Race Information

• Name: Phoenix Half Marathon
• Date: December 13, 2025
• Distance: 13.1
• Location: Phoenix, AZ
• Website: https://phxmarathon.com
• Strava: https://www.strava.com/athletes/43172262
• Time: 1:28:53

Goals

Goal	Description	Completed?
A	Sub 1:28:00	No
B	Sub 1:29:00	Yes
C	Sub 1:30:35	Yes

Splits

Mile	Time
1	6:46
2	6:56
3	6:43
4	6:42
5	6:59
6	6:54
7	6:46
8	6:41
9	6:32
10	6:40
11	7:18
12	6:41
13	6:38
13.1	6:40

| 1st Half | 44:39 | 2nd Half | 44:13

Background

I am a 45-year-old man (150 lbs) with several years of casual running experience. I have run 9 half marathons and 3 full marathons over the course of the past 20 years. Now squarely in my mid-40s, I’ve decided to combat my mid-life crisis by trying to notch a few more PRs while I can.

I ran my first full marathon in NYC in November 2024 (3:26:31). I ran the REVEL White Mountains Marathon in May 2025 (3:07:39). My goal of a new PR at the 2025 Berlin Marathon was foiled by heat (finished at 3:20:15).

Going into Phoenix, my PR in the half marathon was 1:30:35, which I claimed this summer during the best training run of my life.

This year I broke 20 minutes in the 5K and broke 40 minutes in the 10K. I decided to end my racing year in Phoenix to both seek redemption for Berlin and take crack that elusive 90-minute barrier in the half marathon. I also wanted to use the race to assess the feasibility of a sub-3:00 marathon attempt in 2026.

Training

I followed slightly modified Pfitz 12/63 plan for this training block. I also dabbled with ChatGPT “coaching” to supplement the Pfitz plan. More on that below.

I took a recovery week after Berlin with no running. That left 10 weeks (instead of the 12 contemplated in the Pfitz plan) to bounce back for a short-ish build toward this half marathon. I basically just started in Week 3, instead of Week 1. The plan included a bit more focus on threshold and speed work (1000m and 1200m intervals on a few occasions), and shorter long runs (peak was 16 miles). But I was over 60 miles for at least 4 weeks, which was a lot for me and actually more average weekly mileage than in my previous marathon builds.

I trained based on an “A” goal time of 1:28:00. Here is a breakdown of the rough pacing I used as a guide during this short build based on my perceived level of fitness and goal time:

Pace	Target Heart Rate	Minutes/Mile
Marathon Pace	82-88% Max HR	7:00-7:09
Half Marathon Pace	82-90% Max HR	6:43-6:56
Lactate Threshold	82-91% Max HR	6:26-6:39
Long Run	75-85% Max HR	7:46-8:29
General Aerobic	72-81% Max HR	8:08-8:50
Recovery	<76% Max HR	>9:11

I paid more attention to heart rate than I have in the past. Unfortunately, with the onset of colder weather (I live in the northeast of the US) my Apple Watch became famously unreliable for this. That meant my primary metrics were pace and feel.

I also did a better job slowing down during general aerobic and recovery runs. Probably still not as slow as many might recommend but I do think I’m trending in the right direction, trying to reserve higher intensity for speed days. That said, I did tend to infuse increased effort into long runs for which I frequently aimed for some kind of progression pacing. Because of that, my long runs were closer to 7:30-7:55/mile average.

I did two “tune up” 10K runs that I tried to target near race pace—one 4 weeks out and one 2 weeks out. I broke 40:00 in each those, 39:35 and 39:45, respectively. Those efforts were helpful to boost confidence because I have to believe—rightly or wrongly—that I could go quicker under actual race conditions, as opposed to self-imposed “race-effort.”

The LT and interval workouts were challenging and feel like they helped build my fitness but I think I would prefer more half-marathon-pace work than the Pfitz plan contemplates. The only half-marathon-pace workout in the entire plan was the dress rehearsal during race week, where I did just two miles at race pace. I understand the theory that the quicker LT runs and interval sessions at 5K pace are meant to make half-marathon pace feel easier on race day. (And that certainly felt accurate for me on race day.) But without repeated half-marathon-pace workouts, I felt less accustomed to that rhythm and less confident about my ability to actually hold that theoretical pace on race day.

I tapered for approximately two weeks. As typical for me, I felt sluggish during the taper. Taper for me is also typically riddled with self-doubt. That was certainly the case again this time. Probably easier said than done, but it this is something I would like to mitigate in the future.

