Oxygen availability and PCr recovery rate in untrained human calf muscle: evidence of metabolic limitation in normoxia

2007 ◽  
Vol 293 (5) ◽  
pp. R2046-R2051 ◽  
Author(s):  
Luke J. Haseler ◽  
Alexander Lin ◽  
Jan Hoff ◽  
Russell S. Richardson
Keyword(s):  
Rate Constant ◽  
Recovery Rate ◽  
Plantar Flexion ◽  
Ambient Air ◽  
Oxidative Capacity ◽  
Resonance Spectroscopy ◽  
Average Value ◽  
A Value ◽  
Maximal Metabolic Rate ◽  
Oxidative Rate

In contrast to their exercise-trained counterparts, the maximal oxidative rate of skeletal muscle in sedentary humans appears not to benefit from supplemental O2 availability but is impacted by severe hypoxia, suggesting a metabolic limitation either at or below ambient O2 levels. However, the critical level of O2 availability at which maximal metabolic rate is reduced in sedentary humans is unknown. Using 31P magnetic resonance spectroscopy and arterial oximetry, phosphocreatine (PCr) recovery kinetics and arterial oxygenation were assessed in six sedentary subjects performing 5-min bouts of plantar flexion exercise followed by 6 min of recovery. Each trial was repeated while breathing one of four different fractions of inspired O2 (FIO2) (0.10, 0.12, 0.15, and 0.21). The PCr recovery rate constant (a marker of oxidative capacity) was unaffected by reductions in FIO2, remaining at a value of 1.5 ± 0.2 min−1 until arterial O2 saturation (SaO2) fell to less than ∼92%, the average value reached breathing an FIO2 of 0.15. Below this SaO2, the PCr rate constant fell significantly by 13 and 31% to 1.3 ± 0.2 and 1.0 ± 0.2 min−1 ( P < 0.05) as SaO2 was reduced to 82 ± 3 and 77 ± 2%, respectively. In conclusion, this study has revealed that O2 availability does not impact maximal oxidative rate in sedentary humans until the O2 level falls well below that of ambient air, indicating a metabolic limitation in normoxia.

Skeletal muscle oxidative metabolism in sedentary humans: 31P-MRS assessment of O2 supply and demand limitations

2004 ◽  
Vol 97 (3) ◽  
pp. 1077-1081 ◽  
Author(s):  
Luke J. Haseler ◽  
Alexander P. Lin ◽  
Russell S. Richardson
Keyword(s):  
Gastrocnemius Muscle ◽  
Supply And Demand ◽  
Plantar Flexion ◽  
Submaximal Exercise ◽  
Resonance Spectroscopy ◽  
O2 Supply ◽  
Sedentary Subjects ◽  
Mitochondrial Capacity ◽  
Oxidative Rate ◽  
Plantar Flexion Exercise

Previously, it was demonstrated in exercise-trained humans that phosphocreatine (PCr) recovery is significantly altered by fraction of inspired O2 (FiO2), suggesting that in this population under normoxic conditions, O2 availability limits maximal oxidative rate. Haseler LJ, Hogan ML, and Richardson RS. J Appl Physiol 86: 2013–2018, 1999. To further elucidate these population-specific limitations to metabolic rate, we used 31P-magnetic resonance spectroscopy to study the exercising human gastrocnemius muscle under conditions of varied FiO2 in sedentary subjects. To test the hypothesis that PCr recovery from submaximal exercise in sedentary subjects is not limited by O2 availability, but rather by their mitochondrial capacity, six sedentary subjects performed three bouts of 6-min steady-state submaximal plantar flexion exercise followed by 5 min of recovery while breathing three different FiO2 (0.10, 0.21, and 1.00). PCr recovery time constants were significantly longer in hypoxia (47.0 ± 3.2 s), but there was no difference between hyperoxia (31.8 ± 1.9 s) and normoxia (30.0 ± 2.1 s) (mean ± SE). End-exercise pH was not significantly different across treatments. These results suggest that the maximal muscle oxidative rate of these sedentary subjects, unlike their exercise-trained counterparts, is limited by mitochondrial capacity and not O2 availability in normoxia. Additionally, the significant elongation of PCr recovery in these subjects in hypoxia illustrates the reliance on O2 supply at the other end of the O2 availability spectrum in both sedentary and active populations.

