Oxygen Cost Research Articles

Steeper or Faster? Tactical Dispositions to Minimize Oxygen Cost in Ski Mountaineering.

PurposeInvestigate the effect of speed, inclination, and use of heel elevator on the oxygen cost of vertical climbing (Cvert) in ski mountaineering.MethodsIn this study, 19 participants who were (3 women and 16 men) moderate- to well-trained recreational Norwegian ski mountaineers were involved. All participants were tested for VO2max in running, and in a ski mountaineering test on a treadmill, to assess Cvert. The test protocol consisted of 12 4 min work periods at different inclinations from 13 to 23°, with continuous VO2 measurements. After every second work period, the inclination increased by 2°, and speed was decreased accordingly. The speed reduction was based on the equation Vvert = speed · sin(α), where α represents the angle of inclination. Vvert was thus held constant for each work period (854 m·h−1). All work periods were completed twice, with and without a heel elevator. Half of the subjects started with the smallest inclination, and the other half started with the steepest inclination.ResultsThe results showed that Cvert was unchanged at all inclinations except 13°, where there was a significantly higher Cvert, at the same Vvert. Only at 13°, Cvert was higher with the use of heel elevator. There was also a significant trend indicating lower Cvert with use of heel elevator with steeper inclination.ConclusionsThere seemed to be nothing to gain by choosing detours if the inclination was 13° or less. The use of heel elevator was more advantageous, the steeper the inclination, but at 13° there was a negative effect of using heel elevator.

Fan Cooling Improves Submaximal Exercise Capacity in an Indoor Thermoneutral Environment

ABSTRACT Purpose: We compared physiological and perceptual responses to submaximal, moderate-vigorous, heart rate-based cycle ergometry with and without a fan. Methods: Sixteen recreationally active adults (25 ± 3 years; 8 men and 8 women) participated in the study. After an initial visit to assess cardiorespiratory fitness, each participant performed two 40-min training sessions on a cycle ergometer, either with or without a fan (~4 m/s), while workload was continually adjusted to elicit and maintain 70% of heart rate reserve. Workload, oxygen cost, and respiratory exchange ratio were monitored throughout, and rating of perceived exertion (RPE) and thermal sensation were recorded every 5 min. Blood lactate was recorded pre-, mid-, and post-sessions and nude body mass was obtained pre-post. Results: Greater (p < .01) mean workload (+15%) and oxygen consumption (+9%) yielded significantly greater (p < .01) energy expenditure with fan cooling (344 ± 124 kcals) compared to without fan cooling (302 ± 103 kcals). Thermal sensation, but not RPE (p = .09), was lower (p < .01) with fan cooling (3.8 ± 0.7) compared to without fan cooling (5.5 ± 0.8), and body mass loss was attenuated (p < .05) with fan cooling (−0.4 ± 0.2 kg) compared to the non-fan trial (−0.6 ± 0.3 kg). Significantly higher (p < .05) blood lactate values were observed in Fan (3.0 ± 1.9 mmol/l) vs. No Fan (2.5 ± 1.4 mmol/l) trials. Conclusions: Fan cooling during submaximal, moderate–vigorous intensity cycle ergometry significantly enhanced work capacity and energy expenditure without increasing perceived exertion. These data highlight the utility of fan cooling as a means to increase the effectiveness of indoor, heart rate-based cycle training.

The short-term development of performance and aerobic endurance following prolonged low-intensity ski trekking in Svalbard: A case study

