Stability of carboxy-hemoglobin during storage at different temperatures.

Accurate determination of carboxy-hemoglobin (COHb%) is essential for the assessment of hemoglobin mass (Hbmass) by CO-rebreathing. To analyze blood samples for a certain period of time after blood collection, it is necessary to know the stability of the COHb% during storage. The aim of the study was to determine the stability of COHb% at different storage temperatures over a period of up to 3 months. Twenty-five milliliters of cubital venous blood was taken from five volunteers (three females and two males) before and after inhalation of 0.8/1.0 mL/kg carbon monoxide and stored at +20°C and +4°C for 6 days and at -70°C for 12 weeks. Within the first 6 days, the blood was analyzed daily, then weekly for 12 weeks. Additionally, Hbmass was determined in 13 endurance athletes immediately after blood collection and after storage for 3 days (eight cyclists) and 7 days (five swimmers) at +20°C or +4°C. COHb% before and after CO inhalation was 1.56 ± 0.48 and 5.86 ± 1.12%, respectively, and remained unchanged over 6 days, with no difference between storage at different temperatures. The standard deviation (STD) over time was between 0.07% and 0.12%. Similarly, storage at -70°C for 12 weeks did not change COHb%, whereas STD was 0.07%. Hbmass determined immediately and, after 3 or 7 days of storage, differed by 10 ± 7 g and 15 ± 11 g corresponding to a typical error of 0.8% and 1.1%. Blood storage at +20°C and +4°C for 6 days and at -70°C for 12 weeks does not affect COHb% and has, therefore, no influence on Hbmass assessment.

Effect of Fluid Intake on Acute Changes in Plasma Volume: A Randomized Controlled Crossover Pilot Trial.

Plasma volume (PV) undergoes constant and dynamic changes, leading to a large intra-day variability in healthy individuals. Hydration is known to induce PV changes; however, the response to the intake of osmotically different fluids is still not fully understood. In a randomized controlled crossover trial, 18 healthy individuals (10 females) orally received an individual amount of an isotonic sodium-chloride (ISO), Ringer (RIN), or glucose (GLU) solution. Hemoglobin mass (Hbmass) was determined with the optimized carbon monoxide re-breathing method. Fluid-induced changes in PV were subsequently calculated based on capillary hemoglobin concentration ([Hb]) and hematocrit (Hct) before and then every 10 minutes until 120 min (t0-120) after the fluid intake and compared to a control trial arm (CON), where no fluid was administered. Within GLU and CON trial arms, no statistically significant differences from baseline until t120 were found (p > 0.05). In the ISO trial arm, PV was significantly increased at t70 (+138 mL, p = 0.01), t80 (+191 mL, p < 0.01), and t110 (+182 mL, p = 0.01) when compared to t0. Moreover, PV in the ISO trial arm was significantly higher at t70 (p = 0.02), t110 (p = 0.04), and t120 (p = 0.01) when compared to the same time points in the CON trial arm. Within the RIN trial arm, PV was significantly higher between t70 and t90 (+183 mL, p = 0.01) and between t110 (+194 mL, p = 0.03) and t120 (+186 mL, p < 0.01) when compared to t0. These results demonstrated that fluids with a higher content of osmotically active particles lead to acute hemodilution, which is associated with a decrease in [Hb] and Hct. These findings underpin the importance of the hydration state on PV and especially on PV constituent levels in healthy individuals.

Effects of Different Types of Intermittent Fasting Interventions on Metabolic Health in Healthy Individuals (EDIF): A Randomised Trial with a Controlled-Run in Phase.

The effects of intermittent fasting (IF) on health promotion in the healthy population remain controversial. Therefore, our study aimed to analyse the efficacy and feasibility of different IF protocols and evaluated the effects within a cohort with a controlled-run in phase on the body mass index (BMI) as the primary outcome, the body composition, and metabolic and haematological markers in healthy participants. A total of 25 individuals were randomised into three fasting groups: 16/8 fasting (n = 11), 20/4 fasting (n = 6), and alternate-day fasting (ADF, n = 8). Assessments were conducted at baseline (visit 1), after a four-week controlled-run in phase (visit 2), and after eight weeks of fasting (visit 3). Both the BMI (p = 0.01) and bodyweight (p = 0.01) were significantly reduced in the ADF group, which was not seen in the 16/8 and 20/4 groups (p > 0.05). Adherence was different but not statistically among the groups (16/8: 84.5 ± 23.0%; 20/4: 92.7 ± 9.5%; and ADF: 78.1 ± 33.5%, p = 0.57). Based on our obtained results, the data suggest that some fasting interventions might be promising for metabolic health. However, adherence to the specific fasting protocols remains challenging even for the healthy population.

