Ventilatory Threshold during Wheelchair Exercise in Untrained and Endurance-Trained Subjects with Quadriplegia

1995 ◽  
Vol 12 (4) ◽  
pp. 333-343 ◽  
Author(s):  
Yagesh N. Bhambhani ◽  
Robert S. Burnham ◽  
Gary D. Wheeler ◽  
Peter Eriksson ◽  
Leona J. Holland ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Oxygen Uptake ◽  
Endurance Training ◽  
Ventilatory Threshold ◽  
Reliability Coefficient ◽  
Trained Subjects ◽  
Respiratory Gas Exchange ◽  
Significant Difference ◽  
Roller System ◽  
Male Subjects

In this study we compared the ventilatory threshold (VT) between 8 untrained and 8 endurance-trained males with quadriplegia during simulated wheelchair exercise. Each subject completed an incremental velocity test in his personal wheelchair mounted on a customized roller system designed to provide velocity and distance feedback. VT was identified by two trained evaluators using established respiratory gas exchange criteria. A significant interevaluator reliability coefficient of .90 (p < .01) was observed for the detection of VT. Relative oxygen uptake (V̇O2, ml · kg-1 · min-1) at VT and peak V̇O2 were significantly (p < .05) higher in the endurance-trained compared to untrained subjects. However, no significant difference (p > .05) was observed between the two groups when VT was expressed as a percentage of peak V̇O2. Significant correlations of .86 and .81 (p < .01) were observed between VT and peak V̇O2 in the untrained and trained groups, respectively. It was concluded that endurance training improves both VT and peak V̇O2 during wheelchair exercise in male subjects with quadriplegia but does not improve VT when it is expressed relative to peak V̇O2.

scholarly journals Coca chewing for exercise: hormonal and metabolic responses of nonhabitual chewers

1996 ◽  
Vol 81 (5) ◽  
pp. 1901-1907 ◽  
Author(s):  
Roland Favier ◽  
Esperanza Caceres ◽  
Laurent Guillon ◽  
Brigitte Sempore ◽  
Michel Sauvain ◽  
...  
Keyword(s):  
Heart Rate ◽  
Gas Exchange ◽  
Oxygen Uptake ◽  
Metabolic Responses ◽  
Physiological Data ◽  
Respiratory Gas Exchange ◽  
Gum Chewing ◽  
Arterial Blood ◽  
Before And After ◽  
Exercise Induced

Favier, Roland, Esperanza Caceres, Laurent Guillon, Brigitte Sempore, Michel Sauvain, Harry Koubi, and Hilde Spielvogel. Coca chewing for exercise: hormonal and metabolic responses of nonhabitual chewers. J. Appl. Physiol. 81(5): 1901–1907, 1996.—To determine the effects of acute coca use on the hormonal and metabolic responses to exercise, 12 healthy nonhabitual coca users were submitted twice to steady-state exercise (∼75% maximal O2 uptake). On one occasion, they were asked to chew 15 g of coca leaves 1 h before exercise, whereas on the other occasion, exercise was performed after 1 h of chewing a sugar-free chewing gum. Plasma epinephrine, norepinephrine, insulin, glucagon, and metabolites (glucose, lactate, glycerol, and free fatty acids) were determined at rest before and after coca chewing and during the 5th, 15th, 30th, and 60th min of exercise. Simultaneously to these determinations, cardiorespiratory variables (heart rate, mean arterial blood pressure, oxygen uptake, and respiratory gas exchange ratio) were also measured. At rest, coca chewing had no effect on plasma hormonal and metabolic levels except for a significantly reduced insulin concentration. During exercise, the oxygen uptake, heart rate, and respiratory gas exchange ratio were significantly increased in the coca-chewing trial compared with the control (gum-chewing) test. The exercise-induced drop in plasma glucose and insulin was prevented by prior coca chewing. These results contrast with previous data obtained in chronic coca users who display during prolonged submaximal exercise an exaggerated plasma sympathetic response, an enhanced availability and utilization of fat (R. Favier, E. Caceres, H. Koubi, B. Sempore, M. Sauvain, and H. Spielvogel. J. Appl. Physiol. 80: 650–655, 1996). We conclude that, whereas coca chewing might affect glucose homeostasis during exercise, none of the physiological data provided by this study would suggest that acute coca chewing in nonhabitual users could enhance tolerance to exercise.

