The effect of creatine and glycerol induced hyperhydration on running economy in moderate and hot environmental conditions

The primary objective of this study was to investigate the effects of a hyperhydration strategy on running economy in cool and hot conditions. The hyperhydration regimen consisted of a combination of Creatine and glycerol which previously has been shown to each have a hyperhydrating effect and if applied together this effect is additive. Seven well-trained athletes were invited to participate in this study which included a pre- and post-supplementation experimental trial consisting of running at an intensity of 60% VO2max for 30 minutes in moderate (Ta = 10.5 ± 0.2 °C; RH = 72.0 ± 1.1%) and another 30 minutes in hot (Ta = 34.72 ± 0.19 °C and RH = 71.5 ± 0.9%) conditions with a 30 min break in between during which subjects were given water to replace any fluid lost in the first part of the trial. Between the last two experiments subjects followed a seven-day supplementation regime, i.e. consuming a daily dose of 11.4 g of Cr∙H2O (equivalent to 10g of Creatine) and one dose of glycerol (1g•kg-1 BM) on the day of the final experiment. The measurements of total body water (TBW) indicated that not all subjects responded to the hyperhydration regimen. Hence, only the subjects considered responders were taken into analysis (n=7). In this group of subjects we found an increase of 0.8 ± .0.3 kg in BM, 0.64 ± 0.18 L in TBW of which 0.20 ± 0.12 L could be assigned to an increase in extracellular water (ECW), and 0.44 ± 0.09 L were due to an increase in intracellular water (ICW). No significant changes could be observed in thermoregulatory (core body temperature), cardiovascular (heart rate) or pulmonary responses (O2 consumption, CO2 production, minute ventilation, respiratory exchange ratio), and rating of perceived exertion. Nevertheless, in the trial after the supplementation the subjective perception of heat, i.e. thermal comfort, was significantly reduced after 5 and 10 minutes in the bout at 35°C. As no change in VO2 could be observed, we conclude that there is no negative impact of a slightly increased body weight on oxygen consumption. Compared to previous studies, this study could not achieve a hyperhydration sufficient enough to observe positive thermoregulatory and cardiovascular responses as reported by other studies investigating water pre-loading. These differences are possibly due to a change in the administration protocol of glycerol

The Effects of Lactate on Skeletal Muscle

Regular exercise and physical activity are cornerstones in the prevention and treatment of numerous chronic conditions, such as type 2 diabetes, coronary heart disease, and age-related sarcopenia. The associated health benefits arise from a number of tissues but due to its high plasticity skeletal muscle plays a pivotal role. The resident stem cells of skeletal muscle tissue, so called Satellite cells (SCs), contribute significantly to skeletal muscle adaptation and hence, maintenance of healthy tissue. The specific stimuli regulating SC development, i.e. activation, proliferation, an differentiation, depend on the form of exercise and consist of hormonal, mechanical, and metabolic signals. While hormonal and mechanical factors have been well documented, the importance of metabolic stimuli such as Lactate (La) remains less clear. La is produced continuously under aerobic conditions, but elevated levels occur during exercise when glycolysis is increased. La is able to induce muscle adaptation, but the underlying molecular mechanisms are not yet understood. Therefore, one aim of this study was to identify the phenotypical effects of high La levels as observed during resistance or high intensity endurance training on the proliferation and differentiation in a model of activated SCs, C2C12 cells. Furthermore, possible signalling targets for La, such as p38 mitogen-activated protein kinase (p38 MAPK), and subsequent histone modifications were investigated. Lastly, to confirm the observed mechanisms in vivo, a human intervention study was conducted. Treatment with La (10 mM, 20 mM) increased the serum deprivation-induced withdrawal from the cell cycle and initiated early differentiation in C2C12 cells as analysis of gene expression and protein patterns of cell cycle (Ki67, Trp53, and Cdkn1a) and differentiation markers (Pax7, Myf5, myogenin, and myosin heavy chain) revealed. However, La delays late differentiation in a dose-dependent manner. La-induced production of ROS, marked by high 8-epi-PGF2α levels, might at least be partly responsible as the effects induced by La were reversible by the addition of the antioxidants ascorbic acid, N-acetylcysteine, or linolenic acid. Observed downregulation of p38 MAPK activation and its downstream modifications histone 3 lysine 4 (H3K4) and histone 3 lysine 27 (H3K27) trimethylation suggests that La inhibits late differentiation progress by this mechanism which is crucial for muscle specific gene transcription. Experiments using the p38 specific inhibitor SB203580 add further evidence for this hypothesis. Additionally, it was demonstrated that diminished p38 MAPK activation and subsequent histone modifications are conserved in differentiated muscle tissue in vivo. Conclusively, the reported data confirm that La modifies skeletal muscle adaptation via a ROS-sensitive signalling network by delaying late differentiation of SCs, an important mechanism of skeletal muscle adaptation. This conclusion implies reassessment of traditional views on training design and periodisation in order to accelerate skeletal muscle adaptation

