Assessment of maximum inspiratory pressure: Prior submaximal respiratory muscle activity (‘warm-up’) enhances maximum inspiratory activity and attenuates the learning effect of repeated measurement

The official published version can be obtained from the link belowBackground: The variability of maximal inspiratory pressure (PImax) in response to repeated measurement affects its reliability; published studies have used between three and twenty PImax measurements on a single occasion. Objective: This study investigated the influence of a specific respiratory ‘warm-up’ upon the repeated measurement of inspiratory muscle strength and attempts to establish a procedure by which PImax can be assessed with maximum reliability using the smallest number of manoeuvres. Methods: Fourteen healthy subjects, familiar with the Mueller manoeuvre, were studied. The influence of repeated testing on a single occasion was assessed using an 18-measurement protocol. Using a randomised cross-over design, subjects performed the protocol, preceded by a specific respiratory warm-up (RWU) and on another occasion, without any preliminary activity (control). Comparisons were made amongst ‘baseline’ (best of the first 3 measurements), ‘short’ series (best of 7th to 9th measurement) and ‘long’ series (best of the last 3 measurements). Results: Under control conditions, the mean increase (‘baseline’ vs. ‘long’ series) was 11.4 (5.8)%; following the RWU, the increase (post RWU ‘baseline’ vs. ‘long’ series) was 3.2 (10.0)%. There were statistically significant differences between measurements made at all 3 protocol stages (‘baseline’, ‘short’ and ‘long’ series) under control conditions, but none following the RWU. Conclusions: The present data suggest that a specific RWU may attenuate the ‘learning effect’ during repeated PImax measurements, which is one of the main contributors of the test variability. The use of a RWU may provide a means of obtaining reliable values of PImax following just 3 measurements.This work was partially supported by a grant from the University of Wolverhampton, UK

Whole body active warm up and inspiratory muscle warm up do not improve running performance when carrying thoracic loads

Whole body active warm ups (AWU) and inspiratory muscle warm up (IMW) prior to exercise improves performance on some endurance exercise tasks. This study investigated the effects of AWU with and without IMW upon 2.4 km running time-trial performance while carrying a 25 kg backpack, a common task and backpack load in physically demanding occupations. Participants (n = 9) performed five 2.4 km running time-trials with a 25 kg thoracic load preceded in random order by 1) IMW comprising 2 x 30 inspiratory efforts against a pressure-threshold load of 40 % maximal inspiratory pressure (PImax), 2) 10 min unloaded running (AWU) at lactate turnpoint (10.33 ± 1.58 km·h-1), 3) placebo IMW (PLA) comprising five min breathing using a sham device, 4) AWU+IMW and 5) AWU+PLA. Pooled baseline PImax was similar between trials and increased by 7% and 6% following IMW and AWU+IMW (P0.05). Time-trial performance was not different between any trials. Whole body AWU and IMW performed alone or combination have no ergogenic effect upon high intensity, short duration performance when carrying a 25 kg load in a backpack.N/

Cardiac output during exercise related to plasma atrial natriuretic peptide but not to central venous pressure in humans.

