Loading of trained inspiratory muscles speeds lactate recovery kinetics

Purpose: To investigate the effects of inspiratory muscle loading (ITL) and inspiratory muscle training (IMT) upon blood lactate concentration ([lacj]B)and acid-base balance following maximal incremental cycling. Methods: 18 subjects were divided into a control (n = 9) or IMT group (n = 9). Prior to and following a 6 wk intervention subjects completed two maximal incremental cycling tests followed by 20 min of recovery with (ITL) or without (passive recovery; PR) a constant inspiratory resistance (15 cmH2O). The IMT group performed 6 wk pressure threshold IMT at 50% maximal inspiratory mouth pressure (MIP). Throughout recovery, acid-base balance was quantified using the physicochemical approach by measuring the strong ion difference ([SID])=[Na+]+[K+]-[ Clj]+[ lacj]), the total concentration of weak acids ([Atot j]) and the partial pressure of carbon dioxide (PCO2). Results: Following the intervention MIP increased in the IMT group only (+34%). No differences in lactate clearance were observed between PR and ITL before the intervention in both groups and following the intervention in the control group. Following IMT, relative to PR, [lacj]B was reduced throughout ITL (min 2 to 20) by 0.66 ± 1.28 mmol·L-1 (P<0.05) and both the fast (lactate exchange) and slow (lactate clearance) velocity constants of the lactate recovery kinetics were increased (P<0.05). Relative to pre-IMT, ITL reduced plasma [H+] which was accounted for by an IMT-mediated increase in [SID] due almost exclusively to a 1.7 mmol·L-1 reduction in [lacj]B. Conclusions: Following maximal exercise ITL affected lactate recovery kinetics only after IMT. Our data support the notion that the inspiratory muscles are capable of lactate clearance which increases [SID] and reduces [H+]. These effects may facilitate subsequent bouts of high-intensity exercise

Determinants of inspiratory muscle strength in healthy humans

We investigated 1) the relationship between the baseline and inspiratory muscle training (IMT) induced increase in maximal inspiratory pressure (PI,max) and 2) the relative contributions of the inspiratory chest wall muscles and the diaphragm (Poes/Pdi) to PI,max prior to and following-IMT. Experiment 1: PI,max was assessed during a Müeller manoeuvre before and after 4-wk IMT (n=30). Experiment 2: PI,max and the relative contribution of the inspiratory chest wall muscles to the diaphragm (Poes/Pdi) were assessed during a Müeller manoeuvre before and after 4-wk IMT (n=20). Experiment 1: PI,max increased 19% (P<0.01) post-IMT and was correlated with baseline PI,max (r=−0.373, P<0.05). Experiment 2: baseline PI,max was correlated with Poe/Pdi (r=0.582, P<0.05) and after IMT PI,max increased 22% and Poe/Pdi increased 5% (P<0.05). In conclusion, baseline PI,max and the contribution of the chest wall inspiratory muscles relative to the diaphragm affect, in part, baseline and IMT-induced ΔPI,max. Great care should be taken when designing future IMT studies to ensure parity in the between-subject baseline PI,max

Inspiratory muscle training abolishes the blood lactate increase associated with volitional hyperpnoea superimposed on exercise and accelerates lactate and oxygen uptake kinetics at the onset of exercise

We examined the effects of inspiratory muscle training (IMT) upon volitional hyperpnoea-mediated increases in blood lactate ([lac−]B) during cycling at maximal lactate steady state (MLSS) power, and blood lactate and oxygen uptake kinetics at the onset of exercise. Twenty males formed either an IMT (n=10) or control group (n=10). Before and after a 6-wk intervention two 30 min trials were performed at MLSS (207 ± 28 W), which was determined using repeated 30 min constant power trials. The first was a reference trial, whereas during the second trial from 20-28 min participants mimicked the breathing pattern commensurate with 90% of the maximal minute ventilation (V ˙ E) measured during maximal incremental exercise. Before the intervention the MLSS [lac−]B was 3.7 ± 1.8 and 3.9 ± 1.6 mmol·L-1 in the IMT and control group, respectively

Prior upper body exercise reduces cycling work capacity but not critical power

Purpose: This study examined whether metabolite accumulation, induced by prior upper body exercise, affected the power–duration relationship for leg cycle ergometry

