Blood pressure 10/55 mmg. Heart rate 47 bpm. “Are you okay?” the nursed asked me. I smiled and explained how active I am, which is why my levels were so low.
We are used to hearing about high blood pressure, high resting heart rate and high cholesterol, among many other cardiovascular risk markers, but what about when these numbers are low? Are you at risk for heart and cardiovascular problems? Here is a look at what common medical low numbers really mean, if there is a potential problem and what you can do about it.
Low HDL Cholesterol: Not So Good
Total cholesterol is compromised by both LDL and HDL lipoproteins, whose functions oppose each other. When your doctor checks your total cholesterol, he or she will pay attention to these two values right away.
“LDL is like taxi cabs and escorts cholesterol into the arteries. HDL is like taxi cabs and drives cholesterol out of arteries. You need a sizeable number of taxi cabs taking cholesterol out of the arteries to reduce bad cholesterol levels and protect the heart,” says Jim Jirjis, M.D., Assistant Chief Medical Officer of Primary Care and Informatics at Vanderbilt University Medical Center.
You want to keep LDL low —less than 100 mg/dL— while HDL higher than 40 mg/dL for men and 50 mg/dL for women. “Generally, low HDL level is genetic, and is more common in men than in women,” says Keri Peterson, M.D. Likewise, Jirjis points out that some medications, such as progestins and anabolic steroids, may lower the levels. Low HDL means there is less “taxi cabs” to transport out harmful LDL. The more LDL that hangs around increases the risk it can stick to the arteries and form damaging plaque.
What to do? The general advice to reduce total dietary fat intake doesn’t work for HDL. Studies show that when reducing total fat intake, without discriminating among the different types of body fat, you reduce both the good and bad fats: LDL and HDL. So, while cutting back saturated fat is important to reduce overall cardiovascular risk, some foods have shown to increase HDL, such as dark chocolate (rich in flavonoids) and mono-saturated fats like olive and canola oil and avocado.
But to lower LDL and to raise HDL faster, add exercise to your food intake equation. In a systematic review of the current evidence on exercise and cholesterol relationship, the best results were the following:
- Moderate to high intensity aerobic exercise improves HDL levels.
- Resistance exercise works better to decrease the bad cholesterol: LDL.
- Combined exercise —aerobic and resistance— increases HDL and reduces LDL.
Low Blood Pressure: Watch Out
If you are a healthy person who exercises, you probably already enjoy many benefits of a good sweat. When you exercise “there is an increase in cardiac output —i.e., increase the volume of blood pumped from the heart— and a decrease in peripheral vascular resistance,” writes Paul Sorace, James R. Churilla and Peter M. Magyari in the article “Resistance Training for Hypertension,” published in Health & Fitness Journal.
And studies show that both endurance training and circuit type resistance training reduces blood pressure at rest.
Peterson adds that low blood pressure is also common in thin, young women. “As long as you don’t have dizziness or lightheadedness, it’s fine.” However, there are other situations that will need immediate assistance. For example, if your blood pressure’s top number (systolic) is in the 80s this is a sign of potential problems—beware that a normal reading is 120/70 mm HG—such as risk of severe dizziness or even a heart attack, says Peterson. Other causes, although rare, include dehydration —due to not drinking enough or taking diuretics— and adrenal insufficiency, adds Jirjis.
What to do? Keep working out and following an overall a healthy lifestyle. However, if you have symptoms see your doctor.
Low Resting Heart Rate: Fit if You Workout
Exercise reduces resting and submaximal exercise heart rate (workouts below your max heart rate). Training boosts the parasympathetic tone to the pacemaker of the heart at rest, while also increases volume of blood pumped from heart. This means that the heart has longer time to fill out between contractions, which make it pump more blood to the muscles with less effort.
Nevertheless, a low resting heart rate can mean other no-so-healthy issues. “If you aren’t exercising, it could be an arrhythmia,” says Peterson. “Also, certain medications called beta-blockers can slow down your heart rate —they are usually taken when having high blood pressure. While it’s normal to have a resting heart rate in the 70s, some people are also born with rates in the 50s for 60s. If it’s their normal rate then it isn’t a problem.”
What to do? Consult with your doctor about your medications and if you are not fit to help rule out bradycardia (low heart rate), which appears if you have sick sinus syndrome.
Low Sodium: Rare!
The typical Western diet is usually high in sodium, so it is rare for people to have low sodium levels. On the opposite end, some chronic diseases are exacerbated because of extra sodium intake.
“High sodium can trigger increased sodium retention, which can result in increased fluid volume and high blood pressure,” say Thomas P. Martin, Ph.D., FACSM, RCEP and Anastasia N. Fischer, M.D, in their article “Sodium, Potassium and High Blood Pressure” published in the Health & Fitness Journal.
When most people hear their sodium is low, they think they don’t get enough salt, but the real problem is they may be drinking too much water. Sodium levels are measured by how much salt is dissolved per cubic centimeter in the blood, but when there is too much free water in your body sodium gets diluted.
What to do? Be mindful about how much water you drink during exercise. Some people who engage in endurance events often may drink too much water, which puts them at risk of lowering the sodium level. However, in most incidences you need to reduce your overall sodium intake, such as processed food and bread, which have been reported as the main culprits the high sodium levels in the American diet.
Low Potassium: Not So Good
The adequate intake of potassium is 4,700 mg/day, yet the average men intake is 3,200 mg/day and 2,400 mg/day for women.
“A moderate potassium deficiency is characterized by increased blood pressure, increased risk of kidney stones, increased urinary excretion of calcium and salt sensitivity,” says Martin and Fischer. “Potassium blunts the effects of sodium and is therefore important in the control of blood pressure.”
In some extreme cases, diarrhea and vomiting or some weight loss pills (diuretics) can cause abnormally low levels of potassium —known as hypokalemia— which requires immediate medical attention.
What to do? Increase your intake of foods rich in potassium, such as raisins (1 cup has 1,086 mg of potassium), potato with the skin (1,081 mg of potassium), beans, spinach, yogurt, oranges, avocados and tomatoes.
Marta Montenegro is an exercise physiologist, certified strength and conditioning coach and master trainer, who teaches as an adjunct professor at Florida International University. Marta has developed her own system of exercises used by professional athletes. Her personal website, martamontenegro.com, combines fitness, nutrition and health tips, exercise routines, recipes and the latest news to help you change your life but not your lifestyle. She was the founder of nationally awarded SOBeFiT magazine and the fitness DVD series Montenegro Method.