Characterizing the profile of muscle deoxygenation during ramp incremental exercise in young men
Canadian Centre for Activity and Aging, The University of Western Ontario, London, ON, Canada. Arbeitsphysiologie
(Impact Factor: 2.19).
01/2012; 112(9):3349-60. DOI: 10.1007/s00421-012-2323-y
This study characterized the profile of near-infrared spectroscopy (NIRS)-derived muscle deoxygenation (Δ[HHb]) and the tissue oxygenation index (TOI) as a function of absolute (PO(ABS)) and normalized power output (%PO) or oxygen consumption (%VO(2)) during incremental cycling exercise. Eight men (24 ± 5 year) each performed two fatigue-limited ramp incremental cycling tests (20 W min(-1)), during which pulmonary VO(2), Δ[HHb] and TOI were measured continuously. Responses from the two tests were averaged and the TOI (%) and normalized Δ[HHb] (%Δ[HHb]) were plotted against %VO(2), %PO and PO(ABS). The overall responses were modelled using a sigmoid regression (y = f ( 0 ) + A/(1 + e(-(-c+dx)))) and piecewise 'double-linear' function of the predominant adjustment of %Δ[HHb] or TOI observed throughout the middle portion of exercise and the 'plateau' that followed. In ~85% of cases, the corrected Akaike Information Criterion (AIC(C)) was smaller (suggesting one model favoured) for the 'double-linear' compared with the sigmoid regression for both %Δ[HHb] and TOI. Furthermore, the f ( 0 ) and A estimates from the sigmoid regressions of %Δ[HHb] yielded unrealistically large projected peak (f ( 0 ) + A) values (%VO(2p) 114.3 ± 17.5; %PO 113.3 ± 9.5; PO(ABS) 113.5 ± 9.8), suggesting that the sigmoid model does not accurately describe the underlying physiological responses in all subjects and thus may not be appropriate for comparative purposes. Alternatively, the present study proposes that the profile of %Δ[HHb] and TOI during ramp incremental exercise may be more accurately described as consisting of three distinct phases in which there is little adjustment early in the ramp, the predominant increase in %Δ[HHb] (decrease in TOI) is approximately linear and an approximately linear 'plateau' follows.
Available from: Knut Skovereng
- "Several recent studies have investigated changes in HHb and/or tHb in relation to increasing external work rate (Bellotti, Calabria, Capelli, & Pogliaghi, 2013; Boone, Barstow, Celie, Prieur, & Bourgois, 2014; Boone, Koppo, Barstow, & Bouckaert, 2009; Ferreira, Koga, & Barstow, 2007; Ferreira, Lutjemeier, Townsend, & Barstow, 2006; Murias, Spencer, Keir, & Paterson, 2013; Spencer, Murias, & Paterson, 2012). Indeed with regard to HHB, these studies show that individual muscles show a non-linear response to a change in cycling exercise intensity, with a tendency to level off as intensity increases above $82% of peak external work rate (Bellotti et al., 2013; Boone et al., 2009; Ferreira et al., 2007; Murias et al., 2013; Nagasawa, 2008; Spencer et al., 2012). Blood volume has been reported to plateau at $80% of peak external work rate during incremental cycling exercise (Boone et al., 2014) and also to be similar at lactate threshold compared to maximal exercise (Ferreira et al., 2006). "
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ABSTRACT: The purpose of the present study was to examine the effects of external work rate on joint specific power and the relationship between knee extension power and vastus lateralis muscle oxygen consumption (mVO2). We measured kinematics and pedal forces and used inverse dynamics to calculate joint power for the hip, knee and ankle joints during an incremental cycling protocol performed by 21 recreational cyclists. Vastus lateralis mVO2 was estimated using near-infrared spectroscopy with an arterial occlusion. The main finding was a non-linear relationship between vastus lateralis mVO2 and external work rate that was characterised by an increase followed by a tendency for a levelling off (R2=0.99 and 0.94 for the quadratic and linear models respectively, p<0.05). When comparing 100W and 225W, there was a ∼43W increase in knee extension but still a ∼9% decrease in relative contribution of knee extension to external work rate resulting from a ∼47W increase in hip extension. When vastus lateralis mVO2 was related to knee extension power, the relationship was still non-linear (R2=0.99 and 0.97 for the quadratic and linear models respectively, p<0.05). These results demonstrate a non-linear response in mVO2 relative to a change in external work rate. Relating vastus lateralis mVO2 to knee extension power showed a better fit to a linear equation compared to external work rate, but it is not a straight line.
