Prior heavy-intensity exercise speeds V̇o2 kinetics during moderate-intensity exercise in young adults

2005 ◽  
Vol 98 (4) ◽  
pp. 1371-1378 ◽  
Author(s):  
Brendon J. Gurd ◽  
Barry W. Scheuermann ◽  
Donald H. Paterson ◽  
John M. Kowalchuk
Keyword(s):  
Young Adults ◽  
Lactate Threshold ◽  
Near Infrared ◽  
Linear Regression Analysis ◽  
Cycle Ergometer ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Warm Up ◽  
Total Hemoglobin ◽  
Concentration Changes

The effect of prior heavy-intensity warm-up exercise on subsequent moderate-intensity phase 2 pulmonary O2 uptake kinetics (τV̇o2) was examined in young adults exhibiting relatively fast (FK; τV̇o2 < 30 s; n = 6) and slow (SK; τV̇o2 > 30 s; n = 6) V̇o2 kinetics in moderate-intensity exercise without prior warm up. Subjects performed four repetitions of a moderate (Mod1)-heavy-moderate (Mod2) protocol on a cycle ergometer with work rates corresponding to 80% estimated lactate threshold (moderate intensity) and 50% difference between lactate threshold and peak V̇o2 (heavy intensity); each transition lasted 6 min, and each was preceded by 6 min of cycling at 20 W. V̇o2 and heart rate (HR) were measured breath-by-breath and beat-by-beat, respectively; concentration changes of muscle deoxyhemoglobin (HHb), oxyhemoglobin, and total hemoglobin were measured by near-infrared spectroscopy (Hamamatsu NIRO 300). τV̇o2 was lower ( P < 0.05) in Mod2 than in Mod1 in both FK (20 ± 5 s vs. 26 ± 5 s, respectively) and SK (30 ± 8 s vs. 45 ± 11 s, respectively); linear regression analysis showed a greater “speeding” of V̇o2 kinetics in subjects exhibiting a greater Mod1 τV̇o2. HR, oxyhemoglobin, and total hemoglobin were elevated ( P < 0.05) in Mod2 compared with Mod1. The delay before the increase in HHb was reduced ( P < 0.05) in Mod2, whereas the HHb mean response time was reduced ( P < 0.05) in FK (Mod2, 22 ± 3 s; Mod1, 32 ± 11 s) but not different in SK (Mod2, 36 ± 13 s; Mod1, 34 ± 15 s). We conclude that improved muscle perfusion in Mod2 may have contributed to the faster adaptation of V̇o2, especially in SK; however, a possible role for metabolic inertia in some subjects cannot be overlooked.

O2 uptake kinetics, pyruvate dehydrogenase activity, and muscle deoxygenation in young and older adults during the transition to moderate-intensity exercise

2008 ◽  
Vol 294 (2) ◽  
pp. R577-R584 ◽  
Author(s):  
B. J. Gurd ◽  
S. J. Peters ◽  
G. J. F. Heigenhauser ◽  
P. J. LeBlanc ◽  
T. J. Doherty ◽  
...  
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Pyruvate Dehydrogenase ◽  
Lactate Threshold ◽  
Time Course ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Similar Time ◽  
O2 Uptake Kinetics ◽  
The Relationship

The adaptation of pulmonary O2 uptake (V̇o2p) kinetics is slowed in older compared with young adults during the transition to moderate-intensity exercise. In this study, we examined the relationship between V̇o2p kinetics and mitochondrial pyruvate dehydrogenase (PDH) activity in young ( n = 7) and older ( n = 6) adults. Subjects performed cycle exercise to a work rate corresponding to ∼90% of estimated lactate threshold. Phase 2 V̇o2p kinetics were slower ( P < 0.05) in older (τ = 40 ± 17 s) compared with young (τ = 21 ± 6 s) adults. Relative phosphocreatine (PCr) breakdown was greater ( P < 0.05) at 30 s in older compared with young adults. Absolute PCr breakdown at 6 min was greater ( P < 0.05) in older compared with young adults. In young adults, PDH activity increased ( P < 0.05) from baseline to 30 s, with no further change observed at 6 min. In older adults, PDH activity during baseline exercise was similar to that seen in young adults. During the exercise transition, PDH activity did not increase ( P > 0.05) at 30 s of exercise but was elevated ( P < 0.05) after 6 min. The change in deoxyhemoglobin (HHb) was greater for a given V̇o2p in older adults, and there was a similar time course of HHb accompanying the slower V̇o2p kinetics in the older adults, suggesting a slower adaptation of bulk O2 delivery in older adults. In conclusion, the slower adaptation of V̇o2p in older adults is likely a result of both an increased metabolic inertia and lower O2 availability.

