Hyperpnea training attenuates peripheral chemosensitivity and improves cycling endurance

2002 ◽  
Vol 205 (24) ◽  
pp. 3937-3943
Author(s):  
Michael E. McMahon ◽  
Urs Boutellier ◽  
Richard M. Smith ◽  
Christina M. Spengler
Keyword(s):  
Minute Ventilation ◽  
Work Capacity ◽  
Cycling Performance ◽  
Respiratory Muscle Training ◽  
Whole Body ◽  
Control Group ◽  
Peripheral Chemoreceptor ◽  
Endurance Time ◽  
Exercise Ventilation

SUMMARY Well-trained endurance athletes frequently have a lower peripheral chemoreceptor (pRc) sensitivity and a lower minute ventilation(V̇E) during exercise compared to untrained individuals. We speculated that the decreased pRcresponse may be specifically associated with repeated exposure to the high rates of ventilation occurring during exercise training. We therefore examined the effect of respiratory muscle training (RMT; 20× 30 min sessions of voluntary normocapnic hyperpnea) on the pRc sensitivity during exercise and on cycling performance. RMT was chosen to achieve a high V̇E, similar to that of heavy exercise,while avoiding the other accompanying effects of whole body exercise. 20 trained male cyclists were randomized into RMT (N=10) or control(N=10) groups. Subjects' pRc response was assessed by a modified Dejours O2 test (10-12 breaths of 100% O2,repeated 4-6 times) during cycling exercise at 40% of the maximal work capacity (Ẇmax). Cycling performance was measured during a cycling test to exhaustion (85%Ẇmax). The RMT group exhibited a significantly reduced pRc sensitivity (mean ±S.D.) compared to the control group (-5.8±6.0% versus0.1±4.6%, P<0.5). Cycling endurance improved significantly after RMT in comparison to the control group (+3.26±4.98 versus -1.46±3.67 min, P<0.05). However, these changes in pRc response were not significantly correlated with exercise ventilation or cycling endurance time. We conclude that the high levels of ventilation achieved during exercise, as simulated by RMT in this study, appear to be accompanied by a reduction in pRc sensitivity;however, the role of the pRc in the control of ventilation during exercise seems to be minor.

Skin Cooling on Breath-Hold Duration and Predicted Emergency Air Supply Duration During Immersion

2020 ◽  
Vol 91 (7) ◽  
pp. 578-585
Author(s):  
Victory C. Madu ◽  
Heather Carnahan ◽  
Robert Brown ◽  
Kerri-Ann Ennis ◽  
Kaitlyn S. Tymko ◽  
...  
Keyword(s):  
Minute Ventilation ◽  
Hold Time ◽  
Whole Body ◽  
Breath Hold ◽  
Endurance Time ◽  
Skin Exposure ◽  
Breathing Apparatus ◽  
Air Supply ◽  
Skin Cooling ◽  
Breath Hold Duration

PURPOSE: This study was intended to determine the effect of skin cooling on breath-hold duration and predicted emergency air supply duration during immersion.METHODS: While wearing a helicopter transport suit with a dive mask, 12 subjects (29 ± 10 yr, 78 ± 14 kg, 177 ± 7 cm, 2 women) were studied in 8 and 20°C water. Subjects performed a maximum breath-hold, then breathed for 90 s (through a mouthpiece connected to room air) in five skin-exposure conditions. The first trial was out of water for Control (suit zipped, hood on, mask off). Four submersion conditions included exposure of the: Partial Face (hood and mask on); Face (hood on, mask off); Head (hood and mask off); and Whole Body (suit unzipped, hood and mask off).RESULTS: Decreasing temperature and increasing skin exposure reduced breath-hold time (to as low as 10 ± 4 s), generally increased minute ventilation (up to 40 ± 15 L · min−1), and decreased predicted endurance time (PET) of a 55-L helicopter underwater emergency breathing apparatus. In 8°C water, PET decreased from 2 min 39 s (Partial Face) to 1 min 11 s (Whole Body).CONCLUSION: The most significant factor increasing breath-hold and predicted survival time was zipping up the suit. Face masks and suit hoods increased thermal comfort. Therefore, wearing the suits zipped with hoods on and, if possible, donning the dive mask prior to crashing, may increase survivability. The results have important applications for the education and preparation of helicopter occupants. Thermal protective suits and dive masks should be provided.Madu VC, Carnahan H, Brown R, Ennis K-A, Tymko KS, Hurrie DMG, McDonald GK, Cornish SM, Giesbrecht GG. Skin cooling on breath-hold duration and predicted emergency air supply duration during immersion. Aerosp Med Hum Perform. 2020; 91(7):578–585.

scholarly journals Special Training of Inspiratory Muscles in Fitness Activities and Exercise Capacity in Young Women

