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Does oxygen delivery explain interindividual variation in forearm critical impulse?

Kellawan JM, Bentley RF, Bravo MF, Moynes JS, Tschakovsky ME - Physiol Rep (2014)

Bottom Line: Both vasodilation (r(2) = 0.64, P < 0.001) and the exercise pressor response (r(2) = 0.33, P < 0.001) independently contributed to interindividual differences in FBF.Furthermore, individual differences in pressor response play an important role in determining differences in O2 delivery in addition to vasodilation.The mechanistic origins of this vasodilatory and pressor response heterogeneity across individuals remain to be determined.

View Article: PubMed Central - PubMed

Affiliation: Department of Kinesiology, School of Education, University of Wisconsin, Madison, Wisconsin.

No MeSH data available.


Related in: MedlinePlus

Relationship between maximal voluntary contraction (MVC) and forearm critical impulse in healthy male subjects. Data pooled over multiple studies from our laboratory. Individual study data is identified in the legend. Regression line: Critical Impulse = 123.404 + (0.215 MVC), r2 = 0.125, P = 0.015.
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fig02: Relationship between maximal voluntary contraction (MVC) and forearm critical impulse in healthy male subjects. Data pooled over multiple studies from our laboratory. Individual study data is identified in the legend. Regression line: Critical Impulse = 123.404 + (0.215 MVC), r2 = 0.125, P = 0.015.

Mentions: O2 delivery during the maximal effort test varied substantially between subjects (O2 delivery AUC range 533–1231 mL·O2, plateau in O2 delivery 73.59–154.10 mL O2·min−1) as did critical impulse (381.5–584.8 N). Forward stepwise regression of O2 delivery plateau and forearm characteristics against critical impulse identified O2 delivery as a strong predictor of critical impulse (O2 delivery r = 0.92, r2 = 0.85, P < 0.001), whereas forearm characteristics fell out of the model as they had no relationship with critical impulse (MVC P = 0.969, forearm volume P = 0.639, forearm girth P = 0.381) The O2 delivery AUC was also a strong predictor, explaining 77% of the variance in critical impulse when regressed separately (O2 delivery AUC r = 0.88, r2 = 0.77, P < 0.01) (Fig. 1A and B). In contrast, the ΔO2 delivery from baseline accounted for only 66% of the variance in critical impulse. Furthermore, while forearm volume was significantly correlated with MVC (r2 = 0.42, P = 0.04) forearm girth was not (r2 = 0.06, P = 0.48). However, addition of subjects from previously published studies (Moynes et al. 2013; Kellawan and Tschakovsky 2014) as well as unpublished data from ongoing investigations increasing the total n to 47 identified a weak, albeit statistically significant,, relationship between critical impulse and MVC (Fig. 2; r2 = 0.125, P = 0.015).


Does oxygen delivery explain interindividual variation in forearm critical impulse?

Kellawan JM, Bentley RF, Bravo MF, Moynes JS, Tschakovsky ME - Physiol Rep (2014)

Relationship between maximal voluntary contraction (MVC) and forearm critical impulse in healthy male subjects. Data pooled over multiple studies from our laboratory. Individual study data is identified in the legend. Regression line: Critical Impulse = 123.404 + (0.215 MVC), r2 = 0.125, P = 0.015.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4255810&req=5

fig02: Relationship between maximal voluntary contraction (MVC) and forearm critical impulse in healthy male subjects. Data pooled over multiple studies from our laboratory. Individual study data is identified in the legend. Regression line: Critical Impulse = 123.404 + (0.215 MVC), r2 = 0.125, P = 0.015.
Mentions: O2 delivery during the maximal effort test varied substantially between subjects (O2 delivery AUC range 533–1231 mL·O2, plateau in O2 delivery 73.59–154.10 mL O2·min−1) as did critical impulse (381.5–584.8 N). Forward stepwise regression of O2 delivery plateau and forearm characteristics against critical impulse identified O2 delivery as a strong predictor of critical impulse (O2 delivery r = 0.92, r2 = 0.85, P < 0.001), whereas forearm characteristics fell out of the model as they had no relationship with critical impulse (MVC P = 0.969, forearm volume P = 0.639, forearm girth P = 0.381) The O2 delivery AUC was also a strong predictor, explaining 77% of the variance in critical impulse when regressed separately (O2 delivery AUC r = 0.88, r2 = 0.77, P < 0.01) (Fig. 1A and B). In contrast, the ΔO2 delivery from baseline accounted for only 66% of the variance in critical impulse. Furthermore, while forearm volume was significantly correlated with MVC (r2 = 0.42, P = 0.04) forearm girth was not (r2 = 0.06, P = 0.48). However, addition of subjects from previously published studies (Moynes et al. 2013; Kellawan and Tschakovsky 2014) as well as unpublished data from ongoing investigations increasing the total n to 47 identified a weak, albeit statistically significant,, relationship between critical impulse and MVC (Fig. 2; r2 = 0.125, P = 0.015).

Bottom Line: Both vasodilation (r(2) = 0.64, P < 0.001) and the exercise pressor response (r(2) = 0.33, P < 0.001) independently contributed to interindividual differences in FBF.Furthermore, individual differences in pressor response play an important role in determining differences in O2 delivery in addition to vasodilation.The mechanistic origins of this vasodilatory and pressor response heterogeneity across individuals remain to be determined.

View Article: PubMed Central - PubMed

Affiliation: Department of Kinesiology, School of Education, University of Wisconsin, Madison, Wisconsin.

No MeSH data available.


Related in: MedlinePlus