Increased hepatic glucose production response to glucagon in trained subjects

1998 ◽  
Vol 274 (1) ◽  
pp. E23-E28 ◽  
Author(s):  
Réjean Drouin ◽  
Carole Lavoie ◽  
Josée Bourque ◽  
Francine Ducros ◽  
Danielle Poisson ◽  
...  
Keyword(s):  
Endurance Training ◽  
Hepatic Glucose Production ◽  
Area Under The Curve ◽  
Glucose Production ◽  
Trained Subjects ◽  
Endogenous Insulin ◽  
Hepatic Glucose ◽  
Glucagon And Insulin ◽  
The Impact ◽  
Male Subjects

This study was designed to characterize the impact of endurance training on the hepatic response to glucagon. We measured the effect of glucagon on hepatic glucose production (HGP) in resting trained ( n = 8) and untrained ( n = 8) healthy male subjects (maximal rate of O2 consumption: 65.9 ± 1.6 vs. 46.8 ± 0.6 ml O2 ⋅ kg−1 ⋅ min−1, respectively, P < 0.001). Endogenous insulin and glucagon were suppressed by somatostatin (somatotropin release-inhibiting hormone) infusion (450 μg/h) over 4 h. Insulin (0.15 mU ⋅ kg−1 ⋅ min−1) was infused throughout the study, and glucagon (1.5 ng ⋅ kg−1 ⋅ min−1) was infused over the last 2 h. During the latter period, plasma glucagon and insulin remained constant at 138.2 ± 3.1 vs. 145.3 ± 2.1 ng/l and at 95.5 ± 4.5 vs. 96.2 ± 1.9 pmol/l in trained and untrained subjects, respectively. Plasma glucose increased and peaked at 11.4 ± 1.1 mmol/l in trained subjects and at 8.9 ± 0.8 mmol/l in untrained subjects ( P < 0.001). During glucagon stimulation, the mean increase in HGP area under the curve was 15.8 ± 2.8 mol ⋅ kg−1 ⋅ min−1in trained subjects compared with 7.4 ± 1.6 mol ⋅ kg−1 ⋅ min−1in untrained subjects ( P < 0.01) over the first hour and declined to 6.8 ± 2.8 and 4.9 ± 1.4 mol ⋅ kg−1 ⋅ min−1during the second hour. In conclusion, these observations indicate that endurance training is associated with an increase in HGP in response to physiological levels of glucagon, thus suggesting an increase in hepatic glucagon sensitivity.

scholarly journals Running velocity at the ventilatory threshold and at VO2max, before and after the eight-week cardiovascular endurance training

2005 ◽  
Vol 58 (1-2) ◽  
pp. 27-31
Author(s):  
Stanimir Stojiljkovic ◽  
Sanja Mazic ◽  
Dejan Nesic ◽  
Sasko Velkovski ◽  
Dusan Mitrovic
Keyword(s):  
Endurance Training ◽  
Ventilatory Threshold ◽  
Exercise Program ◽  
Test Results ◽  
Final Test ◽  
Experimental Conditions ◽  
Cardiovascular Endurance ◽  
Before And After ◽  
Test Velocity ◽  
Male Subjects

