Effects of a Multivitamin/multimineral Supplement on Young Males with Physical Overtraining: A Placebo-controlled, Randomized, Double-blinded Cross-over Trial

Objective To investigate the effects of vitamin-mineral supplement on young males with physica overtraining. Methods Two hundred and forty male Chinese field artillery personnel who undertook large scale and endurance military training and were on ordinary Chinese diet were randomized to receive a multivitamin/multimineral supplement or a placebo for 1 week. After a 1-week wash-out period, a cross-over with 1 week course of a placebo or multivitamin/multimineral supplement was conducted. Blood and urine samples were analyzed for adrenal, gonadal and thyroid hormones. In addition, cellular immune parameters （CD3＋, CD3＋CD4＋, CD3＋CD8＋, CD4/CD8, CD3-CD56＋, CD3-CD19＋） were examined and psychological tests were performed before and after the training program and nutrition intervention. Results After a large scale and endurance military training, the participants showed significantly increased thyroid function, decreased adrenal cortex, testosterone and immunological function, and significantly increased somatization, anger and tension. Compared to placebo, multivitamin/ multimineral intervention showed significant effects on functional recovery of the pituitary - adrenal axis, pituitary-gonadal axis, pituitary- thyroid axis and immune system as well as psychological parameters. Conclusion High-intensity military operations have significant impacts on the psychology, physical ability and neuroendocrine-immune system in young males. Appropriate supplementation of multivitamin/multimineral can facilitate the recovery of the psychology, physical ability and neuroendocrine-immune system in young males who take ordinary Chinese diet.

Using Entropy Penalty Term for Improving the Generalization Ability of Multilayer Feedfoward Networks *

Generalization ability is a major problem encountered when using neural networks to find the structures in noisy data sets. Controlling the network complexity is a common method to solve this problem. In this paper, however, a novel additive penalty term which represents the features extracted by hidden units is introduced to eliminate the overtraining of multilayer feedfoward networks. Computer simulations demonstrate that by using this unsupervised fashion penalty term, the generalization ability is greatly improved.

Muscle damage and regeneration: Response to exercise training

Exercise training influences the function of skeletal muscle, modifying fibre structure, metabolism and promoting the release of growth factors and other signalling molecules. The number of satellite cells under the basal lamina of type I and type IIA muscle fibres increases during endurance training and under the basal lamina of both type II fibres during resistance training. An increase in satellite cells is related to several factors expressing different genes and type II muscle fibre hypertrophy. Insulin-like growth factor-I has a role in the hypertrophy of muscle fibres through the stimulation of the differentiation of satellite cells. The increased mitochondrial biogenesis via adenosine myophosphate-activated protein kinase is accompanied by the suppression of myofibrillar protein synthesis through pathways mediated by mitogen-activated protein kinases and the nuclear factor kappa B. Insulin-like growth factor-I expression is higher in type I fibres. Myostatin, the expression inhibitor of muscle hypertrophy, is higher in type II fibres. The proteasome-, lysosome- and Ca2+-mediated protein degradation is more intensive in fibres with higher oxidative capacity. Both, oxidative capacity and satellite cells number in muscle fibres play important roles in skeletal muscle regeneration. In this review, we explore the regeneration capacity changes in different types of skeletal muscle fibres in response to resistance, endurance and overtraining.

Utility of cardiac biomarkers in sports medicine:Focusing on troponin,natriuretic peptides,and hypoxanthine

Evidence-based consensus suggests that physical activity and regular exercise training can reduce modifiable risk factors as well as rate of mortality and morbidity in patients with chronic diseases,such as cardiovascular disease(CVD),diabetes,obesity and cancer.Conversely,long-term exercise training and drastic increase in vigorous physical activity may also cause acute cardiovascular events(e.g.acute myocardial infarction)and deleterious cardiac remodeling,particularly when exercise is performed by unfit or susceptible individuals.There is a reversed J-shaped hormesis-like curve between the duration and intensity of exercise and level of CVD risks.Therefore,it is important for an early detection of cardiac injuries in professional and amateur athletes.Under this context,this article focuses on the use of biomarker testing,an indispensable component in the current clinical practices especially in Cardiology and Oncology.We attempt to justify the importance of using circulating biomarkers in routine practices of Sports Medicine for an objective assessment of CVD events following exercise.Special attentions are dedicated to three established or emerging cardiac biomarkers(i.e.cardiac troponins,natriuretic peptides,hypoxanthine)for myocardial tissue hypoxia/ischemia events,muscle stress,and the consequent cellular necrotic injury.Based on these focused analyses,we propose use of circulating biomarker testing in both laboratory and point-of-care settings with an increasingly broader involvement or participation of team physicians,trainers,coaches,primary care doctors,as well as educated athlete community.This diagnostic approach may improve the quality of medical surveillance and preventive measures on exercise-related CVD risks/outcomes.

Monitoring Competition Jump Load in Division I Female Collegiate Volleyball Athletes

Aim Tracking competition jump data provides a practical approach for assessing external load in volleyball.Purpose The purpose of this study was to analyze competition jump load in collegiate volleyball players.Methods Data from nine National Collegiate Athletic Association(NCAA)Division I female volleyball players from the 2018 and 2019 competitive seasons were analyzed.Jumps were individually assigned,time-stamped,and recorded for height.Jump count and rate overall and at low,moderate,high,and maximal intensities were calculated.One-way ANOVAs were used to assess the variance in mean jump height from all jumps(HT_(all))and top five jump heights from each match(HTtop5)across positions(middle blocker vs.outside hitter vs.right-side hitter),timepoint in season(early vs.mid-vs.late),match length(3-vs.4-vs.5-set match),and Friday/Sunday matches and two-way ANOVAs were used to analyze jump count and rate differences across intensities.Results Significant differences in HTall and HTtop5 across positions(P<0.001)were shown.Main effects were found for jump count and rate by position(P<0.001)and for jump count by match length(P<0.001).Significant intensity×position interactions for jump count and rate by position(P<0.001)and by timepoint(P<0.01)and jump count by match length(P<0.001)were found.No statistically significant variance was observed in HTall or HTtop5 based on timepoint(P>0.05),HTall,HTtop5,or jump rate by match length(P>0.05),or HTall,HTtop5,jump count,or jump rate between Friday/Sunday matches(P>0.05).Conclusion Significant differences in competition jump height and load exist in NCAA Division I female volleyball players.Jump load alterations during training sessions may be warranted to maximize athlete readiness and performance.