Explore the vast range of titles available.

Background Protein supplementation improves physiological adaptations to endurance training, but the impact on adaptive changes in the skeletal muscle transcriptome remains elusive. The present analysis was executed to determine the impact of protein supplementation on changes in the skeletal muscle transcriptome following 5-weeks of endurance training. Results Skeletal muscle tissue samples from the vastus lateralis were taken before and after 5-weeks of endurance training to assess changes in the skeletal muscle transcriptome. One hundred and 63 genes were differentially expressed after 5-weeks of endurance training in both groups ( q-value< 0.05). In addition, the number of genes differentially expressed was higher in the protein group (PRO) (892, q-value< 0.05) when compared with the control group (CON) (440, q-value< 0.05), with no time-by-treatment interaction effect (q-value> 0.05). Endurance training primarily affected expression levels of genes related to extracellular matrix and these changes tended to be greater in PRO than in CON. Conclusions Protein supplementation subtly impacts endurance training-induced changes in the skeletal muscle transcriptome. In addition, our transcriptomic analysis revealed that the extracellular matrix may be an important factor for skeletal muscle adaptation in response to endurance training. This trial was registered at clinicaltrials.gov as NCT03462381, March 12, 2018. Trial registration This trial was registered at clinicaltrials.gov as NCT03462381 .

Aims Heart failure with reduced ejection fraction (HFrEF) induces skeletal muscle mitochondrial abnormalities that contribute to exercise limitation; however, specific mitochondrial therapeutic targets remain poorly established. This study quantified the relationship and contribution of distinct mitochondrial respiratory states to prognostic whole‐body measures of exercise limitation in HFrEF. Methods and results Male patients with HFrEF (n = 22) were prospectively enrolled and underwent ramp‐incremental cycle ergometry cardiopulmonary exercise testing to determine exercise variables including peak pulmonary oxygen uptake (V̇O2peak), lactate threshold (V̇O2LT), the ventilatory equivalent for carbon dioxide (V̇E/V̇CO2LT), peak circulatory power (CircPpeak), and peak oxygen pulse. Pectoralis major was biopsied for assessment of in situ mitochondrial respiration. All mitochondrial states including complexes I, II, and IV and electron transport system (ETS) capacity correlated with V̇O2peak (r = 0.40–0.64; P < 0.05), V̇O2LT (r = 0.52–0.72; P < 0.05), and CircPpeak (r = 0.42–0.60; P < 0.05). Multiple regression analysis revealed that combining age, haemoglobin, and left ventricular ejection fraction with ETS capacity could explain 52% of the variability in V̇O2peak and 80% of the variability in V̇O2LT, respectively, with ETS capacity (P = 0.04) and complex I (P = 0.01) the only significant contributors in the model. Conclusions Mitochondrial respiratory states from skeletal muscle biopsies of patients with HFrEF were independently correlated to established non‐invasive prognostic cycle ergometry cardiopulmonary exercise testing indices including V̇O2peak, V̇O2LT, and CircPpeak. When combined with baseline patient characteristics, over 50% of the variability in V̇O2peak could be explained by the mitochondrial ETS capacity. These data provide optimized mitochondrial targets that may attenuate exercise limitations in HFrEF.

It is well established that glycogen depletion affects endurance exercise performance negatively. Moreover, numerous studies have demonstrated that post-exercise carbohydrate ingestion improves exercise recovery by increasing glycogen resynthesis. However, recent research into the effects of glycogen availability sheds new light on the role of the widely accepted energy source for adenosine triphosphate (ATP) resynthesis during endurance exercise. Indeed, several studies showed that endurance training with low glycogen availability leads to similar and sometimes even better adaptations and performance compared to performing endurance training sessions with replenished glycogen stores. In the case of resistance exercise, a few studies have been performed on the role of glycogen availability on the early post-exercise anabolic response. However, the effects of low glycogen availability on phenotypic adaptations and performance following prolonged resistance exercise remains unclear to date. This review summarizes the current knowledge about the effects of glycogen availability on skeletal muscle adaptations for both endurance and resistance exercise. Furthermore, it describes the role of glycogen availability when both exercise modes are performed concurrently.