Abstract The purpose of this case study was to examine the short-term development of performance and aerobic endurance following prolonged low-intensity ski trekking (LIST) in an Arctic region. Two male recreational athletes (aged 24 and 26 years) with high aerobic fitness performed LIST 7 ± 2 h·day−1 for 23 consecutive days, while hauling sledges (∼80 kg initially) with supplies from the north to the south of Svalbard (∼640 km). Time to exhaustion, maximal oxygen uptake (V̇O2max), lactate threshold (LT) and work economy were evaluated at pre- and post-trek. The results showed that the absolute and relative exercise intensity during LIST were ∼3.9 km·h−1 and ∼60% of maximal heart rate, respectively. Time to exhaustion during a ∼4–6 min ramp walking test, and a &gt;45 min stepwise walking test, while pulling 12.5 kg weights (simulation of ski trekking with loaded sledge), increased by 11–17% and 3–9%, respectively, following LIST. Body mass and V̇O2max relative to body mass (ml·kg−1·min−1) decreased by 5–8% and increased by 3–8%, respectively. Furthermore, the workload associated with LT and LT percentage of V̇O2max increased by 39–69% and 12–13%, respectively. No notable change in work economy was observed. The mean pace during LIST (∼3.9 km·h−1) corresponded to the treadmill walking speed (4 km·h−1) with the lowest oxygen cost (mL·kg−1·m−1) in both participants. It can be concluded that short-term prolonged LIST can improve ski trek-simulated performance and fractional utilisation of V̇O2max in recreational athletes with high aerobic fitness. Moreover, highly aerobically fit ski trekkers appear to instinctively choose the most energy-efficient pace during LIST.

An unusually high upper thermal acclimation potential for rainbow trout.

Thermal acclimation, a compensatory physiological response, is central to species survival especially during the current era of global warming. By providing the most comprehensive assessment to date for the cardiorespiratory phenotype of rainbow trout (Oncorhynchus mykiss) at six acclimation temperatures from 15°C to 25°C, we tested the hypothesis that, compared with other strains of rainbow trout, an Australian H-strain of rainbow trout has been selectively inbred to have an unusually high and broad thermal acclimation potential. Using a field setting at the breeding hatchery in Western Australia, thermal performance curves were generated for a warm-adapted H-strain by measuring growth, feed conversion efficiency, specific dynamic action, whole-animal oxygen uptake (ṀO2) during normoxia and hypoxia, the critical maximum temperature and the electrocardiographic response to acute warming. Appreciable growth and aerobic capacity were possible up to 23°C. However, growth fell off drastically at 25°C in concert with increases in the time required to digest a meal, its total oxygen cost and its peak ṀO2. The upper thermal tipping points for appetite and food conversion efficiency corresponded with a decrease in the ability to increase heart rate during warming and an increase in the cost to digest a meal. Also, comparison of upper thermal tipping points provides compelling evidence that limitations to increasing heart rate during acute warming occurred well below the critical thermal maximum (CTmax) and that the faltering ability of the heart to deliver oxygen at different acclimation temperatures is not reliably predicted by CTmax for the H-strain of rainbow trout. We, therefore, reasoned the remarkably high thermal acclimation potential revealed here for the Australian H-strain of rainbow trout reflected the existing genetic variation within the founder Californian population, which was then subjected to selective inbreeding in association with severe heat challenges. This is an encouraging discovery for those with conservation concerns for rainbow trout and other fish species. Indeed, those trying to predict the impact of global warming should more fully consider the possibility that the standing intra-specific genetic variation within a fish species could provide a high thermal acclimation potential, similar to that shown here for rainbow trout.

Effect of ground technicity on cardio-respiratory and biomechanical parameters in uphill trail running

ABSTRACT The goal of this study was to analyse the effects of ground technicity on cardio-respiratory and biomechanical responses during uphill running. Ten experienced male trail-runners ran ∼10.5 min at racing pace on two trails with different (high and low) a priori technicity levels. These two runs were replicated (same slope, velocity, and distance) indoor on a motor-driven treadmill. Oxygen uptake, minute ventilation (V̇E), heart rate as well as step frequency and medio-lateral feet accelerations (i.e. objective indices of uneven terrain running patterns adjustments) were continuously measured throughout all sessions. Rating of perceived exertion (RPE) and perceived technicity were assessed at the end of each bout. Oxygen cost of running (O2Cr) (+10.5%; p < 0.001), V̇E (+21%; p < 0.004) and the range and variability of feet medio-lateral accelerations (+116% and +134%, respectively; p < 0.001), were significantly greater when running on trail compared to the treadmill, regardless of the a priori technicity level. Despite perceived technicity being lower on treadmill (p < 0.001), RPE was not different between trail and treadmill runs (p < 0.68). It is concluded that running uphill on a trail vs. a treadmill significantly elevates both O2Cr and magnitude/variability of feet medio-lateral accelerations but no difference could be identified between trails of different a priori technicities. These results strengthen the need for trainers and race organisers to consider terrain technicity per se as a challenging cardio-respiratory and biomechanical component in uphill trail running. Highlights Ten experienced male trail-runners ran ∼10.5 min at racing pace on two trails with different a priori technicity levels. The two runs were replicated (same slope, velocity, and distance) indoor on a motor-driven treadmill. Oxygen cost of running (O2Cr), minute ventilation (V̇E) as well as medio-lateral feet accelerations (i.e. objective indices of uneven terrain running patterns adjustments) were continuously measured throughout all sessions. Rating of perceived exertion (RPE) and perceived technicity were assessed at the end of each bout. O2Cr (+10.5%; p < 0.001), V̇E (+21%; p < 0.004) and the magnitude and variability of feet medio-lateral accelerations (+116% and +134%, respectively; p < 0.001) were significantly greater when running on trail compared to treadmill, regardless of the a priori technicity level. Despite O2Cr being different between trail and treadmill runs, RPE was not. Thus, running uphill on a trail vs. on a treadmill significantly elevates both O2Cr and magnitude/variability of feet medio-lateral accelerations but no difference could be identified between trails of different a priori technicities.