Introduction The purpose of this research was to compare changes in running velocity at ventilatory threshold with the veliocity at VO2max, before and after the eight-week exercise program. Material and methods 32 male subjects (age: 22.3? 2.5 years, height: 179.8? 7.6 cm, body mass: 76.8? 9.0 kg) performed a progressive test for ventilatory threshold (VT) measurement and VO2max on treadmill. After 8 weeks of endurance training (3 times per week, 30 to 70 min, in different zones in respect to the ventilatory threshold) the performed the same test. Results Running velocity at ventilatory threshold increased significantly (p=0.000I), between initial and final measurements (10.88?2.09, 12.94? 1.90 km/h, respectively): as well as at VO2max H4.63?1.86, 16.44?1.59 km/h, respectively). At the initial test, velocity at ventilatory threshold was 74.11% of VO2max. At the final test, velocity at ventilatory threshold was 78.43% of VO2max. Running velocity at ventilatory threshold has significantly increased at final test (p=0.001). Discussion Running velocity at ventilatory threshold has significantly increased after eight weeks of endurance training (p -0.001), when expressed in absolute values and percentage of velocity at vo2max. Conclusion Comparison between the initial and final test demonstrated a significant increase of observed variables, under experimental conditions: at final test running velocity has increased at ventilatory threshold, in respect to absolute values and expressed as percentage at VO2max. .

Performance of runners and swimmers after four weeks of intermittent hypobaric hypoxic exposure plus sea level training

2007 ◽  
Vol 103 (5) ◽  
pp. 1523-1535 ◽  
Author(s):  
Ferran A. Rodríguez ◽  
Martin J. Truijens ◽  
Nathan E. Townsend ◽  
James Stray-Gundersen ◽  
Christopher J. Gore ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Sea Level ◽  
Oxygen Transport ◽  
Hypobaric Hypoxia ◽  
Ventilatory Threshold ◽  
Controlled Trial ◽  
Intervention Group ◽  
Sport Performance ◽  
Hypoxic Exposure ◽  
Significant Difference

This double-blind, randomized, placebo-controlled trial examined the effects of 4 wk of resting exposure to intermittent hypobaric hypoxia (IHE, 3 h/day, 5 days/wk at 4,000–5,500 m) or normoxia combined with training at sea level on performance and maximal oxygen transport in athletes. Twenty-three trained swimmers and runners completed duplicate baseline time trials (100/400-m swims, or 3-km run) and measures for maximal oxygen uptake (V̇O2max), ventilation (V̇Emax), and heart rate (HRmax) and the oxygen uptake at the ventilatory threshold (V̇O2 at VT) during incremental treadmill or swimming flume tests. Subjects were matched for sex, sport, performance, and training status and divided randomly between hypobaric hypoxia (Hypo, n = 11) and normobaric normoxia (Norm, n = 12) groups. All tests were repeated within the first (Post1) and third weeks (Post2) after the intervention. Time-trial performance did not improve in either group. We could not detect a significant difference between groups for a change in V̇O2max, V̇Emax, HRmax, or V̇O2 at VT after the intervention (group × test interaction P = 0.31, 0.24, 0.26, and 0.12, respectively). When runners and swimmers were considered separately, Hypo swimmers appeared to increase V̇O2max (+6.2%, interaction P = 0.07) at Post2 following a precompetition taper and increased V̇O2 at VT (+8.9 and +12.1%, interaction P = 0.007 and 0.006, at Post1 and Post2). We conclude that this “dose” of IHE was not sufficient to improve performance or oxygen transport in this heterogeneous group of athletes. Whether there are potential benefits of this regimen for specific sports or training/tapering strategies may require further study.

Impeding O2 unloading in muscle delays oxygen uptake response to exercise onset in humans

1999 ◽  
Vol 277 (5) ◽  
pp. R1274-R1281 ◽  
Author(s):  
Naoyuki Hayashi ◽  
Mutsuhisa Ishihara ◽  
Ayumu Tanaka ◽  
Takayoshi Yoshida
Keyword(s):  
Oxygen Uptake ◽  
Time Constant ◽  
Ventilatory Threshold ◽  
Oxygen Dissociation Curve ◽  
Dissociation Curve ◽  
Leftward Shift ◽  
Oxygen Dissociation ◽  
Significant Difference ◽  
Ergometer Exercise ◽  
Exercise Onset

