Dietary Intake of Soccer Players before, during and after an Official Game: Influence of Competition Level and Playing Position.

Physical demands in soccer differ according to league level and playing position and may influence nutritional requirements. This study examined the effect of competition level and playing position on dietary intake in male soccer players (SP). Diet was weighed and recorded by 123 SP for 3 days; before, on the day, and the day after an official match. SP in the Super League (SL, n = 33) division reported higher (p < 0.05) average three-day energy (195 ± 36 kJ/kg), carbohydrate (6.0 ± 1.1 g/kg), and protein (2.2 ± 0.5 g/kg) intakes compared to the intakes reported by SP in the 2nd (n = 30) (energy: 159 ± 31 kJ/kg; carbohydrate: 4.6 ± 1.2 g/kg; protein: 1.9 ± 0.4 g/kg), 3rd (n = 30) (energy: 153 ± 34 kJ/kg; carbohydrate: 4.5 ± 1.2 g/kg; protein: 1.7 ± 0.4 g/kg), and 4th (n = 30) (energy: 152 ± 36 kJ/kg; carbohydrate: 4.2 ± 1.2 g/kg; protein: 1.7 ± 0.5 g/kg) national leagues (mean ± SD). Furthermore, when data were analyzed by playing position (pooled data), wide midfielders reported higher (p < 0.05) energy (183 ± 33 kJ/kg), carbohydrate (5.4 ± 1.2 g/kg), and fat (1.5 ± 0.4 g/kg) intakes compared to central defenders (energy: 147 ± 37 kJ/kg; carbohydrate: 4.1 ± 1.1 g/kg; fat: 1.2 ± 0.4 g/kg). The dietary intake of SP may differ according to the playing position and competition level, possibly due to different metabolic demands in training and competition.

Mitochondrial Dysfunction and Sarcopenic Obesity: The Role of Exercise.

Sarcopenic obesity (SO) constitutes the coexistence of skeletal muscle mass loss (sarcopenia) and excess adiposity (obesity). It is mainly considered as a condition in the elderly with health-threatening impacts ranging from frailty to mortality. Mitochondrial dysfunction consists one of the basic pathophysiological mechanisms leading to the development of SO and its consequences. Indirect indicators of mitochondrial function, such as VO2max and exercise capacity, have been demonstrated to be negatively affected in individuals with SO, while the positive effect of exercise on mitochondrial function has been widely proved; thus, in this review, we aimed at investigating the effects of endurance, resistance, and concurrent exercise training on indexes of mitochondrial dysfunction in SO patients. The results of the clinical trials evaluated reveal positive effects of chronic exercise on VO2max and physical capacity, as well as mitochondrial biogenesis and activity. It has been concluded that utilizing a systematic exercise training program that includes both aerobic and strength exercises can be an effective strategy for managing SO and promoting overall health in these patients.

Young Artistic Gymnasts Drink Ad Libitum Only Half of Their Fluid Lost during Training, but More Fluid Intake Does Not Influence Performance.

To examine the effect of the fluid balance on and performance in young artistic gymnasts during training under ad libitum and prescribed fluid intake conditions, eleven males (12.3 ± 2.6 years, mean ± SD) performed two 3 h identical training sessions. Participants ingested, in a random order, water equivalent to either 50% (LV) or 150% (HV) of their fluid loss. After the 3 h training, the gymnasts performed program routines on three apparatuses. The pre-exercise urine specific gravity (USG) was similar between conditions (LV: 1.018 ± 0.007 vs. HV: 1.015 ± 0.007; p = 0.09), while the post-exercise USG was lower in the HV condition (LV: 1.017 ± 0.006 vs. HV: 1.002 ± 0.003; p < 0.001). Fluid loss corresponding to percentage of body mass was higher in the LV condition (1.2 ± 0.5%) compared to the HV condition (0.4 ± 0.8%) (p = 0.02); however, the sums of the score performances were not different (LV: 26.17 ± 2.04 vs. HV: 26.05 ± 2.00; p = 0.57). Ingesting fluid equivalent to about 50% of the fluid lost, which was the amount that was drunk ad libitum during training, maintained short-term hydration levels and avoided excessive dehydration in artistic preadolescent and adolescent gymnasts. A higher amount of fluid, equivalent to about 1.5 times the fluid loss, did not provide an additional performance benefit.

Effects of Resistance and Endurance Training Alone or Combined on Hormonal Adaptations and Cytokines in Healthy Children and Adolescents: A Systematic Review and Meta-analysis.

