The weeks before a marathon are when small problems become big ones. Here is what to check in your blood, and when, so nothing derails race day.
Marathon training pushes your body to its limits, and the final build is exactly when small issues turn into race-day problems. A well-timed blood check gives you the chance to fix things while you still can, rather than discovering them at kilometre 32.
The sweet spot is six to eight weeks out from your goal race. That leaves time to act on anything you find through nutrition or a conversation with your doctor, while still reflecting the demands of peak training. Testing in race week is too late to change the outcome.
High mileage drives iron down through sweat and foot-strike impact, and low iron is one of the most common reasons a marathon build falls apart. Checking ferritin and iron during your heaviest weeks is the single most valuable pre-race marker for most runners.
Markers like hs-CRP and creatine kinase reflect how much stress your body is carrying and how well it is recovering. Reading them late in your build helps you judge whether you are absorbing the training or quietly digging a hole that the taper will not fully fix.
Vitamin D, B12, and blood sugar markers all affect how steadily you produce energy over a long effort. Topping up a low result in the weeks before a race can make a real difference to how strong you feel in the closing stages.
Walking to the start line knowing your numbers are in a good place removes one of the biggest unknowns in marathon racing. SuperRun's Endura and Elite panels are built for runners in serious training, so a single test before your peak weeks covers the markers that matter most.
This article is general information for runners and is not medical advice, a diagnosis, or a treatment plan. Always discuss your results and any health concerns with your GP or a qualified health professional.
SuperRun is blood testing built for runners. The Endura panel tracks 50+ biomarkers built for runners in serious training, scored against athlete performance zones. No GP referral needed, with 4,000+ collection centres across Australia.
