HRV Measurement Frequency: Comparing 3 day to 7 day per week recordings


There is very little longitudinal HRV data within the research, particularly in team sport athletes. In many cases, HRV will be assessed pre and post or pre, mid and post of a pre-season camp or what have you. This is very likely due to the inconvenience of acquiring this type of data in athletic populations. For the study to be research quality, validated tools must be used (ECG, Polar, Suunto, Omegawave, etc.). In addition, standard measurement procedures are required to ensure that the data is of sufficient quality. This generally involves a 5 minute rest period followed by a 5 minute recording. However, some researchers have used shorter resting and recording durations. Measurement standards for athlete monitoring in the field need to be developed. This is an area my colleague Dr. Esco and I are working on in our lab. This includes cross-validating field HRV tools, assessing the suitability of…

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HRV in a bit more detail


Over the next several posts I will attempt to provide a little more depth to the typical explanations of heart rate variability that I’ve provided in the past. I will be displaying ECG data and HRV software screen shots to provide a better visual representation of HRV analysis. I will present and discuss things like;

  • How HRV data is often collected and analyzed
  • ECG basics
  • What respiratory sinus arrhythmia looks like
  • What an ectopic beat looks like
  • What a tachogram is and looks like (HRV software)
  • Comparing athlete to non-athlete ECG/HRV data
  • Looking at supine and standing ECG/HRV data
  • Looking at paced vs. spontaneous breathing data and how it affects HRV
  • Showing how subtle errors can impact an HRV measurement
  • Discussing HRV research questions that my colleague and I are investigating here in our lab
  • Whatever else seems  relevant as I get writing

Today’s post will serve as a brief…

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Reviewing HRV, RPE, 1RM and Grip Strength Data Over 6 Weeks


I’ve been continuing to collect data on a competitive powerlifter that trains out of our facilities here at AUM. This athlete has cerebral palsy and therefore only competes in raw bench press. Currently, he can press approximately 2.21x his bodyweight (265lbs at 120lb).  I’ve posted his older training cycle data previously here and here. This time around, I’ve been tracking a few different variables that are listed and described below. The purpose of this was to see if any of the monitored variables were able to reflect or predict daily variations in 1RM strength.

1RM – Unlike previous cycles, I calculated his 1RM bench press each session based on reps performed and RPE. For example; on his first working set of the day, if he performed 3 reps at an RPE of 9 (1 rep left in the tank), this was considered a 4RM weight and approximately 85% of…

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Advances in Aerobic Training: How to Apply the New Heart Rate Formulas

link Advances in Aerobic Training: How to Apply the New Heart Rate Formulas

Science and technology advancements mean that our knowledge of fitness is constantly evolving. What was once standard practice, such as calculating maximum heart rate, can quickly become outdated and irrelevant. In this article, I will explain how to apply some of the newer formulas for calculating heart rate and intensity, and how these new tools may make it easier to help your clients build a stronger base of fitness.

New Formulas for Calculating Heart Rate

To determine maximum heart rate, the old method was to subtract your age from 220. From there you would simply calculate the remaining number by some percentage to determine your training heart rate or training zone. The new way (which is not at simple, but is more accurate) to calculate maximum heart rate corrects for both younger (below 25 years) and older (over 55 years) people. There are many new maximum heart-rate formulas to choose from, but ACE uses 208 minus (.7 * age). Thus a 50 year old would be 208 minus (.7 *50) or 208 – 35 = 173. The old formula gives a result that is only 3 beats lower, but at 70 years of age this difference is a significant 9 beats per minute.

The other major shift is in the use of the heart-rate reserve (HRR) or Karvonen formula. Subtract your resting heart rate from the number derived from the new maximum heart-rate formula described above—this will give you your heart-rate reserve. Multiple that HRR number by some percentage, say 70%, then add back the resting heart rate to get your training rate. For example, if you are 25, and your maximum heart rate was calculated at 190, and your resting heart rate is 60, then your HRR is 190 – 60 = 130. You then multiply this by .7 to get 91, and add back the resting 91 + 60 = 151, which as a 70% HRR training level for you. If you wanted to go to 80% HRR, your calculations would look like this: 130 *.8 = 104 and 104 + 60 = 164. So, you would train between 164 and 151 to be in the high end of your aerobic zone.

