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- Li, Xiao, et al.
(författare)
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The A55T and K153R polymorphisms of MSTN gene are associated with the strength training-induced muscle hypertrophy among Han Chinese men.
- 2014
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Ingår i: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 32:9, s. 883-91
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Tidskriftsartikel (refereegranskat)abstract
- Myostatin, encoded by the MSTN gene, is a strong regulator of skeletal muscle growth. The present study aimed to investigate whether the A55T and K153R polymorphisms of MSTN were associated with the strength training-induced muscle hypertrophy among Han Chinese men. A total of 94 healthy, untrained men were recruited for an 8-week strength training programme. The thicknesses of biceps and quadriceps, along with anthropometric measurements of the participants, were assessed before and after the programme. The MSTN polymorphisms were subsequently genotyped employing polymerase chain reaction-restriction fragment length polymorphism technique and confirmed by DNA sequencing. One-way analysis of variance was used to compare the pre- and post-training measurements between carriers of different polymorphic genotypes. Our results indicated that individuals with AT + TT genotype of the A55T polymorphism showed a significant increase in the thickness of biceps (0.292 ± 0.210 cm, P = 0.03), but not quadriceps (0.254 ± 0.198 cm, P = 0.07), compared to carriers of AA genotype. For the K153R polymorphism, the increases in the thicknesses of both biceps (0.300 ± 0.131 cm) and quadriceps (0.421 ± 0.281 cm) were significantly higher among individuals with KR than those with KK genotypes (P < 0.01 for both muscles). The results obtained therefore suggested a possible association between the two polymorphisms and the strength training-induced muscle hypertrophy among men of Han Chinese ethnicity.
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| 2. |
- Wang, Ruoli, et al.
(författare)
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Passive Mechanical Properties of Human Medial Gastrocnemius and Soleus Musculotendinous Unit.
- 2021
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Ingår i: BioMed Research International. - : Hindawi Publishing Corporation. - 2314-6133 .- 2314-6141. ; 2021
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Tidskriftsartikel (refereegranskat)abstract
- The in vivo characterization of the passive mechanical properties of the human triceps surae musculotendinous unit is important for gaining a deeper understanding of the interactive responses of the tendon and muscle tissues to loading during passive stretching. This study sought to quantify a comprehensive set of passive muscle-tendon properties such as slack length, stiffness, and the stress-strain relationship using a combination of ultrasound imaging and a three-dimensional motion capture system in healthy adults. By measuring tendon length, the cross-section areas of the Achilles tendon subcompartments (i.e., medial gastrocnemius and soleus aspects), and the ankle torque simultaneously, the mechanical properties of each individual compartment can be specifically identified. We found that the medial gastrocnemius (GM) and soleus (SOL) aspects of the Achilles tendon have similar mechanical properties in terms of slack angle (GM: -10.96° ± 3.48°; SOL: -8.50° ± 4.03°), moment arm at 0° of ankle angle (GM: 30.35 ± 6.42 mm; SOL: 31.39 ± 6.42 mm), and stiffness (GM: 23.18 ± 13.46 Nmm-1; SOL: 31.57 ± 13.26 Nmm-1). However, maximal tendon stress in the GM was significantly less than that in SOL (GM: 2.96 ± 1.50 MPa; SOL: 4.90 ± 1.88 MPa, p = 0.024), largely due to the higher passive force observed in the soleus compartment (GM: 99.89 ± 39.50 N; SOL: 174.59 ± 79.54 N, p = 0.020). Moreover, the tendon contributed to more than half of the total muscle-tendon unit lengthening during the passive stretch. This unequal passive stress between the medial gastrocnemius and the soleus tendon might contribute to the asymmetrical loading and deformation of the Achilles tendon during motion reported in the literature. Such information is relevant to understanding the Achilles tendon function and loading profile in pathological populations in the future.
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