Skeletal muscle phosphocreatine recovery in exercise-trained humans is dependent on O2availability

1999 ◽  
Vol 86 (6) ◽  
pp. 2013-2018 ◽  
Author(s):  
Luke J. Haseler ◽  
Michael C. Hogan ◽  
Russell S. Richardson
Keyword(s):  
Skeletal Muscle ◽  
Oxidative Metabolism ◽  
Gastrocnemius Muscle ◽  
Plantar Flexion ◽  
Oxidative Capacity ◽  
Submaximal Exercise ◽  
Resonance Spectroscopy ◽  
The Relationship ◽  
Male Subjects ◽  
Plantar Flexion Exercise

In skeletal muscle, phosphocreatine (PCr) recovery from submaximal exercise has become a reliable and accepted measure of muscle oxidative capacity. During exercise, O2 availability plays a role in determining maximal oxidative metabolism, but the relationship between O2 availability and oxidative metabolism measured by31P-magnetic resonance spectroscopy (MRS) during recovery from exercise has never been studied. We used 31P-MRS to study exercising human gastrocnemius muscle under conditions of varied fractions of inspired O2 [Formula: see text]) to test the hypothesis that varied O2availability modulates PCr recovery from submaximal exercise. Six male subjects performed three bouts of 5-min steady-state submaximal plantar flexion exercise followed by 5 min of recovery in a 1.5-T magnet while breathing three different[Formula: see text] concentrations (0.10, 0.21, and 1.00). Under each[Formula: see text] treatment, the PCr recovery time constants were significantly different, being longer in hypoxia [33.5 ± 4.1 s (SE)] and shorter in hyperoxia (20.0 ± 1.8 s) than in normoxia (25.0 ± 2.7 s) ( P ≤ 0.05). End-exercise pH was not significantly different among the three treatments (7.08 ± 0.01 for 0.10, 7.04 ± 0.01 for 0.21, and 7.04 ± 0.02 for 1.00). These results demonstrate that PCr recovery is significantly altered by[Formula: see text] and suggest that, after submaximal exercise, PCr recovery, under normoxic conditions, is limited by O2 availability.

Muscle metabolism in track athletes, using 31P magnetic resonance spectroscopy

1992 ◽  
Vol 70 (10) ◽  
pp. 1353-1359 ◽  
Author(s):  
Kevin K. McCully ◽  
Krista Vandenborne ◽  
Kenny DeMeirleir ◽  
Joel D. Posner ◽  
John S. Leigh Jr.
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Plantar Flexion ◽  
Muscle Metabolism ◽  
Oxidative Capacity ◽  
Resonance Spectroscopy ◽  
Distance Runners ◽  
Long Distance ◽  
Muscle Weight ◽  
Track Athletes

We tested whether preferred running event in track athletes would correlate with the initial rate of phosphocreatine (PCr) resynthesis following submaximal exercise. PCr recovery was measured in the calf muscles of 16 male track athletes and 7 male control subjects following 5 min of repeated plantar flexion against resistance. Pi, PCr, and pH were measured using phosphorus magnetic resonance spectroscopy (31P MRS) with an 8-cm surface coil in a 1.8-T magnet. During exercise, work levels were gradually increased to deplete PCr to 50–60% of the initial value. No drop in pH was seen in any of the subjects during this exercise. The areas of the PCr peaks following exercise were fit to monoexponential curves. Two or three tests were performed on each subject and the results averaged. Athletes were divided into three groups based on their primary event: sprinters running 400 m or less, middle-distance athletes running 400–1500 m, and long-distance athletes running farther than 1500 m. The maximal rates of PCr resynthesis (mmol∙min−1∙kg−1 muscle weight) were 64.8 ± 8.6, for long-distance runners; 41.4 ± 11, for middle-distance runners; 32.0 ± 7.0, for sprinters; and 38.6 ± 10, for controls (mean ± SE). The faster PCr recovery rates seen in long-distance runners compared with sprinters indicate greater oxidative capacity, which is consistent with the known differences between athletes in these events.Key words: exercise recovery, human, phosphocreatine.