The root of the matter: nitrate-rich beetroot juice reduces skeletal muscle O2 uptake during exercise.

The root of the matter: nitrate-rich beetroot juice reduces skeletal muscle O2 uptake during exercise.

Comparative Analysis of Actual Cost and INA CBG Rate in Diabetic Gangrene Inpatients

Background: Diabetic gangrene is a complication of diabetes mellitus that imposes a substantial financial burden on patients and their families as well as the health care system. Objective: To determine the total cost of disease, and the difference between real cost and INA CBG rate for diabetic gangrene inpatients from January - December 2017 at Universitas Airlangga Hospital, Surabaya Methods: The study was conducted retrospectively by using a total sampling method. The perspective used was the hospital perspective. This study's direct medical costs were laboratory, drug and consumable medical device costs, medical equipment rental, radiology examination, red cross, oxygen, service, and room costs. Data analysis was performed using an independent samples t-test. Results: The results showed that 148 patients met the inclusion criteria. The total real cost of diabetic gangrene inpatients at Universitas Airlangga Hospital in 2017 was IDR 1,339,949,381, and the total INA CBG rate for inpatients with diabetic gangrene was IDR 1,365,047,500. The difference was (p = 0.000) between real cost and INA CBG rate. Conclusion: There is a difference between the actual cost and the INA CBG rate for diabetic gangrene inpatients.

Highly Cushioned Shoes Improve Running Performance in Both the Absence and Presence of Muscle Damage.

ABSTRACTPurposeWe tested the hypotheses that a highly cushioned running shoe (HCS) would 1) improve incremental exercise performance and reduce the oxygen cost (Oc) of submaximal running, and 2) attenuate the deterioration in Oc elicited by muscle damage consequent to a downhill run.MethodsThirty-two recreationally active participants completed an incremental treadmill test in an HCS and a control running shoe (CON) for the determination of Oc and maximal performance. Subsequently, participants were pair matched and randomly assigned to one of the two footwear conditions to perform a moderate-intensity running bout before and 48 h after a 30-min downhill run designed to elicit muscle damage.ResultsIncremental treadmill test performance was improved (+5.7%; +1:16 min:ss; P < 0.01) in the HCS when assessed in the nondamaged state, relative to CON. This coincided with a significantly lower Oc (−3.2%; −6 mL·kg−1·km−1; P < 0.001) at a range of running speeds and an increase in the speed corresponding to 3 mM blood lactate (+3.2%; +0.4 km·h−1; P < 0.05). As anticipated, the downhill run resulted in significant changes in biochemical, histological, and perceptual markers of muscle damage, and a significant increase in Oc (+5.2%; 10.1 mL·kg−1·km−1) was observed 48 h post. In the presence of muscle damage, Oc was significantly lower in HCS (−4.6%; −10 mL·kg−1·km−1) compared with CON.ConclusionsThese results indicate that HCS improved incremental exercise performance and Oc in the absence of muscle damage and show, for the first time, that despite worsening of Oc consequent to muscle damage, improved Oc in HCS is maintained.

