Search Results (209)

Background/Objectives: Exercise-induced muscle damage, inflammation, oxidative stress, and accumulated fatigue affect post-exercise recovery and long-term training adaptations in athletes. Consequently, nutritional strategies supporting recovery have gained attention in sports nutrition. Among emerging compounds, adaptogens have attracted particular interest due to their potential anti-fatigue, antioxidant, and sleep-enhancing properties. However, evidence in trained athletes remains limited. Therefore, the aim of this narrative review is to summarize the current scientific evidence regarding the use of selected adaptogens in sport and to evaluate their potential roles in exercise recovery, training adaptation and exercise performance. Particular attention is given to Withania somnifera (ashwagandha), Panax species, Rhodiola rosea and Cordyceps species. Furthermore, this review discusses the practical implications and current limitations of the available evidence for athletes and sports practitioners. Conclusions: Current evidence from a limited number of heterogeneous studies suggests that selected standardized adaptogen preparations may provide beneficial effects on specific exercise-recovery-related outcomes and selected aspects of exercise performance in trained athletes. Among the adaptogens discussed, most consistent evidence concerns Withania somnifera, whereas the evidence for Panax species, Rhodiola rosea and Cordyceps species remains limited and should be considered preliminary. Furthermore, the available literature is characterized by a limited number of studies conducted in trained athletes, the underrepresentation of female athletes, and considerable heterogeneity in extract composition and supplementation protocols. Consequently, the current evidence is insufficient to formulate definitive recommendations regarding the efficacy, optimal dosage, or long-term safety of adaptogen supplementation. Further well-designed randomized controlled trials are required to establish evidence-based recommendations. Full article

Background: Relative energy deficiency in sport (REDs) is a multi-system syndrome precipitated by sustained low energy availability (LEA) and known to perturb bone, muscle, adipose, endocrine, and fluid–electrolyte homeostasis in athletic populations. Research question: How does chronic exercise-induced LEA modify the four principal compartments of body composition—bone mineral density, skeletal muscle mass, adipose (total and visceral) tissue, and hydration status—and to what extent do these modifications differ across endurance, strength, and aesthetic sporting disciplines? Objective: The objective of this narrative review was to synthesise the post-2000 peer-reviewed literature addressing this question, to delineate sex- and sport-specific patterns of compositional change, and to appraise the evidence base underpinning current nutritional and screening recommendations. Methods: A structured search of PubMed, Web of Science, Scopus, and Google Scholar (January 2000–June 2026) was performed; 85 sources specific to REDs, body composition, and athletes met the pre-specified inclusion criteria and informed the synthesis (104 references are cited in total, including background and methodological sources), the reporting of which was guided by the SANRA framework. Scope: The review integrates physiological, endocrine, and nutritional evidence across both sexes, contrasts REDs risk across endurance, ultra-endurance, weight-category/aesthetic, speed–power, and team disciplines and addresses practical implications for screening, interdisciplinary care, and future research. Full article

Aim: Asprosin, a white adipose tissue-derived glucogenic adipokine, and spexin, a satiety-promoting neuropeptide, are dysregulated in obesity, yet their collective modulation by structured exercise and nutritional supplementation remains poorly characterized. This trial investigated the effects of 12 weeks of combined aerobic–resistance training, with and without taurine supplementation, on plasma asprosin, spexin, and body composition in obese men. Methods: Forty-four obese men (BMI ≥ 30 kg/m²) were allocated in a randomized, placebo-controlled, supplement-blinded design to control plus placebo (CON), taurine supplementation alone (SUP; 3 g/day), exercise plus placebo (EX), or exercise plus taurine (EX + SUP; n = 11 per group). The 12-week protocol combined aerobic training at 60% heart rate reserve (Karvonen formula) with progressive resistance training at 60% of one-repetition maximum, with load re-estimated every four weeks. Plasma asprosin and spexin were quantified by ELISA; body fat percentage (BFP) was assessed by bioelectrical impedance analysis. Two-way repeated-measures ANOVA with Bonferroni post hoc correction and Cohen’s d effect size estimation were applied throughout. Results: Significant Group × Time interactions were detected for all five outcomes (all p < 0.05). EX + SUP generated the greatest reductions in plasma asprosin (Δ = −11.20 ng/mL, p < 0.001), body mass (Δ = −5.50 kg, p = 0.003), BMI (Δ = −1.80 kg/m², p = 0.002), and BFP (Δ = −4.90%, p < 0.001), together with the greatest elevation in plasma spexin (Δ = +0.29 ng/mL, p < 0.001); effect sizes were large across all EX + SUP outcomes (Cohen’s d = 1.17 to ≥1.87). CON showed no significant change in any variable (all p > 0.05). Conclusions: Combined aerobic–resistance training with taurine supplementation produced statistically superior, large-magnitude improvements in adipokine regulation and body composition relative to either modality in isolation, demonstrating greater improvements in the combined intervention group compared with either modality applied independently. Given the per-group sample of n = 11, these findings should be considered preliminary and exploratory; independent replication in larger, adequately powered trials is required before any clinical translation can be considered. Full article

