240 Short-Term High-Intensity Interval Training and Continuous Moderate-Intensity Training Improve Maximal Aerobic Power and Diastolic Filling During Exercise

Abstract

BackgroundA limited number of studies have assessed the influence of short-term continuous moderate-intensity training (CMT) on cardiovascular function. Yet, the effects of high-intensity interval training (HIT) on cardiac morphology and function have not been investigated during the early stages of training. Therefore, the purpose of our study was to examine the effects of short-term HIT and CMT on cardiac function at rest and during exercise in young, healthy men.MethodsSixteen previously untrained men (mean age of 25.1 ± 4.1 years) were randomly assigned to HIT and CMT (n = 8 each) and assessed before and after six training sessions over a 12-day training period. HIT consisted of 8-12 intervals of cycling for 60 seconds at 95-100% of pre-training maximal aerobic power (VO2max), interspersed by 75 seconds of cycling at 10% pre-training VO2max. CMT involved 90-120 minutes of cycling at 65% pre-training VO2max. Left ventricular (LV) function was determined at rest and during submaximal exercise (HR ∼105 bpm) using two-dimensional and Doppler echocardiography (ECHO).ResultsHIT and CMT resulted in increased calculated plasma volume (PV) of 10.8% and 9.7%, respectively. PV expansion was accompanied by improved VO2max in HIT (from 39.5 ± 7.1 to 43.9 ± 5.5 ml/kg/min; P < 0.001) and CMT (from 39.9 ± 5.9 to 41.7 ± 5.3 ml/kg/min; P = 0.022). Resting LV function was not altered. However, increased exercise stroke volume (HIT vs. CMT; P < 0.001 vs. P = 0.034) and cardiac output (HIT vs. CMT; P < 0.001 vs. P = 0.034) were observed, secondary to increases in end-diastolic volume (HIT vs. CMT; P < 0.001 vs. P = 0.037). Numerous Doppler ECHO and speckle tracking indices of diastolic function during exercise were similarly enhanced during exercise in both training groups.ConclusionShort-term HIT and CMT elicit rapid increases in VO2max and LV filling without global changes in cardiac performance or morphology at rest. These enhancements were similar in both groups, despite HIT comprising only 25% of the total training work and time as CMT. BackgroundA limited number of studies have assessed the influence of short-term continuous moderate-intensity training (CMT) on cardiovascular function. Yet, the effects of high-intensity interval training (HIT) on cardiac morphology and function have not been investigated during the early stages of training. Therefore, the purpose of our study was to examine the effects of short-term HIT and CMT on cardiac function at rest and during exercise in young, healthy men. A limited number of studies have assessed the influence of short-term continuous moderate-intensity training (CMT) on cardiovascular function. Yet, the effects of high-intensity interval training (HIT) on cardiac morphology and function have not been investigated during the early stages of training. Therefore, the purpose of our study was to examine the effects of short-term HIT and CMT on cardiac function at rest and during exercise in young, healthy men. MethodsSixteen previously untrained men (mean age of 25.1 ± 4.1 years) were randomly assigned to HIT and CMT (n = 8 each) and assessed before and after six training sessions over a 12-day training period. HIT consisted of 8-12 intervals of cycling for 60 seconds at 95-100% of pre-training maximal aerobic power (VO2max), interspersed by 75 seconds of cycling at 10% pre-training VO2max. CMT involved 90-120 minutes of cycling at 65% pre-training VO2max. Left ventricular (LV) function was determined at rest and during submaximal exercise (HR ∼105 bpm) using two-dimensional and Doppler echocardiography (ECHO). Sixteen previously untrained men (mean age of 25.1 ± 4.1 years) were randomly assigned to HIT and CMT (n = 8 each) and assessed before and after six training sessions over a 12-day training period. HIT consisted of 8-12 intervals of cycling for 60 seconds at 95-100% of pre-training maximal aerobic power (VO2max), interspersed by 75 seconds of cycling at 10% pre-training VO2max. CMT involved 90-120 minutes of cycling at 65% pre-training VO2max. Left ventricular (LV) function was determined at rest and during submaximal exercise (HR ∼105 bpm) using two-dimensional and Doppler echocardiography (ECHO). ResultsHIT and CMT resulted in increased calculated plasma volume (PV) of 10.8% and 9.7%, respectively. PV expansion was accompanied by improved VO2max in HIT (from 39.5 ± 7.1 to 43.9 ± 5.5 ml/kg/min; P < 0.001) and CMT (from 39.9 ± 5.9 to 41.7 ± 5.3 ml/kg/min; P = 0.022). Resting LV function was not altered. However, increased exercise stroke volume (HIT vs. CMT; P < 0.001 vs. P = 0.034) and cardiac output (HIT vs. CMT; P < 0.001 vs. P = 0.034) were observed, secondary to increases in end-diastolic volume (HIT vs. CMT; P < 0.001 vs. P = 0.037). Numerous Doppler ECHO and speckle tracking indices of diastolic function during exercise were similarly enhanced during exercise in both training groups. HIT and CMT resulted in increased calculated plasma volume (PV) of 10.8% and 9.7%, respectively. PV expansion was accompanied by improved VO2max in HIT (from 39.5 ± 7.1 to 43.9 ± 5.5 ml/kg/min; P < 0.001) and CMT (from 39.9 ± 5.9 to 41.7 ± 5.3 ml/kg/min; P = 0.022). Resting LV function was not altered. However, increased exercise stroke volume (HIT vs. CMT; P < 0.001 vs. P = 0.034) and cardiac output (HIT vs. CMT; P < 0.001 vs. P = 0.034) were observed, secondary to increases in end-diastolic volume (HIT vs. CMT; P < 0.001 vs. P = 0.037). Numerous Doppler ECHO and speckle tracking indices of diastolic function during exercise were similarly enhanced during exercise in both training groups. ConclusionShort-term HIT and CMT elicit rapid increases in VO2max and LV filling without global changes in cardiac performance or morphology at rest. These enhancements were similar in both groups, despite HIT comprising only 25% of the total training work and time as CMT. Short-term HIT and CMT elicit rapid increases in VO2max and LV filling without global changes in cardiac performance or morphology at rest. These enhancements were similar in both groups, despite HIT comprising only 25% of the total training work and time as CMT.