scholarly journals Adjustments of pulmonary O2 uptake and muscle deoxygenation during ramp incremental exercise and constant-load moderate-intensity exercise in young and older adults

2012 ◽  
Vol 113 (9) ◽  
pp. 1466-1475 ◽  
Author(s):  
Braden M. R. Gravelle ◽  
Juan M. Murias ◽  
Matthew D. Spencer ◽  
Donald H. Paterson ◽  
John M. Kowalchuk
Keyword(s):  
Older Adults ◽  
Lactate Threshold ◽  
Near Infrared ◽  
Vastus Lateralis ◽  
Constant Load ◽  
Moderate Intensity ◽  
Sigmoid Function ◽  
Moderate Intensity Exercise ◽  
Muscle Deoxygenation ◽  
Age Related

The matching of muscle O2 delivery to O2 utilization can be inferred from the adjustments in muscle deoxygenation (Δ[HHb]) and pulmonary O2 uptake (V̇o2p). This study examined the adjustments of V̇o2p and Δ[HHb] during ramp incremental (RI) and constant-load (CL) exercise in adult males. Ten young adults (YA; age: 25 ± 5 yr) and nine older adults (OA; age: 70 ± 3 yr) completed two RI tests and six CL step transitions to a work rate (WR) corresponding to 1) 80% of the estimated lactate threshold (same relative WR) and 2) 50 W (same absolute WR). V̇o2p was measured breath by breath, and Δ[HHb] of the vastus lateralis was measured using near-infrared spectroscopy. Δ[HHb]-WR profiles were normalized from baseline (0%) to peak Δ[HHb] (100%) and fit using a sigmoid function. The sigmoid slope ( d) was greater ( P < 0.05) in OA (0.027 ± 0.01%/W) compared with YA (0.017 ± 0.01%/W), and the c/ d value (a value corresponding to 50% of the amplitude) was smaller ( P < 0.05) for OA (133 ± 40 W) than for YA (195 ± 51 W). No age-related differences in the sigmoid parameters were reported when WR was expressed as a percentage of peak WR. V̇o2p kinetics compared with Δ[HHb] kinetics for the 50-W transition were similar between YA and OA; however, Δ[HHb] kinetics during the transition to 80% of the lactate threshold were faster than V̇o2p kinetics in both groups. The greater reliance on O2 extraction displayed in OA during RI exercise suggests a lower O2 delivery-to-O2 utilization relationship at a given absolute WR compared with YA.

scholarly journals Pulmonary O2 uptake and leg blood flow kinetics during moderate exercise are slowed by hyperventilation-induced hypocapnic alkalosis

2010 ◽  
Vol 108 (6) ◽  
pp. 1641-1650 ◽  
Author(s):  
Lisa M. K. Chin ◽  
George J. F. Heigenhauser ◽  
Donald H. Paterson ◽  
John M. Kowalchuk
Keyword(s):  
Blood Flow ◽  
Femoral Artery ◽  
Near Infrared ◽  
Vastus Lateralis ◽  
Microvascular Blood Flow ◽  
Moderate Intensity ◽  
Vastus Lateralis Muscle ◽  
Moderate Intensity Exercise ◽  
Concentration Changes ◽  
Hypocapnic Alkalosis

The effect of hyperventilation-induced hypocapnic alkalosis (Hypo) on the adjustment of pulmonary O2 uptake (V̇o2p) and leg femoral conduit artery (“bulk”) blood flow (LBF) during moderate-intensity exercise (Mod) was examined in eight young male adults. Subjects completed four to six repetitions of alternate-leg knee-extension exercise during normal breathing [Con; end-tidal partial pressure of CO2 (PetCO2) ∼40 mmHg] and sustained hyperventilation (Hypo; PetCO2 ∼20 mmHg). Increases in work rate were made instantaneously from baseline (3 W) to Mod (80% estimated lactate threshold). V̇o2p was measured breath by breath by mass spectrometry and volume turbine, and LBF (calculated from mean femoral artery blood velocity and femoral artery diameter) was measured simultaneously by Doppler ultrasound. Concentration changes of deoxy (Δ[HHb])-, oxy (Δ[O2Hb])-, and total hemoglobin-myoglobin (Δ[HbTot]) of the vastus lateralis muscle were measured continuously by near-infrared spectroscopy (NIRS). The kinetics of V̇o2p, LBF, and Δ[HHb] were modeled using a monoexponential equation by nonlinear regression. The time constants for the phase 2 V̇o2p (Hypo, 49 ± 26 s; Con, 28 ± 8 s) and LBF (Hypo, 46 ± 16 s; Con, 23 ± 6 s) were greater ( P < 0.05) in Hypo compared with Con. However, the mean response time for the overall Δ[HHb] response was not different between conditions (Hypo, 23 ± 5 s; Con, 24 ± 3 s), whereas the Δ[HHb] amplitude was greater ( P < 0.05) in Hypo (8.05 ± 7.47 a.u.) compared with Con (6.69 ± 6.31 a.u.). Combined, these results suggest that hyperventilation-induced hypocapnic alkalosis is associated with slower convective (i.e., slowed femoral artery and microvascular blood flow) and diffusive (i.e., greater fractional O2 extraction for a given ΔV̇o2p) O2 delivery, which may contribute to the hyperventilation-induced slowing of V̇o2p (and muscle O2 utilization) kinetics.

