Post-exercise Oxygen Consumption Rates Research Articles

Noninvasive Assessments of Mitochondrial Capacity in People with Mitochondrial Myopathies

People affected by mitochondrial myopathies (MITOs) are thought to have impaired skeletal muscle oxygenation. The aims of this study were to measure skeletal muscle mitochondrial capacity in MITO participants and able-bodied (AB) participants and evaluate the influence of muscle-specific endurance training in one MITO participant. Participants (n = 7) with mitochondrial disease and controls (n = 9) were tested (ages 18–54 years). Mitochondrial capacity (mVO2max) was measured using the rate constant of recovery of oxygen consumption (mVO2) after exercise in the forearm flexor muscles with near-infrared spectroscopy (NIRS). One MITO participant was tested before and after performing 18 forearm exercise sessions in 30 days. There were no differences between MITO and AB participants in mVO2max (MITO: 1.4 ± 0.1 min−1; AB: 1.5 ± 0.3 min−1; p = 0.29), resting mVO2 (MITO: −0.4 ± 0.2%/min; AB: −0.3 ± 0.1%/min; p = 0.23), or initial post exercise oxygen consumption rates (MITO: 4.3 ± 1.2%/min; AB: 4.4 ± 1.4%/min; p = 0.9). Exercise oxygen desaturation was greater in MITO (39.8 ± 9.7% range) than in AB (28 ± 8.8% range) participants, p = 0.02. The MITO participant who trained increased her mitochondrial capacity (58%) and muscle-specific endurance (24%) and had reduced symptoms of muscle fatigue. We found no evidence supporting in vivo impairment of forearm muscle mVO2max in genetically confirmed MITO participants. This is consistent with studies that report increased mitochondrial content, which offsets the decrease in mitochondrial function. Positive muscle adaptations to endurance training appear to be possible in people with MITOs. Characterization of study populations will be important when interpreting the relationship between in vivo mitochondrial capacity and mitochondrial disease.

The Impact of Starting Positions and Breathing Rhythms on Cardiopulmonary Stress and Post-Exercise Oxygen Consumption after High-Intensity Metabolic Training: A Randomized Crossover Prospective Study.

Background: The exploration of optimizing cardiopulmonary function and athletic performance through high-intensity metabolic exercises (HIMEs) is paramount in sports science. Despite the acknowledged efficacy of HIMEs in enhancing cardiopulmonary endurance, the high metabolic stress imposed on the cardiopulmonary system, especially for amateurs, necessitates a scaled approach to training. Objective: The aim of this study is to ascertain whether adjustments in the initiation posture and the adoption of an appropriate breathing strategy can effectively mitigate the cardiopulmonary stress induced by HIMEs without compromising training efficacy. Methods: Twenty-two subjects were recruited into this study. The post-exercise heart rate (PHR) and post-exercise oxygen consumption rate (POCR) were collected within 30 min after exercise. A two-way ANOVA, multi-variable Cox regression, and random survival forest machine learning algorithm were used to conduct the statistical analysis. Results: Under free breathing, only the maximum POCR differed significantly between standing and prone positions, with prone positions showing higher stress (mean difference = 3.15, p < 0.001). In contrast, the regulated breathing rhythm enhanced performance outcomes compared to free breathing regardless of the starting position. Specifically, exercises initiated from prone positions under regulated breathing recorded a significantly higher maximum and average PHR than those from standing positions (maximum PHR: mean difference = 13.40, p < 0.001; average PHR: mean difference = 6.45, p < 0.001). The multi-variable Cox regression highlighted the starting position as a critical factor influencing the PHR and breathing rhythm as a significant factor for the POCR, with respective variable importances confirmed by the random survival forest analysis. These results underscore the importance of controlled breathing and starting positions in optimizing HIME outcomes. Conclusions: Regulated breathing in high-intensity exercises enhances performance and physiological functions, emphasizing the importance of breathing rhythm over starting position. Effective training should balance exercise volume and technique to optimize performance and minimize stress, reducing overtraining and injury risks.

Effect of temperature on excess post-exercise oxygen consumption in juvenile southern catfish (Silurus meridionalis Chen) following exhaustive exercise

The effects of temperature on resting oxygen consumption rate (MO2rest) and excess post-exercise oxygen consumption (EPOC) after exhaustive exercise (chasing) were measured in juvenile southern catfish (Silurus meridionalis) (8.40±0.30 g, n=40) to test whether temperature has a significant influence on MO2rest, maximum post-exercise oxygen consumption rate (MO2peak) and EPOC and to investigate how metabolic scope (MS: MO2peak - MO2rest) varies with acclimation temperature. The MO2rest increased from 64.7 (10°C) to 160.3 mg O2 h(-1) kg(-1) (25°C) (P<0.05) and reached a plateau between 25 and 30°C. The post-exercise MO2 in all temperature groups increased immediately to the peak values and then decreased slowly to a steady state that was higher than the pre-exercise MO2. The MO2peak did not significantly differ among the 20, 25 and 30°C groups, though these values were much higher than those of the lower temperature groups (10 and 15°C) (P<0.05). The duration of EPOC varied from 32.9 min at 10°C to 345 min at 20°C, depending on the acclimation temperatures. The MS values of the lower temperature groups (10 and 15°C) were significantly smaller than those of the higher temperature groups (20, 25 and 30°C) (P<0.05). The magnitude of EPOC varied ninefold among all of the temperature groups and was the largest for the 20°C temperature group (about 422.4 mg O2 kg(-1)). These results suggested that (1) the acclimation temperature had a significant effect on maintenance metabolism (as indicated by MO2rest) and the post-exercise metabolic recovery process (as indicated by MO2peak, duration and magnitude of EPOC), and (2) the change of the MS as a function of acclimation temperature in juvenile southern catfish might be related to their high degree of physiological flexibility, which allows them to adapt to changes in environmental conditions in their habitat in the Yangtze River and the Jialing River.

