Power-Velocity and Power-Efficiency Implications in the Limitation of Ramp Incremental Cycle Ergometry: Reply to Morales-Alamo et al.

Ferguson, Carrie; Cannon, Daniel T.; Wylde, Lindsey A.; Benson, Alan P.; Rossiter, Harry B.

doi:10.1152/japplphysiol.01067.2015

Cited by 5 publications

(3 citation statements)

References 5 publications

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“…Whether a power reserve remains at the point of task failure during RI exercise is contentious (16,27), and its relationship to fatigue development has not been studied in detail. The mechanisms responsible for reductions in muscle force development leading to task failure can originate in peripheral sites within the exercising muscle and/or central sites associated with central motor output and spinal or supraspinal transmission proximal to the neuromuscular junction (1,2,10,18,28,32,36), but the extent to which these mechanisms influence the power reserve is unknown.…”

Section: Introductionmentioning

confidence: 99%

Power reserve following ramp-incremental cycling to exhaustion: implications for muscle fatigue and function

Hodgson

Keir

Copithorne

et al. 2018

Journal of Applied Physiology

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In ramp-incremental cycling exercise, some individuals are capable of producing power output (PO) in excess of that produced at their limit of tolerance (LoT) whereas others cannot. This study sought to describe the 1) prevalence of a "power reserve" within a group of young men ( n = 21; mean ± SD: age 25 ± 4 yr; V̇o 45 ± 8 ml·kg·min); and 2) muscle fatigue characteristics of those with and without a power reserve. "Power reserve" (ΔPReserve) was determined as the difference between peak PO achieved during a ramp-incremental test to exhaustion and maximal, single-leg isokinetic dynamometer power determined within 45 s of completing the ramp-incremental test. Between-group differences in pre- vs. postexercise changes in voluntary and electrically stimulated single-leg muscle force production measures (maximal voluntary contraction torque, voluntary activation, maximal isotonic velocity and isokinetic power; 1-, 10-, 50-Hz torque; and 10/50-Hz ratio), V̇o, and constant-PO cycling time-to-exhaustion also were assessed. Frequency distribution analysis revealed a dichotomy in the prevalence of a power reserve within the sample resulting in two groups: 1) "No Reserve" (NRES: power reserve <5%; n = 10) and 2) "Reserve" (RES: power reserve >15%; n = 11). At the LoT, all participants had achieved V̇o. Muscle fatigue was evident in both groups, although the NRES group had greater reductions ( P < 0.05) in 10-Hz peak torque (PT), 10/50 Hz ratio, and maximal velocity. Time to the LoT during the constant PO test was 22 ± 16% greater ( P < 0.05) in RES (116 ± 19 s; PO = 317 ± 52 W) than in NRES (90 ± 23 s; PO = 337 ± 71 W), despite similar ramp-incremental exercise durations and V̇o between groups. Compared with the RES group, the NRES group accrued greater peripheral muscle fatigue at the LoT, suggesting that the mechanisms contributing to exhaustion in a ramp-incremental protocol are not uniform. NEW & NOTEWORTHY This study demonstrates that the mechanisms associated with the limit of tolerance during ramp-incremental cycling exercise differ between those who are capable of generating power output in excess of that at exercise termination vs. those who are not. Those without a "power reserve" exhibit greater peripheral muscle fatigue and reduced muscle endurance, supporting the hypothesis that exhaustion occurs at a specific level of neuromuscular fatigue. In contrast, those with a power reserve likely are limited by other mechanisms.

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Section: Introductionmentioning

confidence: 99%

Power reserve following ramp-incremental cycling to exhaustion: implications for muscle fatigue and function

Hodgson

Keir

Copithorne

et al. 2018

Journal of Applied Physiology

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“…Thus, regardless of the significant demands placed on the ventilatory and cardiovascular systems during maximal whole-body exercise, at intolerance, the inability to voluntarily exceed the power demands of the RI exercise task in RI-50 and RI-25 seems to be ultimately consequent to muscle fatigue and its associated influence on muscle activation. This is despite submaximal motor-unit recruitment at the limit of RI exercise, meaning that some muscle fibers maintain a metabolic reserve that would be capable of supporting increased ATP turnover (and power generation), were participants capable of activating these fibers at intolerance (13,41,42).…”

Section: Discussionmentioning

confidence: 99%

Power Reserve at Intolerance in Ramp-Incremental Exercise Is Dependent on Incrementation Rate

