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John M. Kowalchuk - One of the best experts on this subject based on the ideXlab platform.
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Speeding of VO2 kinetics during Moderate-Intensity Exercise subsequent to heavy-intensity Exercise is associated with improved local O2 distribution.
Journal of Applied Physiology, 2011Co-Authors: Juan M. Murias, Matthew D. Spencer, Darren S. Delorey, Brendon J. Gurd, John M. Kowalchuk, Donald H. PatersonAbstract:The relationship between the adjustment of muscle deoxygenation (Δ[HHb]) and phase II VO2p during Moderate-Intensity Exercise was examined before (Mod 1) and after (Mod 2) a bout of heavy-intensity...
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o2 uptake kinetics pyruvate dehydrogenase activity and muscle deoxygenation in young and older adults during the transition to moderate intensity Exercise
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2008Co-Authors: Brendon J. Gurd, Donald H. Paterson, George J F Heigenhauser, Sandra J Peters, Paul J Leblanc, Timothy J Doherty, John M. KowalchukAbstract:The adaptation of pulmonary O2 uptake (Vo2p) kinetics is slowed in older compared with young adults during the transition to Moderate-Intensity Exercise. In this study, we examined the relationship between Vo2p 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 Vo2p kinetics were slower ( 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 Vo2p in older adults, and there was a similar time course of HHb accompanying the slower Vo2p kinetics in the older adults, suggesting a slower adaptation of bulk O2 delivery in older adults. In conclusion, the slower adaptation of Vo2p in older adults is likely a result of both an increased metabolic inertia and lower O2 availability.
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hyperventilation induced hypocapnic alkalosis slows the adaptation of pulmonary o2 uptake during the transition to moderate intensity Exercise
The Journal of Physiology, 2007Co-Authors: Lisa M K Chin, John M. Kowalchuk, Donald H. Paterson, Ryan J Leigh, George J F Heigenhauser, Harry B RossiterAbstract:The effect of voluntary hyperventilation-induced hypocapnic alkalosis (RALK) on pulmonary O2 uptake () kinetics and muscle deoxygenation was examined in young male adults (n= 8) during Moderate-Intensity Exercise. Subjects performed five repetitions of a step-transition in work rate from 20 W cycling to a work rate corresponding to 90% of the estimated lactate threshold during control (CON; , ∼40 mmHg) and during hyperventilation (RALK; , ∼20 mmHg). was measured breath-by-breath and relative concentration changes in muscle deoxy- (ΔHHb), oxy- (ΔO2Hb) and total (ΔHbtot) haemoglobin were measured continuously using near-infrared (NIR) spectroscopy (Hamamatsu, NIRO 300). The time constant for the fundamental, phase 2, response (τ) was greater (P < 0.05) in RALK (48 ± 11 s) than CON (31 ± 9 s), while τHHb was similar between conditions (RALK, 12 ± 4 s; CON, 11 ± 4 s). The ΔHbtot was lower (P < 0.05) in RALK than CON, prior to (RALK, −3 ± 5 μmol l−1; CON, −1 ± 4 μmol l−1) and at the end (RALK, 1 ± 6 μmol l−1; CON, 5 ± 5 μmol l−1) of Moderate-Intensity Exercise. Although slower adaptation of during RALK may be related to an attenuated activation of PDH (and other enzymes) and provision of oxidizable substrate to the mitochondria (i.e. metabolic inertia), the present findings also suggest a role for a reduction in local muscle perfusion and O2 delivery.
