Poor Reliability of Measurement Instruments to Assess Acute Responses to Load in Soccer Players Irrespective of Biological Maturity Status.

PURPOSE: To assess the short-term reliability of measurement instruments to quantify the acute psychophysiological response to load in adolescent soccer players in relation to biological maturity. METHODS: Data were collected from 108 U12 to U17 soccer players on 2 consecutive weeks (pre, n = 32; at, n = 34; and post, n = 42 estimated peak height velocity). Measurements consisted of the Short Recovery and Stress Scale, a countermovement jump, assessment of leg stiffness, and a submaximal run to assess exercise heart rate and heart rate recovery. Test-retest reliability was assessed with the coefficient of variation (CV) and intraclass correlation coefficient (ICC). RESULTS: Items of the Short Recovery and Stress Scale showed poor reliability across maturity groups (CV = 7.0%-53.5%; ICC = .28 to .79). Only few countermovement jump variables (jump height, concentric impulse, and concentric velocity) possessed good reliability. For most variables of the countermovement jump, reliability was better for the post peak height velocity group followed by at-peak height velocity and prepeak height velocity. Very high levels of reliability across maturity groups were observed for exercise heart rate (CV < 1.8%; ICC > .94), while heart rate recovery was more variable (CV < 16.5%; ICC > .48). CONCLUSION: Results suggest that the majority of investigated variables have poor reliability, questioning their ability to detect small, yet meaningful changes in acute responses to load in adolescent soccer players.

The glucocorticoid-induced leucine zipper mediates statin-induced muscle damage.

Statins, the most prescribed class of drugs for the treatment of hypercholesterolemia, can cause muscle-related adverse effects. It has been shown that the glucocorticoid-induced leucine zipper (GILZ) plays a key role in the anti-myogenic action of dexamethasone. In the present study, we aimed to evaluate the role of GILZ in statin-induced myopathy. Statins induced GILZ expression in C2C12 cells, primary murine myoblasts/myotubes, primary human myoblasts, and in vivo in zebrafish embryos and human quadriceps femoris muscle. Gilz induction was mediated by FOXO3 activation and binding to the Gilz promoter, and could be reversed by the addition of geranylgeranyl, but not farnesyl, pyrophosphate. Atorvastatin decreased Akt phosphorylation and increased cleaved caspase-3 levels in myoblasts. This effect was reversed in myoblasts from GILZ knockout mice. Similarly, myofibers isolated from knockout animals were more resistant toward statin-induced cell death than their wild-type counterparts. Statins also impaired myoblast differentiation, and this effect was accompanied by GILZ induction. The in vivo relevance of our findings was supported by the observation that gilz overexpression in zebrafish embryos led to impaired embryonic muscle development. Taken together, our data point toward GILZ as an essential mediator of the molecular mechanisms leading to statin-induced muscle damage.

Construct validity of age at predicted adult height and BAUS skeletal age to assess biological maturity in academy soccer.

BACKGROUND: The assessment of biological maturity status plays an important role in talent identification and development programs. AIM: To compare age at predicted adult height and BAUS skeletal age as indicators of biological maturity status in youth soccer players using a construct-validity approach. SUBJECTS AND METHODS: Participants were 114 players from the U12 to U17 age groups of a professional youth soccer academy. Maturity status was determined via percentage of predicted adult height based upon the Khamis-Roche method (somatic maturity) and assessed via the SonicBone BAUSTM system (skeletal maturity). Convergent and known-groups validity were evaluated between maturity assessment methods and by comparing maturity-related selection biases across age groups. RESULTS: Although maturity status indicators were largely interrelated (r = .94, 95%CL 0.91-0.96), concordance (κ = 0.31 to 0.39) and Spearman's rank-order correlations (ρ = 0.45-0.52) of classification methods were moderate. A selection bias towards early maturing players emerged in the U14 age group which remained relatively consistent through to the U17 age group. CONCLUSIONS: Results confirm the construct-validity of both methods to assess biological maturity status although further validation relative to established indicators of biological maturity is needed. Furthermore, caution is also warranted when interpreting maturity status classification methods interchangeably given the poor concordance between classification methods.

Differential effects of endurance, interval, and resistance training on telomerase activity and telomere length in a randomized, controlled study.

