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Sensors (Basel, Switzerland) Aug 2023The purpose of this study was two-fold: (1) to determine the sensitivity of the sEMG shorts-derived training load (sEMG-TL) during different running speeds; and (2) to...
The purpose of this study was two-fold: (1) to determine the sensitivity of the sEMG shorts-derived training load (sEMG-TL) during different running speeds; and (2) to investigate the relationship between the oxygen consumption, heart rate (HR), rating of perceived exertion (RPE), accelerometry-based PlayerLoad (PL), and sEMG-TL during a running maximum oxygen uptake (V˙O) test. The study investigated ten healthy participants. On day one, participants performed a three-speed treadmill test at 8, 10, and 12 km·h for 2 min at each speed. On day two, participants performed a V˙O test. Analysis of variance found significant differences in sEMG-TL at all three speeds ( < 0.05). A significantly weak positive relationship between sEMG-TL and %V˙O ( = 0.31, < 0.05) was established, while significantly strong relationships for 8 out of 10 participants at the individual level ( = 0.72-0.97, < 0.05) were found. Meanwhile, the accelerometry PL was not significantly related to %V˙O ( > 0.05) and only demonstrated significant correlations in 3 out of 10 participants at the individual level. Therefore, the sEMG shorts-derived training load was sensitive in detecting a work rate difference of at least 2 km·h. sEMG-TL may be an acceptable metric for the measurement of internal loads and could potentially be used as a surrogate for oxygen consumption.
Topics: Humans; Exercise Test; Physical Exertion; Oxygen Consumption; Oxygen; Running; Heart Rate
PubMed: 37571780
DOI: 10.3390/s23156998 -
Frontiers in Sports and Active Living 2024One of the main objectives of practicing indoor cardiovascular exercise is to maximize caloric expenditure. This study aimed to compare energy expenditure (EE), oxygen...
OBJECTIVE
One of the main objectives of practicing indoor cardiovascular exercise is to maximize caloric expenditure. This study aimed to compare energy expenditure (EE), oxygen consumption (VO2), and heart rate (HR) recorded in middle-aged adults while exercising on seven different indoor cardiovascular machines at self-selected maximal and submaximal intensity.
METHOD
Thirty recreational-active adult males (Age: 41.69 ± 4.64) performed 12-min bouts at RPE (Rate of perceived exertion) 17 and maximum intensity (MAX INT) on the following indoor cardio machines: Recumbent bike (r_BIKE), upright bike (u-BIKE), spin bike (s-BIKE), rowing machine (ROW), elliptical trainer (ELLIP), stair climber (STAIR), and treadmill (TMILL). Heart rate (HR) and oxygen consumption (VO2) were measured during exercise, whereas EE (energy expenditure) was calculated indirectly.
RESULTS
Overall, TMILL induced the highest levels of EE, VO2, and HR, followed by STAIR, ELLIP, s_BIKE, u_BIKE, ROW, and r_BIKE. RPE was reliable across exercise modalities (r_BIKE, u-BIKE, s-BIKE, ROW, ELLIP, STAIR, and TMILL) and intensities (RPE 17 and MAX INT) for EE, HR, and VO2 measurements.
CONCLUSION
To maximize EE while performing indoor cardiovascular exercise for recreational active middle-aged male participants, the TMILL is the best option, followed by the STAIR and the ELLIP. The least recommended options are, respectively, s_BIKE, u_BIKE, ROW, and r_BIKE. Beyond caloric expenditure considerations, promoting exercises that participants genuinely enjoy can enhance adherence, fostering sustained health benefits. Furthermore, RPE is a reliable tool for assessing EE, VO2, and HR across different exercise modalities and intensities.
PubMed: 38390229
DOI: 10.3389/fspor.2024.1313886 -
Journal of Functional Morphology and... Apr 2024The aim of this study was to verify the accuracy of predicting oxygen consumption (O) in predominantly aerobic activities based on net heart rate (netHR), sex, and body...
