Correlation between lung function tests and peak oxygen consumption in post-TB lung disease.

BACKGROUND: After TB treatment, many patients have post-TB lung disease (PTLD), associated with increased mortality and morbidity. Nevertheless, relationships between lung function testing and exercise capacity in people with PTLD are poorly understood.METHODS: This single-centre study investigated the association between lung function testing and peak oxygen consumption (VO2peak) and percentage-predicted VO2peak (VO2peak (%pred)) in adults with PTLD investigated for surgery.RESULTS: Eighty-two patients (52 males, 30 females) with a mean age of 43.2 years (SD 11.3) were included. Spirometric values of forced vital capacity (FVC) percentage predicted (%pred) and forced expiratory volume in 1 sec (FEV1) %pred suggested significant correlations with VO2peak (%pred) (P < 0.001 and P < 0.001), whereas FEV1/FVC did not. Diffusing capacity for carbon monoxide (DLCO) %pred also correlated significantly with VO2peak (%pred) (P = 0.002). However, the magnitude of all significant correlation coefficients were weak. No significant correlations for any plethysmographic values with VO2peak (%pred) could be robustly concluded. Correlations with VO2peak (ml/kg/min) for most physiological variables were less robust than for VO2peak (%pred).CONCLUSIONS: Although statistically significant, the correlations between any measure of lung function and VO2peak or VO2peak (%pred) were weak, with only FVC correlation coefficient surpassing 0.50.

Soleus muscle stability in wild hibernating black bears.

Based on studies of fast skeletal muscles, hibernating black and brown bears resist skeletal muscle atrophy during months of reduced physical activity and not feeding. The present study examined atrophy sparing in the slow soleus muscle, known to be highly prone to disuse atrophy in humans and other mammals. We demonstrated histochemically that the black bear soleus is rich in slow fibers, averaging 84.0 ± 6.6%. The percentages of slow fibers in fall (87.3 ± 4.9%) and during hibernation (87.1 ± 5.6%) did not differ ( P = 0.3152) from summer. The average fiber cross-sectional area to body mass ratio (48.6 ± 11.7 µm2/kg) in winter hibernating bears was not significantly different from that of summer (54.1 ± 11.8 µm2/kg, P = 0.4186) and fall (47.0 ± 9.7 µm2/kg, P = 0.9410) animals. The percentage of single hybrid fibers containing both slow and fast myosin heavy chains, detected biochemically, increased from 2.6 ± 3.8% in summer to 24.4 ± 24.4% ( P = 0.0244) during hibernation. The shortening velocities of individual hybrid fibers remained unchanged from that of pure slow and fast fibers, indicating low content of the minority myosins. Slow and fast fibers in winter bears exhibited elevated specific tension (kN/m2; 22%, P = 0.0161 and 11%, P = 0.0404, respectively) and maintained normalized power. The relative stability of fiber type percentage and size, fiber size-to-body mass ratio, myosin heavy chain isoform content, shortening velocity, power output, and elevated specific tension during hibernation validates the ability of the black bear to preserve the biochemical and performance characteristics of the soleus muscle during prolonged hibernation.