Prior heavy exercise elevates pyruvate dehydrogenase activity and muscle oxygenation and speeds O2 uptake kinetics during moderate exercise in older adults

2009 ◽  
Vol 297 (3) ◽  
pp. R877-R884 ◽  
Author(s):  
Brendon J. Gurd ◽  
Sandra J. Peters ◽  
George J. F. Heigenhauser ◽  
Paul J. LeBlanc ◽  
Timothy J. Doherty ◽  
...  
Keyword(s):  
Older Adults ◽  
Pyruvate Dehydrogenase ◽  
Near Infrared ◽  
Muscle Oxygenation ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Younger Adults ◽  
Warm Up ◽  
Muscle Deoxygenation ◽  
Exercise Activity

The adaptation of pulmonary oxygen uptake (V̇o2p) kinetics during the transition to moderate-intensity exercise is slowed in older compared with younger adults; however, this response is faster following a prior bout of heavy-intensity exercise. We have examined V̇o2p kinetics, pyruvate dehydrogenase (PDH) activation, muscle metabolite contents, and muscle deoxygenation in older adults [ n = 6; 70 ± 5 (67–74) yr] during moderate-intensity exercise (Mod1) and during moderate-intensity exercise preceded by heavy-intensity warm-up exercise (Mod2). The phase 2 V̇o2p time constant (τV̇o2p) was reduced ( P < 0.05) in Mod2 (29 ± 5 s) compared with Mod1 (39 ± 14 s). PDH activity was elevated ( P < 0.05) at baseline prior to Mod2 (2.1 ± 0.6 vs. 1.2 ± 0.3 mmol acetyl-CoA·min−1·kg wet wt−1), and the delay in attaining end-exercise activity was abolished. Phosphocreatine breakdown during exercise was reduced ( P < 0.05) at both 30 s and 6 min in Mod2 compared with Mod1. Near-infrared spectroscopy-derived indices of muscle oxygenation were elevated both prior to and throughout Mod2, while muscle deoxygenation kinetics were not different between exercise bouts consistent with elevated perfusion and O2 availability. These results suggest that in older adults, faster V̇o2p kinetics following prior heavy-intensity exercise are likely a result of prior activation of mitochondrial enzyme activity in combination with elevated muscle perfusion and O2 availability.

scholarly journals Frontal and motor cortex oxygenation during maximal exercise in normoxia and hypoxia

2009 ◽  
Vol 106 (4) ◽  
pp. 1153-1158 ◽  
Author(s):  
Andrew W. Subudhi ◽  
Brittany R. Miramon ◽  
Matthew E. Granger ◽  
Robert C. Roach
Keyword(s):  
Motor Cortex ◽  
Near Infrared ◽  
Maximal Exercise ◽  
Acute Hypoxia ◽  
Moderate Intensity ◽  
Chamber Pressure ◽  
Motor Drive ◽  
Maximal Power ◽  
Moderate Intensity Exercise ◽  
Test Order