Development of a gas-permeable bag photobioreactor for energy-efficient oxygen removal from algal culture

Closed photobioreactors are ideal for the production of high-purity and high-value microalgal and cyanobacterial products. However, dissolved oxygen accumulation in closed reactors is detrimental to the growth. Conventional aeration for oxygen removal comprises up to 40% of the total culture cost, and energy-efficient dissolved oxygen removal is demanded. In this study, a novel gas-permeable bag photobioreactor was developed by the incorporation of a gas-permeable film. A hydrophobic microporous film was the most effective for both oxygen permeability and cost compared to silicone or fluororesin. The microporous film was placed on the backside of the reactor as an irradiation reflector. In a culture of Euhalothece sp., less than half of the steady-state dissolved oxygen concentration was demonstrated in the gas-permeable reactor than a non-permeable reactor. The gas-permeable reactor exhibited an oxygen transfer coefficient of 0.084 min−1 under continuous mixing, which is high enough to maintain approximately 300% dissolved oxygen concentration with 58 mg L−1 h−1 biomass productivity without aeration (equivalent to 1.4 g L−1 d−1 under 24-h light). The estimated energy requirement for the gas-permeable reactor can be less than 1% of the aerated reactor of the same size. These results suggested the effectiveness of the gas-permeable reactor for energy-efficient algal mass culture.

The Incremental Shuttle Walk Test

The Incremental Shuttle Walk Test

Application of Leg, Vertical, and Joint Stiffness in Running Performance: A Literature Overview.

Stiffness, the resistance to deformation due to force, has been used to model the way in which the lower body responds to landing during cyclic motions such as running and jumping. Vertical, leg, and joint stiffness provide a useful model for investigating the store and release of potential elastic energy via the musculotendinous unit in the stretch-shortening cycle and may provide insight into sport performance. This review is aimed at assessing the effect of vertical, leg, and joint stiffness on running performance as such an investigation may provide greater insight into performance during this common form of locomotion. PubMed and SPORTDiscus databases were searched resulting in 92 publications on vertical, leg, and joint stiffness and running performance. Vertical stiffness increases with running velocity and stride frequency. Higher vertical stiffness differentiated elite runners from lower-performing athletes and was also associated with a lower oxygen cost. In contrast, leg stiffness remains relatively constant with increasing velocity and is not strongly related to the aerobic demand and fatigue. Hip and knee joint stiffness are reported to increase with velocity, and a lower ankle and higher knee joint stiffness are linked to a lower oxygen cost of running; however, no relationship with performance has yet been investigated. Theoretically, there is a desired “leg-spring” stiffness value at which potential elastic energy return is maximised and this is specific to the individual. It appears that higher “leg-spring” stiffness is desirable for running performance; however, more research is needed to investigate the relationship of all three lower limb joint springs as the hip joint is often neglected. There is still no clear answer how training could affect mechanical stiffness during running. Studies including muscle activation and separate analyses of local tissues (tendons) are needed to investigate mechanical stiffness as a global variable associated with sports performance.

Energetics of walking in individuals with cerebral palsy and typical development, across severity and age: A systematic review and meta-analysis.

Individuals with cerebral palsy (CP) report physical fatigue as a main cause of limitation, deterioration and eventually cessation of their walking ability. A consequence of higher level of fatigue in individuals with CP leads to a less efficient and long-distance walking ability. This systematic review investigates the difference in 1) walking energy expenditure between individuals with CP and age-matched typically developing (TD) individuals; and 2) energetics of walking across Gross Motor Function Classification System (GMFCS) levels and age. Five electronic databases (PubMed, Web of Science, CINAHL, ScienceDirect and Scopus) were searched using search terms related to CP and energetics of walking. Forty-one studies met inclusion criteria. Thirty-one studies compared energy expenditure between CP and age-matched controls. Twelve studies correlated energy expenditure and oxygen cost across GMFCS levels. Three studies investigated the walking efficiency across different ages or over a time period. A significant increase of energy expenditure and oxygen cost was found in individuals with CP compared to TD age-matched individuals, with a strong relationship across GMFCS levels. Despite significant differences between individuals with CP compared to TD peers, variability in methods and testing protocols may play a confounding role. Analysis suggests oxygen cost being the preferred/unbiased physiological parameter to assess walking efficacy in CP. To date, there is a knowledge gap on age-related changes of walking efficiency across GMFCS levels and wider span of age ranges. Further systematic research looking at longitudinal age-related changes of energetics of walking in this population is warranted.

