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Daisuke Kume, Akira Iguchi, and Hiroshi Endoh

, 26 , 38 , 39 ). These inflection points were approximately representative of accelerated muscle deoxygenation and were highly correlated with the onset of blood lactate accumulation, the respiratory gas-derived systemic threshold, and exercise performance ( 15 , 38 , 39 ). Therefore, muscle

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Tatiane Piucco, Rogério Soares, Fernando Diefenthaeler, Guillaume Y. Millet, and Juan M. Murias

Transmitter; Polar Electro Inc, Kempele, Finland). GET was identified by 2 blinded experts. If a discrepancy of more than 200 mL·min −1 was detected, a third expert was involved and the average of the 2 closest values was used. Local muscle deoxygenation profiles of the quadriceps vastus lateralis (VL

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Erwan Leclair, Delphine Thevenet, Sophie C. Reguem, Benoit Borel, Georges Baquet, Serge Berthoin, and Patrick Mucci

This study was designed to test the reproducibility of muscle oxygenation by NIRS in children during exercise. Twelve healthy non-obese and non-trained children performed one maximal graded test, and four 6-min constant load cycle exercises. Deoxy-hemoglobin (Hb/Mb-H+) data were averaged every 1, 5, 10, 20 and 30s. Hb/Mb-H+ data averaged every 5, 10, 20 and 30s showed good reproducibility. When averaged every second, Hb/Mb-H+ values were reproducible after the first minute of exercise. Based on 1s averaged signal modeling, time period and t values for Hb/Mb-H+ were not reproducible but mean response time values showed an acceptable reproducibility.

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Gianluca Vernillo, Alfredo Brighenti, Eloisa Limonta, Pietro Trabucchi, Davide Malatesta, Grégoire P. Millet, and Federico Schena

Purpose:

To quantify changes in skeletal-muscle oxygenation and pulmonary O2 uptake (V̇O2) after an extreme ultratrail running bout.

Methods:

Before (PRE) and after (POST) the race (330-km, 24000 D±), profiles of vastus lateralis muscle oxygenation (ie, oxyhemoglobin [O2Hb], deoxyhemoglobin [HHb], and tissue oxygenation index [TOI]) and V̇O2 were determined in 14 athletes (EXP) and 12 control adults (CON) during two 4-min constant-load cycling bouts at power outputs of 1 (p1) and 1.5 (p1.5) W/kg performed in randomized order.

Results:

At POST, normalized [HHb] values increased (p1, +38.0%; p1.5, +27.9%; P < .05), while normalized [O2Hb] (p1, –20.4%; p1.5, –14.4%; P < .05) and TOI (p1, –17.0%; p1.5, –17.7%; P < .05) decreased in EXP. V̇O2 values were similar (P > 0.05). An “overshoot“ in normalized [HHb]:V̇O2 was observed, although the increase was significant only during p1.5 (+58.7%, P = .003). No difference in the aforementioned variables was noted in CON (P > .05).

Conclusions:

The concentric and, particularly, the eccentric loads characterizing this extreme ultratrail-running bout may have led to variations in muscle structure and function, increasing the local muscle deoxygenation profile and the imbalance between O2 delivery to working muscles and muscle O2 consumption. This highlights the importance of incorporating graded training, particularly downhill bouts, to reduce the negative influence of concentric and severe eccentric loads to the microcirculatory function and to enhance the ability of runners to sustain such loading.

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Manuel Matzka, Christoph Zinner, Philipp Kunz, Hans-Christer Holmberg, and Billy Sperlich

. PubMed ID: 19396614 10.1007/s00421-009-1061-2 19396614 15. Paquette M , Bieuzen F , Billaut F . Sustained muscle deoxygenation vs sustained high VO 2 during high-intensity interval training in sprint canoe-kayak [published online ahead of print July 31, 2019]. Front Sports Act Living. 2019

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Kurt J. Smith and François Billaut

Purpose:

To understand the role of O2 utilization in the sex differences of fatigue during intermittent activity, we compared the cerebral (prefrontal lobe) and muscle (vastus lateralis) oxygenation of men and women during repeated-sprint exercise (RSE).