Reductions in prefrontal oxygenation near maximal exertion may limit exercise performance by impairing executive functions that influence the decision to stop exercising; however, whether deoxygenation also occurs in motor regions that more directly affect central motor drive is unknown. Multichannel near-infrared spectroscopy was used to compare changes in prefrontal, premotor, and motor cortices during exhaustive exercise. Twenty-three subjects performed two sequential, incremental cycle tests (25 W/min ramp) during acute hypoxia [79 Torr inspired Po2 (PiO2)] and normoxia (117 Torr PiO2) in an environmental chamber. Test order was balanced, and subjects were blinded to chamber pressure. In normoxia, bilateral prefrontal oxygenation was maintained during low- and moderate-intensity exercise but dropped 9.0 ± 10.7% (mean ± SD, P < 0.05) before exhaustion (maximal power = 305 ± 52 W). The pattern and magnitude of deoxygenation were similar in prefrontal, premotor, and motor regions ( R2 > 0.94). In hypoxia, prefrontal oxygenation was reduced 11.1 ± 14.3% at rest ( P < 0.01) and fell another 26.5 ± 19.5% ( P < 0.01) at exhaustion (maximal power = 256 ± 38 W, P < 0.01). Correlations between regions were high ( R2 > 0.61), but deoxygenation was greater in prefrontal than premotor and motor regions ( P < 0.05). Prefrontal, premotor, and motor cortex deoxygenation during high-intensity exercise may contribute to an integrative decision to stop exercise. The accelerated rate of cortical deoxygenation in hypoxia may hasten this effect.

Fat and carbohydrate metabolism during exercise in elderly and young subjects

1996 ◽  
Vol 271 (6) ◽  
pp. E983-E989 ◽  
Author(s):  
S. Sial ◽  
A. R. Coggan ◽  
R. Carroll ◽  
J. Goodwin ◽  
S. Klein
Keyword(s):  
Young Adults ◽  
Carbohydrate Metabolism ◽  
Relative Intensity ◽  
The Elderly ◽  
Absolute Intensity ◽  
Substrate Oxidation ◽  
Carbohydrate Oxidation ◽  
Moderate Intensity ◽  
Elderly Subjects ◽  
Moderate Intensity Exercise

We evaluated the effect of aging on fat and carbohydrate metabolism during moderate intensity exercise. Glycerol, free fatty acid (FFA), and glucose rate of appearance (Ra) in plasma and substrate oxidation were determined during 60 min of cycle ergometer exercise in six elderly (73 +/- 2 yr) and six young adults (26 +/- 2 yr) matched by gender and lean body mass. The elderly group was studied during exercise performed at 56 +/- 3% of maximum oxygen uptake, whereas the young adults were studied during exercise performed at the same absolute and at a similar relative intensity as the elderly subjects. Mean fat oxidation during exercise was 25-35% lower in the elderly subjects than in the young adults exercising at either the same absolute or similar relative intensities (P < 0.05). Mean carbohydrate oxidation in the elderly group was 35% higher than the young adults exercising at the same absolute intensity (P < 0.001) but 40% lower than the young adults exercising at the same relative intensity (P < 0.001). Average FFA Ra in the elderly subjects was 85% higher than in the young adults exercising at the same absolute intensity (P < 0.05) but 35% lower than the young adults exercising at a similar relative intensity (P < 0.05). We conclude that fat oxidation is decreased while carbohydrate oxidation is increased during moderate intensity exercise in elderly men and women. The shift in substrate oxidation was caused by age-related changes in skeletal muscle respiratory capacity because lipolytic rates and FFA availability were not rate limiting in the older subjects.

scholarly journals The Regulation of the Metastatic Cascade by Physical Activity: A Narrative Review

Cancers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 153 ◽  
Author(s):  
Sophie van Doorslaer de ten Ryen ◽  
Louise Deldicque
Keyword(s):  
Physical Activity ◽  
Careful Analysis ◽  
The Body ◽  
Narrative Review ◽  
Moderate Intensity ◽  
Moderate Physical Activity ◽  
Moderate Intensity Exercise ◽  
Tumor Spread ◽  
Warm Up ◽  
Cancer Dissemination

The purpose of this narrative review is to provide an overview of the currently available knowledge about the mechanisms by which physical activity may affect metastatic development. The search terms exercise [Title/Abstract] AND metastasis [Title/Abstract] returned 222 articles on PUBMED on the 10 February 2019. After careful analysis of the abstracts, a final selection of 24 articles was made. Physical activity regulates the levels of metastatic factors in each of the five steps of the process. Moderate intensity exercise appears to prevent tumor spread around the body, among others, by normalizing angiogenesis, destroying circulating tumor cells, and decreasing endothelial cells permeability. Contrarily, high-intensity exercise seems to favor cancer dissemination, likely through excessive stress, which can be somewhat counteracted by an appropriate warm-up. In conclusion, chronic adaptations to moderate-intensity endurance exercise seem the most effective way to achieve a preventive effect of exercise on metastases. Altogether, the data gathered here reinforce the importance of encouraging cancer patients to perform moderate physical activity several times a week. To limit the undesired events thereof, a good knowledge of the patient’s training level is important to establish an adapted exercise training program.