Longitudinal changes in energy cost during walking in boys with Duchenne Muscular Dystrophy (DMD).

In boys with DMD, muscle weakness progresses in a proximal to distal pattern, leading to compensatory gait strategies, including hyperlordosis and equinus, that increase energy cost and accelerate the loss of walking capacity. The purpose of this study was to determine the changes in the energy cost of walking that occur with disease progression and to determine the optimal normalization scheme for the longitudinal assessment of the energy cost of walking in boys with DMD. Energy cost was assessed with the COSMED K4b2. Three normalization schemes were examined: gross energy cost (EC), net non-dimensional oxygen cost (NNcost) and speed-matched control energy cost (SMC-EC). Nonlinear mixed modeling procedures determined the rate of change with age. Linear regression was used to asses the relationship between each normalization scheme and age and body height. 74 boys with DMD were assessed for the energy cost of walking. Velocity decreased at a significant rate (-.00245/month, p = .03) across time; (Fig. 2), while gross EC (.003248/month, p = 0.0026), NNcost (.006155/month, p < 0.0001) and SMC-EC (.001690/month, p = 0.03) all increased significantly. Age and height were significantly associated with NNcost and SMC-EC. The sensitivity of NNcost and SMC-EC to age over time were similar, while SMC-EC was less sensitive to changes in height over time than NNcost. In contrast to able-bodied peers, boys with DMD decrease their velocity while all walking energy cost measures increased over time. Both SMC-EC and NNcost proved appropriate normalization schemes for boys with DMD. Compared to gross EC, both NNcost and SMC-EC were less sensitive to changes in age over time, while SMC-EC was less sensitive to changes in height than NNcost. Therefore, both NNCost and SMC-EC are suggested normalization schemes for the longitudinal assessment of energy cost in boys with DMD.

Which method should be chosen to estimate the oxygen cost of walking in post-stroke individuals?

The oxygen cost of walking (Cw) represents the energy expenditure involved in walking, which is a major concern when quantifying physical activity in stroke. Recent studies have reported that Cw may be estimated accurately with a prediction equation using the self-self-selected walking speed (Sfree). To evaluate the validity of Cw estimates according to different modalities of Sfree measurements (10-m walking test, 6-minute walking test, GaitRite system). Twenty-one stroke individuals in subacute phase who were able to walk without human aid were included. Cw was estimated from the walking speed measured during a 10-m walking test, a 6-minute walking test and a recording on a GaitRite system. The values of the Cw estimates were compared to those measured by a respiratory gas exchange analyzer (Metamax3b). The findings showed that there is no significant difference between the Cw measured by Metamax3b and the Cw estimates regardless of the modalities used to measure Sfree (Fvalue = 0.02; pvalue = 0.99). The mean bias between Cw measured by the Metamax3b and those estimated using the different Sfree measurement modalities was less than 2.5 % of the mean Cw value. Test retest reliability was excellent with an intraclass correlation coefficient higher than 0.95. in stroke survivors who are able to walk independently without human aid, the use of a 10-m walking test, a 6-minute walking test or a GaitRite recording can be considered validated for estimating Cw.

Continuous Monitoring of the Thermoregulatory Response in Endurance Horses and Trotter Horses During Field Exercise: Baselining for Future Hot Weather Studies.

Establishing proper policies regarding the recognition and prevention of equine heat stress becomes increasingly important, especially in the face of global warming. To assist this, a detailed view of the variability of equine thermoregulation during field exercise and recovery is essential. 13 endurance horses and 12 trotter horses were equipped with continuous monitoring devices [gastrointestinal (GI) pill, heartrate (HR) monitor, and global positioning system] and monitored under cool weather conditions during four endurance rides over a total of 80 km (40 km loops) and intense trotter track-based exercise over 1,540 m. Recordings included GI temperature (Tc), speed, HR and pre- and post-exercise blood values. A temperature time profile curve of Tc was constructed, and a net area under the curve was calculated using the trapezoidal method. Metabolic heat production and oxygen cost of transport were also calculated in endurance horses. Maximum Tc was compared using an independent samples t-test. Endurance horses (mean speed 14.1 ± 1.7 km h–1) reached mean maximum Tc (39.0 ± 0.4°C; 2 × 40 km in 8 horses) during exercise at 75% of completion of Tc exercise and Tc returned to baseline within 60 min into recovery. However, the mean Tc was still 38.8 ± 0.4°C at a HR of 60 bpm which currently governs “fit to continue” competition decisions. Trotters (40.0 ± 2.9 km h–1) reached a comparable mean max Tc (38.8 ± 0.5°C; 12 horses) always during recovery. In 30% of trotters, Tc was still >39°C at the end of recovery (40 ± 32 min). The study shows that horses are individuals and thermoregulation monitoring should reflect this, no matter what type of exercise is performed. Caution is advised when using HR cut-off values to monitor thermal welfare in horses since we have demonstrated how Tc can peak quite some time after finishing exercise. These findings have implications for training and management of performance horses to safeguard equine welfare and to maximize performance.