2017 ◽  
Vol 18 (3) ◽  
Author(s):  
Viktor Mishchenko ◽  
Stanislaw Sawczyn ◽  
Agnieszka Cybulska ◽  
Marcin Pasek
Keyword(s):  
Oxygen Uptake ◽  
Exercise Capacity ◽  
Young Women ◽  
Vital Capacity ◽  
Perceived Exertion ◽  
Minute Ventilation ◽  
Work Capacity ◽  
Control Group ◽  
Inspiratory Muscles ◽  
Fitness Training

AbstractPurpose. The aim of the study was to determine if an 8-week-long endurance fitness training with elastic belts would increase the strength-endurance of the inspiratory muscles and lung function characteristics, and to assess whether these changes were consistent with an increase in aerobic power and exercise capacity in healthy young women. Methods. Twenty-two females aged 20-25 years were randomly allocated into 2 groups. The experimental group preformed 8-week-long exercises on stationary bikes with an elastic belt on the lower part of the chest. The control group underwent the same workout, without elastic belts. Vital capacity, forced vital capacity, maximal voluntary ventilation, maximal inspiratory and expiratory pressure, sustained maximal inspiratory pressure, physical activity status, and perceived exertion scores were measured. In the incremental exercise test, work capacity and maximal oxygen uptake were assessed. Tidal volume, minute ventilation (VE), oxygen uptake (VO

Ventilatory response to hyperoxia in newborn mice heterozygous for the transcription factor Phox2b

2006 ◽  
Vol 290 (6) ◽  
pp. R1691-R1696 ◽  
Author(s):  
N. Ramanantsoa ◽  
V. Vaubourg ◽  
S. Dauger ◽  
B. Matrot ◽  
G. Vardon ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Ventilatory Response ◽  
Minute Ventilation ◽  
Whole Body ◽  
Wild Type ◽  
Peripheral Chemoreceptor ◽  
Newborn Mice ◽  
Apnea Duration ◽  
Autonomic Reflex ◽  
Hypoventilation Syndrome

Heterozygous mutations of the transcription factor PHOX2B have been found in most patients with central congenital hypoventilation syndrome, a rare disease characterized by sleep-related hypoventilation and impaired chemosensitivity to sustained hypercapnia and sustained hypoxia. PHOX2B is a master regulator of autonomic reflex pathways, including peripheral chemosensitive pathways. In the present study, we used hyperoxic tests to assess the strength of the peripheral chemoreceptor tonic drive in Phox2b+/− newborn mice. We exposed 69 wild-type and 67 mutant mice to two hyperoxic tests (12-min air followed by 3-min 100% O2) 2 days after birth. Breathing variables were measured noninvasively using whole body flow plethysmography. The initial minute ventilation decrease was larger in mutant pups than in wild-type pups: −37% (SD 13) and −25% (SD 18), respectively, P < 0.0001. Furthermore, minute ventilation remained depressed throughout O2 exposure in mutants, possibly because of their previously reported impaired CO2 chemosensitivity, whereas it returned rapidly to the normoxic level in wild-type pups. Hyperoxia considerably increased total apnea duration in mutant compared with wild-type pups ( P = 0.0001). A complementary experiment established that body temperature was not influenced by hyperoxia in either genotype group and, therefore, did not account for genotype-related differences in the hyperoxic ventilatory response. Thus partial loss of Phox2b function by heterozygosity did not diminish the tonic drive from peripheral chemoreceptors.

Effects of oxone inhalation on work performance and VO2 max

1979 ◽  
Vol 46 (2) ◽  
pp. 309-314 ◽  
Author(s):  
W. M. Savin ◽  
W. C. Adams
Keyword(s):  
Pulmonary Function ◽  
Work Performance ◽  
Minute Ventilation ◽  
Pulmonary Function Tests ◽  
Work Capacity ◽  
Forced Expiratory Volume ◽  
Function Parameter ◽  
Exercise Ventilation ◽  
Dose Dependent Fashion ◽  
Volitional Fatigue

Ozone (O3) at near ambient smog alert levels has previously been shown to cause alterations in pulmonary function and exercise response in humans. The present study was designed to investigate the effects of O3 administered during graded bicycle exercise to volitional fatigue on work performance and maximal oxygen uptake (VO2max). Nine subjects performed three tests each while breathing either 0.00, 0.15, or 0.30 ppm O3. Forced vital capacity, residual volume, maximal midexpiratory flow rate, and forced expiratory volume in 1 s were assessed before, immediately after, and 4 h after exercise. O3 exposure resulted in no significant effect on maximal work rate, anaerobic threshold, or any pulmonary function parameter. However, maximal expired minute ventilation was decreased (P less than 0.05) in a dose dependent fashion. Thus, exercise ventilation during maximal work was a more sensitive indicator of the effects of O2 exposure than were standard pulmonary function tests. Although subjective symptoms of discomfort were reported more frequently with increased O2 level, it was concluded that exposure of healthy young men to as much as 0.30 ppm O2 for no more than 30 min of progressively incremented exercise to volitional fatigue, is insufficient to cause a significant decrease in work capacity or V02 max.

