Physiological measures in participants with chronic fatigue syndrome, multiple sclerosis and healthy

[A.B.]

Physiological measures in participants with chronic fatigue syndrome, multiple sclerosis and healthy controls following repeated exercise: a pilot study.

PURPOSE:
To compare physiological responses of chronic fatigue syndrome (CFS/ME), multiple sclerosis (MS) and healthy controls (HC) following a 24-h repeated exercise test.

METHODS:
Ten CFS, seven MS and 17 age- and gender-matched healthy controls (10, CFS HC; and seven, MS HC) were recruited. Each participant completed a maximal incremental cycle exercise test on day 1 and again 24 h later. Heart rate (HR), blood pressure (BP), rating of perceived exertion (RPE), oxygen consumption (V˙O2), carbon dioxide production and workload (WL) were recorded. Data analysis investigated these responses at anaerobic threshold (AT) and peak work rate (PWR).

RESULTS:
On day 2, both CFS and MS had significantly reduced max workload compared to HC. On day 2, significant differences were apparent in WL between CFS and CFS HC (93 ± 37 W, 132 ± 42 W, P<0·042). CFS workload decreased on day 2, alongside a decrease in HR but with an increase in V˙O2 (ml kg min-1 ). This was in comparison with an increase in WL, HR and V˙O2 for CFS HC. MS demonstrated a decreased WL compared to MS HC on both days of the study (D1 81 ± 30 W, 116 ±30 W; D2 84 ± 29 W, 118 ± 36 W); however, patients with MS were able to achieve a higher WL on day 2 alongside MS HC.

CONCLUSION:
These results suggest that exercise exhibits a different physiological response in MS and CFS/ME, demonstrating repeated cardiovascular exercise testing as a valid measure for differentiating between fatigue conditions.

https://www.ncbi.nlm.nih.gov/pubmed/28782878

 

[Valentijn]

So CFS and MS do worse compared to their healthy matched controls on a single CPET, and on the 2nd CPET as well. But the MS patients do a bit better on their 2nd CPET compared to their first one, while CFS patients do worse. Nothing new, but it's always great to see independent replication.

 

[A.B.]

Surprisingly to me CFS patients did a little better on VO2 and VO2max on the second day, but worse on other measures. It seems that measuring the drop in function on the second day isn't that straightforward. Maybe it depends on the exercise protocol used, activity level on previous days, and things like that. MS patients were also an average of 19 years older than the CFS patients making direct comparison difficult (both had age matched control though).

 

[ash0787]

similar been done before, they could try measuring relevant by-products / metabolites after 30 minutes of exercise or try using a high grade thermal camera to look at heat generation / distribution / circulation etc

 

[Simon]

Needs a bigger study to replicate these findings, but I think this is the first study to show other diseases are different (outside cardiopulmonary ones), a key step in showing these findings are specific to mecfs.

 

[Valentijn]

Full text at http://sci-hub.io/10.1111/cpf.12460 - It's a nice read, even if not understanding the technical bits. They really seem to understand what ME is, that PEM is a defining symptom, and the implications of exercise recommendations.

As @A.B. said above, VO2max didn't drop, just max workload and heart rate at maximal exertion. It seems like objectively determined maximal exertion was reached, with an actual Respiratory Exchange Rate (RER) showing exhaustion of aerobic energy production. So the lower max workload wasn't due to slacking off:

ETA: Note that the MS patients are 20 years older than the CFS patients. So they're not necessarily in worse shape, and values can't be directly compared between those two groups.

similar been done before, they could try measuring relevant by-products / metabolites after 30 minutes of exercise or try using a high grade thermal camera to look at heat generation / distribution / circulation etc

Replication is really essential for the two-day CPET. Yes, it's been done before but it's always in small numbers due to the expense. And it's really great to have different teams replicating independently of each other - it makes it so much harder for the psychosocial quacks to dismiss the evidence when it's coming from 4 or 5 different countries.

I'd also point out that this is explicitly a pilot study. Hopefully we'll be seeing something bigger and more elaborate in the future from them

 

[John Mac]

There was a press release about this study a couple of months ago.
Discussed here:
http://forums.phoenixrising.me/index.php?threads/distinguishing-cfs-new-zealand-research.51357/

"To find out more, Dr Hodges is completing another trial examining the physiological differences in repeated maximal exercise at 48 hours and 72 hours. “We will be taking blood samples to examine markers of inflammation, blood pressure and heart rate, asking questions about fatigue, and participants will be asked to do simple computer tasks to examine cognition, as well as ultrasound to measure arterial stiffness, and the cycle test to examine anaerobic threshold. All tests will then be repeated at either 48 hours or 72 hours later.”

 

[Londinium]

No, no, please tell me more about how it's all deconditioning...