Davies

Lyall

Benson

et al. 2021

Medicine &Amp; Science in Sports &Amp; Exercise

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IntroductionThe mechanism(s) of exercise intolerance at V˙O2max remain poorly understood. In health, standard ramp-incremental (RI) exercise is limited by fatigue-induced reductions in maximum voluntary cycling power. Whether neuromuscular fatigue also limits exercise when the RI rate is slow and RI peak power at intolerance is lower than standard RI exercise, is unknown.MethodsIn twelve healthy participants, maximal voluntary cycling power was measured during a short (~6 s) isokinetic effort at 80 rpm (Piso) at baseline and, using an instantaneous switch from cadence-independent to isokinetic cycling, immediately at the limit of RI exercise with RI rates of 50, 25, and 10 W·min−1 (RI-50, RI-25, and RI-10). Breath-by-breath pulmonary gas exchange was measured throughout.ResultsBaseline Piso was not different among RI rates (analysis of variance; P > 0.05). Tolerable duration increased with decreasing RI rate (RI-50, 411 ± 58 s vs RI-25, 732 ± 93 s vs RI-10, 1531 ± 288 s; P < 0.05). At intolerance, V˙O2peak was not different among RI rates (analysis of variance; P > 0.05), but RI peak power decreased with RI rate (RI-50, 361 ± 48 W vs RI-25, 323 ± 39 W vs RI-10, 275 ± 38 W; P < 0.05). Piso at intolerance was 346 ± 43 W, 353 ± 45 W, and 392 ± 69 W for RI-50, RI-25, and RI-10, respectively (P < 0.05 for RI-10 vs RI-50 and RI-25). At intolerance, in RI-50 and RI-25, Piso was not different from RI peak power (P > 0.05), thus there was no “power reserve.” In RI-10, Piso was greater than RI peak power at intolerance (P < 0.001), that is, there was a “power reserve.”ConclusionsIn RI-50 and RI-25, the absence of a power reserve suggests the neuromuscular fatigue-induced reduction in Piso coincided with V˙O2max and limited the exercise. In RI-10, the power reserve suggests neuromuscular fatigue was insufficient to limit the exercise, and additional mechanisms contributed to intolerance at V˙O2max.

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“…By circumventing this adjustment period by using an instantaneous switch to isokinetic ergometry [20][21][22][23], it may be possible to measure an approximation of critical power in less than 30 s of "all-out" sprint type exercise. The switch to isokinetic cycling provides no electromagnetic braking resistance in returning to the appropriate flywheel velocity as no braking is applied below the target velocity.…”

Section: Introductionmentioning

confidence: 99%

Maximal Sustained Isokinetic Power at Exercise Intolerance is not Critical Power

et al. 2019

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The asymptote of the hyperbolic power-duration relationship, critical power (CP), demarcates sustainable from non-sustainable exercise. CP is a salient parameter within the theoretical framework determining exercise tolerance. However, measuring CP is time consuming – typically 4 constant-power exercise tests to intolerance, or a 3-min all-out sprint is required.To determine whether 30 s of maximal isokinetic cycling, immediately following the limit of tolerance, approximates CP.Fifteen participants (7 women, 8 men, 23±5 yr, 71±12 kg, V̇O2peak 4.39±1.04 L·min−1; 61±9 mL·kg·min−1) completed 4 constant supra-CP exercise tests to intolerance. Each test was followed immediately by a 30 s maximal isokinetic effort at 80 rpm. Mean isokinetic power was compared to the known CP.Mean±SD CP was 159±47 W (CI95 133, 185 W). Maximal isokinetic power immediately following intolerance was greater (p<0.05) than CP in all but one comparison (181±51 vs. 159±47 W; p>0.07). However, this closest estimation, following the longest duration constant-power test, resulted in 21 W of mean bias and wide limits of agreement (±84 W).Isokinetic power measured immediately following intolerance consistently overestimated critical power. Thus, an adjunct of 30 s maximal isokinetic cycling immediately following the limit of tolerance does not approximate critical power.

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Power-Velocity and Power-Efficiency Implications in the Limitation of Ramp Incremental Cycle Ergometry: Reply to Morales-Alamo et al.

Cited by 5 publications

References 5 publications

Power reserve following ramp-incremental cycling to exhaustion: implications for muscle fatigue and function

Power reserve following ramp-incremental cycling to exhaustion: implications for muscle fatigue and function

Power Reserve at Intolerance in Ramp-Incremental Exercise Is Dependent on Incrementation Rate

Maximal Sustained Isokinetic Power at Exercise Intolerance is not Critical Power

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