Your watch said 178 bpm during the bench press. Your heart was not at 178 bpm. The optical sensor interpreted bar vibration and forearm tension as cardiac signal and reported a number that looked like data. You glanced at it and, correctly, ignored it. Most trainees would not have.
Volume 42 opens Tier 7 — the technology layer — with the honest framing of the wearables category. The global wearables market is multi-tens-of-billions of consumer spending. The literature on what those devices actually measure, where they're accurate, and where they're not, is substantially less commercially convenient. This volume bridges the gap.
Inside this one
- The chest-strap-versus-optical-wrist accuracy differential, mapped to specific training contexts
- The Plews and Laursen HRV framework — rolling-average interpretation, not daily score response
- Sleep tracker reality check — what they get right, what they don't, and the orthosomnia problem
- The non-diabetic CGM landscape — what the commercial marketing is doing and what the evidence supports
- Recovery scores demystified — algorithmic composites versus the subjective-self-report literature
- The optimisation-anxiety meta-problem and the when-to-stop-tracking framework
The standard it is held to
Every factual claim in this volume names its source, and every claim carries a confidence grade — settled, strong, emerging or contested. Where the evidence is thin, the text says so. How it’s made, in full → · What we’ve got wrong →