In the midst of clustering, we recognized 4 primary teams, from which we highlighted essentially the most related 18 matters.
We current the 18 matters in response to the next 4 features: the variety of publications within the cluster (the scale of the subject), the distribution of the publications based mostly on publication date, the quotation affect of the publications, and the evaluation of the journal rank of publications inside every matter.
The 18 matters are the next:
Soccer and physiology
Muscle physiology: alkalosis and acidosis
Muscle mass acquire and dietary supplementation
Fluid stability and hydration
Dietary consumption and diet data
Willpower of power want of athletes
Bone well being, feminine athlete triad
Physique weight administration
Dietary Methods and human skeletal muscle
Dietary supplementation of nitrates
Oxidative stress and dietary complement use
Dietary complement use and doping
Oxidative stress, irritation, and dietary antioxidants
Train adaptation and dietary methods
Scientometric traits of matters
The dimensions distribution of matters
Primarily based on absolutely the and relative measurement of the matters, which might be based mostly on the variety of publications belonging to a cluster, we are able to get an perception into the importance of the explored matters and analysis traits in sport diet science. These information are displayed in Fig. 3., which, in addition to the variety of publications in every cluster, additionally exhibits their composition by way of the core publications recognized by way of the focused search in addition to of the publications citing, and people cited by the core pattern. When it comes to weight (measurement), essentially the most dominant matter, with ca. 300 publications, is ‘muscle energy enhancement and dietary supplementation’, adopted by matters with about 200–250 publications: ‘carbohydrate metabolism’, ‘oxidative stress and dietary complement use’, ‘train adaptation and dietary methods’, ‘dietary supplementation of nitrates’, ‘dietary methods and human skeletal muscle’. This group is carefully adopted by the subject of ‘bone well being, feminine athlete triad’, ‘dietary consumption and diet data’, and ‘dedication of power want of athletes’, with about 200 publications. The group with 100–150 publications is led by the matters of ‘fluid stability and hydration’, and ‘physique weight administration’, furthermore, right here belong the themes of ‘soccer and physiology’, additionally the ‘hydration technique’, in addition to ‘dietary complement use and doping’. Within the 50–100 vary, the dominant matters with virtually 100 publications are ‘muscle physiology: alkalosis and acidosis’, ‘oxidative stress, irritation and dietary antioxidants’, additionally right here belong the smaller however well-defined matters of ‘intestine microbiota’ and ‘celiac illness’. The total measurement of the matters significantly correlates with their function and significance within the core pattern; that’s, measurement rating additionally displays the extent to which the cluster is of ‘sport physiological’ nature.
Chronological distribution of matters
The distribution by publication date of the publications belonging to the recognized matters, or, to place it one other method, the chronological distribution of every cluster facilitates the evaluation of the traits and relevance of every matter, of their ‘standard’ or ‘winding down’ nature. The distribution of the scale of the matters is summarized in Fig. 4., which exhibits the variety of paperwork belonging to every matter ranging from 2010. Primarily based on this, the pattern graphs within the desk present an summary of the chronological dynamics of the matters. The pattern graphs attest that every matter exhibits a rising tendency (that’s, an increasing number of articles appeared on the given matter prior to now decade), every cluster is at its most measurement within the final examined 12 months (2018). The variations between the matters seem within the traits and sample of the rise. In line with the latter, with a little bit simplification, we observe two sorts of enhance: (1) the subject will increase progressively from the start or center of the examined decade, (2) after a relative ‘stagnation’, the subject exhibits a rising slope in the previous couple of years. Kind (1), a gradual enhance is essentially the most attribute of the matters ‘muscle physiology: alkalosis and acidosis’, ‘dietary methods and human skeletal muscle’, ‘train adaptation and dietary methods’. Kind (2), sudden enhance with a extra reasonable rising slope, unfold during the last 4-5 years, seems in relation with the matters ‘soccer and physiology’, ‘power consumption and diet data’, ‘dietary methods and human skeletal muscle’, ‘fluid stability and hydration’, ‘hydration technique’, ‘oxidative stress and dietary complement use’, ‘dietary complement use and doping’, ‘oxidative stress, irritation and dietary antioxidants’. Within the case of matters with a Kind (2) the slope is rising and usually peaking within the final 2 years, these are the next: ‘muscle energy enhancement and dietary supplementation’, ‘dedication of power want of athletes’, ‘physique weight administration’, ‘intestine microbiota’, and ‘celiac illness’. A ‘distinctive’ cluster, with a considerably totally different sample from the 2 primary varieties is the ‘carbohydrate metabolism’, which, together with some fluctuations, exhibits a gentle output within the matter (additionally with a slight enhance); one other is ‘bone well being and feminine athlete triad’, which additionally exhibits a gentle output with a rising slope within the final examined 12 months.