We tested whether the leftward shift of the oxygen dissociation curve of hemoglobin with hyperpnea delays the oxygen uptake (V˙o 2) response to the onset of exercise. Six male subjects performed cycle ergometer exercise at a work rate corresponding to 80% of the ventilatory threshold (VT) V˙o 2 of each individual after 3 min of 20-W cycling under eupnea [control (Con) trial]. A hyperpnea procedure (minute ventilation = 60 l/min) was undertaken for 2 min before and during 80% VT exercise in hypocapnia (Hypo) and normocapnia (Normo) trials. In the Normo trial, the inspired CO2 fraction was 3% to prevent hypocapnia. The subjects completed two repetitions of each trial. To determine the kinetic variables ofV˙o 2 and heart rate (HR) at the onset of exercise, a nonlinear least-squares fitting was applied to the data averaged from two repetitions by a monoexponential model. The end-tidal CO2 partial pressure before the onset of exercise was significantly lower in the Hypo trial than in the Con and Normo trials (22 ± 1 vs. 38 ± 3 and 36 ± 1 mmHg, respectively, P < 0.05). The time constant ofV˙o 2 and HR was significantly longer in the Normo trial (28 ± 7 and 39 ± 18 s, respectively) than in the Con trial (21 ± 7, 34 ± 16 s, respectively, P < 0.05). TheV˙o 2 time constant of the Hypo trial (37 ± 12 s) was significantly longer than that of the Normo trial, although no significant difference in the HR time constant was seen (Hypo, 41 ± 28 s). These findings suggested that respiratory alkalosis delayed the kinetics of oxygen diffusion in active muscle as a result of the leftward shift of the oxygen dissociation curve of hemoglobin. This supports an important role for hemoglobin-O2 offloading in setting the V˙o 2 kinetics at exercise onset.

scholarly journals Agreement analysis between critical power and intensity corresponding to 50% in cycling exercise

2016 ◽  
Vol 18 (2) ◽  
pp. 197 ◽  
Author(s):  
Kristopher Mendes de Souza ◽  
Ricardo Dantas de Lucas ◽  
Paulo Cesar do Nascimento Salvador ◽  
Lucas Crescenti Abdalla Saad Helal ◽  
Luiz Guilherme Antonacci Guglielmo ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Lactate Threshold ◽  
Critical Power ◽  
Limits Of Agreement ◽  
Cycling Exercise ◽  
Significant Difference ◽  
The Mean ◽  
The Difference ◽  
Male Subjects ◽  
Level Of Agreement

DOI: http://dx.doi.org/10.5007/1980-0037.2016v18n2p197 The purpose of this study was to determine the level of agreement between critical power (CP) and intensity corresponding to 50% of the difference (50% Δ) between oxygen uptake (VO2) at lactate threshold (LT) and maximal oxygen uptake (VO2max) in untrained subjects during cycling exercise. Fifteen healthy male subjects (age: 26.0 ± 3.5 years; body weight: 76.6 ± 10.4 kg; height: 178.2 ± 7.6 cm) volunteered to participate in the study. Each subject performed a series of tests to determine LT, VO2LT, CP, VO2CP, 50% Δ, VO250% Δ, and VO2max. The values of LT, VO2LT, CP, VO2CP, 50% Δ, VO250% Δ and VO2max were 109 ± 15 W, 1.84 ± 0.23 L.min-1, 207 ± 17 W, 2.78 ± 0.27 L.min-1, 206 ± 19 W, 2.77 ± 0.29 L.min-1, and 3.71 ± 0.49 L.min-1, respectively. No significant difference was found between CP and 50% Δ (t = 0.16; p = 0.87) or between VO2CP and VO250% Δ (t = 0.12; p = 0.90). However, the bias ± 95% limits of agreement for comparison between CP and 50% Δ and between VO2CP and VO250% Δ were 1 ± 27 W (0.3 ± 14.1%) and 0.01 ± 0.24 L.min-1 (0.2 ± 8.9%), respectively. In summary, the mean CP and 50% Δ values were not significantly different. However, considering the limits of agreement between the two intensities, CP estimated based on 50% Δ might result in a remarkable error when the absolute variability of individual differences is taken into account

