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Detecting and Avoiding Overtraining Part I: Heart Rate Variability, A Useful Tool?

By Lee Gardner and Walter F. DeNino

As the racing season is about to start, you may want to consider what worked and what did not from the season past. One of the most common training errors we see athletes make is to overtrain. As such, we think it is a perfect time to explore the topic of overtraining and how it might be detected before it's too late. After all, that's the key: avoiding overtraining in the first place. Triathletes, by nature, are a hard-working and highly motivated group of people. Independent of talent, far too many athletes incorrectly think that relentlessly increasing training volume and intensity will lead to improved results. More is better, right?

What many find, eventually, is that the body can only handle so much training. At some point, fatigue sets in and it's very difficult to recover from this fatigue. In European academic circles of sport science, a vocabulary a bit different from ours has coined the terms "over-reaching" (overtraining), functional over-reaching (FOR), non-function over-reaching (NFOR) and overtraining syndrome (OTS). As you can probably guess, these terms represent a spectrum of increasing fatigue. Functional over-reaching or "FOR" is what the athlete should be doing during the training process, that is applying varying dosages of stress followed by recovery, hence functional.

As a coach plans an athlete's training program, there should be tolerable increases in volume and intensity so as to apply FOR. However, if the athlete is exposed to a quantity of volume or intensity that he or she is repeatedly not allowed to recover from, then the athlete may move along the spectrum to NFOR and, ultimately, OTS (the "s" in OTS is for syndrome, simply meaning that there is not only diminished performance capacity but also physiologic and psychologic signs and symptoms of being overtrained). It is the coach's responsibility, in concert with the athlete, to prevent slipping into the NFOR and OTS end of the spectrum.

Commonly, parameters such as resting heart rate, sleep quality and diet are used to gauge an athlete's state of recovery (more on those later). More recently, heart rate variability (HRV) has been investigated as a potentially important indicator of the same. The basis of this is rooted in the concept that catecholamine levels are altered during activity and at rest in the overtrained state. Catecholamines are compounds produced by the body in response to stress that, among other things, effect heart rate. Think of them as chemical messengers that are released during times of stress to signal the heart to pump faster or the blood vessels to constrict or dilate.

In addition to a natural tendency to overdo it when it comes to training, triathletes crave innovation and new toys and gizmos to help them cross the finish line faster. It's no surprise, then, that there are devices on the market to measure speed, temperature, heart rate, percent body fat, resting metabolic rate, power, blood lactate, altitude, the list goes on...and, yes, heart rate variability.

After conducting a thorough review of the current literature, it was obvious that, like many other aspects of endurance performance, there were few published studies. Moreover, the available studies were either poorly designed or had small numbers of subjects. However, the most comprehensive report on HRV came from a group at the University of Montreal in Canada. This paper, a systematic review, essentially incorporated all previous studies (of highest quality) involving athletes that were intentionally over-trained and measures of HRV. All told, this paper included up to 34 studies and 159 subjects. The conclusion of the review, published in 2008 in the British Journal of Sports Medicine, is that short term overtraining (FOR) resulted in moderate increases in HRV, however, these alterations were of a magnitude that fell within the range of normal physiologic variability. The take home message here is that while we might be able to measure HRV in a research setting, or even in the field, the magnitude of the alteration is clinically insignificant or of little practical use.

So where does this leave us? What indicators of overtraining, or "over-reaching" can a coach use to accurately detect when an athlete is on the brink? Stay tuned next week for our next article in this series as we explore the alternatives.

trismarterLee Gardner is a triathlon coaching associate with  as well as a USA Triathlon Certified Level 1 triathlon coach. Walter F. DeNino is the president and founder of Visit to learn more about their personalized coaching options such as Tri4Life and Tri2Lose as well as innovative Eat2Win sports nutrition services. Contact or call 917.825.1451 for more information. strives to provide the highest quality internet-based triathlon coaching and sports nutrition services for the everyday triathlete and novice. These services are based on an understanding of the sport and tailored to the expectations and needs of each and every client. Our services address every aspect of triathlon preparation: Tri4Life personalized coaching, Tri2Lose weight loss and Eat2Win sports nutrition. At, we celebrate the journey along with our clients from start to finish.

Bosquet L et al. Is heart rate a convenient tool to monitor over-reaching? A systematic review of the literature. Br J Sports Med 2008

Lehmann M et al. Training-overtraining: influence of a defined increase in training volume vs. training intensity on performance, catecholamines and some metabolic parameters in experienced middle and long-distance runners. Eur J Appl Physiol 1992

Hooper SL et al. Hormonal responses of elite swimmers to overtraining. Med Sci Sports Exerc 1993

Baumert M et al. Heart rate variability, blod pressure variability, and baroreflex sensitivity in overtrained athletes. Clin J Sport Med 2006