(Hybrid) Closed-Loop Systems: From Announced to Unannounced Exercise.

Physical activity and exercise have many beneficial effects on general and type 1 diabetes (T1D) specific health and are recommended for individuals with T1D. Despite these health benefits, many people with T1D still avoid exercise since glycemic management during physical activity poses substantial glycemic and psychological challenges - which hold particularly true for unannounced exercise when using an AID system. Automated insulin delivery (AID) systems have demonstrated their efficacy in improving overall glycemia and in managing announced exercise in numerous studies. They are proven to increase time in range (70-180 mg/dL) and can especially counteract nocturnal hypoglycemia, even when evening exercise was performed. AID-systems consist of a pump administering insulin as well as a CGM sensor (plus transmitter), both communicating with a control algorithm integrated into a device (insulin pump, mobile phone/smart watch). Nevertheless, without manual pre-exercise adaptions, these systems still face a significant challenge around physical activity. Automatically adapting to the rapidly changing insulin requirements during unannounced exercise and physical activity is still the Achilles' heel of current AID systems. There is an urgent need for improving current AID-systems to safely and automatically maintain glucose management without causing derailments - so that going forward, exercise announcements will not be necessary in the future. Therefore, this narrative literature review aimed to discuss technological strategies to how current AID-systems can be improved in the future and become more proficient in overcoming the hurdle of unannounced exercise. For this purpose, the current state-of-the-art therapy recommendations for AID and exercise as well as novel research approaches are presented along with potential future solutions - in order to rectify their deficiencies in the endeavor to achieve fully automated AID-systems even around unannounced exercise.

Speckle-Tracking Analysis of the Right and Left Heart after Peak Exercise in Healthy Subjects with Type 1 Diabetes: An Explorative Analysis of the AppEx Trial.

In eight healthy participants with Type 1 diabetes (T1D) exercise-related dynamic cardiac remodeling was analyzed by performing two-dimensional echocardiography, including deformation analysis of the left-ventricular (LV) global longitudinal strain (LV-GLS), and the deformation pattern of the left atrium (LA) and right ventricle (RV) at rest and post-peak performance on a bicycle. The feasibility echocardiographic speckle-tracking analysis was performed on eight asymptomatic participants with T1D (n = 8, male n = 5, age: 23-65 years). The obtained echocardiographic data were compared for various echocardiographic parameters at rest and post exercise. Across our participating T1D individuals no structural echocardiographic abnormalities of concern could be revealed. All participating T1D subjects showed preserved contractile reserve of the LV and no significant diastolic dysfunction. Significant differences were found for the phasic LA contractile strain pattern at rest and post exercise (p < 0.001), whereby the dynamic RV (p = 0.5839 and p = 0.7419) and LV strain pattern (p = 0.5952) did not reveal significant differences in comparison to resting conditions. This descriptive secondary outcome analysis describes preserved contractile reserve of the LV and elucidates dynamic modification of the phasic LA contractile deformation pattern in asymptomatic T1D individuals after exhaustive exercise on a bicycle.

Efficacy of Fasting in Type 1 and Type 2 Diabetes Mellitus: A Narrative Review.

Over the last decade, studies suggested that dietary behavior modification, including fasting, can improve metabolic and cardiovascular markers as well as body composition. Given the increasing prevalence of people with type 1 (T1DM) and type 2 diabetes mellitus (T2DM) and the increasing obesity (also in combination with diabetes), nutritional therapies are gaining importance, besides pharmaceutical interventions. Fasting has demonstrated beneficial effects for both healthy individuals and those with metabolic diseases, leading to increased research interest in its impact on glycemia and associated short- and long-term complications. Therefore, this review aimed to investigate whether fasting can be used safely and effectively in addition to medications to support the therapy in T1DM and T2DM. A literature search on fasting and its interaction with diabetes was conducted via PubMed in September 2022. Fasting has the potential to minimize the risk of hypoglycemia in T1DM, lower glycaemic variability, and improve fat metabolism in T1DM and T2DM. It also increases insulin sensitivity, reduces endogenous glucose production in diabetes, lowers body weight, and improves body composition. To conclude, fasting is efficient for therapy management for both people with T1DM and T2DM and can be safely performed, when necessary, with the support of health care professionals.

