This study sought to determine the optimal criteria and sampling interval to detect a V̇O₂ plateau at V̇O₂max in patients with metabolic syndrome. Twenty-three participants with criteria-defined metabolic syndrome underwent a maximal graded exercise test. Four different sampling intervals and three different V̇O₂ plateau criteria were analysed to determine the effect of each parameter on the incidence of V̇O₂ plateau at V̇O₂max. Seventeen tests were classified as maximal based on attainment of at least two out of three criteria. There was a significant (p < 0.05) effect of 15-breath (b) sampling interval on the incidence of V̇O₂ plateau at V̇O₂max across the ≤50 and ≤80 mL∙min⁻¹ conditions. Strength of association was established by the Cramer’s V statistic (φ_c); (≤50 mL∙min⁻¹ [φ_c = 0.592, p < 0.05], ≤80 mL∙min⁻¹ [φ_c = 0.383, p < 0.05], ≤150 mL∙min⁻¹ [φ_c = 0.246, p > 0.05]). When conducting maximal stress tests on patients with metabolic syndrome, a 15-b sampling interval and ≤50 mL∙min⁻¹ criteria should be implemented to increase the likelihood of detecting V̇O₂ plateau at V̇O₂max.