You know how when you go to your doctor and s/he prescribes a medication, there’s a lot of precision behind that prescription? Your doctor will tell you:
- The name of the medication
- The dosage
- Whether to take it with food or without food
- Whether to take it in the morning or the evening
And yet, when your doctor recommends exercise, they just leave it at that: “you should exercise. It’s good for you.” But no more details than that. You have to guess important details, like:
- Should you do cardio, strength training or stretching?
- How many days per week?
- At what intensity (heart rate, perceived exertion, or percentage of your maximum weight)?
- For what duration?
Just as a doctor would not prescribe the same medication for different conditions, nor does it make sense to do the same type of exercise for different conditions. What’s good for one can be bad for another. Hence the need for precision in exercise prescription.
This article will give you that precision, whether you’re a lay person, a medical professional, or a fitness professional.
This article will cover:
- The effects of cardio
- The mechanisms behind how cardio lowers blood pressure
- The effects of strength training.
- The mechanisms behind strength training’s anti-hypertensive effects
- The effects of combining cardio with strength training. Do they add to each other’s effects? Or cancel them out?
- When exercise does not work. Nothing works 100% of the time, for 100% of people, so it’s important to identify for whom exercise will not be effective.
- Bottom line: key exercise recommendations and takeaways.
Ready? Let’s get started.
The Effects of Cardio on Blood Pressure
There has been a lot of research done on how cardio affects blood pressure, all meant to answer different questions.
They found that a single workout lowers blood pressure by between 5-7 mmHg. If your regular blood pressure is 140/90, a single workout can lower it down as low as 133/83. Not bad. And the effects last for 24 hours afterwards.
This drop in blood pressure after exercise is called “post exercise hypotension” (or PEH for short).
A study by leading scientists on exercise and ambulatory blood pressure wanted to compare the effects of steady training (where you maintain the same pace for 20+ minutes) against interval training (where you go fast for 30 seconds to 3 minutes, and then, you go slow for that same period of time). In both cases, the results slightly favoured steady state training. In the group that did steady state, both their systolic and diastolic blood pressure fell by 4-8 mmHg. The group that did interval training had a drop of 5-6 mmHg, but only in the diastolic blood pressure.
If all this talk of “systolic” and “diastolic” blood pressure means nothing to you, let me explain (or just check out the diagram below). You know how when you get your blood pressure reading, it says (for example) 120/80? The top number (120) is your systolic blood pressure. And the bottom number (80) is your diastolic blood pressure. Your systolic blood pressure is how much pressure your blood exerts against the arteries when your heart contracts. Your diastolic blood pressure is how much pressure your blood exerts against the arteries when your heart relaxes. Capisce?
Recently, some scientists comparing exercise intensity and hypotension3 wanted to answer the question of optimal intensity. Is there an optimal intensity at which to exercise to lower blood pressure? Is it a “more is better” type of thing, or is there a point which is optimal? The short answer: it seems that yes, in this case, more is better. Here’s what they did:
They took 45 middle-aged, overweight men with blood pressures ranging from 120/80 (the average was 144.5/84.4 mmHg), up to 159/99, and poor cholesterol profiles. They were divided into 4 groups:
Group 1 did nothing. They were the control group
Group 2 exercised at 40% of their maximal aerobic capacity
Group 3 exercised at 60% of their maximal aerobic capacity
Group 4 went all out, and exercised at 100% of their maximal capacity
The results were:
- Group 2 reduced their systolic blood pressure by an average of 2.8 mmHg, and their diastolic blood pressure by 1.5 mmHg.
- Group 3 reduced their systolic blood pressure by an average of 5.4 mmHg, and their diastolic by 2.0 mmHg.
- Group 4 reduced their systolic blood pressure by an average of 11.7 mmHg, and their diastolic by 4.9 mmHg.
And a study by leading sports scientists 4 wanted to answer the question of
whether there was a difference between the effects of a single workout, and long-term training. The short answer: there isn’t. With aerobic exercise (cardio), if you stop exercising, your blood pressure rises back up. The verdict is: just like with medications: if you stop taking them, blood pressure rises, the same happens with cardio. You stop doing your cardio, your blood pressure rises as well.
This, however is in contrast to strength training. With strength training, any drops in blood pressure are actually maintained once you stop working out. Not forever, but for a few weeks, up to a few months. We’ll talk about that in greater detail later.
The final piece of the puzzle is duration. What’s the least amount of time that you need to exercise to lower your blood pressure?
A study published recently on the influence of dynamic exercise on blood pressure decided to investigate that.
The researchers took 45 men with high blood pressure (average of 144.6/85.2), and divided them into 5 groups:
Group 1 was the control group. They didn’t exercise.