A Shortcut Method: The 180 System

The “180 system” was designed by Dr. Phil Maffetone, the physician who designed an aerobic-conditioning program for Mark Allen, arguably the greatest triathlete in the history of the sport. He believed that you could take 180 minus an individual’s age to figure out his or her maximum aerobic heart rate with some correction factors. The main corrections are needed for age and conditioning effect, or both.

    • If you don’t work out à subtract 5 beats
    • If you only work out 1-2 days/week à subtract 2-3 bpm
    •  If you work out 3-4x/week, no change
    • If you work out 5-6x/week, no change
    • If you work out 7+/week for more than 1 year à add 5
    • If you are over 55 or under 25 à add 5
    • If you are 60 years or older or under 20 à add 5 more

So, for a 40-year-old, the calculation would be 180 – 40 = 140, while for the 25-year-old described earlier, you would add 5 beats for a 145 maximum aerobic training zone. The system allows the body to adapt to this heart rate and the speed will gradually increase until a plateau. Then you switch to anaerobic interval training as the primary modality. Dr. Maffetone warns it will take several months or even up to a year to see large differences in speed. Mark Allen shifted from an 8:15 minute/mile pace to a 5:20 pace at his 180-system heart rate. To this day, Mark has the fastest marathon split in the Hawaii Ironman at 2 hours and 40 minutes for his particular course.

The system is not meant to pound you into the ground, but rather let you feel refreshed and able to train the next day. In fact, the system requires you to do a high volume of training for maximum effectiveness. You should strive for two to three hours of training at this intensity in a week.

It should be noted that this is not the same as high-intensity interval training (HIIT) and may not elicit the super-fast results people expect. However, building the aerobic base slowly and surely across time is what 90 percent of all competitive endurance athletes still do.

HRV and Training Cycle Review of Powerlifter with CP


I’ve been continuing to work with Zarius out of our lab here at AUM. I provided a detailed account of his  recent powerlifting meet prep and competition data in this post. Zarius is 22 years old, weighs 120lbs and has Cerebral Palsy. Due to travel/work schedules we have had a hard time completing a solid training cycle since his last competition earlier this summer. We were finally able to get a good 1 month of training in before one of us had to travel again. Here is an overview of the training and HRV data from our most recent training cycle.

The Plan:

Our schedules allow for 3 training days per week. We train full body every Mon-Wed-Fri. Zarius is able to do some lower body exercises and we always finish each session with some walking laps around the track. (As an aside, prior to getting involved with the Human…

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Training Adaptation and Heart Rate Variability in Elite Endurance Athletes: Opening the Door to Effective Monitoring

Training Adaptation and Heart Rate Variability in Elite Endurance Athletes: Opening the Door to Effective Monitoring

Who, what, why?

A distinguished team, headed by Dr Martin Buchheit and complemented by national institute sports performance specialists from New Zealand and Australia, have created a review paper that takes a critical look at the way in which heart rate variability (HRV) has been used in elite sports. Dr Buchheit has over 90 publications in the area of HRV, sports performance, health & recovery, and currently works for the renowned ASPIRE sports facility in Qatar.

The review highlights the potential issues and pitfalls of using HRV for performance & training monitoring and makes practical recommendations for how to apply HRV monitoring for best results.

What did they do?

The team reviewed a number of studies (67, including some of their own), where HRV had been investigated in response to athlete adaptation and changes in training load, looking especially at the HRV collection & analysis methods.  The researchers looked at vagal (parasympathetic) measures of HRV taken upon waking in the morning as these provide the best practical utility for individuals and coaches wanting to adjust training or make player selections for that day.

They used this review to derive recommendations on how HRV should best be monitored and assessed, with example data from elite endurance athletes.

What did they find?

I’m presenting this part as a list in order to make it more useful & easier to digest.  If you are interested in the fine detail & justification I’d recommend reading the full paper – it’s a good piece and you can find a link below.

