Mind the Gap: Comparison of External Load and Load Variation Between a Reserve Team in a 1-Game Week Microcycle and Its First Team in a 2-Game Week Microcycle Within an Elite Professional Soccer Club.

ABSTRACT: Carpels, T, Scobie, N, Macfarlane, NG, and Kemi, OJ. Mind the gap: comparison of external load and load variation between a reserve team in a 1-game week microcycle and its first team in a 2-game week microcycle within an elite professional soccer club. J Strength Cond Res 38(5): e235-e242, 2024-The aim of this study was to quantify and compare weekly external load and within-week load variation of reserve team players (RES) in a 1-game week microcycle to first team players (FT) in a 2-game week microcycle within the same professional soccer club. External load data were collected between 2017 and 2020 for the following parameters: duration, total distance (TD), total high-speed distance (THSD; >19.8 km·h -1 ), high-speed distance (HSD; 19.8-25.2 km·h -1 ), sprint distance (SD; >25.2 km·h -1 ), number of sprints (number of efforts >25.2 km·h -1 ), number of high-speed efforts (number of HS efforts >19.8 km·h -1 ), meters per minute (m·min -1 ), and high-speed meters per minute (HS m·min -1 ). First team players were subcategorized into starters (ST) and nonstarters (NST). Intergroup differences in cumulative weekly load and weekly load patterns were statistically analyzed, whereas training monotony (TM) was quantified to assess intragroup, within-week, load variation. Reserve team players showed similar weekly loads to ST, apart from significant differences ( p < 0.005) in duration (8%), TD (21%), and HS efforts (16%). Similar to ST, RES showed greater values than NST ( p < 0.0005) for duration (10%), TD (9%), THSD (30%), HSD (26%), SD (45%), sprints (40%), and HS efforts (22%). Weekly patterns in RES were different from ST and NST ( p < 0.05). Training monotony was highest for NST for all parameters, apart from the number of sprints. Reserve team players need to be prepared to cope with cumulative weekly loads and the lack of recovery between games that ST face. However, when RES become NST, effective loading strategies need to be designed within the limits of 2-game week microcycles to ensure continuous development.

Graduate prospects explain undergraduate program standing in university league sports science tables.

UK university undergraduate programs are compared by independent subject-specific rankings (Complete, Guardian, and Times), based on data from the National Student Survey, Higher Education Statistics Agency, Universities and Colleges Admissions Service, Research Excellence Framework, and the universities. The sports and exercise science program at the University of Glasgow has steadily risen to currently rank as the top UK program. This investigation aimed to identify the underlying factors that explain this. Therefore, we obtained underlying scores for entry standard, student satisfaction, research foundation, graduate prospects, staff-to-student ratio, expenditure/student, continuation, program support to students, and teaching quality from the ranking providers for years 2010-2024, and statistically modeled which factors significantly affected the rankings. We found that entry standards and graduate prospects strongly correlated significantly with ranking results. Principal component analysis indicated that a model of graduate prospects and entry standards explained 66.2% of the variance in ranking results. Multiple linear regression with all underlying factors included in the model indicated they explained 78% (R2 = 0.78) of the total variance, while stepwise elimination of insignificant factors identified graduate prospects as the sole factor that significantly affected outcome by explaining 71% (R2 = 0.71) of the variance. Therefore, the primary predictor of ranking success in UK university league tables for sports science is graduates' professional success (graduate prospects).NEW & NOTEWORTHY University rankings are used by applicants and stakeholders to judge programs, including undergraduate studies. In the rankings, undergraduate UK programs are compared and contrasted against each other based on how they score for criteria that affect student life and future prospects. Here, we determined the relative influence of those criteria and found that graduate prospects, how students professionally benefit from their study after graduation, is the factor that matters most for the ranking results.

The influence of relative playing area and player numerical imbalance on physical and perceptual demands in soccer small-sided game formats.

