Exercise-induced increases in blood pressure (BP) are partially attributable to the activation of sensory afferents within skeletal muscle (muscle metaboreceptors). However, whether the pressor response elicited by the muscle metaboreceptors is attributable to an elevation in cardiac output (CO) or a sympathetically mediated increase in peripheral vascular resistance (TPR) remains controversial. The equivocal findings of previous studies in this area may be in part related to differences in the mode of muscle metaboreceptor activation (i.e. during or following exercise). To examine this, 10 healthy men (age 20±0.2 years, weight 78±3 kg, height 181±2 cm; mean ± SE) were studied. Participants performed 4 handgrip trials, all at 25% maximum voluntary contraction. Trial 1 consisted of isometric handgrip (IHG, 3 min) followed by post-exercise ischaemia (PEI, 3 min) to activate muscle metaboreceptors in isolation. Trial 2 consisted of IHG (3 min) followed by a recovery period under free-flow conditions (3 min). Trial 3 consisted of ischaemic rhythmic handgrip (RHG; 1 s contraction, 1 s relaxation) to volitional fatigue, to enhance muscle metaboreceptor activation during exercise. Trial 4 consisted of RHG under free-flow conditions and matched in duration to the ischaemic RHG bout in trial 3. Heart rate (HR, ECG) and beat-to-beat blood pressure (BP, Portapress) were continuously monitored. Doppler echocardiography was used to measure stroke volume (SV). CO (HR×SV) and TPR (mean BP/CO) were calculated. Statistical analyses were performed using two-way repeated-measures ANOVA with Student-Newman-Keuls post hoc tests. Both IHG trials elicited similar increases in mean BP (+29±2 and +30±3 mmHg, P<0.05 vs. baseline), CO and HR (+19±3 and +19±3 bpm, P<0.05 vs. baseline) in trials 1 and 2, while TPR and SV were unchanged. Mean BP (+22±3 mmHg, P<0.05 vs. baseline) and TPR were significantly elevated during isolated muscle metaboreceptor activation with PEI following IHG, while HR, SV and CO were at baseline levels. Increases in mean BP (+37±4 vs. +11±2 mmHg, P<0.05 ischaemic vs. free-flow RHG), CO and HR (+21±5 vs. +7±2 bpm, P<0.05 ischaemic vs. free-flow RHG) were augmented with enhanced muscle metaboreceptor activation during ischaemic RHG (trial 3), compared with RHG under free-flow conditions (trial 4). SV and TPR were unchanged from baseline during RHG under ischaemic or free-flow conditions (P>0.05). These data suggest that the elevated mean BP resulting from isolated activation of muscle metaboreceptors (PEI) are secondary to increases in TPR, whereas elevations in mean BP during enhanced muscle metaboreceptor activation (ischaemic exercise) can be explained by HR mediated increases in CO. Taken together, these findings support the notion that the mode of muscle metaboreceptor activation (i.e. during vs. post exercise) is an important determinant of the resultant haemodynamic response.