The Effect of Prior Endurance Training on Nap Sleep Patterns

2010 ◽  
Vol 5 (1) ◽  
pp. 87-97 ◽  
Author(s):  
Daniel J. Davies ◽  
Kenneth S. Graham ◽  
Chin Moi Chow
Keyword(s):  
Endurance Training ◽  
Slow Wave Sleep ◽  
Time Interval ◽  
Circadian Timing ◽  
Training Time ◽  
Significant Difference ◽  
Subjective Measurements ◽  
Daytime Nap ◽  
Male Subjects

Purpose:The use of daytime napping as a recovery tool following exercise is virtually unexplored. The objective of this study was to assess the quality of daytime nap sleep following endurance training in an athletic population, and to appraise the optimal circadian timing of the nap and the time interval between training and the nap.Methods:Six physically trained male subjects (22.5 ± 2.4 y) performed four separate standardized 90-min endurance training sessions followed by a 90-min daytime nap either 1 or 2 h after training (time interval), commencing at either 10:30 or 11:30 (circadian timing). During the nap, sleep was monitored using polysomnography. Subjective measurements of sleep quality, alertness and preparedness to train following a nap were recorded using a visual analog scale.Results:The duration of slow wave sleep (SWS) was significantly greater during the 11:30 naps (13.7 ± 9.0 min) compared with the 10:30 naps (6.9 ± 8.8 min) (P = .049). There was no significant difference in SWS duration between a 1-h (10.6 ± 10.2 min) or 2-h (10.0 ± 9.0 min) time interval between training and the nap (P = .82). No other sleep variables differed significantly according to circadian timing or time interval.Conclusion:Recovery naps commenced later in the morning contain more SWS than earlier naps. The data imply that daytime naps have a potential role as a valuable recovery tool following endurance exercise, given the suggested energy restorative functions of SWS.

Muscle Oxygenation Trends During Dynamic Exercise Measured by Near Infrared Spectroscopy

2004 ◽  
Vol 29 (4) ◽  
pp. 504-523 ◽  
Author(s):  
Yagesh N. Bhambhani
Keyword(s):  
Oxygen Uptake ◽  
Blood Volume ◽  
Near Infrared ◽  
Ventilatory Threshold ◽  
Biceps Brachii ◽  
Vastus Lateralis ◽  
Dynamic Exercise ◽  
Muscle Oxygenation ◽  
Muscle Deoxygenation ◽  
Significant Difference

During the last decade, NIRS has been used extensively to evaluate the changes in muscle oxygenation and blood volume during a variety of exercise modes. The important findings from this research are as follows: (a) There is a strong correlation between the lactate (ventilatory) threshold during incremental cycle exercise and the exaggerated reduction in muscle oxygenation measured by NIRS. (b) The delay in steady-state oxygen uptake during constant work rate exercise at intensities above the lactate/ventilatory threshold is closely related to changes in muscle oxygenation measured by NIRS. (c) The degree of muscle deoxygenation at the same absolute oxygen uptake is significantly lower in older persons compared younger persons; however, these changes are negated when muscle oxygenation is expressed relative to maximal oxygen uptake values. (d) There is no significant difference between the rate of biceps brachii and vastus lateralis deoxygenation during arm cranking and leg cycling exercise, respectively, in males and females. (e) Muscle deoxygenation trends recorded during short duration, high-intensity exercise such as the Wingate test indicate that there is a substantial degree of aerobic metabolism during such exercise. Recent studies that have used NIRS at multiple sites, such as brain and muscle tissue, provide useful information pertaining to the regional changes in oxygen availability in these tissues during dynamic exercise. Key words: blood volume, noninvasive measurement