PURPOSE: This study aimed to examine physiological, mechanical and perceptual loading in small-sided games using different relative playing areas with balanced and unbalanced player numbers. METHODS: Data were collected in twelve elite youth male soccer players and included heart rate and standard time-motion outputs using commercial GPS. RESULTS: The data demonstrated higher cardiovascular, physical and perceptual demands with increasing pitch size (e.g. average HR was 88.7 vs. 86.7% HRmax with 8 vs. 2 high-intensity acceleration in medium vs. small pitch formats. The largest pitch format resulted in a greater accumulation of high-intensity distance (47 ± 30 m), higher peak velocity (25.2 ± 1.6 km.h-1) and a higher distance and frequency of accelerations (35 ± 9 m and 8 ± 3) compared with the smallest pitch (all p < 0.01). In unbalanced games, there was significantly greater average heart rate in the overloaded team (84.4 ± 4.9 vs. 80.4 ± 4.8% HRmax in 4 v. 6). CONCLUSION: These data suggest that different game formats including numerical imbalance could be prescribed for squad management to target conditioning stimuli for specific players (e.g. to target a higher training load for players that do not get consistent match exposure).

The influence of season phase on multivariate load relationships in professional youth soccer.

The purpose of this research was to assess relationships between subjective and external measures of training load in professional youth footballers, whilst accounting for the effect of the stage of the season. Data for ratings of perceived exertion (RPE) and seven global positioning systems (GPS) derived measures were collected from 20 players (age = 17.4 ± 1.3 yrs, height = 178.0 ± 8.1 cm, mass = 71.8 ± 7.2 kg) across a 47-week season. The season was categorised by a pre-season phase, and two competitive phases (Comp1, Comp2). The structure of the data were investigated using principal component analysis. An extraction criterion of component with eigenvalues ≥1.0 was used. Two components were retained for the pre-season period explaining a cumulative variance of 77.1%. Single components were retained for both Comp1 and Comp2 explaining 73.3% and 74.3% of variance, respectively. Identification of single components may suggest that measures are related and can be used interchangeably, however these interpretations should be considered with caution. The identification of multiple components in the pre-season phase suggests that univariate measures may not be sufficient when considering load experienced. These results suggest that factoring load based on measures of volume and intensity should be considered.

Relationship Between Subjective and External Training Load Variables in Youth Soccer Players.

PURPOSE: To quantify and describe relationships between subjective and external measures of training load in professional youth soccer players. METHODS: Data from differential ratings of perceived exertion (dRPE) and 7 measures of external training load were collected from 20 professional youth soccer players over a 46-week season. Relationships were described by repeated-measures correlation, principal component analysis, and factor analysis with oblimin rotation. RESULTS: Significant positive (.44 ≤ r ≤ .99; P < .001) within-individual correlations were obtained across dRPE and all external training load measures. Correlation magnitudes were found to decrease when training load variables were expressed per minute. Principal component analysis provided 2 components, which described 83.3% of variance. The first component, which described 72.9% of variance, was heavily loaded by all measures of training load, while the second component, which described 10.4% of the variance, appeared to have a split between objective and subjective measures of volume and intensity. Exploratory factor analysis identified 4 theoretical factors, with correlations between factors ranging from .5 to .8. These factors could be theoretically described as objective volume, subjective volume, objective running, and objective high-intensity measures. Removing dRPE measures from the analysis altered the structure of the model, providing a 3-factor solution. CONCLUSIONS: The dRPE measures are significantly correlated with a range of external training load measures and with each other. More in-depth analysis showed that dRPE measures were highly related to each other, suggesting that, in this population, they would provide practitioners with similar information. Further analysis provided characteristic groupings of variables.

Youth-to-Senior Transition in Elite European Club Soccer.

