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201. Reduction of V̇O2 slow component by priming exercise: novel mechanistic insights from time-resolved near-infrared spectroscopy.

Author

Fukuoka, Yoshiyuki, Poole, David C., Barstow, Thomas J., Kondo, Narihiko, Nishiwaki, Masato, Okushima, Dai, and Koga, Shunsaku

Subjects
NEAR infrared spectroscopy, MICROCIRCULATION, ADIPOSE tissue physiology, ANAEROBIC threshold, DEOXYHEMOGLOBIN
Abstract

Novel time-resolved near-infrared spectroscopy ( TR- NIRS), with adipose tissue thickness correction, was used to test the hypotheses that heavy priming exercise reduces the V̇O2 slow component (V̇O2SC) (1) by elevating microvascular [Hb] volume at multiple sites within the quadriceps femoris (2) rather than reducing the heterogeneity of muscle deoxygenation kinetics. Twelve subjects completed two 6-min bouts of heavy work rate exercise, separated by 6 min of unloaded cycling. Priming exercise induced faster overall V̇O2 kinetics consequent to a substantial reduction in the V̇O2SC (0.27 ± 0.12 vs. 0.11 ± 0.09 L·min−1, P < 0.05) with an unchanged primary V̇O2 time constant. An increased baseline for the primed bout [total (Hb + Mb)] (197.5 ± 21.6 vs. 210.7 ± 22.5 μmol L−1, P < 0.01), reflecting increased microvascular [Hb] volume, correlated significantly with the V̇O2SC reduction. At multiple sites within the quadriceps femoris, priming exercise reduced the baseline and slowed the increase in [deoxy (Hb + Mb)]. Changes in the intersite coefficient of variation in the time delay and time constant of [deoxy (Hb + Mb)] during the second bout were not correlated with the V̇O2SC reduction. These results support a mechanistic link between priming exercise-induced increase in muscle [Hb] volume and the reduced V̇O2SC that serves to speed overall V̇O2 kinetics. However, reduction in the heterogeneity of muscle deoxygenation kinetics does not appear to be an obligatory feature of the priming response. [ABSTRACT FROM AUTHOR]

Published
2015
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221. Spectral and bout detection analysis of physical activity patterns in healthy, prepubertal boys and girls.

Author

Berman, Nancy, Berman, Nancy, Bailey, Robert, Barstow, Thomas J, Cooper, Dan M, Berman, Nancy, Berman, Nancy, Bailey, Robert, Barstow, Thomas J, and Cooper, Dan M

Abstract

Little is known about the frequency-intensity patterns of naturally occurring physical activity in children. A data set obtained previously by direct observation of physical activity in 8 girls and 7 boys (all prepubertal, ages 6-10) was analyzed with spectral analysis to detect significant frequency-intensity relationships. Pulse detection algorithms were used to characterize the number of exercise bouts, their duration and relative intensity. Spectral analysis revealed that physical activity bouts were frequent, pulsatile, and random with no significant frequencies detected during many 24-min periods of observation. An average of 83 ± 11 bouts per hour were observed in boys and 89 ± 12 bouts per hour in girls, and the mean duration of an exercise bout was 21 ± 5 sec for boys and 20 ± 4 sec for girls (NS). While high-intensity exercise bouts comprised less than 20% of the time spent in physical activity, duration of high intensity exercise bouts tended to be longer and accounted for about 40% of the energy expenditure associated with physical activity. Spontaneous physical activity in prepubertal children is characterized by frequent bouts of brief, mostly low intensity exercise, randomly interspersed with less frequent, but metabolically substantial high intensity bouts. These findings are potentially useful in assessing the impact of disease on quality of life in children, investigating the relationship between physical activity and mechanisms of growth and development, and creating new approaches for in-laboratory exercise testing in children. Am. J. Hum. Biol. 10:289-297, 1998. © 1998 Wiley-Liss, Inc.