Quotation affect of matters and journal ranks
Aside from chronological traits, the relevance and scientific significance of matters might be investigated by way of using the next two teams of scientometric indicators: (1) the quotation measures (of the publications) of particular person matters, and (2) the status or rank of publication venues, i.e., journals. Quotation measures present details about the scientific affect exerted by publications inside a subject, thought-about as a basic proxy to the relevance of matters for sport diet science.
As a substitute of the uncooked quotation quantity, correcting for the field- and age-related variations, publications are characterised by their place within the quotation distribution inside the explicit analysis subject, i.e. with the quotation percentile. The clusters with the largest affect are these whose common, that’s, the attribute worth of the related articles is located closest to 100. These with a median above the worth of 75 might be thought-about to have a excessive normal quotation affect (they belong to essentially the most cited, 25%, quotation quartile). Primarily based on this, virtually all of the recognized clusters fall into the excessive quotation measure vary, each by way of their median and of the bulk (minimal 50%) of their publications. The matters with the largest affect are the ‘dietary methods and human skeletal muscle’ and ‘dietary supplementation of nitrates’. A equally excessive composite affect is proven by the matters of ‘soccer and physiology’, ‘carbohydrate metabolism’, ‘bone well being and feminine athlete triad’, ‘physique weight administration’, and ‘intestine microbiota’ (Fig. 5).
The rank of publications, on this case, refers back to the rank and recognition of the publishing journals, with the latter representing, by way of the matters, the standard of data transferred in them. To explain the rank and the standard of the data content material of matters, we utilized the quotation quartile system. The premise of the method is the classification of publications into 4 high quality courses in response to the rank of the publishing journal. The so-called Q1 journals belong to the higher 25% of the journal rank of the sector, Q2 journals belong to the higher 25–50% quartile, Q3 journals are within the decrease 25–50%, and This autumn, within the backside 25%. Determine 6. exhibits the distribution of the articles of the recognized clusters among the many 4 courses for every theme. On this case, additionally, we are able to state that the majority clusters embody publications of top of the range, inasmuch as on common, 50% of their publications are ranked Q1, and nearly all of the remainder of the publications belong to Q2, which can be thought-about a passable high quality rank. ‘Carbohydrate metabolism’, ‘dietary methods and human skeletal muscle’, ‘dietary supplementation of nitrates’ stand out (Fig. 6).
Within the subsequent step of our methodological course of, we utilized the scientometric evaluation of matters, for which we chosen the 4 most important matters and offered their inner construction by way of key thematic relations based mostly on our textual content mining and core doc methodologies. We illustrated the conceptual community of matters with a dendrogram, and we analyzed the 4 matters based mostly on their interconnections from the features of sport diet, sport physiology, sort of sport, dietary dietary supplements, and efficiency diagnostics. The gathering of the 18 matters and their core papers are in Extra file 1. Utilizing a sophisticated bibliometric technique, we obtained the so-called core papers for every analysis matter, essentially the most consultant publications within the cluster (see Extra file 1).
Description of the dietary methods and human skeletal muscle cluster
This matter focuses on the connection between sport efficiency and the metabolic pathways of skeletal muscle cells. Its most frequent subject is the function of PGC-1 alpha transcriptional regulation particularly within the relation to mitochondrial biogenesis, citrate synthesis, endurance efficiency, phosphocreatine because the creatine substrate of efficiency enhancement, the relation of insulin, free fatty acids and fatigue, protein and carbohydrates (to begin with fructose), and likewise in relation to power expenditure and regeneration. Relying on the kind of the examined sport, endurance coaching stands out, however high-intensity interval coaching can also be current with virtually the identical frequency. Of the organic parts, the function of P38 MAPK protein kinase is price emphasizing (Fig. 7).