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Hyperventilation‐induced hypocapnic alkalosis slows the adaptation of pulmonary O2 uptake during the transition to moderate‐intensity Exercise
The Journal of Physiology, 2007Co-Authors: Lisa M K Chin, Donald H. Paterson, Ryan J Leigh, George J F Heigenhauser, Harry B Rossiter, John M. KowalchukAbstract:The effect of voluntary hyperventilation-induced hypocapnic alkalosis (RALK) on pulmonary O2 uptake () kinetics and muscle deoxygenation was examined in young male adults (n= 8) during Moderate-Intensity Exercise. Subjects performed five repetitions of a step-transition in work rate from 20 W cycling to a work rate corresponding to 90% of the estimated lactate threshold during control (CON; , ∼40 mmHg) and during hyperventilation (RALK; , ∼20 mmHg). was measured breath-by-breath and relative concentration changes in muscle deoxy- (ΔHHb), oxy- (ΔO2Hb) and total (ΔHbtot) haemoglobin were measured continuously using near-infrared (NIR) spectroscopy (Hamamatsu, NIRO 300). The time constant for the fundamental, phase 2, response (τ) was greater (P < 0.05) in RALK (48 ± 11 s) than CON (31 ± 9 s), while τHHb was similar between conditions (RALK, 12 ± 4 s; CON, 11 ± 4 s). The ΔHbtot was lower (P < 0.05) in RALK than CON, prior to (RALK, −3 ± 5 μmol l−1; CON, −1 ± 4 μmol l−1) and at the end (RALK, 1 ± 6 μmol l−1; CON, 5 ± 5 μmol l−1) of Moderate-Intensity Exercise. Although slower adaptation of during RALK may be related to an attenuated activation of PDH (and other enzymes) and provision of oxidizable substrate to the mitochondria (i.e. metabolic inertia), the present findings also suggest a role for a reduction in local muscle perfusion and O2 delivery.
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o2 uptake and muscle deoxygenation kinetics during the transition to moderate intensity Exercise in different phases of the menstrual cycle in young adult females
European Journal of Applied Physiology, 2007Co-Authors: B J Gurd, Donald H. Paterson, J Scheid, John M. KowalchukAbstract:O2 uptake \((\dot{V}O_{2})\) kinetics were examined during the follicular (F) and luteal (L) phases of the menstrual cycle to determine if there was an effect of altered sex hormones on the \(\dot{V}O_{2}\) response to Moderate-Intensity Exercise. Seven healthy women (age 21 ± 2 years; mean ± SD) performed six transitions from 20 W to Moderate-Intensity Exercise (∼ 90 % \(\hat{\theta}_{{{\rm L}}}\)) during the F and L phase. \(\dot{V}O_{2}\) was measured breath-by-breath and deoxyhemoglobin/myoglobin (Δ HHb) was determined by near infrared spectroscopy. Progesterone and estrogen were significantly (P < 0.05) elevated during the L compared to F phase. \(\dot{V}O_{2}\) kinetics \((\tau \dot{V}O_{2})\) were not different in the two phases of the menstrual cycle (F, 22 ± 5 s; L, 22 ± 6 s; 95% confidence intervals ±4 s) nor was the time course of the Δ HHb response (F, TD 11 ± 2 s, τ 11 ± 3 s; L, TD 12 ± 2 s, τ 12 ± 11 s; τHHb 95% confidence intervals ±3 s). Respiratory exchange ratio (RER) was not different between phases for baseline or steady-state Exercise and the blood lactate response to Exercise was not different. In conclusion, \(\dot{V}O_{2}\) kinetics at the onset of Moderate-Intensity Exercise are not affected by the phase of the menstrual cycle in young females suggesting either no change in, or no effect of metabolic activation on the on-transient kinetics of Moderate-Intensity Exercise. Additionally, the similar adaptation of Δ HHb in combination with unchanged \(\dot{V}O_{2}\) suggests that there were no differences in the adaptation of local muscle O2 delivery.
Donald H. Paterson - One of the best experts on this subject based on the ideXlab platform.
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Speeding of VO2 kinetics during Moderate-Intensity Exercise subsequent to heavy-intensity Exercise is associated with improved local O2 distribution.