Aims: It is unknown whether different training modalities exert differential cellular effects. Telomeres and telomere-associated proteins play a major role in cellular aging with implications for global health. This prospective training study examines the effects of endurance training, interval training (IT), and resistance training (RT) on telomerase activity and telomere length (TL). Methods and results: One hundred and twenty-four healthy previously inactive individuals completed the 6 months study. Participants were randomized to three different interventions or the control condition (no change in lifestyle): aerobic endurance training (AET, continuous running), high-intensive IT (4 × 4 method), or RT (circle training on 8 devices), each intervention consisting of three 45 min training sessions per week. Maximum oxygen uptake (VO2max) was increased by all three training modalities. Telomerase activity in blood mononuclear cells was up-regulated by two- to three-fold in both endurance exercise groups (AET, IT), but not with RT. In parallel, lymphocyte, granulocyte, and leucocyte TL increased in the endurance-trained groups but not in the RT group. Magnet-activated cell sorting with telomerase repeat-ampliflication protocol (MACS-TRAP) assays revealed that a single bout of endurance training-but not RT-acutely increased telomerase activity in CD14+ and in CD34+ leucocytes. Conclusion: This randomized controlled trial shows that endurance training, IT, and RT protocols induce specific cellular pathways in circulating leucocytes. Endurance training and IT, but not RT, increased telomerase activity and TL which are important for cellular senescence, regenerative capacity, and thus, healthy aging.

Spring is in the air: seasonal profiles indicate vernal change of miRNA activity.

The envisioned application of miRNAs as diagnostic or prognostic biomarkers calls for an in-depth understanding of their distribution and variability in different physiological states. While effects with respect to ethnic origin, age, or gender are known, the inter-individual variability of miRNAs across the four seasons remained largely hidden. We sequentially profiled the complete repertoire of blood-borne miRNAs for 25 physiologically normal individuals in spring, summer, fall, and winter (altogether 95 samples) and validated the results on 292 individuals (919 samples collected with the Mitra home sampling device) by RT-qPCR. Principal variance component analysis suggests that the largest variability observed in miRNA expression is due to individual variability and the individuals' gender. But the results also highlight a deviation of miRNA activity in samples collected during spring time. Following adjustment for multiple testing, remarkable differences are observed between spring and fall (77 miRNAs). The two most dys-regulated miRNAs were miR-181c-5p and miR-106b-5p (adjusted p-value of 0.007). Other significant miRNAs include miR-140-3p, miR-21-3p, and let-7c-5p. The dys-regulation was validated by RT-qPCR. Systems biology analysis further provides strong evidence for the immunological origin of the signals: dys-regulated miRNAs are enriched in CD56 cells and belong to various signalling and immune-system-related pathways. Our data suggest that besides known confounding factors such as age and sex, also the season in which a test is conducted might have a considerable influence on the expression of blood-borne miRNAs and subsequently might interfere with diagnosis based on such signatures.

Postexercise Hypotension as a Predictor for Long-Term Training-Induced Blood Pressure Reduction: A Large-Scale Randomized Controlled Trial.

OBJECTIVE: To investigate the correlation between acute exercise effects and chronic training effects on blood pressure (BP). DESIGN: Randomized, controlled training study focusing on the optimization of preventive effects of physical training. SETTING: The study was performed in a university department. PARTICIPANTS: One hundred twenty-seven healthy, untrained subjects. INTERVENTION: Subjects were divided into 4 groups: interval endurance training (IET) (n = 26, 4 × 4 min at 95% maximal heart rate), continuous endurance training (CET) (n = 23, 45 minutes at 60% heart rate reserve), strength endurance training (SET) (n = 40, 8 machine-based exercises, each 2 x 15 repetitions at the 20 repetition maximum), and control (CON) (n = 38). In the 3 training groups, subjects trained 3 times a week for 6 months, the CON group was asked to retain their sedentary lifestyle. MAIN OUTCOME MEASURES: The acute exercise effect on BP was defined as the change of BP after an exhaustive stage test, compared with baseline. The chronic training effect on BP was determined as the change of resting BP after the 6-month training period. RESULTS: For CET, a significant correlation between acute and chronic effects on systolic (r = 0.66, P = 0.001) and diastolic (r = 0.66, P = 0.001) BP was observed. For SET, a significant correlation (r = 0.45, P = 0.007) was found only for diastolic BP. No significant correlations were found for IET. CONCLUSIONS: It can be assumed that postexercise hypotension is an easy-to-use predictor for the efficacy of CET to reduce BP, and may be a valuable tool for physicians to individualize prescribed training schedules for patients to reduce cardiovascular risk. TRIAL REGISTRATION: www.clinicaltrials.gov; ID: NCT01263522.

