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1.
This study examined the test-retest reliability of near-infrared spectroscopy (NIRS), laser Doppler flowmetry (LDF) and Doppler ultrasound to assess exercise-induced haemodynamics. Nine men completed two identical trials consisting of 25-min submaximal cycling at first ventilatory threshold followed by repeated 30-s bouts of high-intensity (90% of peak power) cycling in 32.8 ± 0.4°C and 32 ± 5% relative humidity (RH). NIRS (tissue oxygenation index [TOI] and total haemoglobin [tHb]) and LDF (perfusion units [PU]) signals were monitored continuously during exercise, and leg blood flow was assessed by Doppler ultrasound at baseline and after exercise. Cutaneous vascular conductance (CVC; PU/mean arterial pressure (MAP)) was expressed as the percentage change from baseline (%CVCBL). Coefficients of variation (CVs) as indicators of absolute reliability were 18.7–28.4%, 20.2–33.1%, 42.5–59.8%, 7.8–12.4% and 22.2–30.3% for PU, CVC, %CVCBL, TOI and tHb, respectively. CVs for these variables improved as exercise continued beyond 10 min. CVs for baseline and post-exercise leg blood flow were 17.8% and 10.5%, respectively. CVs for PU, tHb (r2 = 0.062) and TOI (r2 = 0.002) were not correlated (P > 0.05). Most variables demonstrated CVs lower than the expected changes (35%) induced by training or heat stress; however, minimum of 10 min exercise is recommended for more reliable measurements.  相似文献   

2.
Skin and core tissue cooling modulates skeletal muscle oxygenation at rest. Whether tissue cooling also influences the skeletal muscle deoxygenation response during exercise is unclear. We evaluated the effects of skin and core tissue cooling on skeletal muscle blood volume and deoxygenation during sustained walking and running. Eleven male participants walked or ran six times on a treadmill for 60 min in ambient temperatures of 22°C (Neutral), 0°C for skin cooling (Cold 1), and at 0°C following a core and skin cooling protocol (Cold 2). Difference between oxy/deoxygenated haemoglobin ([diffHb]: deoxygenation index) and total haemoglobin content ([tHb]: total blood volume) in the vastus lateralis (VL) muscle was measured continuously. During walking, lower [tHb] was observed at 1 min in Cold 1 and Cold 2 vs. Neutral (P?0.05). Lower [diffHb] was seen at 1 and 10 min in Cold 2 vs. Neutral by 13.5 ± 1.2 µM and 15.3 ± 1.4 µM and Cold 1 by 10.4 ± 3.1 µM and 11.1 ± 4.1 µM, respectively (P?0.05). During running, [tHb] was lower in Cold 2 vs. Neutral at 10 min only (P = 0.004). [diffHb] was lower at 1 min in Cold 2 by 11.3 ± 3.1 µM compared to Neutral and by 13.5 ± 2.8 µM compared to Cold 1 (P?0.001). Core tissue cooling, prior to exercise, induced greater deoxygenation of the VL muscle during the early stages of exercise, irrespective of changes in blood volume. Skin cooling alone, however, did not influence deoxygenation of the VL during exercise.  相似文献   

3.
ABSTRACT

This study assessed the intra-individual reliability of oxygen saturation in intercostal muscles (SmO2-m.intercostales) during an incremental maximal treadmill exercise by using portable NIRS devices in a test-retest study. Fifteen marathon runners (age, 24.9 ± 2.0 years; body mass index, 21.6 ± 2.3 kg·m?2; V?O2-peak, 63.7 ± 5.9 mL·kg?1·min?1) were tested on two separate days, with a 7-day interval between the two measurements. Oxygen consumption (V?O2) was assessed using the breath-by-breath method during the V?O2-test, while SmO2 was determined using a portable commercial device, based in the near-infrared spectroscopy (NIRS) principle. The minute ventilation (VE), respiratory rate (RR), and tidal volume (Vt) were also monitored during the cardiopulmonary exercise test. For the SmO2-m.intercostales, the intraclass correlation coefficient (ICC) at rest, first (VT1) and second ventilatory (VT2) thresholds, and maximal stages were 0.90, 0.84, 0.92, and 0.93, respectively; the confidence intervals ranged from ?10.8% – +9.5% to ?15.3% – +12.5%. The reliability was good at low intensity (rest and VT1) and excellent at high intensity (VT2 and max). The Spearman correlation test revealed (p ≤ 0.001) an inverse association of SmO2-m.intercostales with V?O2 (ρ = ?0.64), VE (ρ = ?0.73), RR (ρ = ?0.70), and Vt (ρ = ?0.63). The relationship with the ventilatory variables showed that increased breathing effort during exercise could be registered adequately using a NIRS portable device.  相似文献   

