Overtraining leads to injury, illness and diminished performance. The body can endure just so much continual physical stress before it begins to break down.

So how do you know when to train and when to rest?

The answer is heart-rate variability (HRV), which measures the time-gap between your heartbeats when you’re resting. The heart, in fact, speeds up when you inhale, and slows down when you exhale. The difference is known as heart-rate variability. A healthy, well-rested body will produce a wider gap than a stressed out, over trained body.

HRV in sports training RR intervals

Heart rate variability is measured by calculating the time between R wave peaks on an ECG trace

Today, new technology such as ithlete allows athletes to more accurately monitor their HRV. In just 60 seconds, the ithlete app provides an independently validated measurement of your HRV and resting heart rate, graphs of your results, stores your personal information, and allows for daily testing comparing your weekly and monthly results. As such, ithlete warns you if HRV worsens, indicating an autonomic imbalance and the need for additional rest that day, or an easy rather than hard workout. As you would expect, autonomic balance, as measured by HRV, is maintained following an aerobic workout; however, after an anaerobic workout, autonomic balance is slightly disturbed until the body recovers. In addition, athletes who maintain a good balance of autonomic function, as indicated by HRV, perform better.

HRV in sports training

The number presented by ithlete is on a scale from 1-100 and represents your HRV. Unlike resting-pulse, a higher HRV number is better. It’s not a percentage though, and an ultra-fit person could go over 100.

The ithlete number is created from a standardized measurement of parasympathetic heart rate variability (lnRMSSD). Increased parasympathetic activity enables recovery.

Factors that decrease HRV:

  • Physical stress from intensive training
  • Mental stress ie work, life stress
  • Insufficient recovery, rest & sleep
  • Poor diet (eg. too many refined carbs, not enough fruit, vegetables, fish)
  • High altitude, dehydration, jetlag
  • Excessive alcohol, hangovers
  • Smoking
  • Illness, inflammation and disease
  • Increasing age

Factors that increase HRV:

  • Recovery, rest and sleep
  • Higher aerobic fitness levels
  • Relaxation (including social activities, listening to music, yoga & breathing exercises)
  • Good nutritional choices (especially, fish, fruits & vegetables). A recent study on the benefits of the Mediterranean Diet found increased HRV to be closely associated with improved heart health

Athletes are likely to have average scores of 65 or higher, with endurance competitors in the 80s to mid 90s on the ithlete scale.

by Simon Wegerif