Normative data for the 10-min Lean Test in individuals without Orthostatic Intolerance

Normative data for the 10-min Lean Test in individuals without Orthostatic Intolerance

Abstract
Background: Orthostatic intolerance syndromes such as Orthostatic Hypotension (OH) and Postural Orthostatic Tachycardia Syndrome (PoTS) are common symptoms seen in post-infection conditions and other neurological conditions with autonomic dysfunction. The 10-minute National Aeronautics and Space Administration Lean Test (NLT) is an objective clinical test used to assess these symptoms and direct management. There is, however, no robust literature on normative data for this test, particularly from a younger population.

Aims: The aim of this study was to produce a healthy control data set for NLT, which can be used for comparison with the patient population with health conditions.

Methods: Individuals recruited into the study had no history or symptoms of orthostatic intolerance; autonomic dysfunction; post-infection conditions (such as long COVID); or other neurological conditions with hemodynamic instability. Participants were primarily recruited from the general population in a metropolitan city. All participants underwent a standardised NLT. Lying Blood Pressure (BP) and Heart Rate (HR) after 2 min of lying down supine was recorded, followed by BP and HR recordings at every minute of standing (leaning against a wall) up to 10 minutes, along with recording patient-reported symptoms at each time point.

Results: A complete dataset was available for 112 individuals (60.7% Female, 39.3% Male). The population was 61.6% Caucasian, 8.0% Asian, 3.6% Black/Caribbean, 9.8% Mixed, and 17.0% Other; the mean age was 35.3 ± 15.1, with a BMI of 24.8 ± 4.0; 30.6% of individuals had a background medical condition, but none of the exclusion criteria. During NLT, upon standing, the average change of HR was an increase of 9.89 ± 8.15bpm. The sustained HR increase (HR increase sustained at two consecutive readings) was an average of 6.23 ± 6.94bpm. The predominant response with BP was an increase of systolic BP, with the average initial increase being 7.55 ± 10.88mmHg. None of the participants met the diagnostic criteria for symptomatic OH or PoTS during NLT.

Conclusion: For the first time in the current literature, NLT data from a relatively younger healthy population without orthostatic intolerance have been gathered. This normative data will help interpret NLT findings in younger patients with Orthostatic Intolerance better and be useful in managing dysautonomia in specific conditions.



https://www.medrxiv.org/content/10.1101/2025.05.06.25327047v1.full.pdf

 

@ME/CFS Skeptic they seem to imply very small increases in HR and the authors seem to imply that only a single person had a 30BPM increase. That seems in stark contrast with the rest of the literature, doesn't it?

 

I suppose it would have been nice to know something about the fitness of the participants but given that many can be considered to be overweight it seems very reasonable to assume that the results aren't primarily driven by an overly fit cohort.

 

Yes, a bit. The main caveat is that past literature was mainly about head-up tilt table testing which usually show higher heart rate increases upon standing than this (NASA) lean test.

In this study only 4 out of 112 had abnormal tests, including one with a heart rate increase > 30 bpm and 2 with persistent tachycardia above 120 bpm. So that isn't much.

The study is part of the LOCOMOTION study which previously reported quite low POTS rates of 7% in Long Covid patients. Perhaps this is because the authors required symptoms during the standing tests for a diagnosis of POTS which isn't usually required (you don't have to have symptoms during the test, only 8% of controls had this).
https://onlinelibrary.wiley.com/doi/10.1002/jmv.29486

 

But these are healthy controls, so you'd expect small increases in HR and very few to none meeting PoTS criteria. Unless I am misinterpreting your post...?

 

From my experience with a tilt table test, the details of the execution are very important.
This concerns the way the feet are reaching the bottom "panel" of the table.
If your feet are levitating (shouldn't be I think), if they are firmly on the panel or in between.
Depending on the "pressure" of your feet to the foot panel it's quite easy to activate the venous pump of the legs while being strapped.

 

Don’t you get told to not move or do anything at all to avoid any pumping?

 

That is also what I initially thought, but my impression has changed a bit, meaning that I was indeed not expecting such small increases, at least not at the rate seen in this paper with only 1/112 having a 30 BPM increase. My impression had been that an increase of 20 BPMs can be fairly normal for healthy people and have heard of plenty of healthy people that have a higher increase and since transient tachycardia right after standing is also normal I would have expected more false positives at least at one timepoint.

According to what I've seen in the literature when it comes to the head-up tilt tests there seem to be quite a few false positive, in the sense of OT (30 BMP increase) being somewhat common, from what I recall this was also seen in some of the HC's in the intramural study. On the other hand fewer people diagnosed with POTS meet the 30BPM threshold on the NLT than the HUT according to some studies and generally the HUT seems to cause a greater HR increase but the results are not always consistent as there are some studies studies (this is a LC study) where apparently the NLT caused a greater HR increase. Presumably there are always small differences in how these procedures are carried out that may be shifting the results of the studies in one way or another.

