Статті в журналах: "Constant load exercise"

1

Hussain, S. N., R. L. Pardy, and J. A. Dempsey. "Mechanical impedance as determinant of inspiratory neural drive during exercise in humans." Journal of Applied Physiology 59, no. 2 (August 1, 1985): 365–75. http://dx.doi.org/10.1152/jappl.1985.59.2.365.

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Five healthy males exercised progressively with small 2-min increments in work load. We measured inspiratory drive (occlusion pressure, P0.1), pulmonary resistance (RL), dynamic pulmonary compliance (Cdyn), transdiaphragmatic pressure (Pdi), and diaphragmatic electromyogram (EMGdi). Minute ventilation (VE), mean inspiratory flow rate (VT/TI), and P0.1 all increased exponentially with increased work load, but P0.1 increased at a faster rate than did VT/TI or VE. Thus effective impedance (P0.1/VT/TI) rose throughout exercise. The increasing P0.1 was mostly due to augmented Pdi and coincided with increased EMGdi during this initial portion of inspiration. We found no consistent change in RL or Cdyn throughout exercise. With He breathing (80% He-20% O2), RL was reduced at all work loads; P0.1 fell in comparison with air-breathing values and VE, VT, and VT/TI rose in moderate and heavy work; and P0.1/VT/TI was unchanged with increasing exercise loads. Step reductions in gas density at a constant work load of any intensity showed an immediate reduction in the rate of rise of EMGdi and Pdi followed by increased VT/TI, breathing frequency, and hypocapnia. These changes were maintained during prolonged periods of unloading and were immediately reversible on return to air breathing. These data are consistent with the existence of a reflex effect on the magnitude of inspiratory neural drive during exercise that is sensitive to the load presented by the normal mechanical time constant of the respiratory system. This “load” is a significant determinant of the hyperpneic response and thus of the maintenance of normocapnia during exercise.

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2

Marino, F. E. "The limitations of the constant load and self-paced exercise models of exercise physiology." Comparative Exercise Physiology 8, no. 1 (January 1, 2012): 3–9. http://dx.doi.org/10.3920/cep11012.

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The fundamental tenets of exercise physiology are to describe energy transformations during physical work and make predictions about physical performance during different conditions. Historically, the most popular method to observe such responses during exercise has been the constant load or fixed intensity protocol based largely on the assumption that there is a threshold response of the organism under given conditions. However, constant load exercise does not fully allow for randomness or variability as the biological system is overridden by a predetermined externally imposed load which cannot be altered. Conversely, in self-regulated (paced) exercise there is almost an immediate reduction in power output and muscle recruitment upon commencing exercise. This observation suggests the existence of a neural inhibitory command processes. This difference in regulation demonstrates the inherent importance of variability in the biological system; for in tightly controlled energy expenditure, as is the case during constant load exercise, sensory cues cannot be fully integrated to provide a more appropriate response to the given task. The collective evidence from conventional constant load versus self-regulated exercise studies suggest that energy transformations are indeed different so that the inherent biological variability accounts for the different results achieved by the two experimental paradigms.

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3

Gairola, Anjuli, Thariana Salazar, Ruth Georges, and Kristen Betterman. "Session RPE During A Constant Load Submaximal Treadmill Exercise." Medicine & Science in Sports & Exercise 52, no. 7S (July 2020): 631. http://dx.doi.org/10.1249/01.mss.0000681164.21004.45.

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4

Yamazaki, F., N. Fujii, R. Sone, and H. Ikegami. "Responses of sweating and body temperature to sinusoidal exercise in physically trained men." Journal of Applied Physiology 80, no. 2 (February 1, 1996): 491–95. http://dx.doi.org/10.1152/jappl.1996.80.2.491.

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The effect of physical training on the dynamic responses of sweating to transient exercise is still controversial. We determined the phase response and amplitude response (delta) of sweating rate and body temperature to sinusoidal exercise in physically trained and untrained subjects. Eight trained and seven untrained male subjects exercised on a cycle ergometer with a constant load for 30 min; for the next 28 min, they exercised with a sinusoidal load. The sinusoidal load variation ranged from approximately 10 to 60% of peak O2 uptake with a 4-min period. The ambient temperature and the relative humidity during exercise were 25 degrees C and 35%, respectively. There was no difference between the groups in the phase lags of esophageal temperature (Tes) and mean skin temperature (Tsk), whereas the phase lags of sweating rates for the chest and forearm were significantly shorter in the trained group (P < 0.05). The delta of Tes and Tsk per 1 W of exercise load in the trained group was significantly smaller than that in the untrained group (both, P < 0.05), whereas there was no difference between the groups in the delta of sweating rate for the chest and forearm. We conclude that subjects who have undergone long-term physical training show prompter dynamic characteristics of sweating response compared with untrained subjects and have a higher capacity to maintain constant body temperature during exercise at transient load.

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5

WELTMAN, ARTHUR, JUDY Y. WELTMAN, CHRISTOPHER J. WOMACK, SHALA E. DAVIS, JEFFREY L. BLUMER, GLENN A. GAESSER, and MARK L. HARTMAN. "Exercise training decreases the growth hormone (GH) response to acute constant-load exercise." Medicine &amp Science in Sports &amp Exercise 29, no. 5 (May 1997): 669–76. http://dx.doi.org/10.1097/00005768-199705000-00013.

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6

Pepin, Véronique, Didier Saey, Claude H. Côté, Pierre LeBlanc, and François Maltais. "Susceptibility to Muscle Fatigue and Lung Mechanics in Chronic Obstructive Pulmonary Disease." Clinical & Investigative Medicine 30, no. 3 (June 1, 2007): 27. http://dx.doi.org/10.25011/cim.v30i3.1721.

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Background: Contractile fatigue of the quadriceps occurs in a significant proportion of patients with COPD after constant-load cycling exercise. Dynamic hyperinflation, by altering cardiac output during exercise, could contribute to fatigue susceptibility in this population. The purpose of this study was to compare operational lung volumes during constant workrate exercise between COPD patients who do and those who do not develop contractile fatigue of the quadriceps (fatiguers vs non-fatiguers). Methods: Sixty-two patients with COPD (FEV1: 46±16%) completed a constant-load cycling test at 80% of the peak workrate achieved during progressive cycle ergometry. Ventilatory parameters were monitored breath-by-breath, while inspiratory capacity maneuvers were obtained every other minute during constant-load cycling. Quadriceps twitch force was measured with magnetic stimulation of the femoral nerve before and after the test. Muscle fatigue was defined as a post-exercise reduction in quadriceps twitch force of more than 15% of the resting value. Results: Forty patients (65%) developed muscle fatigue after constant-load cycling. No significant differences were found between fatiguers and non-fatiguers with respect to age, body mass index, resting lung function, peak oxygen consumption, and endurance time to constant-load exercise. Change in inspiratory capacity from rest to end-exercise (DIC) was similar between both subgroups (DIC: 0.56±0.32L vs 0.56±0.47L for fatiguers and non-fatiguers respectively, P=0.99). Conclusion: Susceptibility to muscle fatigue could not be predicted by exercise duration or by the degree of dynamic hyperinflation in patients with COPD.

