This study was designed to measure in vivo muscle architecture of the rectus femoris in adults with Down syndrome, testing possible relationships with functional parameters of the knee motion. Ten adults with Down syndrome and ten typically developed participated in the study. Pennation angle and thickness of the rectus femoris and subcutaneous layer of the thigh were measured via ultrasound imaging. Knee kinematics and electromyographic activity of the rectus femoris were recorded during free leg dropping. Muscle thickness was reduced and subcutaneous layer was thicker in persons with Down syndrome with respect to typically developed adults, but there were no differences in the pennation angle. The area of the rectus femoris EMG activity during the leg flexion was greater in Down syndrome with respect to typically developed adults. The leg movement velocity was lower in Down people than in controls, but the knee excursion was similar between the groups. Functional parameters correlated with pennation angle in the persons with Down syndrome and with muscle thickness in typically developed persons. The description of muscle architecture and the relationships between morphological and functional parameters may provide insights on the limits and the opportunities to overcome the inherent biomechanical instability in Down syndrome.

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Influence of body adiposity on structural characteristics of skeletal muscle in men and women

Cited by 30 publications

References 38 publications

Effects of muscle composition and architecture on specific strength in obese older women

Effects of muscle composition and architecture on specific strength in obese older women

The impact of obesity on skeletal muscle architecture in untrained young vs. old women

Relationships between Muscle Architecture of Rectus Femoris and Functional Parameters of Knee Motion in Adults with Down Syndrome

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