Is this CPET profile typical for ME/CFS? Early anaerobic threshold, lactate 24 mmol/L, normal muscle biopsy

T

tommybrand

Established Member
Hello,

I'm looking for some perspective on whether my CPET findings are typical for ME/CFS, or whether they point more strongly toward another type of metabolic or mitochondrial problem. Any inputs would be appreciated. Please delete my post if its breaching a forum rule.

I've had exercise intolerance since age 17 following mononucleosis/EBV. I have a ME/CFS diagnosis with significant PEM, cognitive dysfunction, fatigue, and increased exercise intolerance since 2019 after an infection while traveling in SE Asia. Extensive neurological, rheumatological, and metabolic workups have largely been unrevealing. Muscle biopsy reported as normal.

However, my CPET showed:
  • VO₂peak: 3118 mL/min (79% predicted)
  • VO₂/kg: 43.9 mL/kg/min (92% predicted)
  • Anaerobic threshold at 29% of predicted VO₂max
  • Peak lactate: 24 mmol/L
  • Peak pH: 7.16
  • Normal pulmonary function and oxygenation
  • The interpreting physician suggested a possible peripheral limitation and recommended consideration of muscular, metabolic, or mitochondrial pathology.

My question is:

How unusual are findings such as lactate 24 mmol/L, pH 7.16, and a very early anaerobic threshold in ME/CFS patients? Are values like these still seen within the spectrum of ME/CFS, or could it be considered unusually severe and more suggestive of a primary metabolic/myopathic/mitochondrial disorder despite a normal muscle biopsy?

I've been trying to understand my results, and when I research or ask AI models, they seem to say this is abnormal for an ME/CFS patient, yet the doctors at my hospital say this is expected for ME/CFS.

My main concern is that I don't actually have ME/CFS, but something else that they have potentially missed or didn't check thoroughly enough.

Appreciate any inputs!
 
As far as I know there are no specific documented abnormalities for any of these variables in ME/CFS. I am not familiar with reference ranges so do not know if these values are within those. I don't think anyone here is in a position to advise on the significance of these findings. They may indicate another condition but you need to discuss that with your health care professionals.
 
I can only say this would fit my profile well too, though I haven’t done a CPET. I got ME/CFS following EBV. I’ve monitored lactate values before/during/after triggering PEM episodes on purpose. Values can then reach up to 20mmol/L even at rest, but there is no 1-1 correlation with perceived exertion before triggering PEM.

I had some improvement in function after the initial 6-12 months of illness and tried running for a while, which ultimately lead to deterioration. I found while trying to exercise that my anaerobic threshold was shifted to a much lower pace than before I got ill, though it barely triggered increased breathing. In other words, the practical outcome of your relatively low threshold at 29% of vO2max, pointing toward a peripheral bottleneck.

Don’t know if this helps, but I certainly fit the CCC.
 
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