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 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.

Effects of prior heavy-intensity exercise on pulmonary O2 uptake and muscle deoxygenation kinetics in young and older adult humans

2004 ◽  
Vol 97 (3) ◽  
pp. 998-1005 ◽  
Author(s):  
Darren S. DeLorey ◽  
John M. Kowalchuk ◽  
Donald H. Paterson
Keyword(s):  
Older Adults ◽  
Near Infrared ◽  
Vastus Lateralis ◽  
Muscle Blood Flow ◽  
Moderate Intensity ◽  
Vastus Lateralis Muscle ◽  
Warm Up ◽  
Muscle Deoxygenation ◽  
Older Subjects ◽  
Young Subjects

Pulmonary O2 uptake (V̇o2p) and muscle deoxygenation kinetics were examined during moderate-intensity cycling (80% lactate threshold) without warm-up and after heavy-intensity warm-up exercise in young ( n = 6; 25 ± 3 yr) and older ( n = 5; 68 ± 3 yr) adults. We hypothesized that heavy warm-up would speed V̇o2p kinetics in older adults consequent to an improved intramuscular oxygenation. Subjects performed step transitions ( n = 4; 6 min) from 20 W to moderate-intensity exercise preceded by either no warm-up or heavy-intensity warm-up (6 min). V̇o2p was measured breath by breath. Oxy-, deoxy-(HHb), and total hemoglobin and myoglobin (Hbtot) of the vastus lateralis muscle were measured continuously by near-infrared spectroscopy (NIRS). V̇o2p (phase 2; τ) and HHb data were fit with a monoexponential model. After heavy-intensity warm-up, oxyhemoglobin (older subjects: 13 ± 9 μM; young subjects: 9 ± 8 μM) and Hbtot (older subjects: 12 ± 8 μM; young subjects: 14 ± 10 μM) were elevated ( P < 0.05) relative to the no warm-up pretransition baseline. In older adults, τV̇o2p adapted at a faster rate ( P < 0.05) after heavy warm-up (30 ± 7 s) than no warm-up (38 ± 5 s), whereas in young subjects, τV̇o2p was similar in no warm-up (26 ± 7 s) and heavy warm-up (25 ± 5 s). HHb adapted at a similar rate in older and young adults after no warm-up; however, in older adults after heavy warm-up, the adaptation of HHb was slower ( P < 0.01) compared with young and no warm-up. These data suggest that, in older adults, V̇o2p kinetics may be limited by a slow adaptation of muscle blood flow and O2 delivery.

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.

Oxygen uptake kinetics for moderate exercise are speeded in older humans by prior heavy exercise

2002 ◽  
Vol 92 (2) ◽  
pp. 609-616 ◽  
Author(s):  
Barry W. Scheuermann ◽  
Chris Bell ◽  
Donald H. Paterson ◽  
Thomas J. Barstow ◽  
John M. Kowalchuk
Keyword(s):  
Older Adults ◽  
Young Adults ◽  
Muscle Blood Flow ◽  
Exponential Model ◽  
Work Rate ◽  
Moderate Intensity ◽  
Moderate Exercise ◽  
Heavy Exercise ◽  
Younger Adults ◽  
Warm Up

This study examined the effect of heavy-intensity warm-up exercise on O2 uptake (V˙o 2) kinetics at the onset of moderate-intensity (80% ventilation threshold), constant-work rate exercise in eight older (65 ± 2 yr) and seven younger adults (26 ± 1 yr). Step increases in work rate from loadless cycling to moderate exercise (Mod1), heavy exercise, and moderate exercise (Mod2) were performed. Each exercise bout was 6 min in duration and separated by 6 min of loadless cycling.V˙o 2 kinetics were modeled from the onset of exercise by use of a two-component exponential model. Heart rate (HR) kinetics were modeled from the onset of exercise using a single exponential model. During Mod1, the time constant (τ) for the predominant rise in V˙o 2(τV˙o 2) was slower ( P < 0.05) in the older adults (50 ± 10 s) than in young adults (19 ± 5 s). The older adults demonstrated a speeding ( P < 0.05) of V˙o 2kinetics when moderate-intensity exercise (Mod2) was preceded by high-intensity warm-up exercise (τV˙o 2, 27 ± 3 s), whereas young adults showed no speeding of V˙o 2kinetics (τV˙o 2, 17 ± 3 s). In the older and younger adults, baseline HR preceding Mod2was elevated compared with Mod1, but the τ for HR kinetics was slowed ( P < 0.05) in Mod2only for the older adults. Prior heavy-intensity exercise in old, but not young, adults speeded V˙o 2 kinetics during Mod2. Despite slowed HR kinetics in Mod2in the older adults, an elevated baseline HR before the onset of Mod2 may have led to sufficient muscle perfusion and O2 delivery. These results suggest that, when muscle blood flow and O2 delivery are adequate, muscle O2consumption in both old and young adults is limited by intracellular processes within the exercising muscle.