Journal of Applied Physiology, 2011Co-Authors: Juan M. Murias, Matthew D. Spencer, Darren S. Delorey, Brendon J. Gurd, John M. Kowalchuk, Donald H. PatersonAbstract:The relationship between the adjustment of muscle deoxygenation (Δ[HHb]) and phase II VO2p during Moderate-Intensity Exercise was examined before (Mod 1) and after (Mod 2) a bout of heavy-intensity...
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o2 uptake kinetics pyruvate dehydrogenase activity and muscle deoxygenation in young and older adults during the transition to moderate intensity Exercise
American Journal of Physiology-regulatory Integrative and Comparative Physiology, 2008Co-Authors: Brendon J. Gurd, Donald H. Paterson, George J F Heigenhauser, Sandra J Peters, Paul J Leblanc, Timothy J Doherty, John M. KowalchukAbstract:The adaptation of pulmonary O2 uptake (Vo2p) kinetics is slowed in older compared with young adults during the transition to Moderate-Intensity Exercise. In this study, we examined the relationship between Vo2p 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 Vo2p kinetics were slower ( 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 Vo2p in older adults, and there was a similar time course of HHb accompanying the slower Vo2p kinetics in the older adults, suggesting a slower adaptation of bulk O2 delivery in older adults. In conclusion, the slower adaptation of Vo2p in older adults is likely a result of both an increased metabolic inertia and lower O2 availability.
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hyperventilation induced hypocapnic alkalosis slows the adaptation of pulmonary o2 uptake during the transition to moderate intensity Exercise
The Journal of Physiology, 2007Co-Authors: Lisa M K Chin, John M. Kowalchuk, Donald H. Paterson, Ryan J Leigh, George J F Heigenhauser, Harry B RossiterAbstract:The effect of voluntary hyperventilation-induced hypocapnic alkalosis (RALK) on pulmonary O2 uptake () kinetics and muscle deoxygenation was examined in young male adults (n= 8) during Moderate-Intensity Exercise. Subjects performed five repetitions of a step-transition in work rate from 20 W cycling to a work rate corresponding to 90% of the estimated lactate threshold during control (CON; , ∼40 mmHg) and during hyperventilation (RALK; , ∼20 mmHg). was measured breath-by-breath and relative concentration changes in muscle deoxy- (ΔHHb), oxy- (ΔO2Hb) and total (ΔHbtot) haemoglobin were measured continuously using near-infrared (NIR) spectroscopy (Hamamatsu, NIRO 300). The time constant for the fundamental, phase 2, response (τ) was greater (P < 0.05) in RALK (48 ± 11 s) than CON (31 ± 9 s), while τHHb was similar between conditions (RALK, 12 ± 4 s; CON, 11 ± 4 s). The ΔHbtot was lower (P < 0.05) in RALK than CON, prior to (RALK, −3 ± 5 μmol l−1; CON, −1 ± 4 μmol l−1) and at the end (RALK, 1 ± 6 μmol l−1; CON, 5 ± 5 μmol l−1) of Moderate-Intensity Exercise. Although slower adaptation of during RALK may be related to an attenuated activation of PDH (and other enzymes) and provision of oxidizable substrate to the mitochondria (i.e. metabolic inertia), the present findings also suggest a role for a reduction in local muscle perfusion and O2 delivery.