scholarly journals A cross-validation of near-infrared spectroscopy measurements of skeletal muscle oxidative capacity with phosphorus magnetic resonance spectroscopy

2013 ◽  
Vol 115 (12) ◽  
pp. 1757-1766 ◽  
Author(s):  
Terence E. Ryan ◽  
W. Michael Southern ◽  
Mary Ann Reynolds ◽  
Kevin K. McCully
Keyword(s):  
Skeletal Muscle ◽  
Near Infrared ◽  
Plantar Flexion ◽  
Oxidative Capacity ◽  
Resonance Spectroscopy ◽  
Time Constants ◽  
Muscle Oxidative Capacity ◽  
Muscle Oxygen ◽  
Muscle Oxygen Consumption ◽  
Plantar Flexion Exercise

The purpose of this study was to cross-validate measurements of skeletal muscle oxidative capacity made with near-infrared spectroscopy (NIRS) measurements to those made with phosphorus magnetic resonance spectroscopy (31P-MRS). Sixteen young (age = 22.5 ± 3.0 yr), healthy individuals were tested with both 31P-MRS and NIRS during a single testing session. The recovery rate of phosphocreatine was measured inside the bore of a 3-Tesla MRI scanner, after short-duration (∼10 s) plantar flexion exercise as an index of skeletal muscle oxidative capacity. Using NIRS, the recovery rate of muscle oxygen consumption was also measured using repeated, transient arterial occlusions outside the MRI scanner, after short-duration (∼10 s) plantar flexion exercise as another index of skeletal muscle oxidative capacity. The average recovery time constant was 31.5 ± 8.5 s for phosphocreatine and 31.5 ± 8.9 s for muscle oxygen consumption for all participants ( P = 0.709). 31P-MRS time constants correlated well with NIRS time constants for both channel 1 (Pearson's r = 0.88, P < 0.0001) and channel 2 (Pearson's r = 0.95, P < 0.0001). Furthermore, both 31P-MRS and NIRS exhibit good repeatability between trials (coefficient of variation = 8.1, 6.9, and 7.9% for NIRS channel 1, NIRS channel 2, and 31P-MRS, respectively). The good agreement between NIRS and 31P-MRS indexes of skeletal muscle oxidative capacity suggest that NIRS is a valid method for assessing mitochondrial function, and that direct comparisons between NIRS and 31P-MRS measurements may be possible.

Linear dependence of muscle phosphocreatine kinetics on oxidative capacity

1997 ◽  
Vol 272 (2) ◽  
pp. C501-C510 ◽  
Author(s):  
A. T. Paganini ◽  
J. M. Foley ◽  
R. A. Meyer
Keyword(s):  
Rate Constant ◽  
Atp Hydrolysis ◽  
Citrate Synthase ◽  
Respiratory Control ◽  
Oxidative Capacity ◽  
Resonance Spectroscopy ◽  
Mitochondrial Enzymes ◽  
Control Groups ◽  
Significant Linear Correlation ◽  
Isometric Twitch