The effect of exhaustive exercise training on resting oxygen consumption and post-exercise oxygen consumption rate in southern catfish ( Silurus meridionalis chen)

The resting oxygen consumption rate ( VO 2rest) and post-exercise VO 2 in southern catfish fed on maintenance rations (1.5% body mass per day) or fasted during 15 d of exhaustive exercise training (5 min chasing) and a subsequent 5 d without training was investigated at 25 °C. Two groups kept under the same conditions without exercise training acted as feeding and fasting controls. The VO 2rest values of both feeding and fasting controls decreased significantly during the experiment ( p < 0.05), while those of the feeding and fasting training groups were significantly increased after 15 d of training ( p < 0.05). VO 2rest of both training groups decreased significantly to control levels after training was stopped. The VO 2peak values of both feeding and fasting controls decreased significantly during the experiment ( p < 0.05), while those of the feeding and fasting training groups were unchanged after 15 d of training ( p < 0.05). VO 2peak of both training groups decreased significantly to control levels after training was stopped. There were no significant differences in either VO 2peak/ VO 2rest or excess post-exercise VO 2 (EPOC) among any groups. It is suggested that: (1) VO 2rest and VO 2peak were significantly improved by exercise training compared with the control groups, but returned to their previous values 5 d after stopping training; (2) post-exercise VO 2 recovered faster in training groups compared with control groups, and this trait persisted 5 d after stopping training; (3) training had similar physiological effects on feeding and fasting southern catfish, except that VO 2rest was more sensitive to training in the fasting group; (4) the main effect of training on the post-exercise VO 2 recovery process was the shape of post-exercise VO 2 curve rather than the EPOC.

Swimming Performance, Metabolic Rates, and Their Correlates in the Iceland ScallopChlamys islandica

The dramatic escape response of some scallops is modified by reproductive investment and by acclimation temperature. Despite considerable knowledge of the physiology of the escape response, functional links between escape response performance, organismal rates of oxygen uptake, and tissue metabolic capacities are little known. We measured oxygen consumption rates (standard, maximal, and aerobic scope), escape behavior (initial and repeat performance), tissue mass, condition index, protein content, and tissue metabolic capacities in the Iceland scallop Chlamys islandica to examine links between these parameters. Postexercise oxygen consumption rates were positively linked to contraction rate (repeat test) and to pyruvate kinase activity in the adductor muscle but negatively linked to digestive gland wet mass. Swimming behavior was mainly related to activity of glycolytic enzymes, and enzymatic activities were related to anatomic parameters. Scallop behavior and physiology change with size, both within our samples and on a larger scale. Small scallops showed more intense swimming activity and had higher arginine kinase activities but lower glycolytic enzyme activities in their adductor muscle than larger scallops. This corresponds to the ontogenetic change in susceptibility to predation and in habitat use observed in C. islandica.

Impairment of metabolic capacities in copper and cadmium contaminated wild yellow perch ( Perca flavescens)

This study examined variations in resting oxygen consumption rate (ROCR), post-exercise oxygen consumption rate, relative scope for activity (RSA), liver and muscle aerobic and anaerobic capacities (using citrate synthase (CS) and lactate dehydrogenase, respectively, as indicators), and tissue biosynthetic capacities (using nucleoside diphosphate kinase (NDPK) as an indicator), in wild yellow perch from four lakes varying in copper (Cu) and cadmium (Cd) contamination. Liver Cu and Cd concentrations largely reflected environmental contamination and were positively correlated with liver protein concentrations and NDPK activities. Our results suggest that metal contamination leads to an upregulation of liver protein metabolism, presumably at least in part for the purpose of metal detoxification. In contrast, muscle NDPK activities decreased with increasing liver Cd concentrations and NDPK activities. There was a 25% decrease in ROCR for a doubling of liver Cu concentrations and a 42% decrease in RSA for a doubling of liver Cd concentrations in the range studied. Cu contamination was also associated with lower muscle CS activities. Our results support previous findings of impaired aerobic capacities in the muscle of metal-contaminated fish, and demonstrate that this impairment is also reflected in aerobic capacities of whole fish. The evidence presented suggests that mitochondria may be primary targets for inhibition by Cu, and that Cd may reduce gill respiratory capacity. Muscle aerobic and anaerobic capacities were inversely related. This work indicates that metal exposure of wild yellow perch leads to a wide range of disturbances in metabolic capacities.