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7

Friden, J., P. N. Sfakianos, and A. R. Hargens. "Muscle soreness and intramuscular fluid pressure: comparison between eccentric and concentric load." Journal of Applied Physiology 61, no. 6 (December 1, 1986): 2175–79. http://dx.doi.org/10.1152/jappl.1986.61.6.2175.

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This study investigates the dynamic and resting intramuscular pressures associated with eccentric and concentric exercise of muscles in a low-compliance compartment. The left and righ leg anterior compartments of eight healthy males (ages 22–32 yr) were exercised by either concentric or eccentric contractions of the same load (400 submaximal contractions at constant rate, 20/min for 20 min at a load corresponding to 15% of individual maximal dorsiflexion torque). Tissue fluid pressures were measured with the slit-catheter technique before, during, and after the exercise. Average peak intramuscular pressure generated during eccentric exercise (236 mmHg) was significantly greater than during concentric exercise (157 mmHg, P less than 0.001). Peak isometric contraction pressure in the eccentrically exercised compartment was significantly higher both within 20 min postexercise and on the second postexercise day (P less than 0.001). Resting pressure 2 days postexercise was significantly higher on the eccentrically exercised side (10.5 mmHg) compared with the concentrically exercised (4.4 mmHg, P less than 0.05). The ability to sustain tension during postexercise isometric contractions was impaired on the “eccentric” side. Soreness was exclusively experienced in the eccentrically exercised muscles. We conclude that eccentric exercise causes significant intramuscular pressure elevation in the anterior compartment, not seen following concentric exercise, and that this may be one of the factors associated with development of delayed muscle soreness in a tight compartment.

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8

Takahashi, Shinji, Tomonori Chiba, Hiroaki Ishii, and Takahiko Nishijima. "Validity of Expired Gas Simulation Model during Constant Load Exercise." International Journal of Sport and Health Science 1, no. 1 (2003): 119–28. http://dx.doi.org/10.5432/ijshs.1.119.

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9

Yano, Tokuo, Yasuhito Kumazaki, and Katsumi Asano. "Kinetics of Mixed Venous CO2 Pressure in Constant-Load Exercise." Applied Human Science 14, no. 3 (1995): 155–56. http://dx.doi.org/10.2114/ahs.14.155.

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10

Milanese, Manlio, Riccardo Saporiti, Stefano Bartolini, Riccardo Pellegrino, Michele Baroffio, Vito Brusasco, and Emanuele Crimi. "Bronchodilator effects of exercise hyperpnea and albuterol in mild-to-moderate asthma." Journal of Applied Physiology 107, no. 2 (August 2009): 494–99. http://dx.doi.org/10.1152/japplphysiol.00302.2009.

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In asthmatic patients, either bronchodilatation or bronchoconstriction may develop during exercise. In 18 patients with mild-to-moderate asthma, we conducted two studies with the aims to 1) quantify the bronchodilator effect of hyperpnea induced by incremental-load maximum exercise compared with effects of inhaled albuterol ( study 1, n = 10) and 2) determine the time course of changes in airway caliber during prolonged constant-load exercise ( study 2, n = 8). In both studies, it was also investigated whether the bronchodilator effects of exercise hyperpnea and albuterol are additive. Changes in airway caliber were measured by changes in partial forced expiratory flow. In study 1, incremental-load exercise was associated with a bronchodilatation that was ∼60% of the maximal bronchodilatation obtainable with 1,500 μg of albuterol. In study 2, constant-load exercise was associated with an initial moderate bronchodilatation and a late airway renarrowing. In both studies, premedication with inhaled albuterol (400 μg) promoted sustained bronchodilatation during exercise, which was additive to that caused by exercise hyperpnea. In conclusion, in mild-to-moderate asthmatic individuals, hyperpnea at peak exercise was associated with a potent yet not complete bronchodilatation. During constant-load exercise, a transient bronchodilatation was followed by airway renarrowing, suggesting prevalence of constrictor over dilator effects of hyperpnea. Finally, the bronchodilator effect of hyperpnea was additive to that of albuterol.

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11

Raymer, Graydon H., Sean C. Forbes, John M. Kowalchuk, R. Terry Thompson, and Greg D. Marsh. "Prior exercise delays the onset of acidosis during incremental exercise." Journal of Applied Physiology 102, no. 5 (May 2007): 1799–805. http://dx.doi.org/10.1152/japplphysiol.01151.2006.

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The effects of prior moderate- and prior heavy-intensity exercise on the subsequent metabolic response to incremental exercise were examined. Healthy, young adult subjects ( n = 8) performed three randomized plantar-flexion exercise tests: 1) an incremental exercise test (∼0.6 W/min) to volitional fatigue (Ramp); 2) Ramp preceded by 6 min of moderate-intensity, constant-load exercise below the intracellular pH threshold (pHT; Mod-Ramp); and 3) Ramp preceded by 6 min of heavy-intensity, constant-load exercise above pHT (Hvy-Ramp); the constant-load and incremental exercise periods were separated by 6 min of rest. 31P-magnetic resonance spectroscopy was used to continuously monitor intracellular pH, phosphocreatine concentration ([PCr]), and inorganic phosphate concentration ([Pi]). No differences in exercise performance or the metabolic response to exercise were observed between Ramp and Mod-Ramp. However, compared with Ramp, a 14% (SD 10) increase ( P < 0.01) in peak power output (PPO) was observed in Hvy-Ramp. The improved exercise performance in Hvy-Ramp was accompanied by a delayed ( P = 0.01) onset of intracellular acidosis [Hvy-Ramp 60.4% PPO (SD 11.7) vs. Ramp 45.8% PPO (SD 9.4)] and a delayed ( P < 0.01) onset of rapid increases in [Pi]/[PCr] [Hvy-Ramp 61.5% PPO (SD 12.0) vs. Ramp 45.1% PPO (SD 9.1)]. In conclusion, prior heavy-intensity exercise delayed the onset of intracellular acidosis and enhanced exercise performance during a subsequent incremental exercise test.