Effects of hyperventilation on phosphocreatine kinetics and muscle deoxygenation during moderate-intensity plantar flexion exercise

2007 ◽  
Vol 102 (4) ◽  
pp. 1565-1573 ◽  
Author(s):  
S. C. Forbes ◽  
J. M. Kowalchuk ◽  
R. T. Thompson ◽  
G. D. Marsh
Keyword(s):  
Near Infrared ◽  
Plantar Flexion ◽  
High Energy ◽  
Ion Concentration ◽  
Moderate Intensity ◽  
High Energy Phosphates ◽  
Moderate Intensity Exercise ◽  
Hydrogen Ion Concentration ◽  
Muscle Deoxygenation ◽  
Plantar Flexion Exercise

The effects of controlled voluntary hyperventilation (Hyp) on phosphocreatine (PCr) kinetics and muscle deoxygenation were examined during moderate-intensity plantar flexion exercise. Male subjects ( n = 7) performed trials consisting of 20-min rest, 6-min exercise, and 10-min recovery in control [Con; end-tidal Pco2 (PetCO2) ∼ 33 mmHg] and Hyp (PetCO2 ∼17 mmHg) conditions. Phosphorus-31 magnetic resonance and near-infrared spectroscopy were used simultaneously to monitor intramuscular acid-base status, high-energy phosphates, and muscle oxygenation. Resting intracellular hydrogen ion concentration ([H+]i) was lower ( P < 0.05) in Hyp [90 nM (SD 3)] than Con [96 nM (SD 4)]; however, at end exercise, [H+]i was greater ( P < 0.05) in Hyp [128 nM (SD 19)] than Con [120 nM (SD 17)]. At rest, [PCr] was not different between Con [36 mM (SD 2)] and Hyp [36 mM (SD 1)]. The time constant (τ) of PCr breakdown during transition from rest to exercise was greater ( P < 0.05) in Hyp [39 s (SD 22)] than Con [32 s (SD 22)], and the PCr amplitude was greater ( P < 0.05) in Hyp [26% (SD 4)] than Con [22% (SD 6)]. The deoxyhemoglobin and/or deoxymyoglobin (HHb) τ was similar between Hyp [13 s (SD 8)] and Con [10 s (SD 3)]; however, the amplitude was increased ( P < 0.05) in Hyp [40 arbitrary units (au) (SD 23)] compared with Con [26 au (SD 17)]. In conclusion, our results indicate that Hyp-induced hypocapnia enhanced substrate-level phosphorylation during moderate-intensity exercise. In addition, the increased amplitude of the HHb response suggests a reduced local muscle perfusion in Hyp compared with Con.

Effects of ageing on muscle O2 utilization and muscle oxygenation during the transition to moderate-intensity exercise

2007 ◽  
Vol 32 (6) ◽  
pp. 1251-1262 ◽  
Author(s):  
Darren S. DeLorey ◽  
Donald H. Paterson ◽  
John M. Kowalchuk
Keyword(s):  
Older Adults ◽  
Near Infrared ◽  
Oxidative Capacity ◽  
Delivery Systems ◽  
Enzyme Activation ◽  
Uptake Kinetics ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Age Related ◽  
Integrated Response

At the onset of exercise, an increase in muscle and pulmonary O2 consumption is met by increases in muscle O2 delivery and muscle O2 extraction. Thus, the study of pulmonary O2 uptake kinetics reflects the integrated response between the convective and diffusive O2 delivery systems and the muscle metabolic machinery (i.e., mitochondrial enzyme activation and provision of acetyl groups to the tricarboxcylic acid cycle) to increase muscle O2 consumption. Pulmonary O2 uptake kinetics are slowed in older adults compared with young adults and previous studies suggest that the slower O2 uptake kinetics may be the result of an age-associated decline in the ability of older adults to increase O2 delivery to active muscles. However, an inherent limitation to understanding the control of and limitations to pulmonary O2 uptake kinetics is that it is methodologically difficult to examine the adaptation of muscle perfusion and O2 delivery and muscle O2 utilization in the muscle microcirculation of active muscles in the dynamically exercising human. In this review, we provide an overview of the effect of ageing on pulmonary O2 uptake kinetics (reflecting the activation of muscle O2 consumption) during the transition to moderate-intensity exercise. Age-related changes in O2 delivery systems and muscle oxidative capacity are examined as potential limitations to pulmonary O2 uptake kinetics. We then review recent studies from our laboratory that have investigated the control of pulmonary O2 uptake kinetics at the level of the muscle microcirculation by examining the adaptation of muscle O2 delivery and muscle O2 utilization using near-infrared spectroscopy during the transition to exercise in healthy young and older adults.

