Mixed
Different methods of measuring muscle hypertrophy (e.g., ultrasound, DXA, MRI, biopsy) often yield poorly correlated results, making it difficult to determine if true hypertrophy has occurred using a single metric.
Do not rely on a single measurement tool to judge your progress. Ultrasound, DXA, and MRI measure different things (thickness, lean mass, volume) and may not correlate with each other or with actual strength gains. If you are tracking progress, use multiple metrics (strength, visual, maybe one imaging modality) and understand that 'size' is a complex, multi-component adaptation.
pre-to-post training change scores in macroscopic, microscopic, and molecular variables supporting this model are often poorly associated with one another.
Why this rating
The paper reviews numerous studies showing lack of correlation between methods.
Source
A Critical Evaluation of the Biological Construct Skeletal Muscle Hypertrophy: Size Matters but So Does the Measurement
Cody T. Haun et al. · Frontiers in Physiology · 2019
This is one finding among thousands. Every one is graded and traced to its source, so you can see what the evidence actually supports. Browse the research →