Carbohydrate loading is an established sports nutrition strategy for endur- 16 ance exercise performance. We tested if carbohydrate loading could improve the performance of 17 elite soccer players under ecologically valid circumstances using Global Positioning System (GPS) data. Twenty-two adult Iran Premier league soccer players were divided into a carbohydrate-loading group (CLG) and Control group (CG). The carbohydrate loading group restricted carbohydrate intake for three days to 1.5 g/kg/d while increasing exercise intensity. From days four to seven, exercise intensity was decreased and carbohydrate intake was considerably increased up to 7.5 g/kg/d on the day of the match, during which performance was analyzed using GPS data. The control group performed the same exercise training but maintained their habitual carbohydrate intake of 5–6 g/kg/d. The data were analyzed using a univariate ANCOVA with baseline data from a pre-intervention match as the control variable. The carbohydrate loading team scored significantly higher on running distance, maximum speed and the number of top and repeated sprints; the carbohydrate loading group scored significantly lower on player load, metabolic power and running imbalance compared to the control team during their match. Our findings suggest carbohydrate loading enabled elite soccer players to achieve greater running outputs with greater metabolic efficiency and lower fatigue compared to their habitual diets.

Instead of being waste product of metabolism, lactate, has become a key metabolic and signaling molecule in both exercise physiology and tumor biology. Carcinogenic cells produce huge amounts of lactate through the Warburg effect, which is a hallmark of aggressive tumors, increasing acidity in the environment that can stimulates angiogenesis, immune evasion, and metastasis. Conversely, while exercise acutely elevates blood lactate concentration but it consider helpful for cancer patients. This paradox raises the following question: is exercise-induced lactate a friend or foe in cancer? This study reviews current evidence on the mechanistic, metabolic, immunological, and clinical impacts of exercise-induced lactate in cancer patients, highlighting the context-dependent effects that render lactate either beneficial or detrimental. Tumor-derived lactate seems to be pro-tumorigenic, driving immune suppression and disease progression, whereas short bursts of lactate from exercise can enhance anti-tumor immunity and metabolic reprogramming under the right conditions. Therefore, lactate’s impact on cancer is “all about the context”.

Spaceflight imposes unique physiological stressors that profoundly disrupt immune regulation, including impaired lymphocyte activation, latent viral reactivation, and chronic low-grade inflammation. While structured exercise is the cornerstone countermeasure for musculoskeletal and cardiovascular health, current protocols rarely integrate immune endpoints into their design. This review aims to synthesize current evidence on the immunological effects of exercise in spaceflight and propose a novel framework for immune-focused physical activity guidelines tailored to long-duration missions. Evidence indicates that exercise intensity and modality critically determine immune outcomes. Acute strenuous exercise may transiently suppress immunity via cortisol and reactive oxygen species pathways, whereas chronic moderate-to-vigorous training enhances immune surveillance, reduces systemic inflammation, and supports T-cell and NK-cell function. Exerkines such as IL-15, IL-7, and irisin emerge as central mediators of exercise-induced immunomodulation, with potential applications for spaceflight countermeasures. Incorporating immune health into exercise guidelines represents a necessary paradigm shift for astronaut care. A structured framework—emphasizing aerobic, resistance, and HIIT modalities; moderate-to-vigorous intensity; daily training; immune biomarker monitoring; and integration with nutrition and sleep—can enhance resilience against infection, viral reactivation, and cancer risk. Immune-focused countermeasures will be essential to safeguard astronaut health and ensure mission success on future deep-space expeditions.

Background: Physical exercise is strongly recommended for breast cancer survivors due to its beneficial effects on physical function, metabolic health, and quality of life. Lactate, traditionally considered a metabolic byproduct of glycolysis, is increasingly recognized as a signaling molecule involved in metabolic regulation and exercise adaptation. However, exercise-induced circulating lactate responses in breast cancer survivors remain poorly characterized. The aim of this systematic review and exploratory meta-analysis was to synthesize and critically appraise current evidence on exercise-induced circulating lactate responses in breast cancer survivors Methods: A systematic review and exploratory meta-analysis were conducted according to PRISMA guidelines and prospectively registered in PROSPERO (CRD42024504288). PubMed, Scopus, and Web of Science were searched to identify controlled trials investigating exercise-induced changes in circulating lactate concentrations in breast cancer survivors. Random-effects meta-analysis was performed using pooled mean differences. Results: Among 173 screened records, four studies met eligibility criteria for qualitative synthesis and three contributed to quantitative analysis. Pooled results demonstrated no statistically significant effect of exercise on circulating lactate concentrations (weighted mean difference: 0.03 mmol/L; 95% CI: −0.24 to 0.31; p = 0.81), with low heterogeneity (I² = 31.1%). Considerable variation was observed across exercise protocols, intervention duration, and lactate assessment timing. Conclusions: Exercise-induced circulating lactate responses in breast cancer survivors appear modest and inconsistently reported across available studies. Current evidence remains limited by small sample sizes and methodological heterogeneity. These findings provide a physiological overview of lactate responses to exercise in breast cancer survivorship and highlight the need for standardized exercise interventions and metabolic outcome assessment in future research.