Exercise generally elicits changes in bone and inflammatory biomarkers, but it is unclear if these changes are related. The purpose of this secondary analysis was to investigate associations between bone and inflammatory biomarkers before and after a single bout of high-intensity/impact exercise and post-exercise nutrition. In a repeated measures crossover design, 13 healthy, young adult females (age = 20.3 ± 2.3 y) performed high-intensity resistance and impact exercise followed by nutrient consumption (skim milk and an isoenergetic carbohydrate beverage). Venous blood was obtained pre-exercise, 15 min, 75 min, 24 h, and 48 h post-exercise. Serum bone biomarkers (cross-linked C-telopeptide of type I collagen [CTX], receptor activator of NF-κB ligand [RANKL], sclerostin [SOST], osteoprotegerin [OPG], total osteocalcin [OC]) and cytokines (interleukin [IL]-1β, IL-6, IL-10, and tumor necrosis factor-alpha [TNF-α]) were measured. Separate linear mixed regression models were performed for each bone biomarker. There were significant associations between bone and inflammatory biomarkers, including CTX with TNF-α (positive) and IL-10 (negative), OPG with TNF-α (negative) and IL-10 (positive), RANKL with IL-6 (positive) and SOST with TNF-α (negative) and IL-10 (positive). Thus, relationships exist between inflammatory and bone biomarkers in the context of an exercise and nutrition stimulus, which may have implications for optimizing exercise recovery strategies. Full article

Background: Marathon running triggers a robust systemic inflammatory response. Whether habitual dietary fat composition modulates pre-race cytokine concentrations or the magnitude and recovery of the exercise-induced inflammatory response remains unknown. Methods: Thirty-one recreational marathon runners (58.1% female; mean age 38.4 ± 10.2 years) completed the Diet History Questionnaire III to assess habitual dietary fat intake—including chain-length-specific SFA, MFA, PFA, trans fatty acids, and CLA—over the preceding three months. Circulating IFN-γ, IL-1β, IL-4, IL-6, IL-10, and TNF-α were measured pre-race, immediately post-race, and 48 h post-race. Repeated measures ANOVA examined cytokine changes; multivariable regression models estimated fat–cytokine associations adjusted for 11 pre-specified covariates, with Benjamini–Hochberg FDR correction applied across all models. Results: IL-6 rose markedly post-race (p < 0.001, generalized η² = 0.615) before returning to pre-race levels by 48 h. IL-10 followed a similar trajectory (p < 0.001, generalized η² = 0.346). TNF-α showed a borderline non-significant trend (p = 0.056); IFN-γ, IL-1β, and IL-4 did not change significantly. MFA 20:1 was positively associated with IFN-γ concentrations at 48 h post-race (β = 13.66; 95% CI: 8.94, 18.38, p < 0.01, q = 0.04) and TNF-α (β = 9.14; 95% CI: 6.43, 11.86, p < 0.01, q = 0.02). Conclusions: Habitual intake of the long-chain monounsaturated fatty acid 20:1 was positively associated with IFN-γ and TNF-α at 48 h post-race. This pattern, emerging specifically at the 48 h post-race phase, suggests that the post-race period, once acute exercise-induced signaling has subsided, may be a window in which habitual dietary fat quality is most detectable in relation to circulating cytokines. Habitual fat quality may warrant consideration in future endurance recovery nutrition research. This exploratory finding calls for replication in larger cohorts. Full article