Carbohydrate intake and training efficacy - a randomized cross-over study.

Carbohydrate (CHO) availability during endurance exercise seems to attenuate exercise-induced perturbations of cellular homeostasis and might consequently diminish the stimulus for training adaptation. Therefore, a negative effect of CHO intake on endurance training efficacy seems plausible. This study aimed to test the influence of carbohydrate intake on the efficacy of an endurance training program on previously untrained healthy adults. A randomized cross-over trial (8-week wash-out period) was conducted in 23 men and women with two 8-week training periods (with vs. without intake of 50g glucose before each training bout). Training intervention consisted of 4x45 min running/walking sessions/week at 70% of heart rate reserve. Exhaustive, ramp-shaped exercise tests with gas exchange measurements were conducted before and after each training period. Outcome measures were maximum oxygen uptake (VO2max) and ventilatory anaerobic threshold (VT). VO2max and VT increased after training regardless of CHO intake (VO2max: Non-CHO 2.6 ± 3.0 ml*min-1*kg-1 p = 0.004; CHO 1.4 ± 2.5 ml*min-1*kg-1 p = 0.049; VT: Non-CHO 4.2 ± 4.2 ml*min-1*kg-1 p < 0.001; CHO 3.0 ± 4.2 ml*min-1*kg-1 p = 0.003). The 95% confidence interval (CI) for the difference between conditions was between +0.1 and +2.1 ml*min-1*kg-1 for VO2max and between -1.2 and +3.1 for VT. It is concluded that carbohydrate intake could potentially impair the efficacy of an endurance training program.

Impact of a Short-Term Water Abstinence on Airway Hyperresponsiveness in Elite Swimmers.

OBJECTIVE: To investigate the effect of a swimming break on airway hyperresponsiveness (AHR) and to evaluate perception of bronchoconstriction-related symptoms after methacholine challenge testing (MCT). DESIGN: Observational, controlled study. SETTING: University department. PARTICIPANTS: Overall, 25 healthy, elite, competitive swimmers aged ≥14 years from the local Olympic training center and 25 healthy control subjects. INDEPENDENT VARIABLE: Duration of water abstinence. MAIN OUTCOME MEASURES: Primary outcome measures were a positive MCT with a provocation dose (PD) and the perception score of bronchoconstriction-related symptoms at visit 1 (V1, training period) and visit 2 (V2, after swimming break). RESULTS: In the study, 13 swimmers (52%) and 10 control subjects (40%) showed AHR. The PD did not differ significantly between V1 and V2 in the swimmers (P = 0.81) or in the control subjects (P = 0.74). No correlation of fraction of exhaled nitric oxide with the PD could be established in both the groups (swimmers: P = 0.97; controls: P = 0.99). The majority of swimmers with AHR were asymptomatic, and only minimal differences in perception of bronchoconstriction-related symptoms between swimmers and control subjects were observed (P = 0.23). CONCLUSIONS: A swimming break of 25 ± 8 days does not seem sufficient to significantly reduce AHR in elite swimmers. Thus, relevant and systematic effects of short-term water abstinence on AHR seem unlikely. Because the majority of swimmers remain asymptomatic, AHR may escape routine screening examinations. The impact of AHR on athletic performance and the long-term clinical consequences remain to be clarified.

Individual Patterns in Blood-Borne Indicators of Fatigue-Trait or Chance.

