Biomedical subjects

Attila Somfay

Publications and source records attributed to Attila Somfay.

4 recordsLinked to original sources

PubMed2004

Effects of testosterone and resistance training in men with chronic obstructive pulmonary disease.

Dysfunction of the muscles of ambulation contributes to exercise intolerance in chronic obstructive pulmonary disease (COPD). Men with COPD have high prevalence of low testosterone levels, which may contribute to muscle weakness. We determined effects of testosterone supplementation (100 mg of testosterone enanthate injected weekly) with or without resistance training (45 minutes three times weekly) on body composition and muscle function in 47 men with COPD (mean FEV(1) = 40% predicted) and low testosterone levels (mean = 320 ng/dl). Subjects were randomized to 10 weeks of placebo injections + no training, testosterone injections + no training, placebo injections + resistance training, or testosterone injections + resistance training. Testosterone injections yielded a mean increase of 271 ng/dl in the nadir serum testosterone concentration (to the middle of the normal range for young men). The lean body mass (by dual-energy X-ray absorptiometry) increase averaged 2.3 kg with testosterone alone and 3.3 kg with combined testosterone and resistance training (p < 0.001). Increase in one-repetition maximum leg press strength averaged 17.2% with testosterone alone, 17.4% with resistance training alone, and 26.8% with testosterone + resistance training (p < 0.001). Interventions were well tolerated with no abnormalities in safety measures. Further studies are required to determine long-term benefits of adding testosterone supplementation and resistance training to rehabilitative programs for carefully screened men with COPD and low testosterone levels.

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PubMed2003

Benefits of supplemental oxygen in exercise training in nonhypoxemic chronic obstructive pulmonary disease patients.

Supplemental oxygen improves exercise tolerance of normoxemic and hypoxemic chronic obstructive pulmonary disease (COPD) patients. We determined whether nonhypoxemic COPD patients undergoing exercise training while breathing supplemental oxygen achieve higher intensity and therefore improve exercise capacity more than patients breathing air. A double-blinded trial was performed involving 29 nonhypoxemic patients (67 years, exercise SaO2 > 88%) with COPD (FEV1 = 36% predicted). All exercised on cycle ergometers for 45 minutes, 3 times per week for 7 weeks at high-intensity targets. During exercise, they received oxygen (3 L/minute) (n = 14) or compressed air (3 L/minute) (n = 15). Both groups had a higher exercise tolerance after training and when breathing oxygen. However, the oxygen-trained group increased the training work rate more rapidly than the air-trained group. The mean +/- SD work rate during the last week was 62 +/- 19 W (oxygen-trained group) and 52 +/- 22 W (air-trained group) (p < 0.01). After training, endurance in constant work rate tests increased more in the oxygen-trained group (14.5 minutes) than in the air-trained group (10.5 minutes) (p < 0.05). At isotime, the breathing rate decreased four breaths per minute in the oxygen-trained group and one breath per minute in the air-trained group (p = 0.001). We conclude that supplemental oxygen provided during high-intensity training yields higher training intensity and evidence of gains in exercise tolerance in laboratory testing.

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PubMed2003

A treadmill ramp protocol using simultaneous changes in speed and grade.

INTRODUCTION: A treadmill exercise test requiring a low initial metabolic rate that then increments the work rate linearly to reach the subject's limit of tolerance in approximately 10 min would have significant advantages for exercise testing and rehabilitation of subjects with impaired exercise tolerance. METHODS: We developed such a treadmill protocol that uses a linear increase in walking speed coupled with a curvilinear increase in treadmill grade to yield a linear increase in work rate. RESULTS: Twenty-two healthy, sedentary subjects performed both this new treadmill protocol and a standard cycle ergometry ramp protocol eliciting similar work rate profiles. The low initial treadmill speed and grade resulted in a low initial metabolic rate, commensurate with unloaded pedaling on a cycle ergometer (average [OV0312]O2 = 0.54 +/- 0.16 vs 46 +/- 0.12 l x min(-1)). This combination of simultaneous increase in speed and grade yielded a linear work rate and its oxygen uptake response (R2 = 0.96 +/- 0.03) with a slope of 11.4 +/- 2.4 ml x min(-1) x W(-1)-slightly, but significantly, higher than on the cycle (9.6 +/- 2.0 ml x min(-1) x W(-1)). This difference was attributed to unmeasured work associated, for example, with additional limb movements and frictional losses. As previously demonstrated, both the peak oxygen uptake and the estimated lactate threshold were higher on the treadmill than for cycle ergometry (averaging 23% and 27%, respectively, in these subjects). CONCLUSION: This treadmill protocol provides a linear profile of work rate as is currently standard for cycle ergometry and is appropriate for testing of subjects with low exercise tolerance.

Adolescent↗

PubMed2002

Effect of hyperoxia on gas exchange and lactate kinetics following exercise onset in nonhypoxemic COPD patients.

STUDY OBJECTIVES: The slow oxygen uptake (VO(2)) kinetics observed in COPD patients is a manifestation of skeletal muscle dysfunction of multifactorial origin. We determined whether oxygen supplementation during exercise makes the dynamic VO(2) response faster and reduces transient lactate increase. DESIGN: Ten patients with severe COPD (ie, mean [+/- SD] FEV(1), 31 +/- 10% predicted) and 7 healthy subjects of similar age performed four repetitions of the transition between rest and 10 min of moderate-intensity, constant-work rate exercise while breathing air or 40% oxygen in random order. Minute ventilation (VE), gas exchange, and heart rate (HR) were recorded breath-by-breath, and arterialized venous pH, PCO(2), and lactate levels were measured serially. RESULTS: Compared to healthy subjects, the time constants (tau) for VO(2), HR, carbon dioxide output (VCO(2)), and VE kinetic responses were significantly slower in COPD patients than in healthy subjects (70 +/- 8 vs 44 +/- 3 s, 98 +/- 14 vs 44 +/- 8 s, 86 +/- 8 vs 61 +/- 4 s, and 81 +/- 7 vs 62 +/- 4 s, respectively; p < 0.05). Hyperoxia decreased end-exercise E in the COPD group but not the healthy group. Hyperoxia did not increase the speed of VO(2) kinetics but significantly slowed VCO(2) and E response dynamics in both groups. Only small increases in lactate occurred with exercise, and this increase did not correlate with the tau for VO(2). CONCLUSION: In nonhypoxemic COPD patients performing moderate exercise, the lower ventilatory requirement induced by oxygen supplementation is not related to improved muscle function but likely stems from direct chemoreceptor inhibition.

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