Exercise as it relates to Disease/The effect of resistance training on blood pressure

Resistance Training

Resistance Training (RT) is exercise that emphasises muscle contraction against force. There are three different types of RT: Dynamic, Isometric, and Isokinetic.

Dynamic	Isometric	Isokinetic
The shortening and lengthening of muscle fibres i.e. Eccentric and Concentric contraction.	Applying force to muscle without any change in muscle length.	The application of force across a range of motion at a constant speed.

Blood Pressure

Blood Pressure (BP) is the pressure that blood exerts on the arterial walls as it is pumped from the heart. Measured in millimeters of mercury (mmHg). It is denoted as Systolic BP (SBP) over Diastolic BP (DBP) i.e 120/80.

Type	SBP (mmHg)	DBP (mmHg)
Normotensive	<140	<90
Grade 1 Hypertension	140-159	90-99
Grade 2 Hypertension	160-179	100-109
Grade 3 Hypertension	>180	>110

Normotension

People with BP in normal ranges are termed normotensive.

Hypertension

People with BP above normal ranges are considered hypertensive with three different classifications.

Prevalence

It is estimated that 23.6% of men and 19.5% of women in Australia above the age of 18 are hypertensive.

Causes

• Smoking
• Obesity
• insufficient exercise
• Poor diet

• high salt
• low fluids

Hypotensive

Abnormally low BP. Not strictly defined.

Research

Research on the effects of RT on BP is limited with conclusions varied. The benefits of aerobic exercise for reducing BP are well documented. Studies looking at RT have generally focused on Dynamic Resistance training with very few on Isometric and Isokinetic.

Effect on resting BP in Normotensive Subjects

	Dynamic RT	Isometric RT	Isokinetic RT
Effects	Small reductions in both SBP and DBP	Largest decreases in SBP due to RT (limited research). ↓11 mmHg. ↓6 mmHg in DBP [4]	Not enough evidence

Effect on resting BP in Hypertensive Subjects

	Dynamic RT	Isometric RT	Isokinetic RT
Effects	Small reductions in DBP. ↓3.5 mmHg [4]	Largest decreases in SBP due to RT (limited research). ↓11 mmHg. ↓6 mmHg in DBP [4]	Not enough evidence.

Recommendations

Including RT in an exercise program is beneficial for all with regards to the increased muscle mass and especially the increase in ease of everyday living for the elderly. With regards to including it a hypertensive subjects program come precautions must be taken.

Normotensive

Here there should be no problems including a RT program.

Hypertensive

With regards to using a RT program with high blood pressure subjects, studies have found decreases in BP^[4][7]. The more important factor to consider is that none of these studies have found RT increases resting blood pressure. However slight the decrease in BP achieved through RT, Collins, R. et al. in Kelley & Kelley^[5] found that while it may not affect cardiovascular disease it decreases the chance for stroke or coronary heart disease. During RT BP is elevated by employing some of these techniques we can lower the risk for hypertensive patients during RT. Lamotte, M. Niset, G & Borne, P. found that low weight with high repetitions elevated blood pressure the most, while higher weight with lower repetitions increased BP less significantly. BP's of 320/250 can be seen from heavy 1 repetition maximums (1RM). This increases the chance of bursting capillaries so 1RM's should not be included within an RT for hypertension. Therefore when resistance training hypertensive subjects should use around 75% ^[8] estimated 1RM with no more than 10 repetitions.

Fun Fact

Resistance Training may maintain lowered blood pressure achieved from Aerobic Exercise in the elderly

Further reading

http://weighttraining.about.com/b/2009/07/06/weight-training-lowers-blood-pressure-over-time-but-caution-in-the-gym-still-warranted-for-hypertensives.htm

http://www.mayoclinic.com/health/weightlifting/AN00637

http://jaha.ahajournals.org/content/2/1/e004473.full

http://www.heartfoundation.org.au/SiteCollectionDocuments/Factsheet-High-blood-pressure.pdf