Heterogeneity of muscle deoxygenation kinetics during two bouts of repeated heavy exercises

Univ Lille Nord de France, 59000, Lille, France.
Arbeitsphysiologie (Impact Factor: 2.19). 04/2010; 109(6):1047-57. DOI: 10.1007/s00421-010-1446-2
Source: PubMed


This study examines the effect of prior heavy exercise on the spatial distribution of muscle deoxygenation kinetics at the onset of heavy-intensity cycling exercise. Young untrained male adults (n = 16) performed two consecutive bouts of 6 min of high intensity cycle exercise separated by 6 min at 35 W. Muscle deoxygenation (HHb) was monitored continuously by near-infrared spectroscopy at eight sites in the quadriceps. Prior heavy exercise reduced the delay before the increase in HHb (9 +/- 2 vs. 5 +/- 2 s; P < 0.001). The standard deviation of TD HHb of the eight sites was decreased by the performance of prior exercise (1.1 +/- 0.5 vs. 0.8 +/- 0.4 s; P < 0.05). The transient decrease in HHb during the first 10 s of exercise was less during the second bout than during the first bout (0.6 +/- 0.6 vs. 0.3 +/- 0.3 A.U.; P < 0.01). The standard deviation of this decrease was also reduced by prior exercise (0.5 +/- 0.3 vs. 0.3 +/- 0.2 A.U.; P < 0.01). Lastly, prior exercise decreased significantly the standard deviation of the HHb rise during the time period corresponding to the pulmonary VO(2) slow component. These results indicate that prior heavy exercise reduced the spatial heterogeneity of muscle deoxygenation kinetics at the early onset of heavy exercise and during the development of the pulmonary VO(2) slow component. It indicates that the distribution of the VO(2)/O(2) delivery ratio within muscle was improved by the performance of a prior exercise.