Julian, R, Meyer, T, Fullagar, HHK, Skorski, S, Pfeiffer, M, Kellmann, M, Ferrauti, A, and Hecksteden, A. Individual patterns in blood-borne indicators of fatigue-trait or chance. J Strength Cond Res 31(3): 608-619, 2017-Blood-borne markers of fatigue such as creatine kinase (CK) and urea (U) are widely used to fine-tune training recommendations. However, predictive accuracy is low. A possible explanation for this dissatisfactory characteristic is the propensity of athletes to react to different patterns of fatigue indicators (e.g., predominantly muscular [CK] or metabolic [U]). The aim of the present trial was to explore this hypothesis by using repetitive fatigue-recovery cycles. A total of 22 elite junior swimmers and triathletes (18 ± 3 years) were monitored for 9 weeks throughout 2 training phases (low-intensity, high-volume [LIHV] and high-intensity, low-volume [HILV] phases). Blood samples were collected each Monday (recovered) and Friday (fatigued) morning. From measured values of CK, U, free-testosterone (FT), and cortisol (C) as determined in the rested and fatigued state, respectively, Monday-Friday differences (Δ) were calculated and classified by magnitude before calculation of ratios (ΔCK/ΔU and ΔFT/ΔC). Coefficient of variation (CV) was calculated as group-based estimates of reproducibility. Linear mixed modeling was used to differentiate inter- and intraindividual variability. Consistency of patterns was analyzed by comparing with threshold values (<0.9 or >1.1 for all weeks). Reproducibility was very low for fatigue-induced changes (CV ≥ 100%) with interindividual variation accounting for 45-60% of overall variability. Case-wise analysis indicated consistent ΔCK/ΔU patterns for 7 individuals in LIHV and 7 in HILV; 5 responded consistently throughout. For ΔFT/ΔC the number of consistent patterns was 2 in LIHV and 3 in HILV. These findings highlight the potential value of an individualized and multivariate approach in the assessment of fatigue.

miRNAs and sports: tracking training status and potentially confounding diagnoses.

BACKGROUND: The dependency of miRNA abundance from physiological processes such as exercises remains partially understood. We set out to analyze the effect of physical exercises on miRNA profiles in blood and plasma of endurance and strength athletes in a systematic manner and correlated differentially abundant miRNAs in athletes to disease miRNAs biomarkers towards a better understanding of how physical exercise may confound disease diagnosis by miRNAs. METHODS: We profiled blood and plasma of 29 athletes before and after exercise. With four samples analyzed for each individual we analyzed 116 full miRNomes. The study set-up enabled paired analyses of individuals. Affected miRNAs were investigated for known disease associations using network analysis. RESULTS: MiRNA patterns in blood and plasma of endurance and strength athletes vary significantly with differences in blood outreaching variations in plasma. We found only moderate differences between the miRNA levels before training and the RNA levels after training as compared to the more obvious variations found between strength athletes and endurance athletes. We observed significant variations in the abundance of miR-140-3p that is a known circulating disease markers (raw and adjusted p value of 5 × 10(-12) and 4 × 10(-7)). Similarly, the levels of miR-140-5p and miR-650, both of which have been reported as makers for a wide range of human pathologies significantly depend on the training mode. Among the most affected disease categories we found acute myocardial infarction. MiRNAs, which are up-regulated in endurance athletes inhibit VEGFA as shown by systems biology analysis of experimentally validated target genes. CONCLUSION: We provide evidence that the mode and the extent of training are important confounding factors for a miRNA based disease diagnosis.

Validity of Lactate Thresholds in Inline Speed Skating.

Lactate thresholds are commonly used as estimates of the highest workload where lactate production and elimination are in equilibrium (maximum lactate steady state [MLSS]). However, because of the high static load on propulsive muscles, lactate kinetics in inline speed skating may differ significantly from other endurance exercise modes. Therefore, the discipline-specific validity of lactate thresholds has to be verified. Sixteen competitive inline-speed skaters (age: 30 ± 10 years; training per week: 10 ± 4 hours) completed an exhaustive stepwise incremental exercise test (start 24 km·h, step duration 3 minutes, increment 2 km·h) to determine individual anaerobic threshold (IAT) and the workload corresponding to a blood lactate concentration of 4 mmol·L (LT4) and 2-5 continuous load tests of (up to) 30 minutes to determine MLSS. The IAT and LT4 correlated significantly with MLSS, and the mean differences were almost negligible (MLSS 29.5 ± 2.5 km·h; IAT 29.2 ± 2.0 km·h; LT4 29.6 ± 2.3 km·h; p > 0.1 for all differences). However, the variability of differences was considerable resulting in 95% limits of agreement in the upper range of values known from other endurance disciplines (2.6 km·h [8.8%] for IAT and 3.1 km·h [10.3%] for LT4). Consequently, IAT and LT4 may be considered as valid estimates of the MLSS in inline speed skating, but verification by means of a constant load test should be considered in cases of doubt or when optimal accuracy is needed (e.g., in elite athletes or scientific studies).

Passive heat therapy: a promising preventive measure for people at risk of adverse health outcomes during heat extremes.

