PHYS-27 · Principle
My HRV dropped after a hard block. Am I overtrained?
Unlikely from that alone. A dip that rebounds with rest is normal; overtraining is a lasting performance drop found by ruling out other causes, and HRV did not reflect overreaching.
How the body works, agreed across the reviews below; a study entry shows what one experiment measured.
Practical Application
My HRV dropped after a hard block. Am I overtrained? Unlikely from that alone. A dip that rebounds with rest is normal; overtraining is a lasting performance drop found by ruling out other causes, and HRV did not reflect overreaching.
Mechanism
Functional overreaching is a short-term performance drop that, after recovery, gives an improvement; out of balance, the drop lasts longer with no rebound (non-functional overreaching); overtraining syndrome is prolonged maladaptation; the two late states are very hard to tell apart and are separated by clinical outcome and exclusion (REF-206).
In 12 studies of trained to professional endurance athletes, lower maximal power and heart rate, a lower heart rate at a fixed submaximal load, higher RPE, faster heart-rate recovery and mood scores reflected functional overreaching; VO2max and HRV changes did not (REF-207); in a meta-analysis of 24 studies resting HRV was largely unaffected while post-exercise HRV rose as it does with positive adaptation (Bellenger 2016).
Planning grew from Selye's stress model, which treated training stress as directly setting the size of adaptation; stress science has since moved on (Kiely 2018).
Common misreading
"HRV down means overtrained"; "no gain without getting overreached"; "overtraining is a blood test result".