Caffeine is among the most widely used supplements in sports nutrition, with substantial evidence supporting its efficacy for enhancing athletic performance. However, the relevance of pre-exercise caffeine supplementation extends beyond its ergogenic effects. Exercise itself acts as an acute cardiometabolic stressor, eliciting dynamic responses in blood pressure, heart rate, vascular tone, substrate utilization, and glucose regulation. Caffeine may further modify the magnitude, temporal profile, and recovery kinetics of these responses. This focused narrative review examines the acute cardiometabolic responses associated with pre-exercise caffeine supplementation and its potential regulatory effects. It outlines the underlying biological mechanisms, including adenosine receptor antagonism, hemodynamic and vascular pathways, and metabolic and substrate-utilization pathways, while synthesizing current evidence from the literature. Available evidence indicates that the acute effects of caffeine are highly context dependent. In some exercise settings, caffeine may promote lipolysis and fat oxidation; in others, particularly among susceptible individuals or under specific exercise conditions, it may be associated with greater acute cardiovascular or autonomic load, reflected by higher peripheral vascular resistance and blood pressure, altered vascular reactivity, or delayed post-exercise autonomic recovery. Its effects may vary according to dose, timing, supplement form, exercise modality and intensity, training status, habitual caffeine intake, genotype, sex, and hormonal status. Overall, pre-exercise caffeine should not be regarded solely as a uniformly beneficial ergogenic aid, but rather as a physiological modulator that may reshape the acute cardiometabolic milieu during and after exercise. Future studies should integrate hemodynamic, vascular, metabolic, and individual-variability measures over extended observation periods to support more evidence-based and individualized guidance on the appropriate use of pre-exercise caffeine. Full article

Declines of skeletal muscle mass and functions are implicated in the progression of various clinical conditions such as cancers, obesity, insulin resistance, diabetes, and osteoporosis. While no effective and safe drugs against muscle wasting, such as sarcopenia and disease-associated cachexia, have been discovered, it is well documented that dietary essential amino acids (EAAs) or high-quality protein work synergistically to enhance the anabolic effect of resistance exercise training (RT), leading to gains in muscle mass, strength, and muscle quality. Dietary EAAs serve as precursors and signaling molecules for the synthesis of new muscle proteins (both contractile and mitochondrial) and stimulate neuromuscular junction remodeling. Furthermore, EAAs consumed in the post-absorptive state improve endurance capacity via stimulation of mitochondrial biogenesis (independent of PGC1-α) and mitochondrial dynamics (mitochondrial protein synthesis and fission). Here, we discuss (1) traditional molecular mechanisms regulating the muscle proteome through constant turnover (synthesis and breakdown), (2) novel mechanisms by which dietary supplementation of EAAs during RT simultaneously improves muscle strength and endurance, (3) stable isotope tracer methodologies that enable understanding of the dynamic muscle proteome and accurate assessment of functional muscle mass, and finally, (4) clinical implications of combined EAA and RT interventions in the context of muscle and metabolic dysfunction, including sarcopenia, cachexia, obesity, and chronic disease. Collectively, current evidence underscores the potential of balanced EAAs, particularly when combined with resistance training, as a safe, effective, and translationally relevant nutritional strategy to preserve and enhance muscle and metabolic health across healthy and clinical populations. Full article

Background/Objectives: Lifestyle Modification Programs (LMPs) based on exercise and nutrition aim to prevent/manage chronic diseases and foster well-being. However, moving LMPs from research to medical practice can be challenging, as programs must be both effective and feasible. The primary goal of this study was to assess cardiorespiratory fitness (CRF) changes according to an LMP, measured through VO_2max, as a key indicator of health outcomes and intervention efficacy. Methods: In this single-arm intervention study, 100 subjects were enrolled; per-protocol analysis of main parameters was performed on 85 participants (15 were excluded due to medical/technical reasons). A feasible intervention program (of low resource intensity with only two physician/patient encounters) provided personalized exercise prescription, optimized nutritional habits based on the Mediterranean diet and Healthy Eating Plate principles, and supported behaviour change. We assessed CRF through VO_2max, a key indicator of health outcomes and intervention efficacy. We also analyzed, using regression analysis, the relationship between VO_2max (the gold-standard measure of CRF) and MET_Speak, a simpler, feasible parameter of CRF derived from Exercise Stress Testing. Body composition (BC) and AHA diet score were also measured at baseline and post-6-month intervention. Statistical analyses included paired comparisons and multivariable regression to explore factors influencing CRF changes. Results: Analysis on the primary outcome, VO_2max, was performed according to the intention-to-treat principle and per-protocol. This feasible protocol resulted in a significant increase in VO_2max, improvements in fat-free mass, and a reduction in fat mass. Overall, 42.4% of participants achieved an improvement of ≥1 MET, a change previously associated with reduced mortality risk. Older participants tend to experience smaller improvements in VO_2max. Conclusions: Although observing an improvement in CRF and BC following an LMP is not surprising, the strength of the study is to show the feasibility of implementing an effective, feasible LMP into clinical routine, supporting the integration of such programs into clinical practice. Full article