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    • "With the limitation of NIRS to monitor the actual muscle O2 demands, present results suggest that HIE with two 90°-COD and a ~25% lower average running speed, elicits, in comparison with straight-line runs, an equivalent modification of the local O2 uptake/delivery ratio, which is in agreement with the systemic VO2 measures. The extrapolation of this findings to the overall lower musculature should however be viewed with caution given the large heterogeneity of muscle (de)oxygenation within the same muscle [46]. "
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    ABSTRACT: The ability to sustain brief high-intensity intermittent efforts (HIE) is meant to be a major attribute for performance in team sports. Adding changes of direction to HIE is believed to increase the specificity of training drills with respect to game demands. The aim of this study was to investigate the influence of 90[degree sign]-changes of direction (COD) during HIE on metabolic and neuromuscular responses. Eleven male, team sport players (30.5 +/- 3.6 y) performed randomly HIE without (straight-line, 2x[10x 22 m]) or with (2x[10x ~16.5 m]) two 90[degree sign]-COD. To account for the time lost while changing direction, the distance for COD runs during HIE was individually adjusted using the ratio between straight-line and COD sprints. Players also performed 2 countermovement (CMJ) and 2 drop (DJ) jumps, during and post HIE. Pulmonary oxygen uptake (VO2), quadriceps and hamstring oxygenation, blood lactate concentration (Delta[La]b), electromyography amplitude (RMS) of eight lower limb muscles and rating of perceived exertion (RPE) were measured for each condition. During HIE, CODs had no substantial effects on changes in VO2, oxygenation, CMJ and DJ performance and RPE (all differences in the changes rated as unclear). Conversely, compared with straight-line runs, COD-runs were associated with a possibly higher Delta[La]b (+9.7 +/- 10.4%, with chances for greater/similar/lower values of 57/42/0%)and either a lower (i.e., -11.9 +/- 14.6%, 2/13/85 for semitendinosus and -8.5 +/- 9.3%, 1/21/78 for lateral gastrocnemius) or equivalent decrease in electromyography amplitude. Adding two 90[degree sign]-CODs on adjusted distance during two sets of HIE is likely to elicit equivalent decreases in CMJ and DJ height, and similar cardiorespiratory and perceptual responses, despite a lower average running speed. A fatigue-induced modification in lower limb control observed with CODs may have elicited a selective reduction of electromyography activity in hamstring muscles and may induce, in turn, a potential mechanical loss of knee stability. Therefore, changing direction during HIE, with adjusted COD running distances, might be an effective training practice 1) to manipulate some components of the acute physiological load of HIE, 2) to promote long-term COD-specific neuromuscular adaptations aimed at improving performance and knee joint stability.
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    • "The NIRS-derived deoxygenation signal can be measured continuously during exercise and provides information on the dynamic adjustment of local muscle O 2 extraction in the region of NIRS interrogation (Grassi et al. 2003). It has already been shown that muscle deoxygenation is heterogeneous in a single muscle during a cycle exercise (Koga et al. 2007, 2011; Kime et al. 2005; Prieur et al. 2010). This nonuniform deoxygenation across the muscle reflects heterogeneous O 2 delivery and (or) O 2 demand across a muscle. "
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    ABSTRACT: This study examined the effect of pedal cadence on the heterogeneity of muscle deoxygenation during exercise of moderate intensity. Twelve healthy subjects performed 6 min of cycling at 40 and 100 r·min(-1) at 80% of the workload corresponding to the gas exchange threshold. Gas exchanges were measured breath by breath during each exercise. Muscle deoxygenation (HHb, i.e., O2 extraction) was monitored continuously by near-infrared spectroscopy at eight sites on the vastus lateralis. The heterogeneity of HHb was assessed using the relative dispersion of the signal measured at the eight sites (i.e., 100 × standard deviation / mean). HHb was not altered by the pedal cadence, whereas pulmonary V̇O2 was higher at 100 r·min(-1) than at 40 r·min(-1) (p < 0.001). The relative dispersion of HHb was significantly higher at 100 r·min(-1) than at 40 r·min(-1) (p < 0.001). These results indicate that pedal cadence has no effect on O2 extraction but that an elevated cadence would increase muscle V̇O2, suggesting an increase in muscle blood flow. Elevated cadence also induced greater heterogeneity of the muscle's V̇O2/Q̇O2 delivery ratio, suggesting a change in the adequacy between O2 demand and O2 delivery in some regions of active muscle.
    No preview · Article · Dec 2013 · Applied Physiology Nutrition and Metabolism
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    • "For instance, while the cuff pressure was >300 mmHg and therefore expected to entirely interrupt O 2 delivery, we did not have objective data to ascertain this. Because of the important heterogeneity of muscle oxygenation levels (Prieur et al., 2010), small differences in NIRS probe replacement could have also contributed to day-by-day differences in NIRS measures. Nevertheless, pen marks were used for accurate probe repositioning, so this latter factor is unlikely to completely explain the variability observed. "
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    ABSTRACT: The purpose of this study was to assess the reliability of postexercise near-infrared spectroscopy (NIRS)-derived measurements and their sensitivity to different exercise intensities in the field. Seventeen athletes (24·1 ± 5·6 year) repeated, on three occasions, two 2-min submaximal shuttle-runs at 40% and 60% of V(IFT) (final speed of the 30-15 intermittent fitness test) and a 50-m shuttle-run sprint (Sprint), with (OCC) or without (CON) repeated transient arterial occlusions of the medial gastrocnemius during the postexercise period. NIRS variables (i.e. oxyhaemoglobin [HbO(2)], deoxyhaemoglobin [HHb] and their difference [Hb(diff)]) were measured continuously for 3 min after each exercise. Half-recovery (½Rec) and mean response (MRT; monoexponential curve fitting) times of muscle reoxygenation and muscle oxygen uptake (mVO(2)) recovery were calculated. Reliability was assessed using the typical error of measurement, expressed as a coefficient of variation (CV). Postexercise recovery of muscle reoxygenation revealed CVs ranging from 16·8% to 37·3%; CV for mVO(2) recovery ranged from 6·2% to 20·9%, with no substantial differences shown between NIRS variables and exercise intensities. While running, intensity did not affect MRT or ½Rec for muscle reoxygenation, and differences were found for mVO(2) recovery (e.g. [Hb(diff)]-mVO(2) MRT = 28·7 ± 5·2, 34·2 ± 5·1 and 37·3 ± 6·2 s for 40%, 60% and Sprint, respectively, P<0·01). To conclude, the kinetics of postexercise NIRS measurements showed CV values ranging from 6% to 37%, with no substantial differences between exercise intensities or NIRS-derived variables. However, exercise intensity did influence mVO(2) recovery kinetics, but not that of muscle reoxygenation in an occlusion-free condition.
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