How does the exercise similarity algorithm work?

Our algorithm uses weighted Jaccard similarity across 6 factors: movement pattern (35%), primary muscles (25%), force vector (15%), exercise mechanics (10%), secondary muscles (10%), and difficulty level (5%). The final score represents how similar two exercises are for training purposes.

What does a 90% similarity score mean?

A 90%+ similarity score indicates an excellent match - the substitute exercise provides nearly identical training stimulus to the original, targeting the same muscles with similar movement mechanics.

Why is movement pattern weighted highest at 35%?

Movement pattern is the most critical factor because it determines the fundamental motor pattern being trained. Exercises with matching movement patterns develop similar coordination, strength curves, and motor skills.

How We Calculate Exercise Similarity

Our algorithm analyzes 1,600+ exercises using weighted biomechanical factors to find the best substitutes for your available equipment.

The Weighted Similarity Algorithm

We use a weighted Jaccard similarity approach that compares exercises across six key dimensions. Each factor is weighted based on its importance for achieving similar training outcomes:

35%

Movement Pattern

Push, pull, squat, hinge, lunge, carry, rotation

25%

Primary Muscles

Main muscle groups activated during the exercise

15%

Force Vector

Direction of resistance: horizontal, vertical, axial

10%

Exercise Mechanics

Compound vs isolation, body position

10%

Secondary Muscles

Supporting muscle groups involved

Difficulty Level

Skill and strength requirements

Why These Weights?

Movement Pattern (35%)

The movement pattern is the most critical factor because it determines the fundamental motor pattern being trained. A horizontal push (bench press) and a horizontal pull (row) work different muscles entirely, even if both use a barbell. Exercises with matching movement patterns develop similar coordination and motor skills.

Primary Muscles (25%)

The target muscle determines hypertrophy outcomes. Two exercises targeting the chest will both develop chest size, even if their movement patterns differ slightly. We use muscle group overlap calculated via Jaccard similarity.

Force Vector (15%)

The direction of resistance affects muscle fiber recruitment. A horizontal chest press hits different portions of the pectorals than an incline press. Force vectors categorized as: axial (along spine), horizontal, vertical, anteroposterior, and rotational.

How Similarity Scores Are Calculated


Similarity Score =
    (Movement Match × 0.35) +
    (Muscle Overlap × 0.25) +
    (Force Vector Match × 0.15) +
    (Mechanic Match × 0.10) +
    (Secondary Muscle Overlap × 0.10) +
    (Difficulty Proximity × 0.05)

Each factor contributes to the final score. For categorical matches (movement pattern, force vector), exercises either match (full points) or don't (zero points). For set-based comparisons (muscles), we use Jaccard similarity: the intersection divided by the union of the muscle sets.

Score Interpretation:

90%+ - Excellent match, nearly identical training stimulus
80-89% - Great match, minor differences
70-79% - Good match, some trade-offs
60-69% - Acceptable alternative
<60% - Different exercise, limited substitution value

Data Sources & Validation

Our exercise database combines data from:

Open-source fitness databases with 1,600+ exercises
Peer-reviewed biomechanics research for movement classification
EMG studies for muscle activation patterns
Expert review from certified strength coaches

We continuously refine our algorithm based on user feedback and emerging exercise science research.

Created by Certified Fitness Professionals

This algorithm was developed by FitnessVolt's team of certified strength and conditioning specialists (CSCS) and exercise physiologists. Our methodology has been validated by over 10,000 users and refined based on real-world feedback.

🎓 NSCA-CSCS Certified

📊 10,000+ Users Validated

🔬 EMG Research-Based

Data Sources

Exercise Database: 1,600+ exercises from verified fitness databases
Movement Classification: Based on functional movement screening principles
Muscle Activation: EMG studies and peer-reviewed biomechanics research
Difficulty Ratings: Calibrated by certified personal trainers

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Algorithm last updated: February 2026 | Data verified quarterly