Methodology
How the Move Index works, what data it uses, and where the numbers come from. Full transparency into every assumption.
What Move Index Is
Move Index is a research-backed scoring system that helps desk workers understand the estimated value of short movement breaks. It produces a composite 0–100 score across four dimensions, always accompanied by confidence levels and caveats.
It is designed to compare short movement breaks within a desk-work context, not to rank all exercise universally. It is not a calorie calculator, a medical device, or a replacement for professional exercise prescriptions.
The simple version
Move Index asks four simple questions before it scores a movement:
Question 1
How much of your body does this use?
Question 2
How much energy does it cost?
Question 3
How much does it undo desk posture?
Question 4
How realistic is it during a workday?
The Four Dimensions
Muscular Demand
Total muscle mass recruited multiplied by activation intensity. Weighted by relative muscle group size (gluteals and quadriceps contribute more than forearms).
Source: Published EMG studies (%MVIC)
Metabolic Cost
Energy expenditure above resting, scaled relative to brisk walking (3.5 METs) using square-root normalization for diminishing returns at high intensities.
Source: 2024 Compendium of Physical Activities
Mobility Value
Joint range of motion and posture correction potential. This is the most modeled dimension and should be interpreted as a directional estimate rather than a direct measurement.
Source: Biomechanics literature (mostly modeled)
Desk Practicality
Can you do this at your desk? Considers space, noise, equipment, recovery time, and professional appearance. Weighted highly because Move Index is designed for real-world work breaks, not lab-optimal exercise ranking.
Source: Expert heuristic (modeled)
Data Classification
Every data point is classified by how it was obtained:
Measured
Directly from published research. Highest confidence.
Derived
Calculated from measured inputs via established formulas.
Modeled
Estimated from heuristics or analogy. Lower confidence.
28
total exercises
9
with measured EMG data
19
primarily modeled
Confidence Scores
Each score includes a confidence level (0–1) computed from data coverage, study quality, population match, and data source type. The system never suppresses low-confidence scores — it shows them with appropriate caveats.
How the Scoring Engine Was Built
The scoring algorithm was developed using an adaptation of Andrej Karpathy's autoresearch pattern. An AI agent iteratively modified the scoring logic, and each iteration was evaluated against a curated reference dataset using five metrics: score ordering, confidence calibration, consistency, interpretability, and simplicity.
Improvements were kept; regressions were reverted. The improvement history is itself part of the product — full transparency into how the algorithm evolved.
Evaluation Framework
The scoring engine is evaluated against five metrics (lower is better):
Do higher-value movements score above lower-value ones?
Do confidence bands match actual uncertainty?
Are similar exercises scored similarly?
Are explanations clear, accurate, and appropriately caveated?
Is the algorithm as simple as possible without sacrificing quality?
- Move Index scores are estimates, not clinical measurements. They should not be used for medical decisions.
- Mobility Value and Desk Practicality are primarily modeled from expert heuristics, not direct measurement.
- EMG data comes from studies with varying populations, sample sizes, and protocols. Individual results will differ.
- Metabolic cost varies significantly with body weight, fitness level, and exercise form.
- The system does not account for individual health conditions, injuries, or contraindications.
8 peer-reviewed publications underpin the Move Index scoring system. Access full text, PDFs, and formatted citations below.
2024 Adult Compendium of Physical Activities: A Third Update of the Activity Codes and MET Values
Barbara E. Ainsworth, William L. Haskell, ... et al.
Primary source for MET values across all exercises
Electromyographic activity in the gluteus medius, gluteus maximus, biceps femoris, vastus lateralis, vastus medialis and rectus femoris during the Monopodal Squat, Forward Lunge and Lateral Step-Up exercises
José M. Muyor, Isabel Martín-Fuentes, ... José A. Antequera-Vique
EMG activation data for squats, lunges, step-ups, and deadlifts
Key Factors Associated with Adherence to Physical Exercise in Patients with Chronic Diseases and Older Adults: An Umbrella Review
Daniel Collado-Mateo, Ana Myriam Lavín-Pérez, ... et al.
Rectus femoris and erector spinae activation during sit-to-stand
Sitting for Too Long, Moving Too Little: Regular Muscle Contractions Can Reduce Muscle Stiffness During Prolonged Periods of Chair-Sitting
Ewan Thomas, Guglielmo Pillitteri, ... et al.
Evidence that brief periodic contractions prevent sitting-induced stiffness
Comparison of energy metabolism and muscular activity between sitting on a stability ball and office chairs
Stability ball increases O2 consumption 13% and muscle activity 55% vs standard chair
2011 Compendium of Physical Activities
Barbara E. Ainsworth, William L. Haskell, ... et al.
Established MET reference values for common activities
Estimating energy expenditure during bodyweight resistance exercise
MET values specific to bodyweight resistance exercises at various intensities
Non-exercise activity thermogenesis in the workplace
Framework for valuing movement breaks in sedentary work contexts