Background and objectives: Myokines are proteins produced and released by skeletal muscle in response to exercise, and suggested to play a role in exercise-induced adaptations of muscle tissue. Nutrient availability, in particular carbohydrate (CHO), is proposed as a potential regulator of myokine responses. We evaluated the effects of a pre-exercise carbohydrate-rich meal versus a low carbohydrate -high fat- meal on plasma myokine responses to resistance exercise after a glycogen-depleting endurance exercise earlier that day. Methods: Fifteen males performed two experimental days with a 90 min bout of endurance exercise at 70% VO2max in the morning (8.30-10 am) and resistance exercise in the afternoon (2- 2.30 pm):5 x 8 80% 1-RM repetitions of bilateral leg press and extension. Either a high CHO/low fat meal (110g CHO, 52g protein, 9g fat; ~750 kcal) or a iso-caloric low-CHO /high fat meal (20 gr CHO, 52g protein, 51g fat) was provided 2h before resistance exercise (noon). Blood was drawn after an overnight fast and at regular time intervals up to 3 hours after resistance exercise to measure plasma myokine/cytokine levels. Results: Postprandial plasma glucose and insulin levels were higher, and FFA lower, on the high-CHO condition compared to the low-CHO. IL-6 increased post-exercise, and was significantly higher after the low-CHO meal in the post-resistance exercise period compared to the high-CHO meal. IL-8 and IL-10 were only increased after the endurance exercise. IL-15 increased postprandial on the high-CHO condition only, and was increased in the early post-resistance exercise period, with a slightly higher level on the high-CHO condition. TNFα and Decorin did not show a clear response, while ANGPTL4 was slightly elevated post-exercise, and strongly increased in the postprandial period, with no differences between meals. MCP-1 tended, on both occasions, to increase after the endurance exercise with subsequent a reduction below baseline. Conclusions: The composition of the pre-exercise meal did in general not influence myokine responses in the post-resistance exercise period, although plasma IL-6 levels were higher in the low- CHO condition compared with high-CHO. Our findings support the view that pre-resistance exercise carbohydrate availability does not have a major impact on acute responses of myokines.

