Using heart rate variability to optimise triathlon training

A recent study adds further weight to the purported benefits of training by heart rate variability


Research by a Finnish team suggests that your stress levels – based on an early morning assessment – should also be used to tailor the intensity and duration of that day’s swim, bike and run training to optimise your performance.


Ville Vesterinen of the Research Institute for Olympic Sports and his team examined the effectiveness of using heart-rate variability (HRV) training to prescribe endurance sessions. They concluded that “the timing of moderate- (MOD) and high-intensity (HIT) sessions according to HRV is a more optimal strategy compared to traditional predefined training.”

Heart-rate variability: what it is and why you should measure it

Vesterinen’s team split 40 recreational runners into two groups of 20. After a four-week preparation training period, the first group trained according to an eight-week pre-planned programme including two to three MOD and
HIT sessions each week.

The second group, however, based their eight-week plan and the respective MOD and HIT sessions on their HRV results. Athletes in this group used the Omegawave HRV kit after waking up to measure their readiness to train. After eight weeks, the HRV group realised greater improvements in 3km run performance over the traditional group despite completing fewer MOD and HIT sessions on average – 13 compared to nearly 18.

That performance difference is down to the individualisation and the theory behind HRV training, as Simon Wegerif, founder of HRV training tool Ithlete, explains. “The idea is that small variations in the beat-to-beat timing of the heart reflect the body’s level of stress. Each person has a characteristic amount of variation when they’re well recovered, which decreases when they’re stressed. A daily morning reading is compared to that person’s baseline and used to determine how recovered they are.”

HRV analysis observes the action of the parasympathetic branch of the nervous system, which is responsible for recovery, and broadly describes the variation in HR as we breathe while at rest. Higher variability indicates a well-recovered, calm state; low HRV values suggest chronic stress. Hence, if you wake up one morning and HRV is low, you may be better off swapping your planned high-intensity session for a recovery session instead.

While Vesterinen used Omegawave and Wegerif espouses the benefits of Ithlete, which requires a finger sensor, you can also begin HRV training by simply downloading an app called HRV4Training from HRV doyen Marco Altini. Altini’s system employs optical sensors via your smartphone to give you a reading.


To use HRV to guide your daily session choice, you need to set a baseline. That’s why you have to measure HRV as soon as you wake up (before drinking your morning coffee) and when you’re fit and well, not stressed and ill.

HRV training works best when used with other ‘ready-to-train’ tools, the primary one being Training Peaks (power-meter software), which includes a stress score.


Because your fuelling status affects your recovery and impacts upon HRV readings, limit sessions that could stretch your immune system. For instance, glycogen-depleted efforts.

Heart-rate variability: what it is and why you should measure it

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