In my first post on HRV I highlighted what I thought to be HRV’s most promising attributes. I would like to add another to that list;

HRV may be able to tell you when you’re at a higher risk of injury.

After one of many e-mail based discussions I’ve had with Simon Wegerif  (creator of iThlete), he  happened to put this idea in my head. I told him about the study we are trying to run here at Cal U where we will compare HRV guided training vs. pre-planned training in off-season collegiate football players. We are looking to see if one method is better than the other for increasing strength. Simon mentioned that we should consider looking at illness and injury among the players as well. He followed up this suggestion by mentioning some research done by a veterinarian who found a correlation between low HRV scores and increased injury rates among race horses.

I immediately began scouring several databases for any research to show HRV as a predictor for injury potential. My search proved to be futile as nothing of note came up. I was however, able to get my hands on the article on race horses Simon had mentioned.

In a nutshell, Dr. Christine Ross monitored the HRV of 16 competitive race horses, all of which were in training. Of the 16, 13 had HRV readings that were associated with pain, fatigue, illness or injury. It was stated that even though the horses appeared healthy and energetic, they were considered “at risk” based on their HRV. There were no outward signs or symptoms to suggest these horses were currently sick or hurt. Within 3 months, 12 of the 13 at-risk horses got injured or sick requiring veterinary intervention and cessation of race training. (Message me if you would like to see the article)

The results of Dr. Ross’ findings are staggering. Can HRV detect the same issues with humans?

Naturally, I began thinking of all of the injuries I’ve had over the years from football, hockey, lifting, etc.

Since I’d only been measuring my HRV for the past 7 months I focused on injuries since mid-August. I just so happened to have injured myself once during this time period. Through my training log I was able to pinpoint the exact day. It was Oct. 11, 2011. During a set of squats with about 60% of my 1 rep max on the bar, I pulled a muscle in my lower back. This injury kept me from lifting for about a month. I cross referenced that day with my HRV scores. Sure enough, my HRV was extremely low at 66.4 and my heart rate that morning was 83.8 beats per minute. Keep in mind that at this time I was simply taking my HRV score for observational purposes and not using it to guide or manipulate my training. In the image below you can see the large downward deflection in HRV from early October when I hurt my back.

Back Injury in October HRV Score

Typically only conditioning workouts or illness cause my HRV to drop so dramatically as I explained previously in this post. In this instance, I had not performed a conditioning session nor was I sick in any of the days prior to the injury. What caused such a significant drop in HRV? Well, that weekend I was in Ohio for my grandmother’s funeral. My best guess is that the emotional stress in addition to the stress from travelling caused this drop.

I wish I had more than animal research and anecdotal experience to share on this topic. I will keep my eyes peeled for any further evidence on this topic. I’m sure coaches who have been monitoring the HRV of their athletes would be able to provide some better insight on the matter.

If HRV happens to be an accurate indicator of a heightened risk of injury (among many of its other purported attributes), would you be monitoring your HRV? If you are a coach, would you want to know the daily HRV scores of your athletes? If one of your starting football players was showing poor HRV scores on a day where you were going to have them perform tackling drills in practice, would you have him sit out? How would you manipulate strength and conditioning training based on your athletes HRV scores?

I hope to shed some light on this topic with the research we are trying to do here at Cal U. I want to monitor the HRV in both training groups and observe what may happen to an athlete in the pre-planned group who may be having low HRV scores. Though we will be measuring strength, we can still observe if and when athletes get sick or hurt.

I’m happy to report that we recently received a sample HRV device from Polar (the RS800 Watch). Our fingers are crossed that we can work something out to get several more for the study!

Have a good weekend!

I’ve been monitoring my HRV for almost 7 months. Throughout this time I did not use HRV to guide my training but rather have just observed how my HRV scores responded to my regular routine. My regular routine consisted of training upper body and lower body twice/week. Monday was Squat, Tuesday was Bench, Thursday was Deadlift, Friday was Incline or Overhead press. I’d follow each main lift up with assistance work.  Today I’ll disclose what I’ve learned from my observations and how I will start to use HRV to vary my training.