BACKGROUND: No previous systematic review has quantitatively compared the effects of resistance training, endurance training, or concurrent training on hormonal adaptations in children and adolescents. Objective was to examine the effects of exercise training and training type on hormonal adaptations in children and adolescents. METHODS: A systematic literature search was conducted in the following databases: PubMed, Web of Science, and EBSCO. Eligibility criteria were: population: healthy youth population sample (mean age < 18 years); intervention: resistance training, endurance training, or concurrent training (> 4 weeks duration); comparison: control group; outcome: pre- and post-levels of hormones and cytokines; and study design: randomized and non-randomized controlled trials. We used a random-effect model for the meta-analysis. The raw mean difference in hormones from baseline to post-intervention was presented alongside 95% confidence intervals (CI). Further, the certainty of evidence quality and the risk of bias were assessed. RESULTS: A total of 3689 records were identified, of which 14 studies were eligible for inclusion. Most studies examined adolescents with fewer studies on children (age < 12 years, N = 5 studies) and females (N = 2 studies). Nine exercise training programs used endurance training, five studies used resistance training, and no eligible study used concurrent training. The meta-analysis showed no significant effect of exercise training on testosterone (MD = 0.84 nmol/L), cortisol (MD = - 17.4 nmol/L), or SHBG (MD = - 5.58 nmol/L). Subgroup analysis showed that resistance training significantly increased testosterone levels after training (MD = 3.42 nmol/L) which was not observed after endurance training (MD = - 0.01 nmol/L). No other outcome differed between training types. Exercise training resulted in small and non-significant changes in GH (MD = 0.48 ng/mL, p = 0.06) and IGF-I (MD = - 22.90 ng/mL, p = 0.07). GH response to endurance training may be age-dependent and evident in adolescents (MD = 0.59 ng/mL, p = 0.04) but not when children and adolescents are pooled (MD = 0.48 ng/mL, p = 0.06). Limited evidence exists to conclude on IL-6 and TNF-α effects of exercise training. Assessments of GRADE domains (risk of bias, consistency, directness, or precision of the findings) revealed serious weaknesses with most of the included outcomes (hormones and cytokines). CONCLUSIONS: This systematic review suggests that exercise training has small effects on hormonal concentrations in children and adolescents. Changes in testosterone concentrations with training are evident after resistance training but not endurance training. GH's response to training may be affected by maturation and evident in adolescents but not children. Further high-quality, robust training studies on the effect of resistance training, endurance training, and concurrent training are warranted to compare their training-specific effects. REGISTRATION: PROSPERO: CRD42021241130.

Oxygen Uptake in Repeated Cycling Sprints Against Different Loads Is Comparable Between Men and Preadolescent Boys.

Children recover faster than adults in repeated sprints, but it is unclear if their aerobic responses differ. Purpose: This study tested the hypothesis that aerobic response (VO2) during repeated sprints is greater in preadolescent boys than in men. Further, this study compared normalization with conventional ratio-scaling and scaling with the use of body mass (BM) as a covariate. Methods: Nine boys (age: 11.8 ± 0.6 years, swimmers) and 11 men (age: 21.7 ± 0.6 years, recreational athletes) performed 10 maximal 6-s cycling sprints separated by 24-s of passive recovery, against two loads (optimum and 50% of optimum). Oxygen uptake (VO2) was measured continuously. Results: Men's mean power output (MPO) was greater than boys in each sprint, both in absolute (unscaled) values ( p < 0.05) and when adjusted for lean leg volume ( p < 0.05). Children had lower absolute VO2 ( p < 0.05) than men, but when it was adjusted for BM or power-output, VO2 was comparable between men and boys. Thus, most of the difference in VO2 between men and boys was due to body size and power-output differences. Conclusion: Our results suggest that men and boys have similar VO2 during repeated sprints when appropriately adjusted to body mass or power output. Results highlight the importance of using appropriate scaling methods to compare adults' and children's aerobic responses to high-intensity exercise.

Effects of Core Strength Training on Skiing Economy in Elite Junior Cross-Country Skiers.

