The effects of antioxidant vitamin supplementation on expiratory flow rates at rest and during exercise

Journal of Applied Physiology

Cross

Iterson

et al. 2018

Self Cite

It is unknown whether the greater total work of breathing (WOB) with aging is due to greater elastic and/or resistive WOB. We hypothesized that older compared with younger adults would exhibit a greater total WOB at matched ventilations (V̇e) during graded exercise, secondary to greater inspiratory resistive and elastic as well as expiratory resistive WOB. Older (OA: 60 ± 8 yr; n = 9) and younger (YA: 38 ± 7 yr; n = 9) adults performed an incremental cycling test to volitional fatigue. Esophageal pressure, inspiratory (IRV) and expiratory reserve volumes (ERV), expiratory flow limitation (EFL), and ventilatory variables were measured at matched V̇e (i.e., 25, 50, and 75 l/min) during exercise. The inspiratory resistive and elastic as well as expiratory resistive WOB were quantified using the Otis method. At V̇e of 75 l/min, older adults had greater %EFL and larger tidal volumes to inspiratory capacity but smaller relative IRV ( P ≤ 0.03) than younger adults. Older compared with younger adults had greater total WOB at V̇ of 50 and 75 l/min (OA: 90 ± 43 vs. YA: 49 ± 21 J/min; P < 0.04 for both). At V̇e of 75 l/min, older adults had greater inspiratory elastic and resistive WOB (OA: 44 ± 27 vs. YA: 24 ± 22 and OA: 23 ± 15 vs. YA: 11 ± 3 J/min, respectively, P < 0.03 for both) and expiratory resistive WOB (OA: 23 ± 19 vs. YA: 14 ± 9 J/min, P = 0.02) than younger adults. These data demonstrate that aging-induced pulmonary alterations result in greater inspiratory elastic and resistive as well as expiratory resistive WOB, which may have implications for the integrated response during exercise. NEW& NOTEWORTHY Aging-induced changes to the pulmonary system result in increased work of breathing (WOB) during exercise. However, it is not known whether this higher WOB with aging is due to differences in elastic and/or resistive WOB. Herein, we demonstrate that older adults exhibited greater inspiratory elastic and resistive as well as expiratory resistive WOB during exercise.

Section: Methodsmentioning

confidence: 99%

Resistive and elastic work of breathing in older and younger adults during exercise

Journal of Applied Physiology

Cross

Iterson

et al. 2018

Self Cite

“…The IC and IC (% predicted) measured during exercise are reported. EFL was quantified as the percentage of the exercising V T that intersected or exceeded the MFVL (Chenoweth, Smith, Ferguson, Downey, & Harms, 2015;Johnson et al, 1999;Smith, Kurti, Meskimen, & Harms, 2017c;Smith, Rosenkranz, & Harms, 2014). One HFrEF patient did not perform valid IC manouevres and was not included in the ventilatory constraint analysis.…”

Section: Ventilatory Constraintsmentioning

confidence: 99%

Ventilatory constraints influence physiological dead space in heart failure

Experimental Physiology

Olson

2018

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Introduction: Heart failure patients with reduced ejection fraction (HFrEF) exhibit impaired ventilatory efficiency (i.e. greater ventilatory equivalent for carbon dioxide (VE/VCO2) slope), and elevated physiologic dead space (VD/VT). However, the impact of breathing strategy on VD/VT during submaximal exercise in HFrEF is unclear. Methods: HFrEF (n=9) and control (CTL, n=9)) participants performed constant load cycling exercise at similar ventilation (VE). Inspiratory capacity (IC), operating lung volumes and arterial blood gases were measured during submaximal exercise. Arterial blood gases were used to derive VD/VT, alveolar volume, dead space volume, alveolar ventilation, and dead space ventilation. Results: During submaximal exercise, HFrEF had greater VE/VCO2 slope and VD/VT than CTL (p=0.01). At similar VE, HFrEF had smaller tidal volumes and alveolar volumes (HFrEF: 1.11±0.33 vs. CTL: 1.66±0.37 L) (both p≤0.01), while dead space volume was not different (p=0.47). The augmented breathing frequency in HFrEF resulted in greater dead space ventilation compared to CTL (HFrEF: 15±4; CTL: 10±5 L/min) (p=0.048). HFrEF exhibited greater increases in expiratory reserve volume and lower IC (% predicted) than CTL (both p<0.05), which were significantly related to VD/VT and alveolar volume in HFrEF (all p<0.03). Conclusion: In HFrEF, the reduced tidal volume and alveolar volume elevate physiologic dead space during submaximal exercise, which is worsened in those with the greatest ventilatory constraints. These findings highlight the negative consequences of ventilatory constraints on physiologic dead space during submaximal exercise in HFrEF.

“…Maximum flow-volume loops were used to establish normal pulmonary function and give measures of forced vital capacity (FVC), forced expiratory volume in 1 s (FEV 1), and peak expiratory flow (PEF) (SensorMedics 229 Metabolic Cart, SensorMedics), and these values were expressed as percentages of predicted values (29). PIMAX was used to determine inspiratory muscle strength and was measured at residual volume as previously done (6,31,33).…”

Section: Subjectsmentioning

confidence: 99%

Cardiovascular consequences of the inspiratory muscle metaboreflex: effects of age and sex

American Journal of Physiology-Heart and Circulatory Physiology

Alexander

Hammer

et al. 2017

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With inspiratory muscle metaboreflex activation, we hypothesized that, compared with their younger counterparts, older men and women would exhibit greater ) increases in mean arterial pressure (MAP) and limb vascular resistance (LVR) and) decreases in limb blood flow (Q̇) but ) no sex differences would be present in older adults. Sixteen young adults [8 young men (YM) and 8 young women (YW), 18-24 yr] and 16 older adults [8 older men (OM) and 8 older women (OW), 60-73 yr] performed inspiratory resistive breathing tasks (IRBTs) at 2% and 65% of their maximal inspiratory pressure. During the IRBTs, breathing frequency was 20 breaths/min with a 50% duty cycle. At baseline and during the IRBTs, MAP was measured via automated oscillometry, Q̇ was determined via Doppler ultrasound, and LVR was calculated. The 65% IRBT led to significantly greater increases in MAP in OW (15.9 ± 8.1 mmHg) compared with YW (6.9 ± 1.4 mmHg) but not ( > 0.05) between OM (12.3 ± 5.7 mmHg) and YM (10.8 ± 5.7 mmHg). OW (-20.2 ± 7.2%) had greater ( < 0.05) decreases in Q̇ compared with YW (-9.4 ± 10.2%), but no significant differences were present between OM (-22.8 ± 9.7%) and YM (-22.7 ± 11.3%) during the 65% IRBT. The 65% IRBT led to greater ( < 0.05) increases in LVR in OW (48.2 ± 25.5%) compared with YW (19.7 ± 15.0%), but no differences ( > 0.05) existed among OM (54.4 ± 17.8%) and YM (47.1 ± 23.3%). No significant differences were present in MAP, Q̇, or LVR between OM and OW. These data suggest that OW exhibit a greater inspiratory muscle metaboreflex compared with YW, whereas no differences between OM and YM existed. Finally, sex differences in the inspiratory muscle metaboreflex are not present in older adults. Premenopausal women exhibit an attenuated inspiratory muscle metaboreflex compared with young men; however, it is unknown whether these sex differences are present in older adults. Older women exhibited a greater inspiratory muscle metaboreflex compared with premenopausal women, whereas no differences were present between older and younger men.