I recently shared a study where some researcher call for the abortion of the HUT for similar reasons.

This paper would seem to indicate that false positive wouldn't be a problem for the NLT and seemingly even people with varying degrees of fitness. But I don't think there is data for people with very low activity levels which might complicate the picture.

After all the recent results and the blog by @ME/CFS Skeptic I had pretty much concluded that both the NLT and HUT are rather meaningless in the context of ME/CFS and LC, presumably because POT doesn't capture the nature of OI seen in these conditions, but if the values from the above study are in any way representative than perhaps the NLT would have some limited value.

 

From what I understand you should not pump, yes!

However, in fact, during my TTT the nurse told me to pump every now and then. The first time I mindlessly did it, then afterwards thought about it and ignored him.

 

My legs startet shaking after 1 minute of NLT, but my measurements were sky high regardless. Got to stop after 3 minutes.

 

Lucky you! Mine was aborted after 20 min when besides 140 bpm my blood pressure dropped like hell and I nearly fainted.

 

I think I got lucky because I had an increase after only two minutes, and the cardiologist knew a bit about ME/CFS so he knew I was pushing way past my limits already.

 

The lady (who did it for a long time) didn't tell me.
Just that I should be in between firmly standing and not.
Though I also think you can't completely control it.

But it was clear she was not that well versed with POTS, thought it was always symptom free lying down.
And suspected POTS is only a (minor?) part of the TTT measurements done there.

My legs also started shivering fast btw..

For me it's obvious that POTS HR increase is a real thing. The measuring technique can be discussed but for me it started so abrupt shortly after a vaccine that it was obvious.

 

I don’t think that’s up for debate. The question is if HR is a good measure, and if it’s even tied to the symptoms or just downstream effect of something else.

And increased HR when standing can happen for a number of reasons, so it might not be a good indicator of pathology, which is what you’d want to know to try to eventually treat the issue.

 

Isn't that why it's commonly reffered to as a syndrome? Same diagnostic criteria fulfilled, possibly many different root causes. Like ME/CFS.

And can't you have a downstream effect that is quite indicative of a disease without being significantly tied to the symptoms? Me being upright doesn't change that much compared to my baseline, but when your baseline is already very bad an additional 10% becomes very important.

I just think that strapping the S from the POTS is not helpful within the medical field. Imo it makes the impression of questioning the long fought credibility of the diagnosis that in practice can be very helpful for patients (recognition by insurance, medical providers, ...).

 

POTS is far more prevalent than ME/CFS, so you can’t really compare the two. POTS is almost like lumping all coughing caused by exertion together.

There is a difference between recognising the disability experienced and using speculative labels and wild guesses about pathology. hEDS suffers from the same issues - it’s too broad and vague and the patients probably have something else wrong with them. (Edit: some other pathology causing their issues, than EDS).

For POTS, it would be far better to just use OI - orthostatic intolerance and focus on the level of disability experienced rather than HR.

People have adopted the POTS label because it acknowledges their disability. So it’s understandably why they are opposed to criticism of the concept. But I think they could has achieved the same recognition, or even more, if the opportunistic doctors stayed out of it and forced POTS as a clinical entity. Because serious people are put off by pseudoscience and wildly speculative claims.

 

Going by US numbers shouldn't it be quite equal (didn't find the specific literature for CCC/ICC)?
https://me-pedia.org/wiki/Prevalence_of_myalgic_encephalomyelitis_and_chronic_fatigue_syndrome
https://www.dysautonomiainternational.org/page.php?ID=30

For the second point (and the rest), I respectfully disagree, without going into details because that would open a huge discussion.

I don't think it's inherently bad to label "diseases" like that from a scientific point of view.
For example, New Daily Persistent Headache (NDPH) is a syndrome with obviously many different root causes. But you have to start somewhere - and it helps with tracking and measuring the syndrome e.g. via ICD codes. With the final goal of getting rid of the diagnosis after having established the distinct sub-diseases.

 

That page suggested a prevalence of up to 2 % for POTS.

I think ME/CFS is roughly 0.5 %?

That’s kind of what we do here - dive into the nuances of the arguments.

But it’s probably better to do it here:
https://www.s4me.info/threads/orthostatic-intolerance-in-pwme-pots-nmh-discussion-thread.1976/

 

I thought error bars on a graph indicated 1 x standard deviation. The sustained increase in heart rate was reported as 6.33 ± 6.82bpm where 6.82 is the standard deviation from the mean of 6.33.

Why then are the error bars in the graph so small?

 

Those are standard error bars not standard deviation bars. sd tells you about variation in the sample, se tells you about variation if you drew a bunch of samples from your sample. Those graphs are clearly made in excel and I believe excel does standard error as the default!