Publications by authors named "Peter Hofmann"

164 Publications

Impact of global cooling on Early Cretaceous high pCO world during the Weissert Event.

Nat Commun 2021 Sep 13;12(1):5411. Epub 2021 Sep 13.

Department of Earth Sciences Ardito Desio, University of Milan, Milan, Italy.

The Weissert Event ~133 million years ago marked a profound global cooling that punctuated the Early Cretaceous greenhouse. We present modelling, high-resolution bulk organic carbon isotopes and chronostratigraphically calibrated sea surface temperature (SSTs) based on an organic paleothermometer (the TEX proxy), which capture the Weissert Event in the semi-enclosed Weddell Sea basin, offshore Antarctica (paleolatitude ~54 °S; paleowater depth ~500 meters). We document a ~3-4 °C drop in SST coinciding with the Weissert cold end, and converge the Weddell Sea data, climate simulations and available worldwide multi-proxy based temperature data towards one unifying solution providing a best-fit between all lines of evidence. The outcome confirms a 3.0 °C ( ±1.7 °C) global mean surface cooling across the Weissert Event, which translates into a ~40% drop in atmospheric pCO over a period of ~700 thousand years. Consistent with geologic evidence, this pCO drop favoured the potential build-up of local polar ice.
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http://dx.doi.org/10.1038/s41467-021-25706-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8437947PMC
September 2021

Pattern of the Heart Rate Performance Curve in Subjects with Beta-Blocker Treatment and Healthy Controls.

J Funct Morphol Kinesiol 2021 Jul 13;6(3). Epub 2021 Jul 13.

Institute of Human Movement Science, Sport & Health, University of Graz, 8010 Graz, Austria.

(1): Heart rate performance curve (HRPC) in incremental exercise was shown to be not uniform, causing false intensity estimation applying percentages of maximal heart rate (HR). HRPC variations are mediated by β-adrenergic receptor sensitivity. The aim was to study age and sex dependent differences in HRPC patterns in adults with β-blocker treatment (BB) and healthy controls (C). (2): A total of 535 (102 female) BB individuals were matched 1:1 for age and sex (male 59 ± 11 yrs, female 61 ± 11 yrs) in C. From the maximum incremental cycle ergometer exercise a first and second heart rate (HR) threshold (Th1 and Th2) was determined. Based on the degree of the deflection (kHR), HRPCs were categorized as regular (downward deflection (kHR > 0.1)) and non-regular (upward deflection (kHR < 0.1), linear time course). (3): Logistic regression analysis revealed a higher odds ratio to present a non-regular curve in BB compared to C (females showed three times higher odds). The odds for non-regular HRPC in BB versus C decreased with older age (OR interaction = 0.97, CI = 0.94-0.99). Maximal and submaximal performance and HR variables were significantly lower in BB ( < 0.05). %HR was significantly lower in BB versus C at Th2 (male: 77.2 ± 7.3% vs. 80.8 ± 5.0%; female: 79.2 ± 5.1% vs. 84.0 ± 4.3%). %P at Th2 was similar in BB and C. (4): The HRPC pattern in incremental cycle ergometer exercise is different in individuals receiving β-blocker treatment compared to healthy individuals. The effects were also dependent on age and sex. Relative HR values at Th2 varied substantially depending on treatment. Thus, the percentage of Pmax seems to be a stable and independent indicator for exercise intensity prescription.
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http://dx.doi.org/10.3390/jfmk6030061DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8293437PMC
July 2021

The Effect of Lower Body Anaerobic Pre-Loading on Upper Body Ergometer Time Trial Performance.

Sports (Basel) 2021 May 31;9(6). Epub 2021 May 31.

Training & Training Therapy Research Group, Institute of Human Movement Science, Sport & Health, Exercise Physiology, University of Graz, 8010 Graz, Austria.

Pre-competitive conditioning has become a substantial part of successful performance. In addition to temperature changes, a metabolic conditioning can have a significant effect on the outcome, although the right dosage of such a method remains unclear. The main goal of the investigation was to measure how a lower body high-intensity anaerobic cycling pre-load exercise (HIE) of 25 s affects cardiorespiratory and metabolic responses in subsequent upper body performance. Thirteen well-trained college-level male cross-country skiers (18.1 ± 2.9 years; 70.8 ± 7.6 kg; 180.6 ± 4.7 cm; 15.5 ± 3.5% body fat) participated in the study. The athletes performed a 1000-m maximal double-poling upper body ergometer time trial performance test (TT) twice. One TT was preceded by a conventional low intensity warm-up (TT) while additional HIE cycling was performed 9 min before the other TT (TT). Maximal double-poling performance after the TT (225.1 ± 17.6 s) was similar ( > 0.05) to the TT (226.1 ± 15.7 s). Net blood lactate (La) increase (delta from end of TT minus start) from the start to the end of the TT was 10.5 ± 2.2 mmol L and 6.5 ± 3.4 mmol L in TT ( < 0.05). La net changes during recovery were similar for both protocols, remaining 13.5% higher in TT group even 6 min after the maximal test. VCO was lower ( < 0.05) during the last 400-m split in TT, however during the other splits no differences were found ( < 0.05). Respiratory exchange ratio (RER) was significantly lower in TT in the third, fourth and the fifth 200 m split. Participants individual pacing strategies showed high relation ( < 0.05) between slower start and faster performance. In conclusion, anaerobic metabolic pre-conditioning leg exercise significantly reduced net-La increase, but all-out upper body performance was similar in both conditions. The pre-conditioning method may have some potential but needs to be combined with a pacing strategy different from the usual warm-up procedure.
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http://dx.doi.org/10.3390/sports9060079DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8227393PMC
May 2021

A Mild One-Pot Reduction of Phosphine(V) Oxides Affording Phosphines(III) and Their Metal Catalysts.

Organometallics 2021 Mar 5;40(6):693-701. Epub 2021 Mar 5.

Biological and Chemical Research Centre, Faculty of Chemistry, University of Warsaw, Żwirki i Wigury Street 101, 02-089 Warsaw, Poland.

The metal-free reduction of a range of phosphine(V) oxides employing oxalyl chloride as an activating agent and hexachlorodisilane as reducing reagent has been achieved under mild reaction conditions. The method was successfully applied to the reduction of industrial waste byproduct triphenylphosphine(V) oxide, closing the phosphorus cycle to cleanly regenerate triphenylphosphine(III). Mechanistic studies and quantum chemical calculations support the attack of the dissociated chloride anion of intermediated phosphonium salt at the silicon of the disilane as the rate-limiting step for deprotection. The exquisite purity of the resultant phosphine(III) ligands after the simple removal of volatiles under reduced pressure circumvents laborious purification prior to metalation and has permitted the facile formation of important transition metal catalysts.
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http://dx.doi.org/10.1021/acs.organomet.0c00788DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8043083PMC
March 2021

Adiponectin/leptin ratio increases after a 12-week very low-carbohydrate, high-fat diet, and exercise training in healthy individuals: A non-randomized, parallel design study.

