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Browse through our thousands of Lessons to gain a deeper understanding of swimming. Use our search bar located above or, if you're new to the site, use the Guided View to help narrow down the Lessons presented to you. If you use the Guided View, you’ll also be able to add your Expertise Level as an additional filter.

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Setting the 15-Meter Mark

The 15-meter underwater rule explained — and why your breakout distance data might be telling you more than you think. In this video, Glenn Mills digs into one of the most critical and often misunderstood data points in the Go Swim app: breakout distance and the 15-meter underwater rule. Using real race footage from elite-level backstroke swimmers, Glenn walks through exactly what the data means and how to interpret it correctly. A few key things every swimmer and coach needs to know: the 15-meter rule requires any part of the swimmer's head — including the chin — to break the surface before the 15-meter mark. It's not the tip of the head, it's any part of the head. That distinction matters, and it came straight from a meeting with a lead official from USA Swimming. There's also a critical detail about yards vs. meters that trips up a lot of coaches. The 15-meter markers in the app are always set in meters — even if you're swimming in a yards pool. So if your data shows a breakout distance of 15.5, don't panic. In a yards pool, that's still legal. Know your units. Most importantly — watch the elite swimmers in this video. Every single one of them is still fully underwater at the point where many age groupers have already started stroking. That's the standard. That's what's possible. Where are you right now, and how much runway do you have to improve? 🏊 New to the Go Swim app? Check out our full Import & Add Data tutorial to get started. 🏊 Subscribe for more Go Swim app tutorials, swimming tips, and coaching insights. GoSwim SwimCoach SwimmingApp UnderwaterDolphin BreakoutDistance 15MeterRule RaceAnalysis SwimData SwimmingTips SwimFast

What does DPC Look Like?

What does Distance Per Cycle actually look like in real race data — and what does it mean for your swimmer's development? In this video, Glenn Mills dives deeper into one of the most important metrics in the Go Swim app: Distance Per Cycle. Using a real 100 backstroke race as a live example, Glenn breaks down exactly what a stroke cycle looks like on video, how the app measures it, and what that number tells you about how efficiently a swimmer is moving through the water. In this particular race, the swimmer is covering 2.61 yards per stroke cycle — a remarkable number for an elite-level backstroker on track to score at Division I NCAAs. But the most important takeaway isn't the number itself — it's what you do with it. Don't compare your swimmer to elite athletes. Compare them to themselves. Every swimmer is a different size, at a different point in their physical development, and bringing different strengths to the water. The goal isn't to match someone else's DPC — it's to understand where your swimmer is today and track their progress over time. For a still-growing athlete, this year's numbers could look very different from next year's as strength and leverage naturally improve. Know where you are. Know where you want to go. That's what Distance Per Cycle data is all about. 🏊 New to the Go Swim app? Check out our full Import & Add Data tutorial to get started. 🏊 Subscribe for more Go Swim app tutorials, swimming tips, and coaching insights. GoSwim DistancePerCycle SwimCoach SwimmingApp RaceAnalysis SwimData BackstrokeSwimming SwimmingTips LongTermAthleteDevelopment SwimFast

Adding Freestyle & Backstroke Data

Freestyle and backstroke data collection works a little differently in the Go Swim app — here's exactly what to do. In this tutorial, Glenn Mills walks through how to add race data for freestyle and backstroke events in the Go Swim app, and explains the key difference from breaststroke and butterfly: stroke cycle tracking. For breaststroke and butterfly, both arms move together, so every stroke counts as one cycle. For freestyle and backstroke, you track one hand at a time — whichever hand hits first off the start or turn is the one you follow for that length. It may switch from lap to lap, but the rule stays the same: tag the first hand, and track it consistently throughout. Using a 100 backstroke as a live example, Glenn demonstrates the full Pro Data workflow — finding the strobe for an accurate start, tracking strokes and turns in real time, finalizing the data, then refining the 15-meter marks and underwater velocity breakout points for each lap. Once you understand the one-hand-per-cycle rule, freestyle and backstroke data collection is just as fast and straightforward as any other stroke. 🏊 New to the Go Swim app? Check out our full Import & Add Data tutorial to get started. 🏊 Subscribe for more Go Swim app tutorials, swimming tips, and coaching insights. GoSwim SwimCoach SwimmingApp RaceAnalysis BackstrokeSwimming FreestyleSwimming SwimData SwimmingTips SwimFast AgeGroupSwimming

