Category: Exercise

Aerobic work capacity in chronic fatigue syndrome

Comment on Aerobic work capacity in patients with chronic fatigue syndrome. [BMJ. 1990]

SIR,

The data of Dr Marshall S Riley and colleagues (1) are consistent with our findings (2) that most patients referred with the chronic fatigue syndrome have the effort syndrome-that is, chronic hyperventilation as a consequence of excessive effort and distress.(3)

May we draw attention to three points. Dr Riley and colleagues concluded that the patients could not be hyperventilating because their values of end-tidal partial pressure of carbon dioxide at rest and at peak exercise did not differ significantly from those of the controls.

In our opinion the values published for the controls (35 8 mmHg at rest and 36-3 mmHg at peak exercise) are too low to be accepted as normal. The finding that the patients reached their anaerobic threshold far quicker than did the controls is consistent with the early acidosis on exertion known to occur in chronic hyperventilation. This is a consequence of the depletion of the body’s buffer base reserves,(4) brought about by renal compensation for chronic respiratory alkalosis.(5)

You can read the rest of this comment here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1664329/pdf/bmj00207-0055b.pdf

 

Source: Rosen SD, King JC, Wilkinson JB, Nixon PG. Aerobic work capacity in chronic fatigue syndrome. BMJ. 1990 Nov 24;301(6762):1217. [Comment] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1664329/

 

Aerobic work capacity in patients with chronic fatigue syndrome

Abstract:

OBJECTIVE: To determine the aerobic work capacity of patients with the chronic fatigue syndrome and compare it with that of two control groups, and to assess the patients’ perception of their level of activity before and during illness.

DESIGN: A symptom limited exercise treadmill test with on line gas analysis and blood sampling was used. Subjects were assessed by one investigator, who was blind to the group which they were in.

SETTING: Department of medicine, Royal Victoria Hospital, Belfast.

SUBJECTS: 13 Patients (10 women, three men) who fulfilled the diagnostic criteria for chronic fatigue syndrome. Two control groups of similar age, sex, and body weight: 13 normal subjects (10 women, three men) and seven patients (five women, two men) with the irritable bowel syndrome.

MAIN OUTCOME MEASURES: Aerobic work capacity as assessed by several variables such as length of time on treadmill, heart rate, and biochemical measurements; Borg score; and visual analogue scores of perceived level of physical activity.

RESULTS: The patients with the chronic fatigue syndrome had a reduced exercise capacity compared with that of the other subjects, spending a significantly shorter time on the treadmill. They had a significantly higher heart rate at submaximal levels of exertion and at stage III exertion had significantly higher blood lactate concentrations. Using a Borg score, they showed a significantly altered perception of their degree of physical exertion with a mean score of 8.2 compared with 6.6 and 5.3 for the normal subjects and patients with the irritable bowel syndrome respectively. Using a visual analogue scale they indicated that they had a greater capacity for activity before illness than had the patients with the irritable bowel syndrome, but the scores were not significantly different between the two groups. Both groups of patients indicated reduced activity at the time of testing. Normal controls and patients with the irritable bowel syndrome aspired to a greater level of activity than their current level, but the patients with the chronic fatigue syndrome aspired to a level similar to that which they had had before their illness.

CONCLUSIONS: Patients with the chronic fatigue syndrome have reduced aerobic work capacity compared with normal subjects and patients with the irritable bowel syndrome. They also have an altered perception of their degree of exertion and their premorbid level of physical activity.

 

Source: Riley MS, O’Brien CJ, McCluskey DR, Bell NP, Nicholls DP. Aerobic work capacity in patients with chronic fatigue syndrome. BMJ. 1990 Oct 27;301(6758):953-6. http://www.ncbi.nlm.nih.gov/pubmed/2249024

Note: You can read the full article here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1664147/

 

Patient management of post-viral fatigue syndrome

Abstract:

A case definition for post-viral fatigue syndrome is proposed within which various subgroups of patients exist. Any one treatment may not apply to all the subgroups. In particular, patients’ experiences do not show that avoidance of exercise is maladaptive. It is proposed that the recently ill often try to exercise to fitness whereas the chronically ill have learnt to avoid exercise. Recovery is more likely to be achieved if patients learn about their illness and do not exhaust their available energy.

 

Source: Ho-Yen DO. Patient management of post-viral fatigue syndrome. Br J Gen Pract. 1990 Jan;40(330):37-9. http://www.ncbi.nlm.nih.gov/pubmed/2107839

Note: You may read the full article here:  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1371214/

 

Cardiac function at rest and with exercise in the chronic fatigue syndrome

Abstract:

To evaluate a possible cardiac pathophysiology of the chronic fatigue syndrome, we compared the resting cardiac function and exercise performance of 41 patients to those of an age-matched and sex-matched normal control group.

Persistent fatigue following an acute apparently viral illness was the major complaint of all patients; none had specific cardiac symptoms nor abnormal physical findings. Electrocardiographic spatial patterns were normal in the patients, and there were no differences in the body surface sum of positive T-wave integrals between the patients (240 microV.x 10(2) +/- 107 microV.s x10(2)) and control (244 microV.x 10(2) +/- 108 microV.s x 10(2) subjects. Twenty-four hour ambulatory ECGs revealed no differences in sinus rates and incidences of ventricular dysrhythmias in the two populations. Left ventricular dimensions and systolic fractional shortening values were also similar in both groups; moreover none of the patients had segmental wall motion abnormalities.

On graded exercise testing, 20 of 32 normal subjects achieved target (85 percent of age-maximum) heart rates, compared to four of 31 patients (p less than 0.001). The duration of exercise averaged 12 +/- 4 minutes for the normal subjects and 9+/- 4 minutes for the patients (p less than 0.01). The temporal profile of exercise heart rates was dissimilar in the two groups, with patients’ rates consistently and progressively less than those of normal subjects. Peak heart rate averaged 152 +/- 16 beats per minute for the normal group vs 124 +/- 19 beats per minute for the patients (p less than 0.0001); in age-related terms, respectively, 82 +/- 6 percent of the maximum heart rate vs 66 +/- 10 percent (p less than 0.0001).

Thus, patients with chronic fatigue syndrome have normal resting cardiac function but a markedly abbreviated exercise capacity characterized by slow acceleration of heart rate and fatigue of exercising muscles long before peak heart rate is achieved.

(ABSTRACT TRUNCATED AT 250 WORDS)

 

Source: Montague TJ, Marrie TJ, Klassen GA, Bewick DJ, Horacek BM. Cardiac function at rest and with exercise in the chronic fatigue syndrome. Chest. 1989 Apr;95(4):779-84. http://www.ncbi.nlm.nih.gov/pubmed/2924607