Pulmonary function is lower after a severe burn injury, which could influence ventilatory responses during exercise. It is unclear whether exercise training improves pulmonary function or ventilatory ...responses during exercise in adults with well-healed burn injuries. Therefore, we tested the hypothesis that exercise training improves pulmonary function and ventilatory responses during exercise in adults with well-healed burn injuries.
Thirty-nine adults (28 with well-healed burn injuries and 11 non-burn-injured controls) completed 6 months of unsupervised, progressive exercise training including endurance, resistance, and high-intensity interval components. Before and after exercise training, we performed comprehensive pulmonary function testing and measured ventilatory responses during cycling exercise. We compared variables using two-way ANOVA (group-time; i.e., preexercise/postexercise training (repeated factor)).
Exercise training did not increase percent predicted spirometry, lung diffusing capacity, or airway resistance measures (time: P ≥ 0.14 for all variables). However, exercise training reduced minute ventilation ( V̇E ; time: P ≤ 0.05 for 50 and 75 W) and the ventilatory equivalent for oxygen ( V̇E /V̇O 2 ; time: P < 0.001 for 75 W) during fixed-load exercise for both groups. The ventilatory equivalent for carbon dioxide ( V̇E /V̇CO 2 ) during exercise at 75 W was reduced after exercise training (time: P = 0.04). The percentage of age-predicted maximum heart rate at the ventilatory threshold was lower in adults with well-healed burn injuries before ( P = 0.002), but not after ( P = 0.22), exercise training. Lastly, exercise training increased V̇E and reduced V̇E /V̇O 2 during maximal exercise (time: P = 0.005 for both variables).
These novel findings demonstrate that exercise training can improve ventilatory responses during exercise in adults with well-healed burn injuries.
Ventilatory constraints are common during exercise in children, but the effects of obesity and sex are unclear. The purpose of this study was to investigate the effects of obesity and sex on ...ventilatory constraints (i.e., expiratory flow limitation (EFL) and dynamic hyperinflation) during a maximal exercise test in children.
Thirty-four 8-12-year-old children without obesity (18 females) and 54 with obesity (23 females) completed pulmonary function testing and maximal cardiopulmonary exercise tests. EFL was calculated as the overlap between tidal flow-volume loops during exercise and maximal expiratory flow-volume loops. Dynamic hyperinflation was calculated as the change in inspiratory capacity from rest to exercise.
Maximal minute ventilation was not different between children with and without obesity. Average end-inspiratory lung volumes (EILV) and end-expiratory lung volumes (EELV) were significantly lower during exercise in children with obesity (EILV: 68.8 ± 0.7%TLC; EELV: 41.2 ± 0.5%TLC) compared with children without obesity (EILV: 73.7 ± 0.8%TLC; EELV: 44.8 ± 0.6%TLC; P < 0.001). Throughout exercise, children with obesity experienced more EFL and dynamic hyperinflation compared with those without obesity (P < 0.001). Also, males experienced more EFL and dynamic hyperinflation throughout exercise compared with females (P < 0.001). At maximal exercise, the prevalence of EFL was similar in males with and without obesity, however the prevalence of EFL in females was significantly different with 57% of females with obesity experiencing EFL compared with 17% of females without obesity (P < 0.05). At maximal exercise, 44% of children with obesity experienced dynamic hyperinflation compared with 12% of children without obesity (P = 0.002).
Obesity in children increases the risk of developing mechanical ventilatory constraints such as dynamic hyperinflation and EFL. Sex differences were apparent with males experiencing more ventilatory constraints compared with females.