Relationship between Blood Volume, Blood Lactate Quantity, and Lactate Concentrations during Exercise.

We wanted to determine the influence of total blood volume (BV) and blood lactate quantity on lactate concentrations during incremental exercise. Twenty-six healthy, nonsmoking, heterogeneously trained females (27.5 ± 5.9 ys) performed an incremental cardiopulmonary exercise test on a cycle ergometer during which maximum oxygen uptake (V·O2max), lactate concentrations ([La-]) and hemoglobin concentrations ([Hb]) were determined. Hemoglobin mass and blood volume (BV) were determined using an optimised carbon monoxide-rebreathing method. V·O2max and maximum power (Pmax) ranged between 32 and 62 mL·min-1·kg-1 and 2.3 and 5.5 W·kg-1, respectively. BV ranged between 81 and 121 mL·kg-1 of lean body mass and decreased by 280 ± 115 mL (5.7%, p = 0.001) until Pmax. At Pmax, the [La-] was significantly correlated to the systemic lactate quantity (La-, r = 0.84, p < 0.0001) but also significantly negatively correlated to the BV (r = -0.44, p < 0.05). We calculated that the exercise-induced BV shifts significantly reduced the lactate transport capacity by 10.8% (p < 0.0001). Our results demonstrate that both the total BV and La- have a major influence on the resulting [La-] during dynamic exercise. Moreover, the blood La- transport capacity might be significantly reduced by the shift in plasma volume. We conclude, that the total BV might be another relevant factor in the interpretation of [La-] during a cardio-pulmonary exercise test.

The effect of posture and exercise on blood CO kinetics during the optimized carbon monoxide rebreathing procedure.

An indispensable precondition for the determination of hemoglobin mass (Hbmass) and blood volume by CO rebreathing is complete mixing of CO in the blood. The aim of this study was to demonstrate the kinetics of CO in capillary and venous blood in different body positions and during moderate exercise. Six young subjects (4 male, 2 female) performed three 2-min CO rebreathing tests in seated (SEA) & supine (SUP) positions as well as during moderate exercise (EX) on a bicycle ergometer. Before, during, and until 15 min after CO rebreathing cubital venous and capillary blood samples were collected simultaneously and COHb% was determined. COHb% kinetics were significantly slower in SEA than in SUP or EX. Identical COHb% in capillary and venous blood were reached in SEA after 5.0 ± 2.3 min, in SUP after 3.2 ± 1.3 min and in EX after 1.9 ± 1.2 min (EX vs. SEA p < .01, SUP vs. SEA p < .05). After 7th min, Hbmass did not differ between the resting positions (capillary: SEA 766 ± 217 g, SUP 761 ± 227 g; venous: SEA 759 ± 224 g, SUP 744 ± 207 g). Under exercise, however, a higher Hbmass (p < .05) was determined (capillary: 823 ± 221 g, venous: 804 ± 226 g). In blood, the CO mixing time in the supine position is significantly shorter than in the seated position. By the 6th minute complete mixing is achieved in either position giving similar Hbmass determinations. CO-rebreathing under exercise conditions, however, leads to ∼7% higher Hbmass values.

Acute Fluid Intake Impacts Assessment of Body Composition via Bioelectrical Impedance Analysis. A Randomized, Controlled Crossover Pilot Trial.