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Hyperventilation‐induced hypocapnic alkalosis slows the adaptation of pulmonary O2 uptake during the transition to moderate‐intensity Exercise
The Journal of Physiology, 2007Co-Authors: Lisa M K Chin, Donald H. Paterson, Ryan J Leigh, George J F Heigenhauser, Harry B Rossiter, John M. KowalchukAbstract:The effect of voluntary hyperventilation-induced hypocapnic alkalosis (RALK) on pulmonary O2 uptake () kinetics and muscle deoxygenation was examined in young male adults (n= 8) during Moderate-Intensity Exercise. Subjects performed five repetitions of a step-transition in work rate from 20 W cycling to a work rate corresponding to 90% of the estimated lactate threshold during control (CON; , ∼40 mmHg) and during hyperventilation (RALK; , ∼20 mmHg). was measured breath-by-breath and relative concentration changes in muscle deoxy- (ΔHHb), oxy- (ΔO2Hb) and total (ΔHbtot) haemoglobin were measured continuously using near-infrared (NIR) spectroscopy (Hamamatsu, NIRO 300). The time constant for the fundamental, phase 2, response (τ) was greater (P < 0.05) in RALK (48 ± 11 s) than CON (31 ± 9 s), while τHHb was similar between conditions (RALK, 12 ± 4 s; CON, 11 ± 4 s). The ΔHbtot was lower (P < 0.05) in RALK than CON, prior to (RALK, −3 ± 5 μmol l−1; CON, −1 ± 4 μmol l−1) and at the end (RALK, 1 ± 6 μmol l−1; CON, 5 ± 5 μmol l−1) of Moderate-Intensity Exercise. Although slower adaptation of during RALK may be related to an attenuated activation of PDH (and other enzymes) and provision of oxidizable substrate to the mitochondria (i.e. metabolic inertia), the present findings also suggest a role for a reduction in local muscle perfusion and O2 delivery.
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o2 uptake and muscle deoxygenation kinetics during the transition to moderate intensity Exercise in different phases of the menstrual cycle in young adult females
European Journal of Applied Physiology, 2007Co-Authors: B J Gurd, Donald H. Paterson, J Scheid, John M. KowalchukAbstract:O2 uptake \((\dot{V}O_{2})\) kinetics were examined during the follicular (F) and luteal (L) phases of the menstrual cycle to determine if there was an effect of altered sex hormones on the \(\dot{V}O_{2}\) response to Moderate-Intensity Exercise. Seven healthy women (age 21 ± 2 years; mean ± SD) performed six transitions from 20 W to Moderate-Intensity Exercise (∼ 90 % \(\hat{\theta}_{{{\rm L}}}\)) during the F and L phase. \(\dot{V}O_{2}\) was measured breath-by-breath and deoxyhemoglobin/myoglobin (Δ HHb) was determined by near infrared spectroscopy. Progesterone and estrogen were significantly (P < 0.05) elevated during the L compared to F phase. \(\dot{V}O_{2}\) kinetics \((\tau \dot{V}O_{2})\) were not different in the two phases of the menstrual cycle (F, 22 ± 5 s; L, 22 ± 6 s; 95% confidence intervals ±4 s) nor was the time course of the Δ HHb response (F, TD 11 ± 2 s, τ 11 ± 3 s; L, TD 12 ± 2 s, τ 12 ± 11 s; τHHb 95% confidence intervals ±3 s). Respiratory exchange ratio (RER) was not different between phases for baseline or steady-state Exercise and the blood lactate response to Exercise was not different. In conclusion, \(\dot{V}O_{2}\) kinetics at the onset of Moderate-Intensity Exercise are not affected by the phase of the menstrual cycle in young females suggesting either no change in, or no effect of metabolic activation on the on-transient kinetics of Moderate-Intensity Exercise. Additionally, the similar adaptation of Δ HHb in combination with unchanged \(\dot{V}O_{2}\) suggests that there were no differences in the adaptation of local muscle O2 delivery.
Flemming Dela - One of the best experts on this subject based on the ideXlab platform.
