Outside factors that muddy whether the studied intervention really caused the result.
A confounder is a variable that is associated with both the exposure (or intervention) and the outcome, distorting the apparent relationship between them and creating a risk of misattributing cause and effect. Common examples in sports-medicine research include training load, age, prior injury history, and concurrent treatments that weren't controlled for. Well-designed studies address confounding through randomisation, matching, or statistical adjustment, but residual or unmeasured confounding can still bias findings, so appraise study design before accepting a causal claim.
This guide was auto-drafted and is pending editorial review.