scholarly journals Determinants of curvature constant (W’) of the power duration relationship under normoxia and hypoxia: the effect of pre-exercise alkalosis

2017 ◽  
Vol 117 (5) ◽  
pp. 901-912 ◽  
Author(s):  
Sanjoy K. Deb ◽  
Lewis A. Gough ◽  
S. Andy Sparks ◽  
Lars R. McNaughton
Keyword(s):  
Duration Relationship

Effects of Normobaric Hypoxia on Matched-severe Exercise and Power-duration Relationship

2021 ◽  
Author(s):  
Ana Catarina Sousa ◽  
Gregoire P. Millet ◽  
João Viana ◽  
Jaime Milheiro ◽  
Vítor Reis
Keyword(s):  
Relative Intensity ◽  
Slow Component ◽  
Exponential Model ◽  
Normobaric Hypoxia ◽  
Time To Exhaustion ◽  
V̇o2 Kinetics ◽  
Severe Intensity ◽  
Lower Oxygen ◽  
Severe Exercise ◽  
Duration Relationship

AbstractWe investigated the effects of hypoxia on matched-severe intensity exercise and on the parameters of the power-duration relationship. Fifteen trained subjects performed in both normoxia and normobaric hypoxia (FiO2=0.13, ~3000 m) a maximal incremental test, a 3 min all-out test (3AOT) and a transition from rest to an exercise performed to exhaustion (Tlim) at the same relative intensity (80%∆). Respiratory and pulmonary gas-exchange variables were continuously measured (K5, Cosmed, Italy). Tlim test’s V̇O2 kinetics was calculated using a two-component exponential model. V̇O2max (44.1±5.1 vs. 58.7±6.4 ml.kg-1.min-1, p<0.001) was decreased in hypoxia. In Tlim, time-to-exhaustion sustained was similar (454±130 vs. 484±169 s) despite that V̇O2 kinetics was slower (τ1: 31.1±5.8 vs. 21.6±4.7 s, p<0.001) and the amplitude of the V̇O2 slow component lower (12.4±5.4 vs. 20.2±5.7 ml.kg-1.min-1, p<0.05) in hypoxia. CP was reduced (225±35 vs. 270±49 W, p<0.001) but W’ was unchanged (11.3±2.9 vs. 11.4±2.7 kJ) in hypoxia. The changes in CP/V̇O2max were positively correlated with changes in W’ (r = 0.58, p<0.05). The lower oxygen availability had an impact on aerobic related physiological parameters, but exercise tolerance is similar between hypoxia and normoxia when the relative intensity is matched despite a slower V̇O2 kinetics in hypoxia.

Luminance-Duration Relationship in the Human ERG

1972 ◽  
pp. 277-285
Author(s):  
Yutaka Tsuchida ◽  
Kazuo Kawasaki ◽  
Jerry H. Jacobson
Keyword(s):  
Duration Relationship

Estimation of critical torque using intermittent isometric maximal voluntary contractions of the quadriceps in humans

2009 ◽  
Vol 106 (3) ◽  
pp. 975-983 ◽  
Author(s):  
Mark Burnley
Keyword(s):  
Laboratory Tests ◽  
Mean Squared Error ◽  
Voluntary Activation ◽  
Peripheral Fatigue ◽  
Contraction Time ◽  
Twitch Interpolation ◽  
Squared Error ◽  
The Mean ◽  
Duration Relationship ◽  
Voluntary Contractions

To determine whether the asymptote of the torque-duration relationship (critical torque) could be estimated from the torque measured at the end of a series of maximal voluntary contractions (MVCs) of the quadriceps, eight healthy men performed eight laboratory tests. Following familiarization, subjects performed two tests in which they were required to perform 60 isometric MVCs over a period of 5 min (3 s contraction, 2 s rest), and five tests involving intermittent isometric contractions at ∼35–60% MVC, each performed to task failure. Critical torque was determined using linear regression of the torque impulse and contraction time during the submaximal tests, and the end-test torque during the MVCs was calculated from the mean of the last six contractions of the test. During the MVCs voluntary torque declined from 263.9 ± 44.6 to 77.8 ± 17.8 N·m. The end-test torque was not different from the critical torque (77.9 ± 15.9 N·m; 95% paired-sample confidence interval, −6.5 to 6.2 N·m). The root mean squared error of the estimation of critical torque from the end-test torque was 7.1 N·m. Twitch interpolation showed that voluntary activation declined from 90.9 ± 6.5% to 66.9 ± 13.1% ( P < 0.001), and the potentiated doublet response declined from 97.7 ± 23.0 to 46.9 ± 6.7 N·m ( P < 0.001) during the MVCs, indicating the development of both central and peripheral fatigue. These data indicate that fatigue during 5 min of intermittent isometric MVCs of the quadriceps leads to an end-test torque that closely approximates the critical torque.

