Possibility for Visualizing the Muscle Microstructure by q-Space Imaging Technique.

In the human body, skeletal muscle microstructures have been evaluated only by biopsy. Noninvasive examination of the microstructure of muscles would be useful for research and clinical practice in sports and musculoskeletal areas. The study is aimed at determining if q-space imaging (QSI) can reveal the microstructure of muscles in humans. Forty-three Japanese subjects (controls, distance runners, powerlifting athletes, and teenage runners) were included in this cross-sectional study. Magnetic resonance imaging of the lower leg was performed. On each leg muscle, full width at half maximum (FWHM) which indicated the muscle cell diameters and pennation angle (PA) were measured and compared. FWHM showed significant positive correlations with PA, which is related to muscle strength. In addition, FWHM was higher for powerlifting, control, distance running, and teenager, in that order, suggesting that it may be directing the diameter of each muscle cell. Type 1 and type 2 fibers are enlarged by growth, so the fact that the FWHM of the control group was larger than that of the teenagers in this study may indicate that the muscle fibers were enlarged by growth. Also, FWHM has the possibility to increase with increased muscle fibers caused by training. We showed that QSI had the possibility to depict noninvasively the microstructure like muscle fiber type and subtle changes caused by growth and sports characteristics, which previously could only be assessed by biopsy.

Body Motion and Rowing Performance: Association between Hip Angle and Rowing Performance: A Pilot Study.

The importance of aerobic fitness in rowing has been widely studied, and it is accepted that aerobic fitness is a key factor in rowing performance. In contrast, the impact of rowing efficacy, especially rowing form, on rowing performance has not yet been fully elucidated. The present study aimed to investigate this subject via the analysis of hip kinematics and the association of this variable with 2000 m ergometer rowing test performance. Eleven adult male rowers underwent a 2000 m rowing test on an ergometer and the exhaled gas was analyzed. The hip joint angle, the pelvic rotation, and the knee joint angle were measured at the catch position throughout the test. Peak VO2 was strongly associated with the time taken to complete the test (ρ=-0.96, P<0.01), thereby confirming the importance of aerobic capacity in rowing performance. The variance of the hip joint angle of each rower was associated with peak VO2, lean mass, and test time (ρ=-0.72, -0.84, and 0.66, respectively, all P<0.05). Greater knee flexion was accompanied by larger posterior rotation of the pelvis (ρ=0.74, P<0.05), and was negatively associated with hip flexion (ρ=-0.76, P<0.05). Although we cannot confirm whether the consistency of the hip joint angle actually leads to better rowing performance, our results suggest that there are associations between the consistency of the hip joint angle, aerobic capacity, lean mass, and the time taken to complete the 2000 m ergometer rowing test.

Noninvasive technique to evaluate the muscle fiber characteristics using q-space imaging.

BACKGROUND: Skeletal muscles include fast and slow muscle fibers. The tibialis anterior muscle (TA) is mainly composed of fast muscle fibers, whereas the soleus muscle (SOL) is mainly composed of slow muscle fibers. However, a noninvasive approach for appropriately investigating the characteristics of muscles is not available. Monitoring of skeletal muscle characteristics can help in the evaluation of the effects of strength training and diseases on skeletal muscles. PURPOSE: The present study aimed to determine whether q-space imaging can distinguish between TA and SOL in in vivo mice. METHODS: In vivo magnetic resonance imaging of the right calves of mice (n = 8) was performed using a 7-Tesla magnetic resonance imaging system with a cryogenic probe. TA and SOL were assessed. q-space imaging was performed with a field of view of 10 mm × 10 mm, matrix of 48 × 48, and section thickness of 1000 µm. There were ten b-values ranging from 0 to 4244 s/mm2, and each b-value had diffusion encoding in three directions. Magnetic resonance imaging findings were compared with immunohistological findings. RESULTS: Full width at half maximum and Kurtosis maps of q-space imaging showed signal intensities consistent with immunohistological findings for both fast (myosin heavy chain II) and slow (myosin heavy chain I) muscle fibers. With regard to quantification, both full width at half maximum and Kurtosis could represent the immunohistological findings that the cell diameter of TA was larger than that of SOL (P < 0.01). CONCLUSION: q-space imaging could clearly differentiate TA from SOL using differences in cell diameters. This technique is a promising method to noninvasively estimate the fiber type ratio in skeletal muscles, and it can be further developed as an indicator of muscle characteristics.

