Research perspective · 17 October 2026
Endurance exercise, red blood cells and recovery
The demands of a long race reach beyond the calorie counter. What can red-cell research tell us about recovery?
What the research found
Nemkov and colleagues sampled athletes before and after 40-km and 171-km trail races. They identified inflammatory and oxidative changes in red blood cells, including lipid and protein alterations associated with reduced deformability. The longer event produced more pronounced molecular disturbances. [1]
This was a before-and-after investigation, not a randomised fuelling trial. It does not establish that inadequate intake caused the changes, that extra carbohydrate prevents them, or that ordinary running accelerates whole-body ageing. [1]
Why EPK should look beyond expenditure
EPK stands for Energy per Kilogram. Its performance pathway is intended to support the demands of activity, but a daily calorie estimate cannot tell us whether a particular athlete has recovered. I would use this study to motivate better recovery measurements, not to calculate an extra allowance from the blood results.
The distinction matters in practice. Completing a demanding session and tolerating repeated sessions are different questions. A research programme should allow a fuelling strategy to be evaluated alongside workload, rather than assume that matching an estimated calorie number resolves every consequence of training.
What would a fuelling study need?
A prospective comparison could test a defined nutrition strategy while recording intake, carbohydrate timing, training load, sleep and recovery. Blood sampling would need consistent timing and hydration assessment. Follow-up would help distinguish an immediate response from a persistent change. These are proposed design features, not interventions tested by this paper.
The comparison should not deliberately expose athletes to harmful restriction. An appropriate study could compare the EPK approach with established sports-nutrition support, with a prespecified primary outcome and monitoring. An improvement in a laboratory marker would need to be interpreted alongside performance, symptoms and tolerability.
Avoiding a misleading message about exercise
The useful message is to investigate the conditions under which athletes recover well. It would be misleading to use an extreme endurance event as evidence that all activity is damaging, or to promise that a fixed surplus prevents the effects observed here. This study did not test EPK’s approximate 15% performance allowance.
Likewise, the presence of oxidised lipids does not identify a dietary fat intake that caused them. Connecting this work with lipid-metabolism research is useful for generating questions, but it cannot replace a direct dietary comparison.
Connections to the working papers
EPK–004 concerns functional capacity and recovery; EPK–005 asks about inadequate energy availability; EPK–007 proposes questions about resources and responses to stress. The connection to the latter two is hypothesis-generating. The companion Fuel Selection, Tissue Function and Recovery paper is linked below. These are related discussions, not claims that the race study validated EPK.
Related research
Research and guidance
Explore more studies in the research library.
- Nemkov T, et al. Long-distance trail running induces inflammation-associated protein, lipid, and purine oxidation in red blood cells. Blood Red Cells & Iron. 2026;2:100055.
- Author manuscript in PubMed Central.
- Companion working paper: Fuel Selection, Tissue Function and Recovery (2026), v1.0.
- Research-library entry: endurance and red-cell recovery.
Related working papers
Read the relevant PDFs: EPK–001 to 007 are the revised version 1.2 papers; EPK–008 to 010 are version 1.0 supplements. Earlier PDFs and DOI records remain on the paper archive.