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The anaerobic speed reserve (ASR) is a popular method of profiling soccer players, often used to individualize training prescription. This study explored the reliability of ASR profiling, and the relationship between the ASR and acute physiological responses to highintensity interval training (HIIT). Acute physiological responses to different HIIT types were also compared. Thirteen subelite female soccer players aged 20.2 6 4.6 years completed 6 exercise sessions. In sessions 1-2, players completed a 40-m sprint to assess maximal sprint speed (MSS) and 1600-m time-trial to estimate maximal aerobic speed (MAS), which were used to calculate ASR and assess test-retest reliability. In sessions 3-6, players completed 4 HIIT sessions (repeated-sprint training, sprint interval training, long intervals, and short intervals HIIT). Intensities for long and short intervals HIIT were individualized according to MAS. Ratings of perceived exertion (RPE), heart rate (HR), and postsession blood lactates were recorded throughout. Relationships between the ASR and acute responses to HIIT, and between HIIT session comparisons in outcome measures were assessed. Anaerobic speed reserve (coefficient of variation 6 95% confidence limits; 3.1 6 1.5%), MAS (1.8 6 1.3%), and MSS (0.8 6 0.6%) indicated acceptable reliability. Moderate correlations between ASR and RPE (r 5 0.33), postsession blood lactate (r 5 0.34), and HR (r 5 0.37) were observed during long intervals HIIT. A strong correlation was observed between ASR and RPE during SIT (r 5 0.50). Sprint interval training elicited higher RPE's and postsession blood lactate's than other HIIT sessions. Anaerobic speed reserve has good reliability and may influence acute physiological responses to HIIT in female soccer players. [ABSTRACT FROM AUTHOR]

Purpose: Exercise has transient effects on the immune system that could influence infection risk and tissue recovery after exercise. Little is known about how the menstrual cycle interacts with the immune responses to acute exercise. This exploratory study sought to evaluate the effect of menstrual-cycle phase on peripheral blood mononuclear cell counts before and immediately after a bout of intense aerobic exercise. Methods: Seven naturally menstruating women (age: 27 [3] y) completed three 5-km cycling time trials coinciding with the early-follicular, late-follicular, and mid-luteal stage, confirmed by hormonal measurement. Venous blood samples were taken and examined for the presence of immune cell types using flow cytometry. Results: Reductions in circulating CCR7+CD45RA+ naïve CD4+ T cells, CD4+CD25+ regulatory T cells, and CD56+CD57+ natural killer cells observed during the early-follicular phase were attenuated when exercise was performed during the late-follicular phase. Similarly, reductions in circulating CD56+CD57+ natural killer cells and CD14+TLR4+ monocytes following exercise in the early-follicular phase were abolished when exercise was performed in the midluteal phase. Conclusions: These preliminary findings indicate that the effect of acute high-intensity exercise on immune-cell mobilization and activation varies across the menstrual cycle, potentially impacting the anti-inflammatory effects of regulatory T cells and the cell-mediated effects of both natural killer CD57+ cells and monocytes expressing TLR4. [ABSTRACT FROM AUTHOR]

This study examined the type, frequency, and severity of symptoms experienced by naturally menstruating women and combined, monophasic, oral contraceptive pill users and their perceived effects on exercise performance and recovery time posttraining. Forty-two recreationally active women; 21 naturally menstruating and 21 combined, monophasic, oral contraceptive pill users participated in the study. Data were collected using two approaches: (a) an online 54-part retrospective survey and (b) a daily questionnaire. "Total number of symptoms," "symptom index score," "average symptom severity," and "symptom index × severity score" were calculated from the retrospective data set. Real-time symptom data (i.e., "symptom frequency per phase" and "phase symptom frequency × severity score") were calculated across predefined cycle phases from the daily questionnaire. The retrospective survey showed that symptoms were commonly reported by recreationally active women, but there were no differences in symptomology between the groups (p >.113). The daily questionnaire showed both groups experienced a greater frequency and severity of symptoms while bleeding (p ≤.001), which was associated with perceived reductions in exercise performance (odds ratio = 1.04–1.07) and a perceived longer recovery time posttraining (odds ratio = 1.03–1.04). The results from this study show that cycle-related symptoms were commonly reported by a group of recreationally active women, with no difference in symptomology between naturally menstruating women and combined, monophasic, oral contraceptive pill users. The magnitude of symptoms was greater while bleeding, which was associated with a perceived reduction in exercise performance and a longer recovery time posttraining. [ABSTRACT FROM AUTHOR]

