Oxygen uptake kinetics during postexercise recovery are impaired in long COVID-19 patients: a cross-sectional study, 2025, Zamorano-Vargas et al.

[SNT Gatchaman]

Oxygen uptake kinetics during postexercise recovery are impaired in long COVID-19 patients: a cross-sectional study
Zamorano-Vargas; Izquierdo; Ramírez-Vélez

No abstract.

Link (Revista Española de Cardiología (English Edition)) [Paywall]

 

[SNT Gatchaman]

Previously by these authors —

Reduced Autonomic Function in Patients with Long-COVID-19 Syndrome is Mediated by Cardiorespiratory Fitness (2024, Current Problems in Cardiology)

Maximal oxidative capacity during exercise is associated with muscle power output in patients with long coronavirus disease 2019 COVID-19 syndrome. A moderation analysis (2023, Clinical Nutrition ESPEN)

 

[SNT Gatchaman]

This study aimed to compare the cardiovascular effects of maximal graded exercise, specifically focusing on the previously unassessed impact of long COVID-19 syndrome on postexercise V̇O2 kinetics, compared with a group without a history of COVID-19.

This exploratory observational study involved 59 individuals (68% women) with a confirmed diagnosis of long COVID. Participants had mild or moderate symptoms, no history of hospitalization, and no prior heart or lung disease.

Edit to add baseline physical activity differences:

Overall physical activity, MET-min/wk (mean/SD)
Patients 1118.36 (1227.80)
Controls 2029.93 (1223.83)
p < .001

V̇O2 kinetics were calculated by subtracting resting V̇O2 from peak V̇O2 following 1-minute (V̇O2 R1), 2-minute (V̇O2 R2), and 3-minute (V̇O2 R3) rest intervals. The half-time of recovery of V̇O2 (T1/2 V̇O2 ) was defined as the time required for peak oxygen uptake (V̇O2 peak) to decrease by half.

Sex, body weight, height, body surface area, and BMI were comparable in the control group and the long COVID group.

The half-times of V̇O2 recovery are reported in figure 1B. All were greater in long COVID-19 participants than in controls (126 [90-160] vs 69 [57-93] s; P < .0001).

After peak exercise, V̇O2 recovery rates were significantly impaired in long COVID-19 participants compared with controls: V̇O2 R1 (20.88% [13.89-23.46] vs 26.72% [22.04-30.78]; P = .01); V̇O2 R2 (41.72% [35.64-47.87] vs 53.54% [48.08-58.79]; P = .002), and V̇O2 R3 (47.93% [42.70-56.91] vs 60.01% [55.08-64.75]; P = .001), figure 1C).

Previous studies have demonstrated a negative correlation between V̇O2 kinetics and V̇O2peak in individuals with lower fitness levels. Low exercise capacity is a hallmark of long COVID, significantly impacting daily life. Consistent with prior hypotheses, our findings confirm that long COVID is associated with altered V̇O2 kinetics. Specifically, long COVID-19 participants showed higher T1/2 V̇O2 values (∼90 to 160 s) compared with the typical range for healthy individuals (∼60-90 s), which closely matched the values observed in our control group.

These findings suggest that the traditionally assumed strong relationship between V̇O2 kinetics and V̇O2 peak may not apply universally throughout the fitness spectrum, as these 2 measurements may be influenced by different underlying mechanisms. […] suggests that both central and peripheral factors may contribute to exercise intolerance in these individuals. A T1/2 V̇O2 >150 s (75th percentile, equivalent to 50 s above of the control group) appears to be associated with lower peak V̇O2 (< 20 mL/min/kg), even during submaximal exercise.

 

[SNT Gatchaman]

 

[Hutan]

This study aimed to compare the cardiovascular effects of maximal graded exercise

Just to be clear, this isn't a reference to graded exercise therapy. This is the protocol used for the CPET, with the effort required to cycle increased over the length of the test.

 

[Hutan]

Looking at Figure A in SNT's post #4, you can see the resting VO2 increasing over the time of the exercise test to the Vo2 peak. And then they have measured how long each person took for their VO2 (their oxygen extraction) to reduce to half of the peak value.
There's a very clear difference in the peak VO2 between the LC and control groups, and in the time taken to recover to 1/2 VO2 max.

But, notice that the y axis doesn't have kg in the measurement, it's not actually the VO2 numbers that we know, it's not adjusted for the mass of the person.

And I assume that the chart is of one individual LC participant and one healthy control. So, perhaps the mean differences were not so starkly different?


If you look at Figure D in post#4, the differences are not nearly so exciting, suggesting that Figure A may have been cherry picked. There, they plot the VO2 max (per kg) versus the time taken to recover to 1/2 Max. It's a bit hard to differentiate the LC and control points. But, yeah, I don't think there is much of a difference in recovery times for a given VO2 max.

 

[SNT Gatchaman]

Yes, I think that's right. Here's the legend —

Figure 1. Oxygen uptake kinetics in controls vs long COVID-19 patients. A: line graph showing an example of oxygen consumption recovery after exercise in a control subject and a patient with long COVID-19. Oxygen consumption is plotted against time. The half-time of recovery of oxygen consumption (T 1/2 V̇O2 ) is the time between peak V̇o2 and 50% of peak V̇O2 at recovery; B: half-time of recovery of oxygen uptake (T 1/2 V̇O2 ); C: peak V̇O2 kinetics following 1-minute (V̇O2 R1), 2-minute (V̇O2 R2), and 3-minute (V̇O2 R3) rest intervals; D: association between peak V̇O2 and T 1/2 V̇O2 in both groups. Values are medians (bar), interquartile ranges, and individual data from minimum to maximum values (whiskers). V̇ O 2 kinetics were calculated as the peak V̇ O 2 minus resting V̇O2 after a 1 minute (V̇ O2 R1), 2 minute (V̇O2 R2), and a 3-minute (V̇O2 R3) rest. The half-time of recovery of V̇O2 (T 1/2 V̇ O2 ) was defined as the time needed for peak oxygen uptake (V̇O2 peak) to decrease by half.