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.

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.

scholarly journals Similar pattern of change in V̇o2 kinetics, vascular function, and tissue oxygen provision following an endurance training stimulus in older and young adults

2017 ◽  
Vol 312 (4) ◽  
pp. R467-R476 ◽  
Author(s):  
Kaitlin M. McLay ◽  
Juan M. Murias ◽  
Donald H. Paterson
Keyword(s):  
Exercise Training ◽  
Vascular Function ◽  
Time Course ◽  
Near Infrared ◽  
Training Stimulus ◽  
Hemoglobin Concentration ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Similar Time ◽  
Endurance Cycling

The purpose of this study was to examine the time course of changes in the oxygen uptake (V̇o2) kinetics response subsequent to short-term exercise training (i.e., 24, 48, 72, and 120 h posttraining) and examine the relationship with the time course of changes in microvascular [deoxygenated hemoglobin concentration ([HHb])-to-V̇o2 ratio ([HHb])/V̇o2)] and macrovascular [flow-mediated dilation (FMD)] O2 delivery to the active tissues/limbs. Seven healthy older [OA; 74 ± 6 (SD) yr] and young men (YA; 25 ± 3 yr) completed three endurance cycling exercise training sessions at 70% V̇o2peak. Moderate-intensity exercise on-transient V̇o2 (measured breath by breath) and [HHb] (measured by near-infrared spectroscopy) were modeled with a monoexponential and normalized (0–100% of response), and the [HHb])/V̇o2 was calculated. Ultrasound-derived FMD of the popliteal artery was assessed after 5 min of cuff occlusion. %FMD was calculated as the greatest percent change in diameter from baseline. Time constant of V̇o2 (τV̇o2) was significantly reduced in both OA (~18%) and YA (~23%) at 24 h ( P < 0.001) posttraining and remained decreased at 48 h before returning toward pretraining (PRE) values. Both groups showed a significant decrease in the [HHb])/V̇o2 at 24, 48, and 72 h ( P = 0.001, 0.01, and 0.03, respectively) posttraining before returning toward PRE values at 120 h. %FMD followed a similar time course to that of changes in the [HHb])/V̇o2, being significantly greater in both OA (by ~64%) and YA (by ~26%) at 24 h ( P < 0.001), remaining increased at 48 and 72 h ( P = 0.02 and 0.03, respectively), and returning toward PRE values at 120 h. These data suggest the rate of adjustment of V̇o2 may be constrained by O2 availability in the active tissues.

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.

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.

Effects of priming exercise on the speed of adjustment of muscle oxidative metabolism at the onset of moderate-intensity step transitions in older adults

2012 ◽  
Vol 302 (10) ◽  
pp. R1158-R1166 ◽  
Author(s):  
Gabriela De Roia ◽  
Silvia Pogliaghi ◽  
Alessandra Adami ◽  
Christina Papadopoulou ◽  
Carlo Capelli
Keyword(s):  
Older Adults ◽  
Cardiac Output ◽  
Oxidative Metabolism ◽  
Functional Decline ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Healthy Older Adults ◽  
Speed Of Adjustment ◽  
Priming Exercise ◽  
Kinetics Of

Aging is associated with a functional decline of the oxidative metabolism due to progressive limitations of both O2 delivery and utilization. Priming exercise (PE) increases the speed of adjustment of oxidative metabolism during successive moderate-intensity transitions. We tested the hypothesis that such improvement is due to a better matching of O2 delivery to utilization within the working muscles. In 21 healthy older adults (65.7 ± 5 yr), we measured contemporaneously noninvasive indexes of the overall speed of adjustment of the oxidative metabolism (i.e., pulmonary V̇o2 kinetics), of the bulk O2 delivery (i.e., cardiac output), and of the rate of muscle deoxygenation (i.e., deoxygenated hemoglobin, HHb) during moderate-intensity step transitions, either with (ModB) or without (ModA) prior PE. The local matching of O2 delivery to utilization was evaluated by the ΔHHb/ΔV̇o2 ratio index. The overall speed of adjustment of the V̇o2 kinetics was significantly increased in ModB compared with ModA ( P < 0.05). On the contrary, the kinetics of cardiac output was unaffected by PE. At the muscle level, ModB was associated with a significant reduction of the “overshoot” in the ΔHHb/ΔV̇o2 ratio compared with ModA ( P < 0.05), suggesting an improved O2 delivery. Our data are compatible with the hypothesis that, in older adults, PE, prior to moderate-intensity exercise, beneficially affects the speed of adjustment of oxidative metabolism due to an acute improvement of the local matching of O2 delivery to utilization.

