George and dad, just back from different parkruns, discuss fuelling for marathons. Whilst getting 'more energy' into muscles may seem critical, there is a potentially embarrassing downside. With up to 50% of runners suffering with 'issues' on race day or in long runs, fuelling is also potentially a limiting factor (https://pubmed.ncbi.nlm.nih.gov/3167507/). Gut transit times, of course, get a mention!