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151 results on '"Cochrane, Kristen"'

24. The Effects of Work-to-Rest Ratios on Torque, Electromyographic, and Mechanomyographic Responses to Fatiguing Workbouts

Author

HILL, ETHAN C., HOUSH, TERRY J., SMITH, CORY M., COCHRANE, KRISTEN C., JENKINS, NATHANIEL D.M., SCHMIDT, RICHARD J., and JOHNSON, GLEN O.

Subjects
alternating rest, Neuromuscular fatigue, EMG, muscle fatigue, MMG, Original Research
Abstract

The purpose of the present study was to examine the effects of 2 different work-to-rest ratios, but the same mean load, cycle time, and total duration of the exercise bout, on maximal voluntary isometric contraction torque and neuromuscular responses to fatiguing, intermittent, submaximal, isometric, forearm flexion muscle actions. Ten men performed 2 fatiguing protocols with different work-to-rest ratios (4 s contraction, 4 s rest vs. 4 s contraction, alternating 6 and 2 s rest) that consisted of 50 intermittent, submaximal (65% of maximal voluntary isometric contraction), isometric, forearm flexion muscle actions. Electromyographic and mechanomyographic signals from the biceps brachii were recorded before, during, immediately and 5 min after performing the fatiguing protocols. In addition, maximal voluntary isometric contraction torque was assessed before, immediately and 5 min after. Both protocols resulted in decreases in maximal voluntary isometric contraction torque, electromyographic mean power frequency, and mechanomyographic mean power frequency, but no changes in electromyographic amplitude or mechanomyographic amplitude. The results of the present study indicated that differences in work-to-rest ratio did not affect maximal voluntary isometric contraction torque or the associated neuromuscular parameters as a result of fatiguing, intermittent, isometric muscle actions when mean load, cycle time, and total duration of exercise were equivalent.

Published
2017

25. Physiological responses at the rating of perceived exertion at and above the gas exchange threshold during treadmill running

Author

Cochrane, Kristen C and Cochrane, Kristen C

Abstract

The purposes of this study were to examine: 1) the metabolic, cardiovascular, respiratory, neuromuscular, and velocity responses during continuous, constant rating of .perceived exertion (RPE) runs at the RPE corresponding to the velocity at the gas exchange threshold (RPEGET) and 15% above GET (RPE GET+15%); and 2) the metabolic efficiency changes during continuous, constant RPE runs at RPEGET and RPEGET+15%. Eleven moderately trained runners performed an incremental treadmill test to exhaustion. GET and GET+15% were determined from the incremental test to exhaustion, and the velocity at GET and GET+15% were used to estimate the RPEGET and RPEGET+15% using linear regression. On separate days, subjects performed 60 min runs at RPEGET and RPEGET+15%, and physiological, neuromuscular, and perceptual responses were recorded. Polynomial regression analyses were used to examine the patterns of responses for all of the variables and paired-samples t-tests were used to determine changes in metabolic efficiency at RPEGET and RPEGET+15%. The results of the polynomial regression analyses indicated that there were negative, quadratic relationships (R2 = 0.96 – 0.99) for V˙ O2, RER, V˙ E, and velocity vs. time at RPEGET and RPEGET+15%; positive, quadratic relationships (R2 = 0.87 and 0.74) for Fb vs. time at RPEGET and RPEGET+15%; and positive, linear (r2 = 0.73), and no significant (r2 = 0.0) relationships for HR vs. time at RPEGET and RPEGET+15%, respectively. There were negative, linear relationships (r2 = 0.96 and 0.63) for VL and VM EMG RMS vs. time, and positive, linear relationships (r 2 = 0.72 and 0.40) for VL and VM EMG MPF vs. time at RPEGET. In addition, there was a negative, linear relationship (r2 = 0.16) for VL EMG RMS vs. time, a positive, quadratic relationship (R2 = 0.74) for VM EMG RMS vs. time, and positive, quadratic relationships (R 2 = 0.73 and 0.96) for VL and VM EMG MPF vs. time at RPEGET+15% . There were decreases in metabolic efficiency at RPEGET and R

Published
2016

27. Time Course of Changes in Neuromuscular Parameters During Sustained Isometric Muscle Actions

Author

Smith, Cory M., primary, Housh, Terry J., additional, Herda, Trent J., additional, Zuniga, Jorge M., additional, Camic, Clayton L., additional, Bergstrom, Haley C., additional, Smith, Doug B., additional, Weir, Joseph P., additional, Hill, Ethan C., additional, Cochrane, Kristen C., additional, Jenkins, Nathaniel D.M., additional, Schmidt, Richard J., additional, and Johnson, Glen O., additional