4.
Abstract

The aim of this study was to examine the time-course of and the relationships between muscle oxygenation, blood volume and myoelectrical manifestations during isometric exercise in children. Twelve healthy children aged 12.5 ± 1.2 years (mean ± s) performed an isometric knee extension at 50% of their maximal voluntary contraction (MVC) until exhaustion to assess endurance time (limit time, T lim). Changes in muscle oxygenation and blood volume were assessed by near infrared spectroscopy (NIRS). The root mean square (RMS) amplitude and the mean power frequency (MPF) from electromyogram (EMG) signals were obtained, as NIRS parameters, from the vastus lateralis. Mean T lim was 117 ± 34 s. The muscle oxygenation and blood volume curves decreased immediately at the beginning of exercise. Maximal deoxygenation occurred at 50% T lim, and fell by 76.9% from the resting value. Similarly, minimal blood volume was observed at 50% T lim; it reached a plateau that lasted until the end of exercise. The kinetics of the MPF and RMS curves were inversely related to time. At the last set of exercises (after 75% T lim), a steeper RMS curve and an abrupt decrease in the MPF curve were observed. Significant correlations (r) between muscle oxygenation, blood volume, root mean square amplitude and mean power frequency were observed, which ranged from 0.72 to 0.99. These findings suggest that the fatigue resulting from sustained isometric exercise is related to a decrease in oxygenation and blood volume.  相似文献   

5.
To reduce resting blood pressure, a minimum isometric exercise training (IET) intensity has been suggested, but this is not known for short-term IET programmes. We therefore compared the effects of moderate- and low-intensity IET programmes on resting blood pressure. Forty normotensive participants (22.3 ± 3.4 years; 69.5 ± 15.5 kg; 170.2 ± 8.7 cm) were randomly assigned to groups of differing training intensities [20%EMGpeak (~23%MVC, maximum voluntary contraction, or 30%EMGpeak (~34%MVC)] or control group; 3 weeks of IET at 30%EMGpeak resulted in significant reductions in resting mean arterial pressure (e.g. ?3.9 ± 1.0 mmHg, P < 0.001), whereas 20%EMGpeak did not (?2.3 ± 2.9 mmHg; P > 0.05). Moreover, after pooling all female versus male participants, IET induced a 6.9-mmHg reduction in systolic blood pressure in female participants, but only a 1.5-mmHg reduction in systolic blood pressure in male participants, although the difference was not significant. An IET intensity between 20%EMGpeak and 30%EMGpeak is sufficient to elicit significant resting blood pressure reductions in a short-term training period (3 weeks). In addition, sexual dimorphism may exist in the magnitude of reductions, but further work is required to confirm this possibility, which could be important in understanding the mechanisms responsible.  相似文献   

6.
We investigated the oxygen-conserving potential of the human diving response by comparing trained breath-hold divers (BHDs) to non-divers (NDs) during simulated dynamic breath-holding (BH). Changes in haemodynamics [heart rate (HR), stroke volume (SV), cardiac output (CO)] and peripheral muscle oxygenation [oxyhaemoglobin ([HbO2]), deoxyhaemoglobin ([HHb]), total haemoglobin ([tHb]), tissue saturation index (TSI)] and peripheral oxygen saturation (SpO2) were continuously recorded during simulated dynamic BH. BHDs showed a breaking point in HR kinetics at mid-BH immediately preceding a more pronounced drop in HR (?0.86 bpm.%?1) while HR kinetics in NDs steadily decreased throughout BH (?0.47 bpm.%?1). By contrast, SV remained unchanged during BH in both groups (all P > 0.05). Near-infrared spectroscopy (NIRS) results (mean ± SD) expressed as percentage changes from the initial values showed a lower [HHb] increase for BHDs than for NDs at the cessation of BH (+24.0 ± 10.1 vs. +39.2 ± 9.6%, respectively; P < 0.05). As a result, BHDs showed a [tHb] drop that NDs did not at the end of BH (?7.3 ± 3.2 vs. ?3.0 ± 4.7%, respectively; P < 0.05). The most striking finding of the present study was that BHDs presented an increase in oxygen-conserving efficiency due to substantial shifts in both cardiac and peripheral haemodynamics during simulated BH. In addition, the kinetic-based approach we used provides further credence to the concept of an “oxygen-conserving breaking point” in the human diving response.  相似文献   

