u/JakeM520 — reddlx

I have a reoccurring problem that is destroying my race experience: after 30-60 seconds of descending steep/technical terrain, I feel a pain starting in the chest and moving to the back and diaphragm or high abdominal area. The pain just gets worse over time as I continue running, and it feels like stabs with every step, almost feeling that the force of the ground is returning in this back-core area.

In my latest race this pain peaked up to a point that when I finished I could not breathe easily. After crossing the line, for the next 15mins I could not speak normally because I felt out of breath, and I continued to feel pain in the ribs in my back every time I took a breath for the next 2 hours. While it started reducing in intensity, the pain didn’t go away until I slept and woke the next day.

This race was 40km/2500mD+ and it was essentially 22km uphill, then 18km downhill. I reached the peak after 3h20min feeling incredible, I was trying to not push that much and was waiting for the downhill section to really push the pace. Instead, I ended up doing 1h50m for the descend, full of pain, almost in tears at some points, having to walk and had almost decided to DNF. Info about the race:

I was ascending the first 3h20mins with an average of 174bpm, which is the middle of my zone 3 (Aet=167, LT = 182) measured with a chest strap, zones determined with evoke's method.
I was feeling really good until the top, nutrition was as planned (90g carbs / 500mg sodium / 1liter water per hour)
the first 2kms of descend were extremely technical with 550mD- (28% incline)

I have had this issue for at least 1.5 year, happening only in races, never in training and cannot figure out what it is. If it's a problem of intensity being too hard and thus the cardiovascular system fails, why does this happen on these steep parts of the course? Could it be a muscle weakness on the core/back/chest?

| TL;DR: I am a young trail runner with adequate experience and high volume training and I | have this reoccurring issue when racing: at 65–70% of the course, after reaching the highest | point and starting a steep technical descent, within 30–60 seconds I get stabbing pain | starting in the chest, moving to back and diaphragm. Gets worse with every step, forced | me to slow down. In last race, after finishing I couldn’t breathe/speak normally for 15min, | and had pain in ribs/back for the next hours.

I am in desperate situation with a problem that is reoccurring and is destroying my race experience both in performance and enjoyment.

Little background: 26 years old male, 174cm height, 72kgs, trail running experience of 3 years, mainly running distances between 20km/1500D+ and 40km/3000D+ (from 3 to 8 hours) and some longer solo runs of 60kms (10 hours). I have been training consistently: for the year 2025 I run 3.000kms, 361hours, 116.000m D+, for 2026 up until this point I have run 960kms, 110h, 35.000m D+. Plus, I have been doing running-oriented gym these years but haven’t been super consistent. Plus, I have some gym background of lifting for muscle strength and mass since I was 16y old. I am not built or anything, but I have some muscles and carry some fat mainly in the abdomen area.

This is a problem I have experienced in almost every race and it happens always at the same situation: when I am at about 65-70% of the course in terms of length or time duration (or at least 1.5 hours deep in the race) after reaching the highest point of the course and start to descend a rather steep technical downhill. Almost immediately, for example after 30-60 seconds of descending, I start to feel a pain starting in the chest and moving to the back and diaphragm or high abdominal area. The pain just gets worse over time as I continue running, and it feels like stabs with every step, almost feeling that the force of the ground is returning in this back-core area.

In my latest race this pain peaked up to a point that when I finished I could not breathe easily, for 15mins I could not speak normally because I felt out of breath, I felt a pain in the ribs in my back every time I took a breath for the next 2 hours and the pain (while it started reducing) didn’t go away until I slept and woke the next day. This race was 40km/2500mD+ and it was essentially 22km uphill, then 18km downhill. I reached the peak after 3h20min feeling incredible, I was trying to not push that much and waiting for the downhill section to really push the pace, but ended up doing 1h 50m for the descend, full of pain, almost in tears at some points, having to walk and had almost decided to DNF. Things to keep in mind: 1) I was ascending the first 3h20mins with an average of 173bpm, which is the middle of my zone 3 (Aet=167, LT = 182) measured with a chest strap 2) I was feeling really good, nutrition was as planned 3) the first 2kms of descend were extremely technical with 550mD- (28% incline)

I have had this issue for at least 1.5 year, and cannot figure out what it is.

a) Initially I thought it’s a stomach issue related to nutrition: I am doing 90g carbs / 500mg sodium / 1liter water per hour and never had stomach issues in training. In the past, there was one race I felt the exact same pain and in which I also felt somewhat bloated, so I thought the issue might be excessive water consumption. But in my last race I never felt bloated, nutrition felt balanced. But more importantly the pain never starts in the stomach area but higher and only once I felt the need to vomit.

b) I thought it might be a problem with weak core muscles, that’s why the last 6 months I implemented a core workout once per week. But in the latest race I had no problems in the abdominal area which would indicate that either this is not the problem, or that training the core solved part of the issue and the problem is weak chest/back. Which I find pretty strange considering the amount of strengthening I have done overall, when other athletes that are less built don’t experience pains like these, as far as I know. That’s where I definitely need opinions.

c) I even thought this might be a problem caused by my chest strap restricting breathing or pressuring the chest area somehow. In this last race, after 5mins of pain I completely removed the strap and nothing changed, the pain scaled as expected.

d) Another possible scenario is I am running all my races in a really intense effort, always at mid zone 3 or above. But then, I cannot understand why I am not blowing up my legs and the restriction of speed doesn’t come from them but from the chest/back pain.

Thanks for reading all the way, apologies for the long post but I wanted to provide as much information as possible from the get-go. I am really looking forward to listen opinions, similar experiences or suggestion on how to move forward and solve this issue.