Bioelectrical impedance analysis (BIA) has proven to be particularly useful due to its inexpensive and rapid assessment of total body water and body density. However, recent fluid intake may confound BIA results since equilibration of fluid between intra- and extracellular spaces may take several hours and furthermore, ingested fluids may not be fully absorbed. Therefore, we aimed to evaluate the impact of different fluid compositions on the BIA. A total of eighteen healthy individuals (10 females, mean ± SD age of 23.1 ± 1.8 years) performed a baseline measurement of body composition before they consumed isotonic 0.9% sodium-chloride (ISO), 5% glucose (GLU) or Ringer (RIN) solutions. During the visit of the control arm (CON), no fluid was consumed. Further impedance analyses were conducted every 10 min after the fluid consumption for 120 min. We found statistically significant interactions between the effects of solution ingestion and time for intra- (ICW, p < 0.01) and extracellular water (ECW, p < 0.0001), skeletal muscle mass (SMM, p < 0.001) and body fat mass (FM, p < 0.01), respectively. Simple main effects analysis showed that time had a statistically significant effect on changes in ICW (p < 0.01), ECW (p < 0.01), SMM (p < 0.01) and FM (p < 0.01), while fluid intake did not have a significant effect. Our results highlight the importance of a standardized pre-measurement nutrition, with particular attention to hydration status when using a BIA for the evaluation of body composition.

Possible strategies to reduce altitude-related excessive polycythemia.

We sought to determine the effects of three treatments on hemoglobin (Hb) levels in patients with chronic mountain sickness (CMS): 1) descent to lower altitude, 2) nocturnal O2 supply, 3) administration of acetazolamide. Nineteen patients with CMS living at an altitude of 3,940 ± 130 m participated in the study, which consisted of a 3-wk intervention phase and a 4-wk postintervention phase. Six patients spent 3 wk at an altitude of 1,050 m (low altitude group, LAG), six received supplemental oxygen for 12 h overnight (oxygen group, OXG), and seven received 250 mg of acetazolamide daily (acetazolamide group, ACZG). Hemoglobin mass (Hbmass) was determined using an adapted carbon monoxide (CO) rebreathing method before, weekly during, and 4 wk postintervention. Hbmass decreased by 245 ± 116 g (P < 0.01) in the LAG and by 100 ± 38 g in OXG, and 99 ± 64 g in ACZG (P < 0.05, each), respectively. In LAG, hemoglobin concentration ([Hb]) decreased by 2.1 ± 0.8 g/dL and hematocrit by 7.4 ± 2.9% (both P < 0.01), whereas OXG and ACZG only trended toward lower values. Erythropoietin concentration ([EPO]) decreased between 81 ± 12% and 73 ± 21% in LAG at low altitude (P < 0.01) and increased by 161 ± 118% 5 days after return (P < 0.01). In OXG and ACZG, the [EPO] decrease was ∼75% and ∼50%, respectively, during the intervention (P < 0.01). Descent to low altitude (from 3,940 m to 1,050 m) is a fast-acting measure for the treatment of excessive erythrocytosis in patients with CMS, reducing Hbmass by 16% within 3 wk. Nighttime oxygen supplementation and daily acetazolamide administration are also effective, but reduce Hbmass by only 6%.NEW & NOTEWORTHY To our knowledge, this is the first study examining the effect of three different treatments [descending to lower altitude (from 3,900 m to 1,050 m), nocturnal oxygen supply, and administration of acetazolamide] on changes in hemoglobin mass in patients experiencing chronic mountain sickness (CMS). We report that descent to low altitude is a fast-acting measure for the treatment of excessive erythrocytosis in patients with CMS, reducing Hbmass by 16% within 3 wk. Nighttime oxygen supplementation and daily acetazolamide administration are also effective, but reduce Hbmass by only 6%. In all three treatments, the underlying mechanism is a reduction in plasma erythropoietin concentration due to higher oxygen availability.

Effects of Different Fasting Interventions on Cardiac Autonomic Modulation in Healthy Individuals: A Secondary Outcome Analysis of the EDIF Trial.