7.
Abstract

In this study, we examined the correlations between selected markers of isometric training intensity and subsequent reductions in resting blood pressure. Thirteen participants performed a discontinuous incremental isometric exercise test to volitional exhaustion at which point mean torque for the final 2-min stage (2min-torquepeak) and peak heart rate peak (HRpeak) were identified. Also, during 4 weeks of training (3 sessions per week, comprising 4 × 2 min bilateral leg isometric exercise at 95% HRpeak), heart rate (HRtrain), torque (Torquetrain), and changes in EMG amplitude (ΔEMGamp) and frequency (ΔEMGfreq) were determined. The markers of training intensity were: Torquetrain relative to the 2min-torquepeak (%2min-torquepeak), EMG relative to EMGpeak (%EMGpeak), HRtrain ΔEMGamp, ΔEMGfreq, and %MVC. Mean systolic (?4.9 mmHg) and arterial blood pressure (?2.7mmHg) reductions correlated with %2min-torquepeak (r = ?0.65, P = 0.02 and r = ?0.59, P = 0.03), ΔEMGamp (r = 0.66, P = 0.01 and r = 0.59, P = 0.03), ΔEMGfreq (r = ?0.67, P = 0.01 and r = ?0.64, P = 0.02), and %EMGpeak (systolic blood pressure only; r = ?0.63, P = 0.02). These markers best reflect the association between isometric training intensity and reduction in resting blood pressure observed after bilateral leg isometric exercise training.  相似文献   

8.
Abstract

The purpose of this study was to examine the psychosocial correlates of cardiorespiratory fitness ([Vdot]O2peak) and muscle strength in overweight and obese sedentary post-menopausal women. The study population consisted of 137 non-diabetic, sedentary overweight and obese post-menopausal women (mean age 57.7 years, s = 4.8; body mass index 32.4 kg · m?2, s = 4.6). At baseline we measured: (1) body composition using dual-energy X-ray absorptiometry; (2) visceral fat using computed tomography; (3) insulin sensitivity using the hyperinsulinaemic-euglycaemic clamp; (4) cardiorespiratory fitness; (5) muscle strength using the leg press exercise; and (6) psychosocial profile (quality of life, perceived stress, self-esteem, body-esteem, and perceived risk for developing chronic diseases) using validated questionnaires. Both [Vdot]O2peak and muscle strength were significantly correlated with quality of life (r = 0.29, P < 0.01 and r = 0.30, P < 0.01, respectively), and quality of life subscales for: physical functioning (r = 0.28, P < 0.01 and r = 0.22, P < 0.05, respectively), pain (r = 0.18, P < 0.05 and r = 0.23, P < 0.05, respectively), role functioning (r = 0.20, P < 0.05 and r = 0.24, P < 0.05, respectively), and perceived risks (r = ?0.24, P < 0.01 and r = ?0.30, P < 0.01, respectively). In addition, [Vdot]O2peak was significantly associated with positive health perceptions, greater body esteem, and less time watching television/video. Stepwise regression analysis showed that quality of life for health perceptions and for role functioning were independent predictors of [Vdot]O2peak and muscle strength, respectively. In conclusion, higher [Vdot]O2peak and muscle strength are associated with a favourable psychosocial profile, and the psychosocial correlates of [Vdot]O2peak were different from those of muscle strength. Furthermore, psychosocial factors could be predictors of [Vdot]O2peak and muscle strength in our cohort of overweight and obese sedentary post-menopausal women.  相似文献   

