Tag: aerobic work capacity

Aerobic capacity of Gulf War veterans with chronic fatigue syndrome

Abstract:

A large overlap exists between the diagnosis of chronic fatigue syndrome (CFS) and the unexplained symptoms reported by many Gulf War veterans (GV). Previous investigations have reported reduced aerobic capacity in civilians with CFS. The present investigation examined metabolic responses to maximal exercise in GVs with CFS compared with healthy GVs.

Cardiorespiratory and metabolic responses were recorded during a maximal exercise test on a cycle ergometer. The groups were not different in any demographic category (p > 0.05) or self-reported physical activity (p > 0.05). No differences were observed between groups for maximal oxygen uptake (28.9 +/- 6.7 mL/kg/min for CFS vs. 30.8 +/- 7.1 mL/kg/min for controls; p = 0.39), heart rate (155.8 +/- 16.1 bpm for CFS vs. 163.3 +/- 14.9 bpm for controls; p = 0.17), exercise time (9.6 +/- 1.5 minutes for CFS vs. 10.2 +/- 1.4 minutes for controls; p = 0.26), or workload achieved (208 +/- 36.7 W for CFS vs. 224 +/- 42.9 W for controls; p = 0.25). Likewise, no differences were observed at submaximal intensities (p > 0.05).

Compared with healthy controls, GVs who report multiple medically unexplained symptoms and meet criteria for CFS do not show a decreased exercise capacity. Thus, it does not appear that the pathology of the GVs with CFS includes a deficiency with mobilizing the cardiopulmonary system for strenuous physical effort.

 

Source: Nagelkirk PR, Cook DB, Peckerman A, Kesil W, Sakowski T, Natelson BH, LaManca JJ. Aerobic capacity of Gulf War veterans with chronic fatigue syndrome. Mil Med. 2003 Sep;168(9):750-5. http://www.ncbi.nlm.nih.gov/pubmed/14529252

 

Metabolic and cardiovascular effects of a progressive exercise test in patients with chronic fatigue syndrome

Abstract:

PURPOSE: To evaluate the aerobic power (as maximum volume of oxygen consumed [VO2 max]) of women with chronic fatigue syndrome (CFS).

PATIENTS AND METHODS: Twenty-one women with CFS and 22 sedentary healthy controls (CON) were studied at the CFS Cooperative Research Center Exercise Laboratory at the VA Medical Center, East Orange, New Jersey. Performance was measured on an incremental treadmill protocol walking to exhaustion. Expired gases were analyzed by a metabolic system, heart rate was recorded continuously, and ratings of perceived exertion (RPE) were taken at each workload. The groups were divided into those who achieved VO2 max (CFS-MAX and CON-MAX) and those who stopped at a submaximal level (CFS-NOMAX and CON-NOMAX) by using standard criteria.

RESULTS: Seventeen CON and 10 CFS subjects achieved VO2 max. The VO2 max (mL/kg/min) of the CFS-MAX (28.1 +/- 5.1) was lower than that of the CON-MAX (32.1 +/- 4.3, P = 0.05). The CFS-MAX achieved 98 +/- 11% of predicted VO2 max. The CFS group had a higher RPE at the same absolute workloads as controls (P < 0.01) but not the same relative workloads.

CONCLUSION: Compared with normal controls, women with CFS have an aerobic power indicating a low normal fitness level with no indication of cardiopulmonary abnormality. Our CFS group could withstand a maximal treadmill exercise test without a major exacerbation in either fatigue or other symptoms of their illness.

Comment in:

Exercise limits in chronic fatigue syndrome. [Am J Med. 1997]

Graded exercise testing and chronic fatigue syndrome. [Am J Med. 1997]

 

Source: Sisto SA, LaManca J, Cordero DL, Bergen MT, Ellis SP, Drastal S, Boda WL, Tapp WN, Natelson BH. Metabolic and cardiovascular effects of a progressive exercise test in patients with chronic fatigue syndrome. Am J Med. 1996 Jun;100(6):634-40. http://www.ncbi.nlm.nih.gov/pubmed/8678084

 

Exercise responses and psychiatric disorder in chronic fatigue syndrome

Comment in: Exercise responses in the chronic fatigue syndrome. Objective assessment of study is difficult without knowledge of data. [BMJ. 1995]

 

Fatigue, exercise intolerance, and myalgia are cardinal symptoms of the chronic fatigue syndrome, but whether they reflect neuromuscular dysfunction or are a manifestation of depression or other psychiatric or psychological disorders diagnosed in a high proportion of fatigued patients in the community is unclear.’ In previous studies patients with the chronic fatigue syndrome showed exercise intolerance in incremental exercise tests, which seemed to be related to an increased perception of effort; also, blood lactate concentrations in some patients tended to increase more rapidly than normal at low work rates, implying inefficient aerobic muscle metabolism.2 We examined venous blood lactate responses to exercise at a work rate below the anaerobic threshold in relation to psychiatric disorder.

You can read the rest of this article here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2550606/pdf/bmj00607-0028.pdf

 

Source: Lane RJ, Burgess AP, Flint J, Riccio M, Archard LC. Exercise responses and psychiatric disorder in chronic fatigue syndrome. BMJ. 1995 Aug 26;311(7004):544-5. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2550606/pdf/bmj00607-0028.pdf

 

Pharmacological approaches to the therapy of chronic fatigue syndrome

Abstract:

Although a variety of pharmacological agents have been used to treat patients with chronic fatigue syndrome none has been shown to effect a complete resolution of symptoms.

Data obtained from a retrospective study and from an objective assessment of the aerobic work capacity of patients with this disorder suggest that the underlying pathophysiological abnormality is a disorder of sleep regulation. This results not only in profound fatigue and lethargy but also reduced sensory threshold for pain, disordered temperature regulation, cardiovascular abnormalities, disturbed higher cerebral function and mental depression.

Drugs which modulate sleep, such as tricyclic antidepressants, have a limited effect in improving the symptoms that CFS patients experience. We suggest that other agents which affect central nervous system neurotransmitters, particularly serotonin, may have potential in the management of this condition and need to be evaluated in large controlled clinical trials.

 

Source: McCluskey DR. Pharmacological approaches to the therapy of chronic fatigue syndrome. Ciba Found Symp. 1993;173:280-7; discussion 287-97. http://www.ncbi.nlm.nih.gov/pubmed/8491103

 

Chronic fatigue syndrome

Abstract:

Chronic Fatigue Syndrome appears to represent a spectrum of disorders in which a variety of pathophysiological mechanisms may operate. While the initiating event in the majority of patients is a pyrexial illness, possibly due to enterovirus infection, evidence of persisting infection or inflammatory changes in muscle and/or brain remain unconvincing.

CFS patients display a definite reduced aerobic work capacity compared to normal control subjects, but this may reflect a state of deconditioning resulting from prolonged physical inactivity. They also have an altered perception of their level of exertion and premorbid fitness.

The characteristic fluctuation in symptoms, with periods of relapses and partial remissions, may indicate that some central disorder of sensory perception is operational. It may be that a primary sleep disorder results in a reduced sensory threshold for afferent stimuli from muscle. This could well account for many of the subjective symptoms which patients experience. Much more research is clearly necessary if we are to achieve a better understanding of this distressing and at present enigmatic disorder.

 

Source: McCluskey DR, Riley MS. Chronic fatigue syndrome. Compr Ther. 1992 Apr;18(4):13-6. http://www.ncbi.nlm.nih.gov/pubmed/1628478

 

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/