The impact of a fasting intervention on electrocardiographic (ECG) time intervals and heart rate variability (HRV) is a focus that is scarcely analyzed. The main focus of these secondary outcome data was to describe the impact of a different fasting intervention on ECG and HRV analyses. Twenty-seven healthy individuals participated in this study (11 females, aged 26.3 ± 3.8 years, BMI 24.7 ± 3.4 kg/m2), including a pre-intervention controlled run-in period. Participants were randomized to one of the three fasting cohorts: (I) alternate day fasting (ADF, n = 8), (II) 16/8 fasting (16/8 h of fasting/feasting, n = 11) and (III) 20/4 fasting (20/4 h of fasting/feasting, n = 8). An analysis of baseline ECG parameters and HRV parameters following different fasting interventions demonstrated the safety of these interventions without impacting on heart rate variability parameters during Schellong-1 testing, and revealed comparable preserved autonomic cardiac modulation (ACM) independently of the fasting intervention. In conclusion, different short-term fasting interventions demonstrated no safety ECG-based concerns and showed comparable ACM based on ECG and HRV assessments. Finally, our research topic might strengthen the scientific knowledge of intermittent fasting strategies and indicate potential clinically preventive approaches with respect to occurring metabolic disease and obesity in healthy young subjects.

Glucose and Fructose Supplementation and Their Acute Effects on Anaerobic Endurance and Resistance Exercise Performance in Healthy Individuals: A Double-Blind Randomized Placebo-Controlled Crossover Trial.

BACKGROUND: The effects of glucose, fructose and a combination of these on physical performance have been subject of investigation, resulting in diverse findings. OBJECTIVE: The aim of this study was to investigate how an individualized amount of glucose, fructose, and a combination of these compared to placebo (sucralose) alter endurance performance on a cycle ergometer, lower and upper body resistance exercise performance at individualized thresholds in healthy young individuals. METHODS: A total of 16 healthy adults (9 females) with an age of 23.8 ± 1.6 years and a BMI of 22.6 ± 1.8 kg/m2 (body mass (BM) 70.9 ± 10.8 kg, height 1.76 ± 0.08 m) participated in this study. During the screening visit, the lactate turn point 2 (LTP2) was defined and the weights for chest-press and leg-press were determined. Furthermore, 30 min prior to each exercise session, participants received either 1 g/kg BM of glucose (Glu), 1 g/kg BM of fructose (Fru), 0.5 g/kg BM of glucose/fructose (GluFru) (each), or 0.2 g sucralose (placebo), respectively, which were dissolved in 300 mL of water. All exercises were performed until volitional exhaustion. Time until exhaustion (TTE) and cardio-pulmonary variables were determined for all cycling visits; during resistance exercise, repetitions until muscular failure were counted and time was measured. During all visits, capillary blood glucose and blood lactate concentrations as well as venous insulin levels were measured. RESULTS: TTE in cycling was 449 ± 163 s (s) (Glu), 443 ± 156 s (Fru), 429 ± 160 s (GluFru) and 466 ± 162 s (Pla) (p = 0.48). TTE during chest-press sessions was 180 ± 95 s (Glu), 180 ± 92 s (Fru), 172 ± 78 s (GluFru) and 162 ± 66 s (Pla) (p = 0.25), respectively. CONCLUSIONS: Pre-exercise supplementation of Glu, Fru and a combination of these did not have an ergogenic effect on high-intensity anaerobic endurance performance and on upper and lower body moderate resistance exercise in comparison to placebo.

Cardiac stroke volume in females and its correlation to blood volume and cardiac dimensions.

We aimed to continuously determine the stroke volume (SV) and blood volume (BV) during incremental exercise to evaluate the individual SV course and to correlate both variables across different exercise intensities. Twenty-six females with heterogeneous endurance capacities performed an incremental cycle ergometer test to continuously determine the oxygen uptake (V̇O2), cardiac output (Q̇) and changes in BV. Q̇ was determined by impedance cardiography and resting cardiac dimensions by 2D echocardiography. Hemoglobin mass and BV were determined using a carbon monoxide-rebreathing method. V̇O2max ranged from 32 to 62 mL·kg-1·min-1. Q̇max and SVmax ranged from 16.4 to 31.6 L·min-1 and 90-170 mL, respectively. The SV significantly increased from rest to 40% and from 40% to 80% V̇O2max. Changes in SV from rest to 40% V̇O2max were negatively (r = -0.40, p = 0.05), between 40% and 80% positively correlated with BV (r = 0.45, p < 0.05). At each exercise intensity, the SV was significantly correlated with the BV and the cardiac dimensions, i.e., left ventricular muscle mass (LVMM) and end-diastolic diameter (LVEDD). The BV decreased by 280 ± 115 mL (5.7%, p = 0.001) until maximum exercise. We found no correlation between the changes in BV and the changes in SV between each exercise intensity. The hemoglobin concentration [Hb] increased by 0.8 ± 0.3 g·dL-1, the capillary oxygen saturation (ScO2) decreased by 4.0% (p < 0.001). As a result, the calculated arterial oxygen content significantly increased (18.5 ± 1.0 vs. 18.9 ± 1.0 mL·dL-1, p = 0.001). A 1 L higher BV at V̇O2max was associated with a higher SVmax of 16.2 mL (r = 0.63, p < 0.001) and Q̇max of 2.5 L·min-1 (r = 0.56, p < 0.01). In conclusion, the SV strongly correlates with the cardiac dimensions, which might be the result of adaptations to an increased volume load. The positive effect of a high BV on SV is particularly noticeable at high and severe intensity exercise. The theoretically expected reduction in V̇O2max due to lower SV as a consequence of reduced BV is apparently compensated by the increased arterial oxygen content due to a higher [Hb].