The priority for soccer academies is to develop youth players that graduate and transfer directly to their senior squads. The aim of this study was to assess the effectiveness of this direct youth-to-senior pathway by examining the extent to which club-trained players (CTPs) are currently involved in elite male European soccer. Relevant demographic longitudinal studies between 2009 and 2020 conducted by the International Centre for Sports Studies Football Observatory were analysed. The main findings were that the proportion of CTPs in senior squads has decreased from 23% to 17% over this time period, while the proportion of expatriates (EXPs) has increased from 35% to 42%. Moreover, clubs resorted more frequently to making new signings (NS, i.e. association-trained players (ATPs) and/or EXPs), with squad proportion increasing from 37% to 44%, while only launching one debutant (DBT, i.e. CTP with no previous senior experience) on average per season. Similar trends are observed in the evolution of playing time: while the fielding of CTPs remained constant (15%), EXPs and NS are fielded increasingly more (49% and 36%, respectively), despite a positive relationship between CTP match fielding and league ranking, with a Spearman Rank correlation r = 0.712 (95% confidence interval [0.381-0.881]), p < 0.01. In conclusion, young talents are still provided opportunities; however, these are limited and increasingly less frequent at their parent clubs. This potentially suggests a dysfunctional direct youth-to-senior development pathway.

Adiponectin, in contrast to leptin, is not associated with body mass index, waist circumference and HOMA-IR in subjects of a west-African population.

Factors associated with plasma levels of adiponectin and leptin were studied in adult subjects without diabetes from Cotonou in Benin (West-Africa). Seventy (70) men and 45 women were included in the study. Anthropometric variables were measured and a venous blood sample was drawn from each subject, after an overnight fasting period, for measurement of plasma glucose, insulin, leptin, and adiponectin levels. HOMA-IR was determined to assess insulin resistance. Adiponectin and leptin levels were higher in women than in men (with adiponectin 18.48 ± 12.77 vs.7.8 ± 10.39 µg/mL, P < 0.0001, and leptin 30.77 ± 19.16 vs. 8.66 ± 8.24 ng/mL, P < 0.0001). Fasting insulin level and HOMA-IR were also higher in the females. Hyperleptinemia was observed in 66,96% of subjects and hypoadiponectinemia was present in 44.35% of subjects. In both men and women, leptin correlated with age (r = 0.2; P = 0.02), BMI (r = 0.572; P < 0.0001), waist circumference (r = 0.534; P < 0.0001), fasting insulin (r = 0.461; P < 0.001), and HOMA-IR (r = 0.430; P < 0.0001). No significant correlation was observed for adiponectin levels with these variables. Only in women, adiponectin was inversely correlated with fasting glucose (r = -0.423; P < 0.004). These data confirm previous descriptions of leptin but suggest that variations in factors determining serum adiponectin levels observed between ethnicities could also been seen between populations from the same ethnicity.

Contextual effects on activity profiles of domestic field hockey during competition and training.

Game context is widely accepted to influence performance but most data available is 'categorical' and addresses performance rather than activity. This study assessed direct effects of opposition and team ranking in field hockey to establish influences on activity. One hundred and eight (n=108) female field hockey players (age 16-39 years) participated, giving 186 competition and 48 training analyses. Team average distance (mean ± SD) observed in a mid-ranked team during competition ranged from 5,949 ± 611 to 7,719 ± 257 m demonstrating an opposition rank effect (Pearson's r=.71; adjusted R(2)=.42). However, multiple linear regression analysis demonstrated a stronger relationship in lower ranked teams (Pearson's r=.99; adjusted R(2)=.97 through 3-9). In contrast, no team rank effect was observed during randomly monitored competition where team average distance ranged from 5,177 ± 444 to 7,316 ± 241 m (Pearson's r=.15 and adjusted R(2)=.12). In training, however, a team rank effect was observed in distance-related performance indicators where team average distance during small-sided games ranged from 5,877 ± 188 to 3,551 ± 193 m drill (per 70 min) with Pearson's r=.95 and adjusted R(2)=.87. The presence of contextual effects has significant practical implications for team sports where the training load assumed from competition may be overestimated.

