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  • 51.
    Koptioug, Andrei
    et al.
    Department of Biomedical Physics and Bioengineering, University of Aberdeen, Aberdeen, UK.
    Foster, Margaret
    Grigor’ev, Igor
    Lurie, David
    Khramtsov, Valerij
    McCallum, S.
    Panagiotelis, I.
    Nicholson, I.
    In Vivo Detection of a pH-Sensitive Nitroxide in the Rat Stomach by Low-Field ESR-Based Techniques2003In: Magnetic Resonance in Medicine, ISSN 0740-3194, E-ISSN 1522-2594, Vol. 49, no 3, p. 558-567Article in journal (Refereed)
    Abstract [en]

    A study was made of the in vivo detectability of a pH-sensitive, imidazolidine spin probe, and the efficacy of low-frequency electron spin resonance (ESR)-based techniques for pH measurement in vitro and in vivo in rats. The techniques used were longitudinally-detected ESR (LODESR) and field-cycled dynamic nuclear polarization (FC-DNP) for in vitro and in vivo measurements, and radiofrequency (RF)- and X-band ESR for comparisons in vitro. The spin probe was hexamethyl imidazolidine (HMI) with a pK of 4.6. All techniques detected HMI. Detection by FC-DNP implies coupling between the free radical and solvent water spins. Separations between the three spectral lines of the nitroxide radical, relative to measurement frequency, were consistent with theory. The overall spectrum width from unprotonated HMI (pH > pK) was greater than that from protonated agent (pH < pK). This was observed in vitro and in vivo. Longer-term studies showed that HMI is detectable and has the same spectral width (i.e., is at the same pH) up to 2 hr after gavage into the stomach, although the magnitude of the signal decreases rapidly during the first hour. These findings demonstrate the suitability of LODESR and FC-DNP for monitoring HMI and measuring pH in vivo. These techniques would be useful for monitoring disease and drug pharmacology in the living system.

  • 52.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Björklund, Glenn
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Heinonen, Ilkka
    Turku PET Centre, University of Turku, Finland.
    Kemppainen, Jukka
    Turku PET Centre, University of Turku, Finland.
    Knuuti, Juhani
    Turku PET Centre, University of Turku, Finland.
    Kyröläinen, Heikki
    University of Jyväskylä, Finland.
    Kalliokoski, Kari
    Turku PET Centre, University of Turku, Finland.
    Perfusion heterogeneity does not explain excess muscle oxygen uptake during variable intensity exercise2010In: Clinical Physiology and Functional Imaging, ISSN 1475-0961, E-ISSN 1475-097X, Vol. 30, no 4, p. 241-249Article in journal (Refereed)
    Abstract [en]

    The association between muscle oxygen uptake (VO2) and perfusion or perfusion heterogeneity (relative dispersion, RD) was studied in eight healthy male subjects during intermittent isometric (1 s on, 2 s off) one-legged knee-extension exercise at variable intensities using positron emission tomography and a-v blood sampling. Resistance during the first 6 min of exercise was 50% of maximal isometric voluntary contraction force (MVC) (HI-1), followed by 6 min at 10% MVC (LOW) and finishing with 6 min at 50% MVC (HI-2). Muscle perfusion and O2 delivery during HI-1 (26 ± 5 and 5·4 ± 1·0 ml 100 g−1 min−1) and HI-2 (28 ± 4 and 5·8 ± 0·7 ml 100 g−1 min−1) were similar, but both were higher (P<0·01) than during LOW (15 ± 3 and 3·0 ± 0·6 ml 100 g−1 min−1). Muscle VO2 was also higher during both HI workloads (HI-1 3·3 ± 0·4 and HI-2 4·1 ± 0·6 ml 100 g−1 min−1) than LOW (1·4 ± 0·4 ml 100 g−1 min−1; P<0·01) and 25% higher during HI-2 than HI-1 (P<0·05). O2 extraction was higher during HI workloads (HI-1 62 ± 7 and HI-2 70 ± 7%) than LOW (45 ± 8%; P<0·01). O2 extraction tended to be higher (P = 0·08) during HI-2 when compared to HI-1. Perfusion was less heterogeneous (P<0·05) during HI workloads when compared to LOW with no difference between HI workloads. Thus, during one-legged knee-extension exercise at variable intensities, skeletal muscle perfusion and O2 delivery are unchanged between high-intensity workloads, whereas muscle VO2 is increased during the second high-intensity workload. Perfusion heterogeneity cannot explain this discrepancy between O2 delivery and uptake. We propose that the excess muscle VO2 during the second high-intensity workload is derived from working muscle cells.

  • 53.
    Laaksonen, Marko
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Heinonen, Ilkka
    Turku PET Centre, University of Turku, Finland.
    Luotolahti, Matti
    University of Turku, Finland.
    Nuutila, Pirjo
    Turku PET Centre, University of Turku, Finland.
    Raitakari, Olli
    Turku PET Centre, University of Turku, Finland.
    Knuuti, Juhani
    Turku PET Centre, University of Turku, Finland.
    Kalliokoski, Kari
    Turku PET Centre, University of Turku, Finland.
    Left-ventricular hypertrophy associates to impaired maximal myocardial perfusion in endurance-trained men2009Conference paper (Refereed)
    Abstract [en]