Published
1998

231. The critical power concept in all-out isokinetic exercise.

Author

Dekerle, Jeanne, Barstow, Thomas J., Regan, Luke, and Carter, Helen

Abstract

The critical power concept has been applied to constant-load exhaustive exercise and recently validated for 3-min all-out exercise. Objectives To test the application of critical power to a 3-min all-out isokinetic cycling exercise. Design Single-group, experimental, comparative design. Method Nine participants performed a 3-min all-out isokinetic test and 4-5 constant-load exhaustive trials, at 60 and 100rpm, on an electrically-braked cycle. The linear P-t-1 relationship was modelled using a 2-parameter model (slope: critical power; intercept: Anaerobic Work Capacity). End power and accumulated work done above EP were calculated from the 3-min tests. Results No significant difference and a significant correlation was found between end power and critical power (60rpm: 259±40W vs. 245±38W, P>0.05; r=0.85, P<0.01; 100rpm: 227±57W vs. 212±44W, P>0.05; r=0.86, P<0.01). The Bias±95% limits of agreement were 14±42W at 60rpm and 15±57W at 100rpm. Work done above EP (60rpm: 14.7±3.0kJ; 100rpm: 17.3±3.1kJ) was not significantly different to the anaerobic work capacity (60rpm: 16.2±3.2kJ; 100rpm: 20.6±6.4kJ; P>0.05) but with only a significant correlation at 60rpm (r=-0.71, P<0.05). Conclusions The 2-parameter model underpinning the critical power construct can be applied to a 3-min all-out isokinetic test. End power does not differ and correlates with critical power. However, a further insight into levels of agreement leads to some scepticism concerning the use of the two variables interchangeably. The great intra-subject differences between work done above EP and the intercept of the P-t-1 relationship should also be considered. [ABSTRACT FROM AUTHOR]

Published
2014
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245. &OV0312;O2 slow component

Author

POOLE, DAVID C., primary, BARSTOW, THOMAS J., additional, GAESSER, GLENN A., additional, WILLIS, WAYNE T., additional, and WHIPP, BRIAN J., additional

Published
1994
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246. O2 Uptake Kinetics in Response to Exercise

Author

Zhang, Yong Yu, primary, Wasserman, Karlman, additional, Sietsema, Kathy E., additional, Ben-Dov, Issahar, additional, Barstow, Thomas J., additional, Mizumoto, Grace, additional, and Sullivan, Cynthia S., additional

Published
1993
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248. Characterizing near-infrared spectroscopy responses to forearm post-occlusive reactive hyperemia in healthy subjects.

Author

Bopp, Christopher, Townsend, Dana, Barstow, Thomas, Bopp, Christopher M, Townsend, Dana K, and Barstow, Thomas J

Subjects
NEAR infrared spectroscopy, HYPEREMIA, HEMOGLOBINS, MYOGLOBIN, EXPONENTIAL functions, ANALYSIS of variance, BRACHIAL artery, OXYGEN analysis, CLINICAL trials, COMPARATIVE studies, EXERCISE tests, FOREARM, HEALTH, RESEARCH methodology, MEDICAL cooperation, RADIOGRAPHY, RESEARCH, TIME, ULTRASONIC imaging, EVALUATION research, PHYSIOLOGY
Abstract

During post-occlusive reactive hyperemia (PORH) there is a temporary increase in the total hemoglobin + myoglobin (T[Hb+Mb]) signal as measured by near-infrared spectroscopy (NIRS). This transient increase predicts differences in the kinetic responses of deoxy[Hb+Mb] and oxy[Hb+Mb] during PORH. The purpose of this study was to determine whether sigmoidal (Gompertz or logistic) or exponential functions better describe these response curves during PORH. The fit of the three functions (exponential, Gompertz and logistic) to the NIRS responses, as determined from residual sum of squares, was compared using repeated measures ANOVA on Ranks. The Gompertz function provided a better fit to the oxy[Hb+Mb] response curve than did either the exponential or logistic function (χ (2) = 21.7, df = 2, p < 0.001). The logistic function provided a better fit for the deoxy[Hb+Mb] response (χ (2) = 22.9, df = 2, p < 0.001) than did either the Gompertz or exponential functions. For both NIRS signals, the better fitting sigmoidal functions fit the data well, with an average r value of 0.99 or greater. Adipose tissue thickness was correlated with parameters related to signal strength (amplitude, r = 0.86-0.89; baseline, r = 0.67-0.75; all p < 0.001) but was not related to kinetic parameters (time constant and inflection point; p > 0.05 for all comparisons). These results suggest that during PORH distinct sigmoidal mathematical functions best describe the responses of the oxy[Hb+Mb] (Gompertz) and deoxy[Hb+Mb] (logistic) as measured by NIRS. Further, differences in both the kinetic and amplitude aspects for the responses of oxy[Hb+Mb] and deoxy[Hb+Mb] predict the observed transient change in T[Hb+Mb]. Our methods provide a technique to evaluate and quantify NIRS responses during PORH, which may have clinical utility. [ABSTRACT FROM AUTHOR]

Published
2011
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