The world is experiencing increased frequency, duration, and severity of life-threatening heat extremes. Most hospitalizations and excess deaths during extreme heat events are associated with preexisting diseases in older adults. As climate change persists, the global population ages and the number of individuals with chronic diseases expands, more people are at risk of adverse health outcomes during extreme heat events. Therefore, proactive preventive measures are urgently needed to mitigate heat-related health risks within these populations. In this context, passive heat therapy (e.g., hot baths, saunas, and water-perfused suits) emerges as a promising countermeasure to improve physiological resilience to a warming planet. Passive heating improves cardiovascular function and overall health in older adults and individuals living with chronic diseases, offering the prospect of reducing cardiovascular strain during hotter days. Moreover, some studies suggest that passive heat therapy can be an effective strategy for heat acclimation (i.e., improved thermoregulation). This review describes the existing literature on the effects of passive heat therapy on cardiovascular and thermoregulatory responses in individuals with higher heat-related health risks and explores the use of passive heating as a strategy for heat acclimation to mitigate health risks during extreme heat events.NEW & NOTEWORTHY Passive heat therapy improves cardiovascular function and health in middle-aged and older adults living with or without chronic diseases. In addition, preliminary studies indicate that passive heat interventions can induce heat acclimation, improving thermoregulatory responses. Thus, passive heat therapy could serve as a preventive measure for people at risk of adverse health outcomes during extreme heat events, improving resilience to ongoing climate change.

Irisin and exercise training in humans - results from a randomized controlled training trial.

BACKGROUND: The recent discovery of a new myokine (irisin) potentially involved in health-related training effects has gained great attention, but evidence for a training-induced increase in irisin remains preliminary. Therefore, the present study aimed to determine whether irisin concentration is increased after regular exercise training in humans. METHODS: In a randomized controlled design, two guideline conforming training interventions were studied. Inclusion criteria were age 30 to 60 years, <1 hour/week regular activity, non-smoker, and absence of major diseases. 102 participants could be included in the analysis. Subjects in the training groups exercised 3 times per week for 26 weeks. The minimum compliance was defined at 70%. Aerobic endurance training (AET) consisted of 45 minutes of walking/running at 60% heart rate reserve. Strength endurance training (SET) consisted of 8 machine-based exercises (2 sets of 15 repetitions with 100% of the 20 repetition maximum). Serum irisin concentrations in frozen serum samples were determined in a single blinded measurement immediately after the end of the training study. Physical performance provided positive control for the overall efficacy of training. Differences between groups were tested for significance using analysis of variance. For post hoc comparisons with the control group, Dunnett's test was used. RESULTS: Maximum performance increased significantly in the training groups compared with controls (controls: ±0.0 ± 0.7 km/h; AET: 1.1 ± 0.6 km/h, P < 0.01; SET: +0.5 ± 0.7 km/h, P = 0.01). Changes in irisin did not differ between groups (controls: 101 ± 81 ng/ml; AET: 44 ± 93 ng/ml; SET: 60 ± 92 ng/ml; in both cases: P = 0.99 (one-tailed testing), 1-ß error probability = 0.7). The general upward trend was mainly accounted for by a negative association of irisin concentration with the storage duration of frozen serum samples (P < 0.01, ß = -0.33). After arithmetically eliminating this confounder, the differences between groups remained non-significant. CONCLUSIONS: A training-induced increase in circulating irisin could not be confirmed, calling into question its proposed involvement in health-related training effects. Because frozen samples are prone to irisin degradation over time, positive results from uncontrolled trials might exclusively reflect the longer storage of samples from initial tests.

Association between postexercise hypotension and long-term training-induced blood pressure reduction: a pilot study.

OBJECTIVE: The interindividual variability in the efficacy of regular endurance exercise to lower blood pressure is high. Therefore, to optimize training prescriptions, predictors would be desirable. The main hypothesis of the present study was an association between postexercise hypotension after an exhaustive exercise test and chronic blood pressure reductions in response to an endurance training program. DESIGN: Uncontrolled prospective training study. SETTING: University department. PARTICIPANTS: Healthy untrained subjects were recruited by flyers. Inclusion criteria were age 30 to 60 years, body mass index 25 to 35 kg/m(2), untrained status (<1 hour/week regular activity; V[Combining Dot Above]O(2max) < 45 mL·min(-1)·kg(-1)), blood pressure 150/95 mm Hg, nonsmoker; 14 subjects were included, 12 could be analyzed. INTERVENTION: Walking/running 4 times per week at 60% heart rate reserve for 4 weeks. MAIN OUTCOME MEASURES: Difference in blood pressure from the initial resting value to 1 and 24 hours after the initial test (acute) and the resting value before the final test (chronic), respectively. RESULTS: Initial resting systolic blood pressure was 134 ± 18 mm Hg. Values were significantly reduced at all time points thereafter (1 hour: 125 ± 13 mm Hg; 24 hours: 128 ± 12 mm Hg; final: 125 ± 18 mm Hg). Acute and chronic changes correlated significantly (1 hour: P = 0.003; r = 0.77; 24 hours: P = 0.017; r = 0.67). Results for diastolic blood pressure were comparable yet less pronounced. CONCLUSIONS: The magnitude of postexercise hypotension is a promising candidate for the prediction of individual blood pressure-related training efficacy. Easily determined, it might be used to improve training prescriptions. However, further studies are needed to assess predictive accuracy.

