peak oxygen consumption – Page 2 – American ME and CFS Society

Maximal handgrip strength can predict maximal physical performance in patients with chronic fatigue

Abstract:

BACKGROUND: Maximal handgrip strength is used to predict exercise performance in healthy older subjects and in patients with chronic obstructive pulmonary disease, breast cancer or cirrhosis. Our objective was to evaluate the ability of maximal handgrip strength to predict maximal exercise performance in patients with chronic fatigue.

METHODS: Sixty-six patients with myalgic encephalomyelitis/chronic fatigue syndrome and 32 patients with chronic fatigue but no diagnosis of myalgic encephalomyelitis/chronic fatigue syndrome were included. The maximal physical performance was measured on a cycle ergometer to measure the peak oxygen uptake and the maximal work rate. We searched for linear regressions between maximal handgrip strength and maximal performances.

FINDINGS: No significant differences in slopes and ordinates of regression lines were noted between patients with or without a diagnosis of myalgic encephalomyelitis/chronic fatigue syndrome, allowing to pool the data. Maximal handgrip strength was significantly and positively correlated with peak oxygen uptake and maximal work rate in all patients with chronic fatigue.

INTERPRETATION: We conclude that handgrip strength can predict maximal exercise performance in patients with chronic fatigue.

Source: Jammes Y, Stavris C, Charpin C, Rebaudet S, Lagrange G, Retornaz F. Maximal handgrip strength can predict maximal physical performance in patients with chronic fatigue. Clin Biomech (Bristol, Avon). 2020 Jan 9;73:162-165. doi: 10.1016/j.clinbiomech.2020.01.003. [Epub ahead of print] https://www.ncbi.nlm.nih.gov/pubmed/31986462

Exercise tolerance testing in a prospective cohort of adolescents with chronic fatigue syndrome and recovered controls following infectious mononucleosis

Abstract:

OBJECTIVE: Six months after acute infectious mononucleosis (IM), 13% of adolescents meet criteria for chronic fatigue syndrome (CFS). We measured exercise tolerance in adolescents with CFS and control subjects 6 months after IM.

STUDY DESIGN: Twenty-one adolescents with CFS 6 months after IM and 21 recovered control subjects performed a maximal incremental exercise tolerance test with breath-by-breath gas analysis. Values expressed are mean+/-standard deviation.

RESULTS: The adolescents diagnosed with CFS and control subjects did not differ in age, weight, body mass index, or peak work capacity. Lower oxygen consumption peak percent of predicted was seen in adolescents with CFS compared with control subjects (CFS 99.3+/-16.6 vs control subject 110.7+/-19.9, P=.05). Peak oxygen pulse also was lower in adolescents with CFS compared with recovered control subjects (CFS 12.4+/-2.9 vs control subjects 14.9+/-4.3, P=.03).

CONCLUSIONS: Adolescents with CFS 6 months after IM have a lower degree of fitness and efficiency of exercise than recovered adolescents. Whether these abnormal exercise findings are a cause or effect of CFS is unknown. IM can lead to both fatigue and measurable changes in exercise testing in a subset of adolescents.

Source: Katz BZ, Boas S, Shiraishi Y, Mears CJ, Taylor R. Exercise tolerance testing in a prospective cohort of adolescents with chronic fatigue syndrome and recovered controls following infectious mononucleosis. J Pediatr. 2010 Sep;157(3):468-72, 472.e1. doi: 10.1016/j.jpeds.2010.03.025. Epub 2010 May 6. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2975670/ (Full article)

Comparison of two exercise testing protocols in patients with chronic fatigue syndrome

Abstract:

This study examined whether a linear exercise stress-testing protocol generated different peak exercise performance variables than a stepwise exercise testing protocol in patients with chronic fatigue syndrome (CFS). We conducted a comparative study with patients randomly allocated to one of two exercise testing protocols.

Twenty-eight women with CFS completed two self-reported measures (the CFS Symptom List and the CFS Activities and Participation Questionnaire) and then performed until exhaustion either the linear or the stepwise exercise testing protocol with continuous monitoring of physiological variables (heart rate and oxygen uptake).

At baseline, we found no significant differences in demographic features and health status between groups (p > 0.05). Based on ratio peak workload/peak oxygen uptake, mechanical efficiency was lower among the subjects performing the stepwise protocol (p = 0.002). When we analyzed the mean linear regression slope values between oxygen uptake and workload from each subject’s minute-by-minute exercise data points, we found that mechanical efficiency was lower among the subjects performing the stepwise protocol (p = 0.039). Apart from mechanical efficiency, we found no differences in exercise performance data between groups (p > 0.05).

Our results suggest that the difference between linear and stepwise exercise protocols cannot account for all discrepancies of previous studies on exercise performance data in women with CFS, but they do suggest that the nature of the exercise testing protocol influences mechanical efficiency in these patients. Further study is warranted.

Source: Nijs J, Zwinnen K, Meeusen R, de Geus B, De Meirleir K. Comparison of two exercise testing protocols in patients with chronic fatigue syndrome. J Rehabil Res Dev. 2007;44(4):553-9. http://www.rehab.research.va.gov/jour/07/44/4/Nijs.html (Full article)

Exercise testing in children and adolescents with chronic fatigue syndrome

Abstract:

The objective of this study was to evaluate exercise capacity in children and adolescents diagnosed with Chronic Fatigue Syndrome (CFS). We examined 20 patients (12 girls and 8 boys; mean age 14.9 +/- 3.7 years) diagnosed with CFS.