Purpose: In cross-country (XC) skiing, the ability to use an efficient technique is essential for performance. The study aimed to compare the effects of supplemental static or dynamic core strength training on skiing economy in elite junior XC skiers. Methods: Twenty-four elite junior XC skiers (14 women, 10 men; 17.8 ± 1.1 years; 67.8 ± 10.0 kg, 173.7 ± 6.4 cm) participated in this study. Participants were allocated either to a static core training (ST) group (n =12) or to a dynamic core training (DT) group (n = 12). Both groups continued their normal aerobic endurance and muscular strength training. Experimental groups performed a 15 minutes, 3 days/week core strength-training program for 9 weeks and in addition to their training. Submaximal and maximal roller ski testing was conducted before and after the 9-week training period. Results: Results showed no significant interaction between groups for energetic costs in any of the submaximal workloads (first, p = .33; second, p =.79; third, p = .25). Pooled data showed a significant improvement in energetic cost pre- to posttesting in the first and third workload (ES 0.40, p = .0006 and ES 0.42, p = .04 respectively). Nine weeks of static or dynamic core strength training in elite junior XC skiers had a small effect on energetic cost in submaximal roller skiing. Conclusion: The type of supplemental core strength training does not seem to affect economy in submaximal roller skiing.

Effects of Different Types of Lower Body Resistance Exercise on Upper-body Strength in Men and Women, with Special Reference to Anabolic Hormones.

Resistance exercise has been shown to induce an acute hormonal response. The purpose of this study was to examine upper-body adaptations and the endocrine response to strength training in men and women when subjected to two different types of lower-body resistance training protocols. Nine males and eight females were assigned to either a Heavy Load (HL) (N = 10) or Mixed Load (ML) (N = 7) training routine three times per week for ten weeks. The HL-group executed low-volume, high-load resistance exercise for both lower and upper-body (4-6 reps at 80-90% of one repetition maximum (1-RM), three-minute inter-set rest). The ML-group performed the HL-protocol for the upper-body, but a high-volume, moderate-load protocol for the lower body (10-15 reps at 60-70% of 1-RM, one-minute inter-set rest). Volume load, 1-RM strength and hormonal measurements were analyzed by repeated-measures linear mixed models. Both groups increased their 1-RM in all assessments (p < 0.01) with no significant difference between groups at any time. Growth hormone (GH), testosterone and bioavailable testosterone (T/SHBG) increased in both groups during a standardized exercise session (p < 0.01) with ML having a greater increase in GH. The notion that acute elevations in anabolic hormones is important for muscle strength adaptation cannot be supported by the present study.

Lack of Predictive Power in Commonly Used Tests for Performance in Alpine Skiing.

Competitive alpine skiing is a complex sport that requires high physical and technical competence. Testing the physical status of athletes may be important to increase their ability to achieve elite sport-specific performance. This study aimed to investigate the predictive power of the national test battery of the Swedish Olympic Committee (Fysprofilen) and anthropometric variables in the prediction of competitive performance of elite alpine skiers, indicated by Fédération Internationale de Ski points. Data from fourteen Swedish elite female alpine skiers were analyzed using bivariate and multivariate statistical methods. Physiological test results and anthropometric data could not generate significant bivariate or multivariate models for prediction of competitive performance. Multivariate regression (R2) and prediction (Q2) models for Fédération Internationale de Ski Slalom and Giant Slalom rank reached R2=0.27 to 0.43, Q2=+- 0.8 to-0.17, indicating no valid models. The overall interpretation of these and previous findings are that future test batteries must be validated before implemented, and that test results should be treated with caution when it comes to prediction of future competitive results. Applying tests that are not validated against competitive performance risk misleading coaches and training advisors who aim to increase the sports-specific performance of the individual athlete.

Expression of tissue remodelling, inflammation- and angiogenesis-related factors after eccentric exercise in humans.

Eccentric exercise has been extensively used as a model to study the contraction-induced muscle damage and its consequent processes. This study aimed at examining molecular responses associated with tissue remodelling, inflammation and angiogenesis in skeletal muscle during the recovery period after eccentric exercise in humans. Ten healthy men performed 50 maximal eccentric muscle actions with the knee extensors and muscle biopsies were collected from the vastus lateralis before and 6 h, 48 h and 120 h post eccentric exercise. Real Time-PCR was utilized to investigate alterations in gene expression of various tissue remodelling-, inflammation- and angiogenesis-related factors: uPA, uPA-R, TGF-ß1, MMP-9, TNF-α, IL-6, IL-8, VEGF, VEGFR-2, HIF-1a, Ang-1, Ang-2 and Tie-2. The uPA/uPA-R system exhibited a similar time-expression pattern increasing 6 h post exercise (p < 0.05), while the other tissue remodelling factors TGF-ß1 and MMP-9 did not change significantly over time. Transcriptional responses of inflammatory factors TNF-α and IL-8 increased significantly and peaked 6 h post eccentric exercise (p < 0.05), while IL-6 exhibited a similar, though not statistically significant, expression profile (p > 0.05). Similarly, the expression of angiopoietin receptor Tie-2 showed an early increase only at 6 h after the completion of exercise (p < 0.05), while the other angiogenic factors failed to reach statistical significance due a high interindividual variability in the gene expression responses. The early transcriptional upregulation of tissue remodelling, inflammation- and angiogenesis-related factors post eccentric exercise may indicate the acute intramuscular activation of these processes functionally related to muscle damage-induced adaptation.