Glucose and Fructose Supplementation and Their Acute Effects on Electrocardiographic Time Intervals during Anaerobic Cycling Exercise in Healthy Individuals: A Secondary Outcome Analysis of a Double-Blind Randomized Crossover-Controlled Trial.

The impact of glucose and fructose supplementation on acute cardiac effects during cardiopulmonary exercise testing (CPET) is a topic that is rarely investigated. The aim of the presented secondary outcome analysis of a double-blind, randomized crossover-controlled trial was to investigate the impact of glucose (Glu), fructose (Fru), glucose and fructose (GluFru), and sucralose on electrocardiogram (ECG), heart rate variability (HRV), premature ventricular complexes (PVCs), and heart rate turn points (HRTP) during CPET. Fourteen healthy individuals (age 25.4 ± 2.5 years, body mass index (BMI) 23.7 ± 1.7 kg/m2, body mass (BM) of 76.3 ± 12.3 kg) participated in this study, of which 12 were included for analysis. Participants received 1 g/kg BM of Glu, 1 g/kg BM of Fru, 0.5 g/kg BM of GluFru (each), and 0.2 g sucralose dissolved in 300 mL 30 min prior to each exercise session. No relevant clinical pathology or significant inter-individual differences between our participants could be revealed for baseline ECG parameters, such as heart rate (HR) (mean HR 70 ± 16 bpm), PQ interval (146 ± 20 ms), QRS interval (87 ± 16 ms) and the QT (405 ± 39 ms), and QTc interval (431 ± 15 ms). We found preserved cardiac autonomic function by analyzing the acute effects of different Glu, Fru, GluFru, or sucralose supplementation on cardiac autonomic function by Schellong-1 testing. SDNN and RMSSD revealed normal sympathetic and parasympathetic activities displaying a balanced system of cardiac autonomic regulation across our participating subjects with no impact on the metabolism. During CPET performance analyses, HRV values did not indicate significant changes between the ingested drinks within the different time points. Comparing the HRTP of the CPET with endurance testing by variable metabolic conditions, no significant differences were found between the HRTP of the CPET data (170 ± 12 bpm), Glu (171 ± 10 bpm), Fru (171 ± 9 bpm), GluFru (172 ± 9 bpm), and sucralose (170 ± 8 bpm) (p = 0.83). Additionally, the obtained time to reach HRTP did not significantly differ between Glu (202 ± 75 s), Fru (190 ± 88 s), GluFru (210 ± 89 s), and sucralose (190 ± 34 s) (p = 0.59). The significance of this study lies in evaluating the varying metabolic conditions on cardiac autonomic modulation in young healthy individuals. In contrast, our participants showed comparable cardiac autonomic responses determined by ECG and CPET.

Hemoglobin Mass and Blood Volume in Patients With Altitude-Related Polycythemia.