The influence of muscle oxidative capacity on phosphocreatine (PCr) changes during and after stimulation was examined in the superficial (fast-twitch) section of rat gastrocnemius muscles. Muscle mitochondrial enzymes were increased in one group of rats by 8-10 wk of training on a running wheel (to a final regimen of 50 min/day at 38 m/min, 5 days/wk) and decreased in another group by chemical thyroidectomy [0.025% methimazole (MMI) in drinking water for 8 wk]. After these treatments, muscle citrate synthase activity was 179 and 29%, respectively, of that in corresponding control groups. Muscle PCr and pH were measured by 31P-nuclear magnetic resonance spectroscopy before, during, and after 8 min of isometric twitch stimulation at 0.33 Hz (MMI) or 0.75 Hz (trained) and 2 Hz. There was a significant linear correlation (r = 0.84, P < 0.01) between the rate constant for PCr recovery after submaximal stimulation (0.33 or 0.75 Hz) and citrate synthase activity. Within the control groups, there was a significant correlation (r = 0.72, P < 0.01) between the rate constant for PCr recovery and intracellular pH at the end of stimulation. The results are quantitatively consistent with linear/quasilinear models of respiratory control by the cytoplasmic free energy of ATP hydrolysis but not with respiratory control by cytoplasmic ADP.

scholarly journals Poor Mitochondrial Health and Systemic Inflammation? Testing of a Classical Hypothesis

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 126-127
Author(s):  
Marta Zampino ◽  
Luigi Ferrucci ◽  
Richard Spencer ◽  
Kenneth Fishbein ◽  
Eleanor Simonsick ◽  
...  
Keyword(s):  
Mitochondrial Function ◽  
Fat Body ◽  
Reference Group ◽  
Linear Regression Analysis ◽  
Oxidative Capacity ◽  
Conclusive Evidence ◽  
Resonance Spectroscopy ◽  
Low Grade ◽  
Severe Impairment

Abstract Chronic low-grade inflammation often occurs with aging and has been associated with negative health outcomes. Despite extensive research on the origins of “inflammaging”, the causative mechanisms remain unclear. However, a connection between poor mitochondrial health and chronic inflammation has been hypothesized, with decreasing mitochondrial function occurring with age and precipitating an increase in reactive oxygen species and other pro-inflammatory macromolecules such as mitochondrial DNA. We tested this hypothesis on a population of 619 subjects from the Baltimore Longitudinal Study of Aging, measuring muscle mitochondrial oxidative capacity in vivo by phosphorus magnetic resonance spectroscopy (P-MRS), and plasma interleukin (IL)-6, the most widely used biomarker of inflammaging. The P-MRS-derived post-exercise phosphocreatine recovery time constant tau-PCr, a measure of oxidative capacity, was expressed as a categorical variable through assignment to quintiles. Participants in the first quintile of tau-PCr (best mitochondrial function) were taken as reference and compared to the others using linear regression analysis adjusted for sex, age, lean and fat body mass, and physical activity. Those participants with the lowest oxidative capacity had significantly higher log(IL-6) levels as compared to the reference group. However, data from the other quintiles was not significantly different from the reference values. In conclusion, severe impairment of oxidative capacity is associated with increased inflammation. This study design does not provide conclusive evidence of whether increased inflammation and impaired bioenergetic recovery are both caused by underlying poor health status, or whether mitochondrial deficits lead directly to the observed inflammation; we anticipate addressing this important question with longitudinal studies.

scholarly journals Systemic oxidative stress is associated with lower aerobic capacity and impaired skeletal muscle energy metabolism in heart failure patients

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Takashi Yokota ◽  
Shintaro Kinugawa ◽  
Kagami Hirabayashi ◽  
Mayumi Yamato ◽  
Shingo Takada ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Heart Failure ◽  
Skeletal Muscle ◽  
Energy Metabolism ◽  
Aerobic Capacity ◽  
Plantar Flexion ◽  
Exercise Intolerance ◽  
Whole Body ◽  
Resonance Spectroscopy ◽  
Systemic Oxidative Stress