Observations:

I’ve noticed that conditioning sessions (intervals on steps) affect my HRV the next morning much more than heavy strength work outs. This is obviously because I had been performing no conditioning work within the last year. However, after performing the conditioning sessions consistently over several weeks (one time per week) I noticed an overall improvement in HRV and I no longer experience massive drops the morning after the conditioning session. This is a prime example of HRV reflecting adaptation to what initially was an immense stress on my body. To give you an example, the morning after my first stair interval workout my morning heart rate after waking was 84 bpm and my HRV was 66. My typical morning heart rate is around 60 bpm (give or take) with HRV averaging almost an 80. If I miss a few weeks of conditioning, the next time I do them again my HRV plummets (I have deconditioned) .

We run 67 steps that look very similar to those above for between 30-50 rounds depending on the day.

I’ve recently began performing 20 minute light aerobic recovery work on off days to see what would happen. I found that when I do these consistently my HRV scores show smaller fluctuation from day to day. No surprise here.

I rarely get sick, but when I do, I see a significant drop in HRV. This winter there was a morning where I woke up (from a terrible night’s sleep) with a head cold, stuffed nose, etc. My morning heart rate was 92 bpm and my HRV was 56. This was my worst ever result. Needless to say I did not train that day. In the past I would often debate in my head if I should train anyway. Actually seeing how much it affects my adaptability to training was very eye opening.

I have not experienced any significant changes in HRV from minor muscular injuries. However, I do notice a decline in HRV after a few days if the injury causes me to stop training. Furthermore, I’ve noticed that HRV stays higher on average when I am consistently exercising over time and am more active throughout the days. When I’m at Cal in the weight room every day moving around and training athletes, my HRV is tpyically higher compared to when I go home for a month over Christmas and sit around too much. Within a few days of inactivity I’ll typically see HRV decline somewhat.

I’ve noticed lower HRV scores during times of travel and sleeping at places other than my own bed. I drove 4 hours from Pittsburgh to my folks place in Cincinnati and slept there for 2 weeks. The first two mornings my HRV was noticeably lower than normal. I found this to be surprising as I didn’t feel that the travel was too stressful, nor did I think that sleeping in a different bed was too stressful. This happens pretty much every time I travel.

I have not experienced a correlation with higher strength levels on days where HRV is above baseline. I’m going to elaborate on this more in a different post as I have a lot of thoughts on HRV and performance prediction as well as more research to share regarding this.

How I plan on using HRV to manipulate my training loads:

– I will change from lifting on Mon-Tues-Thurs-Fri , to adjusting to an every other day format. This is because my HRV scores on Tuesday and Friday are always lower due to Monday and Thursday training sessions. Having a day off between workouts allows for an increase in HRV on all training days which hypothetically allows for better adaptation. We’ll see how it affects my training.

– On days where HRV scores are above 80, I will perform a higher volume of work over 90% of my 1 rep max. The idea here is that since I’m more adaptable to training, I will place a greater stress on my body. For example I’ll perform 3 sets of 3 above 90% whereas I typically would do only 1 work set over 90%.

– If HRV is around baseline (77-80) I will perform a lower volume of work over 90% such as 2 sets of 2.

– Finally, if HRV is below baseline I will avoid working over 80%. I typically deload after every 3 week cycle but will no longer be doing so. I will simply reduce volume and intensity on days where HRV is low. I will deload only if and when I feel I need it based on HRV scores, performance markers (strength) and how my joints feel.