Patients with chronic mountain sickness (CMS) have a high hemoglobin concentration [Hb] due to increased hemoglobin mass (Hbmass) and possibly reduced plasma volume (PV). The values of Hbmass, PV and blood volume (BV) have been described differently, and the relationships between [Hb] and Hbmass or PV are poorly understood. This study obtained representative Hbmass, PV and BV data from healthy, high-altitude residents and CMS patients and quantified the dependency of [Hb] on Hbmass and PV. METHODS: Eighty-seven subjects born at high altitude (∼3,900 m) were enrolled. Thirty-four had CMS (CMS), 11 had polycythemia without CMS (intermediate, IM), 20 were healthy highlanders (HH), and 22 living near sea level (SL, 420 m) served as the sea level (SL) control group. Hbmass, PV and BV were determined using a CO-rebreathing method modified for assessing polycythemia patients. Furthermore, [Hb], hematocrit (Hct), plasma erythropoietin concentration [EPO] and blood gas and acid-base status were determined. RESULTS: In the HH group, Hbmass was 27% higher (940 ± 105 g) than in the SL group (740 ± 112 g) and 72% (1,617 ± 265 g) lower than in the CMS group. The PV in the HH group was similar to that in the SL group (-6%) and 15% higher than that in the CMS group (p < 0.001). In the HH group, the BV (5,936 ± 673 ml) did not differ from that in the SL group and was 28% lower than in the CMS group (7,606 ± 1075 ml, p < 0.001). Log [EPO] was slightly increased in the CMS group relative to the HH group (p < 0.01). All values in the IM group were between those in the HH and CMS groups. Hbmass and BV were positively correlated, and PV was negatively correlated with peripheral O2 saturation. Increased Hbmass and decreased PV contributed approximately 65 and 35%, respectively, to the difference in [Hb] between the HH (17.1 ± 0.8 g/dl) and CMS (22.1 ± 1.0 g/dl) groups. CONCLUSIONS: In CMS patients, the decrease in PV only partially compensated for the substantial increase in Hbmass, but it did not prevent an increase in BV; the decrease in PV contributed to an excessively high [Hb].

Accuracy of Real Time Continuous Glucose Monitoring during Different Liquid Solution Challenges in Healthy Adults: A Randomized Controlled Cross-Over Trial.

Continuous glucose monitoring (CGM) represents an integral of modern diabetes management, however, there is still a lack of sensor performance data when rapidly consuming different liquids and thus changing total body water. 18 healthy adults (ten females, age: 23.1 ± 1.8 years, BMI 22.2 ± 2.1 kg·m−2) performed four trial visits consisting of oral ingestion (12 mL per kg body mass) of either a 0.9% sodium chloride, 5% glucose or Ringer's solution and a control visit, in which no liquid was administered (control). Sensor glucose levels (Dexcom G6, Dexcom Inc., San Diego, CA, USA) were obtained at rest and in 10-min intervals for a period of 120 min after solution consumption and compared against reference capillary blood glucose measurements. The overall MedARD [IQR] was 7.1% [3.3−10.8]; during control 5.9% [2.7−10.8], sodium chloride 5.0% [2.7−10.2], 5% glucose 11.0% [5.3−21.6] and Ringer's 7.5% [3.1−13.2] (p < 0.0001). The overall bias [95% LoA] was 4.3 mg·dL−1 [−19 to 28]; during control 3.9 mg·dL−1 [−11 to 18], sodium chloride 4.8 mg·dL−1 [−9 to 19], 5% glucose 3.6 mg·dL−1 [−33 to 41] and Ringer's solution 4.9 mg·dL−1 [−13 to 23]. The Dexcom G6 CGM system detects glucose with very good accuracy during liquid solution challenges in normoglycemic individuals, however, our data suggest that in people without diabetes, sensor performance is influenced by different solutions.

Myokines and Resistance Training: A Narrative Review.

In the last few years, the muscular system has gained attention due to the discovery of the muscle-secretome and its high potency for retaining or regaining health. These cytokines, described as myokines, released by the working muscle, are involved in anti-inflammatory, metabolic and immunological processes. These are able to influence human health in a positive way and are a target of research in metabolic diseases, cancer, neurological diseases, and other non-communicable diseases. Therefore, different types of exercise training were investigated in the last few years to find associations between exercise, myokines and their effects on human health. Particularly, resistance training turned out to be a powerful stimulus to enhance myokine release. As there are different types of resistance training, different myokines are stimulated, depending on the mode of training. This narrative review gives an overview about resistance training and how it can be utilized to stimulate myokine production in order to gain a certain health effect. Finally, the question of why resistance training is an important key regulator in human health will be discussed.