Skeletal muscle responds to exercise by a diversity of processes that collectively contribute to short-term and structural adaptations to the demanded performance capacities. There is common consensus that, in general, adequate nutrient availability during and after exercise is important to maximise skeletal muscle adaptation and ultimately performance. At the same time, several knowledge gaps remain regarding the precise mechanisms underlying these effects on adaptation, the most optimal nutrient composition in relation to type of exercise, optimal timing etc.This dissertation addresses some of these unsolved issues by studying the role of carbohydrates and proteins during adaptation following different forms of exercise. The first part (chapters 2–4) focusses on carbohydrate availability with resistance exercise, whereas the second part (chapters 5–7) specifically addresses the effects and potential of protein supplementation with endurance training. In chapter 2 we reviewed the existing literature regarding the role of skeletal muscle glycogen with endurance and resistance exercise. Based on this review we concluded that the role of muscle glycogen levels and/or carbohydrate availability on the skeletal muscle adaptive response to resistance exercise requires further scientific attention. To experimentally explore this, we assessed the impact of a pre-exercise meal that differed in macronutrient content on skeletal muscle glycogen levels and acute transcriptional level analysing specific mRNAs in the post-resistance exercise period in chapter 3. Specifically, after a glycogen depleting endurance exercise session in the morning, subjects received an isocaloric mixed meal containing different amounts of carbohydrates and fat 2 hours before a resistance exercise session in the afternoon, while ample protein was provided throughout the day. We hypothesized that some of the selected mRNAs associated with substrate metabolism and mitochondrial biogenesis would differ between the nutritional conditions, without any changes in proteolytic genes. The findings described in chapter 3 demonstrated that muscle mRNA responses related to exercise adaptation were minimally affected by the preexercise meals that differed in macronutrient composition. In chapter 4, derived from the same study, we describe the analysis of a number of plasma cytokine patterns during the day to investigate whether these mediators were affected by carbohydrate availability. We hypothesized that some selected cytokines would differ between nutritional conditions, whereas other circulating cytokines suggested to be involved in skeletal muscle adaptation would not respond differently. Our main finding was that a pre-exercise meal in general did not influence plasma cytokine responses in the post-resistance exercise period. Findings of chapter 3 and 4 contribute to the view that carbohydrate availability during resistance exercise is of minor importance when aiming for an acute positive skeletal muscle adaptive response. In addition, our data question the importance of carbohydrates as both substrate for resistance exercise and as modulator of the skeletal muscle response that underlies adaptation. Yet, at present it might be premature to change carbohydrate recommendations for individuals performing resistance exercise. Shifting our focus to proteins, we first reviewed the effects and possible underlying physiological mechanisms of protein supplementation on the adaptive response to endurance training in Chapter 5. To further explore these insights, we performed a double-blind randomised controlled trial with repeated measures to determine whether protein supplementation impacts the adaptive response to endurance training. In chapter 6 we provide proof-ofconcept that protein supplementation elicited greater increases in VO2max and stimulated lean mass gain in response to prolonged endurance training. To our knowledge, this was the first double-blind randomised controlled trial with repeated measures showing that protein supplementation enhances the adaptive response to endurance training. These remarkable effects of protein on VO2max that were observed give rise to questions regarding their underlying mechanisms. To this end, we analysed the muscle transcriptome to gain insight into changes in the steady-state gene expression. In chapter 7, we demonstrated that prolonged endurance training changed expression of genes involved in extracellular matrix organisation, energy metabolism and oxidative phosphorylation. Changes in extracellular matrix organisation tended to be greater in the protein group than in the control group and these greater transcriptional changes may reflect the enhanced physiological adaptation as a result of protein supplementation.

Carbohydrate availability is proposed as a potential regulator of cytokine responses. We aimed to evaluate the effect of a preresistance exercise carbohydrate meal versus fat meal on plasma cytokine responses to resistance exercise after an endurance exercise earlier that day. Thirteen young, healthy, recreationally active males performed two experimental days with endurance exercise in the morning and resistance exercise in the afternoon. Either a carbohydrate (110 g carbohydrate, 52 g protein, 9 g fat; ~750 kcal) or an isocaloric fat meal (20 gr carbohydrate, 52 g protein, 51 g fat) was provided 2 h before resistance exercise. Blood was taken at baseline and at regular time intervals to measure circulating plasma cytokine levels (e.g. IL‐6, IL‐8, IL‐10, IL‐15, TNFα, ANGPTL4, decorin and MCP‐1). Plasma glucose and insulin were higher in the postprandial period before the start of the resistance exercise on the carbohydrate condition, while free fatty acids were reduced. At 2 h postresistance exercise, IL‐6 concentrations were higher in the fat condition compared to the carbohydrate condition (P < 0.05). In addition, in both conditions IL‐6 levels were higher at all time points compared with baseline (P < 0.05). The pattern of increase in plasma IL‐8 and IL‐10 did not differ significantly between conditions (P > 0.05). There were no differences between conditions on TNFα levels and levels remain constant when compared with baseline (P > 0.05). ANGPTL4, IL‐15, Decorin and MCP‐1 showed no differences between the fat and carbohydrate condition (P > 0.05). The composition of the pre‐exercise meal did in general not influence cytokine responses in the postresistance exercise period, except postresistance exercise circulating plasma IL‐6 levels being higher in the fat condition compared with carbohydrate. Our findings support the view that pre‐exercise carbohydrate availability does not have a major impact on acute responses of circulating plasma cytokines in humans. In this study, we investigated whether pre‐exercise nutrient availability such as carbohydrates and fat influenced circulating cytokines concentrations with resistance exercise on a concurrent exercise day.