Nutr Res 2021 03 10;87:22-30. Epub 2020 Dec 10.

Sports Performance Research Institute New Zealand (SPRINZ), Auckland University of Technology, Auckland, New Zealand. Electronic address:

This study aimed to investigate the effect of a 12-week very low-carbohydrate, high-fat (VLCHF) diet and exercise on biomarkers of inflammation in healthy individuals. Since the anti-inflammatory effects of a ketogenic diet have been established, we hypothesized that the VLCHF diet, along with exercise, would have an additional favorable effect on biomarkers of inflammation. Twenty-four healthy individuals were allocated to the VLCHF diet (VLCHF: N = 12, age 25.3 ± 2.0 years, body mass 66.7 ± 9.8 kg, fat mass 21.5% ± 4.9%), or habitual diet (HD: N = 12, age 23.9 ± 3.8 years, body mass 72.7 ± 15.0 kg, fat mass 23.4 ± 8.4 %) group. Biomarkers of inflammation (adiponectin, leptin, and high-sensitive interleukin-6 [hs-IL-6]) and substrate metabolism (glycated hemoglobin, fasting glucose, triacylglycerides, and cholesterol) were analyzed from blood at baseline and after 12 weeks. The adiponectin-leptin ratio significantly increased in the VLCHF group after the intervention period (ES [95% CL]: -0.90 [-0.96, -0.77], P ≤ .001, BF = 22.15). The adiponectin-leptin ratio changes were associated with both a significant increase in adiponectin (-0.79 [-0.91, -0.54], P ≤ .001, BF = 9.43) and a significant decrease in leptin (0.58 [0.19, 0.81], P = .014, BF = 2.70). There was moderate evidence of changes in total cholesterol (-1.15 [-2.01, -0.27], P = .010, BF = 5.20), and LDL cholesterol (-1.12 [-2.01, -0.21], P = .016, BF = 4.56) in the VLCHF group. Body weight (kg) and fat mass (%) decreased in the VLCHF group by 5.4% and 14.9%, respectively. We found that in healthy young individuals, consuming a VLCHF diet while performing regular exercise over a 12-week period produced favorable changes in body weight and fat mass along with beneficial changes in serum adiponectin and leptin concentrations. These data support the use of a VLCHF diet strategy for the primary prevention of chronic diseases associated with systemic low-grade inflammation.
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http://dx.doi.org/10.1016/j.nutres.2020.12.012DOI Listing
March 2021

Beyond nitrogen: phosphorus - estimating the minimum niche dimensionality for resource competition between phytoplankton.

Ecol Lett 2021 Apr 16;24(4):761-771. Epub 2021 Feb 16.

Department of Physiological Diversity, Helmholtz-Centre for Environmental Research - UFZ, Permoserstrasse 15, Leipzig, 04318, Germany.

The niche dimensionality required for coexistence is often discussed in terms of the number of limiting resources. N and P limitation are benchmarks for studying phytoplankton interactions. However, it is generally agreed that limitation by small numbers of resources cannot explain the high phytoplankton diversity observed in nature. Here, we parameterised resource competition models using experimental data for six phytoplankton species grown in monoculture with nine potential limiting resources. We tested predicted species biomass from these models against observations in two-species experimental mixtures. Uptake rates were similar across species, following the classic Redfield ratio. Model accuracy levelled out at around three to five resources suggesting the minimum dimensionality of this system. The models included the resources Fe, Mg, Na and S. Models including only N and P always performed poorly. These results suggest that high-dimensional information about resource limitation despite stoichiometric constraints may be needed to accurately predict community assembly.
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http://dx.doi.org/10.1111/ele.13695DOI Listing
April 2021

The First Lactate Threshold Is a Limit for Heavy Occupational Work.

J Funct Morphol Kinesiol 2020 Aug 25;5(3). Epub 2020 Aug 25.

Institute of Human Movement Science, Sport and Health, University of Graz, Max-Mell-Allee 11, 8010 Graz, Austria.

Long-term heavy physical work often leads to early retirement and disability pension due to chronic overload, with a need to define upper limits. The aim of this study was to evaluate the value of the first lactate threshold (LTP) as a physiological marker for heavy occupational work. A total of 188 male and 52 female workers performed an incremental cycle ergometer test to determine maximal exercise performance and the first and second lactate (LTP; LTP) and ventilatory thresholds (VT; VT). Heart rate (HR) recordings were obtained during one eight-hour shift (HR) and oxygen uptake was measured during 20 minutes of a representative work phase. Energy expenditure (EE) was calculated from gas-exchange measures. Maximal power output (P), maximal oxygen consumption (VO) and power output at LTP and LTP were significantly different between male and female workers. HR was not significantly different between male and female workers. A significant relationship was found between P and power output at LTP. HR as a percentage of maximum HR significantly declined with increasing performance (P:r = -0.56; < 0.01; P:r = -0.49; < 0.01). Despite different cardio-respiratory fitness-levels; 95.4% of all workers performed their usual work below LTP. It is therefore suggested that LTP represents the upper limit for sustained heavy occupational work; which supports its use to determine work capability and assessing the limits of heavy occupational work.
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http://dx.doi.org/10.3390/jfmk5030066DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7739369PMC
August 2020

Capsaicin Analogue Supplementation Does Not Improve 10 km Running Time-Trial Performance in Male Amateur Athletes: A Randomized, Crossover, Double-Blind and Placebo-Controlled Study.

Nutrients 2020 Dec 24;13(1). Epub 2020 Dec 24.

Exercise and Immunometabolism Research Group, Department of Physical Education, São Paulo State University (UNESP), Presidente Prudente 19060-900, Brazil.

Background: To investigate the acute effects of a capsaicin analogue supplement on 10 km time-trial performance and physiological responses in amateur athletes.

Methods: Twenty-one participants (age = 29.3 ± 5.5 years, weight 74.2 ± 11.3 kg, height 176.0 ± 0.0 cm, fat mass 12.7 ± 3.8%, V˙O 62.7 ± 8.4 mL·k·min), completed two randomized, double-blind trials: capsaicin analogue condition (Capsiate (CAP) = 24 mg) or a placebo (PLA) condition. The participants consumed two doses of 12 mg of CAP or PLA capsule 45 min before and immediately at the start of each trial. The time required to complete 10 km, lactate concentration, maximum heart rate (HR), and rating of perceived exertion (RPE) were recorded.