The acute effects of differential dietary fatty acids on human skeletal muscle pyruvate dehydrogenase activity

2008 ◽  
Vol 104 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Nicolette S. Bradley ◽  
George J. F. Heigenhauser ◽  
Brian D. Roy ◽  
Elizabeth M. Staples ◽  
J. Greig Inglis ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Pyruvate Dehydrogenase ◽  
Dietary Fatty Acids ◽  
Metabolic Effects ◽  
Moderate Intensity ◽  
Acute Effects ◽  
Moderate Intensity Exercise ◽  
Important Regulator ◽  
Male Subjects ◽  
Muscle Biopsies

Pyruvate dehydrogenase (PDH) is an important regulator of carbohydrate oxidation during exercise, and its activity can be downregulated by an increase in dietary fat. The purpose of this study was to determine the acute metabolic effects of differential dietary fatty acids on the activation of the PDH complex (PDHa activity) at rest and at the onset of moderate-intensity exercise. University-aged male subjects ( n = 7) underwent two fat-loading trials spaced at least 2 wk apart. Subjects consumed ∼300 g saturated (SFA) or n-6 polyunsaturated fatty acid (PUFA) fat over the course of 5 h. Following this, participants cycled at 65% of their maximum oxygen uptake for 15 min. Muscle biopsies were taken before and following fat loading and at 1 min exercise. Plasma free fatty acids increased from 0.15 ± 0.07 to 0.54 ± 0.19 mM over 5 h with SFA and from 0.11 ± 0.04 to 0.35 ± 0.13 mM with n-6 PUFA and were significantly lower throughout the n-6 PUFA trial. PDHa activity was unchanged following fat loading but increased at the onset of exercise in the SFA trial, from 1.18 ± 0.27 to 2.16 ± 0.37 mmol·min−1·kg wet wt−1. This effect was negated in the n-6 PUFA trial (1.04 ± 0.20 to 1.28 ± 0.36 mmol·min−1·kg wet wt−1). PDH kinase was unchanged in both trials, suggesting that the attenuation of PDHa activity with n-6 PUFA was a result of changes in the concentrations of intramitochondrial effectors, potentially intramitochondrial NADH or Ca2+. Our findings suggest that attenuated PDHa activity contributes to the preferential oxidation of n-6 PUFA during moderate-intensity exercise.

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.

Processing gender stereotypes in dementia patients and older healthy adults: a self-paced reading study

2019 ◽  
Vol 5 (s2) ◽  
Author(s):  
Daniel Müller-Feldmeth ◽  
Katharina Ahnefeld ◽  
Adriana Hanulíková
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Sentence Processing ◽  
Gender Stereotypes ◽  
Time Course ◽  
Healthy Adults ◽  
Control Group ◽  
Healthy Older Adults ◽  
Dementia Patients ◽  
Age Related

AbstractWe used self-paced reading to examine whether stereotypical associations of verbs with women or men as prototypical agents (e.g. the craftsman knits a sweater) are activated during sentence processing in dementia patients and healthy older adults. Effects of stereotypical knowledge on language processing have frequently been observed in young adults, but little is known about age-related changes in the activation and integration of stereotypical information. While syntactic processing may remain intact, semantic capacities are often affected in dementia. Since inferences based on gender stereotypes draw on social and world knowledge, access to stereotype information may also be affected in dementia patients. Results from dementia patients (n = 9, average age 86.6) and healthy older adults (n = 14, average age 79.5) showed slower reading times and less accuracy in comprehension scores for dementia patients compared to the control group. While activation of stereotypical associations of verbs was visible in both groups, they differed with respect to the time-course of processing. The effect of stereotypes on comprehension accuracy was visible for healthy adults only. The evidence from reading times suggests that older adults with and without dementia engage stereotypical inferences during reading, which is in line with research on young adults.

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