Simply Adding Data

How fast can you actually collect full Pro Data from a race video? Watch it happen in real time. Skip the lengthy explanation — this video shows just how quick and efficient the Go Swim app data entry process really is. Using the same 100 breaststroke race from the previous tutorial, Glenn Mills runs through the entire workflow on iPad in Pro Data mode: tracking strokes and turns live, finalizing the data, setting the 15-meter marks for each lap, and dialing in underwater velocity — all in just a couple of minutes. Once you've done it a few times, it becomes second nature. Whether you're watching a race live at the meet or reviewing imported footage at home, the process is the same — and it's fast. A complete Pro Data set including 15-meter splits, underwater velocity, tempo, distance per cycle, and lap times, all ready to go before you've had time to put your phone away. This is the follow-up to our full Import & Add Data tutorial. If you haven't seen that one yet, check it out first for the step-by-step breakdown. 🏊 Subscribe for more Go Swim app tutorials, swimming tips, and coaching insights. GoSwim SwimCoach SwimmingApp RaceAnalysis SwimData ProData SwimmingTips SwimFast AgeGroupSwimming SwimTech

Importing Video & Adding Data

Learn how to import any race video into the Go Swim app and collect accurate stroke data in just a few minutes — step by step. In this tutorial, Glenn Mills walks you through the complete process of importing a video into the Go Swim app on iPad and adding race data from start to finish. Whether it's a race you filmed at a meet or an older underwater video saved in your photo library, getting it into the app is straightforward — and the data it produces is incredibly powerful. In this video you'll learn how to import a video from your photo library into the Go Swim app, how to set the aspect ratio for a full-screen view, how to sync the race start using the strobe or best available frame, how to track strokes, turns, and the finish in real time as the race plays, and how to finalize your data and switch between Basic and Pro data modes. In Basic Data mode, the app instantly calculates breakout distance, breakout split, stroke cycles, tempo, distance per cycle, swim velocity, turn time, and lap time. Switching to Pro Data mode adds precise 15-meter splits and more accurate underwater velocity, calculated by scrubbing to the exact frame where the swimmer's head breaks the surface. Once your data is ready, tap the score button in the bottom left corner and the app connects back to Go Swim to recommend specific videos your athlete can watch to address exactly what the data revealed — turning numbers into a clear action plan for improvement. 🏊 Subscribe for more Go Swim app tutorials, swimming tips, and coaching insights. GoSwim SwimCoach SwimmingApp RaceAnalysis SwimData SwimmingTips AgeGroupSwimming SwimFast TempoTrainer SwimTech

Using the PRO Data Mode

Pro Data mode takes your race analysis one step further by pinpointing the 15-meter breakout with frame-by-frame precision. After collecting your basic data, switch to Pro Data and scrub through the video on each length, holding the 15-meter mark and scrolling until the swimmer's head reaches exactly that point. Do this for both lengths, save each data point, and the app will calculate more accurate underwater velocity and a true 15-meter split — giving you a deeper, more complete picture of how the athlete is performing off every wall.

Using the BASIC Data Mode

Using the Go Swim app in Basic Data mode makes collecting race data fast and straightforward. Start by syncing to the strobe for an accurate race start, then simply tap for each stroke, each turn, and the finish as the race unfolds. If you miss the finish tap in real time, no problem — just scroll to the official time from the scoreboard, hit finish, and finalize. In just a minute or two you'll have breakout distance, stroke counts, turn data, and everything else you need. Basic Data mode captures 95% of what most coaches are looking for, quickly and easily — and Pro Data mode takes it even further, which we'll cover in a future video.

Filming the Board

After filming a race, always take a moment to film the scoreboard before the times clear. The times recorded during the race are essentially hand-timed estimates, so having a shot of the official board gives you the exact finish time to reference later. When you go back to enter the data, you can adjust your recorded time to match what was on the board, ensuring your final data set is as accurate as possible.

Filling in Data Gaps

Filming at a busy swim meet means dealing with plenty of visual interference — people walking through the shot, backstroke flags, splashing, and other swimmers in the frame. When your view of a swimmer gets blocked, the key is understanding their rhythm. Once you've locked into the pattern of their stroke, you can confidently fill in the gaps even when you can't see every arm entry clearly. Don't stress about missing one or two strokes — a slight imperfection here and there still produces a solid, reliable overall data set.

Setting the Start

Getting an accurate race start in Go Swim is easier than you think. When filming, try to capture the starter's strobe in frame — even from a distance you can zoom in to see exactly when it fires. Since light travels faster than sound, syncing your start to the strobe flash gives you a precise timestamp down to the hundredth of a second. Simply adjust the aspect ratio for a full view, spot the strobe, and tap the start button at the exact moment it lights up. That's all it takes for a perfect, accurate start.

Welcome to App Shorts

Welcome to Go Swim Shorts with Glenn Mills! In this series, we'll show you how to use your mobile device to film your swimmer's races and collect meaningful data that drives real improvement. By understanding where your swimmer is today — and where they can go — you'll have a clear roadmap to help them become a better, faster, more efficient swimmer. We're here to help every step of the way.