9.
Abstract

The objective of this study was to investigate the effects of wearing compression socks (CS) on performance indicators and physiological responses during prolonged trail running. Eleven trained runners completed a 15.6 km trail run at a competition intensity whilst wearing or not wearing CS. Counter movement jump, maximal voluntary contraction and the oxygenation profile of vastus lateralis muscle using near-infrared spectroscopy (NIRS) method were measured before and following exercise. Run time, heart rate (HR), blood lactate concentration and ratings of perceived exertion were evaluated during the CS and non-CS sessions. No significant difference in any dependent variables was observed during the run sessions. Run times were 5681.1±503.5 and 5696.7±530.7 s for the non-CS and CS conditions, respectively. The relative intensity during CS and non-CS runs corresponded to a range of 90.5–91.5% HRmax. Although NIRS measurements such as muscle oxygen uptake and muscle blood flow significantly increased following exercise (+57.7% and + 42.6%,+59.2% and + 32.4%, respectively for the CS and non-CS sessions, P<0.05), there was no difference between the run conditions. The findings suggest that competitive runners do not gain any practical or physiological benefits from wearing CS during prolonged off-road running.  相似文献   

10.
ABSTRACT

Hamstring strain injury (HSI) rates are higher for males vs. females. This cross-sectional study investigated if inherent differences in biceps femoris long head (BFLH) fascicle length (Lf) exist between recreationally active males and females (i.e., individuals without specific training practice history). Twenty-four young healthy participants (12 males; 12 females) had their BFLH muscle architecture (Lf, pennation angle [θp], and muscle thickness [MT]) measured using B-mode ultrasonography. Eccentric and isometric knee flexion strength were also assessed. BFLH Lf did not differ between sexes when expressed in absolute terms (males, 81.5 ± 14.7 mm; females, 73.6 ± 15.9 mm, P = 0.220, effect size (ES) = 0.52) or relative to femur length (0.140 ≤ P ≤ 0.220, ES = 0.63). Similarly, BFLH θp did not differ between sexes (P = 0.650) but BFLH MT was 18.9% larger for males vs. females (P = 0.024, ES = 0.99). Isometric and eccentric knee flexion strength was greater for males vs. females in absolute terms ([both] P < 0.001, 2.00 ≤ ES ≤ 2.27) and relative to body mass ([both] P < 0.001, 1.93 ≤ ES ≤ 2.13). In conclusion, factors other than BFLH Lf seem likely to be implicated in higher male vs. female HSI rates.  相似文献   

11.
Abstract

In this study, we examine the effect of exercise on the time and flow characteristics of the respiratory cycle profile at the point of volitional exercise termination. Eight males (mean age 29 years, s = 10; body mass 74 kg, s = 7; height 1.75 m, s = 0.04) undertook a cycle test to volitional exhaustion on a cycle ergometer, which allowed peak oxygen uptake ([Vdot]O2peak) to be measured (mean 51 ml · kg?1 · min?1, s = 7). At a later date, two sub-maximal tests to volitional exhaustion were completed in a random order at 76% (s = 6) and 86%[Vdot]O2peak (s = 7). As expected, the magnitude of the respiratory flow and time characteristics varied with the three exercise intensities, as did the point of exercise termination and terminal ventilation rates, which varied from 7 to 27 min and 112 to 132 litres · min?1 respectively. More importantly, however, at exercise termination some of the characteristics were similar, particularly the breathing frequency (at termination 49 breaths · min?1), the ratio between inspiration and total breath time (0.5), and the later occurrence of peak inspiratory flow (0.24 – 0.48 s). The coincident unity of these time and flow profile characteristics at exercise termination illustrates how the integration of timing and flow during breathing influence exercise capacity in non-elite athletes.  相似文献   