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12

Gardner, Andrew W., Polly S. Montgomery, Ming Wang, Chixiang Chen, Marcos Kuroki, and Danielle Jin-Kwang Kim. "Greater Exercise Pressor Response Is Associated With Impaired Claudication Outcomes in Symptomatic Peripheral Artery Disease." Angiology 70, no. 3 (August 6, 2018): 220–28. http://dx.doi.org/10.1177/0003319718790876.

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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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13

Marino, Frank E. "The limitations of the constant load and self-paced exercise models of exercise physiology." Comparative Exercise Physiology 7, no. 04 (November 2010): 173–78. http://dx.doi.org/10.1017/s1755254012000013.

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14

Harms, C. A., L. B. Daniels, W. I. Marshall, and C. S. Ferguson. "EFFECT OF EXERCISE MODE ON LUNG DIFFUSION CAPACITY DURING INCREMENTAL AND CONSTANT LOAD EXERCISE." Medicine & Science in Sports & Exercise 31, Supplement (May 1999): S330. http://dx.doi.org/10.1097/00005768-199905001-01660.

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15

Reis, Victor M., Eduardo B. Neves, Nuno Garrido, Ana Sousa, André L. Carneiro, Carlo Baldari, and Tiago Barbosa. "Oxygen Uptake On-Kinetics during Low-Intensity Resistance Exercise: Effect of Exercise Mode and Load." International Journal of Environmental Research and Public Health 16, no. 14 (July 15, 2019): 2524. http://dx.doi.org/10.3390/ijerph16142524.

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Oxygen uptake (VO2) kinetics has been analyzed through mathematical modeling of constant work-rate exercise, however, the exponential nature of the VO2 response in resistance exercise is currently unknown. The present work assessed the VO2 on-kinetics during two different sub maximal intensities in the inclined bench press and in the seated leg extension exercise. Twelve males (age: 27.2 ± 4.3 years, height: 177 ± 5 cm, body mass: 79.0 ± 10.6 kg and estimated body fat: 11.4 ± 4.1%) involved in recreational resistance exercise randomly performed 4-min transitions from rest to 12% and 24% of 1 repetition maximum each, of inclined bench press (45°) and leg extension exercises. During all testing, expired gases were collected breath-by-breath with a portable gas analyzer (K4b2, Cosmed, Italy) and VO2 on-kinetics were identified using a multi-exponential mathematical model. Leg extension exercise exhibited a higher R-square, compared with inclined bench press, but no differences were found in-between exercises for the VO2 kinetics parameters. VO2 on-kinetics seems to be more sensitive to muscle related parameters (upper vs. lower body exercise) and less to small load variations in the resistance exercise. The absence of a true slow component indicates that is possible to calculate low-intensity resistance exercise energy cost based solely on VO2 measurements.

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16

Binzoni, T., G. Ferretti, K. Schenker, and P. Cerretelli. "Phosphocreatine hydrolysis by 31P-NMR at the onset of constant-load exercise in humans." Journal of Applied Physiology 73, no. 4 (October 1, 1992): 1644–49. http://dx.doi.org/10.1152/jappl.1992.73.4.1644.

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The kinetics of phosphocreatine (PC) breakdown in human plantar flexors at the onset of constant-load aerobic exercise was determined by high-resolution 31P-nuclear magnetic resonance spectroscopy (NMRS). The half time of the process (t1/2PC) was obtained by fitting curves (n = 13) from five subjects at various aerobic work loads for which muscle pH was not different from that at rest. Steady-state PC concentration ([PC]) was not < 70% of the resting value and was linearly related to the work load (w) ([PC] = -3.01 +/- 0.08 w + 1 (r = 0.48, 2P < 0.1)). The average t1/2PC was 16.2 s and was independent of work load. Because the half time of the muscle PC kinetics reflects the half time of the O2 uptake (MO2) kinetics (t1/2MO2), the latter is equal to that found earlier in the isolated perfused dog gastrocnemius. Whereas in the dog the above t1/2MO2 compares well with the homologous half time of the O2 uptake at the alveolar level, in humans such equivalence is found only at extremely low work loads, when the transient contribution by anaerobic glycolysis is negligible.

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17

Bergstrom, Haley C., Taylor K. Dinyer, Pasquale J. Succi, Caleb C. Voskuil, and Terry J. Housh. "Applications of the Critical Power Model to Dynamic Constant External Resistance Exercise: A Brief Review of the Critical Load Test." Sports 9, no. 2 (January 21, 2021): 15. http://dx.doi.org/10.3390/sports9020015.

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The study and application of the critical power (CP) concept has spanned many decades. The CP test provides estimates of two distinct parameters, CP and W′, that describe aerobic and anaerobic metabolic capacities, respectively. Various mathematical models have been used to estimate the CP and W′ parameters across exercise modalities. Recently, the CP model has been applied to dynamic constant external resistance (DCER) exercises. The same hyperbolic relationship that has been established across various continuous, whole-body, dynamic movements has also been demonstrated for upper-, lower-, and whole-body DCER exercises. The asymptote of the load versus repetition relationship is defined as the critical load (CL) and the curvature constant is L′. The CL and L′ can be estimated from the same linear and non-linear mathematical models used to derive the CP. The aims of this review are to (1) provide an overview of the CP concept across continuous, dynamic exercise modalities; (2) describe the recent applications of the model to DCER exercise; (3) demonstrate how the mathematical modeling of DCER exercise can be applied to further our understanding of fatigue and individual performance capabilities; and (4) make initial recommendations regarding the methodology for estimating the parameters of the CL test.

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18

Chaudhry, H., A. Holland, and J. Dormandy. "Comparison of Graded versus Constant Treadmill Test Protocols for Quantifying Intermittent Claudication." Vascular Medicine 2, no. 2 (May 1997): 93–97. http://dx.doi.org/10.1177/1358863x9700200204.

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The standard method for quantifying the symptoms of intermittent claudication is by using treadmill walking distance. It has recently been suggested that a graded exercise test is much more reproducible than a constant load exercise test. Graded protocols have also been claimed to abolish the placebo effect that has been reported with the constant load test. The reproducibility of absolute claudication distance (ACD) and initial claudication distance (ICD) using a constant load was compared to the graded load treadmill protocol. Fourteen patients (mean age 66 years) with varying severity of stable intermittent claudication were tested using a constant load (3.2 km/h, 10% gradient) and a graded load (3.2 km/h, 0% gradient increasing by 3.5% every 3 min). Patients were tested twice using each protocol in a random sequence, with a minimum 2 day interval between visits. Intra-class correlation coefficient (R) with a constant load protocol for ICD and ACD was R = 0.68, R = 0.93, respectively. With a graded protocol R = 0.84 for ICD and R = 0.98 for ACD. Relative coefficient of repeatability for ICD and ACD during constant load tests were 1.47 and 1.90 respectively and with a graded load test were 1.69 and 1.52 respectively. It was concluded that the graded load test was more reproducible than the constant load test but only by a small margin, whilst ACD was much more reproducible than ICD using either protocol.