    Long-term endurance training induces morphological adaptations in heart, such as left-ventricular (LV) hypertrophy caused by wall thickening and cavity enlargement. Interestingly, these anatomical changes in the heart are strikingly similar to certain pathophysiological changes (Pellicia 2000). Previous studies have shown that the perfusion response in myocardium during dipyridamole- or adenosine infusion is decreased in several pathophysiological states with LV hypertrophy (e.g. Stolen et al. 2004). However, studies in endurance athletes with LV hypertrophy have shown contradictory results on myocardial perfusion response ranging from reduced to increased myocardial perfusion during dipyridamole- or adenosine-induced vasodilation compared to untrained men (Kjaer et al. 2005; Kalliokoski et al. 2002). The degree of hypertrophy could explain the discrepant findings in studies in athletes, but it has not been thoroughly investigated. Thus, we examined totally 31 endurance athletes (ET) and 25 untrained (UT) men in order to study the association between myocardial functional and anatomical parameters measured with echocardiography, and myocardial perfusion (at rest and during maximal vasodilation induced by iv adenosine) measured with Positron Emission Tomography. Both VO2max (60+-5 vs 42+-8 ml/kg/min, p<0.001) and LVmass index (169+-27 vs 102+-15 g/m2, p<0.001) were markedly higher in ET. Resting myocardial perfusion was similar between the groups (ET 0.7+-0.2 vs UT 0.8+-0.2 ml/g/min, p=0.22) whereas adenosine-stimulated perfusion was lower in ET (2.9+-1.0 vs 3.7+-1.0 ml/g/min, p<0.01). VO2max correlated inversely with adenosine-stimulated perfusion in ET (r=-0.39, p=0.03) and with resting perfusion in UT (-0.49, p=0.01). Forward LV work correlated linearly with resting perfusion in both groups (ET r=0.54, p<0.01; UT r=0.50, p=0.01). ET group was further divided into three subgroups according to LVmass index (ET1: LVmass index <150g/m2, n=9; ET2 LVmass index 150-180 g/m2, n=12; ET3 LVmass index >180 gm2, n=10). Adenosine-induced myocardial perfusion decreased gradually when LVmass increased (UT 3.7+-1.+0 vs ET1 3.3+-0.9 vs ET2 2.7+-1.4 vs ET3 2.6+-0.5 mL g-1 min-1, p=0.008). LVmass index was also inversely related to adenosine-induced perfusion in entire study population (r=-0.46, p<0.01). Therefore, these results suggest that endurance training-induced severe cardiac hypertrophy impairs myocardial perfusion capacity.

    Kalliokoski K et al. (2002) Med Sci Sports Exerc 34:948-53

    Kjaer A et al. (2005) Am J Cardiol 96:1692-98

    Pellicia A (2000) Curr Cardiol Rep 2(2):166-71

    Stolen KQ et al (2004) 10(2):132-40

  • 54. Lindinger, Stefan J
    et al.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Mueller, Erich
    Rapp, Walter
    Changes in upper body muscle activity with increasing double poling velocities in elite cross-country skiing2009In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 106, no 3, p. 353-363Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to investigate whether the stretch-shortening cycle (SSC) contraction is integrated in neuromuscular activation in upper body muscles during double poling in cross-country skiing. Thirteen elite skiers performed double poling roller-skiing at increasing treadmill velocities of 9, 15, 21, 27 km h(-1) and their individual maximal velocity. Elbow angle, axial pole force and surface EMG in the triceps brachii, pectoralis major, latissimus dorsi and teres major muscle were recorded. Increases in peak pole force, rate of force development and elbow flexion angular velocities were identified (P < 0.05). The mean MVC-normalized EMG amplitudes increased during the pre-activation phase before pole plant, elbow flexion and the reflex-mediated phase between 30 and 120 ms after pole plant due to velocity increases (P < 0.05). It is thus suggested that elite cross-country skiers use SSC during double poling, particularly in the triceps muscle in order to generate high forces.

  • 55.
    Lodin-Sundström, Angelica
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Lunde, Alexander
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Palm, Oscar
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Nilsson, Simon
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Swedish Winter Sports Research Centre, Östersund, Sweden..
    Blood boosting by spleen contraction during exercise at different altitudes.2014Conference paper (Refereed)
    Abstract [en]

    Spleen contraction with release of erythrocytes improves human performance in hypoxic situations. Hypoxia and exercise are known to separately trigger the response. We studied the response to exercise at different altitudes during a two week ascent to 4200m. Eleven healthy lowlanders (five women; mean±SD age 26±3 years) did a modified Harvard step test at 1370, 3700 and 4200m altitude after 10 min rest. Spleen volume was measured via ultrasonic imaging and capillary hemoglobin (Hb) with Hemocue before and after tests. Mean(±SD) baseline spleen volume at 1370m was 250(±9)ml, after exercise it had been reduced to 207(±10)ml (P<0.01). At 3700m, baseline spleen volume was 230(±9)ml, after exercise 173(±10)ml (P<0.01). At 4200m baseline was 211(±10)ml, after exercise 158(±13)ml (P<0.05). Baseline Hb increased by altitude from 137.8(±3.8)g/L at 1370m, to 141.2(±2.3)g/L at 3700m and 151.4(±2.3)g/L at 4200m (P<0.01). At all locations Hb had increased after exercise; at 1370m by 7.2%, at 3700m by 6.2% and at 4200m by 3.2%. This suggests the spleen was already somewhat contracted during rest at higher altitudes, which was reflected by the progressively higher baseline Hb. Exercise initiated spleen contraction of similar magnitude at all altitudes, and post exercise values were progressively smaller with altitude. Hb was also elevated at all exercise tests, but not directly reflecting the spleen volume reductions, possibly due to differences in peak times. This study suggests that baseline spleen volume is affected by altitude which elevates Hb and that contraction after exercise results in further Hb elevation.