- "The iEMG and MPF values, and deoxy[Hb+Mb] and total[Hb+Mb] values were plotted as functions of work rate. The pattern of iEMG, MPF, deoxy[Hb+Mb], and total[Hb+Mb] (as functions of work rate and %V ˙ O 2peak ) was analyzed by means of a double linear model (Osawa et al. 2011; Spencer et al. 2012; Boone et al. 2015) (SigmaPlot 11.0, Systat Software, Calif., USA), yielding for the first linear function (low-to-moderate work rates): "
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ABSTRACT: We investigated whether muscle and ventilatory responses to incremental ramp exercise would be influenced by aerobic fitness status by means of a cross-sectional study with a large subject population. Sixty-four male students (age: 21.2 ± 3.2 years) with a heterogeneous peak oxygen uptake (51.9 ± 6.3 mL·min(-1)·kg(-1), range 39.7-66.2 mL·min(-1)·kg(-1)) performed an incremental ramp cycle test (20-35 W·min(-1)) to exhaustion. Breath-by-breath gas exchange was recorded, and muscle activation and oxygenation were measured with surface electromyography and near-infrared spectroscopy, respectively. The integrated electromyography (iEMG), mean power frequency (MPF), deoxygenated [hemoglobin and myoglobin] (deoxy[Hb+Mb]), and total[Hb+Mb] responses were set out as functions of work rate and fitted with a double linear function. The respiratory compensation point (RCP) was compared and correlated with the breakpoints (BPs) (as percentage of peak oxygen uptake) in muscle activation and oxygenation. The BP in total[Hb+Mb] (83.2% ± 3.0% peak oxygen uptake) preceded (P < 0.001) the BP in iEMG (86.7% ± 4.0% peak oxygen uptake) and MPF (86.3% ± 4.1% peak oxygen uptake), which in turn preceded (P < 0.01) the BP in deoxy[Hb+Mb] (88.2% ± 4.5% peak oxygen uptake) and RCP (87.4% ± 4.5% peak oxygen uptake). Furthermore, the peak oxygen uptake was significantly (P < 0.001) positively correlated to the BPs and RCP, indicating that the BPs in total[Hb+Mb] (r = 0.66; P < 0.001), deoxy[Hb+Mb] (r = 0.76; P < 0.001), iEMG (r = 0.61; P < 0.001), MPF (r = 0.63; P < 0.001), and RCP (r = 0.75; P < 0.001) occurred at a higher percentage of peak oxygen uptake in subjects with a higher peak oxygen uptake. In this study a close relationship between muscle oxygenation, activation, and pulmonary oxygen uptake was found, occurring in a cascade of events. In subjects with a higher aerobic fitness level this cascade occurred at a higher relative intensity.
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The current investigation assessed tissue oxygenation and local blood volume in both vastus lateralis muscles during 3000-m race simulations in elite speed skaters on ice and the effects of leg compression on physiological, perceptual, and performance measures.
Ten (6 female) elite ice speed skaters completed 2 on-ice trials with and without leg compression. Tissue oxygenation and local blood volume in both vastus lateralis muscles were assessed with near-infrared spectroscopy. Continuous measures of oxygen uptake, ventilation, heart rate, and velocity were conducted throughout the race simulations, as well as blood lactate concentration and ratings of perceived exertion before and after the trials. In addition, lap times were assessed.
The investigation of tissue oxygenation in both vastus lateralis muscles revealed an asymmetry (P < .00; effect size = 1.81) throughout the 3000-m race simulation. The application of leg compression did not affect oxygenation asymmetry (smallest P = .99; largest effect size = 0.31) or local blood volume (P = .33; 0.95). Lap times (P = .88; 0.43), velocity (P = .24; 0.84), oxygen uptake (P = .79; 0.10), ventilation (P = .11; 0.59), heart rate (P = .21; 0.89), blood lactate concentration (P = .82; 0.59), and ratings of perceived exertion (P = .19; 1.01) were also unaffected by the different types of clothing.
Elite ice speed skaters show an asymmetry in tissue oxygenation of both vastus lateralis muscles during 3000-m events remaining during the long gliding phases along the straight sections of the track. Based on the data, the authors conclude that there are no performance-enhancing benefits from wearing leg compression under a normal racing suit.
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