Group 2 exercised for 15 minutes at a low intensity (40%)
Group 3 exercised for 15 minutes at a moderate intensity (60%)
Group 4 exercised for 30 minutes at a low intensity (40%)
Group 5 exercised for 30 minutes at a moderate intensity (60%)
Even with only 15 minutes of exercise and a low intensity, group 2 lowered their systolic blood pressure by 5.6 mmHg (which is almost 19% of the excess blood pressure). Diastolic blood pressure was reduced by 2.1 mmHg (which is almost 21% of the excess blood pressure).
There are of course greater reductions with greater durations and greater intensities, but this previous study didn’t look at “what’s optimum?” Rather, they looked at “what’s minimum? What’s the least you can do, and still get a benefit?” And the answer is “just 15 minutes, at a fairly low intensity.”
The answer to “what’s optimum” is much more complicated than “what’s the minimum?” And unfortunately, that answer doesn’t exist yet, since there’s no universal optimum. What’s optimum for men might or might not be different for women (it hasn’t been investigated yet). What’s optimum might differ based on whether you have prehypertension (blood pressures from 120/80, up to 139/89), or full-out hypertension (higher than 140/90). Or it might not. Again, we don’t know. Optimum might differ based on whether someone is taking medications or not taking medications. Or it might not. Once again, we don’t know.
So yes, there is still a lot that is unknown about exercise and blood pressure, but in this section, you saw the available information on how different variables affect it.
How Cardio Works to Lower Blood Pressure (The Mechanisms)
In the previous section, we learned that cardio does indeed work to lower blood pressure. If that’s good enough for you, and you don’t care about the mechanisms, you can skip this section. But if you’re my geeky friend, and you want to know, keep reading.
Currently, there are 3 known potential mechanisms by which cardio lowers blood pressure.
Mechanism #1: Increased Arterial Diameter
In someone who has high blood pressure, one layer of the artery, called the “intima media” gets thicker. Like a muscle gets thicker from strength training, so too does this layer of the artery as a result of high blood pressure.
A group of researchers, found that the thickness of the intima media decreases as a result of cardio. As a result of decreased thickness, the diameter increases.
Mechanism #2: Increased Bioavailability of Nitric Oxide
Nitric oxide is a molecule inside the body that helps “open up” blood vessels. We all have it, but those with high blood pressure simply can’t use it effectively.
A study published7 on systemic alpha-adrenergic and nitric oxide inhibition on basal limb blood flow in middle age and older individuals, found that aerobic exercise re-sensitizes the cells to nitric oxide, so it can exert its artery-widening effects again.
Mechanism #3: Increased Baroreflex Sensitivity
Don’t let your brain shut off when you read the word “baroreflex.” In typical Igor-fashion, I won’t leave you hanging there with terminology you don’t know.
What is the baroreflex? The nervous system has receptors all over the body that send information back up to the nervous system about different kinds of information. For example, mechanoreceptors are found in muscles and joints, and they send information to the nervous system about mechanical stimuli (like touch). Thermoreceptors are found in the skin, and they send information about temperature.
Likewise, baroreceptors are found in arteries, and they send information to the nervous system about pressure.
In someone with high blood pressure, the sensitivity of the baroreceptors decreases. They don’t receive or send clear signals from and to the nervous system.
With cardio, the signals are clearer, and the nervous system is able to regulate blood pressure better.
Study these mechanisms. I’ll quiz you on them when I see you 😉
The Effects of Strength Training
Typically, when medical professionals tell you that you should exercise, they mostly refer to cardio, so cardio has been extremely well studied. Strength training, on the other hand, not as much. Nonetheless, over the last couple of decades, the research on strength training has been mounting, and a lot of questions are being answered.
Although there is more research available on aerobic exercise (cardio), and there’s more agreement between studies, with strength training, there is some conflicting research. Yet, in the studies that show a positive effect on blood pressure from strength training, the drops are larger than with cardio.
In 2013, a research team, studied a group of elderly people with high blood pressure exercised under 2 different conditions:
- Condition 1: they did strength training with 50% of their maximal weight,
- Condition 2: they exercised at 80% of the maximal weight.
The exercises were identical. When they exercised at 50% of their maximum, their blood pressure was reduced by 23/7 mmHg (down from 147/93 mmHg). But at 80%, their blood pressure was reduced by 33/15 (down from 148/90 mmHg).
If you’re reading this, and thinking “I have to test my maximal weight”, don’t. Not unless you’re doing it under professional supervision (if they think it’s a good idea). For your purposes, a general guideline is that at 80% of your maximal weight, you can do around 10 reps (give or take two) before you can’t do any more. At 50% of your maximal weight, you might be about to do 25-30 reps.