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19

Keslacy, S., S. Matecki, J. Carra, F. Borrani, R. Candau, C. Prefaut, and M. Ramonatxo. "Effect of inspiratory threshold loading on ventilatory kinetics during constant-load exercise." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 289, no. 6 (December 2005): R1618—R1624. http://dx.doi.org/10.1152/ajpregu.00639.2004.

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Humoral factors play an important role in the control of exercise hyperpnea. The role of neuromechanical ventilatory factors, however, is still being investigated. We tested the hypothesis that the afferents of the thoracopulmonary system, and consequently of the neuromechanical ventilatory loop, have an influence on the kinetics of oxygen consumption (V̇o2), carbon dioxide output (V̇co2), and ventilation (V̇e) during moderate intensity exercise. We did this by comparing the ventilatory time constants (τ) of exercise with and without an inspiratory load. Fourteen healthy, trained men (age 22.6 ± 3.2 yr) performed a continuous incremental cycle exercise test to determine maximal oxygen uptake (V̇o2 max = 55.2 ± 5.8 ml·min−1·kg−1). On another day, after unloaded warm-up they performed randomized constant-load tests at 40% of their V̇o2 max for 8 min, one with and the other without an inspiratory threshold load of 15 cmH2O. Ventilatory variables were obtained breath by breath. Phase 2 ventilatory kinetics (V̇o2, V̇co2, and V̇e) could be described in all cases by a monoexponential function. The bootstrap method revealed small coefficients of variation for the model parameters, indicating an accurate determination for all parameters. Paired Student's t-tests showed that the addition of the inspiratory resistance significantly increased the τ during phase 2 of V̇o2 (43.1 ± 8.6 vs. 60.9 ± 14.1 s; P < 0.001), V̇co2 (60.3 ± 17.6 vs. 84.5 ± 18.1 s; P < 0.001) and V̇e (59.4 ± 16.1 vs. 85.9 ± 17.1 s; P < 0.001). The average rise in τ was 41.3% for V̇o2, 40.1% for V̇co2, and 44.6% for V̇e. The τ changes indicated that neuromechanical ventilatory factors play a role in the ventilatory response to moderate exercise.

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20

WAKUDA, Miku, and Yuusuke NISHIDA. "Characteristics of Heart Rate in Low Intensity Constant Load Arm Exercise:." Rigakuryoho Kagaku 26, no. 1 (2011): 7–11. http://dx.doi.org/10.1589/rika.26.7.

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21

Kapus, Jernej, Anton Ušaj, and Venceslav Kapus. "Some Metabolic Responses to Reduced Breathing Frequency During Constant Load Exercise." Medicina Sportiva 14, no. 1 (March 1, 2010): 13–18. http://dx.doi.org/10.2478/v10036-010-0003-8.

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CARETTI, DAVID M., and JEFFREY A. WHITLEY. "Exercise performance during inspiratory resistance breathing under exhaustive constant load work." Ergonomics 41, no. 4 (April 1998): 501–11. http://dx.doi.org/10.1080/001401398186973.

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23

Haverkamp, H. C., T. J. Wetter, D. F. Pegelow, and J. A. Dempsey. "VENTILATORY RESPONSES TO HIGH INTENSITY CONSTANT LOAD EXERCISE IN WOMEN RUNNERS." Medicine & Science in Sports & Exercise 33, no. 5 (May 2001): S59. http://dx.doi.org/10.1097/00005768-200105001-00329.

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24

McKeough, Zoe J., Jennifer A. Alison, Bradley A. Speers, and Peter T. P. Bye. "Physiological responses to high intensity, constant-load arm exercise in COPD." Respiratory Medicine 102, no. 3 (March 2008): 348–53. http://dx.doi.org/10.1016/j.rmed.2007.10.020.

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25

Palmer, G. S., L. B. Borghouts, T. D. Noakes, and J. A. Hawley. "METABOLIC RESPONSES TO CONSTANT LOAD VERSUS STOCHASTIC EXERCISE IN TRAINED CYCLISTS." Medicine & Science in Sports & Exercise 31, Supplement (May 1999): S54. http://dx.doi.org/10.1097/00005768-199905001-00084.

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26

Oyono-Enguelle, S., A. Heitz, J. Marbach, C. Ott, M. Gartner, A. Pape, J. C. Vollmer, and H. Freund. "Blood lactate during constant-load exercise at aerobic and anaerobic thresholds." European Journal of Applied Physiology and Occupational Physiology 60, no. 5 (1990): 321–30. http://dx.doi.org/10.1007/bf00713494.

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27

Kaltsakas, G., N. Chynkiamis, N. Anastasopoulos, P. Zeliou, V. Karapatoucha, K. Kotsifas, F. Diamantea, I. Inglezos, N. G. Koulouris, and I. Vogiatzis. "Interval versus constant-load exercise training in adults with Cystic Fibrosis." Respiratory Physiology & Neurobiology 288 (June 2021): 103643. http://dx.doi.org/10.1016/j.resp.2021.103643.

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28

Nikolopoulos, Vasilis, Melissa J. Arkinstall, and John A. Hawley. "Reduced Neuromuscular Activity with Carbohydrate Ingestion during Constant Load Cycling." International Journal of Sport Nutrition and Exercise Metabolism 14, no. 2 (April 2004): 161–70. http://dx.doi.org/10.1123/ijsnem.14.2.161.

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The purpose of this study was to determine the effect of carbohydrate ingestion before and during intense constant load cycling to volitional fatigue on surface electromyographic (sEMG) activity from the vastus lateralis (VL) and vastus medialis (VM) muscles. After 24-h diet and training control, 8 well-trained subjects [maximal O2 uptake (VO2max) 66 ± 2 ml · kg–1· min–1; mean ± SD] ingested 8 ml · kg–1 of either a 6.4% carbohydrate-electrolyte (CHO) or a placebo (PLA) solution immediately before, followed by 2 ml · kg–1 of the same solution every 15 min while cycling to exhaustion at 84 ± 1% of VO2max. Exercise time to fatigue was 13% longer with CHO ingestion compared to PLA (58:54 ± 8:48 vs. 51:18 ± 5:54 min:s, NS). VO2 (4.22 ± 0.11 vs. 4.20 ± 0.14 L · min–1), heart rate (172 ± 4 vs. 176 ± 4 beats · min–1), ratings of perceived effort (18 ± 0.1 vs. 19 ± 0.1), and rates of carbohydrate oxidation (314 ± 28 vs. 324 ± 26 μmol · kg–1 · min–1) were similar for both PLA and CHO at exhaustion. There was no main treatment effect of CHO ingestion on blood glucose or lactate concentrations, nor plasma prolactin levels either during exercise or at fatigue. However, CHO ingestion attenuated the rise in EMG root mean square (RMS) activity during the latter stages (>45 min) of exercise and at the point of exhaustion for both VM (0.325 ± 0.010 vs. 0.403 ± 0.020 mV; p = .006) and VL (0.298 ± 0.011 vs. 0.370 ± 0.007 mV; p = .0004). We conclude that in well-trained subjects, the ingestion of carbohydrate attenuated the increase in surface electromyographic activity during intense, constant load cycling leading to exhaustion in ~1 h. The precise mechanism(s) underlying this effect cannot be attributed to alterations in CHO availability but, instead, may be linked to changes in afferent sensory input.