Results: The 10 km time-trial performance (CAP = 45.07 ± 6.41 min vs. PLA = 45.13 ± 6.73, = 0.828) was not statistically significantly different between conditions. No statistically significant differences between conditions were detected for lactate concentration ( = 0.507), HR ( = 0.897) and RPE ( = 0.517).

Conclusion: Two doses of a 12 mg Capsaicin analogue supplement did not improve performance and physiological responses in a 10 km running time-trial in amateur athletes.
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http://dx.doi.org/10.3390/nu13010034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7823530PMC
December 2020

Regular running in an air-polluted environment: physiological and anthropometric protocol for a prospective cohort study (Healthy Aging in Industrial Environment Study - Program 4).

BMJ Open 2020 12 10;10(12):e040529. Epub 2020 Dec 10.

Institute of Human Movement Science, Sport & Health, Exercise Physiology, Training & Training Therapy Research Group, University of Graz, Graz, Austria.

Introduction: Ambient air pollution is a global environmental problem, which causes adverse health effects and premature deaths worldwide. Although regular exercise and physical activity have evident health benefits, the influence of long-term air pollution exposure during regular outdoor running has not been definitively clarified.

Methods And Analysis: This study protocol describes the physiological and anthropometric perspectives of the 'Healthy Aging in Industrial Environment' Study - Programme 4 (4HAIE). The 4HAIE research project is intended to be a single-centre, prospective, longitudinal and multidisciplinary cohort study. The presented study protocol describes the cross-sectional measurements and analyses. Overall, 1500 adult participants (age 18-65 years), runners and inactive individuals, living in a high or low air-polluted area of the Czech Republic will be recruited. We will measure and analyse biomarkers of oxidative stress and inflammation in the blood, exercise capacity (graded exercise test and spiroergometry), blood pressure, lung function (spirometry), cardiac autonomic regulation and anthropometry (body composition).

Ethics And Dissemination: The 4HAIE study protocol has already been approved by the Ethics Committee of the University of Ostrava (3/2018). A detailed participant information sheet will be provided to each individual prior to obtaining their written informed consent. The study poses little to no risk to participants. The findings of this study will be disseminated at regional and international conferences, in peer-reviewed journals and via social and broadcast media.
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http://dx.doi.org/10.1136/bmjopen-2020-040529DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7733192PMC
December 2020

Do increases in deep grey matter volumes after electroconvulsive therapy persist in patients with major depression? A longitudinal MRI-study.

J Affect Disord 2021 02 11;281:908-917. Epub 2020 Nov 11.

Department of Radiology, Division of Neuroradiology, Vascular and Interventional Radiology, 8036 Graz, Medical University of Graz, Austria; Department of Neurology, Division of General Neurology, 8036 Graz, Medical University of Graz, Austria; Research Unit for Neuronal Repair and Plasticity, 8036 Graz, Medical University of Graz, Austria. Electronic address:

Background: Previous MRI studies reported deep grey matter volume increases after electroconvulsive therapy (ECT) in patients with major depressive disorder (MDD). However, the clinical correlates of these changes are still unclear. It remains debated whether such volume changes are transient, and if they correlate with affective changes over time. We here investigated if ECT induces deep grey matter volume increases in MDD-patients; and, if so, whether volume changes persist over more than 9 months and whether they are related to the clinical outcome.

Methods: We examined 16 MDD-patients with 3Tesla MRI before (baseline) and after an ECT-series and followed 12 of them up for 10-36 months. Patients' data were compared to 16 healthy controls. Affective scales were used to investigate the relationship between therapy-outcome and MRI changes.

Results: At baseline, MDD-patients had lower values in global brain volume, white matter and peripheral grey matter compared to healthy controls, but we observed no significant differences in deep grey matter volumes. After ECT, the differences in peripheral grey matter disappeared, and patients demonstrated significant volume increases in the right hippocampus and both thalami, followed by subsequent decreases after 10-36 months, especially in ECT-responders. Controls did not show significant changes over time.

Limitations: Beside the relatively small, yet carefully characterized cohort, we address the variability in time between the third scanning session and the baseline.

Conclusions: ECT-induced deep grey matter volume increases are transient. Our results suggest that the thalamus might be a key region for the understanding of the mechanisms of ECT action.
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http://dx.doi.org/10.1016/j.jad.2020.11.035DOI Listing
February 2021

Differences in Physiological Responses to Cardiopulmonary Exercise Testing in Adults With and Without Type 1 Diabetes: A Pooled Analysis.

Diabetes Care 2021 01 12;44(1):240-247. Epub 2020 Nov 12.

Cardiovascular Diabetology Research Group, Division of Endocrinology and Diabetology, Department of Internal Medicine, Medical University of Graz, Graz, Austria

Objective: To investigate physiological responses to cardiopulmonary exercise (CPX) testing in adults with type 1 diabetes compared with age-, sex-, and BMI-matched control participants without type 1 diabetes.

Research Design And Methods: We compared results from CPX tests on a cycle ergometer in individuals with type 1 diabetes and control participants without type 1 diabetes. Parameters were peak and threshold variables of VO, heart rate, and power output. Differences between groups were investigated through restricted maximum likelihood modeling and post hoc tests. Differences between groups were explained by stepwise linear regressions ( < 0.05).

Results: Among 303 individuals with type 1 diabetes (age 33 [interquartile range 22; 43] years, 93 females, BMI 23.6 [22; 26] kg/m, HbA 6.9% [6.2; 7.7%] [52 (44; 61) mmol/mol]), VO (32.55 [26.49; 38.72] vs. 42.67 ± 10.44 mL/kg/min), peak heart rate (179 [170; 187] vs. 184 [175; 191] beats/min), and peak power (216 [171; 253] vs. 245 [200; 300] W) were lower compared with 308 control participants without type 1 diabetes (all < 0.001). Individuals with type 1 diabetes displayed an impaired degree and direction of the heart rate-to-performance curve compared with control participants without type 1 diabetes (0.07 [-0.75; 1.09] vs. 0.66 [-0.28; 1.45]; < 0.001). None of the exercise physiological responses were associated with HbA in individuals with type 1 diabetes.

Conclusions: Individuals with type 1 diabetes show altered responses to CPX testing, which cannot be explained by HbA. Intriguingly, the participants in our cohort were people with recent-onset type 1 diabetes; heart rate dynamics were altered during CPX testing.
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http://dx.doi.org/10.2337/dc20-1496DOI Listing
January 2021

Absolute Accelerometer-Based Intensity Prescription Compared to Physiological Variables in Pregnant and Nonpregnant Women.

Int J Environ Res Public Health 2020 08 5;17(16). Epub 2020 Aug 5.

Institute of Human Movement Science, Sport and Health, University of Graz, 8010 Graz, Austria.

