Unraveling the complexity of the impact of physical exercise on male reproductive functions: a review of both sides of a coin

Sweet Drinks, Sour Consequences: The Impact of Sugar-Sweetened Beverages on Sperm Health, a Narrative Review

Introduction: The rising global consumption of sugar-sweetened beverages (SSBs) has paralleled a concerning decline in sperm quality, raising concern about potential dietary impacts on male fertility. Sperm health parameters, including count, motility, and morphology, are critical indicators of reproductive potential and may be adversely affected by excessive sugar intake. This narrative review consolidates the current evidence on the association between SSB consumption and sperm health, highlighting potential biological mechanisms. Methods: A targeted literature search across PubMed, Scopus, and Google Scholar was conducted, utilising keywords "sugar-sweetened beverages", "sperm health", and related terms. A total of 11 eligible observational and cohort studies were selected. Studies focusing solely on animal models or unrelated dietary factors were excluded. Results: The primary research consistently reports a negative association between high SSB consumption and sperm parameters, including reduced count and motility, and increased DNA fragmentation. Potential mechanisms include oxidative stress, hormonal dysregulation, and metabolic dysfunction linked to obesity and insulin resistance. However, variability in study design, exposure assessment, and population demographics limits generalisability of the results. Conclusions: The current evidence suggests that regular SSB consumption adversely affects male reproductive health through oxidative damage and hormonal imbalances. These findings underscore the importance of public health strategies to reduce SSB intake, especially among young men of reproductive age. Further longitudinal studies with standardised methodologies, particularly in underrepresented populations such as Asian cohorts, are necessary to establish causal relationships and guide clinical recommendations.

Protective Role of Physical Activity and Antioxidant Systems During Spermatogenesis

Oxidative stress is a significant factor that contributes to male infertility and sperm dysfunction. In this condition, an increase in ROS production exceeds the body's antioxidant defenses, resulting in a decline in spermatozoa quality and fertilizing capacity. Furthermore, excessive ROS production has been linked to the promotion of genomic damage, lipid peroxidation, inflammation, altered enzyme activity, and ultimately, irreversible alterations, cell death, and a decline in seminal parameters associated with male infertility. It is established that physical activity (PA), acting on inflammatory parameters and improving antioxidant defense, can alleviate the negative effects caused by free radicals, offering numerous health benefits and positively influencing sperm quality. The objective of this review is to highlight the mechanisms of ROS production, the physiological and pathophysiological roles of ROS in relation to the male reproductive system, and recent knowledge on the impact of some protocols of PA on these systems and the molecular mechanisms involved.

The microRNA-mediated apoptotic signaling axis in male reproduction: a possible and targetable culprit in male infertility

Recently, infertility has emerged as a significant and prevalent public health concern warranting considerable attention. Apoptosis, recognized as programmed cell death, constitutes a crucial process essential for the maintenance of normal spermatogenesis. Multiple investigations have illustrated that the dysregulated apoptosis of reproductive cells, encompassing spermatogonial stem cells, Sertoli cells, and Leydig cells, serves as a causative factor in male infertility. MicroRNAs represent a class of small RNA molecules that exert negative regulatory control over gene expression using direct interaction with messenger RNA transcripts. Previous studies have established that aberrant expression of miRNAs induces apoptosis in reproductive tissues, correlating with reproductive dysfunctions and infertility. In this review, we offer a comprehensive overview of miRNAs and their respective target genes implicated in the apoptotic process. As well, miRNAs are involved in multiple apoptotic signaling pathways, namely the PI3K/AKT, NOTCH, Wnt/β-catenin, and mTOR signaling cascades, exerting both negative and positive effects. We additionally elucidate the significant functions played by lncRNAs and circular RNAs as competing endogenous RNAs in the process of apoptosis within reproductive cells. We further illustrate that external factors, including silica nanoparticles, Cyclosporine A, and smoking, induce dysregulation of miRNAs, resulting in apoptosis within reproductive cells and subsequent male reproductive toxicity. Further, we discuss the implication of heat stress, hypoxia, and diabetes in reproductive cell apoptosis induced by miRNA dysregulation in male infertility. Finally, we demonstrate that the modulation of miRNAs via traditional and novel medicine could protect reproductive cells from apoptosis and be implemented as a therapeutic approach in male infertility.