TestFlight beta · By application · US

Apply for the TeraThreshold beta

The beta is for sub-elite and elite marathoners, and entry is by application. Show us a fast marathon on a certified course and the mileage behind it, with links we can check, and we review your application by hand. If you are accepted, Apple emails you an invite to TestFlight, its app for trying iPhone apps before they reach the App Store. Sign in with Garmin, and every run is scored for running form and injury risk against your own baseline.

What we look for

  • A fast marathon3:10:39 or faster (chip time) on a certified course in the last three years. That is a Race Fitness of 50, where TeraThreshold's Sub-elite level starts.
  • High mileage50 miles (80 km) a week or more, averaged over the last 12 weeks.
  • Proof we can openA link to your result on the race's official results page, and a link to your training log on Garmin Connect or Strava.
  • iPhone and Garmin, in the USAn iPhone with iOS 17 or later and a Garmin watch that syncs to Garmin Connect. The beta is open to runners who live in the United States; your marathon can be anywhere.

Your application

Four short sections. Every field is required unless it says optional. Have two links ready: your official result and your training log.

01 You

As it appears in the race results.

If you are accepted, Apple sends the TestFlight invite here.

02 Your marathon

Your fastest marathon on a certified course in the last three years.

Races are listed to identify your result. TeraThreshold is not affiliated with any race.

Only if you chose Other certified marathon. The course must be certified by USATF, by World Athletics or AIMS, or by the national athletics federation where the race was held. Most city marathons are, and the race website usually says so. Virtual, indoor, treadmill and trail marathons do not count.

Chip time, h:mm:ss.

Type your finish time to see its Race Fitness. The beta's line is 50, a 3:10:39 marathon.

The page on the race's or the timing company's site that shows your name, the date and your time.

03 Your training
Unit

The beta asks for 50 miles (80 km) a week or more, as your training log shows it.

Your Garmin Connect or Strava profile. While we review, make the last 12 weeks of runs, and your marathon if you can, visible to everyone.

Other results, your club or coach, or context for your training block.

04 Setup and confirmation

We read every application by hand. If yours is accepted, we give Apple your email address so TestFlight can send the invite.

Accepted runners are added to the TestFlight group, and Apple emails their invites once the current beta build clears its TestFlight review.

How to join

We review every application by hand. If you are accepted, the rest takes about five minutes on your iPhone.

  1. Apply

    Send the application above with your official result and your training log. We review every application by hand.

  2. Install TestFlight

    Get TestFlight, Apple's free app for beta testing, from the App Store on your iPhone.

  3. Accept the invite

    Apple emails your invite. Open it on your iPhone, tap View in TestFlight, then install TeraThreshold.

  4. Sign in with Garmin

    Open TeraThreshold and tap Continue with Garmin. Your runs arrive after your watch syncs.

Applying and the beta

Who can apply?

Sub-elite and elite marathoners who live in the United States. You need a marathon in 3:10:39 or faster (chip time) on a certified course in the last three years, and 50 miles (80 km) a week or more averaged over the last 12 weeks, with links that prove both. That marathon time is a Race Fitness of 50, where TeraThreshold's Sub-elite level starts; Elite starts at 60. You also need an iPhone with iOS 17 or later and a Garmin watch that syncs to Garmin Connect.

Does my marathon have to be a Major?

No. A World Marathon Major such as Boston, Chicago, New York City or Tokyo counts, and so does any other marathon on a certified course, such as Paris or your local city marathon. Certified means measured and certified by USATF, by World Athletics or AIMS, or by the national athletics federation where the race was held; most big city marathons are, and the race website usually says so. Virtual, indoor, treadmill and trail marathons do not count. TeraThreshold is not affiliated with any race.

Is the line the same for everyone?

Yes. It is 3:10:39 for every age and sex: the marathon time for a Race Fitness of 50, computed from your chip time with the formula the app uses for its race predictions. Race Fitness 50 is where the app's Sub-elite level starts.

What if I run in kilometers?

Then the line is 80 km a week, averaged over the same 12 weeks; the form takes either unit. In the app, distances and paces show in miles by default, and you can switch to kilometers in Settings.

How do you check my application?

By hand. We open your results link and look for your name, the race, the date and your chip time, then open your training log and add up your running over the 12 weeks before you applied. Having the marathon itself in your log helps, because it ties the result to you. We only need dates, distances and times, so you can hide anything else, but we have to be able to open both links. There is no set review time.

What happens to my application data?

Only the TeraThreshold team sees it. If you are accepted, we give Apple your email address so TestFlight can invite you, and nothing else from your application. If you are not accepted, we delete your application within 90 days of the decision, and an application below the standard is never stored. To withdraw it or have it deleted sooner, email support@terathreshold.com. Read the details in our Privacy Policy.

I applied but no invite has arrived.

Applications are reviewed by hand and there is no set review time. If you are accepted, the invite comes from TestFlight, so check your spam folder; if the current beta build is still in Apple's review, invites go out when it is approved. To ask about your application, email support@terathreshold.com from the address you applied with.

Does the beta cost anything?

No. Applying is free, every new account starts with 30 days of Pro, and purchases made in a TestFlight build are never charged.

How do I send feedback?

Take a screenshot in the app and tap Share Beta Feedback, or open TestFlight and tap Send Beta Feedback. You can also email support@terathreshold.com.

How long does a beta build last?

Each TestFlight build works for 90 days. With automatic updates on, TestFlight installs new builds for you as they arrive.

Can I leave the beta?

Yes. Tap Stop Testing in TestFlight, or delete the app. To delete your data as well, delete your account in the app's Settings first; everything is removed after a 30-day window.

What does TeraThreshold do?

It scores every Garmin run for running form and injury risk against your own baseline, and keeps your Race Fitness, paces and heart-rate zones current. Watch the 35-second tour.