Little is known about whether body composition changes differently between children with and without obesity following 1 year of nonintervention. Therefore, we investigated body composition in early ...pubescent children (8-12 yr) with and without obesity before and after a period of 1 year of nonintervention. Early pubescent children (8-12 yr; Tanner stage ≤ 3) with (body mass index, BMI ≥ 95th percentile) and without obesity (15th < BMI < 85th percentile) were recruited. At baseline, 88 children (
= 25 without obesity) completed dual-energy X-ray absorptiometry imaging (DXA) for body composition measurements %body fat, fat mass, fat-free mass (FFM). One year later, 47 participants (
= 15 without obesity) returned for repeat testing. The children without obesity were older (11.0 ± 1.0 vs. 10.0 ± 1.2 yr; means ± SD) (
= 0.013). There was no group difference in height, and both groups increased in height similarly after 1 year (147.7 ± 8.9 to 154.5 ± 9.2 cm without vs. 145.6 ± 5.8 to 152.5 ± 5.9 cm with obesity) (
< 0.001). Weight was greater (
< 0.001) in children with obesity at baseline as was the increase in weight after 1 yr (9.25 vs. 5.82 kg) (interaction,
= 0.005). Fat mass increased by 4.4 kg in children with obesity and by 1.1 kg in children without obesity (interaction,
< 0.001). However, there was no difference in fat-free mass between those with and without obesity at baseline (29.9 ± 5.9 vs. 31.6 ± 4.8 kg) (
= 0.206) with both groups increasing similarly over 1 year (gain of 4.87 vs. 4.85 kg with and without obesity, respectively). Without intervention, the increase in fat mass is four times greater in children with obesity after 1 year as compared with children without obesity.
Little is known about changes in body composition in children with and without obesity following 1 year of nonintervention. We report that without intervention, fat mass gain is significantly greater in children with obesity after 1 year compared with those without obesity. Body mass index (BMI) and %body fat measurements after 1 year yielded no significant increase suggesting that BMI and %fat alone are not suitable measures for tracking changes in adiposity among children.
Background
In children, obesity typically reduces functional residual capacity (FRC), which reduces airway caliber and increases airway resistance. Whether these obesity‐related changes in ...respiratory function can alter bronchodilator responsiveness is unknown.
Objective
To investigate bronchodilator responsiveness in nonasthmatic children with and without obesity.
Methods
Seventy nonasthmatic children, 8−12 years old, without (n = 19) and with (n = 51) obesity, completed spirometry, impulse oscillometry, and airway resistance measurements through plethysmography pre/post 360 µg of inhaled albuterol. FRC was assessed pre albuterol. A two‐way analysis of variance determined the effects of obesity (group) and inhaled albuterol (pre−post) on outcome measures.
Results
FRC (%total lung capacity) was 16% lower in children with obesity compared with those without obesity. There was no significant group by pre−post albuterol interaction on any outcome variables. Albuterol inhalation reduced total, central and peripheral airway resistance and increased airway reactance (i.e., less negative) to a similar degree in children with and without obesity. In children with obesity, airway resistance was increased whether measured by impulse oscillometry or plethysmography. However, once airway resistance was adjusted for lung volumes (i.e., specific airway resistance or sRaw), there were no differences between children with and without obesity. In addition, significant but moderate associations were detected between chest mass and FRC (r = −0.566; p < 0.001), FRC and total airway resistance (i.e., Raw; r = −0.445; p < 0.001).
Conclusions
In nonasthmatic early pubescent children, obesity increases total, central, and peripheral respiratory system resistance. However, the added respiratory system resistance and low lung volume breathing with obesity are not sufficient to reduce bronchodilator responsiveness.
In humans, elevated body temperatures can markedly increase the ventilatory response to exercise. However, the impact of changing the effective body surface area (BSA) for sweat evaporation (BSA
) on ...such responses is unclear. Ten healthy adults (9 males, 1 female) performed eight exercise trials cycling at 6 W/kg of metabolic heat production for 60 min. Four conditions were used where BSA
corresponded to 100%, 80%, 60%, and 40% of BSA using vapor-impermeable material. Four trials (one at each BSA
) were performed at 25°C air temperature, and four trials (one at each BSA
) at 40°C air temperature, each with 20% humidity. The slope of the relation between minute ventilation and carbon dioxide elimination (V̇
/V̇co
slope) assessed the ventilatory response. At 25°C, the V̇
/V̇co
slope was elevated by 1.9 and 2.6 units when decreasing BSA
from 100 to 80 and to 40% (
= 0.033 and 0.004, respectively). At 40°C, V̇
/V̇co
slope was elevated by 3.3 and 4.7 units, when decreasing BSA
from 100 to 60 and to 40% (
= 0.016 and
< 0.001, respectively). Linear regression analyses using group average data from each condition demonstrated that end-exercise mean body temperature (integration of core and mean skin temperature) was better associated with the end-exercise ventilatory response, compared with core temperature alone. Overall, we show that impeding regional sweat evaporation increases the ventilatory response to exercise in temperate and hot environmental conditions, and the effect is mediated primarily by increases in mean body temperature.