Background/Objectives: Soccer involves high physiological demands that induce neuromuscular fatigue, muscle damage, inflammation, and oxidative stress, impairing recovery between training sessions and competitions. Polyphenols have been proposed as a nutritional strategy to modulate these responses; however, evidence in soccer players is limited and heterogeneous. This systematic review aimed to synthesize the evidence on the effects of polyphenol supplementation on post-exercise recovery in adult male soccer players. Methods: A systematic review was conducted following PRISMA guidelines, with a protocol registered in the Open Science Framework. Randomized controlled trials (RCTs) evaluating polyphenol supplementation versus placebo on post-exercise recovery in adult soccer players were included. Searches were performed in PubMed, Scopus, Web of Science, and the Cochrane Library up to April 2026. Risk of bias was assessed using RoB 2, and certainty of evidence using GRADE. Due to heterogeneity, a qualitative synthesis was conducted. Results: Eight RCTs were included. Interventions involved tart cherry juice, pomegranate juice, beetroot juice, curcumin, and tea extracts. Evidence was inconsistent for biomarkers of muscle damage, inflammation, and oxidative stress, with most studies reporting no significant differences versus placebo. In contrast, beneficial trends for perceptual outcomes, particularly reduced muscle soreness and improved subjective well-being, were mainly observed in studies using tart cherry juice, beetroot juice, and curcumin. Evidence for oxidative stress and functional recovery was limited and heterogeneous. Certainty of evidence was low for most outcomes and very low for oxidative stress and functional recovery. Conclusions: Polyphenol supplementation, particularly tart cherry juice, beetroot juice, and curcumin, may improve perceptual recovery in adult male soccer players, particularly by reducing muscle soreness and enhancing subjective well-being. However, evidence on physiological biomarkers and functional recovery remains inconsistent and of low certainty. Further well-designed RCTs are required to establish robust recommendations in competitive soccer. Full article

Background/Objectives: Global population aging is associated with a rising prevalence of malnutrition among adults aged ≥80 years. Gut dysbiosis is linked to immune decline and impaired nutrient absorption, and aerobic exercise may enhance microbial diversity. This study investigated gut microbiota changes after a 12-week aerobic exercise intervention in octogenarians stratified by nutritional status. Methods: A total of 129 nursing home residents (≥80 years) were classified via the Mini Nutritional Assessment Short-Form (MNA-SF) into a healthy group (HG, MNA-SF ≥ 11) and a malnourished group (MG, MNA-SF < 11). Both groups underwent a 12-week brisk walking intervention (three sessions/week, 1 h/session, 40–60% heart rate reserve). Fecal samples were collected at baseline and post-intervention and were analyzed via shotgun metagenomic sequencing. Results: A total of 36 participants completed the intervention (HG = 17, MG = 19). Within-group baseline-to-post-intervention analysis showed no significant changes in alpha or beta diversity in the MG. However, post-intervention between-group comparison revealed higher microbial richness and diversity in the MG vs. the HG, with enrichment of taxa including Faecalibacterium prausnitzii and Streptococcus salivarius. Functional analysis revealed significant enhancements in metabolic pathways related to amino acid biosynthesis, protein synthesis, and quorum sensing in the MG. In contrast, the HG showed limited shifts in microbial diversity but an increase in species involved in carbohydrate metabolism. Conclusions: After 12 weeks, the malnourished group showed higher post-intervention microbial richness and diversity than the healthy group, with differences in taxonomic and predicted functional profiles. Without a non-intervention control group, the microbiota differences observed during the 12-week aerobic exercise period can only be considered observational associations, not causal. Additionally, the high dropout rate (72.1%) limits the generalizability of the findings. Clinical trial registration: The Chinese Clinical Trial Registry on 19 October 2022 (ChiCTR2200064801). Full article

