How to Know If Your Endurance Is Actually Improving

Fitness progress is often hard to recognize and frustrating to “track”. In this episode, CTS Coach Cliff Pittman breaks down the most reliable ways to measure endurance improvement and how those benchmarks change depending on your level of structure and available tools.

We cover easy run heart rate trends, Strava segments, interval repeatability, threshold testing, and why patterns over time matter far more than isolated data points.

HOST

Cliff Pittman is the Coaching Development Director at CTS, leading the Ultrarunning and Cycling Coaching staff with a specialty in guiding athletes from first-time ultrarunners to elite competitors at races like Western States 100, Leadville 100, and the Triple Crown of 200s. A competitive trail and ultra athlete himself, Cliff brings firsthand experience and a rare ability to turn complex training science into simple, actionable coaching.

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Transcript

Why Progress Feels Hard To See

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Most self-coached athletes are unsure of what to look for when it comes to measuring fitness progress. They're logging miles, showing up, putting in the work, but when you ask them whether they're actually getting fitter, they're not quite sure. The good news is the signals are already there. You just need to know where to look. And so today we're talking about three tiers of fitness benchmarks, organized by how much structure your training has and what tools you have access to. You start where you are, use what you have, and you build from there. I'm Cliff Pittman, Pro Ultrarunning Coach and Director of Coaching at CTS. I coach athletes from first-time ultrarunners to professional and world-class competitors. Now, before we get into the tiers, one framing point worth making. Progress in endurance training is slow, and meaningful adaptation happens over weeks and months, not days. A single data point tells you almost nothing, but a pattern tells you everything. So whatever benchmarks you use, give them enough time to show a trend. That's the only way they become useful. Okay,

Tier One Heart Rate Trends

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tier one. Anyone can do this. These two benchmarks require nothing more than a heart rate monitor and a running app. No structured training plan required, no coach required. If you're running consistently, you already have access to both of these. The first is easy, run heart rate trends over time. This is one of the most honest fitness signals available, and most athletes walk right past it. So here's the physiology behind it. As cardiovascular fitness improves, stroke volume increases. Your heart gets stronger and pumps more blood per beat. So it doesn't need to beat as often to deliver the same oxygen to working muscles. When that looks like in practice, it's very straightforward. You run the same route, at the same effort, in similar conditions, and log your average heart rate. If your heart rate is lower than it was three or six months ago at roughly the same pace, you're theoretically fitter. It likely won't move week to week. And if it does, there's other factors that are usually at play. But over a training cycle, a consistently lower heart rate at the same pace and effort is a legitimate and meaningful fitness signal. That's cardiac efficiency improving in

Strava Segments Without Chasing

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real time. The second tier one benchmark is Stravus segments. Now, this is the most accessible field test for the self-coached athlete, and one that most people are already sitting on without realizing it. A Strav segment is essentially a repeatable course. Same distance, same terrain, same start and finish every time. And if you run it faster under comparable conditions over the course of your training cycle, you're likely getting fitter. There's a psychological trap worth naming directly though. Benchmarking and chasing are two different things. So use segments intentionally on days designed for harder effort at a point in your cycle where the comparison is valid. Don't turn a recovery run into a segment effort just because the opportunity is there. That's measuring fitness at the cost of building it. Okay,

Tier Two Repeatable Interval Benchmarks

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tier two. Structured training is required for this one. Now, if you're following a structured training plan with designated quality sessions, you have access to more precise benchmark interval performance over time. The concept is simple. Repeat the same workout at the same point in different training blocks and compare the output. So here's a practical example. Alright, let's say the workout is a 4 by 10 minutes at lactate threshold effort. The first time you do it, you average an NGP, which is normalized graded pace, very similar to Strava's gap, of 7 minutes per mile. Now the second time you do the workout in the second block, after a delo and you're fresh, you average 650 per mile. Same workout, better output. Your threshold has likely improved. NGP accounts for elevation in terrain, making it a far more reliable comparison tool for trail runners than just raw pace alone. A few variables worth controlling here. The same workout structure, similar conditions, and a similar fatigue state going in. Don't compare a workout done fresh to one that is deep into a training block when fatigue is really high. That's not a fitness comparison, it's a fatigue comparison. For more context on threshold work and how to structure it, the training zones video covers that in full.

Tier Three Lactate Threshold Testing

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Okay, tier three, formal testing. This is the most precise benchmark on the list and the most formal. LT2, the second lactate threshold, is one of the primary determinants of endurance performance. And tracking how it changes over time is a direct indicator of meaningful fitness progression. And there are two ways you can measure it. The field test is a maximal 30-minute effort on a flat controlled surface. Your average heart rate over the final 20 minutes gives you a reliable estimate of your lactate threshold heart rate, and your average pace over the full effort approximates threshold pace. If you run the same test at similar points across different training cycles and compare the output, if approximate threshold pace improves, fitness has also improved. Now the lab test is the gold standard, it's a blood lactate assessment, it's more precise, requires access and resources, but it gives you the clearest picture of exactly where your thresholds sit. For serious athletes, periodic lab testing across a training cycle can be worth the investment. For most self-coached athletes, the field test is sufficient and repeatable. I cover the full protocol in the training zones video I referenced earlier.

Compare Yourself To Yourself

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Here's the simple message. Progress in endurance training isn't a feeling. It's a pattern of outputs measured consistently over time. You don't need all three tiers, start with tier one, easy run heart rate trends, and Strava segments gives you more information than most athletes ever act on. Now, if you're following a structured plan, add tier two and start tracking interval performance across training blocks. And if you want the most precise picture of your fitness, tier three gives you that. Through a field test, you can run yourself a lab assessment with sports performance facility. Whatever tier you're at, track consistently, give it time to show a trend, and compare yourself to yourself. Not your training partners, not to someone else's numbers, not to where you think you should be. The only comparison that matters is whether you're measurably better than you were. That's the whole thing. If you want to understand aerobic decoupling and how that works as long-term durability benchmark, the fourth variable durability video goes deep on exactly that. You can watch that one next. And if you want coaching that tracks your fitness with all three tiers as part of a deliberate training plan, visit trainride.com to connect with a CTS coach and subscribe for more coach driven ultra running education.