Issue #4: Progressive Overload

✍️ Author’s Note

Welcome to this edition of the Threshold Lab newsletter! I’m Stephen Pelkofer, an experienced HYROX athlete with a men’s pro personal best of 59:41 and men’s pro doubles best of 51:39. If you want to learn about my story and how I got here, check out this Instagram post here.

The goal of this newsletter each week is to pick a training topic related to running or HYROX, do deep research into it, and provide actionable protocols that the reader can take away and apply to their training immediately. Let me read the research, listen to the experts on podcasts and youtube, and then give you the tools to make it work for you.

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I have helped many athletes either achieve a new PR or prepare for their first race. Fill out the 1:1 intake form below if you want a free consult – you can also learn more about my coaching experience here: tresholdlab.co

👨‍💻 Introduction

Topic: Progressive Overload

Progressive overload is the practice of gradually increasing training stress. Whether you’re a dedicated runner chasing a new PR, or a HYROX competitor tackling strength and endurance in tandem, you can’t escape this fundamental principle. Push a bit more, go a little faster, or lift slightly heavier, and your body adapts. But if you never up the challenge, improvements plateau.

⚡️ Fast Finds for the busy reader

• Stuck in a plateau? You’re probably not progressing your training in any way, or you’re pushing too hard all the time.

• Track everything: you have to know what you have done in the past to understand if you’re improving.

• Overload smart: lift heavier, run faster, or go longer, but don’t do it all at once.

🔬 Deep Dive

Some athletes train consistently for weeks and months but see little improvement. Lack of progress often comes down to insufficient (or non-existent) progressive overload. This is my biggest gripe with group fitness gyms that program the same workouts for their clients week after week. While some activity is better than no activity, progressions of intensity, volume, or duration are needed to improve.

One study I reviewed this week compared two 6-week endurance programs. One where the individuals ran the same intensity and duration for 18 sessions (control group), and one where individuals slightly increased the intensity (using treadmill pace) each week (progressive overload group). The analysis demonstrated that VO₂ max significantly increased more in the progressive overload group compared to the control group [1]. If you’ve been doing the same paced runs week after week and haven’t been seeing improvement, you likely need to increase the stress of your workouts in some way – this could mean running longer, running faster, or decreasing the duration of the rest period during an interval session.

So is it better to increase pace or duration? Per usual, it depends on things like your fitness goals, age, training age, and many other factors. Researchers have hypothesized that younger athletes (under 50) will get greater fitness gains by progressively increasing exercise intensity (running faster or with higher effort), since higher intensities push the heart rate and metabolic stress to new heights. In contrast, older athletes (50+) might gain just as much benefit by simply extending the duration of exercise sessions while keeping the pace constant [2]. Aging brings declines in cardiovascular and muscle-tendon recovery, so piling on intensity isn’t always feasible as you get older. What you are progressing is often dependent on what portion of a season you are in, how close you are to a goal race, and what that race is. For example, if you have a 5k race in 4 weeks, it wouldn’t be smart to make the main focus of your program to increase your long run to 20+ miles over that period.

Progressive overload is the bedrock of strength training as well. In lifting, you can progress by adding weight, doing more reps, increasing sets, or even shortening rest intervals. A recent study put two popular overload methods head-to-head: increasing load versus increasing reps. Over 10 weeks, researchers had 39 novice lifters train their legs so that one leg gradually lifted heavier weights (fewer reps per set), while the other leg performed more repetitions at a lighter weight that increased over time. The outcome? Both legs got significantly stronger and more muscular, with no meaningful difference in strength gains or muscle size between the “heavy weight” leg and the “high reps” leg [3]. In fact, each leg’s one-rep max on the leg extension improved by about 30% regardless of which progression protocol was used. The lesson for beginners is that you don’t need to obsess over the perfect scheme initially. Whether you add five pounds to the bar or squeeze out a couple more reps, as long as you steadily push your boundaries, your muscles will adapt and grow.

For those training in multiple domains, say you’re prepping for a HYROX competition or balancing heavy lifting with marathon prep, implementing progressive overload becomes a balancing act. You want improvements in both endurance and strength, but pushing both to the max at once is a recipe for burnout and injury. The smart play is to alternate focus in phases. For a few weeks, you might dial up your running volume or intensity while keeping strength training on maintenance mode; then in a later block, increase weight/reps in the gym while scaling back running slightly. This way, you’re always overloading something without overloading everything simultaneously.

The bottom line: progressive overload should always be top of mind in your program, but what you overload (distance vs. speed, load vs. reps) may shift over time. By applying the right kind of overload at the right time, you’ll continue to grow faster, stronger, and fitter without hitting those dreaded plateaus.

Time for the lab notes ⬇️

🧪 Lab Notes

In every issue of this newsletter, the “Lab Notes” are going to be the protocols that you can apply to your training and routine right away. The goal of this section is to translate the science into actionable steps for the reader, whether you’re a recreational runner/HYROX competitor, or someone pushing the limits of their peak potential.

• At the beginning, don’t sweat the details: New to strength training? Just focus on doing a bit more each session. Whether that means more weight on the bar or more reps, both approaches build strength and muscle in novice lifters. Consistency and small increases each week will take you far.
  

• Track what you’re doing: It is very hard to remember what weights you did week-to-week for every single exercise, or what paces you ran each threshold interval at 3 weeks ago. One of the biggest benefits my 1:1 clients acknowledge is how much it helps them out when they can go back 2, 4, or 6 weeks ago and see exactly what they did. Tracking is everything.
  

• One overload at a time: When training for concurrent goals (like in HYROX), avoid maxing out everything all at once. Emphasize one area while maintaining others, then rotate. For example, ramp up run mileage or speed in one phase, then shift to increasing weights in another. This focused approach prevents burnout and keeps you progressing across the board. More advanced athletes can and should progress more than one thing at a time, but this takes really sound programming and knowledge.
  

• Generate small wins for lasting gains: Remember that “progressive” is the key word. Small, steady increases beat sudden, drastic jumps. Whether it’s 5 more pounds on a lift or 5 more minutes on a run, incremental overload gives your body time to adapt and lowers injury risk. Patience and persistence lead to lasting performance gains.

That’s it for this edition of the Threshold Lab. If you enjoyed this and found it useful, please share it with a friend!

What I Read and Researched for this Issue

• [1] The impact of progressive overload on the proportion and frequency of positive cardio-respiratory fitness responders

• [2] Progressive overload in cardiorespiratory exercise training for young and old: Is increasing duration or intensity of exercise more important?

• [3] Effects of Resistance Training Overload Progression Protocols on Strength and Muscle Mass