  • 56.
    Lodin-Sundström, Angelica
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Söderberg, Daniel
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Ekstam, Marcus
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Swedish Winter Sports Research Centre, Östersund, Sweden..
    Exercise at simulated altitude enhances spleen contraction2014Conference paper (Refereed)
  • 57.
    MARTIN-RINCON, M
    et al.
    University of Las Palmas, Spain.
    MORALES-ALAMO, D
    University of Las Palmas, Spain.
    PEREZ-LOPEZ, A
    University of Las Palmas, Spain.
    PEREZ-SUAREZ, I
    University of Las Palmas, Spain.
    STRÖM, K
    Diabetes and Endocrinology, Department of Clinical Sciences, Lund University Diabetes Centre, Lund University, Malmö, Sweden.
    CALBET, JAL
    University of Las Palmas, Spain.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    HANSSON, O
    Diabetes and Endocrinology, Department of Clinical Sciences, Lund University Diabetes Centre, Lund University, Malmö, Sweden.
    Upregulation of nicotinamide n-methyltransferase in skeletal muscle following prolongedexercise and caloric restriction2017In: 22nd Annual Congress of the European College of Sport Science / [ed] Ferrauti, A., Platen, P., Grimminger-Seidensticker, E., Jaitner, T.,, Cologne, Germany: DTP Publishing, 2017, p. 186-, article id MO-PM03Conference paper (Refereed)
    Abstract [en]

    Introduction

    Expression of Nicotinamide (NA) N-methyltransferase (NNMT), the enzyme responsible for the methylation of NA to methylnicotinamide (MNA), is reduced in obese and diabetic mice. In rodent liver, NNMT activity and plasma MNA levels are increased after 90min of swimming.

    NNMT knockdown in mice white adipose tissue increases energy expenditure, suggesting a protective role against diet-induced obesity and type-2 diabetes. The role that NNMT plays in human metabolism remains unknown. Thus, the aims of the study were 1) to determine in human skeletal muscle (sm) whether NNMT is upregulated by prolonged exercise and 2) to ascertain whether the expression of NNMT in sm is influenced by severe energy deficit.

    Methods

    Fifteen overweight men underwent to 4 days of caloric restriction (CR) (0.8 g/kg BW/day) in combination with prolonged exercise (PE) (8h walking + 45min single-arm cranking/day). Three sm biopsies (exercised/non exercised arm and one leg) were obtained before (PRE), after (PE+CR) and following 3 days of control diet (isoenergetic) and reduced exercise (CD) to measure the expression of key metabolic genes (e.g. PDK4, CPT2, PFKFB3, NNMT) (microarray), NNMT protein expression (WB) and circulating plasma MNA levels (LC-MS). Maximal fat oxidation (MFO) (indirect calorimetry) and body composition (DEXA) were measured. ANOVA repeated-measures was used.

    Results

    During PE+CR the energy deficit was 5000 kcal/d reducing fat mass by 2.8 (PE+CR) and 3.8 kg (CD). MFO was increased. CPT2, PDK4, PFKFB3 genes (CHO-to-fat metabolic shift) were differentially expressed (FDR<5%) in at least one sm. Compared to PRE, after CD, NNMT gene expression was upregulated in all sm (~3-5 fold). Protein NNMT increased ~13-fold (p<0.001), ~9-fold (p<0.01) and ~5-fold (p<0.001) for non-exercised and exercised arm (45min/day) and leg (8h/day), respectively. Circulating levels of MNA were augmented two-fold. The increase in NNMT expression from PRE to CD was associated with the increase in MFO (r=0.37, p=0.01,n=45).

    Discussion

    This findings reveal that NNMT is upregulated in human sm in response to a severe energy deficit, with a simultaneous increase of MNA plasma levels. However, this response was attenuated in the exercised sm. NNMT may have a role in facilitating fat oxidation. Caloric restriction elicits increased sirtuins expression and activity, coupled with the NAD+ breakdown into NA. Overexpression of NNMT probably prevents accumulation of NA, which would otherwise inhibit the sirtuins. Our data suggest sm as a plausible source of MNA, which may act as a myokine with a role in the adaptation to starvation.

  • 58.
    Morales-Alamo, D
    et al.
    University of Las Palmas, Spain.
    Martín-Rincón, M
    University of Las Palmas, Spain.
    Azzinnari, M
    Pérez-Suárez, I
    University of Las Palmas, Spain.
    Said, M
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Calbet, JAL
    University of Las Palmas, Spain.
    Severe caloric restriction elicits NF-k beta signalling in human skeletal muscle: influenceof exercise and protein content in the diet2017In: 22nd Annual Congress of the European College of Sport Science / [ed] Ferrauti, A., Platen, P., Grimminger-Seidensticker, E., Jaitner, T., Bartmus, U., Becher, L.,, Cologne, Germany: DTP Publishing, 2017, p. 501-, article id OP-PM46Conference paper (Refereed)
  • 59.
    Mourot, Laurent
    et al.
    Univ Franche Comte, F-25030 Besancon, France.
    Fabre, Nicolas
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Savoldelli, Aldo
    Univ Verona, Ctr Res Mt Sport & Hlth, Rovereto, Italy.
    Schena, Federico
    Univ Verona, Ctr Res Mt Sport & Hlth, Rovereto, Italy.
    Second Ventilatory Threshold From Heart-Rate Variability: Valid When the Upper Body Is Involved?2014In: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 9, no 4, p. 695-701Article in journal (Refereed)
    Abstract [en]

    To determine the most accurate method based on spectral analysis of heart-rate variability (SA-HRV) during an incremental and continuous maximal test involving the upper body, the authors tested 4 different methods to obtain the heart rate (HR) at the second ventilatory threshold (VT2). Sixteen ski mountaineers (mean +/- SD; age 25 +/- 3 y, height 177 +/- 8 cm, mass 69 +/- 10 kg) performed a roller-ski test on a treadmill. Respiratory variables and HR were continuously recorded, and the 4 SA-HRV methods were compared with the gas-exchange method through Bland and Altman analyses. The best method was the one based on a time-varying spectral analysis with high frequency ranging from 0.15 Hz to a cutoff point relative to the individual's respiratory sinus arrhythmia. The HR values were significantly correlated (r(2) = .903), with a mean HR difference with the respiratory method of 0.1 +/- 3.0 beats/min and low limits of agreements (around -6 /+ 6 beats/min). The 3 other methods led to larger errors and lower agreements (up to 5 beats/min and around -23/+ 20 beats/min). It is possible to accurately determine VT2 with an HR monitor during an incremental test involving the upper body if the appropriate HRV method is used.