Food and macronutrient intake of elite Ethiopian distance runners

Background: Explanations for the phenomenal success of East African distance runners include unique dietary practices. The aim of the present study was to assess the food and macronutrient intake of elite Ethiopian distance runners during a period of high intensity exercise training at altitude and prior to major competition. Methods: The dietary intake of 10 highly-trained Ethiopian long distance runners, living and training at high altitude (approximately 2400 m above sea level) was assessed during a 7 day period of intense training prior to competition using the standard weighed intake method. Training was also assessed using an activity/training diary. Results: Body mass was stable (i.e., was well maintained) over the assessment period (pre: 56.7 +/- 4.3 kg vs. post: 56.6 +/- 4.2 kg, P = 0.54; mean +/- SD). The diet comprised of 13375 +/- 1378 kJ and was high in carbohydrate (64.3 +/- 2.6%, 545 +/- 49 g, 9.7 +/- 0.9 g/kg). Fat and protein intake was 23.3 +/- 2.1% (83 +/- 14 g) and 12.4 +/- 0.6% (99 +/- 13 g, 1.8 +/- 0.2 g/kg), respectively. Fluid intake comprised mainly of water (1751 +/- 583 mL), while no fluids were consumed before or during training with only modest amounts being consumed following training. Conclusions: Similar to previous studies in elite Kenyan distance runners, the diet of these elite Ethiopian distance runners met most recommendations of endurance athletes for macronutrient intake but not for fluid intake

Tenomodulin is Required for Tendon Endurance Running and Collagen I Fibril Adaptation to Mechanical Load

Tendons are dense connective tissues that attach muscles to bone with an indispensable role in locomotion because of their intrinsic properties of storing and releasing muscle-generated elastic energy. Tenomodulin (Tnmd) is a well-accepted gene marker for the mature tendon/ligament lineage and its loss-of -function in mice leads to a phenotype with distinct signs of premature aging on tissue and stem/progenitor cell levels. Based on these findings, we hypothesized that Tnmdmight be an important factor in the functional performance of tendons. Firstly, we revealed that Tnmd is amechanosensitive gene and that the C-terminus of the protein colocalizewith collagen I-type fibers in the extracellular matrix. Secondly, using an endurance training protocol, we compared Tnmd knockout mice with wild types and showed that Tnmd deficiency leads to significantly inferior running performance that further worsens with training. In these mice, endurance running was hindered due to abnormal response of collagen I cross-linking and proteoglycan genes leading to an inadequate collagen I fiber thickness and elasticity. In sum, our study demonstrates that Tnmd is required for proper tendon tissue adaptation to endurance running and aids in better understanding of the structural-functional relationships of tendon tissues. (C) 2017 The Authors. Published by Elsevier B.V

Metabolic regulation of C2C12 myoblasts by inhibiting the pro-myogenic effect of p38 activation

Willkomm L, Wördehoff A, Gehlert S, Suhr F, Bloch W. Metabolic regulation of C2C12 myoblasts by inhibiting the pro-myogenic effect of p38 activation. Presented at the 7th International Meeting of the Stem Cell Network NRW, Köln

Die Rolle der p38-MAPK bei der Laktat-induzierten Differenzierungsverzögerung von C2C12 Myoblasten

Wördehoff A, Willkomm L, Gehlert S, Suhr F, Bloch W. Die Rolle der p38-MAPK bei der Laktat-induzierten Differenzierungsverzögerung von C2C12 Myoblasten. Presented at the 44. Deutscher Sportärztekongress, Frankfurt am Main

p38 MAPK activation and H3K4 trimethylation is decreased by lactate in vitro and high intensity resistance training in human skeletal muscle.

Exercise induces adaptation of skeletal muscle by acutely modulating intracellular signaling, gene expression, protein turnover and myogenic activation of skeletal muscle stem cells (Satellite cells, SCs). Lactate (La)-induced metabolic stimulation alone has been shown to modify SC proliferation and differentiation. Although the mechanistic basis remains elusive, it was demonstrated that La affects signaling via p38 mitogen activated protein kinase (p38 MAPK) which might contribute to trimethylation of histone 3 lysine 4 (H3K4me3) known to regulate satellite cell proliferation and differentiation. We investigated the effects of La on p38 MAPK and H3K4me3 in a model of activated SCs. Differentiating C2C12 myoblasts were treated with La (20 mM) and samples analysed using qRT-PCR, immunofluorescence, and western blotting. We determined a reduction of p38 MAPK phosphorylation, decreased H3K4me3 and reduced expression of Myf5, myogenin, and myosin heavy chain (MHC) leading to decreased differentiation of La-treated C2C12 cells after 5 days of repeated La treatment. We further investigated whether this regulatory pathway would be affected in human skeletal muscle by the application of two different resistance exercise regimes (RE) associated with distinct metabolic demands and blood La accumulation. Muscle biopsies were obtained 15, 30 min, 1, 4, and 24 h post exercise after moderate intensity RE (STD) vs. high intensity RE (HIT). Consistent with in vitro results, reduced p38 phosphorylation and blunted H3K4me3 were also observed upon metabolically demanding HIT RE in human skeletal muscle. Our data provide evidence that La-accumulation acutely affects p38 MAPK signaling, gene expression and thereby cell differentiation and adaptation in vitro, and likely in vivo

