Two-dimensional gel electrophoresis provides robust comparative analysis of skeletal muscle, but this technique is laborious and limited by its inability to resolve all proteins. In contrast, orthogonal separation by SDS-PAGE and reverse-phase liquid chromatography (RPLC) coupled to mass spectrometry (MS) affords deep mining of the muscle proteome, but differential analysis between samples is challenging due to the greater level of fractionation and the complexities of quantifying proteins based on the abundances of their tryptic peptides. Here we report simple, semi-automated and time efficient (i.e., 3 h per sample) proteome profiling of skeletal muscle by 1-dimensional RPLC electrospray ionisation tandem MS. Solei were analysed from rats (n = 5, in each group) bred as either high- or low-capacity runners (HCR and LCR, respectively) that exhibited a 6.4-fold difference (1,625 ± 112 m vs. 252 ± 43 m, p < 0.0001) in running capacity during a standardized treadmill test. Soluble muscle proteins were extracted, digested with trypsin and individual biological replicates (50 ng of tryptic peptides) subjected to LC-MS profiling. Proteins were identified by triplicate LC-MS/MS analysis of a pooled sample of each biological replicate. Differential expression profiling was performed on relative abundances (RA) of parent ions, which spanned three orders of magnitude. In total, 207 proteins were analysed, which encompassed almost all enzymes of the major metabolic pathways in skeletal muscle. The most abundant protein detected was type I myosin heavy chain (RA = 5,843 ± 897) and the least abundant protein detected was heat shock 70 kDa protein (RA = 2 ± 0.5). Sixteen proteins were significantly (p < 0.05) more abundant in HCR muscle and hierarchal clustering of the profiling data highlighted two protein subgroups, which encompassed proteins associated with either the respiratory chain or fatty acid oxidation. Heart-type fatty acid binding protein (FABPH) was 1.54-fold (p = 0.0064) more abundant in HCR than LCR soleus. This discovery was verified using selective reaction monitoring (SRM) of the y5 ion (551.21 m/z) of the doubly-charged peptide SLGVGFATR (454.19 m/z) of residues 23–31 of FABPH. SRM was conducted on technical replicates of each biological sample and exhibited a coefficient of variation of 20%. The abundance of FABPH measured by SRM was 2.84-fold greater (p = 0.0095) in HCR muscle. In addition, SRM of FABPH was performed in vastus lateralis samples of young and elderly humans with different habitual activity levels (collected during a previous study) finding FABPH abundance was 2.23-fold greater (p = 0.0396) in endurance-trained individuals regardless of differences in age. In summary, our findings in HCR/LCR rats provide protein-level confirmation for earlier transcriptome profiling work and show LC-MS is a viable means of profiling the abundance of almost all major metabolic enzymes of skeletal muscle in a highly parallel manner. Moreover, our approach is relatively more time efficient than techniques relying on orthogonal separations, and we demonstrate LC-MS profiling of the HCR/LCR selection model was able to highlight biomarkers that also exhibit differences in trained and untrained human muscle.

Traditional methods for phenotyping skeletal muscle (e.g., immunohistochemistry) are labor-intensive and ill-suited to multixplex analysis, i.e., assays must be performed in a series. Addressing these concerns represents a largely unmet research need but more comprehensive parallel analysis of myofibrillar proteins could advance knowledge regarding age- and activity-dependent changes in human muscle. We report a label-free, semi-automated and time efficient LC-MS proteomic workflow for phenotyping the myofibrillar proteome. Application of this workflow in old and young as well as trained and untrained human skeletal muscle yielded several novel observations that were subsequently verified by multiple reaction monitoring (MRM). We report novel data demonstrating that human ageing is associated with lesser myosin light chain 1 content and greater myosin light chain 3 content, consistent with an age-related reduction in type II muscle fibers. We also disambiguate conflicting data regarding myosin regulatory light chain, revealing that age-related changes in this protein more closely reflect physical activity status than ageing per se. This finding reinforces the need to control for physical activity levels when investigating the natural process of ageing. Taken together, our data confirm and extend knowledge regarding age- and activity-related phenotypes. In addition, the MRM transitions described here provide a methodological platform that can be fine-tuned to suite multiple research needs and thus advance myofibrillar phenotyping.