  • 60.
    Nielsen, Joachim
    et al.
    Department of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC), University of Southern Denmark, Odense M, DK-5230, Denmark .
    Cheng, Arthur J.
    Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77, Stockholm, Sweden .
    Ørtenblad, Niels
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Department of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC), University of Southern Denmark, Odense M, DK-5230, Denmark .
    Westerblad, Håkan
    Department of Physiology and Pharmacology, Karolinska Institutet, SE-171 77, Stockholm, Sweden .
    Subcellular distribution of glycogen and decreased tetanic Ca2+ in fatigued single intact mouse muscle fibres2014In: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 592, no 9, p. 2003-2012Article in journal (Refereed)
    Abstract [en]

    Key points Muscle glycogen (the storage form of glucose) is consumed during muscle work and the depletion of glycogen is thought to be a main contributor to muscle fatigue. In this study, we used a novel approach to first measure fatigue-induced reductions in force and tetanic Ca2+ in isolated single mouse muscle fibres following repeated contractions and subsequently quantify the subcellular distribution of glycogen in the same fibre. Using this approach, we investigated whether the decreased tetanic Ca2+ induced by repeated contractions was associated with glycogen depletion in certain subcellular regions. The results show a positive correlation between depletion of glycogen located within the myofibrils and low tetanic Ca2+ after repetitive stimulation. We conclude that subcellular glycogen depletion has a central role in the decrease in tetanic Ca2+ that occurs during repetitive contractions. In skeletal muscle fibres, glycogen has been shown to be stored at different subcellular locations: (i) between the myofibrils (intermyofibrillar); (ii) within the myofibrils (intramyofibrillar); and (iii) subsarcolemmal. Of these, intramyofibrillar glycogen has been implied as a critical regulator of sarcoplasmic reticulum Ca2+ release. The aim of the present study was to test directly how the decrease in cytoplasmic free Ca2+ ([Ca2+](i)) during repeated tetanic contractions relates to the subcellular glycogen distribution. Single fibres of mouse flexor digitorum brevis muscles were fatigued with 70Hz, 350ms tetani given at 2s (high-intensity fatigue, HIF) or 10s (low-intensity fatigue, LIF) intervals, while force and [Ca2+](i) were measured. Stimulation continued until force decreased to 30% of its initial value. Fibres were then prepared for analyses of subcellular glycogen distribution by transmission electron microscopy. At fatigue, tetanic [Ca2+](i) was reduced to 70 +/- 4% and 54 +/- 4% of the initial in HIF (P<0.01, n=9) and LIF (P<0.01, n=5) fibres, respectively. At fatigue, the mean inter- and intramyofibrillar glycogen content was 60-75% lower than in rested control fibres (P<0.05), whereas subsarcolemmal glycogen was similar to control. Individual fibres showed a good correlation between the fatigue-induced decrease in tetanic [Ca2+](i) and the reduction in intermyofibrillar (P=0.051) and intramyofibrillar (P=0.0008) glycogen. In conclusion, the fatigue-induced decrease in tetanic [Ca2+](i), and hence force, is accompanied by major reductions in inter- and intramyofibrillar glycogen. The stronger correlation between decreased tetanic [Ca2+](i) and reduced intramyofibrillar glycogen implies that sarcoplasmic reticulum Ca2+ release critically depends on energy supply from the intramyofibrillar glycogen pool.

  • 61.
    Nielsen, Joachim
    et al.
    Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.
    Holmberg, H.-C.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Schrøder, H. D.
    Clinical Institute, University of Southern Denmark, Odense, Denmark .
    Saltin, B.
    Copenhagen Muscle Research Centre, Copenhagen, Denmark.
    Ørtenblad, N.
    Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark.
    Subcellular localization dependent usage of skeletal muscle glycogen during 1 hr cross country skiing2010In: Proceedings for the XXXIX European Muscle Conference (EMC 2010), 2010Conference paper (Refereed)
  • 62. Ortenblad, Niels
    et al.
    Nielsen, Joachim
    Saltin, Bengt
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Glycogen has a structural role in maintaining normal EC coupling in elite cross-country skiers, by modulating SR Ca2+ release rate.2008In: The Integrative Biology of Exercise - V, 2008, p. 29.3-Conference paper (Refereed)
  • 63. Oskolov, Nikolay
    et al.
    Ström, Kristoffer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. LUDC, Lunds Universitet.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Hansson, Ola
    GWAS OF HISTOLOGICAL PHENOTYPES PROVIDES INSIGHTS INTO THE GENETIC ARCHITECTURE OF HUMAN SKELETAL MUSCLE2015In: ABSTRACT BOOK for the SGGD 2015, 2015Conference paper (Refereed)
    Abstract [en]

    Introduction

    Athlete performance depends to some extent on skeletal muscle fiber-type composition, i.e. athletes practicing endurance sports usually have a higher proportion of slow-twitch type I fibers, while fast-twitch type II fibers are more common for athletes in explosive sports. Insulin sensitivity has also been correlated with proportion of type I fibers, i.e. insulin resistant individuals having reduced muscle oxidative capacity with less oxidative type I and more glycolytic type IIx fibers.

    Aims

    Here we aimed to identify genetic variation and corresponding biological mechanisms affecting human skeletal muscle histology.

    Methods

    We performed a genome-wide association meta-analysis in Swedish males from 3 independent cohorts (n=656) with skeletal muscle histological phenotypes, e.g. capillary density, fibre-type distribution and area (measured by ATPas staining). Skeletal muscle microarray expression data (n=77) were used for an eQTL analysis of associated markers. Follow-up of capillary density was done in Swedish elite cross-country skiers (n=15).