Assessing Potential and Building Confidence - Pace Calculators and AI

Identifying training paces and potential for race paces are huge variables that cause me stress, confusion, and uncertainty. I use a very imprecise amalgamation of prior races, pacing calculators and charts (e.g., Pfitz, McMillan), VDOT calculators, Strava predictions, and my gut to determine what I think I am capable of for a given race at a given place and time in my life. All that is further confused by ongoing questions about what I can reasonably expect from the increasingly aging body of a masters runner.

I also decided to add ChatGPT “coaching” into the mix. I was truly just experimenting and took much of it with a heavy grain of salt. Whenever a suggestion departed markedly from what I had already contemplated in the Pfitz plan, I stuck with Pfitz.

What I liked:

• I was able to upload a bunch of historical data that helped lay a better foundation for who I am as a runner.

• I was able to upload data from individual workouts, which yielded some immediate feedback and a sounding board about what to make of that workout and whether it was consistent with my stated goal or if it signaled that I should consider modifications.

• I was able to plug in variations of the planned schedule to get a sense about what changes might or might not be wise.

• I felt like I was engaging with a coach that was invested in my training (even though, as noted below) that was far from reality.

What I disliked:

• As has been widely reported, ChatGPT is annoyingly sycophantic. It almost always frames data or questions in the positive—suggesting that I am always doing everything right.

• It’s plans or proposals frequently change from day to day, which often required me to request clarification of the inconsistencies.

• Both of the above points made it made it very hard to give any weight to its responses to my questions or to any of its assessments about my fitness, potential, or feasibility of my goals.

My experience with the Strava Performance Predictions was similarly unsatisfying. For reasons I can’t explain, I feel invested in seeing the race prediction times fall but I’m convinced that, at least for me, they overestimate my potential at every distance. For example, in the weeks leading up to the half marathon, Strava consistently predicted 1:26:xx. Based on my performance in Phoenix, that feels pretty significantly out of reach at my current fitness level.

Injury Prevention and Gear

Despite intentions to do more, I did only the bare minimum in terms of strength training. I was able to dodge any injuries during the block but I definitely think a lack of structured strength training remains among the most notable deficiencies in my training routine.

I train almost exclusively in the Hoka Skyward X. I have gout and hallux rigidus (stiff big toe arthritis). The stiff plate, aggressive rocker, and cushioning have helped mitigate the symptoms of those conditions. Prior to finding this trainer, I experienced recurring and sometimes debilitating pain in each of my big toes.

I did LT workouts in the Hoka Cielo X1 and New Balance SC Elite. For intervals, I used the Nike Vaporfly 3. I raced the half marathon in the Nike Alphafly 3.

Race Registration

I had a pre-planned trip to Phoenix scheduled for the weekend of December 13 so I decided to register for this race after Berlin. The cost for the half marathon was $149. For what it’s worth, they offered Black Friday registration discounts, which I missed. Might be something for locals to consider in the future if you don’t have to worry about travel or accommodations.

Travel, Accommodations, and Pre-Race

My wife and I traveled to Phoenix on Thursday 12/11. Coming from the east coast we benefited from a two-hour time change. That made getting to bed the night before the race and waking up on race morning much more comfortable.

We attended the race expo on 12/12 at around 2:00 p.m. Pretty standard. Not very crowded. No standout swag or samples. But it was efficient and easy. I also picked up a pacing bracelet.

I did a typical carb loading and hydration routine for the few days leading up to the race. In theory, this felt less consequential than it does for a full marathon but I still took it seriously—pasta, bread, bagels, bananas, Gatorade and water.

Pre-Race

The race was scheduled to start at 7:15 a.m. I arrived to the staging area at 6:15 a.m. The weather was crisp—about 50F. Bag drop closed at 6:45 so I was happy that I had some old sweats to keep me warm and then toss at the start. I used the porta potties and then sipped on some Maurten 160 for about 40 minutes as I got my race shoes and kit ready to go. At about 7:05 we were directed to move toward the starting line, which was about a quarter mile or so away from the porta potties and bag drop. Made for a nice pre-race warmup jog.

With approximately 2500 runners in the half marathon, there were no corrals or staggered start times for this one. There were pacers for 1:25 and 1:30, both of which were essentially next to one another toward the front of the crowd. The race started promptly at 7:15 a.m.