scholarly journals Respiratory energetics during exercise at high altitude

1999 ◽  
Vol 86 (6) ◽  
pp. 1785-1792 ◽  
Author(s):  
Fabio Cibella ◽  
Giuseppina Cuttitta ◽  
Salvatore Romano ◽  
Bruno Grassi ◽  
Giovanni Bonsignore ◽  
...  
Keyword(s):  
High Altitude ◽  
Minute Ventilation ◽  
Work Of Breathing ◽  
Normal Subjects ◽  
Mechanical Efficiency ◽  
Esophageal Pressure ◽  
Work Capacity ◽  
External Work ◽  
Exercise Ventilation ◽  
The Relationship

The purpose of this study was to assess the effect of high altitude (HA) on work of breathing and external work capacity. On the basis of simultaneous records of esophageal pressure and lung volume, the mechanical power of breathing (W˙rs) was measured in four normal subjects during exercise at sea level (SL) and after a 1-mo sojourn at 5,050 m. Maximal exercise ventilation (V˙e max) and maximal W˙rs were higher at HA than at SL (mean 185 vs. 101 l/min and 129 vs. 40 cal/min, respectively), whereas maximal O2 uptake averaged 2.07 and 3.03 l/min, respectively. In three subjects, the relationship ofW˙rs to minute ventilation (V˙e) was the same at SL and HA, whereas, in one individual, W˙rs for any givenV˙e was consistently lower at HA. Assuming a mechanical efficiency (E) of 5%, the O2 cost of breathing at HA and SL should amount to 26 and 5.5% of maximal O2 uptake, whereas for E of 20% the corresponding values were 6.5 and 1.4%, respectively. Thus, at HA, W˙rs may substantially limit external work unless E is high. Although at SLV˙e max did not exceed the critical V˙e, at which any increase inV˙e is not useful in terms of body energetics even for E of 5%, at HAV˙e maxexceeded critical V˙e even for E of 20%.

scholarly journals Chronic Effects of a Training Program Using a Nasal Inspiratory Restriction Device on Elite Cyclists

2021 ◽  
Vol 18 (2) ◽  
pp. 777
Author(s):  
Jose L. Gonzalez-Montesinos ◽  
Jorge R. Fernandez-Santos ◽  
Carmen Vaz-Pardal ◽  
Ruben Aragon-Martin ◽  
Aurelio Arnedillo-Muñoz ◽  
...  
Keyword(s):  
Peak Power ◽  
Performance Enhancement ◽  
Minute Ventilation ◽  
Respiratory Muscle Training ◽  
Control Group ◽  
Ventilatory Efficiency ◽  
Partial Pressure Of Co2 ◽  
End Tidal ◽  
Cycling Training ◽  
Elite Cyclists

This study compared the response of a 9-week cycling training on ventilatory efficiency under two conditions: (i) Combined with respiratory muscle training (RMT) using a new nasal restriction device (FeelBreathe) (FB group) and (ii) without RMT (Control group). Eighteen healthy elite cyclists were randomly separated into the FB group (n = 10) or Control group (n = 8). Gas exchange was measured breath by breath to measure ventilatory efficiency during an incremental test on a cycloergometer before (Pre) and after (Post) the nine weeks of training. The FB group showed higher peak power (Δ (95%HDI) (0.82 W/kg (0.49, 1.17)), VO2max (5.27 mL/kg/min (0.69, 10.83)) and VT1 (29.3 W (1.8, 56.7)) compared to Control at PostFINAL. The FB group showed lower values from Pre to PostPRE in minute ventilation (VE) (−21.0 L/min (−29.7, −11.5)), Breathing frequency (BF) (−5.1 breaths/min (−9.4, −0.9)), carbon dioxide output (VCO2) (−0.5 L/min (−0.7, −0.2)), respiratory equivalents for oxygen (EqO2) (−0.8 L/min (−2.4, 0.8)), heart rate (HR) (−5.9 beats/min (−9.2, −2.5)), respiratory exchange ratio (RER) (−0.1 (−0.1, −0.0) and a higher value in inspiratory time (Tin) (0.05 s (0.00, 0.10)), expiratory time (Tex) (0.11 s (0.05, 0.17)) and end-tidal partial pressure of CO2 (PETCO2) (0.3 mmHg (0.1, 0.6)). In conclusion, RMT using FB seems to be a new and easy alternative ergogenic tool which can be used at the same time as day-to-day training for performance enhancement.