Background/Objectives: Nutritional strategies targeting redox and immune pathways may help to stabilize redox hemodynamics and support immune competence. Controlled physiological stress models allow examination of how nutrients influence dynamic antioxidant and inflammatory responses. Methods: In this randomized, double-blind, placebo-controlled trial (RCT), 39 healthy, moderately active men (supplement group: n = 20; placebo group: n = 19) received a yeast cell-derived formulation containing β-glucans and micronutrients or placebo for 8 weeks. Two standardized high-intensity interval training (HIIT) sessions (PRE/POST) transiently induced oxidative and inflammatory stress. Outcomes included reactive oxygen species (ROS; whole-blood EPR), total antioxidant capacity (FRAP), superoxide dismutase (SOD), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and upper respiratory tract infection (URTI) incidence and duration. Results: Prior to the intervention period, acute supplement intake resulted in a more pronounced reduction in ROS from 0′ to 60′ compared with placebo (−6.2%; p ≈ 0.14). After eight weeks, fasting FRAP increased only in the supplemented group (p < 0.01). Mixed-model repeated-measures ANOVA demonstrated significant time × group interactions for FRAP in both PRE and POST assessments, indicating differential temporal trajectories. The chronic FRAP increase correlated with the acute ROS reduction (p < 0.05; r² = 0.21). SOD activity was higher in the supplemented group at 60′ in the POST assessment (p < 0.05), and a significant time × group interaction was observed for SOD in POST. TNF-α decreased across the intervention in participants with elevated baseline values, whereas individuals with low initial concentrations showed no change. The supplemented group reported shorter URTI duration (−1.4 days; d = 0.34) and fewer prolonged episodes (>10 days: 5% vs. 15.8%), although these differences were not statistically significant. Conclusions: Eight weeks of supplementation with a yeast cell-derived formulation containing β-glucans and micronutrients was associated with differences in selected redox-related markers, including FRAP and SOD, without altering exercise-induced ROS dynamics. The observed patterns suggest subtle modifications in antioxidant-related response characteristics under standardized physiological stress. These findings warrant further investigation in larger and more heterogeneous cohorts, particularly in populations exposed to higher oxidative or inflammatory burden. Full article

Background: The progression of orthopedic diseases such as rheumatism and tendinopathies can be affected by metabolic conditions. Recent research suggests that changes in nutrition may affect symptom severity and recovery in orthopedic diseases. This study aims to explore whether the therapeutic efficacy of exercise therapy can be enhanced by adding nutritional advice in Achilles tendinopathy. Method: This 12-week randomized controlled pilot trial enrolled 16 adult patients (age 39.38 ± 9.46 years) suffering from chronic Achilles tendinopathy (≥3 months of symptoms, Victorian Institute of Sport Assessment—Achilles (VISA-A) scores below 80). Participants were randomly assigned to either the experimental group, receiving nutritional advice combined with home-based high-load tendon exercise training, or the control group, receiving exercise training alone. Outcomes included VISA-A scores, visual analog scale (VAS) pain assessments, body composition, and blood markers, analyzed through both intention-to-treat and per-protocol approaches. Results: Baseline characteristics showed no significant intergroup differences. From pre to post VISA-A scores increased from 58.06 ± 12.06 to 74.51 ± 17.81 points (p = 0.005) and VAS decreased from 3.19 ± 2.32 to 1.55 ± 1.66 points (p = 0.048) across all participants. Within-group analysis demonstrated a significant VISA-A improvement (63.13 ± 10.08 to 81.39 ± 13.13 points) (p = 0.013) in the experimental group only. The control group experienced a significant increase of 6.74 ± 12.26 mmHg in diastolic blood pressure (p = 0.046). Conclusions: The exercise intervention improved functional and pain outcomes in all participants, with better VISA-A outcomes in the experimental group. However, a clearly superior effect of the combined strategy compared with exercise alone could not be detected in this pilot study with a limited sample size. Full article

Background: Targeted training interventions, including neuromuscular warm-up protocols, eccentric resistance training, and dynamic stretching exercises, with limited and heterogeneous evidence on recovery strategies, have shown potential benefits for muscle performance and reductions in injury risk. Objective: To synthesize and structure contemporary evidence on exercise-based interventions spanning the pre-activity warm-up through post-activity recovery, emphasizing performance outcomes, injury-related effects, reported dose–response patterns, and implementation characteristics. Methods: This systematic review with structured qualitative synthesis was based on a systematic database search and eligibility screening process (n = 40 studies). Studies evaluating exercise-based interventions targeting injury prevention and/or performance in athletes were included. Data extraction included study design, population characteristics, intervention components, outcomes, and risk-of-bias assessments, which were summarized using comparative tables and descriptive analyses. Due to heterogeneity, results were synthesized qualitatively without meta-analysis. Results: Neuromuscular warm-ups (e.g., FIFA 11+) were frequently linked to reduced reported lower-extremity injury risk, alongside improvements in sprint, jump, and balance performance. Eccentric hamstring training was linked in several studies to lower reported hamstring injury rates and increased eccentric strength and fascicle length, while dynamic warm-ups may acutely improve sprint and jump performance. Evidence regarding recovery modalities was heterogeneous, supporting a cautious and individualized emphasis on sleep, nutrition, and hydration. However, heterogeneity in study designs, outcome measures, and populations limits the comparability and generalizability of the findings. Conclusions: Exercise-based interventions, including neuromuscular warm-ups, eccentric strengthening, dynamic stretching, and progressive load and recovery strategies, may support performance enhancement and injury-risk reduction in youth and adult athletes when appropriately implemented, although interpretation is limited by study heterogeneity. Full article