Aerobic Variables for Prediction of Alpine Skiing Performance - A Novel Approach.

The aim of this study was to investigate the predictive power of aerobic test results and anthropometric variables on FIS-ranking of junior elite alpine skiers. Results from twenty-three male and female adolescent elite alpine skiers from two seasons were included in the multivariate statistical models. Physical work capacity was determined by V̇O2peak, blood lactate concentration ([HLa]b), and heart rate (HR) during ergometer cycling. Anthropometric variables were body stature, body weight and calculated BMI. No significant correlation between competitive performance and aerobic work capacity or anthropometric data was observed neither in male nor female adolescent skiers. Pre-season physical tests and anthropometric data could therefore not predict end-season FIS-ranking. The best regression (R2) and prediction (Q2) models of FIS slalom (SL) and giant slalom (GS) rank reached R2=0.51 to 0.86, Q2=-0.73 to 0.18, indicating no valid models. This study could not establish V̇O2peak and other included variables as predictors of competitive performance. When combining results from commonly used tests for alpine skiers, and applying multivariate statistical models, investigated tests seems of limited used for athletes, coaches, and ski federations. Performance-specific pre-season tests must be developed and validated for prediction of performance and guidance of exercise training.

Cytokines in muscle damage.

Multiple cellular and molecular processes are rapidly activated following skeletal muscle damage to restore normal muscle structure and function. These processes typically involve an inflammatory response and potentially the consequent occurrence of secondary damage before their resolution and the completion of muscle repair or regeneration. The overall outcome of the inflammatory process is potentially divergent, with the induction of prolonged inflammation and further muscle damage, or its active termination and the promotion of muscle repair and regeneration. The final, detrimental, or beneficial effect of the inflammatory response on muscle repair is influenced by specific interactions between inflammatory and muscle cell-derived cytokines that act as positive and/or negative regulators to coordinate local and systemic inflammatory-related events and modulate muscle repair process. A crucial balance between proinflammatory and anti-inflammatory cytokines appears to attenuate an excessive inflammatory reaction, prevent the development of muscle fibrosis, and adequately promote the regenerative process. In this review, we address the interactive cytokine responses following muscle damage, in the context of induction and progression, or resolution of muscle inflammation and the promotion of muscle repair.

Subdivision of molecularly-classified groups by new gene signatures in breast cancer patients.

Gene expression patterns as well as gene interactions are under investigation for their involvement in tumour heterogeneity. The molecular classification of breast cancer based on hormone receptor expression, grade and HER2 receptor levels, is indicative but not adequate enough to complete the prognostic data. The objectives of this study were to validate the prognostic value of 19 genes, solely, and as parts of classifiers (sets of genes), in breast cancer patients and to determine whether the expression of these genes and classifiers is correlated with breast cancer molecular classification. Gene expression was examined in the blood of 88 breast cancer patients and 50 healthy controls using multiplex quantitative real-time PCR. Patients with a second primary malignancy showed a statistically significant difference when compared with: i) patients with a single breast cancer, for an 8-gene classifier (p<0.02); and ii) healthy individuals (classifier FBX033, FLJ339115) (p<0.01), with respect to gene expression. The classifier ENY2, USP38 was associated with the development of primary breast cancer. A newly established classifier (ENY2, USP38, RPS7, Osbpl-1 and ETF1) indicated a statistically significant association with HER2 subtype patients, compared to patients with a different molecular classification (p<0.04). The gene FLJ33915 was differentially expressed in a subgroup of HER2-positive patients with infiltrated axillary lymph nodes (p<0.028). We validated the prognostic value of 4 classifiers for primary and second primary malignancy. Evidence of a classifier predicting the HER2 subtype and the gene FLJ33915 which subdivides HER2 subtype patients is also presented.

IGF1Ec expression in MG-63 human osteoblast-like osteosarcoma cells.