Plasma volume and intravascular protein masses in trained boys and fit young men

1977 ◽  
Vol 43 (6) ◽  
pp. 1085-1088 ◽  
Author(s):  
G. Koch ◽  
L. Rocker
Keyword(s):  
Physical Activity ◽  
Oxygen Uptake ◽  
Endurance Training ◽  
Plasma Volume ◽  
Maximal Oxygen Uptake ◽  
Binding Capacity ◽  
Vo2 Max ◽  
Water Binding ◽  
Body Dimensions ◽  
Significant Difference

Plasma volumes and intravascular protein masses were measured in eight well-trained boys (VO2 max = 59.6 +/- 6.5 ml/kg body wt) aged 13–15 yr and compared with two groups of adult athletes aged 17–20 yr (VO2 max = 61.8 +/- 3.4 ml/kg body wt) and 24–30 yr (VO2 max = 63.3 +/- 4.1 ml/kg body wt), respectively. The trained boys had larger plasma volumes and increased intravascular masses of albumin and hepatogenic globulins as compared with values available for children with normal physical activity. There was no significant difference between the boys and the adults concerning maximal oxygen uptake, plasma volume, albumin, immunoglobins, and haptoglobin, when allowance was made for differences in body dimensions; probably due to the young age, however, the boys had considerably higher relative alpha2-macroglobulin and transferrin masses. Endurance training apparently elicits the same response of the plasma protein system regardless of age, at least after pubertal age has been attained. The overall effect of these changes implies an increase of the water binding capacity of the plasma

Exercise training in normobaric hypoxia in endurance runners. III. Muscular adjustments of selected gene transcripts

2006 ◽  
Vol 100 (4) ◽  
pp. 1258-1266 ◽  
Author(s):  
Joffrey Zoll ◽  
Elodie Ponsot ◽  
Stéphane Dufour ◽  
Stéphane Doutreleau ◽  
Renée Ventura-Clapier ◽  
...  
Keyword(s):  
Carbonic Anhydrase ◽  
Exercise Training ◽  
Oxygen Uptake ◽  
Glucose Transporter ◽  
Ventilatory Threshold ◽  
Normobaric Hypoxia ◽  
Time To Exhaustion ◽  
Mrna Levels ◽  
Glucose Transporter 4 ◽  
Trained Subjects

We hypothesized that specific muscular transcript level adaptations participate in the improvement of endurance performances following intermittent hypoxia training in endurance-trained subjects. Fifteen male high-level, long-distance runners integrated a modified living low-training high program comprising two weekly controlled training sessions performed at the second ventilatory threshold for 6 wk into their normal training schedule. The athletes were randomly assigned to either a normoxic (Nor) (inspired O2 fraction = 20.9%, n = 6) or a hypoxic group exercising under normobaric hypoxia (Hyp) (inspired O2 fraction = 14.5%, n = 9). Oxygen uptake and speed at second ventilatory threshold, maximal oxygen uptake (V̇o2 max), and time to exhaustion (Tlim) at constant load at V̇o2 max velocity in normoxia and muscular levels of selected mRNAs in biopsies were determined before and after training. V̇o2 max (+5%) and Tlim (+35%) increased specifically in the Hyp group. At the molecular level, mRNA concentrations of the hypoxia-inducible factor 1α (+104%), glucose transporter-4 (+32%), phosphofructokinase (+32%), peroxisome proliferator-activated receptor gamma coactivator 1α (+60%), citrate synthase (+28%), cytochrome oxidase 1 (+74%) and 4 (+36%), carbonic anhydrase-3 (+74%), and manganese superoxide dismutase (+44%) were significantly augmented in muscle after exercise training in Hyp only. Significant correlations were noted between muscular mRNA levels of monocarboxylate transporter-1, carbonic anhydrase-3, glucose transporter-4, and Tlim only in the group of athletes who trained in hypoxia ( P < 0.05). Accordingly, the addition of short hypoxic stress to the regular endurance training protocol induces transcriptional adaptations in skeletal muscle of athletic subjects. Expressional adaptations involving redox regulation and glucose uptake are being recognized as a potential molecular pathway, resulting in improved endurance performance in hypoxia-trained subjects.

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