Analysis of international competition and training in men's field hockey by global positioning system and inertial sensor technology.

This study assessed the relative demands of elite field hockey training and competition to determine whether familiar exercise prescription strategies provide an appropriate training stimulus. Sixteen elite male field hockey players (age, 25 ± 4 years; body mass, 70.9 ± 6.6 kg; and maximal oxygen consumption, 61.0 ± 2.1 ml·kg·min [mean ± SD]) participated in the study. Seventy-five elite level competition and 37 training analyses from 8 games and 4 training sessions were obtained. Training duration was longer than competition and covered a greater total distance (109 ± 2.5 vs. 74 ± 0.3 minutes and 7318 ± 221 vs. 5868 ± 75 m; p < 0.001 in both). The distance covered sprinting and running at high intensity was not different between training and competition (114 ± 6 vs. 116 ± 9 m when sprinting and 457 ± 6 vs. 448 ± 7 m for high-intensity running). More high-intensity accelerations were performed during training than in competition (37 ± 3 vs. 20 ± 2). Despite having lower predicted aerobic capacity and covering less distance in competition than in some previous studies, these data support the suggestion that it is high-intensity activity that differentiates international level competition and further suggests that international players can replicate the intensity of competition during small-sided games.

Physiological responses to an intensified period of rugby league competition.

This study investigated the physiological responses to an intensified period of rugby league competition and the subsequent impact on match performance. The participants were 7 rugby league players competing in an international student tournament. The tournament involved three 80-minute games over a 5-day period, with 48 hours between each match. Baseline measures of upper and lower body neuromuscular functions via a plyometric press-up (PP) and countermovement jump (CMJ), respectively (peak power and peak force were measured), blood creatine kinase (CK), and perceptions of well-being were assessed with a questionnaire. These measures were repeated every morning of the competition; neuromuscular fatigue and CK were additionally assessed within 2 hours after the cessation of each game. During each match, player movements were recorded via global positioning system units. There were meaningful reductions in upper (effect size [ES] = -0.55) and lower body (ES = -0.73) neuromuscular functions, and perceptual well-being (ES = -1.56) and increases in blood CK (ES = 2.32) after game 1. These changes increased in magnitude as the competition progressed. There were large reductions in the relative distance covered in high-speed running (ES = -1.49) and maximal accelerations (ES = -0.85) during game 3. Additionally, moderate reductions in the percentage of successful tackles completed were observed during game 3 (ES = -0.59). Collectively, these results demonstrate that during an intensified period of rugby league competition, characterized by only 48 hours between matches, fatigue will accumulate. This cumulative fatigue may compromise high-intensity match activities such as high-speed running, accelerations, and tackling. Furthermore, CMJs and PPs appear to be sensitive measures for monitoring neuromuscular function in rugby league players.

Fat oxidation, fitness and skeletal muscle expression of oxidative/lipid metabolism genes in South Asians: implications for insulin resistance?