  1. In moderately trained (i.e. non elite) athletes, moderate training loads increase HRV in parallel with aerobic fitness.
  2. When training loads approach 100% of an individual’s maximum training capacity, HRV starts to reduce.
  3. HRV rebounds after periods of deliberately reduced training (e.g. tapering).
  4. In elite athletes, HRV can remain lowered in the lead up to competition despite achievement of best performances, possibly due to the maintenance of high intensity work during the taper.
  5. Studies that measured HRV in athletes who were already overtrained found both decreased and increased HRV.  Although this has caused confusion amongst researchers, it is likely this is because the athletes’ previous HRV progress during the preceding period is not known, and may have contained a period of initially lowered (sympathetic dominant) HRV followed by adrenal fatigue leading to high (parasympathetic dominant) HRV.
  6. HRV shows quite high natural day to day variation, but weekly and rolling 7 day averages help smooth out the variations. This makes trends more apparent and detection of non-functional overreaching (NFOR) easier, as the chart below from an overtrained athlete in one of the authors (Daniel Plews) previous studies shows.

Training adaptation & HRV

The concept of the Smallest Worthwhile Change (SWC, typically 0.5 x standard deviation) is useful in identifying when the HRV of an individual athlete has changed by more than would be expected by measurement variation alone, and is particularly useful in context of the weekly moving average (baseline).

  1. Time domain indices of parasympathetic HRV (especially RMSSD) have lower variation of measurement than frequency domain measures such as high frequency (HF).  For instance, LnRMSSD was shown to have a coefficient of variation (CV) of only 12% compared to 52% variation using normalised HF power.
  2. Low resting heart rates (below about 55 bpm) in athletes cause the relation between HRV and resting HR to be disrupted by an effect known as parasympathetic saturation.
  3. Criteria for tapering at the elite levels means reduced parasympathetic and / or increased sympathetic activity in the run up to competition may reflect increased freshness and readiness to performance.


The paper’s authors conclude with the following key points:

  • HRV responses are individual and dependent on fitness level and training history therefore regular time based (longitudinal) monitoring is required to get the most out of HRV.
  • Although this review was directed at elites, the HRV response in any athlete with a long training history will likely be the same.
  • LnRMSSD is the most practically applicable HRV index, and is recommended for standardising future HRV studies on athletes.
  • Both daily and weekly / rolling averaged HRV and HR are practically useful measures, and significant changes can be identified using the smallest worthwhile change (SWC).
  • Parasympathetic saturation means it is important to consider both HRV and resting HR for each athlete over a period of time.
  • Optimal HRV response to training overload & pre-competition tapers is not yet fully understood, but increasing HRV values as competition approaches may be a sign of positive adaptation or coping with training load, whereas reductions in HRV in the week/days before pinnacle events may represent increasing freshness and readiness to perform.

What does it mean?

This is all good news for ithlete users, and confirms that we made the right choices for our methods & algorithms 4 years ago, specifically:

  1. LnRMSSD as the main HRV parameter measured in the morning, because it has the lowest variation, and is especially suitable for ultra short measurements of 1 min. (see also RMSSD).
  2. Creating a 7 day rolling average (the ithlete baseline) allows easier identification of trends over the previous week and month (the Weekly and Monthly change numbers on the ithlete chart view). At the sub-elite level, longer term trends (ie 1 month or more) should reflect changes in aerobic fitness.
  3. Ithlete dentifies significant changes in HRV using the standard deviation of LnRMSSD as the smallest worthwhile change (SWC), both relative to the baseline and from one day to the next.
  4. Using statistical methods to identify what is normal / abnormal for an individual over a period of time, rather than making any assumptions about the HRV or HR values of the individual athlete.
  5. Identifying both significant decreases and increases in HRV as potentially signifying maladaptation (non-functional overreaching).  In the past it has been stated incorrectly that ithlete does not detect potentially harmful increases in HRV, but in fact ithlete has 3 algorithms for doing this.
  6. Trying to avoid parasympathetic saturation effects by recommending that athletes with low resting HR perform their measurements in the standing position.
  7. Using combinations of HRV and RR interval (resting HR) to detect normal parasympathetic increases as a result of training & rest vs. abnormal readings resulting from short term adrenal fatigue

Our strategy is to continually improve ithlete and to keep fully up to date with the latest & best research in the field, but it is good to know that we have been on the right track this far.

