Abnormal blood lactate accumulation during repeated exercise testing in myalgic encephalomyelitis/chronic fatigue syndrome, by Katarina Lien, Bjørn Johansen, Marit B Veierød, Annicke S Haslestad, Siv K Bøhn, Morten N Melsom, Kristin R Kardel, Per O Iversen in Physiological reports vol 7, issue 11, June 2019 [Published: 03 June 2019] https://doi.org/10.14814/phy2.14138
Post‐exertional malaise and delayed recovery are hallmark symptoms of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Studies on repeated cardiopulmonary exercise testing (CPET) show that previous exercise negatively affects oxygen uptake (VO2) and power output (PO) in ME/CFS. Whether this affects arterial lactate concentrations ([Laa]) is unknown.
We studied 18 female patients (18–50 years) fulfilling the Canadian Consensus Criteria for ME/CFS and 15 healthy females (18–50 years) who underwent repeated CPETs 24 h apart (CPET1 and CPET2) with [Laa] measured every 30th second.
VO2 at peak exercise (VO2peak) was lower in patients than in controls on CPET1 (P < 0.001) and decreased in patients on CPET2 (P < 0.001). However, the difference in VO2peak between CPETs did not differ significantly between groups. [Laa] per PO was higher in patients during both CPETs (Pinteraction < 0.001), but increased in patients and decreased in controls from CPET1 to CPET2 (Pinteraction < 0.001).
Patients had lower VO2 (P = 0.02) and PO (P = 0.002) at the gas exchange threshold (GET, the point where CO2 production increases relative to VO2), but relative intensity (%VO2peak) and [Laa] at GET did not differ significantly from controls on CPET1. Patients had a reduction in VO2 (P = 0.02) and PO (P = 0.01) at GET on CPET2, but no significant differences in %VO2peak and [Laa] at GET between CPETs.
Controls had no significant differences in VO2, PO or %VO2peak at GET between CPETs, but [Laa] at GET was reduced on CPET2(P = 0.008).
In conclusion, previous exercise deteriorates physical performance and increases [Laa] during exercise in patients with ME/CFS while it lowers [Laa] in healthy subjects.
Funding Information: The Norwegian Extra Foundation and The Norwegian ME‐Association.