BACKGROUND: South Asians are more insulin resistant than Europeans, which cannot be fully explained by differences in adiposity. We investigated whether differences in oxidative capacity and capacity for fatty acid utilisation in South Asians might contribute, using a range of whole-body and skeletal muscle measures. METHODOLOGY/PRINCIPAL FINDINGS: Twenty men of South Asian ethnic origin and 20 age and BMI-matched men of white European descent underwent exercise and metabolic testing and provided a muscle biopsy to determine expression of oxidative and lipid metabolism genes and of insulin signalling proteins. In analyses adjusted for age, BMI, fat mass and physical activity, South Asians, compared to Europeans, exhibited; reduced insulin sensitivity by 26% (p = 0.010); lower VO2max (40.6±6.6 vs 52.4±5.7 ml x kg(-1) x min(-1), p = 0.001); and reduced fat oxidation during submaximal exercise at the same relative (3.77±2.02 vs 6.55±2.60 mg x kg(-1) x min(-1) at 55% VO2max, p = 0.013), and absolute (3.46±2.20 vs 6.00±1.93 mg x kg(-1) x min(-1) at 25 ml O(2) x kg(-1) x min(-1), p = 0.021), exercise intensities. South Asians exhibited significantly higher skeletal muscle gene expression of CPT1A and FASN and significantly lower skeletal muscle protein expression of PI3K and PKB Ser473 phosphorylation. Fat oxidation during submaximal exercise and VO2max both correlated significantly with insulin sensitivity index and PKB Ser473 phosphorylation, with VO2max or fat oxidation during exercise explaining 10-13% of the variance in insulin sensitivity index, independent of age, body composition and physical activity. CONCLUSIONS/SIGNIFICANCE: These data indicate that reduced oxidative capacity and capacity for fatty acid utilisation at the whole body level are key features of the insulin resistant phenotype observed in South Asians, but that this is not the consequence of reduced skeletal muscle expression of oxidative and lipid metabolism genes.

Increase in serum adiponectin concentration in patients with heart failure and cachexia: relationship with leptin, other cytokines, and B-type natriuretic peptide.

AIMS: Adiponectin is a fat-derived hormone involved in the regulation of metabolism. Adiponectin concentration is inversely related to body weight and, in animals, causes weight loss. We, therefore, measured adiponectin concentration in patients with heart failure (HF) and cachexia. METHODS AND RESULTS: Serum adiponectin concentrations were measured in three groups of patients with coronary artery disease (CAD): (i) HF, reduced left ventricular systolic function, and cachexia (n = 10); (ii) HF, reduced systolic function but no cachexia (n = 20); (iii) HF-controls-patients with CAD, no HF, and preserved systolic function (n = 10); and in a healthy control group (n = 7). Patients with HF and cachexia had higher concentrations of adiponectin [23.8 (10.2-37.2) microg/mL] than all other groups: HF-no cachexia 8.1 (0.5-16.6) microg/mL; CAD-controls 7.1 (0.4-13.5) microg/mL; and healthy controls 8.7 (2.5-16.8) microg/mL) (P < 0.05 for each comparison). Adiponectin correlated negatively with body mass index, percentage of body fat, waist circumference and insulin resistance, and positively with B-type natriuretic peptide (BNP) and tumour necrosis factor-alpha. CONCLUSION: Cachexia in HF is associated with an increase in adiponectin concentration. This may represent preservation of the physiological response to change in body fat but might also suggest that adiponectin plays a role in the pathogenesis of cachexia. The correlation between BNP and adiponectin also raises the possibility that the former might increase the secretion of the latter.

Angiotensin-converting-enzyme gene polymorphisms, smoking and chronic obstructive pulmonary disease.

While tobacco smoking is the main risk factor for chronic obstructive pulmonary disease (COPD) only a fraction of smokers go on to develop the disease. We investigated the relationship between the insertion (I)--deletion (D) polymorphisms in the Angiotensin converting enzyme (ACE) gene and the risk of developing COPD in smokers by determining the distribution of the ACE genotypes (DD, ID and II) in 151 life-long male smokers. 74 of the smokers had developed COPD (62 +/- 2 years; FEV1 44 +/- 6% reference) whereas the rest retained normal lung function (56 +/- 2 yrs; FEV1 95 +/- 3% reference). In addition, we genotyped 159 males recruited randomly from the general population. The prevalence of the DD genotype was highest (p = 0.01) in the smokers that developed COPD and its presence was associated with a 2-fold increase in the risk for COPD (OR 2.2; IC95% 1.1 to 5.5). Surprisingly, the 151 individuals in the smoking population did not demonstrate Hardy-Weinberg equilibrium unlike the 159 recruited from the general population. Our results suggest that ACE polymorphisms are associated with both the smoking history of an individual and their risk of developing COPD.