The aim of this study was to verify the accuracy of predicting oxygen consumption (O) in predominantly aerobic activities based on net heart rate (netHR), sex, and body mass index (BMI) in active adults. NetHR is the value of the difference between the resting HR (HR) and the average HR value obtained during a given session or period of physical activity. These activities must be continuous, submaximal, and of a stabilized intensity. The magnitude of the netHR depends mainly on the intensity of the exercise. The HR is measured in beats per minute (bpm). A total of 156 participants, 52 women and 104 men, between the ages of 18 and 81, had their netHR and net oxygen intake (netVO) assessed. There were 79 participants in group 1 (prediction sample) (52 males and 27 females). There were 77 people in group 2 (validation sample) (52 males and 25 females). The results of the multiple linear regression showed that netVO (R = 85.2%, SEE = 3.38) could be significantly predicted by sex ( < 0.001), netHR ( < 0.001), and BMI ( < 0.001). The Bland-Altman plots satisfied the agreement requirements, and the comparison of the measured and estimated netVO revealed non-significant differences with a trivial effect size. We calculated the formula NetVO (mL/(kg·min)) = 16 + 3.67 (sex) + 0.27 (netHR) - 0.57 (BMI) to predict netVO, where netVO is the amount of oxygen uptake (mL/(kg·min)) above the resting value, netHR is the heart rate (beats per minute) above the resting value measured during exercise, sex is equal to zero for women and one for men, and BMI is the body mass index. In addition, based on the knowledge of VO, it was possible to estimate the energy expenditure from a particular training session, and to determine or prescribe the exercise intensity in MET (metabolic equivalent of task).
PubMed: 38651424
DOI: 10.3390/jfmk9020066 -
Tumor hypoxia and radiotherapy: A major driver of resistance even for novel radiotherapy modalities.Seminars in Cancer Biology Jan 2024Hypoxia in solid tumors is an important predictor of poor clinical outcome to radiotherapy. Both physicochemical and biological processes contribute to a reduced... (Review)
Review
Hypoxia in solid tumors is an important predictor of poor clinical outcome to radiotherapy. Both physicochemical and biological processes contribute to a reduced sensitivity of hypoxic tumor cells to ionizing radiation and hypoxia-related treatment resistances. A conventional low-dose fractionated radiotherapy regimen exploits iterative reoxygenation in between the individual fractions, nevertheless tumor hypoxia still remains a major hurdle for successful treatment outcome. The technological advances achieved in image guidance and highly conformal dose delivery make it nowadays possible to prescribe larger doses to the tumor as part of single high-dose or hypofractionated radiotherapy, while keeping an acceptable level of normal tissue complication in the co-irradiated organs at risk. However, we insufficiently understand the impact of tumor hypoxia to single high-doses of RT and hypofractionated RT. So-called FLASH radiotherapy, which delivers ionizing radiation at ultrahigh dose rates (> 40 Gy/sec), has recently emerged as an important breakthrough in the radiotherapy field to reduce normal tissue toxicity compared to irradiation at conventional dose rates (few Gy/min). Not surprisingly, oxygen consumption and tumor hypoxia also seem to play an intriguing role for FLASH radiotherapy. Here we will discuss the role of tumor hypoxia for radiotherapy in general and in the context of novel radiotherapy treatment approaches.
Topics: Humans; Tumor Hypoxia; Neoplasms; Radiation Dose Hypofractionation; Hypoxia; Treatment Outcome
PubMed: 38040401
DOI: 10.1016/j.semcancer.2023.11.006 -
Biology Nov 2023Alkylphospholipids (APLs) have been studied as anticancer drugs that interfere with biological membranes without targeting DNA. Although their mechanism of action is not...