For now, this is the plan. The reps and percentages are not set in stone. The main idea is that I’ll be training with high intensity and volume on high HRV days; high intensity and moderate volume on baseline HRV days; deload on low HRV days. If I set any personal records in the gym on Bench, Squat or Deadlift I’ll know the plan is working. I haven’t hit a PR since Canadian Nationals in 2010. This is partially due to injuries and partially due to dropping 20 lbs of body weight. I’ll stop now with the excuses.

In my next post I’ll give an update on the research we’ll be doing here in the weight room with HRV and football players. I’ll also elaborate on my thoughts on HRV and its ability to predict performance.

Thanks for reading.

If you’ve been following my discussions you’re probably curious about how one goes about monitoring their HRV. Today I’ll inform you of how I monitor mine as well as a few other options available. I strongly suggest reading Part 1 and 2 of my HRV discussion before reading this if you haven’t already.

If you have $30,000+ lying around then you can buy yourself an Omegawave. This device is used by organizations within the NFL, NCAA, Olympics, Pro Soccer leagues in Europe, etc.

Here is a demonstration of NFL players having their HRV measured on the Omegawave prior to training camp.

Assuming that dropping 30 g’s is unreasonable for you there are some other options.

I personally use an app called the iThlete that is compatible with both ios and android. The iThlete requires a heart rate strap and a small ECG receiver that you plug into the headphone jack.

To measure HRV you simply plug the ECG receiver in, strap on the heart rate monitor and press the start button on the app. You should measure HRV in the morning after you wake up. This will give you the most accurate score since you’ve yet to encounter any stressful events for the day. The app will measure your heart rate for about a minute and provide you with your heart rate score in beats per minute (bpm) and HRV. It provides the HRV score through a calculation based on the time interval between each beat. You do not see the raw data but are just given a score. The higher the score for HRV, the more recovered and rested you are (parasympathetic dominant). Here is a screen shot from my score this morning.

HRV and Heart Rate score this morning

*To give you an idea of my HRV scores anything between 77-80 would be good. Anything above would be exceptional recovery and anything under would indicate insufficient recovery. This morning my resting heart rate was 63bpm and my HRV was 81. This is a great score for me.

Now here is where the app gets really cool. If you select the chart button at the bottom of the screen you see a chart of your HRV trends over time. You can see a chart displaying all HRV scores ever measured, all HRV within the last 3 months, 1 month or week. Here is a picture of mine.

Upward deflections represent higher scores (increase in parasympathetic activity) and the downward deflections represent lower scores (decrease in parasympathetic activity). Green lines tell you that intense training will be well tolerated, amber lines caution you not to go overboard with your training and red lines tell you to take a recovery day.

The massive red downward deflections you see on the chart all occurred the day after I performed intense conditioning sessions. These were so stressful to my body because I’ve been training for powerlifting for the past few years and have done little conditioning. My body was not adapted to that type of training and clearly reflects this in my HRV scores. The most recent drops in HRV (shown in late December) actually show my adaptive reserves plummet while getting sick with a head cold. The first day I started to feel the cold coming on my heart rate was 78bpm and my HRV dropped to 68! The next day (the worst day of my cold) my morning heart rate was 92 and my HRV was 56! Needless to say I did not train on those days.

The last image I’ll show you from the app is the graph you can view.

This displays all of your HRV scores ever taken. You can scroll down for more scores. Additionally you can e-mail your data to your coach or anyone who may be overseeing your training allowing them to make any necessary adjustments in your training.

Another app exists called the Bioforce HRV App. Bioforce is compatible with ios and Android. This was designed by former NFL strength coach and current MMA strength coach Joel Jamieson. This app functions similar to the iThlete as it is manufactured by the same developer. BioForce differs from ithlete mainly in measurement duration (2.5 minutes vs 55 seconds), preferred position (supine vs. seated or standing).

I’ll also mention that Polar has heart rate monitor watches that can also provide HRV scores. The RS800 watch from polar is a valid instrument for collecting RR intervals and has been used quite a bit in research. However, be prepared to manually export your data from the watch to software that can analyze the data. This is not the most convenient option but will provide very accurate data.

