Intensity-dependent cardiopulmonary response during and after strength training

Whereas cardiopulmonary responses are well understood in endurance training, they are rarely described in strength training. This cross-over study examined acute cardiopulmonary responses in strength training. Fourteen healthy male strength training-experienced participants (age 24.5 +/- 2.9 years; BMI 24.1 +/- 2.0 kg/m(2)) were randomly assigned into three strength training sessions (three sets of ten repetitions) with different intensities (50%, 62,5%, and 75% of the 3-Repetition Maximum) of squats in a smith machine. Cardiopulmonary (impedance cardiography, ergo-spirometry) responses were continuously monitored. During exercise period, heart rate (HR 143 +/- 16 vs. 132 +/- 15 vs. 129 +/- 18 bpm, respectively; p < 0.01; eta(2)(p) 0.54) and cardiac output (CO: 16.7 +/- 3.7 vs. 14.3 +/- 2.5 vs. 13.6 +/- 2.4 l/min, respectively; p < 0.01; eta(2)(p) 0.56) were higher at 75% of 3-RM compared to those at the other intensities. We noted similar stroke volume (SV: p = 0.08; eta(2)(p) 0.18) and end-diastolic volume (EDV: p = 0.49). Ventilation (V-E) was higher at 75% compared to 62.5% and 50% (44.0 +/- 8.0 vs. 39.6 +/- 10.4 vs. 37.6 +/- 7.7 l/min, respectively; p < 0.01; eta(2)(p) 0.56). Respiration rate (RR; p = .16; eta(2)(p) 0.13), tidal volume (VT: p = 0.41; eta(2)(p) 0.07) and oxygen uptake (VO2: p = 0.11; eta(2)(p) 0.16) did not differ between intensities. High systolic and diastolic blood pressure were evident (62.5% 3-RM 197 +/- 22.4/108.8 +/- 13.4 mmHG). During the post-exercise period (60 s), SV, CO, V-E, VO2, and VCO2 were higher (p < 0.01) than during the exercise period, and the pulmonary parameters differed markedly between intensities (V-E p < 0.01; RR p < 0.01; VT p = 0.02; VO2 p < 0.01; VCO2 p < 0.01). Despite the differences in strength training intensity, the cardiopulmonary response reveals significant differences predominantly during the post-exercise period. Intensity-induced breath holding induces high blood pressure peaks and cardiopulmonary recovery effects after exercise.

Automated summary

This study examined acute cardiopulmonary responses in strength training. The results showed that at 75% of the 3-RM intensity, heart rate and cardiac output were higher compared to other intensities. During the post-exercise period, there were significant differences in respiratory parameters. The findings suggest that strength training intensity affects cardiopulmonary responses and post-exercise recovery effects.