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Hamada, Naomi, Tsuyoshi Wadazumi, Yoko Hirata, Mayumi Kuriyama, Kanji Watanabe, Hitoshi Watanabe, Nobuko Hongu, and Norie Arai. "Single Ingestion of Trehalose Enhances Prolonged Exercise Performance by Effective Use of Glucose and Lipid in Healthy Men." Nutrients 13, no. 5 (April 24, 2021): 1439. http://dx.doi.org/10.3390/nu13051439.

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Trehalose increases blood glucose levels slowly and induces a slight insulin response. The present study aimed to study the effect of trehalose on prolonged exercise performance. The participants were 12 healthy men (age: 21.3 ± 0.9 y). After an overnight fast (12 h), they first exercised with a constant load (intensity: 40% V˙O2peak) for 60 min using a bicycle ergometer. They continued to exercise with a constant load (40% V˙O2peak) for 30 min between four sets of the 30-s Wingate test. After the 1st set, each participant ingested 500 mL water (control), 8% glucose, or 8% trehalose in three trials. These three trials were at least one week apart and were conducted in a double-blind and randomized crossover manner. Blood was collected for seven biochemical parameters at 12 time points during the experiment. The area under the curve of adrenaline after ingestion of trehalose was significantly lower than that for water and tended to be lower than that for glucose in the later stage of the exercise. Lower secretion of adrenaline after a single dose of 8% trehalose during prolonged exercise reflected the preservation of carbohydrates in the body in the later stage of the exercise. In conclusion, a single ingestion of trehalose helped to maintain prolonged exercise performance.

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Spendier, Florian, Alexander Müller, Markus Korinek, and Peter Hofmann. "Intensity Thresholds and Maximal Lactate Steady State in Small Muscle Group Exercise." Sports 8, no. 6 (May 28, 2020): 77. http://dx.doi.org/10.3390/sports8060077.

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The aim of our study is to determine the first (LTP1) and the second (LTP2) lactate turn points during an incremental bicep curl test and to verify these turn points by ventilatory turn points (VT1 and VT2) and constant-load exercise tests. Twelve subjects performed a one-arm incremental bicep curl exercise (IET) after a one repetition maximum (1RM) test to calculate the step rate for the incremental exercise (1RM/45). Workload was increased every min at a rate of 30 reps/min until maximum. To verify LTPs, VT1 and VT2 were determined from spirometric data, and 30 min constant-load tests (CL) were performed at 5% Pmax below and above turn points. Peak load in IET was 5.3 ± 0.9 kg (Lamax: 2.20 ± 0.40 mmol·L−1; HRmax: 135 ± 15 b·min−1; VO2max: 1.15 ± 0.30 L·min−1). LTP1 was detected at 1.9 ± 0.6 kg (La: 0.86 ± 0.36 mmol·L−1; HR 90 ± 13 b·min−1; VO2: 0.50 ± 0.05 L·min−1) and LTP2 at 3.8 ± 0.7 kg (La: 1.38 ± 0.37 mmol·L−1; 106 ± 10 b·min−1; VO2: 0.62 ± 0.11 L·min−1). Constant-load tests showed a lactate steady-state in all tests except above LTP2, with early termination after 16.5 ± 9.1 min. LTP1 and LTP2 could be determined in IET, which were not significantly different from VT1/VT2. Constant-load exercise validated the three-phase concept, and a steady-state was found at resting values below VT1 and in all other tests except above LTP2. It is suggested that the three-phase model is also applicable to small muscle group exercise.

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Meyer, Tim, Nina Gäßler, and Wilfried Kindermann. "Determination of “Fatmax” with 1 h cycling protocols of constant load." Applied Physiology, Nutrition, and Metabolism 32, no. 2 (April 2007): 249–56. http://dx.doi.org/10.1139/h06-108.

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Several earlier studies were aimed at determining an exercise intensity that elicits maximal fat oxidation (Fatmax). However, these studies employed few different intensities or used exercise periods of too short a duration. All investigators described intensity with reference to maximal ergometric values, which might lead to metabolically inhomogeneous workloads between individuals. The aim of this study was to determine Fatmax by overcoming these methodological shortcomings of earlier investigations. Ten healthy recreational athletes (29 ± 5 y; 75 ± 6 kg; 1.81 ± 0.04 m) conducted an initial incremental cycling test to determine VO2 peak (59.2 ± 6.1 mL·min–1·kg–1) and individual anaerobic threshold (IAT; 221 ± 476 W). Within 4 weeks, 5 constant-load tests of 1 h duration were carried out at 55%, 65%, 75%, 85%, and 95% IAT. During all tests indirect calorimetry (MetaMax I, Cortex, Leipzig, Germany) served to quantify fat oxidation. Capillary blood sampling for lactate measurements was conducted every 15 min. All subjects remained in a lactate steady state during the constant load tests, which minimized influences from excess CO2. There was no difference between the 5 intensities for the percentage of energy from fat metabolism (p = 0.12). Additionally, the intensities led to similar absolute amounts of oxidized fat (p = 0.34). However, there was a significant increase in fat metabolism with increasing exercise duration (p = 0.04). It is impossible to define one theoretical optimal intensity for fat oxidation that is true in all individuals. It is thus mandatory to perform an individual assessment with indirect calorimetry. Intra-individual day-to-day variation might render the use of several tests of long duration less applicable than incremental testing with stages of sufficient duration.

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Oyake, Kazuaki, Yasuto Baba, Yuki Suda, Jun Murayama, Ayumi Mochida, Yuki Ito, Honoka Abe, Kunitsugu Kondo, Yohei Otaka, and Kimito Momose. "A Single Bout of Constant-Load Exercise Test for Estimating the Time Constant of Oxygen Uptake Kinetics in Individuals With Stroke." Annals of Rehabilitation Medicine 45, no. 4 (August 31, 2021): 304–13. http://dx.doi.org/10.5535/arm.21087.

