Commentary: What do comparative studies on oxidative stress biomarkers actually tell us?

Oxidative stress is widely invoked in comparative physiology to explain changes in physical performance, fitness proxies, and stress tolerance. However, such inference is frequently based on limited biomarker panels, often malondialdehyde/thiobarbituric acid reactive substances and one or two antioxidant enzyme activities (e.g., superoxide dismutase and catalase) measured simultaneously. This practice can conflate adaptive redox signaling with injurious redox imbalance, obscure the roles of thiol redox systems and energetic constraints, and contribute to inconsistent conclusions across taxa, tissues, and stressors. Building on contemporary definitions that emphasize disruption of redox signaling or control and/or molecular damage, this Commentary proposes a pragmatic redox-matrix-based framework for interpreting oxidative-state datasets and recommends a minimal, experimentally accessible reporting package. We argue that combining at least two classes of oxidation products with a thiol/disulfide redox readout, an energetic/nicotinamide adenine dinucleotide phosphate context marker, and a basic time course can substantially strengthen mechanistic interpretation while remaining feasible for most laboratories.