Geert Kleinnibbelink

Chapter 3 66 ABSTRACT Repeated ventricular exposure to alterations in workload may relate to subsequent cardiac remodelling. We examined whether baseline acute changes in right (RV) and left ventricular (LV) function relate to chronic cardiac adaptation to 12-week exercise training. Twenty-one healthy individuals performed 12-week high-intensity endurance running training under hypoxia (fraction of inspired oxygen: 14.5%). Resting transthoracic echocardiography was performed before and after the training programme to assess ventricular structure, function and mechanics (including strain-area/volume loops). In addition, we examined systolic cardiac function during recumbent exercise under hypoxia at baseline (heart rate of 110-120 bpm, ‘stress echocardiography’). Fifteen individuals completed training (22.0±2.4y, 10 male). Hypoxic exercise training increased RV size, including diameter and area (all p < 0.05).With exception of an increase in RV fractional area change (p=0.03), RV function did not change post-training (all p > 0.05). Regarding the RV strain-area loop, lower systolic and diastolic slopes were found post-training (p < 0.05). No adaptation in LV structure, function or mechanics were observed (all p > 0.05). To answer our primary aim, we found that a greater increase in RV fractional area change during baseline stress echocardiography (r=-0.67, P=0.01) inversely correlated with adaptation in RV basal diameter following 12-week training. In conclusion, 12-week high-intensity running hypoxic exercise training induced right-sided structural remodelling, which was, in part, related to baseline increase in RV fractional area change to acute exercise. These data suggest that acute cardiac responses to exercise may relate to subsequent RV remodelling after exercise training in healthy individuals.