An experiment in fitness: AI-coached 25-minute 5K
Using ChatGPT (GPT-4) as a text-based running coach
I recently used ChatGPT (GPT-4) to help me hit my goal of running a 25-minute 5K run and decided to write a bit about my experience.
Motivation
As someone who works at a computer all day, I sit at a desk for a shocking amount of time, so I’ve started exercising to hopefully offset my ass being in a chair for 12 hours a day (with some automated standing forced in).
Until now, I’ve been lifting weights 3 times a week and running once a week. I’ve been doing this schedule fairly consistently for 6 months—1 year. My fastest 5K time at the start of this was 27:37.
According to runninglevel.com, 27:37 puts me at a “beginner” level, and 25:00 would put me up to a “novice” level. (The world record is 12:51!?)
As for the 25-minute goal, there isn’t anything specific or special about that time. It just felt like a nice balance between progressing on my current time and not being too far out of reach. In retrospect, I really didn’t know if it was a good or bad goal. If I were to do it again, I’d probably ask ChatGPT to provide feedback on my goal or maybe even ask it to come up with some goals.
Initial thoughts
When cooking up this goal, I knew running only once a week wouldn’t cut it, and I knew I would have to run more. I also vaguely knew that you do different types of runs to help train different aspects of running. This is the point where my laziness gets in the way. I didn’t want to research other beginner running routines, dig through ad-ridden websites, and watch 30-minute Youtube videos about the best running routine for X or Y.
I’m not that passionate about running, what was interesting to me was the experiment of if an AI coach could actually help me reach my goal.
For me, the internet research route is a gamble. Either I end up being super motivated and even more focused, or I hit the great wall of decision fatigue from the hundreds or thousands of different sources and opinions found online. So, early on, I decided to use ChatGPT to create a training plan that would take any decision-making out of my hands. I would pretend it was my coach, and I would take whatever it gave me and run with it (heh).
Getting started
To get started, I looked up some basic prompt examples online and found a generic life coaching one that could be modified to fit my needs. One trick I did was adding instructions in the prompt for ChatGPT to follow up with questions to gain more information. This usually ends up feeling more like a natural conversation and provides more context for ChatGPT to hopefully give better responses.
Here is the initial prompt:
I want you to act as a personal running coach. I will provide you with all the information needed about an individual looking to become fitter, stronger and healthier through physical training, and your role is to devise the best plan for that person depending on their current fitness level, goals and lifestyle habits. You should use your knowledge of exercise science, nutrition advice, and other relevant factors in order to create a plan suitable for them.
My first request is "I have a goal of hitting a 25minute 5km run time, how would you suggest hitting it?". You should ask me questions first and gain information about my current fitness level and exercising routines to figure out the best plan for moving forward to hit my goal.
- What is your current 5km run time?
- How often are you currently running, and what is the average distance of those runs?
- Have you been doing any speed or interval training, and if so, what does that look like?
- What does your current strength training routine look like, if any?
- Do you have any history of injuries that could affect your training?
- What is your age and gender?
- Can you give me an idea of your diet and nutritional habits?
- Are there any constraints (like time or resources) that might affect your ability to follow a training plan?
- These pieces of information will allow me to craft a more personalized and effective training plan for you.
- What is your current 5km run time?
My fastest 5km run time is 27:37 - How often are you currently running, and what is the average distance of those runs?
I typically run once a week and usually run between 5k and 7k - Have you been doing any speed or interval training, and if so, what does that look like?
No I do not - What does your current strength training routine look like, if any?
I lift weights 3 times a week and do workouts for different muscle groups - Do you have any history of injuries that could affect your training?
I often get shoulder soreness and tightness that affects my weight training and after running 5k+ I do get a bit of soreness in the right side of my core - What is your age and gender?
I'm a 27 year old male - Can you give me an idea of your diet and nutritional habits?I essentially eat whatever. I typically eat a decent amount of chicken and protein, with protein shakes and protein bars. I aim for 150g of protein and 91g of fat and 304g of carbs.
- Are there any constraints (like time or resources) that might affect your ability to follow a training plan?I work 5 days a week from 9am to 5pm, I typically workout after work on weekdays and run in the morning on weekends
Within 4 messages I had the basis of the training plan. I went back and forth a few times asking it to adjust some details to better fit my schedule. Like moving the rest day to Saturday.
- Monday: Easy run (5-7K at a comfortable pace)
- Tuesday: Weight training
- Wednesday: Interval training. Start with a 10-minute warm-up run, then do 6 intervals of 1-minute fast running followed by 1-minute walk or slow jog. Finish with a 10-minute cooldown run.
- Thursday: Weight training
- Friday: Long, slow distance run (8-10K at a comfortable pace)
- Saturday: Rest
- Sunday: Weight training
- Monday: Tempo run. This means starting with a 10-minute easy run, then running 20 minutes at a challenging but sustainable pace, and finally a 10-minute cooldown.
