Non-technical summary This is the first study, to our knowledge, to use cardiac MRI before and after intensive and closely supervised resistance and endurance exercise training in humans. There is a long held belief that these different forms of training induce 'concentric' and 'eccentric' adaptation of the heart, but this concept is based on echocardiographic assessments and cross-sectional comparison of different types of elite athletes. Our findings, using highly sensitive MRI methodology, suggest that concept may need to be reconsidered. This study is of fundamental importance to the understanding of the impact of exercise on human cardiac morphology and physiology.Abstract The principle that 'concentric' cardiac hypertrophy occurs in response to strength training, whilst 'eccentric' hypertrophy results from endurance exercise has been a fundamental tenet of exercise science. This notion is largely based on cross-sectional comparisons of athletes using echocardiography. In this study, young (27.4 ± 1.1 years) untrained subjects were randomly assigned to supervised, intensive, endurance (END, n = 10) or resistance (RES, n = 13) exercise and cardiac MRI scans and myocardial speckle tracking echocardiography were performed at baseline, after 6 months of training and after a subsequent 6 weeks of detraining. Aerobic fitness increased significantly in END (3.5 to 3.8 l min −1 , P < 0.05) but was unchanged in RES. Muscular strength significantly improved compared to baseline in both RES and END ( = 53.0 ± 1.1 versus 36.4 ± 4.5 kg, both P < 0.001) as did lean body mass (2.3 ± 0.4 kg, P < 0.001 versus 1.4 ± 0.6 kg P < 0.05). MRI derived left ventricular (LV) mass increased significantly following END (112.5 ± 7.3 to 121.8 ± 6.6 g, P < 0.01) but not RES, whilst training increased end-diastolic volume ( LVEDV, END: +9.0 ± 5.0 versus RES +3.1 ± 3.6 ml, P = 0.05). Interventricular wall thickness significantly increased with training in END (1.06 ± 0.0 to 1.14 ± 0.06, P < 0.05) but not RES. Longitudinal strain and strain rates did not change following exercise training. Detraining reduced aerobic fitness, LV mass and wall thickness in END (P < 0.05), whereas LVEDV remained elevated. This study is the first to use MRI to compare LV adaptation in response to intensive supervised endurance and resistance training. Our findings provide some support for the 'Morganroth hypothesis' , as it pertains to LV remodelling in response to endurance training, but cast some doubt over the proposal that remodelling occurs in response to resistance training.

Whilst the existence of a specific phenotype characterized as 'athlete's heart' is generally acknowledged, the question of whether athletes exhibit characteristic vascular adaptations has not been specifically addressed. To do so in this symposium, studies which have assessed the size, wall thickness and function of elastic, large muscular and smaller resistance arteries in athletes have been reviewed. Notwithstanding the caveats pertaining to cross-sectional comparisons between athletes and 'matched' control subjects, these studies reveal increased conduit artery size, including enlargement of epicardial arteries and those supplying skeletal muscle. Evidence that peak limb blood flow responses are enhanced in athletes further suggests that resistance arteries undergo increases in total cross-sectional area. Such increases can be localized to those arteries supplying active muscle leading to speculation, supported by exercise training studies in humans and animal and cellular data, that arterial enlargement is associated with repetitive episodic increases in arterial shear stress which elicit endothelium-mediated remodelling. Such structural remodelling at conduit and resistance artery level may play a role in accommodating the substantial increase in cardiac output apparent in endurance athletes; arterial pressure is not increased at rest or during exercise in athletes (versus control subjects). Arterial wall remodelling also occurs in athletes but, in contrast to the impact of shear stress on remodelling of arterial lumenal dimensions, the impact of endurance athletic status on wall thickness may be a systemic, rather than localized, phenomenon. Finally, the question of whether the arteries of athletes exhibit enhanced function is moot. Somewhat paradoxically, measures of conduit and resistance artery endothelial function may not be enhanced, compared with healthy control subjects. This may relate to the inherent difficulty of improving arterial function which is already normal, or the time course and transient nature of functional change. It may also relate to the impact of compensatory structural remodelling, as arterial lumen size and wall thickness both affect functional responsiveness. In summary, there is clear evidence for an impact of athletic status on arterial structure and function, at least with respect to the impact of endurance training. Arterial adaptation may, to some extent, emulate that evident in the hearts of endurance athletes, and it is tempting to speculate that similar mechanisms may be at play.

Beneficial effects of exercise training on the vasculature have been consistently reported in subjects with cardiovascular risk factors or disease, whereas studies in apparently healthy subjects have been less uniform. In this review, we examine evidence pertaining to the impact of exercise training on conduit and resistance vessel function and structure in asymptomatic subjects. Studies of arterial function in vivo have mainly focused on the endothelial nitric oxide dilator system, which has generally been shown to improve following training. Some evidence suggests that the magnitude of benefit depends upon the intensity or volume of training and the relative impact of exercise on upregulation of dilator pathways versus effects of inflammation and/or oxidation. Favourable effects of training on autonomic balance, baroreflex function and brainstem modulation of sympathetic control have been reported, but there is also evidence that basal vasoconstrictor tone increases as a result of training such that improvements in intrinsic vasodilator function and arterial remodelling are counterbalanced at rest. Studies of compliance suggest increases in both the arterial and the venous sides of the circulation, particularly in older subjects. In terms of mechanisms, shear stress appears to be a key signal to improvement in vascular function, whilst increases in pulse pressure and associated haemodynamics during bouts of exercise may transduce vascular adaptation, even in vascular beds which are distant from the active muscle. Different exercise modalities are associated with idiosyncratic patterns of blood flow and shear stress, and this may have some impact on the magnitude of exercise training effects on arterial function and remodelling. Other studies support the theory that that there may be different time course effects of training on specific vasodilator and constrictor pathways. A new era of understanding of the direct impacts of exercise and training on the vasculature is evolving, and future studies will benefit greatly from technological advances which allow direct characterization of arterial function and structure.

Objective The objectives of this cross-sectional qualitative study were to explore the perspectives of students enrolled in one physical therapist undergraduate education program in Australia about their experience with transitioning to full eLearning and student recommendations to improve the learning experience during the COVID-19 pandemic. Methods Seven focus groups with 28 undergraduate physical therapist students were conducted following the transitioning to full eLearning as a result of strict physical distancing measures. Focus group questions explored the students’ experiences of the transition from face-to-face to full eLearning approach and the students’ recommendations for improving future eLearning experiences. Data were analyzed using inductive thematic analysis. Results The 3 themes identified were: (1) students presenting heightened negative feelings such as anxiety, stress, and reduced motivation to study; (2) students continuing to value the face-to-face learning, as it provided social support and facilitated feedback from peers and tutors; (3) student recommendations for eLearning included having online lectures and supplementary videos but face-to-face practical classes and developing healthy learning habits such as scheduled times for studying, exercise, and other activities that regulate stress. Conclusions The transition to a full eLearning approach in an undergraduate physical therapist education program during the COVID-19 pandemic revealed that students had heightened negative emotions due to the pandemic. Students valued face-to-face practical classes to learn and receive social support from peers and tutors. Student recommendations to future eLearning suggested changes to curriculum development geared toward a greater blended approach to learning. Blended learning may include using online lectures instead of face-to-face lectures and online resources to supplement student learning of practical skills. Impact As higher education moves toward a more blended approach, lessons learned from this study can help educators design future physical therapist education programs. The findings can also assist programs in delivering a full eLearning approach as the COVID-19 pandemic continues.

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