Purpose <p>To examine the relationship between ventilatory thresholds relative to peak oxygen uptake with peak oxygen uptake, waist circumference, and body mass index in males with class I obesity and normal-weight males. A secondary aim was to assess the agreement between physiological intensity zones determined by ventilatory thresholds and exercise intensity recommendations.</p> Methods <p>Seventeen male adults with class I obesity and 17 normal-weight male adults were recruited. After assessing waist circumference, body weight, height, and resting heart rate, participants underwent an incremental exercise test to exhaustion to determine peak oxygen uptake, maximal heart rate, and ventilatory thresholds I and II. Group comparisons and correlation analyses between ventilatory thresholds relative to peak oxygen uptake and peak oxygen uptake, waist circumference, and body mass index were performed.</p> Results <p>In normal-weight males but not in individuals with obesity class I, ventilatory threshold I and ventilatory threshold II were positively correlated with peak oxygen uptake (Rho = 0.54 and Rho = 0.59, respectively). Ventilatory threshold II was inversely associated with waist circumference only in normal-weight males (Rho = −0.70), but not in the group with obesity. In the obese and normal-weight groups, less than 50% of participants met the exercise intensity recommendations for moderate and heavy-intensity zones based on their physiological thresholds.</p> Conclusions <p>Ventilatory thresholds exhibit different relationships with peak oxygen uptake in normal-weight individuals compared to those with class I obesity, suggesting that distinct factors may influence ventilatory thresholds across these populations. Given the low percentage of individuals whose physiological intensity zones align with exercise recommendations, these findings highlight the importance of individual physiological threshold assessments for exercise prescription.</p>