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the effect of age and unilateral leg immobilization for 2 weeks on substrate utilization during moderate intensity Exercise in human skeletal muscle
The Journal of Physiology, 2016Co-Authors: Andreas Vigelso, Martin Gram, Rie Dybboe, Anja Birk Kuhlman, Clara Prats, Paul L Greenhaff, Dumitru Constantinteodosiu, Jesper B Birk, Jorgen F P Wojtaszewski, Flemming DelaAbstract:Key points This study aimed to provide molecular insight into the differential effects of age and physical inactivity on the regulation of substrate metabolism during Moderate-Intensity Exercise. Using the arteriovenous balance technique, we studied the effect of immobilization of one leg for 2 weeks on leg substrate utilization in young and older men during two-legged dynamic knee-extensor Moderate-Intensity Exercise, as well as changes in key proteins in muscle metabolism before and after Exercise. Age and immobilization did not affect relative carbohydrate and fat utilization during Exercise, but the older men had higher uptake of exogenous fatty acids, whereas the young men relied more on endogenous fatty acids during Exercise. Using a combined whole-leg and molecular approach, we provide evidence that both age and physical inactivity result in intramuscular lipid accumulation, but this occurs only in part through the same mechanisms. Abstract Age and inactivity have been associated with intramuscular triglyceride (IMTG) accumulation. Here, we attempt to disentangle these factors by studying the effect of 2 weeks of unilateral leg immobilization on substrate utilization across the legs during Moderate-Intensity Exercise in young (n = 17; 23 ± 1 years old) and older men (n = 15; 68 ± 1 years old), while the contralateral leg served as the control. After immobilization, the participants performed two-legged isolated knee-extensor Exercise at 20 ± 1 W (∼50% maximal work capacity) for 45 min with catheters inserted in the brachial artery and both femoral veins. Biopsy samples obtained from vastus lateralis muscles of both legs before and after Exercise were used for analysis of substrates, protein content and enzyme activities. During Exercise, leg substrate utilization (respiratory quotient) did not differ between groups or legs. Leg fatty acid uptake was greater in older than in young men, and although young men demonstrated net leg glycerol release during Exercise, older men showed net glycerol uptake. At baseline, IMTG, muscle pyruvate dehydrogenase complex activity and the protein content of adipose triglyceride lipase, acetyl-CoA carboxylase 2 and AMP-activated protein kinase (AMPK)γ3 were higher in young than in older men. Furthermore, adipose triglyceride lipase, plasma membrane-associated fatty acid binding protein and AMPKγ3 subunit protein contents were lower and IMTG was higher in the immobilized than the contralateral leg in young and older men. Thus, immobilization and age did not affect substrate choice (respiratory quotient) during moderate Exercise, but the whole-leg and molecular differences in fatty acid mobilization could explain the age- and immobilization-induced IMTG accumulation.
David Brian Abrams - One of the best experts on this subject based on the ideXlab platform.
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The efficacy of moderate intensity Exercise as an aid for smoking cessation in women: A randomized controlled trial
Nicotine and Tobacco Research, 2005Co-Authors: Bess H. Marcus, Beth A. Lewis, Joseph Hogan, Teresa K. King, Anna E. Albrecht, Beth Bock, Raymond Niaura, Alfred F Parisi, David Brian AbramsAbstract:Evidence suggests that vigorous-intensity Exercise interventions may be effective for smoking cessation among women; however, few studies have examined the efficacy of a Moderate-Intensity Exercise program. The present study examined the efficacy of Moderate-Intensity Exercise for smoking cessation among female smokers. Healthy, sedentary female smokers (N = 217) were randomly assigned to an 8-week cognitive-behavioral smoking cessation program plus Moderate-Intensity Exercise (CBT+EX) or to the same cessation program plus equal contact (CBT). A subsample received nicotine replacement therapy. Results indicated that the CBT+EX and CBT groups were equally likely to attain smoking cessation at the end of treatment, as measured by cotinine-verified 7-day point-prevalence abstinence (20.2% for CBT+EX vs. 18.5% for CBT). The CBT+EX group was more likely to report smoking cessation, as measured by 7-day point prevalence at the 3-month follow-up (11.9% vs. 4.6%, p
Bess H. Marcus - One of the best experts on this subject based on the ideXlab platform.
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Moderate intensity Exercise as an adjunct to standard smoking cessation treatment for women: a pilot study.