Relationship between pulmonary O2 uptake kinetics and muscle deoxygenation during moderate-intensity exercise

2003 ◽  
Vol 95 (1) ◽  
pp. 113-120 ◽  
Author(s):  
Darren S. DeLorey ◽  
John M. Kowalchuk ◽  
Donald H. Paterson
Keyword(s):  
Near Infrared ◽  
Vastus Lateralis ◽  
Metabolic Activation ◽  
Moderate Intensity ◽  
Vastus Lateralis Muscle ◽  
Phase 2 ◽  
Moderate Intensity Exercise ◽  
Muscle Deoxygenation ◽  
Monoexponential Model ◽  
Kinetics Of

The temporal relationship between the kinetics of phase 2 pulmonary O2 uptake (V̇o2p) and deoxygenation of the vastus lateralis muscle was examined during moderate-intensity leg-cycling exercise. Young adults (5 men, 6 women; 23 ± 3 yr; mean ± SD) performed repeated transitions on 3 separate days from 20 W to a constant work rate corresponding to 80% of lactate threshold. Breath-by-breath V̇o2p was measured by mass spectrometer and volume turbine. Deoxyhemoglobin (HHb), oxyhemoglobin, and total hemoglobin and myoglobin were sampled each second by near-infrared spectroscopy (Hamamatsu NIRO-300). V̇o2p data were filtered, interpolated to 1 s, and averaged to 5-s bins; HHb data were averaged to 5-s bins. Phase 2 V̇o2p data were fit with a monoexponential model. For HHb, a time delay (TDHHb) from exercise onset to an increase in HHb was determined, and thereafter data were fit with a monoexponential model. The time constant for V̇o2p (30 ± 8 s) was slower ( P < 0.01) than that for HHb (10 ± 3 s). The TDHHb before an increase in HHb was 13 ± 2 s. The possible mechanisms of the TDHHb are discussed with reference to metabolic activation and matching of local muscle O2 delivery and O2 utilization. After this initial TDHHb, the kinetics of local muscle deoxygenation were faster than those of phase 2 V̇o2p (and presumably muscle O2 consumption), reflecting increased O2 extraction and a mismatch between local muscle O2 consumption and perfusion.

Regulation of V̇o2 kinetics by O2 delivery: insights from acute hypoxia and heavy-intensity priming exercise in young men

2012 ◽  
Vol 112 (6) ◽  
pp. 1023-1032 ◽  
Author(s):  
Matthew D. Spencer ◽  
Juan M. Murias ◽  
Tyler M. Grey ◽  
Donald H. Paterson
Keyword(s):  
Near Infrared ◽  
Acute Hypoxia ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Muscle Deoxygenation ◽  
V̇o2 Kinetics ◽  
Leg Cycling ◽  
Priming Exercise ◽  
The Individual ◽  
O2 Delivery

This study examined the separate and combined effects of acute hypoxia (Hypo) and heavy-intensity “priming” exercise (Hvy) on pulmonary O2 uptake (V̇o2p) kinetics during moderate-intensity exercise (Mod). Breath-by-breath V̇o2p and near-infrared spectroscopy-derived muscle deoxygenation {deoxyhemoglobin concentration [HHb]} were monitored continuously in 10 men (23 ± 4 yr) during repetitions of a Mod 1-Hvy-Mod 2 protocol, where each of the 6-min (Mod or Hvy) leg-cycling bouts was separated by 6 min at 20 W. Subjects were exposed to Hypo [fraction of inspired O2 (FiO2) = 15%, Mod 2 + Hypo] or “sham” (FiO2 = 20.9%, Mod 2-N) 2 min following Hvy in half of these repetitions; Mod was also performed in Hypo without Hvy (Mod 1 + Hypo). On-transient V̇o2p and [HHb] responses were modeled as a monoexponential. Data were scaled to a relative percentage of the response (0–100%), the signals were time-aligned, and the individual [HHb]-to-V̇o2 ratio was calculated. Compared with control (Mod 1), τV̇o2p and the O2 deficit (26 ± 7 s and 638 ± 144 ml, respectively) were reduced ( P < 0.05) in Mod 2-N (20 ± 5 s and 529 ± 196 ml) and increased ( P < 0.05) in Mod 1 + Hypo (34 ± 14 s and 783 ± 184 ml); in Mod 2 + Hypo, τV̇o2p was increased (30 ± 8 s, P < 0.05), yet O2 deficit was unaffected (643 ± 193 ml, P > 0.05). The modest “overshoot” in the [HHb]-to-V̇o2 ratio (reflecting an O2 delivery-to-utilization mismatch) in Mod 1 (1.06 ± 0.04) was abolished in Mod 2-N (1.00 ± 0.05), persisted in Mod 2 + Hypo (1.09 ± 0.07), and tended to increase in Mod 1 + Hypo (1.10 ± 0.09, P = 0.13). The present data do not support an “O2 delivery-independent” speeding of τV̇o2p following Hvy (or Hvy + Hypo); rather, this study suggests that local muscle O2 delivery likely governs the rate of adjustment of V̇o2 at τV̇o2p greater than ∼20 s.

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