Physical Therapists Using Clinical Analysis To Discuss The Art And Science Behind Running and The Stuff We Put On Our Feet

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When ChatGPT went public it immediately sparked conversation about how this technology could potentially radically change the way we know writing. Content creators suddenly have at their disposal a very intelligent system capable of generating endless material daily. With the right about of cues, it could write just about anything at a very baseline level. We naturally wondered what affect ChatGPT may end up having in our space. Obvious an AI can't run in the physical shoe, but we wondered how nuanced it could write when enough information was populated on the internet. Using Nike's most popular everyday trainer, the Pegasus, as a template, we decided to try and let ChatGPT write a full review of the shoe to see how well it could perform. We know the Pegasus 39 has a wealth of reviews online, so we were interested in seeing how it performed. Here is the result, with editor's notes along the way with some thoughts.

A Review of the Nike Pegasus 39 as Tested by ChatGPT: Can AI Replace Doctors of Running?
By Content Manager Bach Pham and ChatGPT



The Nike Pegasus 39 running shoe is one of Nike’s most popular running shoes. It is designed to provide cushioning, support, and stability to help runners of all levels reach their goals. The Pegasus 39 features an updated version of the original Pegasus 34, featuring the React midsole for energy return and cushioning. In this review, we’ll discuss the fit, performance, stability, and recommendations for the Nike Pegasus 39.

Editor's Thoughts: ChatGPT did a good job of setting up a basic framework, but then went off into the rails a bit with the Pegasus 34 reference. We did ask it to mention React in the review, which it delivered here. Overall it provided a pretty darn basic, no-frills intro.


The Nike Pegasus 39 fits true to size. It features a supportive upper with a synthetic overlay for additional support and breathability. The heel has a contoured fit, providing a secure and snug fit. The midfoot features Flywire cables for a secure fit and lockdown. The toe box is roomy and allows for movement and flexibility. The lacing system is traditional and allows for a personalized fit.

Editor's Thoughts: ChatGPT did a basic, but not terrible job on fit. Probably the most impressive part was pulling flywire into the review, which we did not identify as something it needed to include. The AI did attempt to be a bit descriptive, and for some people this info might actually be just enough. We're not sure where the contoured fit comment came from though.

In other attempts at fit, we actually saw a few different variations on how it fit according to ChatGPT. In some cases it said it hugged the foot, while others it said it was a socklike fit. It always leaned in a positive tone overall, just in different sayings.


The Nike Pegasus 39 delivers excellent performance. The React midsole provides energy return and cushioning, making every run feel comfortable and responsive. The outsole features a modified waffle pattern for traction and durability. The midsole also features Nike Zoom Air technology, providing additional cushioning and responsiveness. The upper is lightweight and breathable to keep the foot cool and comfortable.

Editor's Thoughts: The AI didn't really deliver a developed performance section. We tried some longer formats of this, encouraging different word lengths, but it mostly reorganized the information and expanded it slightly without offering more thoughts. It definitely leaned into buzz words. The addition of waffle pattern and Zoom Air was interesting, again two things we didn't prompt for it to call for. It often would highlight the durability of the outsole in particular.


The Nike Pegasus 39 provides great stability. The midsole features a stabilizing foam wedge, which helps to reduce pronation and provide a smooth transition. The outsole also features a modified waffle pattern that provides traction and stability. The midfoot features Flywire cables for a secure fit and lockdown. The upper also provides additional stability with its synthetic overlays.

Editor's Thoughts: We were trying to figure out where stabilizing foam wedge came from, and it seems like it aggregated some former Nike stability shoe reviews to grab the foam wedge. It's kind of neat of that it pulled some minor stability elements from the outsole and upper. This section also highlights the AIs tendency to be relatively positive about its thoughts on products. We encouraged it to write about a few other shoes, and in every scenario it only contained the positive elements of the footwear.

Thoughts as a DPT: Heel to Toe Drop 101
By ChatGPT

Heel-to-toe drop, also known as offset or heel-to-toe differential, is the measurement of the difference in height between the heel and the forefoot of a running shoe. It is measured in millimeters (mm) and is usually printed on the sole of the shoe. Heel-to-toe drop is important in running shoes because it affects the way a runner strikes the ground. It can also affect the way a shoe fits and how comfortable it is to wear. 

A lower heel-to-toe drop (0 to 6 mm) is typically associated with a more natural running form, as it encourages a more forward-leaning posture and a midfoot or forefoot strike. This type of running style is beneficial for runners who are looking to improve their efficiency, as it reduces the amount of impact on the body and helps to maintain good posture. 

A higher heel-to-toe drop (8 to 12 mm) is often preferred by runners who are looking for cushioning and stability. This type of running shoe encourages a more heel-strike running form and is beneficial for those who are prone to overpronation or need extra cushioning. 

Ultimately, the right heel-to-toe drop for running shoes is determined by an individual’s running form, goals, and preferences. There is no one-size-fits-all solution, so it’s important to find the right shoe for your running style.