Alkylphospholipids (APLs) have been studied as anticancer drugs that interfere with biological membranes without targeting DNA. Although their mechanism of action is not fully elucidated yet, it is known that they disrupt the intracellular trafficking of cholesterol and its metabolism. Here, we analyzed whether APLs could also interfere with mitochondrial function. For this purpose, we used HT29 colorectal cancer cells, derived from a primary tumor, and SW620 colorectal cancer cells, derived from a metastasis site. After treatment with the APLs miltefosine and perifosine, we analyzed various mitochondrial parameters, including mitochondrial mass, cardiolipin content, mitochondrial membrane potential, HO production, the levels of oxidative phosphorylation (OXPHOS) complexes, metabolic enzymes activity, the oxygen consumption rate, and the levels of apoptosis and autophagy markers. APLs, especially perifosine, increased mitochondrial mass while OXPHOS complexes levels were decreased without affecting the total oxygen consumption rate. Additionally, we observed an increase in pyruvate dehydrogenase (PDH) and isocitrate dehydrogenase (IDH) levels and a decrease in lactate dehydrogenase (LDH) activity, suggesting a metabolic rewiring induced by perifosine. These alterations led to higher mitochondrial membrane potential, which was potentiated by decreased uncoupling protein 2 (UCP2) levels and increased reactive oxygen species (ROS) production. Consequently, perifosine induced an imbalance in mitochondrial function, resulting in higher ROS production that ultimately impacted cellular viability.
PubMed: 38132283
DOI: 10.3390/biology12121457 -
Frontiers in Physiology 2023Red blood cells (RBCs) undergo metabolic, oxidative, and physiological changes during storage, collectively described as the "storage lesion." The impact of storage on...
Changes in hemoglobin oxidation and band 3 during blood storage impact oxygen sensing and mitochondrial bioenergetic pathways in the human pulmonary arterial endothelial cell model.
Red blood cells (RBCs) undergo metabolic, oxidative, and physiological changes during storage, collectively described as the "storage lesion." The impact of storage on oxygen homeostasis, following transfusion, is not fully understood. We show that RBC storage induces changes in oxygen binding that were linked to changes in oxygen sensing (hypoxia-inducible factor, HIF-1α) mechanisms and mitochondrial respiration in human pulmonary arterial endothelial cells (HPAECs). A decrease in oxygen affinity (P) to approximately 20 from 30 mmHg was seen at the first week but remained unchanged for up to 42 days. This led to the suppression of HIF-1α in the first 3 weeks due to limited oxygen supplies by RBCs. Furthermore, membrane oxidative damage, band 3 alterations, and subsequent microparticle (MP) formation were also noted. Mass spectrometric analysis revealed the upregulation of transitional endoplasmic reticulum ATPase, essential for clearing ROS-damaged membrane proteins and the protein DDI1 homolog, a proteasomal shuttle chaperone. Band 3 complex proteins and superoxide dismutase were among the downregulated proteins. Mitochondrial oxygen consumption rates measured in HPAECs incubated with RBC-derived MPs (14-day and 42-day) showed a rise in maximal respiration. Intervention strategies that target intracellular hemoglobin (Hb)'s redox transitions and membrane changes may lead to the reestablishment of oxygen homeostasis in old RBCs.
PubMed: 37916221
DOI: 10.3389/fphys.2023.1278763 -
European Journal of Sport Science Aug 2023This study aimed to assess if, during incremental exercise, considering individual characteristics can make the relationship between the percentages of heart rate (HRR)...
