Split Index
Health & Fitness
Free · In‑App Purchases · Designed for iPad. Not verified for macOS.
One score for how well your lifting and running actually fit together — and an Interference Engine that shows you where they are fighting.
Split Index measures how well your training balances strength and
endurance — and what that balance is costing you.
Most fitness apps track one sport. Split Index is built for hybrid
athletes: people who lift and run, who race and squat, and who want
both without one wrecking the other.
TRACKING
• GPS route tracking for runs and rides, with offline support
• Apple Health heart rate and workout sessions
• Bluetooth heart rate straps and Concept2 PM5 rowers
• Manual entry and CSV import
WHAT YOU GET
• Split Index — one score for how balanced your training actually is
• Interference & Synergy Engine — see where lifting and cardio fight
each other, and where they help
• Per-workout cardio index for every session
• Full logging: GPS, manual entry and CSV import
PREMIUM
• Hybrid Plan — one periodised block built toward your event date,
across lifting and endurance together
• Run, ride and walk analysis — splits, best efforts, HR zones, elevation
• Injury Risk Index — know when to back off, before it becomes an injury
• Strength Index with DOTS and IPF GL tiers
• Cardio HR accountability — TRIMP, efficiency factor, decoupling
• GPT AI Coach, 90-day trends, 8-week projections, global leaderboards,
race predictions and data export
Premium is available as a monthly or annual auto-renewing subscription,
or a one-time lifetime unlock. Payment is charged to your Apple Account
at confirmation of purchase. Subscriptions renew automatically unless
auto-renew is turned off at least 24 hours before the end of the current
period. Manage or cancel in your Apple Account settings.
Privacy Policy: https://www.splitindex.co.uk/privacy
Terms of Use: https://www.splitindex.co.uk/terms
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
This new version updates and fixes a few small UI bugs. It also amends the scoring system of the engine to score more favourably towards lower heart rate activities, and any activities not logged with a heart rate will be scored based off how they are logged e.g. whether they have been logged as easy, threshold, intervals, race, etc.
I have also introduced a new score on the engine which scores relative to the athlete's median performance (50.0) and an improvement in performance would see this score at higher than 50.0 and vice versa.
The developer, Stephen Russell, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Linked to You
The following data may be collected and linked to your identity:
- Health & Fitness
- Purchases
- Financial Info
- Location
- Contact Info
- User Content
- Identifiers
- Sensitive Info
- Diagnostics
- Other Data
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Stephen Russell
- Size
- 17.4 MB
- Category
- Health & Fitness
- Compatibility
Requires iOS 15.0 or later.
- iPhone
Requires iOS 15.0 or later. - iPad
Requires iPadOS 15.0 or later. - iPod touch
Requires iOS 15.0 or later. - Mac
Requires macOS 12.0 or later and a Mac with Apple M1 chip or later.
- iPhone
- Location
- This app may use your location even when it isn’t open, which can decrease device battery life.
- Languages
- English
- Age Rating
13+
- 13+
- Contains
Messaging and Chat
User-Generated Content
Health or Wellness Topics
Social Media
- In-App Purchases
Yes
- Lifetime Subscription $79.99
- Annual Subscription $29.99
- Premium Monthly Payment $4.99
- Copyright
- © 2026 Stephen Russell