Beyond FITT
Bibliographic record
Abstract
Research on physical activity and health, including planned and structured forms such as acute and chronic physical exercise, has focused on understanding potential dose-response relationships.Traditionally, the variables of (i) Frequency, (ii) Intensity, (iii) Time, (iv) and Type (known as the FITT principle) have been used to operationalize the dose of physical activity.In this article, we describe the limitations of FITT and propose that it should be complemented by the underappreciated variable density, which defines the temporal distribution of physical activity stimuli within a single bout of physical activity or between successive bouts of physical activity relative to time spent resting (e.g., in napping/sleeping or sedentary behaviors).Using the field of physical activity and brain health as an example, we discuss challenges and opportunities for further research to use density to improve our understanding of doseresponse relationships between physical activity and health-related outcomes.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.012 | 0.055 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.003 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.004 |
| Scholarly communication | 0.006 | 0.011 |
| Open science | 0.003 | 0.005 |
| Research integrity | 0.003 | 0.005 |
| Insufficient payload (model declined to judge) | 0.036 | 0.016 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".