This study aimed to assess if, during incremental exercise, considering individual characteristics can make the relationship between the percentages of heart rate (HRR) and oxygen uptake (OR) reserve either 1:1 or more accurate. Cycle ergometer data of the maximal incremental exercise tests performed by 450 healthy and sedentary participants (17-66 years) of the HERITAGE Family Study, grouped for sex, ethnicity, age, body fat, resting HR, and O, were used to calculate the individual linear regressions between %HRR and %OR. The mean slope and intercept of the individual linear regressions of each subgroup were compared with 1 and 0 (identity line), respectively, using Hotelling tests followed by post-hoc one-sample -tests. Two multiple linear regressions were also performed, using either the slopes or intercepts of the individual linear regressions as dependent variables and sex, age, resting HR, and O as independent variables. The mean %HRR-%OR relationships of all subgroups differed from the identity line. Moreover, individual linear regression intercepts (8.9 ± 16.0) and slopes (0.971 ± 0.190) changed (< 0.001) after 20 weeks of aerobic training (13.1 ± 11.1 and 0.891 ± 0.122). The multiple linear regressions could explain only 3.8% and 1.3% of the variance in the intercepts and slopes, whose variability remained high (standard error of estimate of 15.8 and 0.189). In conclusion, the %HRR-%OR relationship differs from the identity line regardless of individual characteristics and their difference increased after aerobic training. Moreover, due to the high interindividual variability, using a single equation for the whole population seems not suitable for representing the %HRR-%OR relationship of a given subject, even when several individual characteristics are considered.The association between %HRR and %OR is not 1:1 even when individuals are grouped by age, sex, ethnicity, body composition, HR, and O.Using several subject characteristics to identify the individual's %HRR-%OR relationship does not meaningfully increase its prediction accuracy or reduce the interindividual variability of %HRR-%OR relationshipsUsing a single equation for the whole population is not suitable for representing the relationship of a given subject; hence, individual relationships should be preferred when prescribing the intensity of aerobic exercise.The individual %HRR-%OR relationship should be periodically assessed due to the potential training induced changes in the relationship.
Topics: Humans; Oxygen Consumption; Heart Rate; Exercise; Exercise Test; Ergometry
PubMed: 35960537
DOI: 10.1080/17461391.2022.2113441 -
The Korean Journal of Physiology &... May 2024In addition to cellular damage, ischemia-reperfusion (IR) injury induces substantial damage to the mitochondria and endoplasmic reticulum. In this study, we sought to...
In addition to cellular damage, ischemia-reperfusion (IR) injury induces substantial damage to the mitochondria and endoplasmic reticulum. In this study, we sought to determine whether impaired mitochondrial function owing to IR could be restored by transplanting mitochondria into the heart under ex vivo IR states. Additionally, we aimed to provide preliminary results to inform therapeutic options for ischemic heart disease (IHD). Healthy mitochondria isolated from autologous gluteus maximus muscle were transplanted into the hearts of Sprague-Dawley rats damaged by IR using the Langendorff system, and the heart rate and oxygen consumption capacity of the mitochondria were measured to confirm whether heart function was restored. In addition, relative expression levels were measured to identify the genes related to IR injury. Mitochondrial oxygen consumption capacity was found to be lower in the IR group than in the group that underwent mitochondrial transplantation after IR injury (p < 0.05), and the control group showed a tendency toward increased oxygen consumption capacity compared with the IR group. Among the genes related to fatty acid metabolism, (p < 0.05) and (p < 0.01) showed significant expression in the following order: IR group, IR + transplantation group, and control group. These results suggest that mitochondrial transplantation protects the heart from IR damage and may be feasible as a therapeutic option for IHD.
PubMed: 38682169
DOI: 10.4196/kjpp.2024.28.3.209 -
Italian Journal of Pediatrics Sep 2023Coronary artery (CA) Z-score system is widely used to define CA aneurysm (CAA). Children and adolescents after acute stage of Kawasaki disease (KD-CA) have a higher risk...
When two Z-scores meet-analysis of exercise capacity of children and adolescents with Kawasaki disease by a new Z-score model of coronary artery and a new Z-score evaluating peak oxygen consumption : Coronary artery Z-score and peakVO2 Z-score in KD.
BACKGROUND
Coronary artery (CA) Z-score system is widely used to define CA aneurysm (CAA). Children and adolescents after acute stage of Kawasaki disease (KD-CA) have a higher risk of developing CAAs if their CA Z-score ≥ 2.5. Z-score system of peak oxygen consumption (Peak VO Z-score) allows comparisons across ages and sex, regardless of body size and puberty. We aimed to compare the exercise capacity (EC) indicated by peak VO Z-score during cardiopulmonary exercise testing (CPET) directly between KD-CA with different CA Z-score.
