The gut microbiome is known to play an important role in the day-to-day physiology and health of the human host. It is, therefore, not surprising that there is interest surrounding the gut microbiome and its potential to benefit athletic health and performance. This has, in part, been driven by the consideration that gut bacterial by-products (i.e. metabolic waste) could be harnessed by the host and utilised for a beneficial outcome. The concept of harnessing bacterial metabolites as beneficial health modulators has developed the theory of leveraging short-chain fatty acids (SCFAs) as novel supplements for enhancing athletic performance. This review discusses the current literature investigating SCFA administration in cellular, animal, and human models, with the aim of linking the demonstrated physiological/biochemical mechanisms to potential exercise/athletic benefit. In addition, practical implications and factors relating to SCFA-supplementation in athletic populations are considered. The literature demonstrates a tangible rationale that SCFAs can have a positive impact on human physiology to afford benefits to the athletic population. These advantages include the capacity to improve respiratory immunity to combat elevated levels/severity of upper respiratory tract infections often reported in athletes; the blunting of pro-inflammatory and pro-fibrotic pathways to aid in exercise recovery; and the role of SCFAs as usable energy sources and metabolism modulators to fuel exercise and improve performance and/or endurance capacity. However, there is currently minimal research completed in human participants and thus further investigations into the direct benefit of SCFAs in exercise performance and/or recovery-based studies are required.
Research in sport and exercise science (SES) is reliant on robust analyses of biomarker measurements to assist with the interpretation of physiological outcomes. Mass spectrometry (MS) is an analytical approach capable of highly sensitive, specific, precise, and accurate analyses of a range of biomolecules, many of which are of interest in SES including, but not limited to, endogenous metabolites, exogenously administered compounds (e.g. supplements), mineral ions, and circulating/tissue proteins. This annual review provides a summary of the applications of MS across studies investigating aspects related to sport or exercise in manuscripts published, or currently in press, in 2022. In total, 93 publications are included and categorized according to their methodologies including targeted analyses, metabolomics, lipidomics, proteomics, and isotope ratio/elemental MS. The advantageous analytical opportunities afforded by MS technologies are discussed across a selection of relevant articles. In addition, considerations for the future of MS in SES, including the need to improve the reporting of assay characteristics and validation data, are discussed, alongside the recommendation for selected current methods to be superseded by MS-based approaches where appropriate. The review identifies that a targeted, mostly quantitative, approach is the most commonly applied MS approach within SES, although there has also been a keen interest in the use of 'omics' to perform hypothesis-generating research studies. Nonetheless, MS is not commonplace in SES at this time, but its use to expand, and possibly improve, the analytical options should be continually considered to exploit the benefits of analytical chemistry in exercise/sports-based research. Overall, it is exciting to see the gradually increasing adoption of MS in SES and it is expected that the number, and quality, of MS-based assays in SES will increase over time, with the potential for 2023 to further establish this technique within the field.
Acetate, propionate, and butyrate are naturally-occurring short-chain fatty acids (SCFAs) derived from bacterial metabolism of dietary fibre and have been associated with numerous positive health outcomes. All three acids have been shown to offer unique physiological and metabolic effects and, therefore, could be targeted for co-ingestion as part of a nutritional/medicinal plan. However, a better understanding of the outcomes of supplementing in combination on circulating concentration profiles is necessary to confirm uptake efficacy. This study sought to investigate the acute circulating concentration profiles of acetate, propionate, and butyrate following oral supplementation. Three experimental trials were conducted including investigations to understand the impact of capsule coating on circulating concentration profiles, the effect of supplementation dose on uptake kinetics, and the outcome of a short, repeated, supplementation routine on circulating levels. Serum samples were analysed for SCFA content using a quantitative GC-MS assay. It was observed that an acid-resistant coated capsule caused a delayed and blunted blood concentration response, with the non-acid resistant trial displaying earlier and more intense peak serum concentrations. For dose comparison investigations, all SCFAs peaked within 60 min and returned to baseline concentrations by 120 min post-supplementation. A graded dose relationship was present for propionate and butyrate when considering the total circulating exposure across a 240 min monitoring period. In addition, a one-week, twice-daily, repeated supplementation protocol resulted in no changes in basal serum SCFA concentrations. Overall, these data indicate that acetate, propionate, and butyrate display relatively similar circulating concentration profiles following oral co-ingestion, adding knowledge to help inform supplementation strategies for future outcomes where acute elevation of circulating SCFAs is desired.