126 EFFECTS OF TRAINING ON THE GROWTH HORMONE (GH) RESPONSE TO CONSTANT-LOAD EXERCISE

The purpose of this study was to determine the effects of bed-rest-induced deconditioning on changes in O2 uptake (VO2) kinetics, O2 deficit, steady-state VO2, and recovery VO2 during the performance of constant-load exercise. Five male subjects (36–40 yr) underwent 7 days of continuous bed rest (BR) in the head-down (-6 degrees) position. Two days before (pre) and the day after (post) BR each subject performed one submaximal exercise test in the supine and one in the upright position consisting of 5 min of rest, 5 min of cycle ergometer exercise at 700 kg.m/min, and 10 min of recovery from exercise. VO2 was measured continuously in all tests from 2-liter aliquot gas samples collected every 30 s. Following BR steady-state VO2 was unchanged in supine and upright exercise. In the supine position BR did not change total exercise VO2, O2 deficit, or total recovery VO2. However, compared with pre-BR, total exercise VO2 decreased (P less than 0.05) from 7.41 +/- 0.11 to 7.23 +/- 0.17 liters, O2 deficit increased (P less than 0.05) from 1.15 +/- 0.05 to 1.41 +/- 0.07 liters, and total recovery VO2 increased (P less than 0.05) from 5.17 +/- 0.11 to 5.47 +/- 0.17 liters during the post-BR upright test. Despite the ability to attain similar steady-state VO2 within 5 min, bed-rest-induced deconditioning resulted in a reduction of total VO2 capacity and an increase in the O2 deficit during submaximal constant-load exercise. This change in VO2 kinetics is found only with exercise in the upright rather than supine position implicating orthostatic mechanisms in the delayed response to submaximal exercise.

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Greater Exercise Pressor Response Is Associated With Impaired Claudication Outcomes in Symptomatic Peripheral Artery Disease

Angiology ◽

10.1177/0003319718790876 ◽

2018 ◽

Vol 70 (3) ◽

pp. 220-228 ◽

Cited By ~ 4

Author(s):

Andrew W. Gardner ◽

Polly S. Montgomery ◽

Ming Wang ◽

Chixiang Chen ◽

Marcos Kuroki ◽

...

Keyword(s):

Heart Rate ◽

Peripheral Artery Disease ◽

Pressor Response ◽

Constant Load ◽

Rate Pressure Product ◽

Treadmill Test ◽

Peripheral Artery ◽

Negatively Associated ◽

Artery Disease ◽

Constant Load Exercise

We determined whether a greater exercise pressor response during a constant-load treadmill test was associated with lower peak walking time (PWT) and claudication onset time (COT) measured during a graded maximal treadmill test in 304 patients with symptomatic peripheral artery disease (PAD). The exercise pressor response was assessed by measuring heart rate and blood pressure (BP) at rest and during a constant-load treadmill test (speed = 2 mph, grade = 0%). After only 2 minutes of walking, mean heart rate increased by 26 beats/min from rest and mean systolic BP increased by 16 mm Hg. In adjusted analyses, increases in systolic BP ( P = .021), heart rate ( P = .002), mean arterial pressure ( P = .034), and rate–pressure product ( P < .001) from rest to 2 minutes of constant-load exercise were negatively associated with COT. Similarly, increases in heart rate ( P = .012) and rate–pressure product ( P = .018) from rest to 2 minutes of constant-load exercise were negatively associated with PWT. A greater exercise pressor response observed after only 2 minutes of walking at no incline was independently associated with impaired claudication outcomes in patients with symptomatic PAD. The implication is that the exercise pressor response is an important and easily obtained clinical measurement that partially explains differences in PWT and COT.

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Effects of surgical face masks on cardiopulmonary parameters during steady state exercise

Scientific Reports ◽

10.1038/s41598-020-78643-1 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

J. Lässing ◽

R. Falz ◽

C. Pökel ◽

S. Fikenzer ◽

U. Laufs ◽

...

Keyword(s):

Heart Rate ◽

Steady State ◽

Airway Resistance ◽

Perceived Exertion ◽

Endurance Performance ◽

Constant Load ◽

Rating Of Perceived Exertion ◽

Lactate Minimum ◽

Load Tests ◽

Constant Load Exercise

AbstractWearing face masks reduce the maximum physical performance. Sports and occupational activities are often associated with submaximal constant intensities. This prospective crossover study examined the effects of medical face masks during constant-load exercise. Fourteen healthy men (age 25.7 ± 3.5 years; height 183.8 ± 8.4 cm; weight 83.6 ± 8.4 kg) performed a lactate minimum test and a body plethysmography with and without masks. They were randomly assigned to two constant load tests at maximal lactate steady state with and without masks. The cardiopulmonary and metabolic responses were monitored using impedance cardiography and ergo-spirometry. The airway resistance was two-fold higher with the surgical mask (SM) than without the mask (SM 0.58 ± 0.16 kPa l−1 vs. control [Co] 0.32 ± 0.08 kPa l−1; p < 0.01). The constant load tests with masks compared with those without masks resulted in a significantly different ventilation (77.1 ± 9.3 l min−1 vs. 82.4 ± 10.7 l min−1; p < 0.01), oxygen uptake (33.1 ± 5 ml min−1 kg−1 vs. 34.5 ± 6 ml min−1 kg−1; p = 0.04), and heart rate (160.1 ± 11.2 bpm vs. 154.5 ± 11.4 bpm; p < 0.01). The mean cardiac output tended to be higher with a mask (28.6 ± 3.9 l min−1 vs. 25.9 ± 4.0 l min−1; p = 0.06). Similar blood pressure (177.2 ± 17.6 mmHg vs. 172.3 ± 15.8 mmHg; p = 0.33), delta lactate (4.7 ± 1.5 mmol l−1 vs. 4.3 ± 1.5 mmol l−1; p = 0.15), and rating of perceived exertion (6.9 ± 1.1 vs. 6.6 ± 1.1; p = 0.16) were observed with and without masks. Surgical face masks increase airway resistance and heart rate during steady state exercise in healthy volunteers. The perceived exertion and endurance performance were unchanged. These results may improve the assessment of wearing face masks during work and physical training.

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Characterizing The Ventilatory Response To Constant Load Exercise Above And Below Critical Power

Medicine & Science in Sports & Exercise ◽

10.1249/01.mss.0000538209.16132.5e ◽

2018 ◽

Vol 50 (5S) ◽

pp. 670

Author(s):

Keren Constantini ◽

Cameron A. Nowrouzi ◽

Courtney E. Wheelock ◽

Robert F. Chapman

Keyword(s):

Critical Power ◽

Ventilatory Response ◽

Constant Load ◽

Constant Load Exercise

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