Objective <p>Exercise is vital intervention to manage the complications due to hormonal transition among postmenopausal females. However, the exercise time is less explored area still very crucial for the precision of exercise benefit. Therefore, the objective of the present study was to find out the effect of diurnal variation in resistance training on cardiopulmonary functions among postmenopausal women.</p> Methodology <p>Eighty four postmenopausal females were randomly divided into three groups i.e. morning, evening, and control group. Pre-post study design was used. Single session of self-body weight resistance training was implemented as an intervention. Pulmonary functions i.e. Forced vital capacity (FVC), Forced expiratory volume at 1st second (FEV₁₎, and cardiac functions i.e. Heart rate (HR), systolic &amp; diastolic blood pressure (SBP and DBP) were taken as outcome measures.</p> Results <p>The results shows that there is no statistically significant change in pulmonary function both with and between group comparison as <i>p</i> &gt; 0.05. For cardiac functions, there is no statistically significant difference between groups as <i>p</i> &gt; 0.05. However, HR shows significant reduction in both morning and evening group (<i>p</i> = 0.0001). SBP shows significant reduction in evening group (<i>p</i> = .008). But, DBP shows statistical significant reduction in morning group (<i>p</i> = .001).</p> Conclusion <p>As there is no statistically significant difference between the groups, therefore, superiority of any time of exercise can not be established. Further studies of longer duration may be conducted to confirm the findings.</p> Trial registration <p>CTRI registration no. CTRI/2024/03/063728.</p>