NEW FINDINGS: What is the central question of this study? Is cardiac output during exercise dependent on central venous pressure? What is the main finding and its importance? The increase in cardiac output during both rowing and running is related to preload to the heart as indicated by plasma atrial natriuretic peptide but unrelated to central venous pressure. The results indicate that in upright humans central venous pressure reflects the gravitational influence on central venous blood rather than preload to the heart. ABSTRACT: Aim This study evaluated the increase in cardiac output (CO) during exercise in relation to central venous pressure (CVP) and plasma arterial natriuretic peptide (ANP) as expressions of preload to the heart. Methods Seven healthy subjects (four men; 26 ± 3 years; 181± 8 cm height; and 76 ± 11 kg, weight; mean ± SD) rested in sitting and standing positions (in randomized order) and then rowed and ran at submaximal workloads. The CVP was recorded, CO (Modelflow) calculated, and arterial plasma ANP determined by radioimmunoassay. Results While sitting CO was 6.2 ± 1.6 l/min, plasma ANP 70 ± 10 pg/ml, and CVP 1.8 ± 1.1 mmHg (mean ± SD) and decreased to 5.9 ± 1.0 l/min, 63 ± 10 pg/ml, and -3.8 ± 1.2 mmHg, respectively when standing (P < 0.05). Ergometer rowing elicited an increase in CO to 22.5 ± 5.5 l/min as plasma ANP increased to 156 ± 11 pg/ml and CVP to 3.8 ± 0.9 mmHg (P < 0.05). Similarly, CO increased to 23.5 ± 6.0 l/min during running with albeit smaller (P < 0.05) increase in plasma ANP, but with little change in CVP (-0.9 ± 0.4 mmHg). Conclusion The increase in CO in response to exercise is related to preload to the heart as indicated by plasma ANP, but unrelated to CVP. The results indicate that in upright humans CVP reflects the gravitational influence on central venous blood rather than preload to the heart. This article is protected by copyright. All rights reserved

Inspiratory muscle warm-up does not improve cycling time-trial performance

Purpose: This study examined the effects of an active cycling warm-up, with and without the addition of an inspiratory muscle warm-up (IMW), on 10-km cycling time-trial performance

Inspiratory muscle training reduces blood lactate concentration during volitional hyperpnoea

Although reduced blood lactate concentrations ([lac−]B) have been observed during whole-body exercise following inspiratory muscle training (IMT), it remains unknown whether the inspiratory muscles are the source of at least part of this reduction. To investigate this, we tested the hypothesis that IMT would attenuate the increase in [lac−]B caused by mimicking, at rest, the breathing pattern observed during high-intensity exercise. Twenty-two physically active males were matched for 85% maximal exercise minute ventilation (V˙Emax) and divided equally into an IMT or a control group. Prior to and following a 6 week intervention, participants performed 10 min of volitional hyperpnoea at the breathing pattern commensurate with 85% V˙Emax

Thoracic load carriage-induced respiratory muscle fatigue.

We investigated the effect of carrying a 25 kg backpack upon exercise-induced respiratory muscle fatigue, pulmonary function and physiological and perceptual responses to exercise.N/

The effect of arm training on thermoregulatory responses and calf volume during upper body exercise

The final publication is available at Springer via https://doi.org/10.1007/s00421-014-2842-9.PURPOSE: The smaller muscle mass of the upper body compared to the lower body may elicit a smaller thermoregulatory stimulus during exercise and thus produce novel training-induced thermoregulatory adaptations. Therefore, the principal aim of the study was to examine the effect of arm training on thermoregulatory responses during submaximal exercise. METHODS: Thirteen healthy male participants (Mean ± SD age 27.8 ± 5.0 years, body mass 74.8 ± 9.5 kg) took part in 8 weeks of arm crank ergometry training. Thermoregulatory and calf blood flow responses were measured during 30 min of arm cranking at 60% peak power (W peak) pre-, and post-training and post-training at the same absolute intensity as pre-training. Core temperature and skin temperatures were measured, along with heat flow at the calf, thigh, upper arm and chest. Calf blood flow using venous occlusion plethysmography was performed pre- and post-exercise and calf volume was determined during exercise. RESULTS: The upper body training reduced aural temperature (0.1 ± 0.3 °C) and heat storage (0.3 ± 0.2 J g(-1)) at a given power output as a result of increased whole body sweating and heat flow. Arm crank training produced a smaller change in calf volume post-training at the same absolute exercise intensity (-1.2 ± 0.8% compared to -2.2 ± 0.9% pre-training; P < 0.05) suggesting reduced leg vasoconstriction. CONCLUSION: Training improved the main markers of aerobic fitness. However, the results of this study suggest arm crank training additionally elicits physiological responses specific to the lower body which may aid thermoregulation.Peer reviewedFinal Accepted Versio

Commentaries on viewpoint : physiology and fast marathons

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