Methods:

Ten men and 10 women matched for initial-sprint mechanical work performed ten, 10 s cycle sprints (with 30 s of rest) under normoxic (NM: 21% FIO2) and acute hypoxic (HY: 13% FIO2) conditions in a randomized single-blind and crossover design. Mechanical work was calculated and arterial O2 saturation (SpO2) was estimated via pulse oximetry during every sprint. Cerebral and muscle oxy- (O2Hb) and deoxy-hemoglobin (HHb) were monitored continuously by near-infrared spectroscopy.

Results:

Compared with NM, work decrement was accentuated (P = 0.01) in HY for both men (–16.4 ± 10.3%) and women (–16.8 ± 9.0%). This was associated with lower SpO2 and lower cerebral Δ[O2Hb] in both sexes (–13.6 ± 7.5%, P = .008, and –134.5 ± 73.8%, P = .003, respectively). These HY-induced changes were nearly identical in these men and women matched for initial-sprint work. Muscle Δ[HHb] increased 9-fold (P = .009) and 5-fold (P = .02) in men and women, respectively, and plateaued. This muscle deoxygenation was not exacerbated in HY.

Conclusions:

Results indicate that men and women matched for initial-sprint work experience similar levels of fatigue and systemic, cerebral, and peripheral adjustments during RSE performed in NM and HY. These data suggest that cerebral deoxygenation imposes a limitation to repeated-sprint performance.

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Thiago Oliveira Borges, Ben Dascombe, Nicola Bullock, and Aaron J. Coutts

This study aimed to profile the physiological characteristics of junior sprint kayak athletes (n = 21, VO2max 4.1 ± 0.7 L/min, training experience 2.7 ± 1.2 y) and to establish the relationship between physiological variables (VO2max, VO2 kinetics, muscle-oxygen kinetics, paddling efficiency) and sprint kayak performance. VO2max, power at VO2max, power:weight ratio, paddling efficiency, VO2 at lactate threshold, and whole-body and muscle oxygen kinetics were determined on a kayak ergometer in the laboratory. Separately, on-water time trials (TT) were completed over 200 m and 1000 m. Large to nearly perfect (−.5 to −.9) inverse relationships were found between the physiological variables and on-water TT performance across both distances. Paddling efficiency and lactate threshold shared moderate to very large correlations (−.4 to −.7) with 200- and 1000-m performance. In addition, trivial to large correlations (−.11 to −.5) were observed between muscle-oxygenation parameters, muscle and whole-body oxygen kinetics, and performance. Multiple regression showed that 88% of the unadjusted variance for the 200-m TT performance was explained by VO2max, peripheral muscle deoxygenation, and maximal aerobic power (P < .001), whereas 85% of the unadjusted variance in 1000-m TT performance was explained by VO2max and deoxyhemoglobin (P < .001). The current findings show that well-trained junior sprint kayak athletes possess a high level of relative aerobic fitness and highlight the importance of the peripheral muscle metabolism for sprint kayak performance, particularly in 200-m races, where finalists and nonfinalists are separated by very small margins. Such data highlight the relative aerobic-fitness variables that can be used as benchmarks for talent-identification programs or monitoring longitudinal athlete development. However, such approaches need further investigation.

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.1123/pes.22.2.176 Original Research Reproducibility of Measurement of Muscle Deoxygenation in Children During Exercise Erwan Leclair * Delphine Thevenet * Sophie C. Reguem * Benoit Borel * Georges Baquet * Serge Berthoin * Patrick Mucci * 5 2010 22 2 183 194 10.1123/pes.22.2.183 Research The

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.2017-0217 pes.2017-0217 Onset of Accelerated Muscle Deoxygenation During the 20-m Shuttle Run Test in Boys Daisuke Kume * Akira Iguchi * Hiroshi Endoh * 1 11 2018 30 4 474 479 10.1123/pes.2017-0210 pes.2017-0210 The Effects of a 12-Week Combined Exercise Training Program on Arterial Stiffness

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Tiago Turnes, Rafael Penteado dos Santos, Rafael Alves de Aguiar, Thiago Loch, Leonardo Trevisol Possamai, and Fabrizio Caputo

]BP of the vastus lateralis muscle. The disagreement between the previous studies and this study may be due to the different exercise modalities used. Indeed, the breaking point of muscle deoxygenation in the vastus lateralis and gastrocnemius during cycling 10 and running, 7 respectively, has been