Excess returns in the Hong Kong commercial property market

This paper examines the existence of excess returns in the commercial property market of Hong Kong using time series data for both valuations and transactions prices. The proposition is that if the valuation series is accurately processing transactions prices then excess returns, if they exist, should be detected in both series. Our findings confirm that excess returns can be detected in both valuation and transaction based series. The excess returns are not, however, persistent although there appears to be greater opportunities for earning excess returns in the office sector.postprin

Vaccination of Cattle with the N Terminus of LppQ of Mycoplasma mycoides subsp. mycoides Results in Type III Immune Complex Disease upon Experimental Infection

Contagious bovine pleuropneumonia (CBPP) is a serious respiratory disease of cattle caused by Mycoplasma mycoides subsp. mycoides. Current vaccines against CBPP induce short-lived immunity and can cause severe postvaccine reactions. Previous studies have identified the N terminus of the transmembrane lipoprotein Q (LppQ-N') of M. mycoides subsp. mycoides as the major antigen and a possible virulence factor. We therefore immunized cattle with purified recombinant LppQ-N' formulated in Freund's adjuvant and challenged them with M. mycoides subsp. mycoides. Vaccinated animals showed a strong seroconversion to LppQ, but they exhibited significantly enhanced postchallenge glomerulonephritis compared to the placebo group (P = 0.021). Glomerulonephritis was characterized by features that suggested the development of antigen-antibody immune complexes. Clinical signs and gross pathological scores did not significantly differ between vaccinated and placebo groups. These findings reveal for the first time the pathogenesis of enhanced disease as a result of antibodies against LppQ during challenge and also argue against inclusion of LppQ-N' in a future subunit vaccine for CBPP

Response [letter to Editor-in-Chief in response to Chiappa et al.]

We thank Chiappa et al. (4,5) for commending our work (2,3,7), which we reciprocate in light of their thought provoking research that sparked the ensuing trans-Atlantic debate on the effects of inspiratory muscle loading on lactate clearance after exercise. Specifically, despite using similar methodologies, Chiappa et al. (4,5) have twice shown accelerated lactate clearance with inspiratory loading, whereas we have twice shown no effect (2,7). We hypothesized that these discrepancies may be due to interstudy differences in participant endurance training status, as evidenced by higher V˙O2peak and faster blood lactate recovery kinetics in our participants. We were thus intrigued by the authors’ unpublished data showing, in sedentary individuals, no effect of inspiratory loading on lactate clearance. In their accompanying figure, the authors also present novel data showing a significant correlation between maximal inspiratory pressure (MIP) and changes in the area under the blood [Laj] curve with inspiratory loading. This observation informed their hypothesis that the efficacy of inspiratory loading is influenced by inspiratory muscle mass rather than training status

It is not all about being sweet: differences in floral traits and insect visitation among hybrid carrot cultivars

Cytoplasmically male-sterile (CMS) carrot cultivars suffer from low pollination rates. In this study, insect visitation varied more than eightfold between 17 CMS carrot cultivars in a field-based cultivar evaluation trial. The visitation rates of honey bees, nectar scarabs, muscoid flies, and wasps each significantly differed among these cultivars. No significant difference in visitation rates was observed among cultivars of different CMS type (brown-anther or petaloid) or flower colour, but cultivars of Berlicumer root type had significantly higher insect visitation rates than Nantes. Six cultivars were further compared in regard to selected umbel traits: as umbel diameter increased, so did the visitation of soldier beetles, while that of honey bees decreased. Finally, nectar of these six cultivars was analysed for sugar content, which revealed monosaccharides to be the most common sugars in all. There was high variation in the levels of sugars from individual umbellets but no significant difference in nectar sugar composition among cultivars, suggesting that nectar sugar composition is of minor importance regarding pollinator attraction to hybrid CMS carrot umbels

Celestial superamplitudes

We study celestial amplitudes in (super) Yang-Mills theory using a parametrization of the spinor helicity variables where their overall phase is not fixed by the little group action. In this approach the spin constraint h − ¯ h = J for celestial conformal primaries emerges naturally from a new Mellin transform, and the action of conformal transformations on celestial amplitudes is derived. Applying this approach to N = 4 super Yang-Mills, we show how the appropriate definition of on-shell superspace coordinates leads naturally to a formulation of chiral celestial superamplitudes and a representation of the generators of the four-dimensional superconformal algebra on the celestial sphere, which by construction annihilate all tree-level celestial superamplitudes