Exercise for Cardiovascular Disease Prevention and Treatment From Molecular to Clinical, Part 1

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1 Introduction

Exercise affects virtually every organ and contributes to many cardiovascular health

benefits. Current concept of exercise was further extended as an active therapy

which can prevent or enhance various chronic pathological conditions including

cardiovascular diseases. Thus researchers are trying to understand the benefits of

exercise in the cardiovascular system, as well as the underlying molecular biologi-

cal mechanisms behind it. Literature review shows exercise as a simple and low-

cost lifestyle intervention and has shown its feasibility, desirability, and practicality.

However, there is a need of using different animals to study exercise due to concerns

such as research ethics, duration, time and technical difficulties regarding human

studies [ 1 , 2 ].

Numerous exercise research protocols have been established and used appropriate

animal subjects to study the impacts on cardiovascular health and diseases [ 3 – 8 ].

Proper exercise models using animals are necessary to study cardiophysiological

responses and to develop strategy to recover from cardiovascular abnormalities [ 4 , 9 ,

10 ]. The study of exercise physiology is concerned with how the body adapts physi-

ologically to acute stress of exercise and the chronic stress of physical training [ 3 ].

Any specialized exercise models developed for testing acute and chronic exercise

effects on specific physiological issues should well understand how the animal

model-recorded factors are reflected in the human physiological outcomes [ 3 , 8 ]. For

example, humanized animal exercise models providing insight into the understand-

ing of exercise and exercise physiology were summarized in another study [ 11 ].

It is clear that animal models are an essential tool in cardiovascular researches

where numerous cardiovascular functions and therapeutic targets can be studied.

The goal of animal cardiac exercise research is to improve on how we view human

health and disease in cardiovascular system and build on this improved understand-

ing to further advance clinical outcomes [ 6 ]. In general, animals used in cardiovas-

cular exercise studies are enormously varied from species to species, ranging from

small rodent animals (e.g. mice, rats) to large animals (e.g. rabbits, canine, goats,

sheep, pigs, horses) [ 5 , 12 – 16 ]. It was previously reported that exercise-induced

autonomic regulation was changed in a species-dependent manner [ 16 ]. Even within

a species, several indexes (e.g., animal’s size, gender, age) could be considered in

order to select suitable animals to achieve the research goals [ 3 ]. In animal models,

exercise can be either voluntary (e.g. housing animals with a running wheel) or

forced (e.g. placing animals on a treadmill for a certain period of time). The deter-

minants for achieving expected beneficial effects of exercise are largely dependent

on the designed protocols with chosen animals (species), different types (aerobic,

anaerobic), intensities (vigorous-, modulate-, low-intensity), time (morning, eve-

ning), and duration (acute, chronic) [ 16 – 19 ]. Animal-based cardiovascular exercise

modalities mostly include treadmill running, swimming, voluntary wheel running,

usually coupled with a series of other parameters such as varied intensities, times,

metabolism, and durations [ 17 , 20 – 23 ]. Each chosen experimental protocol should

also describe whether respective exercise treatment has produced the expected acute

V.T. Thu et al.