Estimation of the intensity of physical activity (PA) based on absolute accelerometer cut points (Cp) likely over- or underestimates intensity for a specific individual. The purpose of this study was to investigate the relationship between absolute moderate intensity Cp and the first ventilatory threshold (VT). A group of 24 pregnant and 15 nonpregnant women who performed a submaximal incremental walking test with measures of ventilatory parameters and accelerations from three different accelerometers on the wrist (ActiGraph wGT3X-BT, GENEActiv, Axivity AX3) and one on the hip (Actigraph wGT3X-BT) were analyzed. Cp were determined corresponding to 3 metabolic equivalents of task (MET), using the conventional MET definition (Cp) (3.5 mL/kg×min) and individual resting metabolic rate (Cp). The ventilatory equivalent (VE/VO) was used to determine VT. Accelerations at VT were significantly higher ( < 0.01) compared to Cp and Cp in both groups. Cp and Cp were significantly different in nonpregnant ( < 0.01) but not in pregnant women. Walking speed at VT (5.7 ± 0.5/6.2 ± 0.8 km/h) was significantly lower ( < 0.01) in pregnant compared to nonpregnant women and correspondent to 3.8 ± 0.7/4.9 ± 1.4 conventional METs. Intensity at absolute Cp was lower compared to the intensity at VT independent of the device or placement in pregnant and nonpregnant women. Therefore, we recommend individually tailored cut points such as the VT to better assess the effect of the intensity of PA.
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http://dx.doi.org/10.3390/ijerph17165651DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7460197PMC
August 2020

General and Disease-Specific Health Indicator Changes Associated with Inpatient Rehabilitation.

J Am Med Dir Assoc 2020 12 28;21(12):2017.e10-2017.e27. Epub 2020 Jul 28.

Division of Physiology, Otto Loewi Research Center, Medical University of Graz, Graz, Austria; Human Research Institute, Weiz, Austria.

Objectives: Rehabilitation plays a vital role in the mitigation and improvement of functional limitations associated with aging and chronic conditions. Moderating factors such as sex, age, the medical diagnosis, and rehabilitation timing for admission status, as well as the expected change related to inpatient rehabilitation, are examined to provide a valid basis for the routine assessment of the quality of medical outcomes.

Design: An observational study was carried out, placing a focus on general and disease-specific health measurements, to assess representative results of multidisciplinary inpatient rehabilitation. Aspects that were possibly confounding and introduced bias were controlled based on data from a quasi-experimental (waiting) control group.

Measures: Existing data or general health indicators were extracted from medical records. The indicators included blood pressure, resting heart rate, self-assessed health, and pain, as well as more disease-specific indicators of physical function and performance (eg, activities of daily living, walking tests, blood lipids). These are used to identify moderating factors related to health outcomes.

Setting And Participants: A standardized collection of routine data from 16,966 patients [61.5 ± 12.5 years; 7871 (46%) women, 9095 (54%) men] with different medical diagnoses before and after rehabilitation were summarized using a descriptive evaluation in terms of a content and factor analysis.

Results: Without rehabilitation, general health indicators did not improve independently and remained stable at best [odds ratio (OR) = 0.74], whereas disease-specific indicators improved noticeably after surgery (OR = 3.20). Inpatient rehabilitation was shown to reduce the risk factors associated with certain lifestyles, optimize organ function, and improve well-being in most patients (>70%; cutoff: z-difference >0.20), with a standardized mean difference (SMD) seen in overall medical quality outcome of -0.48 ± 0.37 [pre- vs post-rehabilitation: η = 0.622; d = -1.22; 95% confidence interval (95% CI) -1.24 to -1.19]. The baseline medical values obtained at the beginning of rehabilitation were influenced by indication, age, and sex (all P < .001); however, these factors have less significant effects on improvements in general health indicators (η < 0.01). According to the disease-specific results, the greatest improvements were found in older patients (SMD for patients >60 vs ≤60 years: 95% CI 0.08-0.11) and during the early rehabilitation stage (η = 0.063).

Conclusions And Implications: Compared with those who received no inpatient rehabilitation, patients who received rehabilitation showed greater improvements in 2 independent areas, general and disease-specific health measures, regardless of their diagnosis, age, and sex. Due to the study design and the use of a nonrandomized waiting group, causal conclusions must be drawn with caution. However, the comparability and stability of the presented results strongly support the validity of the observed improvements associated with inpatient rehabilitation.
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http://dx.doi.org/10.1016/j.jamda.2020.05.034DOI Listing
December 2020

Efficacy of Carbohydrate Supplementation Compared With Bolus Insulin Dose Reduction Around Exercise in Adults With Type 1 Diabetes: A Retrospective, Controlled Analysis.

Can J Diabetes 2020 Dec 22;44(8):697-700. Epub 2020 Mar 22.

Cardiovascular Diabetology Research Group, Division of Endocrinology and Diabetology, Medical University of Graz, Graz, Austria. Electronic address:

Objectives: Individuals with type 1 diabetes try to manage the risk of exercise-induced hypoglycemia by either pre-exercise/pre-meal bolus insulin dose reductions and/or consuming additional carbohydrates during exercise. Both strategies have proven to be effective in offsetting hypoglycemia, but it remains unclear which one is more beneficial. The aim of this study was to assess the efficacy of carbohydrate supplementation vs bolus insulin dose reduction in prevention of hypoglycemia during moderate-intensity exercise in those with type 1 diabetes.

Methods: This investigation was a retrospective, controlled analysis of 2 independent clinical trials. All participants performed continuous, moderate-intensity cycle ergometer exercise for ∼45 minutes. Two therapy management groups and a control group were compared. Group A was supplemented with 15 to 30 g carbohydrates at a glycemic threshold of 7.0 mmol/L during exercise, group B reduced their individual bolus insulin dose by 50% with their last meal before exercise and group C served as a control.

Results: No hypoglycemic events occurred in group A, whereas 4 events were recorded in groups B (p=0.02) and C (p=0.02).

Conclusions: Carbohydrate supplementation was superior to bolus insulin reduction for prevention of hypoglycemia during exercise in people with type 1 diabetes.
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http://dx.doi.org/10.1016/j.jcjd.2020.03.003DOI Listing
December 2020

Intensity Thresholds and Maximal Lactate Steady State in Small Muscle Group Exercise.

Sports (Basel) 2020 May 28;8(6). Epub 2020 May 28.

Exercise Physiology, Training & Training Therapy Research Group, Institute of Sports Science, University of Graz, 8010 Graz, Austria.