    Results

    We identified 11 genome-wide significant (p<5x10-8) independent loci (STEAP, NYAP2, ADRA1B, TNFSF11, FAM155A, SLC22A10, FASLG, RBFOX1, FOXJ2, KCNMA1, RAB3GAP2) associated with 6 skeletal muscle phenotypes. eQTL-genes corresponding to the top associated variants were enriched in metabolic pathways. Using a population differentiation neutrality test we show that some of the fibre-type nominally associated loci (p<1x10-6) fall within regions of positive selection (i.e. FHIT, CRISP and ANXA1). The G-allele of rs115660502 (MAF=0.048) was significantly associated (p=2x10-8) with increased capillary density and also decreased expression of the nearby gene RAB3GAP2 (FDR=0.007). The G-allele also had a significantly higher frequency (MAF=0.122, p=0.029) in the cohort of Swedish elite skiers.

    Conclusion

    Our results add to our understanding of skeletal muscle architecture and indicate that there is a genetic component to it and that this might contribute to increased endurance performance in sport athletes.

  • 64.
    Patrician, Alexander
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Engan, Harald
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Lundsten, David
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Effects of Dietary Nitrate on Sleep at Altitude2014Conference paper (Refereed)
  • 65.
    Patrician, Alexander
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Schagatay, Erika
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Dietary nitrate reduces oxygen cost for dynamic apnea2014Conference paper (Refereed)
  • 66. Ponce-González, JG
    et al.
    de Torres-Peralta, RS
    Pérez, I
    Feijoó, D
    Lindblom, Hampus
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Holmberg, H-C
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Calbet, J
    Dehydration after prolonged exercise combined with severe     caloric restriction despite drinking ad libitum2011Conference paper (Refereed)
  • 67.
    PONCE-GONZÁLEZ, JG
    et al.
    University of Las Palmas de Gran Canaria, Spain.
    MALDONADO-MARTÍNEZ, E
    University of Las Palmas de Gran Canaria, Spain.
    LOSA-REYNA, J
    University of Las Palmas de Gran Canaria, Spain.
    DE LA CALLE-HERRERO, J
    University of Las Palmas de Gran Canaria, Spain.
    PEREZ-SUAREZ, I
    University of Las Palmas de Gran Canaria, Spain.
    SANTANA, A
    University of Las Palmas de Gran Canaria, Spain.
    GUADALUPE-GRAU, A
    University of Las Palmas de Gran Canaria, Spain.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    CALBET, JAL
    University of Las Palmas de Gran Canaria, Spain.
    PRESERVATION OF FAT-FREE MASS UNDER CONDITIONS OF SEVERE ENERGY DEFICIT BY EXERCISE: AN STAT3-MEDIATED PHENOMENON?2014In: Proceedings for the 19th ECSS, Amsterdam, The Netherlands, 2014Conference paper (Refereed)
  • 68.
    PÉREZ-SUÁREZ, I
    et al.
    University of Las Palmas, Gran Canaria, Spain.
    CALLE-HERRERO, J
    University of Las Palmas, Gran Canaria, Spain.
    PONCE-GONZÁLEZ, JG
    University of Las Palmas, Gran Canaria, Spain.
    LOSA-REYNA, J
    University of Las Palmas, Gran Canaria, Spain.
    SANTANA, A
    University of Las Palmas, Gran Canaria, Spain.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    CALBET, JAL
    University of Las Palmas, Gran Canaria, Spain.
    LEPTIN RECEPTOR MOLECULAR VARIANTS ARE DIFFERENTLY REGULATED BY EXERCISE AND ENERGY DEFICIT IN HUMAN SKELETAL MUSCLE2014Conference paper (Refereed)
    Abstract [en]

    Introduction

    Leptin signals in skeletal muscles through pathways which share some steps with the insulin and IGF1. We have recently shown that LEPR (OBR-170) is increased in the dominant arm of tennis players 1 and is reduced in deltoid and vastus lateralis (VL) of obese compared to control subjects 2. The aim of this study was to determine whether exercise up-regulates the protein abundance and phosphorylation status of the different molecular variations of the LEPR (OBR-170, 128, 98A or 98B) in human skeletal muscle. We hypothesized that exercise will up-regulate leptin signaling in skeletal muscle.

     

    Methods

    Fifteen overweight men underwent three experimental phases: pre-test (PRE); caloric restriction (3.2 Kcal/kg body Wt/d) + exercise (45min unilateral arm cranking/d + 8h walking/d) for 4 days (CRE); and control isoenergetic diet + reduced exercise for 3 days (CD). During CRE, the diet consisted solely of whey protein (PRO, n=8) or sucrose (SU, n=7) (0.8 g/kg body Wt/d). Muscle biopsies (135 biopsies in all) were obtained from the trained and untrained deltoid, and VL, after 12h fast at PRE, and end of CRE and CD. The molecular variants of LEPR (OBR-170, 128, 98A and 98B) were determined by western blot and LEPR mRNA by PCR.

      

    Results

    Serum leptin was reduced by ~60% following CRE and CD (P<0.05). LEPRs were more abundant in arm than leg muscles. LEPR mRNA was increased in exercised muscles after CRE. OBR-170 was reduced after CRE and CD only in the control arm (P<0.05). OBR-128 was increased after CD in exercised extremities (P<0.05). OBR-98A was increased after CRE in trained arm, and after CD in legs (P<0.05). However, OBR-98B was increased after CRE and CD in both arms and exercised extremities (P<0.05), being these effects more pronounced in the PRO group (P<0.05). After CD, LEPR mRNA returned to basal levels while LEPR expression was increased in all muscles (P<0.05). The fraction of LEPR activated (Tyr1141 phosphorylated) was reduced in arms but not in leg muscles. LEPR phosphorylation was correlated with JAK2 (upstream) and STAT3 (downstream) phosphorylation (r=0.67-0.89, P<0.05).