12.
Abstract

The aim of this study was to establish a graded exercise test protocol for determining the peak physiological responses of female outrigger canoeists. Seventeen trained female outrigger canoeists completed two outrigger ergometer graded exercise test protocols in random order: (1) 25 W power output for 2 min increasing by 7.5 W every minute until exhaustion; and (2) 25 W power output for 2 min increasing by 15 W every 2 min to exhaustion. Heart rate and power output were recorded every 15 s. Expired air was collected continuously and sampled for analysis at 15-s intervals, while blood lactate concentration was measured immediately after and 3, 5, and 7 min after exercise. The peak physiological and performance variables examined included peak oxygen uptake ([Vdot]O2peak), minute ventilation, tidal volume, ventilatory thresholds 1 and 2, respiratory rate, respiratory exchange ratio, heart rate, blood lactate concentration, power output, performance time, and time to [Vdot]O2peak. There were no significant differences in peak physiological responses, ventilatory thresholds or performance variables between the two graded exercise test protocols. Despite no significant differences between protocols, due to the large limits of agreement evident between protocols for the peak physiological responses, it is recommended that the same protocol be used for all comparison testing to minimize intra-individual variability of results.  相似文献   

13.
To examine the reliability for peak responses of oxygen consumption (VO2peak) in relative (ml · kg-1 · min-1) and absolute (L/min-1) measures, as well as peak heart rate (HRpeak) during deep water running (DWR), 26 participants (12 women, 14 men) completed two DWR maximal graded exercise tests. To estimate the validity of the peak responses during DWR, a comparison to a treadmill running (TMR) graded exercise test (GXT) was completed. Test order was randomized. The DWR GXT utilized a system of weights and pulleys to increase intensity of exercise. Reliability of the DWR test for the total group was estimated using a repeated measures one-way analysis of variance (ANOVA) for VO2peak (ml · kg-1 · min-1, R = .96; L/min-1, R = .97) and HRpeak (R = .90). There were no significant differences (p > .05) between the two DWR tests for men or women for the means of VO2peak in relative units (men: 50.5 vs. 52.0 ml · kg-1 · min-1; women: 37.1 vs. 36.8 ml · kg-1 · min-1), or absolute units (men: 4.1 vs. 4.1 L/min-1; women: 2.2 vs. 2.2 L/min-1), or HR (men: 174 vs. 175 beats per minute (bpm); women: 181 vs. 183 bpm). There was a significant correlation between the average of the two DWR tests and TMR for the total group for VO2peak for relative (r = .88, p = .001) and absolute (r = .93, p = .001) measures as well as HRpeak (r = .64, p = .001). Peak responses during the DWR protocol were judged to be reliable. Also, the correlation for the variables between DWR and TMR indicates a positive relation between peak responses. The correlation suggests validity of predicting TMR peak responses from DWR peak responses; however, this conclusion may be questionable due to the low sample size and the large systemic differences between tests. Finally, HRpeak and VO2peak were lower during DWR than TMR for both men and women.  相似文献   

14.
This study compared the responses of two priming exercises of similar fatigue on the adjustment of the oxygen uptake time constant (τV?O2) in cycling. Ten healthy young adults (25 ± 3 yr) performed: three step transitions from a 20-W baseline to the power output (PO) below the gas exchange threshold (MOD, MODPRE); a 3-min bout (P3MIN) at 90% of peak PO (POpeak), followed by MOD (MOD3MIN); and a 6-min bout (P6MIN) at 80% of POpeak, followed by MOD (MOD6MIN). The O2 supply-to-O2 demand ([HHb]/V?O2) ratio was calculated for MODPRE, MOD3MIN, and MOD6MIN. Neuromuscular fatigue was measured isometrically pre- and post-priming exercise. Reductions in maximal voluntary contraction (?29 ± 6 vs ?34 ± 7%) and high-frequency doublet amplitude (?48 ± 13 vs ?43 ± 11%) were not significantly different between P3MIN vs P6MIN, suggesting similar fatigue. τV?O2 for MOD3MIN and MOD6MIN were similar, being ~25% smaller than MODPRE. The [HHb]/V?O2 ratio was significantly greater in MODPRE (1.13 ± 0.12) compared to MOD3MIN (1.02 ± 0.04) and MOD6MIN (1.02 ± 0.04). This study showed that priming exercise of shorter duration and higher intensity, was sufficient to accelerate V?O2 kinetics similarly to that observed subsequent to P6MIN when the muscle fatigue was similar.  相似文献   