The aim of our study is to determine the first (LTP) and the second (LTP) lactate turn points during an incremental bicep curl test and to verify these turn points by ventilatory turn points (VT and VT) and constant-load exercise tests. Twelve subjects performed a one-arm incremental bicep curl exercise (IET) after a one repetition maximum (1RM) test to calculate the step rate for the incremental exercise (1RM/45). Workload was increased every min at a rate of 30 reps/min until maximum. To verify LTPs, VT and VT were determined from spirometric data, and 30 min constant-load tests (CL) were performed at 5% P below and above turn points. Peak load in IET was 5.3 ± 0.9 kg (La: 2.20 ± 0.40 mmol·L; HR: 135 ± 15 b·min; VO: 1.15 ± 0.30 L·min). LTP was detected at 1.9 ± 0.6 kg (La: 0.86 ± 0.36 mmol·L; HR 90 ± 13 b·min; VO: 0.50 ± 0.05 L·min) and LTP at 3.8 ± 0.7 kg (La: 1.38 ± 0.37 mmol·L; 106 ± 10 b·min; VO: 0.62 ± 0.11 L·min). Constant-load tests showed a lactate steady-state in all tests except above LTP, with early termination after 16.5 ± 9.1 min. LTP and LTP could be determined in IET, which were not significantly different from VT/VT. Constant-load exercise validated the three-phase concept, and a steady-state was found at resting values below VT and in all other tests except above LTP. It is suggested that the three-phase model is also applicable to small muscle group exercise.
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http://dx.doi.org/10.3390/sports8060077DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7353667PMC
May 2020

Heart Rate Performance Curve Is Dependent on Age, Sex, and Performance.

Front Public Health 2020 2;8:98. Epub 2020 Apr 2.

Exercise Physiology, Training & Training Therapy Research Group, Institute of Sports Science, University of Graz, Graz, Austria.

The Heart Rate Performance Curve (HRPC) is neither linear nor uniform and related to ß1-adrenoceptor sensitivity. As aging and exercise influence ß1-adrenoceptors we suggested age, sex and performance effects on the HRPC. Aim of the study was to examine the effects of aging on the deflection of the HRPC in maximal incremental cycle ergometer exercise (CE) in a large cohort of healthy subjects. Heart rate (HR) data of 2,980 men (51 ± 15 years) and 1,944 women (52 ± 14 years) were classified into age groups (≤20 up to >80 years). We analyzed age and performance (P 25%-quartile and P 75%-quartile of age predicted power) effects on HR and on the degree () and the type (regular downward deflection > 0.1, linear -0.1 ≤ ≤ 0.1 and atypical upward deflection < -0.1) of the HRPC. -values decreased significantly with age in men and women and were significantly higher in women. Atypical HRPC's increased by a linear trend from ≤20 to 70 years () respectively 80 years () from 10 to 43% () and 9 to 30% (). HR of all age groups was lower in P and overall number of atypical HRPC's was 21% () and 16% () higher compared to P. Aging increased the number of atypical HRPC's with upward deflection in CE tests, which influences exercise intensity prescription especially when using fixed percentages of HR. Changes in HRPC's were affected by sex and performance, where women generally and subjects with higher performance presented less atypical HRPC's even at older age.
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http://dx.doi.org/10.3389/fpubh.2020.00098DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7144539PMC
May 2021

Efficacy of extended, comprehensive outpatient cardiac rehabilitation on cardiovascular risk factors: A nationwide registry.

Eur J Prev Cardiol 2020 07 14;27(10):1026-1033. Epub 2020 Jan 14.

Institute of Sports Medicine, Prevention and Rehabilitation Research Institute of Molecular Sports Medicine and Rehabilitation, Paracelsus Medical University Salzburg, Salzburg, Austria.

Aim: Cardiac rehabilitation (CR) is a key component of the treatment of cardiac diseases. The Austrian outpatient CR model is unique, as it provides patients with an extended professionally supervised, multidisciplinary program of 4-6 weeks of phase II (OUT-II) and 6-12 months of phase III (OUT-III) CR. The aim of this analysis was to assess the efficacy of the Austrian outpatient CR model using a nationwide registry.

Methods: Data of all consecutive patients ( = 7560) who completed OUT-II and/or OUT-III between 1 January 2005 and 31 December 2015 were entered prospectively into a registry. OUT-III patients were analyzed separately according to whether the preceding phase II was performed as outpatient (OUT-II/OUT-III,  = 2403) or in-patient (IN-II/OUT-III,  = 2789). All patients underwent assessment of anthropometry, resting blood pressure, lipid profile, fasting blood glucose, exercise capacity, quality of life, anxiety and depression.

Results: During OUT-II, patients significantly improved their metabolic risk factor profile and increased exercise capacity by 14.3%. OUT-II/OUT-III patients achieved an additional increase in exercise capacity by 10%, further improvement in high-density lipoprotein (HDL) and stabilization of the remaining risk factors. IN-II/OUT-III patients increased their maximal exercise capacity by 18.4% and there was improvement in blood pressure, HDL, low-density lipoprotein and glucose levels.

Conclusion: Extended, professionally supervised, multidisciplinary outpatient CR in a large nationwide registry of consecutive patients consistently improved maximal exercise capacity and relevant modifiable cardiovascular risk factors beyond effects seen after IN- or OUT-II alone.
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http://dx.doi.org/10.1177/2047487319898958DOI Listing
July 2020

Type 1 Diabetes and Physical Exercise: Moving (forward) as an Adjuvant Therapy.

Curr Pharm Des 2020 ;26(9):946-957

Exercise Physiology, Training & Training Therapy Research Group, Institute of Sports Science, University of Graz, Graz, Austria.

Type 1 diabetes is characterized by an autoimmune β-cell destruction resulting in endogenous insulin deficiency, potentially leading to micro- and macrovascular complications. Besides an exogenous insulin therapy and continuous glucose monitoring, physical exercise is recommended in adults with type 1 diabetes to improve overall health. The close relationship between physical exercise, inflammation, muscle contraction, and macronutrient intake has never been discussed in detail about type 1 diabetes. The aim of this narrative review was to detail the role of physical exercise in improving clinical outcomes, physiological responses to exercise and different nutrition and therapy strategies around exercise. Physical exercise has several positive effects on glucose uptake and systemic inflammation in adults with type 1 diabetes. A new approach via personalized therapy adaptations must be applied to target beneficial effects on complications as well as on body weight management. In combination with pre-defined macronutrient intake around exercise, adults with type 1 diabetes can expect similar physiological responses to physical exercise, as seen in their healthy counterparts. This review highlights interesting findings from recent studies related to exercise and type 1 diabetes. However, there is limited research available accompanied by a proper number of participants in the cohort of type 1 diabetes. Especially for this group of patients, an increased understanding of the impact of physical exercise can improve its effectiveness as an adjuvant therapy to move (forward).
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http://dx.doi.org/10.2174/1381612826666200108113002DOI Listing
November 2020

Temperature and stoichiometric dependence of phytoplankton traits.