If you’re interested in buying an HRV device I suggest you do your research on each one and find which best suits your needs.

In my next post I will discuss what I’ve learned from monitoring my own HRV for the past 7 months or so. I’ll include details on how I’ve altered my training structure because of it and give examples of how I manipulate my training day to day based on my HRV score. Additionally I’ll discuss non-training related events that have sapped my HRV scores that really taught me about how my body responds to things such as travelling, poor sleep, etc. I’ll include anecdotes about when my HRV scores were exceptionally high and what I think may have influenced them.

Thanks for reading.

In today’s post I want to provide some research to support my bold claims about the effectiveness of HRV. The following research studies have been summarized to make more reader friendly as to not bore anyone who isn’t too interested in research methods, statistical analyses and so on. I have listed the citations for each study at the end for anyone interested in reading the research themselves. Additionally I have each one as a .pdf so just request a copy and I can send it.

HRV Reflecting Recovery status:

Chen et al (2011) found that HRV drops significantly within 24 hours of recovery from a high intensity strength workout in elite male competitive weightlifters and returns to baseline by 72 hours. Weightlifting performance was recovered exceeding baseline and reaching maximum at 72 hours thus showing a significant correlation between HRV and recovery.

Iellamo et al (2004) studied male rowers from the Italian national team during preparation for the world championships. The researchers found that from 50% to 100% of training load, there was a significant decrease in HRV and increase in sympathetic tone. As training reduced to 50% during the World Championships, HRV returned to base line and a return of autonomic indices to previous levels was seen. They concluded that monitoring of HRV can provide useful information to assess the dynamics of training through a simple non-invasive approach.

Pichot et al (2002) set out to test HRV as a practical and reliable marker of fatigue during training. 6 untrained subjects showed improved HRV during intense training. During overload training an increase in sympathetic activity was seen with a corresponding decrease in HRV. During a recovery week there was a sudden and significant rebound of parasympathetic activity and increase in HRV.

Research demonstrating better adaptation to training when HRV scores are high:

Hedelin et al (2001) found that endurance athletes who improved Vo2 max consistently showed higher HRV scores compared to athletes who showed deterioration in aerobic performance; of which showed lower HRV scores.

Kiviniemi and colleagues (2007) split 26 fit males into an HRV guided training group, a pre-planned training group and a control group. The HRV group was given intense training if HRV was the same as baseline or higher while moderate training or complete rest was given with significant drops in HRV. The pre-planned training group followed a pre-planned program typical of most endurance athletes. The results showed that HRV guided training produced a significantly greater increase in maximum velocity running compared to the pre-planned training group.

Kiviniemi et al (2010) conducted a very similar study to their 2007 work but in this case HRV groups were split in to a female group and a male group. The methodology was the same as the 2007 study where HRV groups performed training based on HRV scores while the pre-planned training group had pre programmed training. The results showed that men in the HRV group had greater maximum velocity than the pre planned group consistent with 2007 results. The HRV female group saw no significant increase in maximum velocity over the pre planned group. What’s interesting is that the HRV female group was able to improve their fitness to the same levels of the pre planned group with a lower weekly training load (fewer high intensity training days).

HRV predicting performance:

Cipryan et al (2007) showed that male hockey players have higher rated performances from their coach when HRV is high and that any drops in HRV correspond with a lower rating of performance. Of the sample players, the one with consistently low HRV was rated the lowest in performance. This demonstrates a strong correlation between HRV score and performance.

Devils Advocate

I should mention some research that shows HRV’s inconclusive ability to monitor training in attempt to be impartial. Bosquet et al (2008) performed a literature review to determine if HRV is effective at monitoring over-reaching. They determined that HRV should be used along with other known indicators and symptoms of overtraining to be meaningful. Additionally, Nigam (2010) concluded that HRV is more accurate than heart rate but not enough research exists to use either as a sole indicator of overtraining.