Intense Resistance Exercise Promotes the Acute and Transient Nuclear Translocation of Small Ubiquitin-Related Modifier (SUMO)-1 in Human Myofibres

Protein sumoylation is a posttranslational modification triggered by cellular stress. Because general information concerning the role of small ubiquitin-related modifier (SUMO) proteins in adult skeletal muscle is sparse, we investigated whether SUMO-1 proteins will be subjected to time-dependent changes in their subcellular localization in sarcoplasmic and nuclear compartments of human type I and II skeletal muscle fibers in response to acute stimulation by resistance exercise (RE). Skeletal muscle biopsies were taken at baseline (PRE), 15, 30, 60, 240 min and 24 h post RE from 6 male subjects subjected to a single bout of one-legged knee extensions. SUMO-1 localization was determined via immunohistochemistry and confocal laser microscopy. At baseline SUMO-1 was localized in perinuclear regions of myonuclei. Within 15 and up to 60 min post exercise, nuclear SUMO-1 localization was significantly increased (p < 0.01), declining towards baseline levels within 240 min post exercise. Sarcoplasmic SUMO-1 localization was increased at 15 min post exercise in type I and up to 30 min post RE in type II myofibres. The changing localization of SUMO-1 proteins acutely after intense muscle contractions points to a role for SUMO proteins in the acute regulation of the skeletal muscle proteome after exercise

Intense resistance exercise induces early and transient increases in ryanodine receptor 1 phosphorylation in human skeletal muscle.

BACKGROUND: While ryanodine receptor 1 (RyR1) critically contributes to skeletal muscle contraction abilities by mediating Ca²⁺ion oscillation between sarcoplasmatic and myofibrillar compartments, AMP-activated protein kinase (AMPK) senses contraction-induced energetic stress by phosphorylation at Thr¹⁷². Phosphorylation of RyR1 at serine²⁸⁴³ (pRyR1Ser²⁸⁴³) results in leaky RyR1 channels and impaired Ca²⁺homeostasis. Because acute resistance exercise exerts decreased contraction performance in skeletal muscle, preceded by high rates of Ca²⁺-oscillation and energetic stress, intense myofiber contractions may induce increased RyR1 and AMPK phosphorylation. However, no data are available regarding the time-course and magnitude of early RyR1 and AMPK phosphorylation in human myofibers in response to acute resistance exercise. PURPOSE: Determine the effects and early time-course of resistance exercise on pRyR1Ser²⁸⁴³ and pAMPKThr¹⁷² in type I and II myofibers. METHODS: 7 male subjects (age 23±2 years, height: 185±7 cm, weight: 82±5 kg) performed 3 sets of 8 repetitions of maximum eccentric knee extensions. Muscle biopsies were taken at rest, 15, 30 and 60 min post exercise. pRyR1Ser²⁸⁴³ and pAMPKThr¹⁷² levels were determined by western blot and semi-quantitative immunohistochemistry techniques. RESULTS: While total RyR1 and total AMPK levels remained unchanged, RyR1 was significantly more abundant in type II than type I myofibers. pRyR1Ser²⁸⁴³ increased 15 min and peaked 30 min (p<0.01) post exercise in both myofiber types. Type I fibers showed relatively higher increases in pRyR1Ser²⁸⁴³ levels than type II myofibers and remained elevated up to 60 min post resistance exercise (p<0.05). pAMPKThr¹⁷² also increased 15 to 30 min post exercise (p<0.01) in type I and II myofibers and in whole skeletal muscle. CONCLUSION: Resistance exercise induces acutely increased pRyR1Ser²⁸⁴³ and concomitantly pAMPKThr¹⁷² levels for up to 30 min in resistance exercised myofibers. This provides a time-course by which pRyR1Ser²⁸⁴³ can mechanistically impact Ca²⁺handling properties and consequently induce reduced myofiber contractility beyond immediate fatiguing mechanisms

Blood lactate levels in subjects of STD and HIT RE groups before and in the early time course after a single session of resistance exercise.

<p>Blood lactate levels in subjects of STD and HIT RE groups before and in the early time course after a single session of resistance exercise.</p