Diaphragm ultrasonography as an alternative to whole-body plethysmography in pulmonary function testing.

OBJECTIVE: Whole-body plethysmography is a common method of measuring pulmonary function. Although this technique provides a sensitive measure of pulmonary function, it can be problematic and unsuitable in some patients. The development of more accessible techniques would be beneficial. METHODS: A prospective study was performed to validate diaphragm ultrasonography as an alternative to whole-body plethysmography in patients referred for pulmonary function testing. Diaphragm movement and position were assessed by ultrasonography after standard pulmonary function testing using whole-body plethysmography. RESULTS: A wide range of lung function was observed. Standard lung volumes were as follows: total lung capacity, 5.57 +/- 1.31 L, residual volume, 2.27 +/- 0.56 L; and vital capacity, 3.30 +/- 0.98 L (mean +/- SD). The ratio of forced expiratory volume in 1 second to forced vital capacity was calculated as 0.69 +/- 0.08. Ultrasonography showed that mean diaphragm excursion values were 11.1 +/- 3.8 mm (2-dimensional), 14.7 +/- 4.1 mm during quiet breathing (M-mode), and 14.8 +/- 3.9 mm during a maximal sniff (M-mode). The velocity of diaphragm movement rose sharply during the sniff maneuver from 15.2 +/- 5.8 mm/s during quiet breathing to 104.0 +/- 33.4 mm/s. Static 2-dimensional measures of diaphragm position at the end of quiet inspiration or expiration correlated with standard measures of lung volume on plethysmography (eg, a correlation coefficient of 0.83 was obtained with end inspiration and vital capacity). All measures of diaphragm movement (whether by 2-dimensional or M-mode techniques) were poorly correlated with any lung volumes measured. CONCLUSIONS: These data suggest that dynamic measurements using diaphragm ultrasonography provide a relatively poor measure of pulmonary function in relation to whole-body plethysmography.

Altered oscillatory work by ventricular myofilaments from a rabbit coronary artery ligation model of heart failure.

OBJECTIVES: Understanding the changed ability of cardiac myofilaments to produce pump work requires knowledge of kinetics of crossbridge function as well as more widely studied parameters such as Ca-sensitivity and isometric force development. We tested the hypothesis that altered crossbridge kinetics contribute to reduced myofilament work in early-stage heart failure (left ventricular dysfunction, LVD). METHODS: The sinusoidal oscillation technique can yield insights into crossbridge function. Dynamic stiffness, oscillatory work and power were assessed in chemically skinned, Ca-activated trabeculae from rabbit ventricles in early-stage failure, 8 weeks after infarction induced by coronary artery ligation (LIG). Results were compared with sham-operated controls (SH). LVD was assessed by echocardiography. RESULTS: Ca-activated force and myofilament Ca-sensitivity were not significantly altered at this early stage of LVD. In maximally Ca-activated preparations, the frequency of minimal dynamic stiffness (f(min)) was 23% lower in LIG. f(min) increases by >80% between pCa 5.8 and 4 in SH but not in LIG. Maximal phase lead and lag angles (between length and tension) were lower in LIG at frequencies near f(min), lowering oscillatory work and power. The Lissajous figures (oscillatory work loops) of imposed length vs. tension are often asymmetric near f(min). The degree of asymmetry was greater in LIG. CONCLUSIONS: Reduced capacity for mechanical power, consistent with depressed haemodynamic performance in LVD hearts, is only partially attributable to crossbridge slowing; changes in the phase relationship will also contribute. These changes are not readily attributable to known alterations in contractile protein isoforms. Some deductions are drawn about which steps in the crossbridge cycle are modified in this model of LVD. Altered cardiac myocyte Ca-transients, reported to be associated with LVD, will be translated into pump work by a contractile machinery that is functionally altered, even though isometric force and myofilament Ca-sensitivity might remain near-normal at this stage.