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Objective To examine the relationship between the time constant of oxygen uptake kinetics during the onset of exercise (τVO2) estimated from a single exercise bout and that obtained from three averaged exercise bouts in individuals with stroke.Methods Twenty participants with stroke performed three bouts of a constant-load pedaling exercise at approximately 80% of the workload corresponding to the ventilatory threshold to estimate τVO2. The VO2 data from the first trial of three bouts were used to estimate τVO2 for a single bout. Additionally, data collected from three bouts were ensemble-averaged to obtain τVO2 for three averaged bouts as the criterion.Results There was a very high correlation between τVO2 for a single bout (34.8±14.0 seconds) and τVO2 for three averaged bouts (38.5±13.4 seconds) (r=0.926, p<0.001). However, τVO2 for a single bout was smaller than that for three averaged bouts (p=0.006).Conclusion τVO2 for a single bout could reflect the relative difference in τVO2 for three averaged bouts among individuals with stroke. However, it should be noted that τVO2 for a single bout may be underestimated compared to τVO2 for three averaged bouts.

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Horiuchi, Masahiro, and John M. Kowalchuk. "Heterogeneity of Muscle Deoxygenation Kinetics during Constant-load Moderate- and Heavy-exercise." Medicine & Science in Sports & Exercise 40, Supplement (May 2008): S117. http://dx.doi.org/10.1249/01.mss.0000321957.67990.d0.

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MAIONE, D. "Constant load exercise VO2 kinetics study in the evaluation of heart failure." American Journal of Hypertension 16, no. 5 (May 2003): A86. http://dx.doi.org/10.1016/s0895-7061(03)00295-4.

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Algul, S., F. A. Ugur, A. Ayar, and O. Ozcelik. "Comparative determination of ventilatory efficiency from constant load and incremental exercise testing." Cellular and Molecular Biology 63, no. 7 (August 15, 2017): 26. http://dx.doi.org/10.14715/cmb/2017.63.7.4.

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Orok, C. J., R. L. Hughson, H. J. Green, and J. A. Thomson. "Blood lactate responses in incremental exercise as predictors of constant load performance." European Journal of Applied Physiology and Occupational Physiology 59, no. 4 (November 1989): 262–67. http://dx.doi.org/10.1007/bf02388326.

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Henson, Lindsey C., David C. Poole, and Brian J. Whipp. "Fitness as a determinant of oxygen uptake response to constant-load exercise." European Journal of Applied Physiology and Occupational Physiology 59, no. 1-2 (September 1989): 21–28. http://dx.doi.org/10.1007/bf02396575.

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McGuire, S., E. J. Horton, D. Renshaw, K. Chan, N. Krishnan, and G. McGregor. "Ventilatory and chronotropic incompetence during incremental and constant load exercise in end-stage renal disease: a comparative physiology study." American Journal of Physiology-Renal Physiology 319, no. 3 (September 1, 2020): F515—F522. http://dx.doi.org/10.1152/ajprenal.00258.2020.

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Maximal O2 uptake is impaired in end-stage renal disease (ESRD), reducing quality of life and longevity. While determinants of maximal exercise intolerance are well defined, little is known of limitation during submaximal constant load exercise. By comparing individuals with ESRD and healthy controls, the aim of this exploratory study was to characterize mechanisms of exercise intolerance in participants with ESRD by assessing cardiopulmonary physiology at rest and during exercise. Resting spirometry and echocardiography were performed in 20 dialysis-dependent participants with ESRD (age: 59 ± 12 yr, 14 men and 6 women) and 20 healthy age- and sex-matched controls. Exercise tolerance was assessed with ventilatory gas exchange and central hemodynamics during a maximal cardiopulmonary exercise test and 30 min of submaximal constant load exercise. Left ventricular mass (292 ± 102 vs. 185 ± 83 g, P = 0.01) and filling pressure ( E/ e′: 6.48 ± 3.57 vs. 12.09 ± 6.50 m/s, P = 0.02) were higher in participants with ESRD; forced vital capacity (3.44 ± 1 vs. 4.29 ± 0.95 L/min, P = 0.03) and peak O2 uptake (13.3 ± 2.7 vs. 24.6 ± 7.3 mL·kg−1·min−1, P < 0.001) were lower. During constant load exercise, the relative increase in the arterial-venous O2 difference (13 ± 18% vs. 74 ± 18%) and heart rate (32 ± 18 vs. 75 ± 29%) were less in participants with ESRD despite exercise being performed at a higher percentage of maximum minute ventilation (48 ± 3% vs. 39 ± 3%) and heart rate (82 ± 2 vs. 64 ± 2%). Ventilatory and chronotropic incompetence contribute to exercise intolerance in individuals with ESRD. Both are potential targets for medical and lifestyle interventions.

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Yamazaki, F., R. Sone, and H. Ikegami. "Responses of sweating and body temperature to sinusoidal exercise." Journal of Applied Physiology 76, no. 6 (June 1, 1994): 2541–45. http://dx.doi.org/10.1152/jappl.1994.76.6.2541.

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This study determined the phase response and amplitude response (delta) of esophageal temperature (T(es)), mean skin temperature (Tsk), and forearm sweating rate (Msw) to sinusoidal work. Six healthy male subjects exercised on a cycle ergometer with a constant load (approximately 35% maximal O2 uptake) for a 30-min period; for the next 40 min they exercised with a sinusoidal load at 25 degrees C at 35% relative humidity. The sinusoidal load varied between approximately 10 and 60% maximal O2 uptake, and three different time periods (1.3, 4, and 8 min) were selected. Each subject performed three experiments that differed only in the timing of sinusoidal work. During the 4- and 8-min periods, T(es), Tsk, and Msw changed almost sinusoidally. The phase of Msw change significantly preceded those of T(es) and Tsk changes (P < 0.05). During the 1.3-min period, the level of T(es) and Tsk remained almost constant (delta T(es) 0.01 +/- 0.00 degrees C, delta Tsk 0.03 +/- 0.01 degrees C), whereas Msw showed a clear sinusoidal pattern. We conclude that the sweating response during sinusoidal work depends on both thermal and nonthermal factors, the latter being emotional, mental, or sensory stimulation. The contribution of the nonthermal factors to the general sweating response during exercise can be separated from that of the thermal factors by using sinusoidal work during a short period (e.g., 1.3 min).

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Heck, Kristen L., Jeffrey A. Potteiger, Karen L. Nau, and Jan M. Schroeder. "Sodium Bicarbonate Ingestion Does Not Attenuate the VO2 Slow Component during Constant-Load Exercise." International Journal of Sport Nutrition 8, no. 1 (March 1998): 60–69. http://dx.doi.org/10.1123/ijsn.8.1.60.