Why Humble Farmers May in Fact Grow Bigger Potatoes: A Call for Street-Smart Decision-Making in Sport.

BACKGROUND: The main task of applied sport science is to inform decision-making in sports practice, that is, enabling practitioners to compare the expectable outcomes of different options (e.g. training programs). MAIN BODY: The "evidence" provided may range from group averages to multivariable prediction models. By contrast, many decisions are still largely based on the subjective, experience-based judgement of athletes and coaches. While for the research scientist this may seem "unscientific" and even "irrational", it is important to realize the different perspectives: science values novelty, universal validity, methodological rigor, and contributions towards long-term advancement. Practitioners are judged by the performance outcomes of contemporary, specific athletes. This makes out-of-sample predictive accuracy and robustness decisive requirements for useful decision support. At this point, researchers must concede that under the framework conditions of sport (small samples, multifactorial outcomes etc.) near certainty is unattainable, even with cutting-edge methods that might theoretically enable near-perfect accuracy. Rather, the sport ecosystem favors simpler rules, learning by experience, human judgement, and integration across different sources of knowledge. In other words, the focus of practitioners on experience and human judgement, complemented-but not superseded-by scientific evidence is probably street-smart after all. A major downside of this human-driven approach is the lack of science-grade evaluation and transparency. However, methods are available to merge the assets of data- and human-driven strategies and mitigate biases. SHORT CONCLUSION: This work presents the challenges of learning, forecasting and decision-making in sport as well as specific opportunities for turning the prevailing "evidence vs. eminence" contrast into a synergy.

Forecasting football injuries by combining screening, monitoring and machine learning.

Identifying players or circumstances associated with an increased risk of injury is fundamental for successful risk management in football. So far, time-constant and volatile risk factors are generally considered separately in either a screening (constant) or a monitoring (volatile) approach each resulting in a restricted set of explanatory variables. Consequently, improvements in predictive accuracy may be expected when screening and monitoring data are combined, especially when analysed with current machine learning (ML) techniques.This trial was designed as a prospective observational cohort study aiming to forecast non-contact time-loss injuries in male professional football (soccer). Injuries were registered according to the Fuller consensus. Gradient boosting with ROSE upsampling within a leave-one-out cross-validation was used for data analysis. The hierarchical data structure was considered throughout. Different splits of the original dataset were used to probe the robustness of results.Data of 88 players from 4 teams and 51 injuries could be analysed. The cross-validated performance of the gradient boosted model (ROC area under the curve 0.61) was promising and higher compared to models without integration of screening data. Importantly, holdout test set performance was similar (ROC area under the curve 0.62) indicating prospect of generalizability to new cases. However, the variation of predictive accuracy and feature importance with different splits of the original dataset reflects the relatively low number of events.It is concluded that ML-based injury forecasting based on the integration of screening and monitoring data is promising. However, external prospective verification and continued model development are required.

Does Higher Intensity Increase the Rate of Responders to Endurance Training When Total Energy Expenditure Remains Constant? A Randomized Controlled Trial.

