The Development of Functional Overreaching Is Associated with a Faster Heart Rate Recovery in Endurance Athletes
In 31 triathletes, only the 10 who became functionally overreached showed a faster HRR (+8 ± 5 bpm) during overload, so a faster HRR is not automatically good news
Participants
n=31 experienced male triathletes: 10 control, 21 overload.
Protocol
Tests before (Pre), immediately after an overload training period (Mid) and after a 2-week taper (Post).
Incremental cycling protocol to exhaustion with heart rate, catecholamine release and blood lactate measured.
Functional overreaching (f-OR) defined at Mid as a performance decrease with concomitant high perceived fatigue.
Key Findings
10 of the 21 overload subjects developed f-OR at Mid: performance change −2.1 ± 0.8% together with high perceived fatigue.
Only the f-OR group showed a 99% chance of increased heart-rate recovery (HRR) during the overload period: +8 ± 5 bpm, large effect size.
The same group showed a >80% chance of lower peak blood lactate (−11 ± 14%, large), plasma norepinephrine (−12 ± 37%, small) and plasma epinephrine (−51 ± 22%, moderate); these returned to baseline at Post.
HRR change was negatively correlated with changes in performance, peak HR and peak blood metabolite concentrations.
Authors' conclusions: (i) a faster HRR is not systematically associated with improved performance; (ii) HRR changes must be read in the context of the training phase, perceived fatigue and the performance response; (iii) the faster HRR with f-OR may reflect a decreased central command and lower chemoreflex activity.
Practical Application
In 31 experienced male triathletes (21 overloaded, 10 controls), the 10 who became functionally overreached (performance −2.1 ± 0.8% with high perceived fatigue) were the only group whose heart-rate recovery got FASTER during the overload (+8 ± 5 bpm, large effect, 99% probability), alongside lower peak lactate (−11%) and catecholamines (epinephrine −51%) that normalised after a 2-week taper. So a faster HRR is not automatically a sign of fitness: read it together with the training phase, how tired the athlete feels and whether performance has slipped.
Inference, not tested: the useful pattern is the combination — HRR faster than usual + performance down + high fatigue during a hard block = overreaching, expected to resolve with a taper; the study's f-OR resolved by Post (2-week taper), but a normalisation timeline for HRR itself is not given in the abstract.
Limitations
Male triathletes only; n=31 with 10 f-OR cases — the subgroup that carries the result is small.
Overload was a designed training period; how HRR behaves in self-selected training is not tested.
Magnitude-based inference (chances of change) rather than conventional significance testing.
The abstract gives no detail of the overload's length or how HRR was measured.
How this entry was checked and changed
Content correction 2026-09-27
"Well-trained cyclists" -> 31 experienced male triathletes (10 control, 21 overload), tested on an incremental cycling protocol.
"Detection within 5-7 days", "normalises within 3-5 days of deload", "5-min steady effort (e.g., 260 W), heart rate at 1 min", "week 5 baseline, >5 bpm rule, weeks 7-8, deload week 8" -> not in the abstract; removed. The abstract's timeline is Pre / Mid (after overload) / Post (after a 2-week taper).
Added the abstract's f-OR definition (−2.1 ± 0.8% performance + high fatigue) and the lactate/catecholamine changes (−11%, −12%, −51%) and the authors' three conclusions.
Tier line "mixed→Tier 2-3 (review...)" -> Tier 2-3 (this is a primary study, not a review). Sport "cycling" -> triathlon, cycling.
Full text (checked 2026-10-12)
Participants were well-trained male triathletes (Olympic-distance performance 131 ± 5 min, regional to national level) who had competed for at least 3 y and trained at least 10 h.wk-1 (full text).
The overload was 3 weeks in which the duration of each usual training session was increased by 30%; the taper was 2 weeks with normal volume cut by 40% each week, inside a 9-wk protocol (full text).
Weekly training volume rose from 14 ± 3 h to 19 ± 3 h in the f-OR group and from 13 ± 3 h to 17 ± 3 h in the AF group during overload, against 12 ± 3 h to 12 ± 2 h in controls (full text, Table 2).
HRR was the drop in HR from the end of the maximal incremental cycling test to 60-s of seated recovery on the ergocycle (full text).
HRR in the f-OR group went from 38 ± 11 to 45 ± 11 bpm (Pre to Mid) and was 39 ± 8 bpm at Post; controls went from 35 ± 10 to 34 ± 12 bpm and AF from 40 ± 8 to 42 ± 10 bpm (full text).
Peak power output in the f-OR group was 372 ± 36 W at Pre, 363 ± 36 W at Mid and 378 ± 36 W at Post (full text).
The 11 overload subjects who kept their performance despite higher fatigue were classed as acute fatigue (AF); one subject was classed as non f-OR and excluded, and eight subjects were excluded for injury or personal reasons (full text).
Across all 31 participants, ΔHRR during overload correlated with change in performance at -0.46 and with ΔHRpeak at -0.35 (full text).