No abstract

This study investigated whether different breathing conditions during exercise testing will influence measures of exercise capacity commonly used for training prescription in chronic obstructive pulmonary disease. Twenty-seven patients with chronic obstructive pulmonary disease (forced expiratory volume in 1 sec = 45.6 [9.4]%) performed three maximal exercise tests within 8 days, but at least 48 hrs apart. Subjects were thereby breathing either room air through a tightly fitting face mask like during any cardiopulmonary exercise test (MASK), room air without mask (No-MASK), or 10 l/min of oxygen via nasal cannula (No-MASK + O2). Cycling protocols were identical for all tests (start = 20 watts, increment = 10 males/5 females watts/min). Maximal work rate (90.4 [33.8], 100.3 [34.8], 107.4 [35.9] watts, P < 0.001) and blood lactate at exhaustion (4.3 [1.5], 5.2 [1.6], 5.0 [1.4] mmol/l, P < 0.001) were lowest for MASK when compared with No-MASK and No-MASK + O2, respectively, whereas maximal heart rate did not differ significantly. Submaximal exertion (Borg rating of perceived exertion = 12-14) was perceived at lower intensity (P = 0.008), but higher heart rate (P = 0.005) when MASK was compared with No-MASK and No-MASK + O2. Different breathing conditions during exercise testing resulted in an 18.8% difference in maximal work rate, likely causing underdosing or overdosing of exercise in chronic obstructive pulmonary disease. Face masks reduced whereas supplemental oxygen increased patients' exercise capacity. For accurate prescription of exercise in chronic obstructive pulmonary disease, breathing conditions during testing should closely match training conditions.

The infra-patellar fat pad (IPFP), as intra-articular adipose tissue represents a potential source of pro-inflammatory cytokines and its size has been suggested to be associated with osteoarthritis (OA) of the knee. This study examines inter- and intra-observer reliability of fat-suppressed (fs) and non-fat-suppressed (nfs) MR imaging for determination of IPFP morphological measurements as novel biomarkers. The IPFP of nine right knees of healthy Osteoarthritis Initiative participants was segmented by five readers, using fs and nfs baseline sagittal MRIs. The intra-observer reliability was determined from baseline and 1-year follow-up images. All segmentations were quality controlled (QC) by an expert reader. Reliability was expressed as root mean square coefficient of variation (RMS CV%). After QC, the inter-observer reliability for fs (nfs) imaging was 2.0% (1.1%) for IPFP volume, 2.1%/2.5% (1.6%/1.8%) for anterior/posterior surface areas, 1.8% (1.8%) for depth, and 2.1% (2.4%) for maximum sagittal area. The intra-observer reliability was 3.1% (5.0%) for volume, 2.3%/2.8% (2.5%/2.9%) for anterior/posterior surfaces, 1.9% (3.5%) for depth, and 3.3% (4.5%) for maximum sagittal area. IPFP volume from nfs images was systematically greater (+7.3%) than from fs images, but highly correlated (r = 0.98). The results suggest that quantitative measurements of IPFP morphology can be performed with satisfactory reliability when expert QC is implemented. The IPFP is more clearly depicted in nfs images, and there is a small systematic off-set versus analysis from fs images. However, the high linear relationship between fs and nfs imaging suggests that fs images can be used to analyze IPFP morphology, when nfs images are not available.