The role of melatonin and carnosine in prevention of oxidative intestinal injury induced by gamma irradiation in rats

Biologia ◽  
2017 ◽  
Vol 72 (8) ◽  
Author(s):  
Omur Karabulut-Bulan ◽  
Huseyin Us ◽  
Bertan Boran Bayrak ◽  
Ayca Sezen-Us ◽  
Refiye Yanardag
Keyword(s):  
Gamma Irradiation ◽  
Cell Number ◽  
Whole Body ◽  
Nuclear Antigen ◽  
Control Group ◽  
Albino Rats ◽  
Intestinal Damage ◽  
Wistar Albino Rats ◽  
Proliferating Cell

AbstractExposure of biological materials to ionizing irradiation causes accumulation of reactive oxygen species. The current study aimed to investigate whether melatonin or carnosine could provide protection against irradiation-induced small intestinal damage. Forty Wistar albino rats were divided into five groups. Melatonin, carnosine, and combination of carnosine and melatonin were injected into rats in the third, fourth, and fifth groups, respectively. Rats were injected three times every 48 hours. All groups, excluding the control group, were exposed to a dose of 8 Gray whole body gamma irradiation one hour after the second injection. It was determined that irradiation caused degenerative changes in the intestinal tissues, reduced PCNA (proliferating cell nuclear antigen) -positive cell number, and increased caspase-3- and TNF-

Clinical Update: Functional Capacity Evaluations and Disability

1998 ◽  
Vol 3 (2) ◽  
pp. 4-5
Author(s):  
Glenn Pransky
Keyword(s):  
Direct Observation ◽  
Functional Capacity ◽  
Work Capacity ◽  
Functional Capacity Evaluation ◽  
Whole Body ◽  
Validity Of Results ◽  
Job Tasks ◽  
Capacity Evaluation ◽  
Physical Abilities ◽  
The Relationship

Abstract According to the AMA Guides to the Evaluation of Permanent Impairment, a functional capacity evaluation (FCE) measures an individual's physical abilities via a set of activities in a structured setting and provides objective data about the relationship between an impairment and maximal ability to perform work activities. A key distinction between FCEs and self-reported activities of daily living is that the former involve direct observation by professional evaluators. Numerous devices can quantify the physical function of a specific part of the musculoskeletal system but do not address the performance of whole body tasks in the workplace, and these devices have not been shown to predict accurately the ability to perform all but the simplest job tasks. Information about reliability has been proposed as a way to identify magnification and malingering, but variability due to pain and poor comprehension of instructions may cause variations in assessments. Structured work capacity evaluations involve a set of activities but likely underestimate the individual's ability to do jobs that involve complex or varying activities. Job simulations involve direct observation of an individual performing actual job tasks, require a skilled and experienced evaluator, and raise questions about expense, time, objectivity and validity of results, and interpretation of results in terms of the ability to perform specific jobs. To understand the barriers to return to work, examiners must supplement FCEs with information regarding workplace environment, accommodations, and demotivators.

Tryptophan-Niacin Metabolism in Rat with Puromycin Aminonucleoside-Induced Nephrosis

2006 ◽  
Vol 76 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Yukari Egashira ◽  
Shin Nagaki ◽  
Hiroo Sanada
Keyword(s):  
Body Weight ◽  
Urinary Excretion ◽  
Enzyme Activities ◽  
Treated Group ◽  
Control Group ◽  
Puromycin Aminonucleoside ◽  
Low Level ◽  
Key Enzyme

We investigated the change of tryptophan-niacin metabolism in rats with puromycin aminonucleoside PAN-induced nephrosis, the mechanisms responsible for their change of urinary excretion of nicotinamide and its metabolites, and the role of the kidney in tryptophan-niacin conversion. PAN-treated rats were intraperitoneally injected once with a 1.0% (w/v) solution of PAN at a dose of 100 mg/kg body weight. The collection of 24-hour urine was conducted 8 days after PAN injection. Daily urinary excretion of nicotinamide and its metabolites, liver and blood NAD, and key enzyme activities of tryptophan-niacin metabolism were determined. In PAN-treated rats, the sum of urinary excretion of nicotinamide and its metabolites was significantly lower compared with controls. The kidneyα-amino-β-carboxymuconate-ε-semialdehyde decarboxylase (ACMSD) activity in the PAN-treated group was significantly decreased by 50%, compared with the control group. Although kidney ACMSD activity was reduced, the conversion of tryptophan to niacin tended to be lower in the PAN-treated rats. A decrease in urinary excretion of niacin and the conversion of tryptophan to niacin in nephrotic rats may contribute to a low level of blood tryptophan. The role of kidney ACMSD activity may be minimal concerning tryptophan-niacin conversion under this experimental condition.

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