I have three DEXA scans on the same scanner at twelve-week intervals, fasted, same time of day.
I suspect the usual explanation for this is wrong, or at least incomplete.
I am aware this may have a boring answer. I would still like the boring answer stated clearly.
What is actually going on here, physically?
Compound movements give the most stimulus per unit of recovery, which matters more when recovery is the limiting resource.
Around ten hard sets per muscle group per week is the region where most of the retention benefit is realised; more produces diminishing returns and, in a deficit, a recovery cost.
| Method | Measures | Sensitive to | Least significant change |
|---|---|---|---|
| DEXA | Three-compartment by attenuation | Hydration, positioning | ~2–3 % regional lean |
| BIA (consumer) | Impedance, modelled | Hydration, food, temperature | Not usable at this timescale |
| Air displacement | Two-compartment by density | Lung volume, hair, clothing | ~1–2 % fat mass |
| Tape and scale | Circumference, mass | Technique | Surprisingly usable as a trend |
The part that matters: two sessions per muscle group per week outperforms one at matched volume in most of the published comparisons, mainly through better session quality.
Training-to-failure comparisons show similar hypertrophy with substantially greater fatigue when sets are taken to failure rather than near it.
The caveat is that programme design is individual, and anyone with joint, cardiac or metabolic constraints needs a professional rather than a forum.
Ten sets per muscle group per week, twice weekly, loads held. That is most of it.
edited 6 Feb 2026 by kirsi_lahtinen — clarified the distinction between purity and content
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