AbstractOxidative stress plays a role in the progression of chronic heart failure (CHF). We investigated whether systemic oxidative stress is linked to exercise intolerance and skeletal muscle abnormalities in patients with CHF. We recruited 30 males: 17 CHF patients, 13 healthy controls. All participants underwent blood testing, cardiopulmonary exercise testing, and magnetic resonance spectroscopy (MRS). The serum thiobarbituric acid reactive substances (TBARS; lipid peroxides) were significantly higher (5.1 ± 1.1 vs. 3.4 ± 0.7 μmol/L, p < 0.01) and the serum activities of superoxide dismutase (SOD), an antioxidant, were significantly lower (9.2 ± 7.1 vs. 29.4 ± 9.7 units/L, p < 0.01) in the CHF cohort versus the controls. The oxygen uptake (VO2) at both peak exercise and anaerobic threshold was significantly depressed in the CHF patients; the parameters of aerobic capacity were inversely correlated with serum TBARS and positively correlated with serum SOD activity. The phosphocreatine loss during plantar-flexion exercise and intramyocellular lipid content in the participants' leg muscle measured by 31phosphorus- and 1proton-MRS, respectively, were significantly elevated in the CHF patients, indicating abnormal intramuscular energy metabolism. Notably, the skeletal muscle abnormalities were related to the enhanced systemic oxidative stress. Our analyses revealed that systemic oxidative stress is related to lowered whole-body aerobic capacity and skeletal muscle dysfunction in CHF patients.

scholarly journals Evidence that a higher ATP cost of muscular contraction contributes to the lower mechanical efficiency associated with COPD: preliminary findings

2011 ◽  
Vol 300 (5) ◽  
pp. R1142-R1147 ◽  
Author(s):  
Gwenael Layec ◽  
Luke J. Haseler ◽  
Jan Hoff ◽  
Russell S. Richardson
Keyword(s):  
Skeletal Muscle ◽  
Muscle Contraction ◽  
Energy Cost ◽  
Plantar Flexion ◽  
Mechanical Efficiency ◽  
Exercise Intolerance ◽  
Chronic Obstructive ◽  
Small Subset ◽  
Resonance Spectroscopy ◽  
Muscle Energetics

Impaired metabolism in peripheral skeletal muscles potentially contributes to exercise intolerance in chronic obstructive pulmonary disease (COPD). We used 31P-magnetic resonance spectroscopy (31P-MRS) to examine the energy cost and skeletal muscle energetics in six patients with COPD during dynamic plantar flexion exercise compared with six well-matched healthy control subjects. Patients with COPD displayed a higher energy cost of muscle contraction compared with the controls (control: 6.1 ± 3.1% of rest·min−1·W−1, COPD: 13.6 ± 8.3% of rest·min−1·W−1, P = 0.01). Although, the initial phosphocreatine resynthesis rate was also significantly attenuated in patients with COPD compared with controls (control: 74 ± 17% of rest/min, COPD: 52 ± 13% of rest/min, P = 0.04), when scaled to power output, oxidative ATP synthesis was similar between groups (6.5 ± 2.3% of rest·min−1·W−1 in control and 7.8 ± 3.9% of rest·min−1·W−1 in COPD, P = 0.52). Therefore, our results reveal, for the first time that in a small subset of patients with COPD a higher ATP cost of muscle contraction may substantially contribute to the lower mechanical efficiency previously reported in this population. In addition, it appears that some patients with COPD have preserved mitochondrial function and normal energy supply in lower limb skeletal muscle.

EFFECT OF ZINK TABLETS INTERVENTION IN ZINC DEFICIENCY OF TRIMESTER III PREGNANT WOMEN TOWARD WEIGHT AND BODY LENGTH OF NEWBORN

2021 ◽  
Vol 10 (2) ◽  
pp. 304-312
Author(s):  
Nurfadillah S ◽  
Wardihan Sinrang ◽  
Suryani As'ad ◽  
Muh. Nasrum Massi ◽  
Mardiana Ahmad ◽  
...  
Keyword(s):  
Birth Weight ◽  
Pregnant Women ◽  
Zinc Deficiency ◽  
Birth Length ◽  
World Health ◽  
Third Trimester ◽  
Average Value ◽  
The Third ◽  
A Value ◽  
Zinc Levels

