Age- and activity-related differences in the abundance of Myosin essential and regulatory light chains in 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

The effects of knee flexion on muscle activation and performance during chin-up exercise

Background and Study Aim Chin-up is an exercise that is done to improve the strength, muscular endurance and size of the upper back and arm muscles. There are many ways to perform chin-up exercises including by performing it with different forms of knee flexion. This study aims to examine the effects of knee flexion on muscle activation and performance during chin-up exercise. Material and Methods a total of twenty-one healthy trained male (age 20-25 years old) were recruited and were instructed to perform chin-up exercises in three knee conditions: i) knee fully flexed, ii) partial knee flexed, and iii) straight knee. Chin-up performance was measured by the number of repetitions performed in three sets. Muscle activation was measured using EMG and taken from latissimus dorsi (LD), posterior deltoid (PD), and biceps brachii (BB) during both concentric and eccentric phase. One-way repeated measure Analysis of Variances (ANOVA) were conducted to compare the muscle activation and number of repetitions performed across the three variation of chin-up exercise. Results Findings showed that during the concentric phase, BB recorded higher muscle activation during straight knee compared to knee fully flexed and partial knee flexed, p < .05. In addition, chin-up performance during straight knee and partial knee flexed were better than knee fully flexed, p < .05. Conclusions The results of this study demonstrated the importance to consider techniques manipulation during exercises due to its effects on acute responses as shown by number of repetitions and muscle activation in this study that might also affect the long-term outcomes

Pre-Competitive Anxiety of Malaysian Premier League and University Football Players

This study aimed to identify the level of state anxiety among football players of a Malaysian premier league and a university football players. This study involved 40 players aged between 18 to 32 years old. The questionnaire used in this study was Competitive State Anxiety Inventory-2 Reverse Survey (CSAI-2R) to measure the level of athlete's somatic anxiety, cognitive anxiety and self-confidence. The findings showed that the premier league players has a lower level of somatic and cognitive anxiety than the university players. Premier league players also were shown to have higher levels of self-confidence. Based on the findings, experience and achievement level are the contributing factors in determining the level of anxiety and increasing self-confidence. The more experience and skills the athlete has, the easier it is for athletes to control the level of anxiety. © BEIESP

Вплив навантаження натільними обважнювачами під час виконання протоколу розминки на біомеханіку прямого удару ногою в тхеквондо

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&nbsp;±&nbsp;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.Мета дослідження. Це дослідження має на меті вивчення та визначення впливу навантаження натільними обважнювачами під час виконання протоколу розминки на механіку руху прямого удару ногою та активацію м’язів. Матеріали та методи. У дослідженні брали участь двадцять п’ять університетських спортсменів чоловічої статі (N = 25, зріст = 174,00 ± 4,76 см, маса = 75,93 ± 13,64 кг, вік = 22,57&nbsp;±&nbsp;1,36 року), які займаються тхеквондо. До стегон і гомілок учасників були прикріплені натільні обважнювачі з навантаженням 0%, 5% та 10% маси тіла спортсменів. Оцінювали кінематику, кінетику та активацію м’язів під час виконання прямого удару ногою. Результати. Загалом результати показали відсутність значних відмінностей між різними навантаженнями натільними обважнювачами в показниках кінематики, кінетики та активації м’язів під час виконання руху прямого удару ногою. Результати також показали відсутність шкідливого впливу внаслідок носіння натільних обважнювачів під час занять розминкою. Результати є дещо несподіваними, оскільки було висунуто гіпотезу, що застосування обважнювачів впливатиме на механіку удару ногою та активацію м’язів. Натільні обважнювачі не підвищили показник виконання удару ногою, якому відповідає швидкість удару ногою. Це, можливо, зумовлено використовуваними відсотковими частками навантаження, які вважаються такими, що не знижують показник виконання, що показує, що ці натільні обважнювачі можна використовувати під час розминки на тренувальних заняттях як доповнення до тренувань з обтяженнями. Висновки. Ми рекомендуємо в майбутніх дослідженнях вивчити хронічні ефекти натільних обважнювачів як спеціальних засобів, які використовуватимуть для покращення показників виконання ударів ногою в тхеквондо