I’ve been having a lot of different thoughts running through my mind recently on various topics surrounding HRV and sports training. A lot of what I say today is based on a lot of the research I’ve been reading and comparing it to my personal experience with my own training and that of my athletes. I’ll try and organize it as best I can but it will be pretty random for the most part. Below are several topics that really deserve entire posts on their own however today I will just provide some quick thoughts on each one.

HRV as a predictor of Performance and or Adaptation

–          HRV appears to predict performance in aerobic athletes. I’ve discussed and cited this research in previous posts. However, in a new study by Chalencon et al. (2012) swim performance in elite athletes was related to parasympathetic activity.

 “the delay needed to return to the initial performance level was highly correlated to the delay required to return to the initial HF power level (p<0.01). The delay required to reach peak performance was highly correlated to the delay required to reach the maximal level of HF power (p = 0.02). Building the ANS/performance identity of a subject, including the time to peak HF, may help predict the maximal performance that could be obtained at a given time.”

See the full text here.

–          Prior to the initiation of intensive training, HRV values appear to predict training outcomes, again, mostly in aerobic athletes. Higher HRV values prior to training lead to better improvements in aerobic performance.  See here for more on this.

–          Higher HRV values on game day are correlated to better performance in amateur Basketball players (Di Fronso et al. 2012).

–          There are several factors that affect an athlete’s performance on any given day. By no means am I suggesting that one is doomed to poor performance if HRV isn’t high. I like the saying “psychology trumps physiology every time”. I think it was Alwyn Cosgrove who said that? Regardless, it’s very true. Furthermore pre-game anxiety can provide a skewed HRV result. More research on this needs to be done.

–           At the moment I do not believe that strength/power can be predicted by HRV on a day to day basis based on my experience. It likely play’s a factor but is certainly not determinant.

HRV as a reflection of recovery status

–          I believe this is one of HRV’s greatest attributes. Your level of fatigue after an intense workout or competition will be reflected in your HRV score. This is valuable for planning the weekly training so as not to load the athlete too soon after competition or too much before competition. In my experience this will usually correlate to perceived recovery. You can typically feel this. However, we cannot feel what our athletes are feeling. See Edmonds et al. (2012) for a study on elite youth rugby players for data on this subject.

–          Chen et al. (2011) showed that after an intense strength workout in elite weightlifters strength and HRV dropped. Strength did not return to baseline (or even above) levels until HRV returned to at or above baseline. This is one of the few studies that used HRV in strength athletes. Most coaches/trainee’s should already be aware that 1RM strength will be reduced for the net 24-48 hours after an intense workout but is cool to see that HRV may reflect the actual time period.

HRV as an early warning sign

–          Fatigue is ok, extreme fatigue is not. HRV is probably one of the first warning signs of fatigue. How much fatigue is okay? I think that first HRV will reflect that physical stress is accumulating. However, until performance changes, we likely needn’t change anything. If training is set up appropriately there should be enough rest/recovery for HRV to approach baseline at the end of each week. This will allow for a slower, more steady decline in the trend as opposed to a more rapid and steep decline which indicates excessive fatigue and overload. Planned overreaching should include the monitoring of several training status markers. HRV will respond early.

–          Researchers found that 3 elite tennis players saw significant reductions in HRV values over pre-season training however performance improved (Thiel et al. 2012). HRV alone does not indicate functional or non-functional overreaching. HRV did not correlate to performance markers but did correlate to other training status markers.

Limitations of Weekly or Monthly HRV Monitoring as opposed to higher frequency monitoring

–          Many studies I’ve read pertaining to athletes have measured HRV periodically (weekly, monthly, pre-post training phase, etc). This is much more practical for coaches as daily HRV measurements can be tedious and compliance can be hard to get from athletes. However, day to day measurements are more valuable as they allow the coach to make training adjustments before excessive fatigue builds up. However, if a coach could only use weekly HRV measurements with athletes I think these measurements would best be done the morning after a recovery day. HRV score at rest will provide the most meaningful information about training load/fatigue.

HRV in Elite vs. Non Elite Athletes

–          I have a lot of thoughts on this but will reserve comment until I do some more research on this. In short, I think there is a difference in how HRV data should be interpreted among these groups.

HRV in competitive athletes vs. Recreation lifters/athletes

–          HRV guided training (planning higher loads when HRV is at or above baseline and reducing them when HRV is below baseline) is likely safer and possibly more effective over longer term training. However, I don’t see how this method will work with athletes during shorter term training periods. Overload is required followed by a taper. Conversely, if your training results are not limited by requiring optimal performance at a certain date, HRV guided training will likely reduce risk of injury, illness, nagging join/soft tissue problems, etc. Recreational lifters would certainly benefit from this style of training.

Final thoughts for today

To be clear, the above are all simply thoughts/hunches I’ve been having. These are all incomplete at the moment and require further elaboration. Moreover, my stance on many of these topics are subject to change. My thoughts are limited by my experience and the research I’ve read. There is still a lot of work that needs to be done on HRV to uncover its potential as a monitoring tool in athletes.

References:

Chalencon S, Busso T, Lacour J-R, Garet M, Pichot V, et al. (2012) A Model for the Training Effects in Swimming Demonstrates a Strong Relationship between Parasympathetic Activity, Performance and Index of Fatigue. PLoS ONE 7(12): e52636. doi:10.1371/journal.pone.0052636

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

Di Fronso, S. et al. (2012) Relationship between performance and heart rate variability in amateur basketball players during playoffs. Journal for Sports Sciences & Health, 8 (Suppl 1):S1–S70 45

Edmonds, RC., Sinclair, WH., and Leicht, AS. (2012) The effect of weekly training and a game on heart rate variability in elite youth Rugby League players. Proceedings of the 5th Exercise & Sports Science Australia Conference and 7th Sports Dietitians Australia Update. Research to Practice , 19-21 April 2012, Gold Coast, QLD, Australia , p. 183.

Oliveira, RS. et al. (2012a) Seasonal changes in physical performance and HRV in high level futsal players. International Journal of Sports Medicine. DOI: 10.1055/s-0032-1323720

Thiel, C. et al. (2012) Functional overreaching in preparation training of elite tennis professionals. Journal of Human Kinetics, DOI: 10.2478/v10078-011-0025-x