Comparison

viiiv vs iFour Core

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

viiiv

This app facilitates isometric strength training by connecting to specialized hardware. It allows users to select from various exercises, track real-time force data, and view progress reports with trend graphs. Users can log their sessions, create group accounts for clients, and share detailed performance summaries.

Highlights
  • 8+ isometric exercises
  • Real-time force data graphing
  • User account for data logging
  • Group accounts for clients
  • Progress reports with trend lines
  • Sharable 2-page session reports
Features
Read full description

Choose from 8+ exercises and graph real-time force data while performing isometric strength training exercises on the ViiV-Rx. This app will not function without the viiiv Pro machine to connect to - see https://viiivfitness.com Log into your User account to save and track your exercise data or use in Guest Mode without an account. Or create a Group Account for your wellness business to track all of your clients. Select either 5 (default) or 10 seconds per exercise. A 50% of Previous Best threshold Trigger Start insures maximum effort. Progress Reports with trend line graphs for each user and exercise. A 2-Page Report sharable via email, message, etc. shows Total Overall Strength Improvement after each viiiv session.

About

iFour Core

This app offers a personalized core workout program designed by physical therapists. It adapts to your individual anatomy and fitness level, providing daily workouts under 10 minutes with video demonstrations. Access nutrition guides and trainer support as a member.

Highlights
  • Personalized core workout program
  • Physical therapy approved exercises
  • Daily workouts under 10 minutes
  • Video demonstrations of exercises
  • Nutrition guides and support
  • Fitness test for customized plans
Features
Read full description

Every individual’s anatomy is different which is why we have designed a customizable, physical therapy approved core program. The iFour Core app addresses specific areas of your core to help you develop the strongest core imaginable without injury. Each workout is under 10 minutes, is suitable for all fitness levels, and can take place in the home or at the gym. As a member of the iFour Core app, you will receive new workouts every day, nutrition guides, and support. FREE 7-day trial for new members! HOW IT WORKS: After completing the iFour Core fitness test, you will get a core strength rating. This rating is broken up based on muscle fibers worked (intrinsic, rectus, obliques & transverse). The iFour Core app customizes the exercises each day based on your fitness test performance and current level of core strength. WHAT MAKES US DIFFERENT: Life is full of surprises, plateaus, and challenges. We created this app with this in mind allowing you to recalibrate your individualized workout formula at any point you feel necessary. Unlike other programs, this is not simply just hitting “reset,” and repeating the same exercises from previous days. This is a full recalculated algorithm taking you from your new “starting point” with a proven plan of attack to help you once again improve. iFour Core Features: Workout & Fitness Planning • Functional yet challenging core rotations, ranging from 5-10 Minutes! • Includes regressions to decrease difficulty and progressions to advance the exercises as you improve. • 323 unique core exercises. • 137 additional core exercises with 6 different pieces of equipment to choose from. • Video demonstrations of all 323 core exercises. • Designed for all levels, whether you are coming out of physical therapy or an elite athlete! • Take the fitness test and as you get stronger, unlock more core exercises prescribed for you. Tracking & Fitness Motivation • Workout along with J, a seasoned trainer for celebrities, professional athletes, and others. • Track your daily progress in both your Fitness Test and Workout History. • Share your results on your favorite social media platform. • Keep up to date and learn with the latest iFour videos. Subscription Pricing & Terms iFourCore is free to download. Ongoing use requires an active subscription, available on a monthly or annual basis. New customers are eligible for a 7-day free trial. Annual subscriptions are billed the total fee from the purchase date. Monthly subscriptions are billed per month. Payment will be charged to your credit card through your iTunes account at confirmation of purchase. Subscription renews automatically unless cancelled at least 24 hours prior to the end of the subscription period. There is no increase in price when renewing. Subscriptions can be managed and auto-renewal turned off in Account Settings in iTunes after purchase. Once purchased, refunds will not be provided for any unused portion of the term. Read our full Terms and Conditions & Privacy Policy: https://www.ifourlife.com/

Screenshots

viiiv4 screens
iFour Core4 screens

Verdict

The call

The clearest difference is in-app purchases: viiiv at none against iFour Core's 2. iFour Core's advantage is ratings volume (28 vs 2). On price, rating, update cadence and ads there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. iFour Core sells 2 in-app purchases, starting at $5.99 per month. viiiv asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

On the App Store both sit at effectively the same score — 5.0 for viiiv against 5.0 for iFour Core. That said, the two scores are not equally well evidenced: iFour Core has 28 ratings behind it against 2, so its average is the more settled of the two.

UpkeepUpdate frequency

Both ship on a similar rhythm, roughly every 2 months. The most recent releases landed on September 8, 2026 and June 4, 2026 respectively.

Scorecard3 real differences · 7 level
viiiv versus iFour Core: the parameters behind the verdict, then further details
ParameterviiiviFour Core
PriceFreeFree
Rating5.0 (2 ratings)5.0 (28 ratings)
Positive reviews—100.0% of reviews
Number of ratings228 — better
Update frequencyEvery 2 monthsEvery 2 months
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFree — betterFree with in-app purchases
DevicesiPhone, iPad, iPod — betteriPhone, iPod
Requires iOS12.011.0 — better
Further details — not scored
Size36 MB39 MB
Age rating4+4+
DeveloperLess Is More LLCifour.life, LLC

Customer experience

viiiv

All ratings2 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

iFour Core

All ratings28 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews11 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

viiiv

No in-app purchases

2 purchases

iFour Core

Subscriptions2
  • Monthly7 Days trial$5.991 Month
  • Annually7 Days trial$29.991 Year

Questions

Is viiiv free?
viiiv is free to download, with no in-app purchases.
Is iFour Core free?
iFour Core is free to download, with in-app purchases available.
Which has better reviews, viiiv or iFour Core?
viiiv and iFour Core are both rated 5.0 out of 5 on the App Store, from 2 and 28 ratings respectively.
Do viiiv or iFour Core have ads?
Neither viiiv nor iFour Core shows ads.
Which is updated more often, viiiv or iFour Core?
viiiv ships an update every 2 months, and iFour Core every 2 months. Most recently, viiiv was updated on September 8, 2026 and iFour Core on June 4, 2026.

Other comparisons