Twee presentaties op de internationale IACFS-ME-konferentie in Ottawa
bevestigen wat veel ME/CVS-patiėnten al lang weten:
- Een inspanning wordt duur betaald (studie 1)!
(Veel) patiėnten presteren aanzienlijk minder bij een tweede fietstest 24 uur later.
De verzuringsdrempel,
de inspanning waarbij lichaam over moet schakelen naar anareobe energieproduktie,
(vaak) met melkzuurproductie tot gevolg, en
de inspanning die men kan leveren "zonder te verzuren" nemen met ca. 20% af.
- Patiėnten kunnen hun (relatieve) inspanningen goed inschatten (studie 2).
Veel patiėnten halen hun maximale hartslag bij lange na niet,
waarschijnlijk omdat de arm- en beenspieren voor die tijd al verzuren,
en toch leveren ze verhoudingsgewijs een "enorme" inspanning
De hartslag weerspiegelt (correleert met) de inschatting van de inspanning:
De zuurstofopname bij "de verzuringsdrempel" is de tweede dag zo laag
dat gewone dagelijkse bezigheden als tot anaerobe energieproduktie leiden...
Hierbij moeten worden opgemerkt dat het aantal deelnemers relatief beperkt was,
maar de eerste konklusie, inspanning pakt negatief uit, is reeds eerder aangetoond
(klik hier en hier).
Voor de syllabus met samenvattingen van alle lezingen, klik op onderstaande afbeelding:
(laden duurt lang, FT)
Exercise testing to quantify effects of fatigue on functional capacity
in patients with CFS.
Keller BA, Micale FG.
IACFS-ME 2011 Conference Syllabus
http://www.iacfsme.org/LinkClick.aspx?fileticket=EFIrm%2buCnkM%3d&tabid=142
Objective:
The purpose of this study was to assess
the effects of post-exertional malaise (PEM) on
functional capacity and anaerobic threshold
in subjects diagnosed with chronic fatigue syndrome (CFS).
Methods:
Subjects were
10 females and 2 males (41.3+1.11 yrs) diagnosed with CFS
by a physician experienced in the diagnosis of CFS.
To induce PEM, each subject completed a maximum exercise test on a cycle ergometer.
A second maximum exercise test was performed 24 hrs later
to assess the effects of exercise-induced PEM on functional capacity.
Maximum oxygen consumption (VO2max), maximum heart rate (HRmax),
anaerobic threshold (AT), maximum workload (Wmax),
workload at AT (ATwork), and respiratory exchange ratio (RER)
were measured.
RER is an objective indicator of
substrate utilization and subject effort during exercise.
Results:
Significant decreases
from test 1 to test 2 were
13.5% for VO2max (21.5 to 18.6 ml.kg-1.min-1; p<0.01),
8 bpm for HRmax (p<0.01),
18.8% for AT (12.0 to 9.7 ml.kg-1.min-1; p<0.05),
9.4% for Wmax (121 to 109 W, p<0.05), and
17.3% for ATwork (58.3 to 48.2 W; p<0.05).
However, there was no change in maximum RER
indicating that subject effort was maximum and also comparable during both tests.
Conclusion:
Results indicate that
PEM decreased maximum functional capacity by more than 13% to below 5 METS;
a level at or below that which is required by many job-related activities and IADLs.
To compare,
VO2max in healthy individuals is highly reproducible
over days and even months (r>.95), with a SEM of < 6%.
Thus, for subjects in this study,
an expected variation between tests would be ±1.29 ml.kg-1.min-1
in contrast to the observed decrease of 2.9 ml.kg-1.min-1.
Furthermore,
PEM decreased AT to below 3 METS
(e.g., light-moderate speed walking),
which is a level of many activities considered to be sedentary in nature.
Thus,
completion of sedentary ADLs and IADLs for those with CFS
requires production of energy via anaerobic processes
that will further contribute to PEM and exacerbate symptoms of CFS.
Since many daily activities fall into the 3-5 MET range,
individuals with CFS will exacerbate symptoms associated with PEM
simply by completing normal daily activities.
