Open AccessExercise tolerance through severe and extreme intensity domains
Author(s) -
Alexander Andrew M.,
Didier Kaylin D.,
Hammer Shane M.,
Dzewaltowski Alex C.,
Kriss Karly N.,
Lovoy Garrett M.,
Hammer Joseph L.,
Smith Joshua R.,
Ade Carl J.,
Broxterman Ryan M.,
Barstow Thomas J.
Publication year - 2019
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.14014
Subject(s) - intensity (physics) , exercise intensity , cardiology , limiting , medicine , mathematics , physical therapy , heart rate , physics , blood pressure , quantum mechanics , mechanical engineering , engineering
The power‐duration relationship accurately predicts exercise tolerance for constant power exercise performed in the severe intensity domain. However, the accuracy of the prediction of time to task failure ( T lim ) is currently unclear for work rates ( WR ) above severe intensities; that is, within the extreme intensity domain ( T lim < 2 min). We hypothesized that T lim would be shorter for WR s within the extreme intensity domain than predicted from the linear 1/time relationship of the severe intensity domain which would suggest mechanisms limiting exercise are different between intensity domains. Six men completed 7 knee‐extension tests. T lim of extreme intensity exercise (60%, 70%, 80%, and 90% 1 RM ; T lim < 2 min) were compared to the predicted T lim from the slope of the S1–S3 ( T lim ≥ 2–15 min) regression. Twitch force ( Q tw ) and maximal voluntary contraction ( MVC ) were measured on the right vastus lateralis before and after each test. T lim at 70–90% 1 RM were shorter than the T lim predicted by the severe domain 1/time model ( P < 0.05); however, T lim at 60% 1 RM was not different than the predicted severe T lim , suggesting the mechanisms limiting extreme exercise manifest ≥60% 1 RM . A significant linear relationship for 60–90% 1 RM was observed which suggested a curvature constant unique to the extreme domain ( W ext ′ ) that was smaller than the W ′ of the severe domain (1.5 ± 0.6 vs. 5.9 ± 1.5 kJ , P < 0.001). Q tw and MVC were significantly decreased following severe exercise, however, Q tw and MVC were not significantly decreased following 80% and 90% 1 RM , giving evidence that mechanisms causing task failure were recovered by the time post‐exercise measurements were made (~90 sec).