"persistent fatigue may be ... result of individual reaching or exceeding their lactate threshold"

[Dolphin]

I can't see the full text of this. But I happened to see this bit, which I thought was interesting to see explicitly written:

... We hypothesize that persistent fatigue may be the result of an individual reaching

or exceeding their lactate threshold during their activities of daily living, as has been
suggested for individuals with chronic fatigue syndrome [32]. ...

I'm not particularly excited by their interpretation i.e. just because there is higher lactate levels, doesn't mean it can easily be treated with exercise:

Cardiorespiratory and neuromuscular deconditioning in fatigued and non-fatigued breast cancer survivors

Sarah E. Neil, Riggs J. Klika, S. Jayne Garland, Donald C. McKenzie and Kristin L. Campbell

Supportive Care in Cancer 2012, DOI: 10.1007/s00520-012-1600-yOnline First™

Abstract

Purpose
Fatigue is one of the most commonly reported side effects during treatment for breast cancer and can persist following treatment completion. Cancer-related fatigue after treatment is multifactorial in nature, and one hypothesized mechanism is cardiorespiratory and neuromuscular deconditioning. The purpose of this study was to compare cardiorespiratory and neuromuscular function in breast cancer survivors who had completed treatment and met the specified criteria for cancer-related fatigue and a control group of breast cancer survivors without fatigue.

Methods
Participants in the fatigue (n = 16) and control group (n = 11) performed a maximal exercise test on a cycle ergometer for determination of peak power, power at lactate threshold, and VO2 peak. Neuromuscular fatigue was induced with a sustained submaximal contraction of the right quadriceps. Central fatigue (failure of voluntary activation) was evaluated using twitch interpolation, and peripheral fatigue was measured with an electrically evoked twitch.

Results
Power at lactate threshold was lower in the fatigue group (p = 0.05). There were no differences between groups for power at lactate threshold as percentage of peak power (p = 0.10) or absolute or relative VO2 peak (p = 0.08 and 0.33, respectively). When adjusted for age, the fatigue group had a lower power at lactate threshold (p = 0.02) and absolute VO2 peak (p = 0.03). There were no differences between groups in change in any neuromuscular parameters after the muscle-fatiguing protocol.

Conclusions
Findings support the hypothesis that cardiorespiratory deconditioning may play a role in the development and persistence of cancer-related fatigue following treatment. Future research into the use of exercise training to reduce cardiorespiratory deconditioning as a treatment for cancer-related fatigue is warranted to confirm these preliminary findings.

Keywords Cancer – Fatigue – Physical activity – Deconditioning – Muscle

 

[Snow Leopard]

I think the lower threshold is associated with fatigue, but is not the cause of the sensation of fatigue. Nor will muscular conditioning improve the fatigue (though it may improve the lactate threshold).

 

[alex3619]

A key point in ME, though needing more research even now, is that many of us have critical lowering of lactate threshold as a result of PEM/PENE. This is a hallmark of ME I suspect. So if we exercise too much, then we damage our lactate threshold, we dont increase it. This is why Pacific Fatigue Labs emphasizes anaerobic conditioning in ME/CFS. We need more exercise physiologists to grapple with this.

Lactate does not in itself cause major problems in the short term, though it can if prolonged (e.g. lactic acidosis which can be fatal). Its more a sign that there is a switch in metabolism, and many many factors occur in that switch.

Bye, Alex

 

[Mark]

I recently met someone who told me she was now pretty much recovered from a fibromyalgia diagnosis. I asked her for some details, and what jumped out for me was that she had also had a diagnosed lactic acidosis problem, related to pain in one leg following an accident (I didn't get all the details on that so may have misunderstood that slightly perhaps). The leg problem was eventually dealt with, just before the remission of fibromyalgia symptoms (I can't recall how, I think she described something like physio which had 'unblocked' something in her hip). She didn't attribute her recovery from FM to the treatment of the problem with her leg (though that seemed quite likely to me and she admitted that explanation fitted well in terms of her time of onset and remission), but the take-home for me was that it seemed likely to me that lactic acidosis was the underlying cause of her fibro diagnosis. I guess that lactic acidosis can also be one of many downstream effects rather than an underlying cause as it seemed to be in this case, and many of the symptoms would be similar in both situations.