15.
The aim of this study was to determine the influence of swim intensity on acute responses to dynamic apnoea. 9 swimmers performed one 50 m front crawl trial in four different conditions: at 400 m velocity (V400) with normal breathing (NB), at V400 in complete apnoea (Ap), at maximal velocity (Vmax) with NB and at Vmax in Ap. Peak heart rate (HRpeak), blood lactate concentration after exercise (Lacpost ex) and Borg rating of perceived exertion (RPE) were measured. Arterial oxygen saturation (SpO2) was monitored with a pulse oximeter at forehead level during and after exercise. In Ap, swimming at V400 induced a significantly lower HRpeak and Lacpost ex than swimming at Vmax whilst RPE and the kinetics of SpO2 were not different at V400 and at Vmax. The minimal value of SpO2 in Ap was reached 10 to 11 s after the end of V400 and Vmax (81.7 ± 10.1% and 84.4 ± 10.6%, respectively). Swimming a 50 m front crawl in Ap resulted in a large decrease in SpO2 which occurred only after the cessation of exercise. The higher duration of apnoea during submaximal exercise could explain why SpO2 and RPE reached the same values as for maximal exercise.?  相似文献   

16.
The purpose of this study was to evaluate the validity of prediction equations for estimating maximal oxygen uptake (VO2peak) based on the PACER test and different adiposity indicators in Mexican youth. A convenience sample of youth aged 9–18 years from schools in Mexico City was recruited. VO2peak was evaluated with a laboratory exercise test on a treadmill and using a gas analyser and with the 20-m PACER test guidelines. The sample was randomly divided to develop new equations (n = 220) and to evaluate their validity (n = 106). Prediction equations of VO2peak were developed using multiple linear regression models. The adiposity indicators were BMI, waist circumference and body fat. The validity of the new and previously published equations was evaluated based on linear regression models, intra-class coefficient, Akaike’s information criterion, mean absolute percentage error and Bland-Altman graphs. Equations with waist circumference and body fat performed better than those with BMI and without any anthropometric indicator. The accuracy of the developed equations (R2 = 57.0%–59.50%) was higher than that of previously published equations (R2 = 24.1%–56.0%). The new equations had lower bias in estimating VO2peak. In Mexican youth, the estimation of VO2peak from the 20-m PACER test is more accurate after including waist circumference or body fat than with BMI.  相似文献   

17.
Abstract

Respiratory muscle fatigue has been reported following short bouts of high-intensity exercise, and prolonged, moderate-intensity exercise, as evidenced by decrements in inspiratory and expiratory mouth pressures. However, links to functionally relevant outcomes such as breathing effort have been lacking. The present study examined dyspnoea and leg fatigue during a treadmill marathon in nine experienced runners. Maximal inspiratory and expiratory pressure, peak inspiratory and expiratory flow, forced vital capacity, and forced expiratory volume in one second were assessed before, immediately after, and four and 24 hours after a marathon. During the run, leg effort was rated higher than respiratory effort from 18 through 42 km (P < 0.05). Immediately after the marathon, there were significant decreases in maximal inspiratory pressure and peak inspiratory flow (from 118 ± 20 cm H2O and 6.3 ± 1.4 litres · s?1 to 100 ± 22 cm H2O and 4.9 ± 1.5 litres · s?1 respectively; P < 0.01), while expiratory function remained unchanged. Leg maximum voluntary contraction force was significantly lower post-marathon. Breathing effort correlated significantly with leg fatigue (r = 0.69), but not inspiratory muscle fatigue. Our results confirm that prolonged moderate-intensity exercise induces inspiratory muscle fatigue. Furthermore, they suggest that the relative intensity of inspiratory muscle work during exercise makes some contribution to leg fatigue.  相似文献   