Ecology 2019 12 18;100(12):e02875. Epub 2019 Oct 18.

Department of Physiological Diversity, Helmholtz-Centre for Environmental Research - UFZ, Permoserstrasse 15, Leipzig, 04318, Germany.

Understanding the links between intraspecific trait variability and environmental gradients is an important step toward unravelling the mechanisms that link species performance to environmental variation. Here, we performed a comparative, experimental study to investigate variability of cellular traits in three prokaryotic and three eukaryotic freshwater phytoplankton species along gradients of temperature and nitrogen:phosphorus ratio (N:P) in laboratory microcosms. Temperature and N:P strongly affect phytoplankton growth and are changing due to climate change and eutrophication. Metabolic theory and allometric scaling predict that smaller organisms should be favored at higher temperatures through improved metabolic uptake partly due to greater surface area to volume ratios. In addition, chlorophyll a (chl a) concentration should increase due to higher chlorophyll synthesis in response to light limitation at higher cell densities. We found that cell volume both increased and decreased with temperature, whereas intermediate N:P yielded higher growth rates and more extreme conditions yielded bigger cell volumes. Species growth responses to these gradients were distinct and not related to phylogenetic differences. Meaningfully coupled traits like the chl a fluorescence and cell volume shifted consistently and can improve our understanding of individual cell responses to abiotic drivers. This study showed that intraspecific trait variability of freshwater phytoplankton harbors potential for short term acclimation to environmental gradients. Finally, the high trait variability in some species has strong implications for their ecology and the accuracy of predictions where responses may differ when based on mean or fixed trait values.
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http://dx.doi.org/10.1002/ecy.2875DOI Listing
December 2019

Effects of a 12-Week Very-Low Carbohydrate High-Fat Diet on Maximal Aerobic Capacity, High-Intensity Intermittent Exercise, and Cardiac Autonomic Regulation: Non-randomized Parallel-Group Study.

Front Physiol 2019 17;10:912. Epub 2019 Jul 17.

Department of Human Movement Studies, Human Motion Diagnostic Centre, University of Ostrava, Ostrava, Czechia.

Purpose: The aim of this non-randomized parallel group study was to examine the 12 week effects of a very low-carbohydrate high-fat diet (VLCHF) on maximal cardiorespiratory capacity, high-intensity interval training (HIIT) performance, and cardiac autonomic regulation.

Methods: Twenty-four recreationally trained participants allocated to either a VLCHF ( = 12) or a habitual diet (HD; = 12) group completed 12 weeks of a diet and exercise (VLCHF) or an exercise only intervention (HD). Maximal graded exercise tests (GXT) were performed at baseline, after 4, 8, and 12 weeks. A supervised HIIT session and the 30-15 Intermittent Fitness Test (30-15) were conducted once a week.

Results: Total time to exhaustion (TTE) in both GXT and 30-15 increased in both VLCHF ( = 0.005, BF = 11.30 and = 0.001, BF ≥ 100, respectively) and HD ( = 0.018, BF = 3.87 and = 0.001, BF ≥ 100, respectively) groups after 12 weeks. Absolute maximal oxygen uptake ( O) was not changed in both groups but relative O increased in VLCHF in concert with reductions in body mass (66.7 ± 10.2-63.1 ± 8.5 kg). Cardiac autonomic regulation did not reveal any between-group differences after 12 weeks. VLCHF diet induced an increase in β-hydroxybutyrate, which tended to normalize during the intervention period.

Conclusion: The 12 week VLCHF diet did not impair high-intensity continuous or intermittent exercise lasting up to 25 min, nor did it impair maximal cardiorespiratory performance or autonomic nervous system (ANS) activity.
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http://dx.doi.org/10.3389/fphys.2019.00912DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6652046PMC
July 2019

The future is now: SGLT2 inhibitors and type 1 diabetes - What about exercise?

Diabetes Res Clin Pract 2019 09 1;155:107806. Epub 2019 Aug 1.

Division of Endocrinology and Diabetology, Department of Internal Medicine, Medical University of Graz, Graz, Austria.

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http://dx.doi.org/10.1016/j.diabres.2019.107806DOI Listing
September 2019

Pre-Exercise Blood Glucose Levels Determine the Amount of Orally Administered Carbohydrates during Physical Exercise in Individuals with Type 1 Diabetes-A Randomized Cross-Over Trial.

Nutrients 2019 Jun 6;11(6). Epub 2019 Jun 6.

Division of Endocrinology and Diabetology, Department of Internal Medicine, Medical University of Graz, 8036 Graz, Austria.

The aim of the study was to assess the amount of orally administered carbohydrates needed to maintain euglycemia during moderate-intensity exercise in individuals with type 1 diabetes. Nine participants with type 1 diabetes (four women, age 32.1 ± 9.0 years, BMI 25.5 ± 3.9 kg/m, HbA 55 ± 7 mmol/mol (7.2 ± 0.6%)) on insulin Degludec were randomized to cycle for 55 min at moderate intensity (63 ± 7% VO) for five consecutive days on either 75% or 100% of their regular basal insulin dose. The impact of pre-exercise blood glucose concentration on the carbohydrate requirement was analyzed by one-way ANOVA stratified for pre-exercise blood glucose quartiles. The effect of the basal insulin dose on the amount of orally administered carbohydrates was evaluated by Wilcoxon matched-pairs signed-rank test. The amount of orally administered carbohydrates during the continuous exercise sessions was similar for both trial arms (75% or 100% basal insulin) with median [IQR] of 36 g (9-62 g) and 36 g (9-66 g) ( = 0.78). The amount of orally administered carbohydrates was determined by pre-exercise blood glucose concentration for both trial arms ( = 0.03). Our study elucidated the importance of pre-exercise glucose concentration related orally administered carbohydrates to maintain euglycemia during exercise in individuals with type 1 diabetes.
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http://dx.doi.org/10.3390/nu11061287DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6627914PMC
June 2019

[Mental disorders and diabetes mellitus (Update 2019)].

Wien Klin Wochenschr 2019 May;131(Suppl 1):186-195

Klinische Abteilung für Endokrinologie und Diabetologie, Universitätsklinik für Innere Medizin, Medizinische Universität Graz, Graz, Österreich.

Psychiatric disorders and psychological problems are common in patients with diabetes mellitus. There is a twofold increase in depression which is associated with suboptimal glycemic control and increased morbidity and mortality. Other psychiatric disorders with a higher incidence of diabetes mellitus are cognitive impairment, dementia, disturbed eating behavior, anxiety disorders, schizophrenia, bipolar disorders and borderline personality disorder. The coincidence of mental disorders and diabetes mellitus has unfavorable influences on metabolic control and micro- and macroangiopathic complications. Improvement of therapeutic outcome is a challenge in the modern health care system. The intentions behind this position paper are to rise awareness of this special set of problems, to intensify cooperation between involved health care providers and to reduce incidence of diabetes mellitus as well as morbidity and mortality from diabetes in this patient group.
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http://dx.doi.org/10.1007/s00508-019-1458-9DOI Listing
May 2019

Psychophysiological concomitants of burnout: Evidence for different subtypes.

