I’ve been reviewing my HRV trends over the last few weeks to analyze how my body is handling my current training set-up. I’ve been noticing smaller drops in HRV the day following a heavy workout (sRPE9). In some instances I’ve seen a small hike in HRV the following day. Today I will provide a few thoughts on what may be happening as well as some thoughts on things to consider when analyzing your data.

It’s been demonstrated in the research quite clearly that HRV reflects recovery status in both weight lifters and aerobic athletes. Therefore, it’s reasonably safe to say that your HRV score the morning after a workout is reflecting how stressful the workout was. However, it’s extremely important to consider other variables that can affect recovery (other stressors). So taking this into consideration, HRV score reflects not so much the stress of the workout, but rather how well your body was able to respond to it since the cessation of yesterday’s training session (assuming the workout was the biggest stressor of the day).

Let’s say you performed an intense workout that you rated a 9 out of 10 on an RPE scale. The following day your HRV score will depend on the following key variables;

Nutrition: Did you provide the resources for your body to recover from the session? Proteins for structural repairs of damaged muscle fibers, fats for overall calorie intake and hormonal support and carbohydrates for glycogen re-synthesis. Was overall calorie intake sufficient? 

Purposeful Rest/Relaxation: Following the workout did you start the recovery process by relaxing, hot shower, etc.? This will allow the parasympathetic nervous system to get the recovery process underway.

Compounding stress: In contrast to the above, did you add further stress to your body? How physically active were you? What stressful events occurred and how bad were they?

Sleep: How restful was your sleep? How many hours? Were there disturbances?

Aerobic Fitness/General Physical Preparedness: The more aerobically fit you are, generally the better your HRV will be. The higher your work capacity, the more stress your body can handle. In my experience, in effort to increase performance in a given quality, it’s important to consider the overall fitness of the individual as this can limit and effect recovery, training frequency, volume, intensity, etc.

Familiarity of the Training Session: What type of workout was it? Have you performed this workout recently with similar loads? In other words, has your body adapted to the workout structure which therefore reduces the stress on the body?

I would like to elaborate on the last point since the above are pretty self-explanatory. When considering HRV response to a training session, it’s important to evaluate if you are introducing a new stress to the body via new workout structure, type and familiarity of work (aerobic, anaerobic, running, rowing, resistance, etc.). It’s been my experience that a new workout structure or unfamiliar training will create a larger drop in HRV. This is obviously because your body is not accustomed to the type of work and must work hard to adapt and recover. For example, the first time I performed a conditioning session this past year my HRV dropped immensely. However, each conditioning session thereafter provoked less and less of an HRV drop. HRV reflected my progressive adaptation to the stress. Even though the workouts may still have been perceived as hard, the body is familiar with the stimulus and homeostasis is quickly restored.

Some follow up questions based on the above discussion;

1. Is the workout still effective if it does not provoke a marginal stress response (drop in HRV)?
2. Should we use HRV as a guide to adjust and make changes to training structure to avoid staleness/plateau (periodization)?

In addressing question 1, it’s important to first evaluate training progress. Check your workout log. Are you still getting stronger/faster/running further, etc (whatever your training goal is). If the answer is yes, continue. Other factors and adaptations are obviously taking place.

In response to question 2, we need to carefully examine all of the above factors that affect an HRV score. If your nutrition is on point, you are reducing compounding stress, sleeping well and so forth, we can assume that the following day’s HRV is a reflection of your response to the training session.

If you’re experiencing a plateau it’s time to consider altering training. If you are a strength athlete you have a few options. Adjust volume or intensity. Adjust training sequence/frequency. Make adjustments to the lifts themselves. For example, add a pause to your bench or take it away, rotate assistance lifts, add or remove an exercise. Obviously only one major adjustment is needed. Evaluate progress, keep track of HRV trends and see if that made a difference. It’s also important to consider that training progress in more advanced athletes/lifters is non-linear. Therefore, don’t make drastic changes at the first sign of plateau. It’s okay to repeat workouts. Use your judgement on if a change is needed.

I will continue with my current training structure and set up to see if progress continues or stops and if HRV trends change or stay the same. Once I can evaluate more of my data I’ll write up a report.