Training loads and microcycle periodisation in Italian Serie A youth soccer players.

Microcycles are fundamental structures for training prescription and load management, helping to optimise training effects and performance. This study quantified external and internal loads of Italian Serie A youth soccer players across competitive weeks and their periodisation within microcycles. Data were collected from 90 players belonging to four age groups (under-19, -17, -16, -15) across a season. Methods of monitoring external [duration and global navigation satellite systems (GNSS)] and internal load [heart rate (HR) and rating of perceived exertion (RPE)] were employed. Linear mixed models determined differences in training loads across age groups, training days and player positions. Under-19 and under-17 players trained five times per week, while younger players trained four times. Late-stage academy players (under-19 and -17) demonstrated higher weekly accumulated external and sRPE training load compared to their younger counterparts (p < 0.05 between groups). Weekly accumulated HR internal loads were higher in under-15 players (p < 0.05 between groups). Marked fluctuations of daily load were observed across microcycles in under-19 and under-17 groups (p < 0.05 between days). These findings highlight progressive increases in training load throughout the development pathway, with late-stage academy players training with higher frequency, volume and marked periodisation compared to younger players.

Does a broad-spectrum cannabidiol supplement improve performance in a 10-min cycle ergometer performance-test?

Cannabidiol (CBD) is a non-intoxicating phytocannabinoid which has been proposed to possess anti-inflammatory and analgesic properties. Given the potential for perceptions of pain to limit exercise performance, the aim of the present study was to investigate if 3 weeks of daily CBD supplementation (150 mg day-1) improved performance in a 10-min performance-trial on a cycle ergometer. In a randomized, double-blind and placebo-controlled study, 22 healthy participants (n = 11 male and n = 11 female) completed two 10-min performance trials on a WattBike cycle ergometer interspersed with a 3-week supplementation period. Supplementation involved either 150 mg day-1 oral CBD or 150 mg day-1 of a visually identical placebo (PLA). During trials, ratings of perceived exertion (RPE [6-20]), heart rate (HR) and blood lactate (BLa) were collected every 2 min. Mean power (W) was also taken throughout the exercise at each time point. All data were analyzed using two-way ANOVAs. There were no significant differences (P > 0.05) between CBD or PLA groups for mean power (W) during the 10-min performance trial. There were also no significant differences (P > 0.05) in any of the physiological or perceptual parameters (HR, BLa and RPE) between conditions. Three weeks supplementation of a broad-spectrum CBD supplement did not improve performance via any change in RPE during a 10-min time trial on a cycle ergometer, and as such, this evidence does not support the claim that broad-spectrum CBD supplements could be performance-enhancing in this exercise modality.

Implications of Heat Stress-induced Metabolic Alterations for Endurance Training.

Inducing a heat-acclimated phenotype via repeated heat stress improves exercise capacity and reduces athletes̓ risk of hyperthermia and heat illness. Given the increased number of international sporting events hosted in countries with warmer climates, heat acclimation strategies are increasingly popular among endurance athletes to optimize performance in hot environments. At the tissue level, completing endurance exercise under heat stress may augment endurance training adaptation, including mitochondrial and cardiovascular remodeling due to increased perturbations to cellular homeostasis as a consequence of metabolic and cardiovascular load, and this may improve endurance training adaptation and subsequent performance. This review provides an up-to-date overview of the metabolic impact of heat stress during endurance exercise, including proposed underlying mechanisms of altered substrate utilization. Against this metabolic backdrop, the current literature highlighting the role of heat stress in augmenting training adaptation and subsequent endurance performance will be presented with practical implications and opportunities for future research.

An exercise physiologist's guide to metabolomics.

The field of exercise physiology has undergone significant technological advancements since the pioneering works of exercise physiologists in the early to mid-20th century. Historically, the ability to detect metabolites in biofluids from exercising participants was limited to single-metabolite analyses. However, the rise of metabolomics, a discipline focused on the comprehensive analysis of metabolites within a biological system, has facilitated a more intricate understanding of metabolic pathways and networks in exercise. This review explores some of the pivotal technological and bioinformatic advancements that have propelled metabolomics to the forefront of exercise physiology research. Metabolomics offers a unique 'fingerprint' of cellular activity, offering a broader spectrum than traditional single-metabolite assays. Techniques, including mass spectrometry and nuclear magnetic resonance spectroscopy, have significantly improved the speed and sensitivity of metabolite analysis. Nonetheless, challenges persist, including study design and data interpretation issues. This review aims to serve as a guide for exercise physiologists to facilitate better research design, data analysis and interpretation within metabolomics. The potential of metabolomics in bridging the gap between genotype and phenotype is emphasised, underscoring the critical importance of careful study design and the selection of appropriate metabolomics techniques. Furthermore, the paper highlights the need to deeply understand the broader scientific context to discern meaningful metabolic changes. The emerging field of fluxomics, which seeks to quantify metabolic reaction rates, is also introduced as a promising avenue for future research.

Patellar Tendon Adaptations to Downhill Running Training and Their Relationships With Changes in Mechanical Stress and Loading History.

ABSTRACT: Bontemps, B, Gruet, M, Louis, J, Owens, DJ, Miríc, S, Vercruyssen, F, and Erskine, RM. Patellar tendon adaptations to downhill running training and their relationships with changes in mechanical stress and loading history. J Strength Cond Res 38(1): 21-29, 2024-It is unclear whether human tendon adapts to moderate-intensity, high-volume long-term eccentric exercise, e.g., downhill running (DR) training. This study aimed to investigate the time course of patellar tendon (PT) adaptation to short-term DR training and to determine whether changes in PT properties were related to changes in mechanical stress or loading history. Twelve untrained, young, healthy adults (5 women and 7 men) took part in 4 weeks' DR training, comprising 10 sessions. Running speed was equivalent to 60-65% V̇O2max, and session duration increased gradually (15-30 minutes) throughout training. Isometric knee extensor maximal voluntary torque (MVT), vastus lateralis (VL) muscle physiological cross-sectional area (PCSA) and volume, and PT CSA, stiffness, and Young's modulus were assessed at weeks 0, 2, and 4 using ultrasound and isokinetic dynamometry. Patellar tendon stiffness (+6.4 ± 7.4%), Young's modulus (+6.9 ± 8.8%), isometric MVT (+7.5 ± 12.3%), VL volume (+6.6 ± 3.2%), and PCSA (+3.8 ± 3.3%) increased after 4 weeks' DR (p < 0.05), with no change in PT CSA. Changes in VL PCSA correlated with changes in PT stiffness (r = 0.70; p = 0.02) and Young's modulus (r = 0.63; p = 0.04) from 0 to 4 weeks, whereas changes in MVT did not correlate with changes in PT stiffness and Young's modulus at any time point (p > 0.05). To conclude, 4 weeks' DR training promoted substantial changes in PT stiffness and Young's modulus that are typically observed after high-intensity, low-volume resistance training. These tendon adaptations seemed to be driven primarily by loading history (represented by VL muscle hypertrophy), whereas increased mechanical stress throughout the training period did not seem to contribute to changes in PT stiffness or Young's modulus.