Exercise in the heat increases the slope of the relation between minute ventilation and carbon dioxide elimination (V̇
/V̇co
slope) in young healthy adults. An indispensable role for skin temperature in modulating the ventilatory response to exercise is noted, contradicting common belief that internal/core temperature acts independently as a controller of ventilation during hyperthermia.
PURPOSEThoracic gas compression and exercise-induced bronchodilation can influence the assessment of expiratory flow limitation (EFL) during cardiopulmonary exercise tests. The purpose of this study ...was to examine the effect of thoracic gas compression and exercise-induced bronchodilation on the assessment of EFL in children with and without obesity.
METHODSForty children (10.7 ± 1.0 yr; 27 obese; 15 with EFL) completed pulmonary function tests and incremental exercise tests. Inspiratory capacity maneuvers were performed during the incremental exercise test for the placement of tidal flow volume loops within the maximal expiratory flow volume (MEFV) loops, and EFL was calculated as the overlap between the tidal and the MEFV loops. MEFV loops were plotted with volume measured at the lung using plethysmography (MEFVp), with volume measured at the mouth using spirometry concurrent with measurements in the plethysmograph (MEFVm), and from spirometry before (MEFVpre) and after (MEFVpost) the incremental exercise test. Only the MEFVp loops were corrected for thoracic gas compression.
RESULTSNot correcting for thoracic gas compression resulted in incorrect diagnosis of EFL in 23% of children at peak exercise. EFL was 26% ± 15% VT higher for MEFVm compared with MEFVp (P < 0.001), with no differences between children with and without obesity (P = 0.833). The difference in EFL estimation using MEFVpre (37% ± 30% VT) and MEFVpost (31% ± 26% VT) did not reach statistical significance (P = 0.346).
CONCLUSIONSNot correcting the MEFV loops for thoracic gas compression leads to the overdiagnosis and overestimation of EFL. Because most commercially available metabolic measurement systems do not correct for thoracic gas compression during spirometry, there may be a significant overdiagnosis of EFL in cardiopulmonary exercise testing. Therefore, clinicians must exercise caution while interpreting EFL when the MEFV loop is derived through spirometry.
Dysanapsis in men and women with obesity Stickford, Jonathon L.; Wilhite, Daniel P.; Bhammar, Dharini M. ...
Journal of applied physiology (1985),
08/2021, Letnik:
131, Številka:
2
Journal Article
Recenzirano
Odprti dostop
It is unclear whether obesity in combination with sex influences the dysanapsis ratio (DR). These data indicate that DR is unaltered in adults with obesity and is greater in women than in men but ...similar between sexes when matched for lung volume. We also report a significant difference between predicted and measured static recoil pressure. Thus, we caution against predicting static recoil pressure in the calculation of DR.
Obesity alters chest wall mechanics, reduces lung volumes, and increases airway resistance. In addition, the luminal area of the larger conducting airways is smaller in women than in men when matched for lung size. We examined whether differences in pulmonary mechanics with obesity and sex were associated with the dysanapsis ratio (DR), an estimate of airway size when the expiratory flow is maximal, in men and women with and without obesity. In addition, we examined the ability to estimate DR using predicted versus measured static recoil pressure at 50% forced vital capacity (FVC; Pst
50FVC
). Participants completed pulmonary function testing and measurements of pulmonary mechanics. Flow, volume, and transpulmonary pressure were recorded while completing forced vital capacity (FVC) maneuvers in a body plethysmograph. Static compliance curves were collected using the occlusion technique. DR was calculated using measured values of forced midexpiratory flow and Pst
50FVC
. DR was also calculated using Pst predicted from previously reported data. There was no significant group (lean vs. obese) by sex interaction or main effect of group on DR. However, women displayed significantly larger DR compared with men. Predicted Pst
50FVC
was significantly greater than measured Pst
50FVC
. DR calculated from measured Pst was significantly greater than when using predicted Pst. In conclusion, although obesity does not appear to alter airway size, women may have larger airways compared with men when midexpiratory flow is maximal. In addition, DR estimated using predicted Pst should be used with caution.