Contract Development

2011 ◽  
pp. 168-183
Author(s):  
P. Gottschalk
Keyword(s):  
Risk Sharing ◽  
Contract Negotiations ◽  
Contract Duration ◽  
Key Issues ◽  
Contract Structure ◽  
Duration Relationship ◽  
Outsourcing Contracts ◽  
Technology Upgrading ◽  
Is Outsourcing

According to Graham (2003), one of the games lawyers play in negotiation meetings relating to outsourcing is to bet how long it will be until one party describes the outsourcing as a “partnership.” Nothing could be farther from the truth: the parties’ interests overlap, but they are not congruent, and neither party will put its existence on the line for the other. A relevant approach in contract negotiations is to see the outsourcing as the creation of a long-term, flexible relationship, but one that exists within a framework of rules that support its success while addressing failures practically. The contract, therefore, has a sophisticated role not only as the passive record of the parties’ agreement, but also as the guidebook for the evolving transaction. This chapter considers the structure of the contractual documents and the key issues that need to be reflected in them. Elizur and Wensley (1998) apply game theory in their study of IS outsourcing contracts. They find six typical issues arising in an outsourcing situation: the transfer of IS assets, risk sharing, technology upgrading, contract duration, relationship management, and fee arrangements. In addition, we have added the important topics of due diligence and dispute resolution. We will consider each of these issues separately after our discussion of contract structure.

scholarly journals Determination of the power-duration relationship in upper-limb exercises

2010 ◽  
Author(s):  
Domingos Belasco Junior ◽  
Fernando R. Oliveira ◽  
José A. N. Serafini
Keyword(s):  
Upper Limb ◽  
Duration Relationship

scholarly journals Sex differences in fatigability and recovery relative to the intensity–duration relationship

2019 ◽  
Vol 597 (23) ◽  
pp. 5577-5595 ◽  
Author(s):  
Paul Ansdell ◽  
Callum G. Brownstein ◽  
Jakob Škarabot ◽  
Kirsty M. Hicks ◽  
Glyn Howatson ◽  
...  
Keyword(s):  
Sex Differences ◽  
Duration Relationship

scholarly journals Muscle metabolic responses during high-intensity intermittent exercise measured by 31P-MRS: relationship to the critical power concept

2013 ◽  
Vol 305 (9) ◽  
pp. R1085-R1092 ◽  
Author(s):  
Weerapong Chidnok ◽  
Fred J. DiMenna ◽  
Jonathan Fulford ◽  
Stephen J. Bailey ◽  
Philip F. Skiba ◽  
...  
Keyword(s):  
High Intensity ◽  
Critical Power ◽  
Intermittent Exercise ◽  
High Intensity Exercise ◽  
Interval Duration ◽  
Constant Power ◽  
Recovery Interval ◽  
Duration Relationship ◽  
Recovery Protocols ◽  
Work Done

We investigated the responses of intramuscular phosphate-linked metabolites and pH (as assessed by 31P-MRS) during intermittent high-intensity exercise protocols performed with different recovery-interval durations. Following estimation of the parameters of the power-duration relationship, i.e., the critical power ( CP) and curvature constant ( W′), for severe-intensity constant-power exercise, nine male subjects completed three intermittent exercise protocols to exhaustion where periods of high-intensity constant-power exercise (60 s) were separated by different durations of passive recovery (18 s, 30 s and 48 s). The tolerable duration of exercise was 304 ± 68 s, 516 ± 142 s, and 847 ± 240 s for the 18-s, 30-s, and 48-s recovery protocols, respectively ( P < 0.05). The work done > CP ( W> CP) was significantly greater for all intermittent protocols compared with the subjects' W′, and this difference became progressively greater as recovery-interval duration was increased. The restoration of intramuscular phosphocreatine concentration during recovery was greatest, intermediate, and least for 48 s, 30 s, and 18 s of recovery, respectively ( P < 0.05). The W> CP in excess of W′ increased with greater durations of recovery, and this was correlated with the mean magnitude of muscle phosphocreatine reconstitution between work intervals ( r = 0.61; P < 0.01). The results of this study show that during intermittent high-intensity exercise, recovery intervals allow intramuscular homeostasis to be restored, with the degree of restoration being related to the duration of the recovery interval. Consequently, and consistent with the intermittent CP model, the ability to perform W> CP during intermittent high-intensity exercise and, therefore, exercise tolerance, increases when recovery-interval duration is extended.

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