Edit: For more research on HRV see this post.

My Thoughts

It’s pretty evident that HRV can reflect recovery status. This has been demonstrated in both aerobic and strength athletes several times. This quality alone makes HRV worth monitoring if you are serious about your training. I’d like to see more research showing correlations with HRV and performance. Does having high HRV mean we can perform better on that day? Does low HRV doom us to substandard performance? The study on Hockey players is the only paper I found that would suggest this. I personally am not convinced. More research needs to be conducted on strength athletes in particular as this it is greatly lacking.

Grabbing the bull by the horns

Rather than complain that not enough research exists I thought I’d take matters into my own hands. I have proposed a research study to a researcher here at my university with the support of Bobby (the head strength coach) and Dr. Brian (Director of Athletic Performance) to compare HRV guided training vs. pre-planned training in collegiate football players this offseason. We will test 1 rep maxes in the big lifts before and after and see which group made the greatest improvements. This is basically copying Kiviniemi’s design except we are measuring strength performance in football players as opposed to running velocity in endurance athletes.

I’m happy to say that the department of athletic performance are all on board to conduct this research though there is still much to be done in acquiring valid instruments, getting approval from the IRB and so forth. Fingers are crossed that we can get it done. This is not part of my graduate program as I’m completing a course work based Master’s rather than a thesis based one. This research will be entirely out of personal interest on behalf of myself and the participating staff at the school.

In my next post I will display nearly 7 months worth of data from my own personal HRV scores. It will be much more interesting than this post I promise.

Thanks.

References

Bosquet, L., Merkari, S., Arvisais, D., Aubert, A.E. (2008) Is heart rate a convenient tool to monitor over-reaching? A systematic review of the literature. British Journal of Sports Medicine, 42(9): 709-714.

Chen, J., Yeh, D.,  Lee, J., Chen, C.,  Huang, C.,  Lee, S., Chen, C.,  Kuo, T., Kao, C., & Kuo, C. (2011) Parasympathetic nervous activity mirrors recovery status in weightlifting performance after training. Journal of Strength and Conditioning Research, 25(6):  1546-1552

Cipryan, L., Stejskal, P., Bartakova, O., Botek, M., Cipryanova, H., Jakubec, A., Petr, M., & Řehova, I. (2007)  Autonomic nervous system observation through the use of spectral analysis of heart rate variability in ice hockey players.  Acta Universitatis Palackianae Olomucensis. Gymnica, 37(4): 17-21.

Hedelin, R., Bjerle, P., & Henriksson-Larsen, K. (2001) Heart Rate Variability in athletes: relationship with central and peripheral performance. Medicine & Science in Sports & Exercise, 33(8), 1394-1398.

Iellamo, F., Pigozzi, F., Spataro, A., Lucini, D., & Pagani, M. (2004) T-wave and heart rate variability changes to assess training in world class athletes. Medicine & Science in Sports and Exercise, 36(8): 1342-1346.

Kiviniemi, A.M., Hautala, A., Kinnumen, H., & Tulppo, M. (2007) Endurance training guided by daily heart rate variability measurements. European Journal of Applied Physiology, 101: 743-751.

Kiviniemi, A.M., Hautala A.J., Kinnunen, H., Nissila, J., Virtanen, P., Karjalainen, J., & Tulppo, M.P. (2010) Daily exercise prescription on the basis of HR variability among men and women. Medicine & Science in Sport & Exercise, 42(7): 1355-1363.

Nigam, A.K. (2010) Resting heart rate and overtraining in athletes. International Referred Research Journal, 2(21): 38-40.

Pichot, V., Busso, T., Roche, F., Gartet, M., Costes, F., Duverney, D., Lacour, J., & Barthelemy, J. (2002) Autonomic adaptations to intensive overload training periods: a laboratory study. Medicine & Science in Sports & Exercise, 34(10), 1660-1666.