Editor's Thoughts: We thought it would be fun to attempt to get ChatGPT to write a DPT section, so we chose a bit of a generic topic. It basically aggregated simple heel-to-toe drop articles word for word. This is really where the program excels we found, finding a relatively often-written subject and collecting it into a compelling write up. For most people, you probably would have a pretty darn hard time distinguishing whether or not anyone, including us, wrote this. (PS: there are many nuances to drop here that is missing.)


The Nike Pegasus 39 is a great choice for runners of all levels. It provides cushioning, support, and stability for a comfortable and responsive ride. The React midsole provides energy return and cushioning, and the outsole features a modified waffle pattern for traction and durability. The upper is lightweight and breathable for a comfortable fit. We highly recommend the Nike Pegasus 39 for runners who want a versatile and comfortable running shoe.

Editor's Thoughts: We had a hard time encouraging the program to provide real recommendations on how to change the shoe. It just went straight towards recommending who the shoe is for.


The Nike Pegasus 39 is designed for runners of all levels, ranging from casual joggers to competitive athletes. It features a lightweight, breathable mesh upper with Flywire cables for a secure fit and a soft foam midsole for cushioning. The shoe also has a durable rubber outsole for added traction and stability.

Editor's Thoughts: We thought the first line was pretty funny in the range of runners (a classic comment for Pegasus advertistng). It did do a nice job of providing a concise summary. The AI certainly doesn't give very personal thoughts, but as far as spitting out a review that could be hard to discern from many on the internet, it doesn't feel far off from some we've seen.


Fit: B+ (The Nike Pegasus 39 is said to fit true to size, with a comfortable and snug fit. The toe box is narrower than previous versions of the Pegasus, so those with wider feet may need to size up or consider a different shoe.)
A- (The Pegasus line is known for its versatility and ability to handle a variety of running activities, from easy runs to speed workouts. The Pegasus 39 features a React foam midsole, which provides a responsive and cushioned ride. Some reviewers note that the shoe can feel a bit heavy compared to other running shoes.)
Stability: B- (The Nike Pegasus 39 is not marketed as a stability shoe, but the midsole and outsole provide some support and stability for neutral runners. However, if you have specific stability needs, you may want to consider a different shoe.)
Personal: B (This category is subjective and dependent on individual preferences and needs. Some reviewers love the Pegasus 39 for its comfortable fit, cushioning, and versatility, while others prefer other running shoes.)
Overall: B+ (The Nike Pegasus 39 is a solid running shoe that offers a comfortable fit, versatile performance, and decent stability. It may not be the best option for those with wider feet or specific stability needs, but it is a good choice for neutral runners who want a shoe that can handle a variety of running activities.)

Editor's Thoughts: At first, this grading system didn't work at all for us. The ChatGPT kept giving all A's. We actually came back the next day for grades and found a more detailed, highly nuanced grading system for the ChatGPT after we just subtly changed a bit of our asks. It actually compiled a series of data to formulate actual grading which felt fairly accurate. It's pretty eerie how precise it hits some of the notes.


Overall, ChatGPT did exactly what we thought it would: take all reviews of the Nike Pegasus 39 and aggregate it into a slim, concise review. Based on various test we tried, it doesn't have the capacity to formulate its own opinions on a shoe. We tried coaxing it to give opinions, but it solely relied on pulling information from the internet to provide its thoughts. We also had it try to write shoe reviews for shoes that haven't come out yet, but it basically pulled back to other products in the brand's lineup and combined buzzwords. For instance, we asked it to review the Saucony Endorphin Speed 4. It pulled not only prior Endorphin Speed reviews, but also things like EVERRUN midsole from older shoes.

Despite its apparent limitations in writing this review, it is pretty eerie how quickly it was still able to put down what you've seen here. The system is fast and highly intelligent. We were able to provide different keywords to generate fairly nuanced thoughts on a variety of subject. The more information it was provided, the more sophisticated its writing immediately became. With some work, it clearly is capable of pulling off a review that feels almost genuinely written. We know from testing the Nike Pegasus 39 for example what elements it is missing, but we could see how someone could just fiddle with the system and generate a bunch of shoe review writeups that would be hard to discern from others which is pretty darn scary. The grading section in particular showed how it could really aggregate opinions to formulate a painting of how the internet feels about the Pegasus 39.

Usage-wise, there are certainly some positives we've learned from the system. It's a great writer's block tool when you are trying to frame something and need a jump start. It does a great job with brainstorming ideas when you are in a rut, aggregating popular subjects for you to help generate a focused topic or concept. We did find that it was a very sharp social media content creator in particular. It would be very hard to separate the posts it makes about products from what is all over Instagram and Twitter. We're starting to question if half the content we see on Instagram right now in the shoe world isn't from ChatGPT.

Though we're not worried about ChatGPT taking over the review industry due to its inability to physical test products, we are scared about how people could take advantage of it to spread a lot of running misinformation. People could use it for general running content without taking time to check the information and the source of the info. We recommend that you take the time to get to know where you get your information in the future and make sure you know it's from a reputable source that is providing accurate information and not a ChatGPT aggregate that may or not may not be true.


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