BACKGROUND: Standardized training prescriptions often result in large variation in training response with a substantial number of individuals that show little or no response at all. The present study examined whether the response in markers of cardiorespiratory fitness (CRF) to moderate intensity endurance training can be elevated by an increase in training intensity. METHODS: Thirty-one healthy, untrained participants (46 ± 8 years, BMI 25.4 ± 3.3 kg m-2 and [Formula: see text]O2max 34 ± 4 mL min-1 kg-1) trained for 10 weeks with moderate intensity (3 day week-1 for 50 min per session at 55% HRreserve). Hereafter, the allocation into two groups was performed by stratified randomization for age, gender and VO2max response. CON (continuous moderate intensity) trained for another 16 weeks at moderate intensity, INC (increased intensity) trained energy-equivalent for 8 weeks at 70% HRreserve and then performed high-intensity interval training (4 × 4) for another 8 weeks. Responders were identified as participants with VO2max increase above the technical measurement error. RESULTS: There was a significant difference in [Formula: see text]O2max response between INC (3.4 ± 2.7 mL kg-1 min-1) and CON (0.4 ± 2.9 mL kg-1 min-1) after 26 weeks of training (P = 0.020). After 10 weeks of moderate training, in total 16 of 31 participants were classified as VO2max responders (52%). After another 16 weeks continuous moderate intensity training, no further increase of responders was observed in CON. In contrast, the energy equivalent training with increasing training intensity in INC significantly (P = 0.031) increased the number of responders to 13 of 15 (87%). The energy equivalent higher training intensities increased the rate of responders more effectively than continued moderate training intensities (P = 0.012). CONCLUSION: High-intensity interval training increases the rate of response in VO2max to endurance training even when the total energy expenditure is held constant. Maintaining moderate endurance training intensities might not be the best choice to optimize training gains. Trial Registration German Clinical Trials Register, DRKS00031445, Registered 08 March 2023-Retrospectively registered, https://www.drks.de/DRKS00031445.

Individualised reference ranges for markers of muscle recovery assessment in soccer.

Recently an individualisation algorithm has been developed and shown to significantly improve the diagnostic accuracy of creatine kinase (CK) and urea in endurance sports and Badminton. In this study, the applicability and benefit of this algorithm was evaluated using repeated measures data from 161 professional German soccer players monitored during the 2015-2017 seasons. Venous blood samples were collected after a day off (recovered state) and after a minimum of two strenuous training sessions within 48 h (non-recovered state) and analysed for CK and urea. Group-based reference ranges were derived from that same dataset to ensure the best possible reference for comparison. A z-test was conducted to analyse differences in error rates between individualised and group-based classifications. CK values for the individualised approach showed significantly lower error rates in the assessment of muscle recovery compared to both a population-based (p < .001; z-value: -17.01; test-pass error rate: 21 vs. 67%; test-fail: 19 vs. 64%) and a group-based cut-off (p < .001; z-value: -15.29; test-pass error rate: 65%; test-fail: 67%). It could be concluded that the assessment of muscle recovery in soccer using individualised interpretations of blood-borne markers may offer higher diagnostic accuracy than a population-based and a sample-specific group-based approach.HighlightsAssessing muscle recovery via CK using individualised ranges seems to offer a higher diagnostic accuracy than a sample-specific group-based analysis.Using an individualised algorithm seems to be a promising approach to overcome diagnostic problems arising from large inter- and intraindividual variability in blood parameters as it significantly improved the diagnostic accuracy of CK as a recovery marker.As recovery assessment in elite soccer ultimately aims at the accurate detection of differences in the individual player this algorithm seems to offer coaches and sport scientists a more sensitive approach compared to group-specific evaluations.

Endotoxin Tolerance Acquisition and Altered Hepatic Fatty Acid Profile in Aged Mice.

(1) Background: Aging is linked to an altered immune response and metabolism. Inflammatory conditions, such as sepsis, COVID-19, and steatohepatitis are more prevalent in the elderly and steatosis is linked both to severe COVID-19 and sepsis. We hypothesized that aging is linked to a loss of endotoxin tolerance, which normally protects the host from excessive inflammation, and that this is accompanied by elevated levels of hepatic lipids. (2) Methods: An in vivo lipopolysaccharide (LPS) tolerance model in young and old mice was used and the cytokine serum levels were measured by ELISA. Cytokine and toll-like receptor gene expression was determined by qPCR in the lungs and the liver; hepatic fatty acid composition was assessed by GC-MS. (3) Results: The old mice showed a distinct potential for endotoxin tolerance as suggested by the serum cytokine levels and gene expression in the lung tissue. Endotoxin tolerance was less pronounced in the livers of the aged mice. However, the fatty acid composition strongly differed in the liver tissues of the young and old mice with a distinct change in the ratio of C18 to C16 fatty acids. (4) Conclusions: Endotoxin tolerance is maintained in advanced age, but changes in the metabolic tissue homeostasis may lead to an altered immune response in old individuals.