J Psychosom Res 2019 03 18;118:41-48. Epub 2019 Jan 18.

Institute of Psychology, Health Psychology Unit, University of Graz, Graz, Austria.

Background: There is evidence that chronic stress and emotional exhaustion are related to physiological dysregulations, which could negatively impact physical and mental health. This study aimed to identify the specific physiological clusters which are most reliable and prominently associated with burnout. Emphasis was placed on variables of the autonomic nervous system and hypothalamic-pituitary-adrenal axis. Burnout was assessed using the Emotional Exhaustion subscale of the German version of the Maslach Burnout Inventory (MBI-GS).

Methods: A sample of 105 individuals aged between 28 and 60 years (M = 42.7, SD = 7.75) and working under highly demanding conditions participated in this study. 46 participants reported a low risk of burnout, and 58 participants a high risk. They underwent 24 h of ECG monitoring, had cortisol awakening response collected, and had blood pressure measured two times within a week.

Results: Compromised HRV, higher cortisol values, and higher blood pressure were found in individuals with high burnout symptoms. Furthermore, a discriminant function analysis on cardiac and neuroendocrine variables suggested two subgroups within the high burnout individuals, with only one group showing evidence for autonomic dysfunction as indicated by lower vagal efference.

Conclusions: Results suggest that burnout might not necessarily imply physiological disturbances, thus calling for a more differentiated and individualized view of burnout.
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http://dx.doi.org/10.1016/j.jpsychores.2019.01.009DOI Listing
March 2019

CAMISIM: simulating metagenomes and microbial communities.

Microbiome 2019 02 8;7(1):17. Epub 2019 Feb 8.

Computational Biology of Infection Research, Helmholtz Centre for Infection Research, Braunschweig, 38124, Germany.

Background: Shotgun metagenome data sets of microbial communities are highly diverse, not only due to the natural variation of the underlying biological systems, but also due to differences in laboratory protocols, replicate numbers, and sequencing technologies. Accordingly, to effectively assess the performance of metagenomic analysis software, a wide range of benchmark data sets are required.

Results: We describe the CAMISIM microbial community and metagenome simulator. The software can model different microbial abundance profiles, multi-sample time series, and differential abundance studies, includes real and simulated strain-level diversity, and generates second- and third-generation sequencing data from taxonomic profiles or de novo. Gold standards are created for sequence assembly, genome binning, taxonomic binning, and taxonomic profiling. CAMSIM generated the benchmark data sets of the first CAMI challenge. For two simulated multi-sample data sets of the human and mouse gut microbiomes, we observed high functional congruence to the real data. As further applications, we investigated the effect of varying evolutionary genome divergence, sequencing depth, and read error profiles on two popular metagenome assemblers, MEGAHIT, and metaSPAdes, on several thousand small data sets generated with CAMISIM.

Conclusions: CAMISIM can simulate a wide variety of microbial communities and metagenome data sets together with standards of truth for method evaluation. All data sets and the software are freely available at https://github.com/CAMI-challenge/CAMISIM.
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http://dx.doi.org/10.1186/s40168-019-0633-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6368784PMC
February 2019

Impact to short-term high intensity intermittent training on different storages of body fat, leptin and soluble leptin receptor levels in physically active non-obese men: A pilot investigation.

Clin Nutr ESPEN 2018 12 7;28:186-192. Epub 2018 Sep 7.

Exercise and Immunometabolism Research Group, Department of Physical Education, Universidade Estadual Paulista (Unesp), School of Technology and Science, Presidente Prudente, São Paulo, Brazil. Electronic address:

Background & Aims: Studies have postulated High Intensity Intermittent Training (HIIT) as a superior strategy to reduce body fat. The purpose of this study was to compare the effects HIIT and steady-state training (SST) on body composition, leptin, soluble leptin receptor (sOB-R) levels, and hunger perception in physically active non-obese men.

Methods: Twenty men performed five weeks of HIIT (5 km - 1 min running at 100% speed correspondent to VȩO - v VȩO - interspersed with 1-min passive recovery; n = 10) or SST (5 km at 70% of vVȩO continuously; n = 10) three times a week. Body composition, and hunger perception were assessed at pre- and post-training and were compared by a two-way analysis (group and training period) with repeated measures in the second factor. A fasting time-course (baseline, 24 h, and 48 h after an experimental session of exercise) of leptin and sOB-R levels were measured at pre- and post-five weeks of training and assessed by a three-way analysis (group, period and time of measurement) with repeated measures in the second and third factors.

Results: There was no effect on body composition and hunger perception. Leptin was reduced in both groups, while sOB-R was increased post-five weeks of training in HIIT but not in the SST.

Conclusions: Although both training groups exerted alterations in leptin levels, only HIIT was able increased sOB-R levels, this suggest a superior impact on central responses in physically active non-obese men.
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http://dx.doi.org/10.1016/j.clnesp.2018.08.005DOI Listing
December 2018

Different Heart Rate Patterns During Cardio-Pulmonary Exercise (CPX) Testing in Individuals With Type 1 Diabetes.

Front Endocrinol (Lausanne) 2018 2;9:585. Epub 2018 Oct 2.

Exercise Physiology, Training Therapy & Training Research Group, Institute of Sports Sciences, University of Graz, Graz, Austria.

To investigate the heart rate during cardio-pulmonary exercise (CPX) testing in individuals with type 1 diabetes (T1D) compared to healthy (CON) individuals. Fourteen people (seven individuals with T1D and seven CON individuals) performed a CPX test until volitional exhaustion to determine the first and second lactate turn points (LTP and LTP), ventilatory thresholds (VT and VT), and the heart rate turn point. For these thresholds cardio-respiratory variables and percentages of maximum heart rate, heart rate reserve, maximum oxygen uptake and oxygen uptake reserve, and maximum power output were compared between groups. Additionally, the degree and direction of the deflection of the heart rate to performance curve (k) were compared between groups. Individuals with T1D had similar heart rate at LTP (mean difference) -11, [(95% confidence interval) -27 to 4 b.min], at VT (-12, -8 to 33 b.min) and at LTP (-7, -13 to 26 b.min), at VT (-7, -13 to 28 b.min), and at the heart rate turn point (-5, -14 to 24 b.min) ( = 0.22). Heart rate expressed as percentage of maximum heart rate at LTP, VT, LTP, VT and the heart rate turn point as well as expressed as percentages of heart rate reserve at LTP, VT and the heart rate turn point was lower in individuals with T1D ( < 0.05). k was lower in T1D compared to CON individuals (0.11 ± 0.25 vs. 0.51 ± 0.32, = 0.02). Our findings demonstrate that there are clear differences in the heart rate response during CPX testing in individuals with T1D compared to CON individuals. We suggest using submaximal markers to prescribe exercise intensity in people with T1D, as the heart rate at thresholds is influenced by k. NCT02075567 (https://clinicaltrials.gov/ct2/show/NCT02075567).
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http://dx.doi.org/10.3389/fendo.2018.00585DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6176070PMC
October 2018

Reduction in insulin degludec dosing for multiple exercise sessions improves time spent in euglycaemia in people with type 1 diabetes: A randomized crossover trial.

