Abstract:Introduction: Yoga is a system of poses which inducts an effective and vigorous blood circulation and completely eliminates all impurities from the system. In this study, the effect of yogasanas on renal circulation was studied. Twist, back bends, forward folds and inner thigh stretches will increase the abdominal pressure and also stimulate the second chakra to increase the blood flow to the kidney. The study was carried out to evaluate the effects of renal specific asanas in increasing the blood flow to the kidney.Materials and methods:The parameters Peak Systolic Velocity (PSV) and Resistive Index (RI) of renal blood vessels were assessed on forty female subjects in the age group between 17 -19 yrs using a colour Doppler before and after three months of yoga training. This study was conducted in the department of physiology in VMKV medical college, Salem between 4.30-5.30 pm everyday for 5 days in a weekConclusion:Yogasanas are said to increase the blood flow to almost all the parts of the body. Increase in blood flow to the kidney especially helps in removing the waste products thereby preventing water and salt accumulation. Our study confirms that regular practice of yoga helps to maintain a healthy kidney and also, as an adjuvant therapy helps to improve the renal functions in patients who already suffer from renal disorders and reduce the dosage of the drugs.
Health is happiness and it is the most essential ingredient in human existence. Yogasana is the means to that health. Everything said and done regarding yoga must be reasoned, scientific and supported by facts and figures. Yogasana is a system of poses. It inducts an effective and vigorous blood circulation and completely eliminates all impurities from the system. In this study, the effect of yogasanas on renal circulation was studied.
Renal blood flow is determined by the pressure gradient across the renal vasculature (the difference between renal artery and renal vein hydrostatic pressure) divided by the total renal vascular resistance. An increase in resistance of any of the vascular segments of the kidney tends to reduce the renal blood flow, whereas a decrease in vascular resistance increases renal blood flow if renal artery and vein pressures remain constant. Increase in renal blood flow is accompanied by an increase in Glomerular filtration rate (GFR) which increases the elimination of waste products from the body. In conditions like congestive cardiac failure and cirrhosis, GFR is decreased due to increase in renal vascular resistance in an attempt to restore the blood volume towards normal. Patients on ACE inhibitors also tend to have decreased GFR. The renal blood flow has to be monitored in all these conditions to ensure that severe decrease in GFR does not occur. This study was done to evaluate whether yogasanas can increase the blood flow to the kidney.
Materials and methods:
Forty female subjects in the age group between 17 -19 yrs were included in this study after obtaining their informed consent. The Institute Ethics Committee approved the study protocol. The parameters checked are Peak Systolic Velocity (PSV) and Resistive Index (RI) and the measurements were performed at the level of renal artery using a 3.5 MHZ low frequency electronic probe (8) with better penetration to greater depths. The patient is asked to suspend the respiration and a Doppler reading is taken from one of the arteries best aligned to the cursor. Using colour Doppler the measurements were taken after 5 minutes.
To evaluate the right renal artery, the patient is rolled into a left decubitus position. The patient is asked to relax the abdominal muscles as much as possible. The probe is placed in a sagittal view in the soft part of the abdomen below the rib cage. To evaluate the left renal artery, the patient is rolled into a left decubitus position. The probe is placed along a lateral or slightly posterior approach. The intrarenal Doppler waveforms must be obtained at angles less than 30 degrees to visualize the early systolic peak.
All flow velocity wave forms were obtained after angle correction. The spectral wave form tracing is then analyzed for PSV (the Doppler wave form recorded at the point with the highest frequency shift) and RI. Multiple sampling was performed (at an interval of 5 minutes) to account for variations and the mean value was expressed. The mean value found in the right and left sides was used as a representative parameter. RI was calculated using Pourcelot’s formula (RI=PSV-EDV%PSV) to characterize the peripheral vascular resistance of the vessel studied.
Yogasanas to improve the renal function were taught by a certified yoga teacher to the female medical subjects. The training was given for a period of 3 months and the parameters PSV and RI were recorded before and after yoga training to assess the renal blood flow.
- Weight 47+/-8 kgs
- Normal Lipid profile
- Fresh yoga learners
- Age matched, young subjects
- Subjects who were regularly doing yoga
- History of Hypertension
- H/O Diabetes mellitus
- H/O Renal diseases
- Hip, neck and back disorders
- On drug therapy
The yoga training session was conducted in the department of physiology in VMKV medical college, Salem between 4.30-5.30 pm everyday for 5 days in a week. No other physical exercise like swimming, walking, dancing etc was allowed during the period of training. The following renal specific asanas were taught in a well ventilated room with adequate light. The asanas include
1. Bhujangasana 2. Salabasana 3. Paschimothanasana 4. Dhanurasana
5. Ardhamatsyendrasana 6. Matsyasana 7. Mayurasana 8. Trikonasana 9.savasana
All these asanas except savasana were done for 15-20 seconds and then repeated 4 times.