Published
2016
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36. Application of the Critical Heart Model to Treadmill Running

Author

Bergstrom, Haley C., primary, Housh, Terry J., additional, Cochrane, Kristen C., additional, Jenkins, Nathaniel D.M., additional, Buckner, Samuel L., additional, Goldsmith, Jacob A., additional, Zuniga, Jorge M., additional, Schmidt, Richard J., additional, Johnson, Glen O., additional, and Cramer, Joel T., additional

Published
2015
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40. Metabolic, Cardiovascular, and Perceptual Responses to a Thermogenic Nutritional Supplement at Rest, During Exercise, and Recovery in Men

Author

Bergstrom, Haley C., primary, Housh, Terry J., additional, Traylor, Daniel A., additional, Lewis, Robert W., additional, Cochrane, Kristen C., additional, Jenkins, Nathaniel D.M., additional, Schmidt, Richard J., additional, Johnson, Glen O., additional, Housh, Dona J., additional, and Cramer, Joel T., additional

Published
2014
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46. An examination of neuromuscular and metabolic fatigue thresholds

Author

Bergstrom, Haley C, primary, Housh, Terry J, additional, Cochrane, Kristen C, additional, Jenkins, Nathaniel D M, additional, Lewis, Robert W, additional, Traylor, Daniel A, additional, Zuniga, Jorge M, additional, Schmidt, Richard J, additional, Johnson, Glen O, additional, and Cramer, Joel T, additional

Published
2013
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49. Perceptual and Physiological Fatigue Thresholds during Cycle Ergometry.

Author

Cochrane, Kristen C., Housh, Terry J., Bergstrom, Haley C., Jenkins, Nathaniel D. M., Johnson, Glen O., Schmidt, Richard J., and Cramer, Joel T.

Subjects
DYNAMOMETER, EXERCISE intensity, OXYGEN consumption, FATIGUE (Physiology), THRESHOLD (Perception), HEART beat
Abstract

Thirteen subjects (mean ± SD age: 21.8 ± 2.6 yrs) performed an incremental cycling test and 4, 8-min submaximal rides (65 to 80% of VO2 peak) to: (a) compare power outputs and relative intensities that corresponded to the gas exchange threshold (GET), ventilatory threshold (VT), respiratory compensation point (RCP), physical working capacity (PWC) at oxygen consumption PWCVO2, heart rate (PWCHRT), and rating of perceived exertion (PWCOMNI) thresholds; and (b) examine the relationships among the fatigue thresholds and the exercise intensity domains. The RCP (184 ± 47 W) was significantly (P≤0.0033) greater than the GET (142 ± 38 W), VT (143 ± 40 W), PWCVO2 (106 ± 34 W), PWCHRT (108 ± 34 W), and PWCOMNI (112 ± 34 W). The GET and VT were significantly greater than the PWCVO2, PWCHRT, and PWCOMNI, but there were no differences among the PWCVO2, PWCHRT, and PWCOMNI. These findings suggest that the PWCVO2, PWCHRT, and PWCOMN fell within the moderate intensity domain, and share a common physiological mechanism that was different from those associated with the GET, VT, and RCP. [ABSTRACT FROM AUTHOR]

Published
2014

50. EFFECTS OF 6 WEEKS OF AEROBIC EXERCISE COMBINED WITH CONJUGATED LINOLEIC ACID ON THE PHYSICAL WORKING CAPACITY AT FATIGUE THRESHOLD.

Author

M. JENKINS, NATHANIEL D., BUCKNER, SAMUEL L., BAKER, ROBERT B., BERGSTROM, HALEY C., COCHRANE, KRISTEN C., WEIR, JOSEPH P., HOUSH, TERRY J., and CRAMER, JOEL T.

Subjects
LINOLEIC acid, AEROBIC exercises, COMBINED modality therapy, CYCLING, ELECTROMYOGRAPHY, FATIGUE (Physiology), FATTY acids, MUSCLE strength testing, HEALTH outcome assessment, PLACEBOS, RESEARCH funding, T-test (Statistics), RANDOMIZED controlled trials, OXYGEN consumption, ERGOMETRY, BLIND experiment, DATA analysis software, THERAPEUTICS
Abstract

The article discusses research investigating the effects of conjugated linoleic acid (CLA) supplementation combined with six weeks of aerobic exercise training on the physical working capacity at the fatigue threshold (PWCFT), timed sit-ups, and the standing long jump in both trained and untrained men approximately 21 years of age. Topics include the health benefits of CLA, the effects of CLA on exercise performance in humans, and neuromuscular fatigue.

Published
2014
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