Effects of neuromuscular electrical stimulation on torque and performance in recreational distance runners: A randomized controlled trial

IntroductionNeuromuscular electrical stimulation (NMES) is used by athletes to improve muscle performance. However, evidence on the use of NMES in long distance runners is scarce. As such, this study aimed to evaluate the effects of NMES on the muscle torque and sports performance of long-distance recreational runners. MethodsThis was a blinded randomized controlled trial. Data from 30 volunteers were analyzed. Participants were randomly allocated to an experimental (n = 15) or control group (n = 15). The experimental group was submitted to running training (RT) and a strengthening protocol with NMES (1 kHz, modulated in 2 ms bursts, 50 Hz modulated burst frequency and 10% duty cycle, 15 min totaling 18 contractions per sessions) for 6 weeks, with 3 sessions per week, while controls were submitted to RT alone. The following variables were analyzed: peak isometric (ISO), concentric (CON), and eccentric (ECC) torque of the quadriceps muscle in voluntary contractions, ventilatory anaerobic thresholds (VATs), maximal oxygen uptake (VO2max), and oxygen cost of transport (OCT). ResultsThe NMES group obtained higher values of ISO, 21.04% (p = 0.001), CON, 21.97% (p = 0.001) and ECC, 18.74% (p = 0.001) peak torque and VAT1, 9.56% (p = 0.001), as well as a statistically significant improvement in oxygen cost of transport at VAT1 when compared to controls (p = 0.001). ConclusionNMES was effective in improving peak isometric, concentric and eccentric quadriceps muscle torque, in addition to being an interesting resource for enhancing sports performance in long-distance recreational runners and future clinical trials should be performed to compare the use of NMES to different forms of training over longer training periods.

Moderate-intensity exercise with blood flow restriction on cardiopulmonary kinetics and efficiency during a subsequent high-intensity exercise in young women: A cross-sectional study.

Blood flow restriction (BFR) training applied prior to a subsequent exercise has been used as a method to induce changes in oxygen uptake pulmonary kinetics (O2P) and exercise performance. However, the effects of a moderate-intensity training associated with BFR on a subsequent high-intensity exercise on O2P and cardiac output (QT) kinetics, exercise tolerance, and efficiency remain unknown.This prospective physiologic study was performed at the Exercise Physiology Lab, University of Brasilia. Ten healthy females (mean ± SD values: age = 21.3 ± 2.2 years; height = 1.6 ± 0.07 m, and weight = 55.6 ± 8.8 kg) underwent moderate-intensity training associated with or without BFR for 6 minutes prior to a maximal high-intensity exercise bout. O2P, heart rate, and QT kinetics and gross efficiency were obtained during the high-intensity constant workload exercise test.No differences were observed in O2P, heart rate, and QT kinetics in the subsequent high-intensity exercise following BFR training. However, exercise tolerance and gross efficiency were significantly greater after BFR (220 ± 45 vs 136 ± 30 seconds; P < .05, and 32.8 ± 6.3 vs 27.1 ± 5.4%; P < .05, respectively), which also resulted in lower oxygen cost (1382 ± 227 vs 1695 ± 305 mL min–1).We concluded that moderate-intensity BFR training implemented prior to a high-intensity protocol did not accelerate subsequent O2P and QT kinetics, but it has the potential to improve both exercise tolerance and work efficiency at high workloads.

