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:
Push, pull, squat, hinge, lunge, carry, rotation
Main muscle groups activated during the exercise
Direction of resistance: horizontal, vertical, axial
Compound vs isolation, body position
Supporting muscle groups involved
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.
- 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.
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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Try the Exercise Substitution Finder →Algorithm last updated: January 2026 | Data verified quarterly
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