Influence of recovery intensity on oxygen demand and repeated sprint performance

AIM: This study aimed to determine effects of recovery intensity (passive, 20, 30 and 40%V̇ O2peak) on oxygen uptake kinetics, performance and blood lactate accumulation during repeated sprints. METHODS: 7 moderately-trained male participants (V̇O2peak: 48.1 ± 5.1 ml·kg-1·min-1) performed 4 x 30-s repeated Wingate tests on 4 separate occasions. RESULTS: Recovery of V̇ O2 between sprints was prolonged with recovery intensity (time required to reach 50% V̇O2peak: Passive: 50 ± 9; 20%: 81 ± 17; 30%: 130 ± 43; 40%: 188 ± 62 sec, P<0.001), while V̇O2-to-sprint work ratio was mainly increased by the higher intensities (Passive: 138 ± 17; 20%: 149 ± 14; 30%: 159 ± 15; 40%: 158 ± 17 ml·min-1·kJ-1, P=0.001). The decline in peak power tended to be greater in the higher intensity conditions during sprint 2 (Passive: 7.4 ± 5.4; 20%: 5.8 ± 7.9; 30%: 12.7 ± 7.4; 40%: 12.7 ± 5.5%, P=0.052), whereas average power was less decreased with recovery intensity during sprint 4 (Passive: 22.4 ± 8.9; 20%: 19.9 ± 6.1; 30%: 18.4 ± 7.3; 40%: 16.6 ± 6.2%, P=0.036). Blood lactate was not different with recovery intensity (P=0.251). CONCLUSION: The present study demonstrated that while the higher recovery intensities induce prolonged oxygen recovery and impaired peak power restoration during the initial sprints, those intensities provide a greater aerobic contribution to sprint performance, resulting in better power maintenance during the latter sprints

Lattice monopole action in pure SU(3) QCD

We obtain an almost perfect monopole action numerically after abelian projection in pure SU(3) lattice QCD. Performing block-spin transformations on the dual lattice, the action fixed depends only on a physical scale b. Monopole condensation occurs for large b region. The numerical results show that two-point monopole interactions are dominant for large b. We next perform the block-spin transformation analytically in a simplified case of two-point monopole interactions with a Wilson loop on the fine lattice. The perfect operator evaluating the static quark potential on the coarse b-lattice are derived. The monopole partition function can be transformed into that of the string model. The static potential and the string tension are estimated in the string model framework. The rotational invariance of the static potential is recovered, but the string tension is a little larger than the physical one.Comment: 21pages,4figures,to be published in JHE

Dust properties in the cold and hot gas phases of the ATLAS3D early-type galaxies as revealed by AKARI

The properties of the dust in the cold and hot gas phases of early-type galaxies (ETGs) are key to understand ETG evolution. We thus conducted a systematic study of the dust in a large sample of local ETGs, focusing on relations between the dust and the molecular, atomic, and X-ray gas of the galaxies, as well as their environment. We estimated the dust temperatures and masses of the 260 ETGs from the ATLAS3D survey, using fits to their spectral energy distributions primarily constructed from AKARI measurements. We also used literature measurements of the cold (CO and HI) and X-ray gas phases. Our ETGs show no correlation between their dust and stellar masses, suggesting inefficient dust production by stars and/or dust destruction in X-ray gas. The global dust-to-gas mass ratios of ETGs are generally lower than those of late-type galaxies, likely due to dust-poor HI envelopes in ETGs. They are also higher in Virgo Cluster ETGs than in group and field ETGs, but the same ratios measured in the central parts of the galaxies only are independent of galaxy environment. Slow-rotating ETGs have systematically lower dust masses than fast-rotating ETGs. The dust masses and X-ray luminosities are correlated in fast-rotating ETGs, whose star formation rates are also correlated with the X-ray luminosities. The correlation between dust and X-rays in fast-rotating ETGs appears to be caused by residual star formation, while slow-rotating ETGs are likely well evolved, and thus exhausting their dust. These results appear consistent with the postulated evolution of ETGs, whereby fast-rotating ETGs form by mergers of late-type galaxies and associated bulge growth, while slow-rotating ETGs form by (dry) mergers of fast-rotating ETGs. Central cold dense gas appears to be resilient against ram pressure stripping, suggesting that Virgo Cluster ETGs may not suffer strong related star formation suppression.Comment: 18 pages, 7 figures, accepted for publication in A&