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Introduction: Blood flow restriction exercise has proven to be an effective training method to promote neuromuscular adaptations, however, a consensus about the effect on other physiological and safety variables, such as cardiovascular responses, has yet to be reached. Purpose: The aim of this study was to compare the acute cardiovascular responses during and after three different resistance training protocols. Material & methods: Fifty-two participants (27.3±7 years; 177.6±11 cm; 72.2±13.7 kg) were randomly allocated into three groups: low-intensity exercise without (LI, n=13) and with blood flow restriction (LI-BFR, n=24), and high-intensity exercise (HI, n=15). Participants from LI and LI-BFR groups performed four sets (1x30 + 3x15 reps) at 30% 1RM, while HI group performed four sets (1x30 with 30% 1RM + 3x10 reps with 75% 1RM) of dominant-side plantar flexion exercise. For LI-BFR group, a cuff was placed under popliteal region and inflated at 30% of the individual´s occlusion pressure (47.6 ± 19.8 mmHg). Results: Blood pressure (BP), heart rate (HR) and oxygen saturation (SpO2) were assessed at baseline, after each set and post-exercise. HR increases significantly during exercise across all protocols, with greater increases for HI group after 4th set (p<0.001; G=1.072) but without differences between groups. HI and LI-BFR protocols showed higher significant post-exercise hypotension and greater reduction in MAP (p<0.05) than LI group. RPP during exercise was different from HI to LI and LI-BFR (p<0.05). HI protocol reduced SpO2 during all sets of exercise (p<0.05). Conclusions: The results of this study indicate that LI-BFR promotes similar hypotensive response to HI, with equal or lower cardiovascular responses during exercise than traditional resistance training.

The Achilles tendon is one of the strongest and thickest tendons of the human body. Several studies have reported an immediate decrease in Achilles tendon thickness after a single bout of resistance training. However, the effects of blood flow restriction training on Achilles tendon thickness have not been investigated. The purpose of this study was to investigate the acute effects of different regimens of resistance training on Achilles tendon thickness. Fiftytwo participants (27.3 ± 7 years; 177.6 ± 11 cm; 72.2 ± 13.7 kg) were randomly allocated into one of the three groups: low-intensity exercise without (LI, n = 13) and with blood flow restriction (LI-BFR, n = 24), and high-intensity exercise (HI, n = 15). Participants from LI and LI-BFR groups performed four sets (1 x 30 + 3 x 15 reps) at 30% 1RM, while the HI group performed four sets (1 x 30 with 30% 1RM + 3 x 10 reps with 75% 1RM). All groups performed a plantar flexion exercise. For the LI-BFR group, a blood pressure cuff was placed on the dominant calf and inflated at 30% of the individual´s occlusion pressure (47.6 ± 19.8 mmHg). Sonographic images of Achilles tendon thickness were taken at pre, immediately after, 60 min and 24 h following acute bouts of exercise. Achilles tendon thickness was significantly reduced immediately after, 60 min and 24 h post-LI-BFR exercise (pre: 4.4 ± 0.4 mm vs. IA: 3.8 ± 0.4 mm vs. 60 min: 3.7 ± 0.3 mm vs. 24 h: 4.1 ± 0.3 mm; p < 0.001), whereas Achilles tendon thickness was unchanged for HI and LI groups (p > 0.05). These results suggest that blood flow restriction training may be an effective strategy to stimulate a positive response in Achilles tendon thickness.

The Achilles tendon is one of the strongest and thickest tendons of the human body. Several studies have reported an immediate decrease in Achilles tendon thickness after a single bout of resistance training. However, the effects of blood flow restriction training on Achilles tendon thickness have not been investigated. The purpose of this study was to investigate the acute effects of different regimens of resistance training on Achilles tendon thickness. Fiftytwo participants (27.3 ± 7 years; 177.6 ± 11 cm; 72.2 ± 13.7 kg) were randomly allocated into one of the three groups: low-intensity exercise without (LI, n = 13) and with blood flow restriction (LI-BFR, n = 24), and high-intensity exercise (HI, n = 15). Participants from LI and LI-BFR groups performed four sets (1 x 30 + 3 x 15 reps) at 30% 1RM, while the HI group performed four sets (1 x 30 with 30% 1RM + 3 x 10 reps with 75% 1RM). All groups performed a plantar flexion exercise. For the LI-BFR group, a blood pressure cuff was placed on the dominant calf and inflated at 30% of the individual´s occlusion pressure (47.6 ± 19.8 mmHg). Sonographic images of Achilles tendon thickness were taken at pre, immediately after, 60 min and 24 h following acute bouts of exercise. Achilles tendon thickness was significantly reduced immediately after, 60 min and 24 h post-LI-BFR exercise (pre: 4.4 ± 0.4 mm vs. IA: 3.8 ± 0.4 mm vs. 60 min: 3.7 ± 0.3 mm vs. 24 h: 4.1 ± 0.3 mm; p < 0.001), whereas Achilles tendon thickness was unchanged for HI and LI groups (p > 0.05). These results suggest that blood flow restriction training may be an effective strategy to stimulate a positive response in Achilles tendon thickness.