TY - JOUR
T1 - Combined influence of inspiratory loading and locomotor subsystolic cuff inflation on cardiovascular responses during submaximal exercise
AU - Smith, Joshua R.
AU - Bruhn, Eric J.
AU - Berg, Jessica D.
AU - Nur, Amran A.
AU - Villarraga, Nicolas
AU - Olson, Thomas P.
N1 - Publisher Copyright:
© 2020 the American Physiological Society
PY - 2020/5
Y1 - 2020/5
N2 - It is unknown if simultaneous stimulation of the respiratory and locomotor muscle afferents via inspiratory loading (IL) and locomotor subsystolic cuff inflation (CUFF) influences the cardiovascular responses during exercise. We hypothesized that combined IL and CUFF (IL + CUFF) will result in greater increases in blood pressure (MAP) and systemic vascular resistance (SVR) than IL and CUFF alone during exercise. Eight adults (6 males/2 females) were enrolled and performed four 10-min bouts of constant-load cycling eliciting 40% maximal oxygen uptake on a single day. For each exercise bout, the first 5 min consisted of spontaneous breathing. The second 5 min consisted of voluntary hyperventilation (i.e., breathing frequency of 40 breaths/ min) with IL (30% maximum inspiratory pressure), CUFF (80 mmHg), IL + CUFF, or no intervention (CTL) in randomized order. During exercise, cardiac output and MAP were determined via open-circuit acetylene wash-in and manual sphygmomanometry, respectively, and SVR was calculated. Across CTL, IL, CUFF, and IL + CUFF, MAP was greater with each condition (CTL: 97 ∓ 14; IL: 106 ∓ 13; CUFF: 114 ∓ 14; IL + CUFF: 119 ∓ 15 mmHg, all P ≺ 0.02). Furthermore, SVR was greater with IL + CUFF compared with IL, CUFF, and CTL (CTL: 6.6 ∓ 1.1; IL: 7.5 ∓ 1.4; CUFF: 7.5 ∓ 1.3; IL + CUFF: 8.2 ∓ 1.4 mmHg·L-1·min-1, all P ≺ 0.02). Cardiac output was not different across conditions (CTL: 15.2 ∓ 3.8; IL: 14.8 ∓ 3.7; CUFF: 15.6 ∓ 3.5; IL + CUFF: 14.7 ∓ 4.3 L/min, all P ≻ 0.05). These data demonstrate that simultaneous stimulation of respiratory and locomotor muscle afferent feedback results in additive MAP and SVR responses than IL and CUFF alone during submaximal exercise. These findings have important clinical implications for populations with exaggerated locomotor and respiratory muscle reflex feedbacks.
AB - It is unknown if simultaneous stimulation of the respiratory and locomotor muscle afferents via inspiratory loading (IL) and locomotor subsystolic cuff inflation (CUFF) influences the cardiovascular responses during exercise. We hypothesized that combined IL and CUFF (IL + CUFF) will result in greater increases in blood pressure (MAP) and systemic vascular resistance (SVR) than IL and CUFF alone during exercise. Eight adults (6 males/2 females) were enrolled and performed four 10-min bouts of constant-load cycling eliciting 40% maximal oxygen uptake on a single day. For each exercise bout, the first 5 min consisted of spontaneous breathing. The second 5 min consisted of voluntary hyperventilation (i.e., breathing frequency of 40 breaths/ min) with IL (30% maximum inspiratory pressure), CUFF (80 mmHg), IL + CUFF, or no intervention (CTL) in randomized order. During exercise, cardiac output and MAP were determined via open-circuit acetylene wash-in and manual sphygmomanometry, respectively, and SVR was calculated. Across CTL, IL, CUFF, and IL + CUFF, MAP was greater with each condition (CTL: 97 ∓ 14; IL: 106 ∓ 13; CUFF: 114 ∓ 14; IL + CUFF: 119 ∓ 15 mmHg, all P ≺ 0.02). Furthermore, SVR was greater with IL + CUFF compared with IL, CUFF, and CTL (CTL: 6.6 ∓ 1.1; IL: 7.5 ∓ 1.4; CUFF: 7.5 ∓ 1.3; IL + CUFF: 8.2 ∓ 1.4 mmHg·L-1·min-1, all P ≺ 0.02). Cardiac output was not different across conditions (CTL: 15.2 ∓ 3.8; IL: 14.8 ∓ 3.7; CUFF: 15.6 ∓ 3.5; IL + CUFF: 14.7 ∓ 4.3 L/min, all P ≻ 0.05). These data demonstrate that simultaneous stimulation of respiratory and locomotor muscle afferent feedback results in additive MAP and SVR responses than IL and CUFF alone during submaximal exercise. These findings have important clinical implications for populations with exaggerated locomotor and respiratory muscle reflex feedbacks.
KW - Blood pressure
KW - Cardiac output
KW - Exercise pressor reflex
KW - Respiratory muscle metaboreflex
KW - Venous distention
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U2 - 10.1152/japplphysiol.00781.2019
DO - 10.1152/japplphysiol.00781.2019
M3 - Article
C2 - 32240016
AN - SCOPUS:85084379312
SN - 8750-7587
VL - 128
SP - 1338
EP - 1345
JO - Journal of applied physiology
JF - Journal of applied physiology
IS - 5
ER -