We investigated whether diurnal differences in muscle force output are associated with the post-translational state of muscle proteins. Ten physically active men (mean ± SD; age 26.7 ± 3.7 y) performed experimental sessions in the morning (08:00 h) and evening (17:00 h), which were counterbalanced in order of administration and separated by at least 72 h. Knee extensor maximal voluntary isometric contraction (MVIC) force and peak rate of force development (RFD) were measured, and samples of vastus lateralis were collected immediately after exercise. MVIC force was greater in the evening (mean difference of 67 N, 10.2%; p < 0.05). Two-dimensional (2D) gel analysis encompassed 122 proteoforms and discovered 6 significant (p < 0.05; false discovery rate [FDR] = 10%) diurnal differences. Phosphopeptide analysis identified 1693 phosphopeptides and detected 140 phosphopeptides from 104 proteins that were more (p < 0.05, FDR = 22%) phosphorylated in the morning. Myomesin 2, muscle creatine kinase, and the C-terminus of titin exhibited the most robust (FDR < 10%) diurnal differences. Exercise in the morning, compared to the evening, coincided with a greater phosphorylation of M-band-associated proteins in human muscle. These protein modifications may alter the M-band structure and disrupt force transmission, thus potentially explaining the lower force output in the morning.

The aim of this study was to determine and compare the muscle activation during unilateral and bilateral biceps curl exercises. Thirty recreationally active, resistance-trained men (age: 20-23 years old) were recruited as research participants. Participants were asked to perform biceps curl exercise using 85% of their 1RM value unilaterally and bilaterally in a randomized order. Muscle activation of biceps brachii and triceps brachii were obtained during the movement using electromyography method. Repeated measure analysis of variance (ANOVA) was conducted to compare the muscle activations between both unilateral and bilateral biceps curl. Results showed that no siginificant differences were found on both biceps brachii and triceps brachii muscle activation between both biceps curl methods. Despite our prediction that unilateral exercise create more instability to movement that will cause more muscle activation, it was not found in this study. The simple movement during this bicep curl exercise might be the possible reason of no differences that existed.

Research purpose. This study aims to examine and determine the effect of wearable resistance loading during warm-up protocol on front kick movement mechanics and muscle activation. Materials and methods. Twenty-five (N = 25, height = 174.00 ± 4.76 cm, weight = 75.93 ± 13.64 kg, age = 22.57 ± 1.36 years) male university taekwondo athletes were recruited as participants of the study. Wearable resistance with loading of 0%, 5% and 10% of the athletes’ body mass were attached to participants’ thigh and shank. Kinematics, kinetics and muscle activation during front kick were assessed. Results. Overall, the results showed that there were no significant differences found between different WR loading in kinematics, kinetics and muscle activation during front kick movement. The results reflected that there were no detrimental effects of wearing wearable resistance during warm-up sessions. The findings are somewhat surprising as it was hypothesized that WR loading would produce effects on the mechanics of kicking and muscle activation. Wearable resistance did not increase kicking performance which was reflected by kicking velocity. This might be due to percentage of loading used which are seen as not reducing the performance, which reflects that the wearable resistance can be used during warm-up in training sessions as an add-on to resistance training. Conclusions. We suggest that future studies should examine the chronic effects of wearable resistance as specific tools to be used in enhancing the performance of taekwondo kicks.

Kajian ini mengkaji pelaksanaan pengajaran Pendidikan Jasmani bagi Pendidikan Khas (Masalah Pembelajaran) di sekolah rendah dan membangunkan model pengajaran yang dicadangkan untuk guru. Pendekatan kuantitatif digunakan, melibatkan 242 murid dan 175 guru dari sekolah rendah di bawah Program Pendidikan Khas Integrasi (PPKI) di Kuala Lumpur. Analisis statistik deskriptif digunakan untuk memahami demografi responden dan mengenal pasti pendekatan pengajaran yang sesuai, manakala ujian Mann-Whitney U dan Korelasi Spearman’s Rho menentukan perbezaan dan hubungan dalam minat, tingkah laku, kemahiran, dan pengetahuan murid. Dapatan menunjukkan tiada perbezaan signifikan dalam minat hadir ke sekolah berdasarkan jantina (p = .683) dan tahun (p = .547). Namun, perubahan tingkah laku menunjukkan perbezaan signifikan berdasarkan jantina (p = .000) dan tahun (p = .014). Penguasaan kemahiran dan peningkatan pengetahuan turut mencatatkan perbezaan signifikan berdasarkan jantina (p = .000, p = .044) dan tahun (p = .001, p = .009). Faktor persekitaran (r = .404) dan saiz kelas (r = .191) mempengaruhi minat hadir ke sekolah. Pendekatan induktif (min = 4.43), strategi berpusatkan guru (min = 4.34), Pentaksiran Berasaskan Sekolah (min = 4.23), kaedah demonstrasi (min = 4.47), teknik permainan (min = 4.61), dan soal jawab (min = 4.33) dikenalpasti sebagai strategi berkesan. Kajian ini mencadangkan panduan pengajaran sistematik untuk meningkatkan keberkesanan pengajaran Pendidikan Jasmani di sekolah rendah.