Psychology of Addictive Behaviors, 2010Co-Authors: David M. Williams, Anna E. Albrecht, Alfred F Parisi, Jessica A. Whiteley, Shira Dunsiger, Ernestine Jennings, Michael Ussher, Joseph T. Ciccolo, Bess H. MarcusAbstract:Previous randomized controlled trials have not supported moderate intensity Exercise as an efficacious adjunct to smoking cessation treatments for women; however, compliance with Exercise programs in these studies has been poor. The purpose of this pilot study was to estimate the effects of moderate intensity Exercise on smoking cessation outcomes under optimal conditions for Exercise program compliance. Sixty previously sedentary, healthy, female smokers were randomized to an 8-week program consisting of brief baseline smoking cessation counseling and the nicotine patch plus either 150 min/week of moderate intensity Exercise or contact control. Participants attended a median of 86.4% and 95.5% of prescribed Exercise/control sessions, respectively. There was a moderate, though statistically nonsignificant, effect of Exercise at post-treatment for objectively verified 7-day point prevalence abstinence (48.3% vs. 23.3%; OR 3.07, 95% CI: 0.89–11.07) and prolonged abstinence (34.5% vs. 20.0%; OR 2.11, 95% CI: 0.56–8.32). Effects were attenuated when controlling for potential confounders, and after a 1-month, no-treatment period. The findings provide a preliminary indication that, given adequate compliance, moderate intensity Exercise may enhance short-term smoking cessation outcomes for women; however, a larger trial is warranted.
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Acute Affective Response to a Moderate-Intensity Exercise Stimulus Predicts Physical Activity Participation 6 and 12 Months Later.
Psychology of Sport and Exercise, 2008Co-Authors: David M. Williams, Beth A. Lewis, Anna E. Albrecht, Shira Dunsiger, Joseph T. Ciccolo, Bess H. MarcusAbstract:Abstract Objective Examine the relationship between acute affective responses during a Moderate-Intensity Exercise stimulus and future physical activity participation. Design Longitudinal, observational study in the context of a randomized controlled trial. Methods Healthy, sedentary adults (n=37) reported their basic affective response (i.e., feel good versus bad) prior to and during an acute, Moderate-Intensity Exercise stimulus presented prior to randomization in a controlled physical activity promotion trial. At 6 and 12 months, 31 of the 37 participants reported their total weekly minutes of physical activity. Results As hypothesized, basic affective response to the Moderate-Intensity stimulus predicted 6-month physical activity (β=.51, p=.013) when controlling for baseline physical activity and self-reported affect prior to the initial Exercise stimulus, and 12-month physical activity (β=.45, p=.047) when also controlling for 6-month physical activity. Conclusions Affective response to an acute Moderate-Intensity Exercise stimulus predicted self-reported physical activity 6 and 12 months later. The findings could have implications for prescription of Exercise intensity, as exercising at an intensity that yields a positive affective response may lead to greater participation in physical activity programs among previously sedentary adults.
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The efficacy of moderate intensity Exercise as an aid for smoking cessation in women: A randomized controlled trial
Nicotine and Tobacco Research, 2005Co-Authors: Bess H. Marcus, Beth A. Lewis, Joseph Hogan, Teresa K. King, Anna E. Albrecht, Beth Bock, Raymond Niaura, Alfred F Parisi, David Brian AbramsAbstract:Evidence suggests that vigorous-intensity Exercise interventions may be effective for smoking cessation among women; however, few studies have examined the efficacy of a Moderate-Intensity Exercise program. The present study examined the efficacy of Moderate-Intensity Exercise for smoking cessation among female smokers. Healthy, sedentary female smokers (N = 217) were randomly assigned to an 8-week cognitive-behavioral smoking cessation program plus Moderate-Intensity Exercise (CBT+EX) or to the same cessation program plus equal contact (CBT). A subsample received nicotine replacement therapy. Results indicated that the CBT+EX and CBT groups were equally likely to attain smoking cessation at the end of treatment, as measured by cotinine-verified 7-day point-prevalence abstinence (20.2% for CBT+EX vs. 18.5% for CBT). The CBT+EX group was more likely to report smoking cessation, as measured by 7-day point prevalence at the 3-month follow-up (11.9% vs. 4.6%, p