Exercise capacity was measured using a maximal exercise test on a bicycle ergometer and an expired gas analysis system. Fatigue was assessed using a questionnaire and a daily activity diary was used to describe activities for three days. Z-scores were calculated using age- and sex-matched reference values. Z-scores in children and adolescents with CFS were – 0.33 +/- 1.0 (p = 0.17) for peak oxygen uptake, – 1.13 +/- 1.41 (p = 0.002) for relative peak oxygen uptake [ml/kg/min] and – 0.93 +/- 1.29 (p = 0.07) for maximal work load. Both heart rate and blood pressure at peak performance were significantly reduced compared to reference values.

Fatigue levels were significantly positively associated with age and negatively with blood pressure at peak exercise (p < 0.05). In conclusion maximum exercise testing was feasible in young people with CFS. Maximal exercise capacity was only reduced in a minority of the patients and was related to current physical activity levels.

Source: Takken T, Henneken T, van de Putte E, Helders P, Engelbert R. Exercise testing in children and adolescents with chronic fatigue syndrome. Int J Sports Med. 2007 Jul;28(7):580-4. Epub 2007 Mar 15. https://www.ncbi.nlm.nih.gov/pubmed/17357961

Chronic fatigue syndrome: new evidence for a central fatigue disorder

Abstract:

Considerable evidence points towards a prominent role for central nervous system (CNS) mechanisms in the pathogenesis of chronic fatigue syndrome (CFS), a disorder characterized chiefly by persistent, often debilitating, fatigue. We wished to characterize circulating profiles of putative amino acid modulators of CNS 5-hydroxytryptamine (5-HT; serotoninergic) and dopaminergic function in CFS patients at rest, as well as during symptom-limited exercise and subsequent recovery.

Groups of 12 CFS patients and 11 age- and sex-matched sedentary controls, with similar physical activity histories, underwent ramp-incremental exercise to the limit of tolerance. Plasma amino acid concentrations, oxygen uptake and ratings of perceived exertion were measured at rest, and during exercise and recovery.

Peak oxygen uptake was significantly lower in the CFS patients compared with controls. Rating of perceived exertion in the patients was higher at all time points measured, including at rest, relative to controls. Levels of free tryptophan (free Trp), the rate-limiting 5-HT precursor, were significantly higher in CFS patients at exhaustion and during recovery, whereas concentrations of branched-chain amino acids (BCAA) and large neutral amino acids (LNAA) were lower in CFS patients at exhaustion, and for LNAA also during recovery. Consequently, the [free Trp]/[BCAA] and [free Trp]/[LNAA] ratios were significantly higher in CFS patients, except at rest.

On the other hand, levels of tyrosine, the rate-limiting dopaminergic precursor, were significantly lower at all time points in the CFS patients. The significant differences observed in a number of key putative CNS 5-HT and dopaminergic modulators, coupled with the exacerbated perception of effort, provide further evidence for a potentially significant role for CNS mechanisms in the pathogenesis of CFS.

Source: Georgiades E, Behan WM, Kilduff LP, Hadjicharalambous M, Mackie EE, Wilson J, Ward SA, Pitsiladis YP. Chronic fatigue syndrome: new evidence for a central fatigue disorder. Clin Sci (Lond). 2003 Aug;105(2):213-8. http://www.ncbi.nlm.nih.gov/pubmed/12708966

Blood volume and its relation to peak O(2) consumption and physical activity in patients with chronic fatigue

Abstract:

Individuals with chronic fatigue syndrome (CFS) experience a number of somatic complaints including severe, disabling fatigue, and exercise intolerance. We hypothesized that hypovolemia, through its interaction with central hemodynamics, would contribute to the exercise intolerance associated with this disorder. We examined blood volume, peak aerobic power, habitual physical activity, fatigue level, and their interrelations to understand the physiological basis of this disorder.

Seventeen patients who met the Centers for Disease Control criteria for CFS and 17 age-matched controls participated in the study. Blood volume was assessed using a single bolus injection of Evans blue dye. Peak oxygen consumption was measured during exercise on an upright cycle ergometer. Supine cardiac output and stroke volumes were measured using CO(2) rebreathing. Questionnaires were used to assess habitual physical activity and fatigue.

Patients displayed a trend for a 9% lower blood volume (58.3 +/- 2.1 vs. 64.2 +/- 2.5 ml/kg, P = 0.084) and had a 35% lower peak oxygen consumption (22.0 +/- 1.2 vs. 33.6 +/- 1.9 ml/kg, P < 0.001). These two variables were highly related within the patients (r = 0.835, P < 0.001) and the controls (r = 0.850, P < 0.001). Peak ventilation and habitual physical activity were significantly lower in the patients. Fatigue level was not related to any of the measured physiological parameters within the CFS group.

In conclusion, individuals with CFS have a significantly lower peak oxygen consumption and an insignificant trend toward lower blood volume compared with controls. These variables were highly related in both subject groups, indicating that blood volume is a strong physiological correlate of peak oxygen consumption in patients with CFS.

Source: Farquhar WB, Hunt BE, Taylor JA, Darling SE, Freeman R. Blood volume and its relation to peak O(2) consumption and physical activity in patients with chronic fatigue. Am J Physiol Heart Circ Physiol. 2002 Jan;282(1):H66-71. http://ajpheart.physiology.org/content/282/1/H66.long (Full article)