Chest
Volume 134, Issue 6, December 2008, Pages 1258-1264
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Original Research
Cystic Fibrosis
Androgens, Exercise Capacity, and Muscle Function in Cystic Fibrosis

https://doi.org/10.1378/chest.08-1091Get rights and content

Background

It is well established that muscle strength and exercise capacity are impaired in adults with cystic fibrosis (CF). Numerous factors have been implicated in this process including nutritional factors, disuse, and corticosteroid use. It is also known that serum testosterone levels are frequently low in adolescent male patients with CF. As testosterone is known to have an effect on peripheral muscle, we aimed to assess the relationship among circulating androgen levels, muscle strength, and exercise capacity in adults with CF.

Methods

A prospective observational study was performed. Participants underwent maximal exercise testing and peripheral muscle strength assessment (quadriceps, shoulder flexion, handgrip, maximal inspiratory pressure, and maximal expiratory pressure). Venous blood samples were obtained for the measurement of total testosterone, sex hormone-binding globulin, and albumin. The free testosterone (FT) level was calculated.

Results

A total of 15 subjects completed the study. The patients who were studied had impaired muscle strength and exercise capacity but normal mean androgen levels. Quadriceps strength, SF, and peak oxygen uptake (Vo2max) were 40.1 ± 9.4%, 59.3 ± 20.3%, and 77.4 ± 22.2% predicted, respectively. One patient had a low testosterone level, with low FT levels evident in two subjects. There was no correlation between testosterone or FT level with any of the muscle strengths calculated. Neither testosterone or FT level was correlated with exercise capacity or pulmonary function.

Conclusions

Male CF patients with impaired skeletal muscle strength and exercise capacity have normal testosterone levels. Hypogonadism was rare in this group of adult men with CF. These findings would not support the role of testosterone in muscle dysfunction or impaired exercise capacity in CF patients.

Section snippets

Materials and Methods

A total of 15 adult male patients with CF were recruited from the outpatient department of the National Referral Centre for Adult Cystic Fibrosis at St. Vincent's University Hospital (Dublin, Ireland). The patients chosen for the study were successive stable patients who had been seen in the outpatient department, met the inclusion criteria, and consented to participate in the trial. The mean FEV1 percent predicted was not significantly different from that of our total adult male CF population.

Results

A total of 15 male patients participated in the study. All patients were > 18 years of age at the time of study (mean age, 23.9 years; age range, 19 to 40 years). FEV1 ranged from 31 to 113% predicted. The baseline data are presented in Table 1. No patients were receiving exogenous corticosteroid medication. Four patients were taking inhaled corticosteroids, four patients had diabetes mellitus, and two patients had good diabetic control as indexed by glycosylated hemoglobin levels of 5.4% and

Discussion

We have shown that male patients with CF who have impaired skeletal muscle strength and exercise capacity, and are not routinely treated with corticosteroids, have normal testosterone levels. Furthermore, there is no correlation between testosterone levels and muscle function or exercise capacity. This indicates that androgen deficiency is not a significant contributor to muscle dysfunction in adult male patients with CF.

The etiology of muscle dysfunction in CF patients is not clearly

Conclusions

We have shown that male patients with CF who have impaired skeletal muscle strength and exercise capacity have normal testosterone levels. Hypogonadism was rare in this group of adult male patients with CF. Furthermore, exercise capacity, peripheral, or respiratory muscle strengths were not correlated with circulating total testosterone levels or calculated FT measurements. These findings would not the support the role of testosterone in muscle dysfunction in CF patients and would not support

Acknowledgment

This study was supported by research grants from the Cystic Fibrosis Association of Ireland and the Health Research Board.

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    The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/misc/reprints.shtml).

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