Traditionally, it has been recommended that people with high blood pressure avoid very heavy weights, because heavier weights raise blood pressure too high. And that is true. However, after the end of the exercise, blood pressure returns to normal within about 10 seconds. This has been most advice to stay on the safe side, “just in case”, but really, we don’t know how risky heavy weights are for people with high blood pressure. In this study, heavy weights were more beneficial than light weights, but keep in mind, that the participants were exercising under medical supervision. Until further research is available on the risk-to-benefit ratio of heavy weights in people with high blood pressure, I’d advise the same thing: don’t do it. How heavy is heavy? If you can’t do it more than 5 times, it’s heavy.
We know that with cardio, the effects of cardio last for only about a day. You stop doing cardio, and blood pressure rises. With strength training, it seems to be a bit different.
According to a 2014 study it was found that in elderly sedentary women who were strength training on a regular basis for at least 14 weeks, and then stopped strength training, their blood pressure stayed low for up to 14 weeks without exercise. What happened beyond the 14 weeks? We don’t know. The researchers didn’t measure beyond that. But it’s nice to know that even if you miss a few days, your blood pressure won’t shoot back up.
Here’s another cool effect of strength training: according to some studies (like research on resistance training and blood pressure10 and studies undertaken on strength training and haemodynamic response11), even in the cases when strength training doesn’t decrease blood pressure at rest, it does minimize the rise in blood pressure during cardio.
Lately, a little bit of research has been coming out on the very impressive effects of static strength training on blood pressure. What’s the difference between static strength training, and dynamic strength training? Dynamic strength training (AKA isotonic strength training) is the stuff you usually see at the gym, and most of the exercises that you think of, like squats, deadlifts, bench press, overhead press, etc. Static strength training (AKA isometrics) is when you hold a position, or squeeze a muscle.
As it’s done in research, scientists make the participants squeeze a device called a “hand grip dynamometer.”
They do it for 4 sets of 2 minutes, at 30% of their maximum, resting 3 minutes between sets, and they do this 3 times per week. That’s only 8 minutes of “exercise”, 3 times per week.
Although the research on static strength training (specifically, grip training) is in its infancy, the results are promising. One meta-analysis conducted in 2010 , found reductions of 15.3/7.8 mmHg. Better than the effects seen with cardio, and it only takes 8 minutes per day, 3 times per week. Almost sounds like an infomercial, but this is what the current available research is showing.
Again, it’s still in its infancy, and much more research is necessary, but for a very small time investment, the payoff in results can be very impressive.
Although research on strength training is growing, there is still not much information to answer the questions of “what’s the optimal frequency?”, “what’s the minimal frequency?”, “what’s the optimal intensity?”, “what’s the minimal intensity?”, and others.
At best, we can say that we know strength training is good, but we don’t yet know the optimal protocols, or the smallest “dose” necessary to have an effect.
How Does Strength Training Work?
As mentioned earlier, not as much is known about strength training as about cardio in relation to high blood pressure, but from the little we do know, the primary mechanism by which strength training reduces blood pressure is also through reduced thickness of the artery wall, according to clinical trials on artery adaptations published recently.
There are likely other mechanisms at work, but we’re not yet sure what they are. After all, what is it about strength training that makes the effects last when someone takes a 14-week break from it, but with cardio the effects are gone after 1 day? There has to be more at play.
The Effects of Concurrent Training: Do You Get Better Effects When Combining Strength Training with Cardio?
We know that cardio lowers blood pressure, and strength training also lowers blood pressure. So in theory, you would think that combining cardio and strength training would lower blood pressure more. After all, 1+1= 2. Right? Well, that’s actually not so clear, and the research on that is pretty mixed.
The research, however, is clear on one thing: there is no additive effect. At best, doing concurrent training is no better than doing either cardio or strength training by itself. At worst, the effects of cardio and strength training cancel each other out, and there’s no effect on blood pressure whatsoever.
In one study on acute and chronic cardiovascular responses14, the researchers had hypertensive older women, who were taking medications for their blood pressure perform both strength training and cardio in the same workout. The results were disappointing. Average blood pressure dropped by about 3-5 mmHg. Both cardio and strength training by themselves have stronger effects.
Unfortunately, there are no studies showing that blood pressure drops are better with concurrent training than with either cardio or strength training in isolation.
The inquisitive folks might be wondering “why?” Why are there no additive effects when you combine cardio with strength training? Unfortunately, the research doesn’t really try to answer that question, so I’ll give my opinion.
