Anti-carcinogenic effects of exercise-conditioned human serum: evidence, relevance and opportunities.

Regular physical activity reduces the risk of several site-specific cancers in humans and suppresses tumour growth in animal models. The mechanisms through which exercise reduces tumour growth remain incompletely understood, but an intriguing and accumulating body of evidence suggests that the incubation of cancer cells with post-exercise serum can have powerful effects on key hallmarks of cancer cell behaviour in vitro. This suggests that exercise can impact tumour biology through direct changes in circulating proteins, RNA molecules and metabolites. Here, we provide a comprehensive narrative overview of what is known about the effects of exercise-conditioned sera on in vitro cancer cell behaviour. In doing so, we consider the key limitations of the current body of literature, both from the perspective of exercise physiology and cancer biology, and we discuss the potential in vivo physiological relevance of these findings. We propose key opportunities for future research in an area that has the potential to identify key anti-oncogenic protein targets and optimise physical activity recommendations for cancer prevention, treatment and survivorship.

Genes and Elite Marathon Running Performance: A Systematic Review.

Genetics has long been considered to associate with many exercise-related traits and sport performance phenotypes. A genetic basis for elite international marathon running performance exists due to the heritability of endurance-related traits. This has prompted a generation of genomic study to identify marathon success. The aim of this study was to systematically review the evidence of genes, and their polymorphisms, that may play a role in marathon running performance. A search strategy was implemented on systematic databases following PRISMA guidelines. Studies were case-control, cohort or genome-wide association designs and provided data on the genotypes associated with elite marathon athlete status and/or marathon running performance. The search identified 241 studies, from which, 14 studies were deemed suitable for inclusion. A total of 160 different polymorphisms in 27 genes were identified in 10,442 participants, of which 2,984 were marathon distance runners. The review identified a possible 16 single nucleotide polymorphisms (SNPs) in 14 genes associated with marathon running performance. While multiple genes and their polymorphisms have been associated with marathon running performance, predicting future marathon success based on genomic data is premature due to the lack of replicated studies. There is limited replication of genotype-phenotype associations and there is possible publication bias, thus, further studies are required to strengthen our understanding of the genes involved in marathon running. Future research utilising genome-wide technologies in large cohorts is required to elucidate the multiple genetic factors that govern complex endurance-related traits and the impact of epigenetics should be considered.