- Tuesday: Weight training
- Wednesday: Interval training. 10-minute warm-up run, then 8 intervals of 2-minute fast running followed by 1-minute walk or slow jog. 10-minute cooldown.
- Thursday: Weight training
- Friday: Long, slow distance run (10-12K at a comfortable pace)
- Saturday: Rest
- Sunday: Weight training
- Monday: Tempo run (same as previous weeks, but aim to increase the pace during the 20 minutes)
- Tuesday: Weight training
- Wednesday: Interval training. 10-minute warm-up run, then 6 intervals of 3-minute fast running followed by 1-minute walk or slow jog. 10-minute cooldown.
- Thursday: Weight training
- Friday: Long, slow distance run (12-14K at a comfortable pace)
- Saturday: Rest
- Sunday: Weight training
That’s it. After a handful of messages, I had a fairly solid running plan. I could also jump back into the conversation at any point if I had to make adjustments, ask questions or needed clarification.
Progression
During training, ChatGPT’s proposed schedule worked pretty well for me. It felt like a natural progression without too steep of a difficulty curve. Pushing me to the edge of my current abilities without making me hate my life too much.
I also tried to keep in mind that ChatGPT is my coach. This means, any time I would have a question come to mind I would jump into the conversation and ask, like I assume you would do with a coach.
Here are some examples of questions I asked throughout:
- I’m curious, is there a reason why you chose a 6-week program?
- Could you elaborate more on what a “comfortable pace” would be?
- Can you elaborate a bit more in-depth on the interval training running that you added to the schedule?
I should mention at this point, an important thing to keep in mind with LLMs (Large language models), is that they are known to hallucinate. Which means they sometimes just totally make nonsense up. None of the messages in this experiment set off any alarms for me, but it can be especially sinister because of how confident and realistic LLMs can sound. Especially with more niche knowledge like the example below.
That's a great question! While both tempo runs and interval runs are forms of high-intensity workouts designed to improve your running performance, they focus on different physiological adaptations and are structured differently.
Tempo Runs:
A tempo run, also known as a threshold or lactate-threshold run, is a continuous, sustained effort usually performed at a "comfortably hard" pace. The pace is often described as the fastest speed you could maintain for about an hour in a race situation.
The goal of a tempo run is to increase your lactate threshold, which is the point at which lactic acid begins to accumulate in the blood more quickly than it can be removed. When you can raise your lactate threshold through training, you can run faster and longer before lactic acid build-up slows you down. A tempo run generally lasts for 20 to 40 minutes, excluding warm-up and cool-down.
Interval Runs:
Interval runs, on the other hand, involve periods of high-intensity running interspersed with recovery periods. For example, you might run fast for three minutes, then walk or jog slowly for one minute, repeating this cycle several times.
The purpose of interval training is to improve your VO2 max (the maximum amount of oxygen your body can use during intense exercise), and your running speed. The intense periods in interval training are usually performed at a pace faster than your 5K race pace, allowing your body to adapt to higher speeds.
In essence, while both tempo and interval runs are hard efforts, they differ in their structure (continuous versus broken into intervals) and their physiological targets (lactate threshold versus VO2 max and speed). Both are crucial for a well-rounded training program.
That seems to make sense 🤷
During training I set a new best 5K time which felt good and kept me pushing towards my goal. I could feel and see the improvement happening. Although, I’ll admit it wasn’t super surprising. I went from running one 5K a week to running 15-20K a week. It would have been more surprising if I didn’t see any difference.
Hitting my goal and final thoughts
At the end of the 6-week training plan, I went out for my usual weekly 5K run and completed it in 24:31! The training plan ChatGPT generated for me worked and I was a bit surprised that I beat the goal by 30 seconds. Going into the run that morning I even told my partner I didn’t think I would get it but tried anyways. It just didn’t feel like I had made that much progress in 6 weeks.
Now, you may read this and see the simplicity of the solution. “Well yeah, if you go from running 5K a week to 15-20K a week you’re going to see some improvement… you didn’t need an LLM to create a training plan for you, just run more”. I don’t think that’s an unreasonable conclusion to come to. Still, I think that also ignores a lot of the very real barriers people get stuck on.
There are entire industries dedicated to helping people achieve their goals and they aren’t super accessible for a majority of people for a myriad of reasons (be it monetary, geographically, socially, etc…). I could see a world where a specialized LLM could fill that gap and raise the floor for people who may not be able to work with a personal trainer or life coach. I’m sure many fitness companies are already working on getting an LLM-based coach integrated into their apps.
The experiment was a success and it went as smoothly as I could have hoped. I got a training plan, followed it, and hit my goal. I’d be curious to see how well it works for fields that don’t have training plans so ingrained in their culture like exercising has.