The Impact of a High-Carbohydrate/Low Fat vs. Low-Carbohydrate Diet on Performance and Body Composition in Physically Active Adults: A Cross-Over Controlled Trial.

Background: Recently, high-carbohydrate or low-carbohydrate (HC/LC) diets have gained substantial popularity, speculated to improve physical performance in athletes; however, the effects of short-term changes of the aforementioned nutritional interventions remain largely unclear. Methods: The present study investigated the impact of a three-week period of HC/low-fat (HC) diet followed by a three-week wash-out-phase and subsequent LC diet on the parameters of physical capacity assessed via cardiopulmonary exercise testing, body composition via bioimpedance analysis and blood profiles, which were assessed after each of the respective diet periods. Twenty-four physically active adults (14 females, age 25.8 ± 3.7 years, body mass index 22.1 ± 2.2 kg/m2), of which six participants served as a control group, were enrolled in the study. Results: After three weeks of each diet, VO2peak was comparable following both interventions (46.8 ± 6.7 (HC) vs. 47.2 ± 6.7 mL/kg/min (LC; p = 0.58)) while a significantly higher peak performance (251 ± 43 W (HC) vs. 240 ± 45 W (LC); (p = 0.0001), longer time to exhaustion (14.5 ± 2.4 min (HC) vs. 14.1 ± 2.4 min (LC); p = 0.002) and greater Watt/kg performance (4.1 ± 0.5 W/kg (HC) vs. 3.9 ± 0.5 W/kg (LC); p = 0.003) was demonstrated after the HC diet. In both trial arms, a significant reduction in body mass (65.2 ± 11.2 to 63.8 ± 11.8 kg (HC) vs. 64.8 ± 11.6 to 63.5 ± 11.3 kg (LC); both p < 0.0001) and fat mass (22.7% to 21.2%; (HC) vs. 22.3% to 20.6% (LC); both p < 0.0001) but not in lean body mass or skeletal muscle mass was shown when compared to baseline. Resting metabolic rate was not different within both groups (p > 0.05). Total cholesterol and LDL-cholesterol significantly decreased after the HC diet (97.9 ± 33.6 mg/dL at baseline to 78.2 ± 23.5 mg/dL; p = 0.02) while triglycerides significantly increased (76 ± 38 mg/dL at baseline to 104 ± 44 mg/dL; p = 0.005). Conclusion: A short-term HC and LC diet showed improvements in various performance parameters in favor of the HC diet. Some parameters of body composition significantly changed during both diets. The HC diet led to a significant reduction in total and LDL-cholesterol while triglycerides significantly increased.

Physiological Responses to Combat Sports in Metabolic Diseases: A Systematic Review.

The aim of this systematic review was to investigate how individuals with metabolic diseases respond to combat sports and if they are feasible, safe, and applicable. A systematic literature search was conducted in PubMed, from inception until 22 January 2021. Studies were included if combat sport exercise sessions were clearly defined and participants had the following types of metabolic disease: type 1 or 2 diabetes mellitus, metabolic syndrome, overweight, and obesity. Eleven studies, involving 472 participants of all age groups with type 1 diabetes mellitus, metabolic syndrome, overweight, or obesity were included in this systematic review. No studies involving combat sports and individuals with type 2 diabetes were found. Combat sports showed improved HbA1c levels over time in individuals with type 1 diabetes mellitus, which was not significantly different compared to the control group (p = 0.57). During the follow-up period, glycaemic variability decreased in those actively participating in combat sports. Fat-mass was higher in athletes performing combat sports with metabolic syndrome, compared to athletes without an increased cardiometabolic risk. In overweight/obese adolescents, combat sports showed improved parameters of physical fitness, cardio autonomic control, strength, and body composition compared to control groups. In all studies included in this systematic review, no adverse event associated with combat sports was reported. In conclusion, combat sports are safe and feasible in individuals with diabetes and/or obesity. For individuals with type 2 diabetes mellitus, no recommendations can be made, due to the lack of evidence in this cohort. Future studies investigating combat sports and metabolic diseases should aim for a structured exercise regimen and acknowledge the experience of the participants prior to starting an exercise intervention involving combat sports.