Afkortingen [FT]
ADLs: Activities of daily living (ADLs) activiteiten van het dagelijks leven (verzorging).
IADLs: Instrumental activities of daily living, dingen die men dagelijks moet doen
om zelfstandig te kunnen leven (zoals eten maken, boodschappen doen, reizen en huishouding).
SEM: standaardfout, de te verwachten boven- en ondergrens (klik hier)
Effort perception in chronic fatigue syndrome is not impaired.
Benjamin M. Larson, Davenport TE, Stevens SR, Stevens J, Van Ness JM, Snell CR.
http://www.iacfsme.org/LinkClick.aspx?fileticket=EFIrm%2buCnkM%3d&tabid=142
Background and Objectives:
Activity pacing is one cornerstone of rehabilitation management for CFS.
Optimal criteria for pacing are currently unclear, because
patients with CFS may have an impaired ability to self-assess their level of physical exertion.
However, this hypothesis has yet to be directly tested.
The purpose of this study was to determine
the association between subjective and objective indicators of physical effort
in patients with CFS and matched controls.
Materials and Methods:
Sixteen patients with CFS and 14 age- and sex-matched non-disabled, sedentary individuals
were tested.
Each subject received
2 maximal cardiopulmonary exercise tests (CPETs) on a braked bicycle ergometer
that were administered 24 hours apart.
Heart rate (HR) was measured continuously and
rating of perceived exertion (RPE) was assessed at each minute
from rest and unloaded cycling until peak exercise.
Descriptive statistics (mean ± standard deviation)
were calculated for all dependent variables (DVs),
including peak HR (HRpeak), HR at VT (HRVT), peak RPE (RPEpeak) and RPE at VT (RPEVT).
2x2 analysis of variance (ANOVA) was used to assess
the main and interaction effects of group and test on DV measurements.
Repeated measures ANOVA was used to assess
group and time main and interaction effects on DV measurements.
Pearsons correlations (r) were calculated
to determine the within-groups associations between HR and RPE during each CPET.
Criterion for statistical significance of differences was
Results:
All subjects met standard criteria for maximal effort during each CPET.
HRpeak was significantly lower
for patients with CFS (CPET1: 158±15 beats per minute [bpm]; CPET2: 156±17bpm)
compared to controls (CPET1: 182±13bpm; CPET2: 183±11bpm)
on both CPETs (p<.01).
HRVT also was significantly lower
for patients with CFS (CPET1: 113±21bpm; CPET2: 111±14bpm)
compared to controls (CPET1: 122±15bpm; CPET2: 131±17bpm)
on both CPETs (p<.01).
RPEpeak was significantly greater
in patients with CFS (CPET1: 19.4±1.0; CPET2: 19.6±0.07)
compared to controls (CPET1: 19.4±0.8; CPET2: 18.7±2.1)
on both CPETs (p<.01).
RPEVT also was significantly greater
in patients with CFS (CPET1: 13.2±2.5; CPET2: 12.7±2.6)
compared to controls (CPET1: 10.2±2.5; CPET2: 11.2±2.4)
on both CPETs (p<.01).
Time series analysis revealed significant group effects for HR (p<.01) and
significant group and group x time effects for RPE (p<.01).
HR and RPE demonstrated moderate to high correlation in subjects with CFS
(CPET1: r=.769, r2=.591; p<.001; CPET2: r=.765, r2=.591; p<.001) and
control subjects (CPET1: r=.742, r2=.551; p<.001; CPET2: r=.688, r2=.473; p<.001).
Conclusion:
Subjects with CFS demonstrated significantly greater effort ratings
than control subjects during each CPET.
HR and RPE were significantly correlated
in subjects with CFS and matched control subjects.
Clinical Relevance:
The significant association between HR and RPE indicates
patients with CFS can accurately perceive their level of physical exertion.
Thus,
patients perceptions of physical exertion can be used with confidence
as a basis for pacing self-management programs.
Afkortingen [FT]
VT: Ventilatory Threshold (berekende schatting van de verzuringsdrempel/aerobic treshold).
Met dank aan Rob, die me attendeerde op de syllabus met samenvattingen.
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