18.
This study compared the effects of 12-week sprint interval training (SIT), high-intensity interval training (HIIT), and moderate-intensity continuous training (MICT) on cardiorespiratory fitness (V?O2peak), body mass and insulin sensitivity in overweight females. Forty-two overweight women (age 21.2 ± 1.4 years, BMI 26.3 ± 2.5 kg·m?2) were randomized to the groups of SIT (80 × 6-s sprints + 9-s rest), and isoenergetic (300KJ) HIIT (~9 × 4-min cycling at 90% V?O2peak + 3-min rest) and MICT (cycling at 60% V?O2peak for ~ 61-min). Training intervention was performed 3 d·week?1 for 12 weeks. After intervention, all three groups induced the same improvement in V?O2peak (~ +25%, p < 0.001) and a similar reduction in body mass (~ – 5%, p < 0.001). Insulin sensitivity and fasting insulin levels were improved significantly on post-training measures in SIT and HIIT by ~26% and ~39% (p < 0.01), respectively, but remain unchanged in MICT. In contrast, fasting glucose levels were only reduced with MICT (p < 0.01). The three training strategies are equally effective in improving V?O2peak and reducing body mass, however, the SIT is time-efficient. High-intensity training (i.e. SIT and HIIT) seems to be more beneficial than MICT in improving insulin sensitivity.

Abbreviations: BMI: body mass index; CVD: cardiovascular disease; HIEG: hyperinsulinaemic euglycaemic glucose; HIIT: high-intensity interval training; HOMA-IR: homeostasis model assessment of insulin resistance; HR: heart rate; MICT: moderate-intensity continuous training; RPE: ratings of perceived exertion; SIT: sprint interval training; T2D: type 2 diabetes; V?O2peak: peak oxygen consumption  相似文献   


19.
Introduction: The Moxy is a novel, cutaneously placed muscle oxygen monitor which claims to measure local oxygen saturation (SmO2) and total haemoglobin (THb) using near-infrared spectroscopy. If shown to be reliable, its data storage and telemetric capability will be useful for assessing localised O2 usage during field-based exercise. This study investigated the reliability of the Moxy during cycling and assessed the correlations between its measurements, whole-body O2 consumption (VO2) and heart rate (HR). Methods: Ten highly trained cyclists performed an incremental, step-wise cycling protocol on two occasions while wearing the Moxy. SmO2, THb, VO2 and HR were recorded in the final minute of each five-minute stage. Data were analysed using Spearman’s Order-Rank Coefficient (SROC), Intraclass Correlation (ICC), and Coefficient of Variance (COV). Significance was set at p?≤?.05. Results: SmO2 showed a ‘strong’ or ‘very large’ correlation between trials (SROC: r?=?0.842–0.993, ICC: r?=?0.773–0.992, p?≤?.01) and was moderately correlated with VO2 and HR (r?=??0.71–0.73, p?≤?.01). SmO2 showed a moderate to high reliability at low intensities, but this decreased as relative exercise intensity increased. THb showed poor correlations between tests and with the other measured variables, but was highly reliable at all power outputs. Conclusions: The Moxy is a reliable device to measure SmO2 at low to moderate intensities, but at higher intensities, greater variation in measurements occurs, likely due to tissue ischaemia or increased movement artefacts due to more frequent muscular contractions. THb has low variation during exercise, and does not appear to be a valid indicator of muscle oxygenation.  相似文献   

20.
This study compares test-retest reliability and peak exercise responses from ramp-incremented (RAMP) and maximal perceptually-regulated (PRETmax) exercise tests during arm crank exercise in individuals reliant on manual wheelchair propulsion (MWP). Ten untrained participants completed four trials over 2-weeks (two RAMP (0–40 W + 5–10 W · min?1) trials and two PRETmax. PRETmax consisted of five, 2-min stages performed at Ratings of Perceived Exertion (RPE) 11, 13, 15, 17 and 20). Participants freely changed the power output to match the required RPE. Gas exchange variables, heart rate, power output, RPE and affect were determined throughout trials. The V?O2peak from RAMP (14.8 ± 5.5 ml · kg?1 · min?1) and PRETmax (13.9 ± 5.2 ml · kg?1 · min?1) trials were not different (P = 0.08). Measurement error was 1.7 and 2.2 ml · kg?1 · min?1 and coefficient of variation 5.9% and 8.1% for measuring V?O2peak from RAMP and PRETmax, respectively. Affect was more positive at RPE 13 (P = 0.02), 15 (P = 0.01) and 17 (P = 0.01) during PRETmax. Findings suggest that PRETmax can be used to measure V?O2peak in participants reliant on MWP and leads to a more positive affective response compared to RAMP.  相似文献   

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