NEW & NOTEWORTHY It is unclear whether obesity in combination with sex influences the dysanapsis ratio (DR). These data indicate that DR is unaltered in adults with obesity and is greater in women than in men but similar between sexes when matched for lung volume. We also report a significant difference between predicted and measured static recoil pressure. Thus, we caution against predicting static recoil pressure in the calculation of DR.
Constantini, Keren, Daniel P. Wilhite, and Robert F. Chapman. A clinician guide to altitude training for optimal endurance exercise performance at sea level. High Alt Med Biol. 18:93-101, 2017.-For ...well over 50 years, endurance athletes have been utilizing altitude training in an effort to enhance performance in sea level competition. This brief review will offer the clinician a series of evidence-based best-practice guidelines on prealtitude and altitude training considerations, which can ultimately maximize performance improvement outcomes.
•The exercise ventilatory response is similar between obese and nonobese children.•The exercise ventilatory response is higher in girls compared with boys.•Sex-differences were eliminated with the ...removal of external dead space.•Dead space should be removed when assessing the exercise ventilatory response.
We compared the exercise ventilatory response (slope of the ventilation, V̇E and carbon dioxide production, V̇CO2 relationship) in boys and girls with and without obesity. 46 children with obesity (BMI percentile: 97.7 ± 1.4) and 27 children without obesity (BMI percentile: 55.1 ± 22.2) were included and divided into groups by sex (with obesity: 17 girls and 29 boys; without obesity: 13 girls and 14 boys). A 6 min constant load cycling test at 45 % of peak work rate was performed. The V̇E/V̇CO2 slope was similar (p = 0.67) between children with (32.7 ± 4.3) and without (32.2 ± 6.1) obesity; however, it was higher (p = 0.02) in girls (35.4 ± 5.6) than boys (32.6 ± 4.9). We also examined a corrected V̇E/V̇CO2 slope for the effects of mechanical dead space (VDM), by subtracting V̇DM from V̇E (V̇Ecorr/V̇CO2 slope). The V̇Ecorr/V̇CO2 slope remained similar (p = 0.37) between children with (26.8 ± 3.2) and without obesity (26.1 ± 3.1); however, no sex differences were observed (p = 0.13). Therefore, VDM should be accounted for before evaluating the V̇E/V̇CO2 slope, particularly when making between-sex comparisons.
•Changes in RPB during exercise or EVH are in linear proportion to changes in V̇E.•RPB at a given V̇E is elevated in obese women with vs. without dyspnea on exertion.•Obese women with dyspnea on ...exertion experience increased perception for a given V̇E.
Temporal responses of ratings of perceived breathlessness (RBP) during constant-load and incremental exercise, and during voluntary hyperpnea (EVH) were examined in women with obesity. Following 6 min of constant-load (60W) cycling, 34 women rated RPB≥4 (+DOE) and 22 women rated RPB≤2 (–DOE). Both groups completed an incremental cycling test and an EVH test at 40 and 60L/min; RPB was assessed each minute of incremental cycling and at the end of each EVH trial. RPB increased with ventilation during constant-load (+DOE: R2=0.86; –DOE: R2=0.82) and incremental (+DOE: R2=0.91; –DOE: R2=0.92) exercise, but + DOE had a greater y-intercept than –DOE (60W: -0.16±1.53 vs. -0.73±0.55; incremental: -0.50±1.40 vs. -1.71±0.84). Despite matching ventilation, RPB was greater in + DOE at baseline (0.97±1.14 vs. 0.14±0.28), 40L/min (2.50±1.43 vs. 0.98±0.91), and 60L/min (3.94±2.19 vs. 2.07±1.32) during EVH. These findings show that despite linear associations between RPB and ventilation during exercise and voluntary hyperpnea, breathlessness perception at a given ventilatory demand is heightened in +DOE compared with –DOE.
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