     

    Discussion

    Caloric restriction seems to reduce the abundance of LEPR, but this effect varies depending on specific molecular variants of the receptor. The reduction of LEPR is partly counteracted by exercise, likely contributing to increase muscle leptin sensitivity. Whey protein ingestion facilitates these effects. Resuming normal food ingestion after a period of severe energy deficit is accompanied by increased expression LEPR in skeletal muscle. 

  • 69.
    Radom-Aizik, Shlomit
    et al.
    Univ Calif Irvine, Irvine, CA USA .
    Haddad, Fadia
    Univ Calif Irvine, Irvine, CA USA .
    Owerkowicz, Tomasz
    Calif State Univ San Bernardino, San Bernardino, CA 92407 USA .
    Devaney, Joseph M.
    George Washington Univ, Children Natl Med Ctr, Washington, DC USA .
    Hoffman, Eric P.
    George Washington Univ, Children Natl Med Ctr, Washington, DC USA .
    Tesch, Per A.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Adams, Gregory R.
    Univ Calif Irvine, Irvine, CA USA .
    DNA Methylation is Altered in Human Skeletal Muscle in Response to Exercise Training2012In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 44, no Suppl 2, p. 348-348Article in journal (Other academic)
  • 70. Richardson, M
    et al.
    de Bruijn, Robert
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Haughey, Helena
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Andersson, J
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    The incidence of hematocrit increase during apnea in non divers: European Underwater and Baromedical Society (EUBS) meeting Copenhagen, Denmark2003Conference paper (Other academic)
  • 71.
    Richardson, Matt
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Engan, Harald
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Lodin-Sundström, Angelica
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Effect of hypercapnia on spleen-related haemoglobin increase during apnea2012In: Diving and Hyperbaric Medicine, ISSN 1833-3516, Vol. 42, no 1, p. 4-9Article in journal (Refereed)
    Abstract [en]

    BACKGROUND:

    Splenic contraction associated with apnea causes increased haemoglobin concentration and haematocrit (Hct), an effect that may promote prolonged breath-holding. Hypoxia has been shown to augment this effect, but hypercapnic influences have not been investigated previously.

    METHODS:

    Eight non-divers performed three series of apneas on separate days after inspiration of oxygen with different carbon dioxide (CO₂) levels. Each series consisted of three apneas 2 minutes apart: one with pre-breathing of 5% CO₂ in oxygen (O₂, 'Hypercapnia'); one with pre-breathing of 100% O₂ ('Normocapnia'); and one with hyperventilation of 100% O₂ ('Hypocapnia'). The apnea durations were repeated identically in all trials, determined from the maximum duration attained in the CO₂ trial. A fourth trial, breathing 5% CO₂ in O₂ for the same duration as these apneas was also performed ('Eupneic hypercapnia'). In three subjects, spleen size was measured using ultrasonic imaging.

    RESULTS:

    Haemoglobin increased by 4% after apneas in the 'Hypercapnia' trial (P = 0.002) and by 3% in the 'Normocapnia' trial (P = 0.011), while the 'Hypocapnia' and 'Eupneic hypercapnia' trials showed no changes. The 'easy' phase of apnea, i.e., the period without involuntary breathing movements, was longest in the 'Hypocapnia' trial and shortest in the 'Hypercapnia' trial. A decrease in spleen size was evident in the hypercapnic trial, whereas in the hypocapnia trial spleen size increased, while only minor changes occurred in the other trials. No differences were observed between trials in the cardiovascular diving response.

    CONCLUSION:

    There appears to be a dose-response effect of CO₂ on triggering splenic contraction during apnea in the absence of hypoxia.

  • 72.
    Richardson, Matt
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Lodin, Angelica
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Engan, Harald
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Hypercapnia moderates hemoglobin increases during apneaManuscript (Other academic)
  • 73.
    Richardson, Matt X.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences, Engineering and Mathematics.
    Hematological changes arising from spleen contraction during apnea and altitude in humans2008Doctoral thesis, comprehensive summary (Other academic)
  • 74.
    Richardson, Matthew
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    de Bruijn, Robert
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Pettersson, Sofia
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Reimers, J.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    CORRELATION BETWEEN SPLEEN SIZE AND HEMATOCRIT DURING APNEA IN HUMANS2006In: Proceedings of the Undersea and Hyperbaric Medical Society/Divers Alert Network 2006 June 20-21 Workshop. Durham, NC, 2006Conference paper (Other academic)
  • 75.
    Rodríguez-Zamora, Lara
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering. Institut Nacional d’Educació Física de Catalunya, Universitat de Barcelona, Barcelona, Spain..
    Engan, Harald K
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering. LHL Health Röros, The Norwegian Heart and Lung Patient Organization, Norway..
    Lodin-Sundström, Angelica
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Iglesias, Xavier
    Institut Nacional d’Educació Física de Catalunya, Universitat de Barcelona, Barcelona, Spain.
    Rodríguez, Ferran A
    Institut Nacional d’Educació Física de Catalunya, Universitat de Barcelona, Barcelona, Spain.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering. Swedish Winter Sports Research Centre, Östersund, Sweden..
    Blood lactate after competitive free diving and synchronized swimming events2013Conference paper (Refereed)
  • 76.
    Rodríguez-Zamora, Lara
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering. Institut Nacional d’Educació Física de Catalunya, Universitat de Barcelona, Barcelona, Spain..
    Engan, Harald K
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering. LHL Health Röros, The Norwegian Heart and Lung Patient Organization, Norway..
    Lodin-Sundström, Angelica
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Iglesias, Xavier
    Institut Nacional d’Educació Física de Catalunya, Universitat de Barcelona, Barcelona, Spain.
    Rodríguez, Ferran A
    Institut Nacional d’Educació Física de Catalunya, Universitat de Barcelona, Barcelona, Spain.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Blood lactate after competitive free diving and synchronized swimming eventsManuscript (preprint) (Other academic)
  • 77.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Andningstekniker inom avancerad fridykning: Vad är 'yogaandning', 'lungpackning' och 'hook breathing', och när används de?2012In: Sportdykaren, ISSN 0038-7967, Vol. 2Article in journal (Other (popular science, discussion, etc.))
  • 78.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Diving response and spleen contraction – two ways of shifting to a diving mode. : Tunisian Federation of Diving (FAST), Bizerte, Tunisia2003Conference paper (Other scientific)
  • 79.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Effects of water and ambient air temperatures on human diving bradycardia.1996In: European Journal of Applied Physiology, ISSN 1439-6319, Vol. 73, no 1/2, p. 1-6Article in journal (Refereed)
    Abstract [en]

