Hypertension is a problem. It raises the risk of heart disease; it’s one of the most consisten...
For today’s edition of Dear Mark, I’m answering two questions from readers. First one comes from Debbie, a prolific hiker and backpacker who can’t seem to shake terrible thigh muscle cramps during steep climbs. She’s tried all the conventional advice. She’s taking electrolyte tabs. She’s staying hydrated. Nothing works. What does? And then, Brad wonders about parasympathetic overtraining, a type of overtraining you don’t hear much about. What does it mean and how should he respond?
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For today’s edition of Dear Mark, I’m answering three reader questions. First, if things are going well on a relatively low-calorie intake, should you just keep on keepin’ on or should you increase food intake to “get ahead” of your needs? Next, what’s the deal with a study showing a high-carb diet is better for testosterone levels than a high-protein one? What does this mean for your Primal way of eating? And finally, can an improvement in heart rate variability after a carb refeed indicate a greater need for carbs?
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Regular Mark’s Daily Apple readers know of my enthusiasm for the cutting edge biofeedback technology known as heart rate variability (HRV). There is a detailed introductory post here, and a follow up post here. In short, HRV measures the variation in beat-to-beat intervals of your heart, providing a direct window into the functional state of your autonomic nervous system. A high HRV score (indicative of more variation in beat to beat intervals) suggests a synchronistic balance between your parasympathetic (“rest and digest”) nervous system and your sympathetic (“fight or flight”) nervous system. A lower than normal (for the individual) HRV score is indicative of sympathetic dominance—a state of overstress or poor cardiovascular function.Read More
Last week, I introduced the concept of heart rate variability – the variation of heart beat to beat intervals. Far from the metronome we might assume it to be, the healthiest heart beat follows a fractal pattern, with varying lengths of time separating each pulse. A higher heart rate variability (HRV) suggests a relaxed, low-stress physiological milieu, while a lower HRV indicates a need for recovery, rest, and sleep. That’s why athletes use HRV monitoring to plan their workouts and rest periods, PR attempts and deload weeks: it eliminates the guesswork. Even if you’re not an athlete, the HRV is a strong diagnostic biomarker for general health and resiliency. Today, we’ll be exploring 16 ways to increase it.Read More
People are always looking for that one biomarker to rule them all, the number on a paper that absolutely determines your health, longevity, fitness level, sex appeal, happiness, and productivity. Throughout the years, it’s bounced around as researchers think they’ve found “IT” – from cholesterol to LDL to BMI to small dense LDL to CRP to blood pressure to pulse rate and back again – but we always come up wanting. The “one biomarker” never pans out because biology is complex and irreducible to a single number.
However, there is one biomarker showing promise as a broad indicator of overall health and fitness: heart rate variability (HRV), or the variation in the intervals between heart beats. If your heart beats like a metronome, with intervals of identical length between each pulse, you have low heart rate variability; this is “bad.” If your heart beats follow a more fractal pattern, with beat intervals of varying length, you have high heart rate variability; this is “good.”Read More