Growth patterns of lateral abdominal muscles in adolescent baseball players / 体力科学

The purpose of this study was to determine the differences in the growth patterns of the external oblique (EO), internal oblique (IO), and transversus abdominis (TrA) muscles in adolescence baseball players. The subjects were 17 elementary school students (ES), 56 junior high school students (JS), and 21 high school students (HS) who played baseball. The EO, IO, and TrA muscle thicknesses were imaged using an ultrasound imaging device and analyzed separately on the dominant and non-dominant sides. Curve regression estimation of the relationship between EO, IO, and TrA and chronological age was used to read inflection points. An analysis of covariance was also performed, using body weight as a covariate for comparison with each of the EO, IO, and TrA grades. The inflection point readings showed that TrA was 11.26 years old (p<0.01, R2=0.45) for the dominant side and 10.10 years old (p<0.01, R2=0.46) for the non-dominant side, earlier than the inflection points of EO and IO. Analysis of covariance showed no significant difference in EO between any of the grades. IO showed significantly higher values for muscle thickness as the grade increased, both on the dominant and non-dominant side. TrA was higher for JS among ES and JS and higher for HS among ES and HS on both the dominant and non-dominant sides. EO may growth with increasing body size, while IO is interpreted to increase with increasing age due to the movement of baseball. TrA may grow earlier than EO and IO.

Development pattern of swing speed of batting in youth baseball players / 体力科学

The purpose of this study was to determine the developmental pattern of swing speed in youth baseball players between 6 and 14 years old. A total of 1213 baseball players performed toss batting. Swing speed was measured with a specialized accelerometer. In addition, 618 of the 1213 players were measured for total fat free mass by using Inbody770. In study1, Regression analysis was performed on the relationship between chronological age or height and swing speed, and the extreme values were calculated. Then, an allometric equation based on height was also used to estimate the relative growth of swing speed and total fat free mass and to compare the difference of relative growth patterns between swing speed and total fat free mass in study2. Swing speed was strongly related to both chronological age and height, with cubic regression for the relationship with chronological age and linear for the relationship with height. The regression equation obtained for chronological age was solved and found that developmental rate was maximal at approximately 10.25 years old. Allometric analysis showed that the developmental pattern of swing speed differed from that of fat free mass, with a temporary decline in developmental rate from 153.6 cm to 160.9 cm. Based on the results of this study, further research in youth baseball players would be expected to identify the factors causing sluggish development of swing speed as well as to develop an exercise program for improving batting ability.

Similar viral loads in Omicron infections regardless of vaccination status

BackgroundAlthough SARS-CoV-2 booster vaccinations are underway, breakthrough infections with Omicron variants are occurring. This study analyzed associations between Omicron sublineage (BA.1.1 and BA.2) viral load and vaccination history. MethodsViral loads in nasopharyngeal swabs were evaluated by quantitative real-time PCR, and the virus strain was evaluated by whole-genome analysis or TaqMan assay. ResultsA total of 611 patients positive for an Omicron SARS-CoV-2 variant were included; 199 were unvaccinated, 370 had received two vaccine doses, and 42 had received three doses. Similar viral loads and Ct values of BA.1.1 and BA.2 were detected regardless of vaccination history. No correlations between age and BA.1.1 and BA.2 viral load were observed. ConclusionOmicron-infected patients who had received a third vaccine dose had viral loads similar to patients with two doses or who were unvaccinated.

SARS-CoV-2 Omicron sublineage BA.2 replaces BA.1.1: genomic surveillance in Japan from September 2021 to March 2022

ObjectiveThe new emerging Omicron strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is currently spreading worldwide. We aimed to analyze the genomic evolution of the shifting Omicron virus subtypes. MethodsThe study included 1,297 individuals diagnosed as SARS-CoV-2 positive by PCR test or antigen quantification test from September 2021 to March 2022. Samples were analyzed by whole genome sequencing analysis (n=489) or TaqMan assay (n=808). ResultsAfter the outbreak of the SARS-CoV-2 Delta strain, the Omicron strain spread rapidly in Yamanashi, Japan. BA.1.1 was the predominant sublineage of the Omicron strain from January to mid-February 2022, but the number of cases of sublineage BA.2 began to increase after mid-February, and this sublineage was shown to have replaced BA.1.1 by the end of March 2022. We observed higher viral and antigen levels of sublineage BA.2 than of sublineage BA.1.1 in nasopharyngeal swab samples. However, no difference in viral load by patient age was apparent between sublineages BA.1.1 and BA.2. ConclusionsA transition from sublineage BA.1.1 to sublineage BA.2 was clearly observed over approximately one month. Omicron sublineage BA.2 was found to be more transmissible owing to its higher viral load regardless of patient age.

Classification of Omicron BA.1, BA.1.1 and BA.2 sublineages by TaqMan assay consistent with whole genome analysis data

ObjectiveRecently, the Omicron strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread and replaced the previously dominant Delta strain. Several Omicron sublineages (BA.1, BA.1.1 and BA.2) have been identified, with in vitro and preclinical reports showing that the pathogenicity and therapeutic efficacy differs between BA.1 and BA.2. We sought to develop a TaqMan assay to identify these subvariants. MethodsA TaqMan assay was constructed for rapid identification and genotyping of Omicron sublineages. We analyzed three characteristic mutations of the spike gene, {Delta}69-70, G339D and Q493R, by TaqMan assay. The accuracy of the TaqMan assay was examined by comparing its results with the results of whole genome sequencing (WGS) analysis. ResultsA total of 169 SARS-CoV-2 positive samples were analyzed by WGS and TaqMan assay. The 127 samples determined as BA.1/BA.1.1 by WGS were all positive for {Delta}69-70, G339D and Q493R by TaqMan assay. Forty-two samples determined as BA.2 by WGS were negative for {Delta}69-70 but positive for G339D and Q493R by TaqMan. The concordance rate between WGS and the TaqMan assay was 100% (169/169). ConclusionTaqMan assays targeting characteristic mutations are useful for identification and discrimination of Omicron sublineages.