Acute Autonomic and Perceptual Responses to Resistance Training Performed With and Without Blood Flow Restriction

Objectives: This study aimed to compare the acute effects of high-intensity resistance training (HIRT), low-intensity resistance training (LIRT), and low-intensity resistance training with blood flow restriction (LIRT-BFR) on heart rate variability (HRV), rating of perceived exertion (RPE), total load (kg), and number of repetitions in young trained men. Methods: Thirteen volunteers (21.5 ± 1.6 years; 178.2 ± 8.0 cm; 75.7 ± 8.0 kg) performed three training sessions with six upper- and lower-limb exercises in repetition-to-failure mode. HIRT was performed at 70% 1RM, four sets and 90 s of rest; LIRT at 30% 1RM, four sets and 30 s of rest; and LIRT-BFR at 30% 1RM, four sets, 30 s of rest, and cuff pressure at 80 mmHg. The rest interval between training sessions was 72 h. Results: Total load was higher during LIRT compared with LIRT-BFR (p < 0.05), with no significant difference compared with HIRT (p > 0.05). The number of repetitions was greater in LIRT than in HIRT (p < 0.05), with no significant difference compared with LIRT-BFR (p > 0.05). RPE was lower in LIRT compared with HIRT and LIRT-BFR (p < 0.05). Time-domain parameters SDNN significantly decreased across all protocols (p < 0.001), whereas RMSSD showed no differences. Frequency-domain components (LFnu, HFnu, and LF/HF) showed no significant differences. Conclusions: LIRT elicited lower perceived exertion compared with HIRT and LIRT-BFR and higher repetition performance, whereas LIRT-BFR, despite showing similar autonomic responses, produced greater perceptual stress, resembling that of HIRT.