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We examined the effects of sodium bicarbonate ingestion on the VO2 slow component during constant-load exercise. Twelve physically active males performed two 30-min cycling trials at an intensity above the lactate threshold. Subjects ingested either sodium bicarbonate (BIC) or placebo (PLC) in a randomized. counterbalanced order. Arterialized capillary blood samples were analyzed for pH, bicarbonate concentration ([HCO3−), and lactate concentration ([La]). Expired gas samples were analyzed for oxygen consumption (VO2). The VO2 slow component was defined as the change in VO2 from Minutes 3 and 4 to Minutes 28 and 29. Values for pH and [HCO3−] were significantly higher for BIC compared to PLC. There was no significant difference in [La] between conditions. For both conditions there was a significant time effect for VO2 during exercise: however, no significant difference was observed between BIC and PLC. While extracellular acid-base measures were altered during the BIC trial, sodium bicarbonate ingestion did not attenuate the VO2 slow component during constant-load exercise.

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Okawara, Hiroki, Tomonori Sawada, Daisuke Nakashima, Yuta Maeda, Shunsuke Minoji, Takashi Morisue, Yoshinori Katsumata, Morio Matsumoto, Masaya Nakamura, and Takeo Nagura. "Realtime Monitoring of Local Sweat Rate Kinetics during Constant-Load Exercise Using Perspiration-Meter with Airflow Compensation System." Sensors 22, no. 15 (July 22, 2022): 5473. http://dx.doi.org/10.3390/s22155473.

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Epidermal wearable sweat biomarker sensing technologies are likely affected by sweat rate because of the dilution effect and limited measurement methods. However, there is a dearth of reports on the local sweat rate (LSR) monitored in real-time during exercise. This explorative study investigated the feasibility of real-time LSR monitoring and clarified LSR kinetics on the forehead and upper arm during constant-load exercise using a perspiration meter with an airflow compensation system. This observational cross-sectional study included 18 recreationally trained males (mean age, 20.6 ± 0.8 years). LSR on the forehead and upper arm (mg/cm2/min) were measured during a constant-load exercise test at 25% of their pre-evaluated peak power until exhaustion. The LSR kinetics had two inflection points, with a gradual decrease in the incremental slope for each section. After the second flexion point, the LSR slope slightly decreased and was maintained until exhaustion. However, the degree of change varied among the participants. Although the ratio of forehead LSR to upper arm LSR tended to decrease gradually over time, there was little change in this ratio after a second flexion point of LSR in both. These findings suggest possible differences in LSR control between the forehead and upper arm during constant-load exercise to prolonged exhaustion.

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VITTORI, L. N., D. N. MANNERS, G. BELLI, I. CORAZZA, and P. MAIETTA LATESSA. "A RAPID AND AUTOMATED METHOD TO DETERMINE APPROPRIATE EXERCISE PARAMETERS FOR TAILORED SUBSTRATE CONSUMPTION DURING AEROBIC EXERCISE." Journal of Mechanics in Medicine and Biology 15, no. 02 (April 2015): 1540038. http://dx.doi.org/10.1142/s0219519415400382.

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The growing prevalence of obesity and metabolic disorders such as type II diabetes, is associated with reduced exercise and maximal fat oxidation rate (Fatmax). The aim of this study was to verify the reliability of a new test protocol (Fatmaxwork) using the INCA software package. Twenty four sedentary subjects was enrolled and performed the following tests using a VO2000 metabolimeter: (1) An incremental test of 20 min to determine the individual Fatmax and maximum rate of fat oxidation (MFO) with new Fatmaxwork test; (2) a constant load test of 60 min. For our subjects, the average fat zone was estimated by INCA at 54.2 ± 4.9% max HR, RER 0.86 ± 0.09, 130 ± 64 W. The results from the constant load test differed by 0.01 ± 1.92 for respiratory gas exchange rate (RER) and -0.22 ± 1.92% for heart rate (HR). This study showed that the Fatmaxwork test can be used to predict Fatmax in untrained overweight subjects and INCA is a reliable and accurate software package.

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Mettauer, Bertrand, Quan Ming Zhao, Eric Epailly, Anne Charloux, Eliane Lampert, Bernadette Heitz-Naegelen, François Piquard, Pietro E. di Prampero, and Jean Lonsdorfer. "V˙o 2 kinetics reveal a central limitation at the onset of subthreshold exercise in heart transplant recipients." Journal of Applied Physiology 88, no. 4 (April 1, 2000): 1228–38. http://dx.doi.org/10.1152/jappl.2000.88.4.1228.

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Because the cardiocirculatory response of heart transplant recipients (HTR) to exercise is delayed, we hypothesized that their O2 uptake (V˙o 2) kinetics at the onset of subthreshold exercise are slowed because of an impaired early “cardiodynamic” phase 1, rather than an abnormal subsequent “metabolic” phase 2. Thus we compared the V˙o 2 kinetics in 10 HTR submitted to six identical 10-min square-wave exercises set at 75% (36 ± 5 W) of the load at their ventilatory threshold (VT) to those of 10 controls (C) similarly exercising at the same absolute (40 W; C40W group) and relative load (67 ± 14 W; C67W group). Time-averaged heart rate, breath-by-breathV˙o 2, and O2pulse (O2p) data yielded monoexponential time constants of the V˙o 2 (s) and O2p increase. Separating phase 1 and 2 data permitted assessment of the phase 1 duration and phase 2 V˙o 2 time constant ([Formula: see text]). The V˙o 2 time constant was higher in HTR (38.4 ± 7.5) than in C40W (22.9 ± 9.6; P ≤ 0.002) or C67W (30.8 ± 8.2; P ≤ 0.05), as was the O2p time constant, resulting from a lower phase 1V˙o 2 increase (287 ± 59 vs. 349 ± 66 ml/min; P ≤ 0.05), O2p increase (2.8 ± 0.6 vs. 3.6 ± 1.0 ml/beat; P ≤ 0.0001), and a longer phase 1 duration (36.7 ± 12.3 vs. 26.8 ± 6.0 s; P≤ 0.05), whereas the[Formula: see text]was similar in HTR and C (31.4 ± 9.6 vs. 29.9 ± 5.6 s; P = 0.85). Thus the HTR have slower subthresholdV˙o 2 kinetics due to an abnormal phase 1, suggesting that the heart is unable to increase its output abruptly when exercise begins. We expected a faster[Formula: see text]in HTR because of their prolonged phase 1 duration. Because this was not the case, their muscular metabolism may also be impaired at the onset of subthreshold exercise.

