Definition of Blood Pressure.
Blood Pressure (BP) is the pressure exerted on blood vessel walls by circulating blood.
What is the difference between Systolic and Diastolic blood pressure?
Systolic blood pressure is the pressure within the arteries when the heart contracts increasing blood flow through the arteries and therefore in turn the pressure. Diastolic pressure is when the heart is at a relaxed state so there is a decreased pressure through the arteries.
The two main determinants of blood pressure are Cardiac Output and Peripheral Resistance.
Cardiac output can be defined as the amount of blood pushed out of the heart in one minute, so the higher the amount the higher the blood pressure. It can be affected by two main determinants which are the stroke volume and heart rate. Generally as the heart rate increases, so does blood pressure, as the increased heart rate will mean more blood will be pushed through the arteries therefore increasing pressure. Stoke volume is normally increased by the body when its put under stress. As this increases it means the amount of blood being pumped out of the heart each beat is increased, and therefore squeezing more through the arteries and increasing blood pressure.
Peripheral resistance is the resistance the blood vessels put on the blood flow throughout the body it can increase and decrease due to vasoconstriction and vasodilatation, depending the stresses that the body is under.
High Blood Pressure (Hypertensive)
Recognised levels of hypertension (high blood pressure) are a systolic level above 160 mm HG or a diastolic of 100 mm HG or more. There are major risks associated with prolonged high blood pressure and these are coronary heart disease, stroke and heart failure. Recognised levels of hypotension (low blood pressure) are systolic readings of 100 mm HG or below or a diastolic reading of 60 or below, there are no real harmful effects of low blood pressure, apart from symptoms of dizziness, loss of consciousness and blurring vision.
Factors that affect a persons Blood Pressure
There are two different types of factors effecting both systolic and diastolic blood pressure these are acute and chronic factors. The acute factors that affect blood pressure (BP) are environmental stressors are placed on the body such as aerobic exercise and heavy weight training which will cause the body to increase the blood flow to cope with the demand of oxygen. Stress and Anxiety increase BP due to the chemicals released that will cause the heart to beat faster and work harder. Things like food, caffeine, and smoking all increase blood flow firstly due to digestion, caffeine increases alertness of the body which causes an increase in cardiac output and smoking inhibits the amount of oxygen we take in which means the heart has to work harder to push the oxygen that does get in the lungs around the body. Also in the long term it causes an increase of cholesterol causes a narrowing of the vessels and therefore increases in blood pressure.
Chronic factors, or more long term factors, that increase blood pressure increase both systolic and diastolic blood pressure. Once again stress and smoking are two factors and causes are as explained above. Nutrition can have a major effect on how the heart operates poor diet can lead to increased cholesterol and the clogging of the arteries etc, which means that pressure through the arteries will be increased due to the smaller circumference of the vessels that need to get through, this can also be applied to the obese person. Finally sedentary lifestyle will mean that the heart will be weak and the vessels will become more inflexible and a hardening of the arteries walls therefore they will not be able to vasodilate as much and therefore increase BP.
Common categories of hypertensive drugs.
What are there main effects and there possible implications for exercise?
The common categories of anti-hypertensive’s are Beta Blockers, calcium channel Blockers, Antiotensin Converting Enzyme Inhibitors and Diuretics.
Beta Blockers – These drugs decrease the heart rate and in turn the cardiac output and increase coronary perfusion. It also decreases stroke volume which in turn again reduces cardiac output. They affect the training by making everything a lot harder and therefore it will seem like there is a decreased effort however there isn’t it’s a decreased workload but still the same amount of effort put in, overall they will slow the person down when training.
Calcium Channel Blockers – These drugs decrease myocardial contractility and block calcium dependent contractions to the smooth muscles in the arteries and in turn this increases vasodilatation. This can cause resting tachycardia (increased heart rate) which needs to be carefully monitored when exercising, also blood pooling can occur if exercised is suddenly stopped therefore it is important to have a long warm down at the end of a session.
Angiotensin Converting Enzyme Inhibitors – These block the angiotenmsin converting enzyme, which stops angiotensin I being converted to angiotensin II which is a powerful vasoconstrictor and this therefore blocks vasoconstriction. In exercise this can lead to dehydration so you must watch fluid intake throughout exercise regime, also as stated above sudden stopping of exercising again can cause blood pooling therefore a long cool down is recommended.
Diuretics – These reduce venous return as they increase secretion from the kidneys of water and sodium ions. Doing this can result in electrolyte imbalances causing a greater loss in potassium and magnesium. This may induce muscles weakness and possible cramps and cardiac dysrhythmias, therefore regular blood test at the doctors should be had to monitor potassium levels in the blood.
Exercise Consideration for people with High Blood Pressure.
Warm up and cool down for about 5-10 minutes to aid in vasodilatation of the vessels in the warm-up preparing the body for exercise and the warm up is essential to help to prevent the onset of post workout hypotension.
Aerobic exercise should initially start at a moderate level of about 60% gradually increasing over a period of 4-6 weeks to 70-75% effort. Effort should be judged using an RPE scale (Rate of Perceived Exertion). Exercise routine should last up to an hour and it is recommended also to do a few 10 minutes spurts of continuous exercise outside of the gymnasium routine.
Resistance work should be low in weight and high in reps about 15-20 per set and exercises should not go until concentric failure, avoid heavy weight above the head, and do not train in positions where the feet are above the head. Make sure there is a spotter there to help and choose more isolation exercises rather than compound movements.
The safest and most effective way to train is with a personal trainer, qualified in dealing with high blood pressure clientele. This will make sure that hypertension suffers will train at there optimum level whilst being exposed to a wide range of training styles, making progression much quicker, more effective and safe.
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