HRV Scientist: The NEW HRV Metric That Could Help Runners Over 40 Keep Improving

In this episode of The Endurance Lab, I sit down with Dr. Greg Grosicki, Staff Research Scientist at WHOOP, to explore the science of HRV and HRV-CV and, more importantly, how runners can actually use these metrics to make smarter training decisions.We break down why higher HRV is generally better while lower HRV-CV is generally better, why your seven-day HRV trend can tell you something very different from today's reading, and what different combinations of HRV and HRV-CV may reveal about recovery, adaptation and accumulated training stress.We also get practical. What should you do when today's HRV is suppressed but you feel great? When should HRV actually cause you to change a planned interval workout? What happens to HRV-CV during a hard training block or taper? And can these metrics help runners recognize when they're adapting well versus drifting toward excessive fatigue?For runners over 40, we also explore an especially interesting question: how do HRV and autonomic stability change as we age? Greg discusses research showing age- and sex-related differences in HRV-CV, what may happen after around age 40, and whether exercise and fitness could help attenuate some of the age-related decline in HRV.In this episode, we cover: what HRV-CV actually measures; HRV vs HRV-CV; why HRV should be compared to your own baseline; whether wearable HRV measurements can be trusted; heat stress and HRV; daily HRV vs seven-day trends; four HRV/HRV-CV training scenarios; when to train hard versus back off; HRV-CV as a marker of adaptation; what happens during overload and tapering; HRV recovery and resilience; how HRV-CV changes with age; autonomic aging; and how Zone 2 and high-intensity training affect HRV.➡️ Join The Endurance Lab Inner Circle on Telegram👉 https://t.me/TheEnduranceLabInnerCircle🔥 FIND YOUR TRUE ZONE 2 WITH TYMEWEARTymewear Vita Pro measures your breathing in real time to identify your individual physiological thresholds and help you train at the intensity you actually intend to train at.➡️ Endurance Lab listeners SAVE $100 OFF the Tymewear Pro Training membership Code: E-LABTW26👉 https://www.tymewear.com/E-LABTW26➡️ Listen to my conversation with TimeWear founder Anar Larson: 👉 https://open.spotify.com/episode/5sz25EZjGUHoGSaA38nHwM➡️ Previous Endurance Lab HRV episode with Dr. Marco Altini👉 https://youtu.be/D6ZPuaMaEgs➡️ HRV-CV research discussed in the episode:Grosicki et al. — “Heart rate variability coefficient of variation during sleep as a digital biomarker that reflects behavior and varies by age and sex”👉 https://pubmed.ncbi.nlm.nih.gov/41309064/Chapters00:00 Higher HRV vs lower HRV-CV00:30 Using HRV to guide running training02:21 What is HRV-CV?08:57 The science behind HRV-CV12:03 How new is HRV-CV?13:48 Dr. Greg Grosicki’s journey to WHOOP19:31 What is WHOOP?20:43 Sleep, recovery and strain27:42 How WHOOP uses recovery data31:04 Inner Circle: Can you trust HRV from sports watches?35:15 How heat stress affects HRV37:06 Daily HRV vs 7-day HRV vs HRV-CV39:59 Two runners with the same HRV — but very different recovery44:09 Four HRV + HRV-CV training scenarios47:47 The HRV-CV warning sign49:55 How to use HRV to decide whether to train hard53:28 When good HRV can still be misleading54:14 Is HRV-CV a measure of adaptation?55:16 Why low HRV-CV isn't always good57:19 What happens to HRV-CV during hard training?58:25 How high is too high for HRV-CV?1:00:49 What should happen to HRV-CV during a taper?1:01:30 HRV recovery and resilience1:03:30 What happens to HRV-CV as we age?1:05:44 Autonomic aging and HRV1:08:03 How training can improve HRV and HRV-CV