Arterial stiffness – the preventive effect of vibrotherapy

Arterial stiffness is a very serious health problem that can lead to dangerous consequences. Hypertension, coronary heart disease, myocardial hypertrophy, heart failure, diabetes, hypercholesterolaemia or atherosclerosis are widely known consequences, with stroke and myocardial infarction being the most feared.

Among the treatment methods, the importance of prevention is emphasised, reducing the risk of pathology and its extent. Recent studies point to vibration stimulation as an effective prevention of arterial stiffness.

Vibration versus arterial stiffness

Physical activity, including aerobics or resistance exercise, reduces pulse wave velocity (PWV) and systolic pressure amplification index (AI- augmentation factor), but there are scientific studies confirming that the application of whole-body vibration causes reflex muscle contractions through the ‘Tonic Vibration Reflex’ (TVR – Tonic Vibration Reflex) and thus has an effect on reducing PWV and AI.

Scientific results confirm the above-mentioned effects after just one session of vibration therapy, in healthy young men. Vibration topical therapy, where selected areas of the body are vibrated, has a similar effect. Just ten minutes of topical vibration application in young men, showed decreases in PWV and AI.

A group of researchers from the Miguel de Cervantes European University – Herrera et al. (2011) demonstrated in their study an increase in neuromuscular activation and blood flow in the paralysed limbs of people with spinal cord injury, following a vibration therapy session. Thus suggesting that this method applied topically can reduce PWV and AI in post-stroke patients.

Does vibration work? Research at the University of Florida

A study of the effect of vibration therapy on pulse wave velocity (PWV) and systolic pressure amplification index (AI) was also conducted by Koutnik et al. in 2014. The aim of the study was to investigate the immediate effect of vibration therapy on PWV and AI in post-stroke patients and to compare the paralysed and functional side. The study involved 11 post-stroke patients randomly allocated to 2 groups: without vibration and with vibration at 25 Hz and 2 mm amplitude.

After lying supine for 20 minutes with the legs on the vibration platform, blood pressure, pulse wave velocity, systolic blood pressure gain index were measured in the study group and the control group. Measurements were repeated at 5, 15, 30 min after the start of the treatment in both groups.

Results confirmed the effectiveness of vibration

Already after 10 min of vibration therapy, a reduction in PWV and AI was observed on both the functional leg side and the side of the leg with paresis. After 5 min, the decrease in legPWV (lower limb pulse wave velocity) on the paresis side was -94.0 ± 26.0 cm/s (P = 0.005),and on the able-bodied side -81.9 ± 18.1 cm/s (P = 0. 001), baPWV (ankle-arm pulse wave velocity) on the paresis side -76.6 ± 24.0 cm/s (P = 0.01) and baPWV on the functional side -115.7 ± 22.0 cm/s (P = 0.0001). After 15 min, legPWV on the paresis side decreased -59.2 ± 21.6 cm/s (P = 0.021) and legPWV on the able-bodied side -70.3 ± 14.9 cm/s, (P = 0.001). Both indices remained significantly different from baseline, but only the legPWV of the fit side (P = 0.02) was significantly different from the control group. Significant trial-by-trial interactions were observed for aAIx (aortic growth index) and aAIx@75 (AIx normalised to heart rate of 75 beats/min) indicating that the decrease in aAIx (-3.4 ± 0.65 %, P = 0.001) and aAIx@75 (-3.6 ± P=0.009) were significantly different from baseline after vibration therapy compared to the control group after 5 min. This suggests that peripheral arterial responses are not affected by neuromuscular dysfunction during initial recovery in post-stroke patients using vibration therapy. This study provides evidence for the beneficial effects of vibration therapy on arterial stiffness and aortic wave reflection in post-stroke patients. The magnitude of change in systemic and peripheral PWV after vibration is similar on both the impaired and the functional side, but the reduction in PWV persists longer in the functional leg than in the impaired leg.

The results of the study confirmed that the application of passive leg vibration in ischaemic stroke patients reduced systemic arterial stiffness and aortic wave reflection. This confirms the preventive effect of vibrotherapy, offering the chance to prevent stroke or myocardial infarction, especially in high-risk individuals.

Why is arterial stiffness so dangerous?

An independent factor in stroke is increased central (aortic) arterial stiffness. The terms susceptibility, dilatability and stiffness are used to describe the properties of large arteries. Arterial stiffness is the opposite of their susceptibility (elasticity) and extensibility and leads to a reduction in their cushioning role. This results in an increase in pulse wave velocity (PWV). The stiffer the vessels, the higher the velocity. The decrease in vascular compliance translates into an additional increase in cardiac load. Stiff vessels are not able to cushion the energy thrown into the blood circuit as effectively. The increased load results in myocardial hypertrophy and worsening coronary flow insufficiency.

Vascular stiffness can be one of the causes of hypertension, coronary artery disease, myocardial hypertrophy and heart failure. Early detection of a decrease in arterial elasticity is very important to estimate the risk of serious cardiovascular events.

One problem, many causes. Who is most commonly affected?

Increased stiffness of elastic arteries is the result of gradual degradation of elastin fibres. Very often, increased arterial stiffness is accompanied by impaired endothelial function. This is particularly true in diabetic patients, those with familial hypercholesterolaemia and smokers.

Functional abnormalities associated with a decrease in the production of vasodilatory – vasodilator – substances (nitric oxide) may also be responsible for reduced vascular compliance with age. Increased vascular stiffness is also partly genetically determined.

Sources:

1. Cieslik-Guerra U., Methods for measuring arterial stiffness. Hypertension 2011;15, 1,42-48.

2. Pędzich E., Szmigielski C., Gaciong Z., Central blood pressure as an indicator of risk of cardiovascular complications. Arterial Hypertension 2006; 10.5,341-349.

3. Rajzer M., Kawecka-Jaszcz K., Arterial compliance in arterial hypertension. From pathophysiology to clinical relevance. Hypertension 2002;6,1.

4. Koutnik A. P., Wong A., Kalfon R., Madzima T.A., Figueroa A., Insightful vibration reduces arterial stiffness and aortic wave reflection in post-stroke subjects. Eur J Appl Physiol (2014) 114:105-111.