The aim of this study was to evaluate the impact of glutathione (GSH), applied in free form and in the form of microcapsules, on the release and nutritional properties of a functional post-exercise recovery snack. Five snack variants enriched with free GSH or microencapsulated GSH, applied using different incorporation strategies, were prepared and subjected to standardised in vitro digestion following the INFOGEST protocol. The study assessed GSH levels in the digesta, protein and fat digestibility, antioxidant capacity, and changes in fatty acid profiles after digestion. Snacks fortified with free GSH exhibited the highest immediate GSH levels in the digesta (up to 2390 ± 240 nmol/mL), whereas lower levels were observed for microencapsulated GSH (down to 1280 ± 132 nmol/mL), reflecting differences in release behaviour under in vitro digestion conditions. Products containing microencapsulated GSH showed a markedly higher post-digestion free amino acid content (1520 ± 100 mg/100 g) compared with those enriched with free GSH (820.3 ± 19 mg/100 g), indicating differences in the profile of protein digestion products. Antioxidant activity and phenolic content increased after digestion across all formulations, with no consistent differences between variants, while fat digestibility remained unchanged, although fatty acid profiles differed depending on the GSH application form. Overall, the results indicate that the form of GSH incorporation, including microencapsulation, influences its behaviour during in vitro digestion and affects the release and distribution of compounds within the food matrix. Full article

Biological differences between sexes—particularly due to fluctuating levels of 17β-estradiol and menstrual cycle dynamics—may influence exercise-induced reactive oxygen species (ROS) formation, inflammation and exercise performance. Despite these considerations, there is a lack of research exploring how estradiol and menstrual cycle phases may impact exercise performance, exercise-induced ROS formation and inflammation. This study aimed to examine whether estradiol concentration or menstrual cycle phase may be significantly associated with resistance circuit high-intensity interval training (HIIT) performance, as well as exercise-induced formation of ROS and Interleukin-6 (IL-6). A total of 30 young healthy female participants completed a single bout of resistance-based HIIT in a fasted state. Blood samples were collected at four time points: at baseline after overnight fasting, two hours after consumption of 0.5 L of water (pre-HIIT), immediately post exercise (post-HIIT) and after 15 min of recovery (15-post-HIIT). Additionally, participants attended six fasting baseline assessments scheduled across various menstrual cycle days. These sessions enabled the assessment of estradiol, ROS and IL-6 concentrations throughout the menstrual cycle without being confounded by nutritional factors. Neither baseline levels of ROS nor IL-6 differed significantly between menstrual cycle phases (luteal vs. follicular ROS: 0.013 µmol/min, p = 0.716; IL-6: 0.052, p = 0.679) menstruation status (yes vs. no ROS: −0.056 µmol/min, p = 0.259; IL-6: −0.302 pg/mL, p = 0.088) or 17β-estradiol concentrations (low (11–≤72.5 pg/mL) vs. high (>72.5–394 pg/mL) ROS: −0.038 µmol/min, p = 0.266; IL-6: +0.015 pg/mL, p = 0.906). On the resistance-circuit-HIIT intervention day, no significant differences in ROS or IL-6 were observed between estradiol concentrations (ROS: p = 0.477; IL-6: p = 0.249), menstrual cycle phase (ROS; p = 0.752; IL-6: p = 0.557) or menstruation status (ROS: p = 0.383; IL-6: p = 0.808) from baseline to pre-HIIT, post-HIIT or 15-post-HIIT. These findings should be interpreted with caution, as the menstrual cycle phases were assigned using a calendar-based approach without biochemical ovulation confirmation and the subgroup sizes were relatively small. These findings suggest that natural 17-beta-Estradiol fluctuations within the menstrual cycle, as well as differences in the menstrual cycle itself, may not substantially modulate ROS or IL-6 responses to acute resistance-based HIIT in young healthy female adults. Full article