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Plotkin, Daniel, Max Coleman, Derrick Van Every, Jaime Maldonado, Douglas Oberlin, Michael Israetel, Jared Feather, Andrew Alto, Andrew D. Vigotsky, and Brad J. Schoenfeld. "Progressive overload without progressing load? The effects of load or repetition progression on muscular adaptations." PeerJ 10 (September 30, 2022): e14142. http://dx.doi.org/10.7717/peerj.14142.

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Background Progressive overload is a principle of resistance training exercise program design that typically relies on increasing load to increase neuromuscular demand to facilitate further adaptations. However, little attention has been given to another way of increasing demand—increasing the number of repetitions. Objective This study aimed to compare the effects of two resistance training programs: (1) increasing load while keeping repetition range constant vs (2) increasing repetitions while keeping load constant. We aimed to compare the effects of these programs on lower body muscle hypertrophy, muscle strength, and muscle endurance in resistance-trained individuals over an 8-week study period. Methods Forty-three participants with at least 1 year of consistent lower body resistance training experience were randomly assigned to one of two experimental, parallel groups: A group that aimed to increase load while keeping repetitions constant (LOAD: n = 22; 13 men, nine women) or a group that aimed to increase repetitions while keeping load constant (REPS: n = 21; 14 men, seven women). Subjects performed four sets of four lower body exercises (back squat, leg extension, straight-leg calf raise, and seated calf raise) twice per week. We assessed one repetition maximum (1RM) in the Smith machine squat, muscular endurance in the leg extension, countermovement jump height, and muscle thickness along the quadriceps and calf muscles. Between-group effects were estimated using analyses of covariance, adjusted for pre-intervention scores and sex. Results Rectus femoris growth modestly favored REPS (adjusted effect estimate (CI90%), sum of sites: 2.8 mm [−0.5, 5.8]). Alternatively, dynamic strength increases slightly favored LOAD (2.0 kg [−2.4, 7.8]), with differences of questionable practical significance. No other notable between-group differences were found across outcomes (muscle thicknesses, <1 mm; endurance, <1%; countermovement jump, 0.1 cm; body fat, <1%; leg segmental lean mass, 0.1 kg), with narrow CIs for most outcomes. Conclusion Both progressions of repetitions and load appear to be viable strategies for enhancing muscular adaptations over an 8-week training cycle, which provides trainers and trainees with another promising approach to programming resistance training.

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Louvaris, Zafeiris, Nikolaos Chynkiamis, Stavroula Spetsioti, Andreas Asimakos, Spyros Zakynthinos, Peter D. Wagner, and Ioannis Vogiatzis. "Greater exercise tolerance in COPD during acute interval, compared to equivalent constant‐load, cycle exercise: physiological mechanisms." Journal of Physiology 598, no. 17 (June 16, 2020): 3613–29. http://dx.doi.org/10.1113/jp279531.

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Miki, Keisuke, Kazuyuki Tsujino, Mari Miki, Kenji Yoshimura, Hiroyuki Kagawa, Yohei Oshitani, Kiyoharu Fukushima, Takanori Matsuki, Yuji Yamamoto, and Hiroshi Kida. "Managing COPD with expiratory or inspiratory pressure load training based on a prolonged expiration pattern." ERJ Open Research 6, no. 3 (July 2020): 00041–2020. http://dx.doi.org/10.1183/23120541.00041-2020.

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BackgroundExertional prolonged expiration should be identified as a therapeutic target in COPD. The efficacy of expiratory or inspiratory pressure load training (EPT/IPT) based on the degree of prolonged expiration was investigated.MethodsA total of 21 patients with COPD were divided into two groups according to the exertional change in the inspiratory duty cycle (TI/Ttot). For 12 weeks, patients whose exertional TI/Ttot decreased received EPT (EPT group, n=11, mean percentage forced expiratory volume in 1 s (%FEV1), 32.8%) and those whose exertional TI/Ttot increased received IPT (IPT group, n=10, mean %FEV1, 45.1%).ResultsThe therapeutic responses were as follows. In both groups, endurance time (EPT, +5.7 min, p<0.0001; IPT, +6.1 min, p=0.0004) on the constant work rate exercise test (WRET) and peak oxygen uptake increased (EPT, p=0.0028; IPT, p=0.0072). In the EPT group the following occurred: 1) soon after commencement of exercise with the constant WRET, the expiratory tidal volume (VTex) increased, reducing dyspnoea; 2) VTex and mean expiratory flow increased and then prolonged expiration (p=0.0001) improved at peak exercise with the incremental exercise test (ET); and 3) St. George's Respiratory Questionnaire total, activity and impact scores were improved. In the IPT group, on both the constant WRET and incremental ET, breathing frequency increased, which led to greater exercise performance with effort dyspnoea.ConclusionsThis study showed the benefits of EPT/IPT on exercise performance. If the choice of managing COPD with EPT/IPT is appropriate, inexpensive EPT/IPT may become widespread as home-based training.

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NAKAMURA, YOSHIO, ETSUMORI ONDA, and ISAO MURAOKA. "EXCESS CO₂ OUTPUT INDEPENDENT OF HYPERVENTILATION DURING CONSTANT-LOAD EXERCISE." Japanese Journal of Physical Fitness and Sports Medicine 40, no. 5 (1991): 437–46. http://dx.doi.org/10.7600/jspfsm1949.40.437.

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Mizuo, Jun, Takaaki Nakatsu, Takashi Murakami, Shozo Kusachi, Youkou Tominaga, Keiichi Mashima, Tadahisa Uesugi, Hisashi Ueda, Chisato Suezawa, and Takao Tsuji. "Exponential Hyperbolic Sine Function Fitting of Heart Rate Response to Constant Load Exercise." Japanese Journal of Physiology 50, no. 4 (2000): 405–12. http://dx.doi.org/10.2170/jjphysiol.50.405.

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Arimitsu, T., R. Matsuura, T. Yunoki, R. Yamanaka, T. Kimura, CS Lian, R. Afroundeh, and T. Yano. "Relationship between oxygen uptake and oxygen supply system during constant-load supine exercise." Biology of Sport 27, no. 3 (September 30, 2010): 151–56. http://dx.doi.org/10.5604/20831862.919330.

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Heck, K. L., J. A. Potteiger, K. L. Nau, and J. M. Schroeder. "INDUCED ALKALOSIS DOES NOT ATTENUATE THE OXYGEN DRIFT DURING CONSTANT-LOAD EXERCISE 1082." Medicine &amp Science in Sports &amp Exercise 28, Supplement (May 1996): 182. http://dx.doi.org/10.1097/00005768-199605001-01080.

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