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Background-Exercise testing has become an important tool in the diagnosis and treatment of restrictive lung disease. The reproducibility of variables measured during exercise testing was examined in subjects with stable restrictive lung disease. Methods-Six subjects, who had never previously undergone exercise testing, each underwent three maximal incremental exercise studies on a bicycle ergometer conducted during a 28 day period. Results-Data collected at rest, before exercise, were not significantly different during the three study days. Comparison of results at the end of the exercise tests from the three studies also revealed no evidence of a significant learning effect. Reproducibility of exercise performance by subjects was assessed by the coefficient of variation. The mean within subject coefficient of variation at the end of the exercise tests was 5'6% for work rate, 7-9% for exercise duration, and 9 5% for dyspnoea. The mean within subject coefficient of variation obtained at the end of the exercise tests was 5-3% for oxygen uptake (Vo2), 2-5% for oxygen saturation (Sao,), 4-0% for heart rate (HR), 5.5% for minute ventilation (VE), 5-8% for respiratory frequency (f), and 4'6% for tidal volume (VT). The mean within subject coefficient of variation at 40% and 70% of maximal work rates for Vo, was 5-7% and 5-6% respectively, for Sao, 13% and 1-5%, for HR 4*8% and 4 0%, for VE 6-3% and 6-6%, for f 101% and 7S8%, and for VT 6X0% and 4-5%. Conclusions-Variables measured during clinical exercise testing in subjects with restrictive lung disease are highly reproducible. No significant learning effect was found on repeated testing in subjects who had never previously undergone exercise testing. (Thorax 1993;48:894-898)

Dead space (VD) loading has been shown to cause an increase in tidal volume and a decrease in respiratory frequency at moderate to high levels of ventilation (VI) during exercise (J. Appl. Physiol. 70: 55-62, 1991). This study examined the role of carotid chemoreceptors (CC) in the breathing pattern response to added VD during maximal incremental exercise; we used hyperoxia to silence the CC. Nine healthy subjects exercised on a bicycle ergometer on 4 different days while inspiring air with VD (AVD) and without VD [air control (AC)] and while inspiring 100% O2 with VD (O2VD) and without VD (O2C). Equipment resistance for VD and control studies was identical, and the exercise tests were done in a randomized order. At a matched level of VI equivalent to 75% VI at the end of the AC experiments (102 l/min), the breathing pattern in the AVD and O2VD tests was significantly deeper and slower (P < 0.05) than that in the AC and O2C tests. The difference in tidal volume between AVD and AC tests (delta = 0.26 +/- 0.16 liter) was not significantly different from that between O2VD and O2C tests (delta = 0.23 +/- 0.23 liter). The breathing pattern was the same in the AC and O2C tests. It is concluded that the altered breathing pattern with VD loading is not mediated by the CC.

A French univoltine and a Canadian partially bivoltine strain of the alfalfa leafcutting bee were field tested near Ontario, Oregon. Prepupae were sampled on July 31 and Aug. 27. On both dates the univoltine strain showed a higher % of healthy prepupae (83 and 80%) compared to the bivoltine strain (67 and 48%). An increased diapause intensity of the univoltine strain resulted in a reduced summer‐emergent generation at both dates. The percentage of univoltine prepupae infected with sporulating chalkbrood on both sampling dates was 1 and 1.3 % compared to 5 % (July 31) and 12.3 % (Aug. 27) for the bivoltine strain. The univoltine's 10‐fold increased chalkbrood resistance on Aug. 27 was due to two factors: (i) intrinsic tolerance to the fungal pathogen and (ii) a reduction in spore contamination of cells constructed by the summer‐emergent generation. The magnitude of univoltine strain resistance to chalkbrood makes its use an addendum in the management of this disease. Zusammenfassung Zur Kalkhrut‐(Ascosphaera aggregata Skou.) Resistenz eines univoltinen Stammes der Alfalfa‐Blattschneiderbiene, Megachile rotundata F. Es wurden bei Ontario, Oregon, Freilanduntersuchungen an einem französischen univokinen und einem kanadischen partiell bivoltinen Stamm der Alfalfa‐Blattschneiderbiene durchgeführt. Präpuppen wurden am 31.7. und 27.8. gesammelt. An beiden Daten zeigte der univoltine Stamm einen höheren Prozentsatz gesunder Präpuppen (83 und 80 %) als der bivoltine Stamm (67 und 48 %). Eine zunehmende Diapause des univokinen Stammes führte bei beiden Sammelarten zu einer Reduzierung der im Sommer schlüpfenden Generation. Der Anteil an univokinen Präpuppen mit sporulierenden Kalkbruterregern betrug nur 1 und 1,3 % gegenüber 5 und 12,3 % beim bivoltinen Stamm. Die 10fach höhere Kalkbrutresistenz des univokinen Stammes am 27.8. beruhte auf zwei Faktoren: 1. der geringeren Toleranz gegenüber dem pathogenen Pilz und 2. der Verringerung der Sporenkontamination der Brutzellen, erbaut von der im Sommer geschlüpften Generation. Die Größe der Univoltinstammresistenz gegen Kalkbrut macht sie zu einem wichtigen Faktor bei der Bekämpfung dieser Krankheit.