Evaluation of sex-based differences in airway size and the physiological implications.

Recent evidence suggests healthy females have significantly smaller central conducting airways than males when matched for either height or lung volume during analysis. This anatomical sex-based difference could impact the integrative response to exercise. Our review critically evaluates the literature on direct and indirect techniques to measure central conducting airway size and their limitations. We present multiple sources highlighting the difference between male and female central conducting airway size in both pediatric and adult populations. Following the discussion of measurement techniques and results, we discuss the functional implications of these differences in central conducting airway size, including work of breathing, oxygen cost of breathing, and how these impacts will continue into elderly populations. We then discuss a range of topics for the future direction of airway differences and the benefits they could provide to both healthy and diseased populations. Specially, these sex-differences in central conducting airway size could result in different aerosol deposition or how lung disease manifests. Finally, we detail emerging techniques that uniquely allow for high-resolution imaging to be paired with detailed physiological measures.

Sex-Based Differences in Oxygen Cost of Walking and Energy Equivalents in Minimally Disabled Individuals With Multiple Sclerosis and Controls.

Elevated oxygen cost of walking and energy equivalents are reported for highly and moderately disabled individuals with multiple sclerosis (MS). However, less is known about minimally impaired individuals. Moreover, no sex-based data on the metabolic rates of individuals with MS are available. In this cross-sectional study, the metabolic rates and temporospatial parameters of gait during overground walking in minimally disabled individuals with MS versus matched controls were quantified and whether sex-based differences occur was examined. Sixty-nine minimally impaired adults with MS (37, relapsing-remitting MS [RRMS]; 32, clinically isolated syndrome [CIS]) and 25 matched controls completed two 6-minute walking bouts at comfortable and fast speeds. The oxygen cost of walking, energy equivalents, and respiratory exchange ratio were recorded through breath-by-breath open-circuit spirometry. Gait analysis was performed via a portable electronic walkway. At comfortable but not at fast speed, men with RRMS showed higher oxygen cost of walking than men with CIS (+17.9%, P = .04) and male controls (+21.3%, P = .03). In the RRMS group, men showed higher oxygen cost of walking (+19.2%, P = .04) and energy equivalents (+19.2%, P = .02) than women. Elevated oxygen cost of walking and energy equivalents in men were paralleled by significantly larger base of support and step time asymmetry during walking. Metabolic demands are elevated while walking in minimally disabled individuals with RRMS. Furthermore, higher energy demands occur in men, probably due to increased step symmetry and base of support. Clinicians are advised to follow energy expenditure metrics collected while walking because they can indicate a decrease in fitness, even in the early phase of MS.

Cost implication of CPAP use in low resource settings, surmounting the oxygen administration challenge

Purpose Newborn respiratory support using Bubble Continuous positive airway pressure (bCPAP) has become acceptable in Nigeria as many centers are increasingly reporting its usefulness. There is increasing access to CPAP devices although the use of 100% oxygen for bCPAP administration is on the rise as oxygen/air blenders are not commonly available or insufficient. The cost of oxygen has become a significant contributor to hospital bills. The oxygen concentrator driven bCPAP device with blending capacity is expected to save lives and reduce cost of care. Objective To compare the cost saving benefit of the use of oxygen concentrator bCPAP devices for CPAP administration to oxygen based devices in a resource limited setting. Methods This prospective cross sectional study was done between February and December 2019. The oxygen use by CPAP devices-Improvised (IbCPAP), Fisher and Paykel and T-piece were quantified, costed, documented and compared with the same duration of use of concentrator CPAP-Diamedica. Results CPAP services was accessed by 357 babies, 154 males and 203 females of GA range from 22 to 42 weeks and Birthweights range from 264 to 4400 grams. The main indication for CPAP was respiratory distress syndrome 201(56.3%). Oxygen supply were by oxygen pipeline 250 (70%), cylinders 39 (10.9%), concentrator CPAP 44 (12.3%) mixed source 24 (6.7%). Mean duration on the CPAP devices was 5.4 days, mean cost ₦37,645 ($104) or ₦6,971 ($20)/day, highest with IbCPAP, non-existent with concentrator bCPAP. Conclusion The high running cost implication of CPAP use in low resource settings could deter transitioning to quality devices hence the need for non-oxygen dependent devices.