scholarly journals Moderate intensity exercise in hypoxia increases IGF-1 bioavailability and serum irisin in individuals with type 1 diabetes

2020 ◽  
Vol 11 ◽  
pp. 204201882092532 ◽  
Author(s):  
Aleksandra Żebrowska ◽  
Marcin Sikora ◽  
Anna Konarska ◽  
Anna Zwierzchowska ◽  
Tomasz Kamiński ◽  
...  
Keyword(s):  
Type 1 Diabetes ◽  
Serum Levels ◽  
Cycle Ergometer ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Physiological Variables ◽  
Hypoxic Conditions ◽  
Study Results ◽  
Glycaemia Control

Aim: This study aimed to determine the effect of moderate intensity continuous exercise (Ex) and hypoxia (Hyp) on serum brain-derived neurotrophic factor (BDNF), insulin-like growth factor-1 (IGF-1) and its binding protein-3 (IGFBP-3), irisin and cytokines levels in patients with type 1 diabetes (T1D). Methods: A total of 14 individuals with T1D (age: 28.7 ± 7.3 years) and 14 healthy adults (age: 27.1 ± 3.9 years) performed 40-min continuous Ex at moderate intensity (50% lactate threshold) on a cycle ergometer in normoxia (Nor) and Hyp (FiO2 = 15.1%) Biochemical factors, glucose concentrations and physiological variables were measured at rest, immediately and up to 24 h after both Ex protocols. Results: Patients with T1D had significantly lower pre-Ex serum concentrations of BDNF ( p < 0.05, p < 0.01), and total IGF-1 ( p < 0.001, p < 0.05) and significantly higher irisin levels ( p < 0.05, p < 0.01) in Nor and Hyp, compared with healthy subjects. Ex significantly increased in T1D group serum BDNF (in Nor only p < 0.05) and total IGF-1 levels in Nor and Hyp ( p < 0.001 and p < 0.01, respectively). Immediately after Ex in Hyp, freeIGF-1 ( p < 0.05) and irisin levels ( p < 0.001) were significantly higher compared with the levels induced by Ex alone. Free IGF-1 and irisin serum levels remained elevated in 24 h post-Ex in Hyp. In T1D, significant blood glucose (BG) decrease was observed immediately after Ex in Hyp ( p < 0.001) and in 24 h recovery ( p < 0.001) compared with pre-Ex level. Conclusion: The study results suggest that moderate intensity continuous Ex has beneficial effect on BDNF and IGF-1 levels. Ex in hypoxic conditions may be more effective in increasing availability of IGF-1. The alterations in the post-Ex irisin levels and IGF-1 system may be contributing to more effective glycaemia control in patients with T1D.

Peripheral Chemoreflex Drive in Moderate-Intensity Exercise

1996 ◽  
Vol 21 (4) ◽  
pp. 285-300 ◽  
Author(s):  
Claudette M. St. Croix ◽  
David A. Cunningham ◽  
Donald H. Paterson ◽  
John M. Kowalchuk
Keyword(s):  
Peak Level ◽  
Cycle Ergometer ◽  
Open Loop ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Peripheral Chemoreceptor ◽  
Carotid Bodies ◽  
Ergometer Exercise ◽  
End Tidal ◽  
Peripheral Chemoreflex

The purpose of this study was to measure the contribution of the peripheral chemoreceptor (pRc) to [Formula: see text] during the steady-state of moderate-intensity cycle ergometer exercise using continuous hyperoxic suppression of pRc drive, while stabilizing the drive from the central chemoreceptor by clamping end-tidal PCO2 (PETCO2) at the peak level attained during the hyperoxic period of a poikilocapnic ride. In the isocapnic protocol, the PETCO2 was maintained at a constant level by a negative feedback, open loop system. Five subjects completed four repetitions of each of the poikilocapnic and isocapnic protocols. In the poikilocapnic protocol, [Formula: see text] declined following the step into hyperoxia and then began to increase, whereas the decline in [Formula: see text] was maintained in the isocapnic protocol. However, the mean decrease in [Formula: see text] was not significantly different between the poikilocapnic (16.1 ± 5.0%) and isocapnic (14.9 ± 4.4%) protocols. These results suggest that the declining phase of [Formula: see text] is fully complete before the secondary central stimulating actions of hyperoxia on [Formula: see text] and that the pRc contributes about 15% of the drive to breathe in moderate intensity exercise. Key words: ventilatory control, carotid bodies, hyperoxia

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