Exercise tolerance through severe and extreme intensity domains

Abstract

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 ( ) 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).

W′ reconstitution rate at different intensities above critical torque: the role of muscle size and maximal strength

“…In the present study, the mean T lim for KE at 60% MVC was 125 s. Thus, the 60% MVC intensity was likely bordering on the extreme intensity domain, while the 35% MVC was likely within the severe intensity domain for the KE exercise. This may account for the differences in the utilization and reconstitution of IET′ observed and is consistent with recent evidence that the torque-T lim relationships differ between severe and extreme intensity KE exercise domains, with ∼60% MVC being the point of demarcation (Alexander et al, 2019).…”

“…The boundary between the severe and extreme intensity domains has also been distinguished by T lim shorter or longer than 2 min (Alexander et al, 2019;Hill et al, 2002). In the present study, the mean T lim for KE at 60% MVC was 125 s. Thus, the 60% MVC intensity was likely bordering on the extreme intensity domain, while the 35% MVC was likely within the severe intensity domain for the KE exercise.…”

“…Consistent with this, the T lim during isometric muscle contractions is significantly greater for plantar flexor (PF) (301 s) than knee extensor (KE) (157 s) muscles, despite exercising at similar percentages of MVC (∼60%) (Abdalla et al, 2018). It has also been demonstrated that the hyperbolic torque-T lim relationships differ between the severe and extreme domains, with these relationships merging at ∼60% of maximal strength (Alexander et al, 2019).…”

Influence of blood flow occlusion on muscular recruitment and fatigue during maximal‐effort small muscle‐mass exercise

“…2015 c ; Alexander et al . 2019). Previous data suggest the degree of potentiation is decreased after two MVCs (Kufel et al .…”

“…MVC during neuromuscular function testing was determined as the greatest force attained prior to the superimposed muscle stimulation. Voluntary activation (VA) was calculated using doublet interpolation (Behm et al 1996) (Bigland-Ritchie et al 1986;Burnley et al 2012;Broxterman et al 2015c;Alexander et al 2019). Previous data suggest the degree of potentiation is decreased after two MVCs (Kufel et al 2002).…”