This study is contradictory to research to date, which has suggested that a single maximal exercise test is enough to observe differences between CFS/ME and CFS HC. This study has shown that by performing a single maximal exercise test, there are no significant differences between healthy controls and CFS/ME. In the current exercise study, patients with CFS/ME were of moderate fitness

 

[*GG*]

Here are my results from 2010.

GG

 

[JaimeS]

All CFS/ME participants completed the De Paul Symptom and SF-36 screening questionnaire. CFS/ME participants were included if they met all three case definitions: Fukuda case definition (Fukuda et al., 1994), the Canadian Consensus Criteria (2003) and the International Consensus Criteria (2011).

Well done, pilot study. Now, aim for more people!

 

[daisybell]

There was a press release about this study a couple of months ago.
Discussed here:
http://forums.phoenixrising.me/index.php?threads/distinguishing-cfs-new-zealand-research.51357/

"To find out more, Dr Hodges is completing another trial examining the physiological differences in repeated maximal exercise at 48 hours and 72 hours. “We will be taking blood samples to examine markers of inflammation, blood pressure and heart rate, asking questions about fatigue, and participants will be asked to do simple computer tasks to examine cognition, as well as ultrasound to measure arterial stiffness, and the cycle test to examine anaerobic threshold. All tests will then be repeated at either 48 hours or 72 hours later.”

I don't know how many people actually had blood taken - I was a participant in this trial and didn't get blood drawn...

 

[Denise]

I'd be interested to know what form of MS the participants had and whether that made a difference in their test results.

 

[Snow Leopard]

I believe that the reason why patients were able to reproduce their VO2Peak because they didn't exercise to VO2Max. This is also the reason why the healthy controls were able to increase their VO2Peak, because they didn't reach VO2Max either. VO2Max will occur much higher than 150-160bpm in people with an average age of 37, it occurs well past the ventilatory/anaerobic threshold. The lower performance of the MS group is also likely to be due to the much higher average age (55).

This is why we are seeing some variance between studies...

Here are the (cited) age norms for fitness from Heyward & Gibson:

My own experience of the 2 Day test is that it is VERY HARD and leads to more severe symptoms for weeks. My performance was "good" on the first day and borderline "fair-poor" on the second day according to the table.

Also, why are no RER values provided?

 

[Snow Leopard]

Beyond the timing of the protocol, within the literature, many have questioned the use of a maximal exercise test for CFS/ME individuals with reference to ethics, due to the negative health effects associated with maximal exertion (Snell et al., 2013). The results of the current study suggest that a maximal fitness test may not be required to test those with CFS/ME and instead a test up until anaerobic threshold may be sufficient. Anaerobic threshold may be enough to elicit the most notable abnormal responses. Anaerobic data demonstrated reductions in heart rate, work and a low efficiency of oxygen utilization which may limit exercise tolerance. It is important to find out what physiological mechanisms are responsible for the exercise intolerance. Muscular work is a complex interaction of diverse physiological mechanisms designed to ensure that oxygen delivery meets oxygen demands. The heart, lung and oxygen carrying capacity of the blood participate in these adjustments.

This explains the difference in protocol (eg exercising only to the ventilatory threshold) experienced by people in the participating in the follow up study:
http://forums.phoenixrising.me/index.php?threads/distinguishing-cfs-new-zealand-research.51357/

But as I mentioned above, I suspect that patients didn't achieve true VO2Max in this study either.

 

[Valentijn]

Also, why are no RER values provided?

I'm a little suspicious of that too. But it wouldn't be a VO2max without sufficient RER, and they are calling it a VO2max.

 

[slysaint]

I'm a little suspicious of that too. But it wouldn't be a VO2max without sufficient RER, and they are calling it a VO2max.

according to wikipedia:
"many protocols for estimating VO2 max have been developed for those for whom a traditional VO2 max test would be too risky. These generally are similar to a VO2 max test, but do not reach the maximum of the respiratory and cardiovascular systems and are called sub-maximal tests."
could this be what they're using?

 

[Valentijn]

could this be what they're using?

No, because if it was submaximal, it wouldn't be maximal They say it's maximal.

 

[Snow Leopard]

I'm a little suspicious of that too. But it wouldn't be a VO2max without sufficient RER, and they are calling it a VO2max.

Maximal exertion occurs at maximum heart rate, well past the anaerobic threshold. A mean heart rate of 153 is far from the mean heart rate of ~37 year old women.

 

[Dolphin]

The results of the current study suggest that a maximal fitness test may not be required to test those with CFS/ME and instead a test up until anaerobic threshold may be sufficient. Anaerobic threshold may be enough to elicit the most notable abnormal responses.

 

[JaimeS]

My own experience of the 2 Day test is that it is VERY HARD and leads to more severe symptoms for weeks. My performance was "good" on the first day and borderline "fair-poor" on the second day according to the table.

Very well-spotted re: why we don't always see the same results!