Background: According to 2018 World Health Organization (WHO) data globally, an estimated 17.3% of the population has inadequate zinc intake, with estimates ranging from 5.7% in Oceania to 7.6% in Europe, 9.6% in America and the Caribbean, highest in Africa (23.9%) and Asia (19.6%). Zinc is important for the function of a number of enzymes and growth hormones during pregnancy. In pregnant women, the relative zinc concentration decreases up to 35% due to the influence of hormonal changes and the transport of nutrients from mother to baby. Objectives: The purpose of this study was to identify the effect of giving zinc tablets to pregnant women with zinc deficiency in the third trimester on body weight and length of babies born at the Makassar City Health Center. Methods: This type of research is True Experimental with a pretest-posttest design with a control group. The sample in this study was 62 samples of third trimester pregnant women, and the sampling technique used was purposive sampling. Measurement of zinc levels in third trimester pregnant women using the Elisa reader kit at the Research Laboratory of the Hasanuddin University Teaching Hospital. The research instruments were in the form of a research explanation sheet, respondent's consent sheet, respondent's checklist sheet, and the mother's zinc tablet consumption control sheet for 14 days. Results: Judging from the average value of newborns in pregnant women who did not have zinc deficiency, the average value of birth weight in pregnant women with zinc deficiency was 15.70 g/dL and 18.95 g/dL. zinc deficiency with a value (p < 0.05), while pregnant women with zinc deficiency have an average birth length of 10.00 g/dL and mothers who do not have a deficiency of 19.87 g/dL with a value (p < 0.05). So, it can be concluded that giving zinc tablets to pregnant women in the third trimester has an effect on Birth Weight (BBL) and Birth Length (PBL). Conclusion: Giving zinc tablets has an effect on increasing zinc levels in third trimester zinc deficiency pregnant women and increasing birth weight and length of the baby.  

Muscle metabolism during exercise in young and older untrained and endurance-trained men

1993 ◽  
Vol 75 (5) ◽  
pp. 2125-2133 ◽  
Author(s):  
A. R. Coggan ◽  
A. M. Abduljalil ◽  
S. C. Swanson ◽  
M. S. Earle ◽  
J. W. Farris ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Muscle Mass ◽  
Citrate Synthase ◽  
Metabolic Response ◽  
Plantar Flexion ◽  
Muscle Metabolism ◽  
Resonance Spectroscopy ◽  
Age Related ◽  
Rate Of Increase ◽  
Response To Exercise

To examine effects of aging and endurance training on human muscle metabolism during exercise, 31P magnetic resonance spectroscopy was used to study the metabolic response to exercise in young (21–33 yr) and older (58–68 yr) untrained and endurance-trained men (n = 6/group). Subjects performed graded plantar flexion exercise with the right leg, with metabolic responses measured using a 31P surface coil placed over the lateral head of the gastrocnemius muscle. Muscle biopsy samples were also obtained for determination of citrate synthase activity. Rate of increase in P(i)-to-phosphocreatine ratio with increasing power output was greater (P < 0.01) in older untrained [0.058 +/- 0.022 (SD) W-1] and trained men (0.042 +/- 0.010 W-1) than in young untrained (0.038 +/- 0.017 W-1) and trained men (0.024 +/- 0.010 W-1). Plantar flexor muscle cross-sectional area and volume (determined using 1H magnetic resonance imaging) were 11–12% (P < 0.05) and 16–18% (P < 0.01) smaller, respectively, in older men. When corrected for this difference in muscle mass, age-related differences in metabolic response to exercise were reduced by approximately 50% but remained significant (P < 0.05). Citrate synthase activity was approximately 20% lower (P < 0.001) in older untrained and trained men than in corresponding young groups and was inversely related to P(i)-phosphocreatine slope (r = -0.63, P < 0.001). Age-related reductions in exercise capacity were associated with an altered muscle metabolic response to exercise, which appeared to be due to smaller muscle mass and lower muscle respiratory capacity of older subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

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