I think that one possible mechanism is the “ceiling effect.” That is, after blood pressure has already dropped a substantial amount, and gotten close to normal, it may be hard (and unnecessary) to drop it even lower.
Interestingly enough, though there is evidence that shows that order matters. Should you do cardio before strength training, or strength training before cardio? According to the previous study, doing cardio after strength training results in larger drops in blood pressure, compared to strength training after cardio. Cool, eh?
When Exercise Does Not Work to Lower Blood Pressure
We wish that exercise worked for everyone all the time, but unfortunately nothing works for 100% of the people, 100% of the time. Not medications, not surgery, and not exercise.
Therefore, it’s important to know when exercise does not work.
First of all, exercise fails to lower blood pressure about 20-25% of the time. That doesn’t mean it doesn’t have other benefits. It’ll make you stronger, give you more endurance, have positive effects on other systems of your body (your nervous system, endocrine system, immune system, etc.). It just won’t affect your blood pressure.
Fortunately, you know very quickly whether you’re a “non-responder.” Given that drops in blood pressure are seen in a matter of hours after exercise, and they’re the same for first-time exercisers as well as experienced exercisers, if after the first session, your blood pressure doesn’t drop in a matter of a few hours, you might be a non-responder to exercise (again, only as far as blood pressure is concerned. It’ll have other positive effects outside of blood pressure).
Some very preliminary research suggests that the non-responders likely have high CRP and fibrinogen levels (these are both markers of inflammation) in addition to their high blood pressure. This may be tied to high stress levels and/or poor sleep. However, those with high blood sugar levels, and a poor cholesterol profile do respond very well to exercise.
Again, I want to emphasize that this doesn’t mean that if your blood pressure doesn’t change in response to exercise that it means that exercise is useless. It just means that it doesn’t affect your blood pressure, but it will positively affect a lot of other things, like your strength, energy levels, mobility, and more.
Safety Precautions Before Exercise (Neglect These at Your Own Risk)
You’ve now read all about the benefits of exercise, and are excited by the blood pressure-lowering potential of it. You can’t wait to jump in.
But I’d advise you to wait. Don’t start exercising yet. If you haven’t exercised in a long time (that’s 6 months or longer), the American Heart Association, in its position statement16, titled “ Placing the Risks Into Perspective: A Scientific Statement From the American Heart Association Council on Nutrition, Physical Activity, and Metabolism and the Council on Clinical Cardiology”, recommends testing before you jump into a vigorous exercise program (anything over 70% of your maximal heart rate).
They recommend doing 2 tests to clear you for exercise:
- The cardiac stress test
- Atherosclerotic risk profile
Speak to your doctor about running these two tests to see if the benefits of vigorous exercise outweigh the risks for you. If you already have high blood pressure, and you choose to skip these two tests may expose you to unnecessary risk of a heart attack or stroke – the very things you’re trying to avoid.
When NOT to Exercise
Exercise is definitely good for you, but like anything, it carries with it some inherent risks. The healthier you are, the lower your risks.
But there are 2 cases when you should NOT exercise, according to a study on exercise and cardiovascular health.
If you wake up one day, and your systolic blood pressure is over 200 mmHg, or your diastolic is above 110 mmHg at rest.
- If during exercise, your blood pressure goes above 250mmHg for your systolic, and 115 mmHg for your diastolic. Stop your exercise immediately, and seek medical attention.
Bottom Line and Key Takeaways
With all this information, what’s the bottom line? What do I recommend?
If you (or your patient) are a regular exerciser, and you’ve built the habit of exercise, then follow the available evidence:
- Do cardio 3-5 days per week:
The intensity should be over 75% of your maximal heart rate (which, theoretically is 220 minus your age. So if you’re 60, your maximum is theoretically 160, and 75% of that is 120 beats per minute).
Do it for about 30-50 minutes each workout
The type doesn’t matter, whether you’re jogging, or cycling, or swimming, or on the elliptical.
- Do strength training 2-3 times per week:
Lift weights heavy enough that you can’t do them more than 20 times, but light enough that you can do more than 5 times.
Do 2-5 sets per exercise
Do 8-10 exercises per workout
If you (or your patient) are not a regular exerciser, go with the “low-dose, high- effectiveness” training:
- Squeeze both hands into fists with about 30% of your full force
- Hold for 2 minutes per contraction.
- Repeat 4 times, resting 3 minutes in between contractions
- Do this 3 times per week
Although this type of training has no proven benefit on your endurance, or other markers of health (like blood sugar, cholesterol, inflammation, etc.), it does work to reduce blood pressure. And doing this is better than doing nothing.