METHODS
KD-CA after acute stage who received CPET in the last 5 years were retrospectively recruited. CA Z-score was based on Lambda-Mu-Sigma method. Max-Z was the maximum CA Z-score of different CAs. KD children with Max-Z < 2.5 and ≥ 2.5 were defined as KD-1 and KD-2 groups, respectively. Peak VO Z-score was calculated using the equation established based on Hong Kong Chinese children and adolescent database.
RESULTS
One hundred two KD-CA were recruited (mean age: 11.71 ± 2.57 years). The mean percent of measured peak VO to predicted value (peak PD%) was 90.11 ± 13.33. All basic characteristics and baseline pulmonary function indices were comparable between KD-1 (n = 87) and KD-2 (n = 15). KD-1 had significantly higher peak VO Z-score (p = .025), peak PD% (p = .008), peak metabolic equivalent (p = .027), and peak rate pressure product (p = .036) than KD-2.
CONCLUSIONS
KD-CA had slightly reduced EC than healthy peers. KD-CA with Max-Z ≥ 2.5 had significantly lower peak EC than those < 2.5. Max-Z is potentially useful follow-up indicator after acute stage of KD.
Topics: Humans; Child; Adolescent; Mucocutaneous Lymph Node Syndrome; Coronary Vessels; Retrospective Studies; Exercise Tolerance; Oxygen Consumption
PubMed: 37773131
DOI: 10.1186/s13052-023-01535-3 -
European Journal of Sport Science Aug 2023Walking or balancing on a slackline has gained increasing popularity as a recreational and school sport, and has been found to be suitable for developing neuromuscular...
Walking or balancing on a slackline has gained increasing popularity as a recreational and school sport, and has been found to be suitable for developing neuromuscular control. The metabolic requirements for neuromuscular control on slackline, however, have not been well described. Therefore, the aim of the study was to determine the metabolic demands of slacklining in less and more advanced slackliners. Nineteen slackliners performed several 4 min balance tasks: parallel and one-leg stance on stable platform (2LS and 1LS), 1 leg stance on a slackline (1LSS), walking at a self-selected speed and at a given speed of 15 m min on a slackline (WSS and WGS). Expired gas samples were collected for all participants and activities using a portable metabolic system. During1 LS and 1LSS, there were 140% and 341% increases in oxygen uptake (O) with respect to O rest, respectively. During slackline walking, O increased by 460% and 444% at self-selected and given speed, respectively. More advanced slackliners required mean metabolic demands 0.377 ± 0.065 and 0.289 ± 0.050 kJ·kg·min (5.7 ± 0.95 and 3.9 ± 0.6 MET) for WGS and 1LSS, respectively, whilst less advanced slackliners, 0.471 ± 0.081 and 0.367 ± 0.086 kJ·kg·min (6.4 ± 1.2 and 5.0 ± 1.1 MET) for WGS and 1LSS, respectively. Our data suggest that balancing tasks on slackline require O corresponding to exercise intensities from light to moderate intensity. More advanced slackliners had a ∼25% reduced energy expenditure when compared with lower ability counterparts during simple balance tasks on the slackline.Balancing on a slackline is metabolically demanding and slackline training is suitable not only to develop neuromuscular control but also to meet cardiovascular fitness demands.Improved postural control demonstrated by skilled slackliners reduces by ∼25% metabolic cost of balancing tasks on a slackline when compared to less skilled counterparts.Falls during slacklining increase the metabolic demands of the activity. Three falls per minute during walking on a slackline increase the oxygen uptake by ∼50%.
Topics: Humans; Physical Conditioning, Human; Sports; Exercise; Walking; Oxygen; Energy Metabolism; Oxygen Consumption
PubMed: 36994663
DOI: 10.1080/17461391.2023.2196666