    Upon apnoeic face immersion, humans develop a diving response resembling that found in diving mammals. There have been contradictory reports regarding the influence of water temperature on the magnitude of the resulting bradycardia. This study examined the influence of both water and ambient air temperatures on human diving bradycardia. A group of 23 volunteers performed three series of apnoeic episodes after 60-min exposure to air at temperatures of 10, 20 or 30°C. Oral and skin temperatures were measured during this exposure and during the subsequent test on 5 subjects. At 20°C air temperature oral and skin temperatures were measured on 10 subjects. Heart rate (HR) was recorded for the 23 subjects during apnoea in air and apnoea with the face immersed in water of 10, 20 or 30°C, at each air temperature. We found that both air and water temperatures had significant effects on immersion bradycardia, but in opposite directions. Face immersion in cold water after exposure to a high ambient air temperature induced the most pronounced bradycardia. We further observed that exposure to different ambient air temperatures resulted in different patterns of HR response to water temperature. The range in which the response was positively correlated to water temperature differed at 30°C ambient air from that at 10 and 20°C ambient air. We concluded from these studies that human bradycardia resulting from apnoeic face immersion is inversely proportional to water temperature within a range which is determined by the ambient air temperature. Thus, the interval in which the response to cold stimulation varies with temperature, would appear to be determined by the ambient temperature before stimulation

  • 80.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    How to dive to 100 m on one breath2012Conference paper (Other academic)
  • 81.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Human physiology of breath-hold diving2012Conference paper (Other academic)
  • 82.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Human sexual dimorphism1991In: The Aquatic Ape: Fact or Fiction: the first scientific evaluation of a controversial theory of human evolution, London: Souvenir Press , 1991, p. 299-305Chapter in book (Other scientific)
    Abstract

  • 83.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Is the human diving response an adaptation to diving? 1996In: Bulletin de Medecine Subaquatique et Hyperbare, ISSN 1248-2846, no 6, p. 109-122Article in journal (Other scientific)
  • 84.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Lung volume and diving performance in breath-holding deep divers2011Conference paper (Other academic)
  • 85.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Lung volume and diving performance in breath-holding deep divers.2011Conference paper (Other academic)
  • 86.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    On One Breath of Air: Free Divers Physiology2012Conference paper (Other academic)
  • 87.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Review: Predicting performance in competive apnoea diving, part I: static apnoea2009In: Diving and Hyperbaric Medicine, ISSN 1833-3516, Vol. 39, no 2, p. 88-99Article, review/survey (Refereed)
    Abstract [en]

    Ever since the first deep diving competitions were organized, there has been debate about when the ultimate limits of human apnoeic performance will be reached, and which factors will determine these limits. Divers have thus far surpassed all former predictions by physiologists in depth and time. The common factor for all competitive apnoea disciplines is apnoeic duration, which can be prolonged by any means that increase total gas storage or tolerance to asphyxia, or reduce metabolic rate. These main factors can be broken down further into several physiological or psychophysiological factors, which are identified in this review. Like in other sports, the main aim in competitive apnoea is to extend human performance beyond the known limits. While a beginner may extend apnoeic duration by getting closer to his or her personal limit, the elite diver can only extend the duration further by pushing the individual physiological limit further by training. In order to achieve this, it is essential to identify the performance predicting factors of apnoea sports and which factors can be affected by training, work that has only just begun. This is the first of two papers reviewing the main factors predicting performance in competitive apnoea diving, which focuses on static apnoea, while the following paper will review dynamic distance and depth disciplines. Great improvements have been made in all diving disciplines in recent years and the 10-minute barrier in resting 'static apnoea' has been broached. Despite this, current training methods and the strategies employed suggest that duration can be prolonged still further, and divers themselves suggest the ultimate limit will be 15 minutes, which appears physiologically possible, for example, with further development of techniques to reduce metabolic rate.

  • 88.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    The human diving response - effects of temperature and training.1996Doctoral thesis, monograph (Other scientific)
  • 89.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    The second crisis1991In: The aquatic ape: Fact or fiction?, 1991, p. 296-299Chapter in book (Other academic)
    Abstract [en]

    Schagatay E, (1991) In: "The aquatic ape: Fact or fiction?", M Roede, J Wind, J Patrick, V Reynolds (eds) Souvenir Press, London, p 296-299.

  • 90.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    The significance of the human diving reflex1991In: The Aquatic Ape: Fact or Fiction: the first scientific evaluation of a controversial theory of human evolution, London: Souvenir Press , 1991, p. 247-254Chapter in book (Other scientific)
    Abstract [en]

    Schagatay E (1991) The significance of the human diving reflex.

