Article by Dr Paul Batman Ph.D

There is always a consequence…..what the wrong type of physical activity can do to your blood vessels!

It is widely accepted that cardiovascular disease is amongst the leading causes of death in the developed world, often associated with affluence and economic growth.

Consequences

One risk factor acutely associated with cardiovascular disease is endothelial dysfunction. The endothelium is the inner lining of blood vessels responsible for the dilation and constriction effects of the blood vessel, regulation of the nerve supply, promotion of vascular changes, the control of inflammation, and increases in the production of nitric oxide.

The endothelium covers all the internal surfaces of blood vessels, cardiac valves and other internal cavities. Any imbalance in these functions renders a condition called endothelial dysfunction. This imbalance can be caused by the unavailability of nitric oxide (NO), an increase in free radical production and an increase in endothelial activity.

Risk factors associated with endothelial dysfunction include smoking, obesity, diabetes, hypertension, high cholesterol levels and sedentary behaviour.

Aerobic exercise produces positive changes in nitric oxide (NO) production in the lining of the artery, increase in vascular endothelial growth factor and an increase in the antioxidant defence system.

Endothelial cells

If nitric oxide formation is interrupted then constriction of the blood vessel predominates.

If the formation of nitric oxide remains low in a number of different blood vessels there is a strong possibility of a reduction in blood flow to the inner lining and the formation of a coagulation or eventually a clot or thrombus, damaging the arterial wall and predisposing the body to the onset of cardiovascular disease. On the other hand an excess of nitric oxide can result from dilation of vessels and the promotion of shock due to the redistribution of blood flow.

A consequence of any damage to the endothelial wall has been reported as the starting point for atherosclerosis (narrowing and hardening of the arteries) and/or cardiovascular disease.

In ageing endothelial dysfunction is often regarded as the starting point to cardiovascular damage. Damage to the endothelial changes the vessels dilation responses, anti-clotting mechanisms and produces ongoing adverse structural changes.

Regular moderate physical activity can enhance blood vessel structure and improve its function. This can be caused by an increase in blood flow. These long term response occur to a more significant degree in slow twitch motor units that are more sensitive to moderate intensity physical activity performed for longer time periods either continuously or discontinuously.

One reason given for the damaging changes to the endothelium is the insufficient supply of nitric oxide, which is caused by oxidative stress (uncontrolled free radical production), inflammation of the lining of the blood vessel, erosion of the cells and the constriction of the blood vessel.

Currently, the increased oxidative stress can be caused by the release of free radicals that cannot be neutralised, which reduces the amount of nitric oxide in the artery wall. These free radicals cause the deactivation of the endothelial receptors responsible for the production of nitric oxide. This response stops the endothelial cells from dilating potentially causing a build up of plaque and a narrowing of the blood vessels.

HIIT

While the benefits of physical activity such as positive changes in blood pressure, blood lipid profiles and glucose metabolism are widely known to improve endothelial (artery wall) performance, the exercise intensity to improve these components is still open to debate.

As a general rule moderate intensity physical activity on a frequent basis improves health by improving the antioxidant defence mechanisms in both healthy individuals and those diagnosed with hypertension.

In more vigorous or high intensity exercise, there is a greater production of uncontrolled free radicals that can have a potential negative effect on both skeletal and cardiac muscle tissue. It must be remembered that intensity of movement whether it be fitness centre based or lifestyle based is relative to the fitness of the individual as well as their health status. Unfit people can improve their VO2 max with what a fit individual would regard as moderate intensity yet intense for the unfit.

There seems little doubt that improvements in maximum aerobic capacity are dependent upon vigorous high intense activity. This would indicate that aerobic fitness improvements are intensity based.

Responses such as cardiac muscle hypertrophy and calcium handling are more sensitive to vigorous exercise generally of a discontinuous or interval raining nature.

Conversely moderate intensity appears to produce more significant changes in endothelial function.

In any type of aerobic activity it is important to improve the muscle’s blood flow and arterial conductance in order to improve general physical performance. However, endothelial changes appear to reach their maximum effect at moderate intensity mainly due to increased production of nitric oxide at these levels.

It has been reported that high intensity occupations over a long time period in males aged between 42-60 years of age has been associated with accelerated progression of carotid atherosclerosis (narrowing and hardening of arteries in the neck) indicating an impaired functioning of the blood vessel endothelium at higher levels of intensity.

The position at the moment suggests that high intensity exercise that is beyond the capability of the client can result in a turning off of the production of nitric oxide in the walls of the artery potentially initiating adverse changes leading to atherosclerosis or hardening of the arteries.

Physical activity must be progressive in nature. You should start at the lower to moderate intensity levels building to the more intensity training methods. Some unfit, overweight, older and or younger clients can be placed at risk without a progression to high intensity physical activity.

Remember if you are training clients you have a “duty of care” to ensure a safe exercise environment.    

Why not consider taking part in one of our advanced modules where you can learn how to develop HIIT programmes and programmes for weight management.

PB award PicDr Paul Batman Ph.D Biography

Paul has over 15 years’ experience in the vocational education sector as a business owner, lecturer and course developer. Originally Paul worked for 20 years as a Senior Lecturer in Exercise and Sports Science and Physical Education at Universities throughout Australia, including UNSW and ACPE and is well recognised in the fitness industry having lectured to over 30,000 + prospective fitness trainers in a variety of settings.

Paul is widely known throughout the fitness industry. Apart from co-authoring most of the fitness texts currently used by a host of other course providers, he has also authored over 10 books and 100 magazine and journal articles. He has also presented at major international conferences in Australia, USA, Canada and the United Kingdom over the past 30 years.

Dr Batman’s main current research interest is in: NEAT (Non Exercise Activity Thermogenesis). In recognition of his contribution to the fields of education, exercise science, health and fitness at the tertiary and vocational education level, Paul was awarded a Lifetime Achievement Award in 2012.