Table: Comparing PSV and RI before and after yoga training
Peak Systolic velocity
|Before yoga training||After yoga training||Before yoga training||After yoga training|
|Right Renal artery||58.8 ± 5.5||70.2 ±5.7||0.68 ±0.02||0.60 ± 0.02|
|Left Renal artery||57.6 ±5.2||69.9 ±5.5||0.68 ± 0.01||0.59 ± 0.02|
P value < 0.0001
The results were analyzed in Microsoft office excel and Graphpad Prism, Peak systolic velocity (PSV) before and after yogasanas were compared and analyzed using Student paired T test. There was significant increase in PSV noted after yoga training from mean value of 58.8cm/sec to 70.2cm/sec and 57.6 cm/sec to 69.9cm/sec in the right renal artery and left renal artery respectively with the P value of less than 0.0001.
Resistive Index (RI) showed significant decrease after yogasana training 0.68 to 0.6 in right side and 0.68 to 0.59 in the left side. The analysis showed results were significant with the P value of less than 0.0001.
Nearly all diseases of the kidney involve the renal blood vessels secondarily. Renal blood flow, which is 25% of the cardiac output supplies the kidneys with nutrients and removes waste products. The purpose of this excessive blood flow to the kidney is to supply enough plasma for the high rates of glomerular filtration that are necessary for precise regulation of body fluid volume and solute concentration. The mechanisms that regulate renal blood flow are closely linked to the control of GFR.
An increase in resistance of any of the vascular segments of the kidney tends to reduce the renal blood flow. Most of the renal vascular resistance resides in 3 major segments: Interlobular arteries, afferent arterioles and efferent arterioles. Decreased blood flow is usually accompanied by decreased GFR and decreased output of water and solutes (5). This can lead to 1.generalised edema (from salt and water retention) 2.acidosis (failure to remove normal acidic products) 3.accumulation of urea, creatinine, uric acid, phenols, potassium, phosphate etc.
Normally a decrease in blood flow to the kidney is sensed by JG cells of afferent arterioles of the kidney which releases renin that acts on angiotensinogen to finally produce Angiotensin II. Angiotensin II corrects water and salt load of the body by causing 1.vasoconstriction of afferent arterioles 2.increasing ADH secretion 3.increasing aldosterone secretion and 4.stimulating thirst centre. Acute, mild changes in renal blood flow and GFR are immediately corrected and maintained by 1.renal auto regulation 2.glomerulo tubular balance 3.pressure dieresis and natriuresis. But in diseased conditions of kidney even the small fluid retention that does occur along with increased secretion of renin and angiotensin II can lead to hypertension.
Yoga helps us give massage to all organs in the body. By stretching stiff muscles, joints will become flexible and blood circulation in body will be improved. The Asanas like bhujangasana, dhanurasana, salabasana, and paschimotanasana (14) all create intra abdominal pressure in varying degrees. There is the force of gravity always acting upon the abdominal organs tending to draw them down but is prevented by the mesenteries. But there is a limit to the strain which these could bear. In pathological conditions of the abdominal organs, they fail to exert pressure. This results in constipation, gastric troubles, sluggishness of kidneys, liver etc. All these kidney specific asanas by increasing the abdominal pressure increases the blood flow to kidney. For example paschimotanasana is a pose which stretches all the posterior parts of the body. The muscles rectus and quadratus lumborum remain contracted, retract the abdominal walls and compress the contents of the abdomen especially during micturition. In mayurasana, the whole weight of the body presses the abdomen at the elbow. The partial inhalation lowers the abdomen against the viscera and the intra abdominal pressure is increased. Bhujangasana (cobra posture) increases linear flow velocity in the renal veins during right atrial systole (9). The kidneys are connected with the second chakra. The meridian line or energy line that stimulates the kidneys runs from the bottom of the 5 th toe and through the inner knee, thigh and sacral region. Twists (ardha matsyendrasana), back bends (dhanurasana), forward folds (paschimotanasana) and inner thigh stretches will stimulate the second chakra and increase the blood flow to the kidney.
Increase in blood flow is assessed by increase in PSV and decrease in RI. Several studies have shown that the normal upper threshold of RI is 0.70(10).The normal Doppler wave form obtained from the renal artery demonstrates a low resistive profile with continuous forward flow throughout the cardiac cycle. A higher RI is measured in vessels with low compliance than in those with excellent compliance (6).Healthy subjects with compliant vessels has greater early systolic peaks.
The vascular resistance and especially the vascular compliance are main predictors of the renal RI. Compliance is the rate of change of volume of a vessel as a function of pressure (2).In the presence of vascular compliance, RI was dependant on vascular resistance and increased with increasing resistance (12). Renal RI is influenced by many cardiovascular factors (11). A high RI of more than 0.80indicates advanced renal damage (1). Renal artery stenosis may induce renovascular hypertension and ischemic nephropathy. Diseases limited to glomeruli do not affect RI (4).Doppler RI was advanced as a useful parameter for quantifying the alterations in renal blood flow that may occur with renal diseases. Doppler waveform analysis of the intra renal arteries improved the accuracy of screening for a significant proximal renal artery stenosis where PSV is more than 150cm/sec. (3, 13). Increase in PSV and the decrease in RI in our study confirms that these asanas increase the blood flow to the kidney.
Yogasanas are said to increase the blood flow to almost all the parts of the body. Increase in blood flow to the kidney especially helps in removing the waste products thereby preventing water and salt accumulation. Our study confirms that regular practice of yoga helps to maintain a healthy kidney and also, as an adjuvant therapy helps to improve the renal functions in patients who already suffer from renal disorders and reduce the dosage of the drugs.