http://www.brianmac.demon.co.uk/articles/scni21a1.htm
Danny M. O'Dell, MA. CSCS*D wrote:While under the heavy bar it is easy to get into the habit of holding your breath during the execution of the lift. Holding your breath does help in moving the heavy iron as it stabilizes your core but it comes with a cost to your overall health. And that cost is a tremendous increase in your blood pressure. High blood pressure has been known to directly cause damage to your body by raising the risk of having a stroke, causing a heart attack, damaging your kidneys and increasing the risk of a blood vessel aneurism. Any of which will cause a quick cessation of your lifting for the day.
http://www.strengthfit.com/modules.php? ... icle&sid=6
Michael Phelps, M.D. wrote:High blood pressure increases the risk of heart failure, renal failure, kidney disease, stroke, and myocardial infarction.
In evaluating the effects of chronic weight training on cardiovascular function it is necessary to be specific as to the type of lifting in question. Weight training consists of three major divisions: bodybuilding, Olympic-style lifting, and power lifting. All three differ in goals, training methods, neuromuscular response, and cardiovascular response. Basically, how one lifts determines the acute and chronic effects of weight training on cardiovascular function.
Olympic-style lifting places the least strain on the cardiovascular system, compared with other types of lifting. Due to the technical nature of the snatch and clean and jerk, full-body movements that are executed quickly with no prolonged breath holding, there is no sharp rise in blood pressure, in contrast to power lifting. Elite Olympic-style lifters (excluding heavyweights) are noted for having a high level of cardiovascular fitness (VO2 max in the low to mid 60’s). The regular performance of high repetition (8 to12) power snatch and power clean using light loads for general bodybuilding purposes has a positive effect on both functional strength and cardiovascular fitness.
Bodybuilding, especially in the form of interval weight training and circuit training, has proven effective in developing combined strength and cardiovascular fitness. Cardiovascular improvement is related to selection of exercises, training intensity, duration of the rest periods between exercises, total number and frequency of training sessions, and initial fitness level. Clinical research indicates that circuit training can produce a significant increase in lean body mass, strength, cardiovascular endurance, and a lower diastolic blood pressure in both healthy and borderline hypertensive individuals. The cardiovascular response to circuit training suggest that this is a safe and acceptable form of exercise for cardiac patients. Using moderate resistance, circuit weight training may be a useful anti-hypertensive therapy.
Power lifting. Of the three forms of weightlifting, power lifting has the greatest potential to produce exercise-induced hypertension. To gain insight as to how internal stress develops within the heart when performing a heavy power lift (bench press, squat or dead lift), we need to look at the acute functional cardiovascular dynamics that occur during lifting.
When a heavy squat, bench press or dead lift is executed the heart is forced to work against a high after-load pressure. After-load pressure develops in response to high arterial blood pressure resulting from a sharp increase in muscle perfusion pressure due to obstruction of blood flow when muscles contract with force. Obstruction is virtually complete when the force of muscle contraction effort reaches 80 percent of maximum. How hard the heart must work during a lift is determined to a great extent by the arterial pressure required to drive the blood through to the muscle tissue that is contracting the hardest. For example, in both power lifting and functional isometric lifting, the muscle tissue pressure upon the arteries is very high, thus requiring a very high perfusion pressure, which, in turn, effects a large increase in blood pressure. The long-term effects of heavy lifting increases left ventricular thickness and mass with no increase in cardiac output. This is a physiological condition, not a pathological one.
Other factors influencing an increase in blood pressure during heavy lifting are prolonged breath holding, including the Valsalva maneuver ( making a forcible expiration against a closed glottis), and wearing a lifting belt, super suit, and knee wraps. Combined, these factors bring about a sharp increase in intra-thoracic pressure from 80 to 200 mm Hg or more. This increased pressure is transmitted through the thin walls of the great veins: venous blood return to the heart is thus severely decreased. The result is a surge in systolic and diastolic pressure (reading up to 400/300 mm Hg have been recorded). Sharp increases in blood pressure of this magnitude is not seen in Olympic-style lifting, as there is no sustained breath holding.
While the acute effects of heavy power lifting on cardiac function poses no health threat to an aerobically fit lifter with normal systolic blood pressure (below 140 mm Hg), they may have serious implications for those with normal diastolic pressure and borderline systolic hypertension (140 to 154 mm Hg). In weightlifting induced hypertension, when the resistance against which the left ventricle must pump (after load) is chronically elevated the cardiac muscle hypertrophies. The total oxygen consumption of the heart, already increased by the work of expelling blood against a raised pressure increases further because there is more cardiac muscle. Therefore, any decrease in venous blood flow to the heart has more serious consequences in borderline hypertensive lifters than is does in normal individuals.
According to The National Heart, Lung and Blood Institute, individuals with borderline hypertension are at greater risk for strokes, heart disease, and kidney failure than comparable people with a normal systolic pressure. Power lifters in the heavier body -weight classes (90 kilos and higher) with systolic hypertension must be considered to be at the greatest risk. The combination of anabolic steroid and growth hormone usage, excessive muscular bulk, and lack of minimal cardiovascular fitness (VO2 max below 35 ml per kilogram of body weight) places such a lifter in the high risk category for heart disease. A study reported in the journal of Hypertension (June 1999), involving 19 male athletes, linked a 12 month weightlifting program designed predominantly to optimize muscular strength, with stiffing of the proximal aorta and leg arteries, which contributed to a higher cardiac after load. The net effect was an increase in resting systolic blood pressure. During the study the subjects refrained from participating in aerobic exercise. The results of the study point out the need for athletes to cross-train for strength and aerobic fitness.
The trouble with heart disease is that the first symptom is often hard to deal with: sudden death.
http://nsca.allenpress.com/nscaonline/? ... 2.0.CO%3B2
Childs, John D. wrote:ONE ON ONE: The Impact of the Valsalva Maneuver During Resistance Exercise
Issn: 1533-4295 Journal: Strength and Conditioning Journal Volume: 21 Issue: 2 Pages: 54-55
Authors: Childs, John D.
Article ID: 10.1519/1533-4295(1999)021<0054:TIOTVM>2.0.CO;2
Clients are especially at risk for abnormally high blood pressure during a Valsalva maneuver. Exercise-induced arterial hypertension from the Valsalva
http://www.fitness-health.co.uk/blood-pressure.htm
The Valsalva Maneuver or holding the breath while performing an exercise can increase blood pressure to extremely high and dangerous levels. Blood pressures of nearly 400/350 have been recorded during such actions. Existing aneurysms can burst, blood vessels in the eye can rupture and even retinas can tear (Valsalva Retinopathy). This is a common and dangerous practice. It is also the job of the trainer or spotter to recognize when the breath is being held and bring it to the exerciser's attention immediately.
A simple google search will produce an enormous volume of research...