The physiological response of diploid and triploid brook trout to exhaustive exercise

Using triploidy as an experimental model, we examined whether cell size limits the post-exercise recovery process in fish. Because triploids generally possess larger cells, which could affect many physiological and biochemical processes, we hypothesized that triploids would take longer to recover from exhaustive exercise compared to diploids. To test this, we measured plasma lactate, glucose and osmolality, and white muscle energy stores (glycogen, phosphocreatine and ATP) and lactate before and immediately following exhaustive exercise and during recovery at 2 and 4 h post-exercise. In addition, oxygen consumption and ammonia excretion rates were determined before and after exhaustive exercise. Overall, diploid and triploid brook trout showed similar metabolic responses exercise, but plasma osmolality, white muscle lactate, white muscle ATP and post-exercise oxygen consumption rates recovered earlier in triploids compared to diploids. The results of this study suggest that the characteristic larger cell size of triploidy does not limit the physiological response to, or recovery from, exhaustive exercise.

Metabolic Responses of Juvenile Striped Bass to Exercise and Handling Stress with Various Recovery Environments

Abstract Striped bass Morone saxatilis were exposed to exercise and handling stresses similar to those experienced during salvage operations in the Sacramento-San Joaquin Delta, California, and several recovery environments to assess energetic costs and mortality. Young of the year (2.1-15.9 g wet weight) were exercised in a swim tunnel at a maximum speed of 94 cm/s (11.7-14.1 body lengths/s) for 5 min at 15°C and 25°C and yearlings (30.8-144.7 g) at the same maximum speed (5.5 body lengths/s) and for the same amount of time at 15°C. Using static respirometry, the preexercise and handling (in freshwater), 0-h postexercise and handling, and 2-h postexercise and handling oxygen consumption rates (mg/h) were measured in four recovery treatments: freshwater, brackish water (10‰ NaCl), salt water (30‰ NaCl), and buffered freshwater (10 mM NaHCO3). Significant increases in 0-h postexercise oxygen consumption rates (compared with the preexercise rates) were followed by significant decreases during recovery, but ...

Juvenile sturgeon exhibit reduced physiological responses to exercise.

Experiments were conducted to determine the physiological responses to exercise of Atlantic sturgeon (Acipenser oxyrhynchus) and shortnose sturgeon (A. brevirostrum). We measured the rates of oxygen consumption and ammonia excretion in both species and a variety of physiological parameters in both muscle (e.g. lactate, glycogen, pyruvate, glucose and phosphocreatine concentrations) and blood (e.g. osmolality and lactate concentration) in juvenile shortnose sturgeon following 5 min of exhaustive exercise. In both species, oxygen consumption and ammonia excretion rates increased approximately twofold following exhaustive exercise. Post-exercise oxygen consumption rates decreased to control levels within 30 min in both sturgeon species, but post-exercise ammonia excretion rates remained high in Atlantic sturgeon throughout the 4 h experiment. Resting muscle energy metabolite levels in shortnose sturgeon were similar to those of other fish species, but the levels decreased only slightly following the exercise period and recovery occurred within an hour. Under resting conditions, muscle lactate levels were low (<1 micromol g(-1)) but they increased to approximately 6 micromol g(-1) after exercise, returning to control levels within 6 h. Unlike similarly stressed teleost fish, such as the rainbow trout, plasma lactate levels did not increase substantially and returned to resting levels within 2 h. Plasma osmolality was not significantly affected by exercise in shortnose sturgeon. Taken together, these results suggest that shortnose and Atlantic sturgeon do not exhibit the physiological responses to exhaustive exercise typical of other fish species. They may possess behavioural or endocrinological mechanisms that differ from those of other fishes and that lead to a reduced ability to respond physiologically to exhaustive exercise.

Post-exercise metabolic rate in Atlantic cod and its dependence upon the method of exhaustion

This study tests whether or not post-exercise oxygen consumption rates (Mo2) in fish are dependent upon how exhaustion is induced. A group of eight Atlantic cod (Gadus morhua) were each exercised using (1) a critical swimming speed (Ucrit) protocol, (2) an exercise protocol designed to measure anaerobic capacity of fish (Uburst), and (3) a protocol in which the fish were chased to exhaustion manually. Mo2 was measured for a 2-h period following exhaustion induced by all three exercise regimes (Ucrit, Uburst and chase). Post-exercise Mo2 following exhaustion from the Uburst and chase protocols were significantly higher than post-exercise Mo2 following the Ucrit protocol. Each fish during the Ucrit protocol exhibited maximal Mo2 during exercise rather than during recovery, yet 75% of the fish during Ubrust recovery and 100% during chase recovery exhibited Mo2 higher than that measured during Ucrit exercise. These results, as well as the large interindividual variations in Mo2 among the eight fish, show that post-exhaustion Mo2 is specific to the exercise regime employed, thus, investigators must exercise caution when combining results from different exercise protocols and/or individuals.