Diabetes Obes Metab 2019 02 14;21(2):349-356. Epub 2018 Oct 14.

Division of Endocrinology and Diabetology, Department of Internal Medicine, Medical University of Graz, Graz, Austria.

Aims: To compare the time spent in specified glycaemic ranges in people with type 1 diabetes (T1D) during 5 consecutive days of moderate-intensity exercise while on either 100% or 75% of their usual insulin degludec (IDeg) dose.

Materials And Methods: Nine participants with T1D (four women, mean age 32.1 ± 9.0 years, body mass index 25.5 ± 3.8 kg/m , glycated haemoglobin 55 ± 7 mmol/mol (7.2% ± 0.6%) on IDeg were enrolled in the trial. Three days before the first exercise period, participants were randomized to either 100% or 75% of their usual IDeg dose. Participants exercised on a cycle ergometer for 55 minutes at a moderate intensity for 5 consecutive days. After a 4-week wash-out period, participants performed the last exercise period for 5 consecutive days with the alternate IDeg dose. Time spent in specified glycaemic ranges, area under the curve and numbers of hypoglycaemic events were compared for the 5 days on each treatment allocation using a paired Students' t test, Wilcoxon matched-pairs signed-rank test and two-way ANOVA.

Results: Time spent in euglycaemia over 5 days was greater for the 75% IDeg dose versus the 100% IDeg dose (4008 ± 938 minutes vs. 3566 ± 856 minutes; P = 0.04). Numbers of hypoglycaemic events (P = 0.91) and time spent in hypoglycaemia (P = 0.07) or hyperglycaemia (P = 0.38) was similar for both dosing schemes.

Conclusions: A 25% reduction in usual IDeg dose around regular exercise led to more time spent in euglycaemia, with small effects on time spent in hypo- and hyperglycaemia.
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http://dx.doi.org/10.1111/dom.13534DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6587463PMC
February 2019

Effects of 6 Weeks of Different High-Intensity Interval and Moderate Continuous Training on Aerobic and Anaerobic Performance.

J Strength Cond Res 2019 Jan;33(1):44-56

Exercise Physiology, Training & Training Therapy Research Group, Institute of Sports Science, University of Graz, Graz, Austria.

Cavar, M, Marsic, T, Corluka, M, Culjak, Z, Cerkez Zovko, I, Müller, A, Tschakert, G, and Hofmann, P. Effects of 6 weeks of different high-intensity interval and moderate continuous training on aerobic and anaerobic performance. J Strength Cond Res 33(1): 44-56, 2019-To provide practical data, we compared the training effects of 3 different programs, using a shuttle run stimulus, on aerobic and anaerobic performance, measured using the 20-m maximal shuttle run (Beep) test and 300-yd shuttle run, respectively. Forty-five physically trained men, with a mean age of 21.1 ± 1.8 years, participated. The 6-week, 12-session training programs included 2 high-intensity interval training (HIIT) protocols, with either a short (SH) or long (LH) shuttle run interval, and a continuous shuttle run (CON), which was used as a control. The training intensity was based on the maximal shuttle run speed (MASS), measured on the Beep test, to elicit the relevant values of the time to exhaustion (TTE). Short (SH) training was performed at 115-120%(MASS), with a 10-second work to 10-second rest scheme, and the number of repetitions to be completed set to 70% of each participant's maximum (∼15 repetitions). LH training was performed at an intensity of 90-95%(MASS), with the duration set to 70%(TTE) (∼4 minutes). For both SH and LH, 3 sets were completed at each session, with a 2-3 minutes of rest between sets. CON training consisted of continuous shuttle running for 35 minutes at an intensity of 70%(MASS). Both SH and LH yielded a large training effect (p < 0.01), with SH preferentially improving anaerobic performance and LH preferentially improving aerobic performance. No effect of CON training was identified. Our findings indicate that these different training protocols cannot be used interchangeably and that the Beep test is useful in prescribing the intensity and duration of HIIT.
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http://dx.doi.org/10.1519/JSC.0000000000002798DOI Listing
January 2019

Performance Enhancing Effect of Metabolic Pre-conditioning on Upper-Body Strength-Endurance Exercise.

Front Physiol 2018 20;9:963. Epub 2018 Jul 20.

Institute of Sports Science, Exercise Physiology, Training and Training Therapy Research Group, University of Graz, Graz, Austria.

High systemic blood lactate (La) was shown to inhibit glycolysis and to increase oxidative metabolism in subsequent anaerobic exercise. Aim of this study was to examine the effect of a metabolic pre-conditioning (MPC) on net La increase and performance in subsequent pull-up exercise (PU). Nine trained students (age: 25.1 ± 1.9 years; BMI: 21.7 ± 1.4) performed PU on a horizontal bar with legs placed on a box (angular hanging) either without or with MPC in a randomized order. MPC was a 26.6 ± 2 s all out shuttle run. Each trial started with a 15-min warm-up phase. Time between MPC and PU was 8 min. Heart rate (HR) and gas exchange measures (VO, VCO, and VE) were monitored, La and glucose were measured at specific time points. Gas exchange measures were compared by area under the curve (AUC). In PU without MPC, La increased from 1.24 ± 0.4 to 6.4 ± 1.4 mmol⋅l, whereas with MPC, PU started at 9.28 ± 1.98 mmol⋅l La which increased to 10.89 ± 2.13 mmol⋅l. With MPC, net La accumulation was significantly reduced by 75.5% but performance was significantly increased by 1 rep (4%). Likewise, net oxygen uptake VO (50% AUC), pulmonary ventilation (VE) (34% AUC), and carbon dioxide VCO production (26% AUC) were significantly increased during PU but respiratory exchange ratio (RER) was significantly blunted during work and recovery. MPC inhibited glycolysis and increased oxidative metabolism and performance in subsequent anaerobic upper-body strength-endurance exercise.
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http://dx.doi.org/10.3389/fphys.2018.00963DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6062767PMC
July 2018
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