Acute hemodynamic and cardiovascular responses following resistance exercise to voluntary exhaustion. Effects of different loadings and exercise durations.

Background: The aim of this study was to compare the acute hemodynamic and cardiovascular responses of high load/low repetition resistance training (RT) to low load/high repetition RT.

Methods: Thirteen healthy men performed four sets of 4 repetition maximum (RM) and 20RM leg-extensions without breath-holding. The RT was conducted in a randomized order and with 48 hours between bouts. Non-invasive beat-to-beat systolic and diastolic blood-pressure (SBP/DBP) was measured on the finger, while non-invasive cardiac output (CO) was assessed beat-to-beat by impedance-cardiography.

Results: Mean±SD resting SBP/DBP and CO were 126±14/73±9 mmHg and 5.6±9 L min-1, respectively. Exercise SBP/DBP values increased to 154±22/99 ±18 and 203±33/126±19 mmHg following 4RM and 20RM RT, respectively (compared to rest, all; P<0.001), and 20RM SBP/DBP values were higher than 4RM values (both, P<0.001). The SBP increased from the first to the fourth set of exercise following the 20RM load (P<0.01), but not so for the 4RM load. Exercise SBP/DBP values following the 4th rep of 20RM exercise (154±18/91±14), was similar to the 4RM values, but different to the 20th rep of the 20 RM loading (both; P<0.001). CO increased to 10.8±2.6 and 13.9±2.2 L min-1, following 4RM and 20RM RT, respectively (compared to rest, both; P<0.001) and 20RM CO was higher than 4RM CO (P<0.01).

Conclusions: 20RM RT resulted in higher blood-pressure than 4RM RT when performed to voluntary exhaustion. Differences in hemodynamic responses seems to be related to training duration and not to difference in loading.