Description of the dietary supplementation of nitrates matter
The complicated (sport-) physiological focus of the subject is on the relation community of blood circulation, oxidative metabolism and nitrogen metabolism and supplementation (in relation to sport actions). Its major matters are oxygen consumption (associated to the idea of effectivity), fatigue, inorganic nitrate substrate associated to vascular perform, the stimulus-muscle contraction connection, vegetarianism, the enzyme that produces nitrogen oxide substrate, the relation community of hypertension and vasodilatation, irritation and beta-alanine, and bloodstream. Relying on the kind of bodily exercise, this matter is characterised by endurance coaching, particularly, associated to oxidative stress and its biomarkers. The idea of diving response additionally emerged primarily associated to oxygen uptake and consumption and extra barely to respiratory management. Inside additional substrata, sodium nitrite and with decrease frequency, creatine-nitrate appeared. Relating to indices, using the VO2 efficiency indicator was related (Fig. 8).
Description of the carbohydrate metabolism matter
From a sport physiological perspective, this matter additionally revolves across the enchancment of skeletal muscle perform, primarily within the relation to carbohydrate metabolism. Its pivotal ideas and points are lipid oxidation throughout train metabolism processes, nitrogen stability (particularly after consuming), lean physique mass (enhance), cardio capability associated principally to fatigue and endurance coaching, glycemic index, muscle glycogen, and endurance coaching (and carbohydrate absorption). The latter is attribute of the kind of the examined sport and within the phrases of department of sport, biking (timed coaching) and operating emerged. Within the case of the examined substrates, dietary dietary supplements and biologically energetic parts, the function of lipid oxidation (timed biking), and – much less often – catecholamine (operating), sport drinks (biking) and fructose (endurance coaching), and creatine kinase emerged (Fig. 9).
Description of the muscle mass acquire and dietary supplementation matter
The central matters of this cluster are the components of muscle mass acquire and strengthening. Crucial questions of those matters – that the research concentrate on – are the affiliation between muscle restoration and accidents, muscle power, anaerobe threshold, anaerobe capability, cardiorespiratory endurance, and lean physique mass. Categorized by the kind of sport train the 2 main matters are resistance train and high-intensity train associated principally to cardiorespiratory endurance. The subject of dietary complement use can also be important on this cluster. Proteins are an important and nitrogen oxides, nitrates and creatine are additionally appreciable among the many research on substrates and dietary dietary supplements that play an essential function in muscle mass acquire and efficiency enhancement. Carnosine and beta-alanine have a comparatively smaller significance on this matter. On this cluster, electromyography is a frequent analysis technique (Fig. 10).
Vitamins and substrates that appeared within the clusters
Among the many macronutrients, proteins and carbohydrates appeared essentially the most often within the matters. These two vitamins had been studied in response to their normal function in diet and likewise as ergogenic vitamins in sport diet. The function of proteins and amino acids had been assessed within the ‘muscle mass acquire and dietary supplementation’ and the ‘oxidative stress, irritation, and dietary antioxidants’ clusters. Within the carbohydrate metabolism cluster – extra particularly – glucose performs a significant function within the ‘soccer and physiology’ and fructose within the ‘dietary methods and human skeletal muscle’ clusters. Relating to additional vitamins and substrates, beta-alanine, creatine, caffeine, nitrates, and sodium seems often within the analysed publications. The impact of beta-alanine was studied within the ‘muscle physiology: alkalosis and acidosis’, ‘train adaptation and dietary methods’ and the ‘muscle mass acquire and dietary supplementation’ clusters. The function of nitrates was assessed within the ‘dietary supplementation of nitrates’ and within the ‘oxidative stress and dietary complement use’ clusters. Apart from the nitrates, caffeine was additionally analysed in these two latter clusters. Moreover, the subject on the impact of caffeine had a significant function within the ‘dedication of power want of athletes’ and ‘muscle physiology: alkalosis and acidosis’ clusters. The impact of creatine was studied within the ‘physique weight administration’, ‘muscle mass acquire and dietary supplementation’ clusters. The pre- and probiotics had been solely assessed within the ‘intestine microbiota’ cluster. The function of omega-3 fatty acids was analysed as stress and inflammatory marker within the ‘oxidative stress and dietary complement use’ cluster (Desk 1).