Original Paper:

Training adaptation & HRV in elite endurance athletes: Opening the door to effective monitoring

by Simon Wegerif

Why Heart Rate Is Higher in Summer

Why Heart Rate Is Higher in Summer

What Is Cardiac Drift and How It Affects Runners

Imagine this scenario: You’re out on an easy recovery run in the summer, and you’re wearing a heart-rate monitor. You’re on an out-and-back course and you’re planning to run for 40 minutes. It’s pretty hot and humid, just a bit more intense than the weather has been in previous days. You turn around at the 20-minute mark, check your heart rate and it’s at 150 beats per minute (bpm).

That’s a bit high for an easy recovery run, but you know you’re running easy, so you assume the heart-rate monitor is just off a bit. You run just as easy on the way back, and right before you end the run you look down and see that you’re now at 162 bpm. Something must be wrong because you know you didn’t run any faster on the return trip, yet your heart-rate monitor shows a 12 bpm increase in the last 20 minutes of the run.

Is your heart-rate monitor broken? Probably not.

What you experienced on that run is a phenomenon called cardiac drift. When you engage in aerobic exercise, your body has to get oxygen-rich blood to working muscles so that the mitochondria in your muscles’ cells can produce energy to contract the working muscles.

Blood is made of cells and plasma, and the plasma is over 90 percent water. When you exercise and start to sweat, you loose some of that water from the blood plasma traveling through your body in order to get oxygen to the working muscles.

When you’re running on a hot day or worse, a hot and humid day, you sweat more than normal. Part of that water coming out of your body to cool you off so that your core temperature stays stable comes from plasma. So the blood in your body has made a subtle shift from a liquid that’s similar in viscosity to water to a liquid that is now a bit more viscous, almost like a watered-down syrup.

Your body’s need for oxygen has not decreased, assuming you’re running the same pace throughout your run, so the only way your working muscles get the same amount of oxygen is if the heart pumps faster, moving this more viscous fluid at a faster rate to make sure enough blood gets to the working muscles.

This brings us back to heart rate. When you start an easy recovery run, you might be at 120 bpm, and if you ran in the fall or the spring in a long-sleeved shirt and shorts on a day when the temperature isn’t too warm or too cold, your heart rate will stay fairly steady over the course of a 40-minute run.

But on a hot, humid day where you are constantly sweating and loosing water, your heart-rate monitor will show a slow rise in heart rate throughout the run via the mechanism above. This is called cardiac drift: the slow increase in heart rate over the course of a bout of endurance exercise. While cardiac drift happens on 20-mile runs in the winter as well since you’re still sweating during that run, the phenomenon can be pronounced even on easy days in the heat of the summer months.

Now you might be thinking, “Great, but what does this have to do with my running?” Actually, not that much, other than the following two things.

First, it’s smart to wear a heart-rate monitor if you are doing a hard workout, such as a threshold or progression run, or track workout, in the summer. This isn’t so much to be informed about the workout paces, but the heart-rate monitor can serve as a leash. Your maximum heart rate should be roughly 220 subtracted from your age. For most workouts, you don’t want to run at your maximum, yet if you’re 40 and you are at 175 beats per minute but still have 20 minutes left in the workout, you might need to stop, or take a five-min recovery jog before you finish the rest of the workout. You don’t want to be up near your max heart rate, but it’s very easy to get close to it in the summer months.

Second, your hydration level can be monitored during the summer by paying attention to cardiac drift. Again, if you’re on a 40-minute easy run and you see a big change in heart rate over the course of the run, such as a difference of 20 to 30 bpm, then you probably aren’t hydrating enough. Water is important, but you should also consume a drink with electrolytes, such as coconut water.

If you wear a heart-rate monitor and are running the same pace and effort on an easy run, and you see a dramatic rise in heart rate over the course of the run, now you know why.