Inter-limb asymmetry refers to an imbalance in performance between the left and right limbs. Discrepancies throughout asymmetry research does not allow practitioners to confidently understand the effect of inter-limb asymmetries on athletic performance. Therefore, this review summarized the current literature using a meta-analytic approach, conforming to the Preferred Reporting Items for Systematic Review and Meta-Analyses guidelines to identify the association between inter-limb asymmetry and athletic performance. A literature search using PubMed, Web of Science and SPORTDiscus databases yielded 11-studies assessing the effect of inter-limb asymmetries, measured via unilateral jump performance, on bilateral jump, change of direction (COD) and sprint performance in adult sports players. The quality of evidence was assessed via a modified Downs and Black checklist and in compliance with the Grading of Recommendations Assessment Development and Evaluation. Correlation coefficients were transformed via Fishers z (Zr), meta-analysed and then re-converted to correlation coefficients. Egger's regression presented no significant risk of bias. Vertical jump performance was not significantly affected by asymmetry (Zr = 0.053, r = 0.05; P = 0.874), whereas COD and sprint both presented significant weak associations (COD, Zr = 0.243, r = 0.24; Sprint, Zr = 0.203, r = 0.2; P < 0.01). The results demonstrate that inter-limb asymmetries seem to present a negative impact to COD and sprint performance but not vertical jump performance. Practitioners should consider implementing monitoring strategies to identify, monitor and possibly address inter-limb asymmetries, specifically for performance tests underpinned by unilateral movements such as COD and sprint performance. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effectiveness between cold-water immersion (CWI) and phase-change-material (PCM) cooling on intramuscular, core, and skin-temperature and cardiovascular responses. Methods: In a randomized, crossover design, 11 men completed 15 min of 15°C CWI to the umbilicus and 2-h recovery or 3 h of 15°C PCM covering the quadriceps and 1 h of recovery, separated by 24 h. Vastus lateralis intramuscular temperature at 1 and 3 cm, core and skin temperature, heart-rate variability, and thermal comfort were recorded at baseline and 15-min intervals throughout treatment and recovery. Results: Intramuscular temperature decreased (P < .001) during and after both treatments. A faster initial effect was observed from 15 min of CWI (A: 4.3°C [1.7°C] 1 cm; 5.5°C [2.1°C] 3 cm; P= .01). However, over time (2 h 15 min), greater effects were observed from prolonged PCM treatment (Δ: 4.2°C [ 1,9°C] 1 cm; 2.2°C [2.2°C] 3 cm; treatment x time, P = .0001). During the first hour of recovery from both treatments, intramuscular temperature was higher from CWI at 1 cm (P = .013) but not 3 cm. Core temperature deceased 0.25° (0.32°) from CWI (P = .001) and 0.28°C (0.27°C) from PCM (P = .0001), whereas heart-rate variability increased during both treatments (P = .001), with no differences between treatments. Conclusions: The magnitude of temperature reduction from CWI was comparable with PCM, but intramuscular temperature was decreased for longer during PCM. PCM cooling packs offer an alternative for delivering prolonged cooling whenever application of CWI is impractical while also exerting a central effect on core temperature and heart rate. [ABSTRACT FROM AUTHOR]