Maintenance of the paraspinal muscles may protect against radiographic knee osteoarthritis.

BACKGROUND: Knee osteoarthritis (OA) is an increasing health problem worldwide. So far, only obesity and quadriceps weakness are identified as modifiable risk factors for knee OA. Core muscle strengthening is becoming increasingly popular among older adults because of its ability to enhance the activities of daily living during old age. This study investigated the associations of the size and quality of the abdominal trunk muscles with radiographic knee osteoarthritis (RKOA). METHODS: From 2012 to 2016, data were collected from 146 males and 135 females (age 63.9±13.4 years, BMI 23.2±3.8 kg/m2) at annual musculoskeletal examinations, including knee radiographs and body composition analyses, by dual-energy X-ray absorptiometry. Cross-sectional areas of abdominal trunk muscles were measured using a single-slice computed tomography scan image obtained at the level of the umbilicus. RESULTS: The prevalence of RKOA was 21.2% in males and 28.1% in females. Compared to subjects without RKOA, subjects with RKOA were ~6 years older and had smaller paraspinal muscle (38.4±8.7 vs 33.1±10.1 cm2, p<0.01 in males; 24.1±7.1 vs 20.7±7.5 cm2, p<0.05 in females). In contrast, there was no decrease in appendicular or total lean mass, and only in females, BMI and total fat mass (FM) were higher in subjects with RKOA (21.5±3.5 vs 24.5±4.4 kg/m2, 16.7±7.0 vs 20.5±7.7 kg, respectively, both p<0.01). After adjusting for age and sex, smaller cross-sectional area/lower attenuation value of the paraspinal muscles was associated with RKOA (both p<0.05), while greater appendicular or total lean mass as well as greater FM was associated with RKOA. The size and quality of the paraspinal muscles were not associated with knee pain or habitual exercise. CONCLUSION: Small, poor-quality paraspinal muscles may be linked to a higher risk of RKOA, but appendicular or total lean mass was not a good predictor of RKOA.

Characteristics of mucoid Streptococcus pyogenes isolated from two patients with pneumonia in a local community.

Streptococcus pyogenes (Group A Streptococcus, GAS) infections can develop into life-threatening disorders. However, the occurrence of some GAS pneumonia cases is relatively rare in a local community. We report here characteristics of mucoid GAS isolates obtained from the sputum of two patients with pneumonia in a local community. Although case-patients did not have contact with each other, case-patient 1's child and case-patient 2's grandchild attended the same kindergarten where a GAS pharyngitis epidemic had occurred. We conducted phenotypic and genotypic analyses with the GAS isolates from sputum of both patients, to examine (1) colony appearance between the isolates, (2) numerical profile based on API-20 Strep system, (3) similarity to the type strain using 16S rRNA sequencing, (4) emm type (subtype) and emm full-length sequence, (5) sequence type, (6) sic allele, (7) antimicrobial susceptibility result and the resistance determinant, (8) genome profile following a random amplified polymorphic DNA fragments, and (9) pattern of digested DNA fragments by pulse-field gel electrophoresis. These phenotypic and genotypic analyses revealed similar matching between the isolates from both cases. Our findings suggest that when clinicians examine adult patients having infection with the mucoid GAS, they should confirm whether anyone within the same household also developed the infection and need to investigate epidemic situations in local communities, including kindergartens and elementary schools.