AIM: The insulin-like growth factor 1 (IGF1) gene gives rise to multiple transcripts, using an elaborate alternative splicing mechanism. The aim of this study was to shed light on the expression and role of the IGF1 system in human MG-63 osteoblast-like osteosarcoma cells. MATERIALS AND METHODS: The expression of the IGF1Ea, IGF1Eb and IGF1Ec isoforms was characterized using reverse transcription polymerase chain reaction (RT-PCR), quantitative real time-PCR (qRT-PCR) and western blot analysis. Using trypan blue exclusion assays, we also examined the mitogenic effects of IGF1 and of a synthetic peptide related to the E domain of IGF1Ec (synthetic E peptide) on MG-63 cells, as well as on MG-63 cells which had been molecularly modified to restrain the expression of type I IGF receptor (IGF1R) and of insulin receptor (INSR) by siRNA techniques (IGF1R KO or INSR KO MG-63 cells). RESULTS: MG-63 cells express only the IGF1Ea and IGF1Ec transcripts. Exogenous administration of dihydrotestosterone (DHT) significantly increased the expression of IGF1Ea and IGF1Ec mRNA and it induced the previously undetectable expression of IGF1Eb transcript. Exogenous administration of IGF1, insulin and the synthetic E peptide stimulated the growth of MG-63 cells, while only E peptide stimulated the growth of IGF1R KO and INSR KO MG-63 cells. CONCLUSION: These data suggest that the expression of all IGF1 isoforms is hormonally regulated in MG-63 cells and that the expression of IGF1Ec may be involved in osteosarcoma biology by generating the Ec peptide which acts via an IGF1R-independent and INSR-independent mechanism.

Effects of two different half-squat training programs on fatigue during repeated cycling sprints in soccer players.

This study compared the effects of two different half-squat training programs on the repeated-sprint ability of soccer players during the preseason. Twenty male professional soccer players were divided into 2 groups: One group (S-group) performed 4 sets of 5 repetitions with 90% of their 1-repetition maximum (1RM), and the other group (H-group) performed 4 sets of 12 repetitions with 70% of 1RM, 3 times per week for 6 weeks, in addition to their common preseason training program. Repeated-sprint ability was assessed before and after training by 10 × 6-second cycle ergometer sprints separated by 24 seconds of passive recovery. Maximal half-squat strength increased significantly in both groups (p < 0.01), but this increase was significantly greater in the S-group compared with the H-group (17.3 ± 1.9 vs. 11.0 ± 1.9%, p < 0.05). Lean leg volume (LLV) increased only in the H-group. Total work over the 10 sprints improved in both groups after training, but this increase was significantly greater in the second half (8.9 ± 2.6%) compared with the first half of the sprint test (3.2 ± 1.7%) only in the S-group. Mean power output (MPO) expressed per liter of LLV was better maintained during the last 6 sprints posttraining only in the S-group, whereas there was no change in MPO per LLV in the H-group over the 10 sprints. These results suggest that resistance training with high loads is superior to a moderate-load program, because it increases strength without a change in muscle mass and also results in a greater improvement in repeated sprint ability. Therefore, resistance training with high loads may be preferable when the aim is to improve maximal strength and fatigue during sprinting in professional soccer players.

Influence of resistive load on power output and fatigue during intermittent sprint cycling exercise in children.

This study examined the effects of two resistive loads on fatigue during repeated sprints in children. Twelve 11.8 (0.2) year old boys performed a force-velocity test to determine the load (Fopt) corresponding to the optimal pedal rate. On two separate occasions, ten 6-s sprints interspersed with 24-s recovery intervals were performed on a friction-loaded cycle ergometer, against a load equal to Fopt or 50%Fopt. Although mean power output (MPO) was higher in the Fopt [397 (24) and 356 (19) W, P < 0.01], the decline in MPO over the 10 sprints was similar in Fopt [8.8 (1.9) %] and 50%Fopt [9.0 (2.4) %]. In contrast, peak power (PPO) was not different in sprint 1 between the two conditions [459 (24) and 460 (28) W], but was decreased only in 50%Fopt [11.4 (3.2) %, P < 0.01], while it was maintained in the Fopt despite the higher total work during each sprint. Fatigue within each sprint (percent drop from peak to end power output) was also higher in the 50%Fopt compared with the Fopt [32 (2.5) vs. 10 (1.6) %, P < 0.01]. Peak and mean pedal rate in Fopt condition were close to the optimum (Vopt), while a large part of the sprint time in 50%Fopt was spent far from Vopt. The present study shows that sprinting against Fopt reduces fatigue within and between repeated short sprints in children. It is suggested that fatigue during repeated sprints is modified when pedal rate is not close to Vopt, according to the parabolic power versus pedal rate relationship.