Purpose: To compare the dose–response relationship between traditional arbitrary speed thresholds versus an individualized approach, with changes in aerobic fitness in professional youth soccer players. Methods: A total of 14 youth soccer players completed a 1500-m time trial to estimate maximal aerobic speed (MAS, km·h−1) at the start and at the end of a 6-week period. Training load was monitored on a daily basis during this study. External load measures were total distance covered and total acceleration and deceleration distance >2 m·s−2. Arbitrary high-speed running measures were meters covered and time spent at >17 km·h−1 (m > high-speed distance, t > high-speed distance) and 21 km·h−1 (m > very-high-speed distance, t > very-high-speed distance). Individualized high-speed running measures were meters covered and time spent at >MAS km·h−1 (m > MAS, t > MAS) and 30% anaerobic speed reserve (m > 30ASR, t > 30ASR). In addition, internal load measures were also collected: heart rate exertion and rating of perceived exertion. Linear regression analysis was used to establish the dose–response relationship between mean weekly training load and changes in aerobic fitness. Results: Very large associations were found between t > MAS and changes in aerobic fitness (R2 =.59). Large associations were found for t > 30ASR (R2 =.38) and m > MAS (R2 =.25). Unclear associations were found for all other variables. Conclusion: An individualized approach to monitoring training load, in particular t > MAS, may be a more appropriate method than using traditional arbitrary speed thresholds when monitoring the dose–response relationship between training load and changes in aerobic fitness. [ABSTRACT FROM AUTHOR]

Runners commonly utilize cryotherapy as part of their recovery strategy. Cryotherapy has been ineffective in mitigating signs and symptoms of muscle damage following marathon running and is limited by its duration of application. Phase change material (PCM) packs can prolong the duration of cooling. This study aimed to test the efficacy of prolonging the duration of cooling using PCM on perceptual recovery, neuromuscular function, and blood markers following a marathon run. Thirty participants completed a marathon run and were randomized to receive three hours of 15°C PCM treatment covering the quadriceps or recover without an intervention (control). Quadriceps soreness, strength, countermovement jump (CMJ) height, creatine kinase (CK), and high sensitivity C‐reactive protein (hsCRP) were recorded at baseline, 24, 48, and 72 hours after the marathon. Following the marathon, strength decreased in both groups (P <.0001), with no difference between groups. Compared to baseline, strength was reduced 24 (P =.004) and 48 hours after the marathon (P =.008) in the control group, but only 24 hours (P =.028) in the PCM group. Soreness increased (P <.0001) and CMJ height decreased (P <.0001) in both groups, with no difference between groups. Compared to baseline, CMJ height was not reduced on any days in the PCM group but was reduced in the control group 24 (P <.0001) and 48 hours (P =.003) after the marathon. CK and hsCRP increased in both groups (P <.0001). Although the marathon run induced significant muscle damage, prolonging the duration of cooling using PCM did not accelerate the resolution of any dependent variables. [ABSTRACT FROM AUTHOR]

Habitual use of eccentric exercise has been recognised to increase strength and power; however, the current body of knowledge has limited potential to understand the application of such resistance training in athletic populations. In order to develop appropriate applied research, that relates to elite athletic populations, it is vital to appreciate the practical knowledge of strength and conditioning practitioners operating in high-performance environments. This study summarised the questionnaire responses from 100 strength and conditioning practitioners operating in performance sport relating to questions such as the training effects to various eccentric resistance training regimes, the rationale for the use of these techniques and the knowledge supporting its application. The combination of closed and open-ended questions enabled a thematic analysis to be conducted. There was evidence that practitioners employed a variety of eccentric training methodologies; however, there was interest in gaining greater understanding of the training dose to bring about the optimal adaptive changes, and importantly how this might translate to sport-specific performance. In addition, practitioners would welcome recommendations associated with eccentric training, whilst concurrently minimising the issues of excessive fatigue, muscle damage and soreness. The training effects of interest included neural, architectural and morphological adaptations and, importantly, translation to performance of sports-specific skills. Collectively, these responses called for more practically relevant research to be conducted within the high-performance environment, alongside more opportunities for professional development through learning and knowledge-sharing opportunities. The outcomes summarised in this work should inform future applied research projects and educational content relating to eccentric training. [ABSTRACT FROM AUTHOR]