Race

I thought the weather was excellent for a half marathon. At gun time, the sun was just starting to peek over the horizon. As the sun rose, there was also a light cloud cover that made the cool temps particularly pleasant.

I carried a single SiS gel and took Gatorade at a single station at around mile 5-6.

Miles 1-4

I opted to start with the 1:30 pace group. My plan was to stay with the pacer for around the first 5 miles and then evaluate whether I could trim the pace down from around 6:50-ish to 6:40-ish or quicker.

At 3.5-4 miles I broke slightly from the pacer. I was still settling in and didn’t feel like I quite hit my rhythm but I was feeling confident that I could move a bit more freely without tethering myself to the pacer.

Miles 5-7

I felt generally good through miles 5-7 but did have some doubts creeping in about whether I was a bit over zealous about what pace I could realistically maintain. Sensing that I was still ahead of the 90-minute pacer, I dialed back a bit and tried to get locked in without pushing further ahead.

Miles 7-10

I found that rhythm somewhere within mile 7 and maintained a steady state for the next couple miles. Was feeling solid and cautiously optimistic about my positioning. The pacing band indicated about a 30-second slowdown in pace due to a hill around mile 11. I wanted to respect that hill but I was also feeling skeptical about how tough it would be given my general review of the elevation profile.

Mile 11

My skepticism was misplaced. The hill was not the craziest I’ve ever tackled by any means (approximately 100 feet in elevation) but its location at mile 11 of an otherwise flat course made it feel somewhat more daunting than it otherwise would have. My pace dipped significantly here and although it didn’t burn me out entirely, it messed with the smooth rhythm I had locked in and eliminated any chance of hitting 1:28, which was already a long shot before the hill.

Miles 12-13.1

The downhill here was also significant but it was difficult to capitalize on for a few reasons. The section was particularly clogged with slower 10K runners and walkers. That challenge was exacerbated because the downhill followed a fairly narrow and winding path which made it tough to just open up and let gravity carry me down. Finally, even if to a relatively minor extent, the gravel path offered less-than-optimal footing and traction, especially on tired legs. I was still able to get back to 6:40-ish pace here but in my mind I was banking on being at able to move even quicker to fully neutralize the time lost on the uphill.

To that end, the course also included a brief out-and-back with a hairpin turnaround in the last half mile. Again, standing alone, that turnaround can’t be “blamed” for a less-than-ideal pace through the finish but I do think that all those factors taken together at this late stage of the race did contribute to at least some slowdown not purely attributable to fitness.

Then it was thee end. I turned the corner and came down the final stretch fast and strong—at least according to the image in my head! I crossed the finish line consumed with that very special euphoria that fuels the desire for so many of us to keep signing up for the next race.

Post-Race and Overall Impressions

I recommend this one! The weather was nearly perfect, the logistics were smooth, and, even though crowds and cheering were more muted than in other races, the energy was still terrific. And the timing in December is such a nice way to wrap up a year on the roads!

Constructive criticism: The course is generally fast but in addition to the issues noted from mile 11 through the finish, there were also a few segments earlier in the race (perhaps 2-3 miles total?) that were on a loose gravel path as opposed to asphalt. It’s hard to quantify how much, if any, time is lost due to the “slippage” of a gravel path but, despite my effort to ignore it, I did notice it and it caused me some frustration—warranted or not. Likewise, several segments in the latter half of the race did feel a bit crowded with walkers who were occupying the entire width of path, which meant there was some weaving and traffic navigation that was less than ideal. I do think race organizers could mitigate some of this with some tweaks to the trajectory of the course, more strategic staggering of start times for each of the races, and some clearer guidance or regulation to keep a lane clear for passing runners throughout the course.

I did not get that reach of my “A” goal but I walk away with a new PR, breaking my prior best by nearly 2 minutes and taking third place in my age group. As I mentioned, I set 1:28 as my “A” goal for some clearer confirmation that a sub-3:00 marathon could be realistic for 2026. After Phoenix, whether that goal might be possible remains far from certain.

I’m registered for Boston and Chicago in 2026. My current plan is to continue to build my aerobic base and focus on strength training in the build toward Boston. Based on progress during the next several months, I will decide whether to aim for sub-3:00 or moderate to something closer to 3:05.

I feel good! I am grateful for my health and my mobility. I am proud of my commitment and what I have been able to accomplish. And I am as ready as ever to continue to push toward that next PR.

Cheers to you all. See you in Boston!

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