  • 91.
    Schagatay, Erika
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Vad är "Blow – tap – talk": hur gör man och vad används det till?2012In: Sportdykaren, ISSN 0038-7967, no 1Article in journal (Other (popular science, discussion, etc.))
  • 92.
    Schagatay, Erika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Andersson, Johan
    Department of Animal Physiology, Lund University.
    Hallén, Magnus
    Department of Surgery, Lund University Hospital, S-221 85 Lund.
    Pålsson, Birger
    Department of Surgery, Lund University Hospital, S-221 85 Lund.
    Selected Contribution: Role of spleen emptying in prolonging apneas in humans2001In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 90, no 4, p. 1623-1629Article in journal (Refereed)
    Abstract [en]

    This study addressed the interaction between short-term adaptation to apneas with face immersion and erythrocyte release from the spleen. Twenty healthy volunteers, including ten splenectomized subjects, participated. After prone rest, they performed five maximal-duration apneas with face immersion in 10°C water, with 2-min intervals. Cardiorespiratory parameters and venous blood samples were collected. In subjects with spleens, hematocrit and hemoglobin concentration increased by 6.4% and 3.3%, respectively, over the serial apneas and returned to baseline 10 min after the series. A delay of the physiological breaking point of apnea, by 30.5% (17 s), was seen only in this group. These parameters did not change in the splenectomized group. Plasma protein concentration, preapneic alveolar PCO2, inspired lung volume, and diving bradycardia remained unchanged throughout the series in both groups. Serial apneas thus triggered the hematological changes that have been previously observed after long apneic diving shifts; they were rapidly reversed and did not occur in splenectomized subjects. This suggests that splenic contraction occurs in humans as a part of the diving response and may prolong repeated apneas.

  • 93.
    Schagatay, Erika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    de Bruijn, Robert
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Richardson, Matthew
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Increase in hematocrit after short and long term apnea training2005In: Blue 2005. Human Behaviour and Limits in Underwater Environments. Abstract book: International Conference organised by: CNR Institute of Clinical Physiology, Pisa - Italy Apnea Academy - Italy University of Chieti - Italy. Pisa December 1-4 2005., Pisa: CNR Institute of Clinical Physiology , 2005, p. 57-58Conference paper (Refereed)
  • 94.
    Schagatay, Erika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Haughey, Helena
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Reimers, J
    Spleen volume changes evoked by serial apneas: Underwater and Baromedical Society (EUBS) meeting Copenhagen2003Conference paper (Other academic)
  • 95.
    Schagatay, Erika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Johansson, Orio
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Engan, Harald
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Lodin-Sundström, Angelica
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Training effects in human breath-hold diving2012Conference paper (Other academic)
  • 96.
    Schagatay, Erika
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Lodin-Sundström, Angelica
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Fasting improves static apnea performance in elite divers without enhanced risk of syncope2014In: European Journal of Sport Science, ISSN 1746-1391, E-ISSN 1536-7290, Vol. 14, no Suppl 1, p. S157-S164Article in journal (Refereed)
    Abstract [en]

    In competitive apnea divers, the nutritional demands may be essentially different from those of, for example, endurance athletes, where energy resources need to be maximised for successful performance. In competitive apnea, the goal is instead to limit metabolism, as the length of the sustainable apneic period will depend to a great extent on minimising oxygen consumption. Many but not all elite divers fast before performing static apnea in competition. This may increase oxygen consumption as mainly lipid stores are metabolised but could also have beneficial effects on apneic duration. Our aim was to determine the effect of over-night fasting on apnea performance. Six female and seven male divers performed a series of three apneas after eating and fasting, respectively. The series consisted of two 2-min apneas spaced by 3 min rest and, after 5 min rest, one maximal effort apnea. Apneas were performed at supine rest and preceded by normal respiration and maximal inspiration. Mean (±SD) time since eating was 13 h (±2 h 43 min) for the fasting and 1 h 34 min (±33 min) for the eating condition (P < 0.001). Mean blood glucose was 5.1 (±0.4) mmol/L after fasting and 5.9 (±0.7) mmol/L after eating (P<0.01). Lung volumes were similar in both conditions (NS). For the 2-min apneas, nadir SaO2 during fasting was 95 (±1)% and 92 (±2)% (P < 0.001) on eating and ETCO2 was lower in the fasting condition (P < 0.01) while heart rate (HR) during apnea was 74 (±10) bpm for fasting and 80 (±10) bpm for eating conditions (P < 0.01). Maximal apnea durations were 4 min 41 s (±43 s) during fasting and 3 min 51 s (±37 s) after eating (P < 0.001), and time without respiratory contractions was 31 s (25%) longer after fasting (P < 0.01). At maximal apnea termination, SaO2 and ETCO2 were similar in both conditions (NS) and apneic HR was 63 (±9) bpm for fasting and 70 (±10) bpm for eating (P < 0.01). The 22% longer apnea duration after fasting with analogous end apnea SaO2 levels suggests that fasting is beneficial for static apnea performance in elite divers, likely via metabolism-limiting mechanisms. The oxygen-conserving effect of the more pronounced diving response and possibly other metabolism-limiting mechanisms related to fasting apparently outweigh the enhanced oxygen consumption caused by lipid metabolism.

  • 97.
    Schagatay, Erika
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Nilsson, Simon
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Palm, Oscar
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Lunde, Alexander
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Lodin-Sundström, Angelica
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Ecotechnology and Sustainable Building Engineering.
    Can the cardiorespiratory response to exercise at altitude predict sensitivity to AMS?2014Conference paper (Refereed)
  • 98.
    Schagatay, Erika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Richardson, Matt
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Lodin, Angelica
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering and Sustainable Development.
    Spleen and lung volumes correlate with performance in elite apnea diversManuscript (Other academic)
  • 99.
    Schagatay, Erika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    van Kampen, M
    Apneic snout immersion in trained pigs elicits a "diving response". 1995In: Advances in Experimental Medicine and Biology, ISSN 0065-2598, Vol. 393, p. 73-76Article in journal (Refereed)
  • 100.
    Schagatay, Erika
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Engineering, Physics and Mathematics.
    van Kampen, M
    Andersson, Johan
    Effects of repeated apneas on apneic time and diving response in non-divers. 1998In: Undersea and Hyperbaric Medicine, ISSN 1066-2936, no 26, p. 143-149Article in journal (Refereed)
123 51 - 100 of 115
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