RSP App vs Stretchr
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
RSP App
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RSP APP: High-Performance Training Application The digital extension of the Isoinertial (Eccentric) machines manufactured by einercial.com. RSP APP measures training performance in real-time via a Bluetooth streaming data connection. Performance is measured in power output (watts) and work cycles. Using these two indicators, the app provides users with valuable insights into their machine usage and performance. Users can save and review their training history. The app includes presets for each of the three machines that feature the hardware connection terminal. HOW DOES IT WORK? The system consists of a hardware component connected to the machine (compatible with any model from the manufacturer). This hardware is a rotary encoder, a high-tech device capable of registering up to 1,000 points per rotation of the yo-yo. On the other end, the app receives and processes this data. Let’s dive into the details: THE ROTARY ENCODER • Completely wireless: The RSP encoder is designed with ergonomics and usability in mind. • Long-lasting battery: It features a rechargeable battery with a standard female mini USB connector for charging with any standard mobile charger. EASY INSTALLATION ON RSP MACHINES: JUST CONNECT AND GO The encoder fits all RSP machines. It attaches using three small standard screws. DATA TRANSMISSION VIA BLUETOOTH The connection to the app is through Bluetooth, ensuring a fast and reliable link. The encoder sends data to the app, allowing you to move up to 15 meters away—ideal for trainers. BASIC WORKFLOW WITH THE APP 1. CONNECT THE APP TO A MACHINE Once the encoder is turned on and Bluetooth is enabled on your phone, the app will detect the signal and prompt you to select a machine. It will also request mass (weight) configuration. Once both are confirmed, you can start training. 2. START TRAINING: COACH MODE Another option, particularly useful for personal trainers or gym instructors, is to register multiple athletes in the same session. You can add as many as needed, recording the strength values for each individual and creating a comprehensive session history. 3. REAL-TIME PERFORMANCE MONITORING The app displays the machine and its selected mass configuration on the screen. It also shows real-time performance data, including power per cycle, time, power output, and other session details—all live on your screen. OTHER TRAINING MODES FOR HIGH-PERFORMANCE CIRCUITS Once familiar with the machine and its limitations, you can choose a training mode based on power ranges. The app leverages session history to provide data on strength ratios, best performances, and their correlation with lower scores. With this information, you can select training modes based on maximum and minimum power ranges, challenging yourself to stay within the interval. RSP Inertial Performance | Tools for Athletes
Stretchr
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You already move. Strechr makes sure your body can keep up. Built for people who run, lift, cycle, surf, or just refuse to slow down. Strechr gives you short, targeted mobility sessions focused on what your body actually needs. No generic stretches, no hour-long routines. Just the right work, done consistently, on the areas that hold you back. HOW IT WORKS Answer a few questions about your sport, your tight spots, and how much time you have. Strechr builds your protocol around your answers, whether that's your hips, knees, shoulders, or wherever you need it most.Each session runs 10 to 30 minutes. You pick the time, Strechr picks the exercises.As you progress, new movements unlock. Things that felt stiff in week one start feeling different by week four. That's the point. WHAT YOU GET Mobility sessions built around your weak zones Strength and stretch combined, not just passive holds Breathwork to open and close each session Progressive unlocks as your body adapts Morning, evening, and post-training formats WHO IT'S FOR You don't have to be a pro athlete to use Strechr. If you move regularly and want to keep moving without pain, stiffness, or injury, this is for you.Runners dealing with knee or hip tension. Cyclists who feel tight through the lower back. Lifters losing shoulder mobility from heavy pressing. Anyone who keeps putting off their stretching and finally wants a simple way to actually do it.Strechr requires a subscription, available monthly or yearly. The yearly plan includes a SUBSCRIPTION INFORMATION Strechr requires a subscription to unlock full access. Plans: monthly and yearly The yearly plan includes a 14-day free trial Payment is charged when you confirm your purchase Manage or cancel anytime in your Account Settings Subscriptions auto-renew unless cancelled at least 24 hours before the renewal date EULA: https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Screenshots
Verdict
The clearest difference is in-app purchases: RSP App at none against Stretchr's 2. RSP App also leads on iOS requirement (13.0 vs 15.1). On price, update cadence, ads and device support 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
Both are free to download. Stretchr sells 2 in-app purchases, starting at $8.99 per month. RSP App asks for nothing beyond the download.
RSP App ships an update every 2 months, Stretchr monthly. The most recent releases landed on November 7, 2026 and October 31, 2026 respectively.
| Parameter | RSP App | Stretchr |
|---|---|---|
| Price | Free | Free |
| Update frequency | Every 2 months | Monthly — better |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Devices | iPhone, iPad, iPod — better | iPhone, iPod |
| Requires iOS | 13.0 — better | 15.1 |
| Further details — not scored | ||
| Size | 23 MB | 66 MB |
| Age rating | 4+ | 12+ |
| Developer | Inercial Performance Sl. | Adrien Marchetti |
In-app purchases
RSP App
No in-app purchases
Stretchr
- Monthly subscription$8.991 Month
- Annual subscription14 Days trial$79.991 Year









