Improve Endurance Performance Research Articles

Acute dose-response effect of photobiomodulation therapy on 5-km running performance in trained runners: a randomized, double-blind, placebo-controlled, crossover study.

Photobiomodulation therapy (PBMT) has been advocated as a potential intervention to improve muscle performance and recovery in the health and sports context. However, the short- and long-term effects of PBMT on endurance running performance remain under-researched and controversial. The purpose of this study was to investigate the acute dose-response effect of PBMT with light-emitting diodes (LEDs) on endurance performance and rating of perceived exertion (RPE; 6-20 Borg) during a 5-km running trial in recreational runners. In a crossover design, eighteen young adult runners (28.7 ± 7.8 years) were randomized to receive 1 of 4 PBMT conditions (placebo, 300, 900, and 1260 Joules [J]) 60min before the 5-km running trial on four occasions, separated by a 2-wk washout period. The treatments were applied to the quadriceps, hamstrings, and gastrocnemius muscles of both legs using a device containing 200 LEDs (100 red and 100 infrared). The following variables were assessed: endurance performance (i.e. total time, mean velocity, and velocity in the split distances at the initial 200m and every 400m lap) and RPE in the split distances at the initial 200m and every 400m lap. Data normality and homogeneity were tested using Shapiro-Wilk's and Levene's tests, respectively. Differences between treatment conditions were assessed using the analysis of variance tests (one- or two-way ANOVA, depending on the comparisons), complemented by the Bonferroni post hoc test. There were significant time effects for the running velocity and RPE in the split distances (p < 0.0001), with no significant treatment-by-time interaction (running velocity, p = 0.59; RPE, p = 0.95). The mean velocity (p = 0.997), total time (p = 0.998), and total mean of the RPE (p = 0.91) were similar between treatment conditions. In conclusion, acute PBMT with LEDs at doses of 300, 900, and 1260J is not recommended for improving endurance performance and RPE in the 5-km running trial in recreational runners.

Effect of Heat Acclimatization, Heat Acclimation, and Intermittent Heat Training on Maximal Oxygen Uptake.

Maximal oxygen uptake (VO2max) is an important determinant of endurance performance. Heat acclimation/acclimatization (HA/HAz) elicits improvements in endurance performance. Upon heat exposure reduction, intermittent heat training (IHT) may alleviate HA/HAz adaptation decay; however, corresponding VO2max responses are unknown. VO2max is maintained after HAz/HA; IHT mitigates decrements in aerobic power after HAz/HA. Interventional study. Level 3. A total of 27 male endurance runners (mean ± SD; age, 36 ± 12 years; body mass, 73.03 ± 8.97 kg; height, 178.81 ± 6.39 cm) completed VO2max testing at 5 timepoints; baseline, post-HAz, post-HA, and weeks 4 and 8 of IHT (IHT4, IHT8). After baseline testing, participants completed HAz, preceded by 5 days of HA involving exercise to induce hyperthermia for 60 minutes in the heat (ambient temperature, 39.13 ± 1.37°C; relative humidity, 51.08 ± 8.42%). Participants were assigned randomly to 1 of 3 IHT groups: once-weekly, twice-weekly, or no IHT. Differences in VO2max, velocity at VO2max (vVO2), and maximal heart rate (HRmax) at all 5 timepoints were analyzed using repeated-measure analyses of variance with Bonferroni corrections post hoc. No significant VO2max or vVO2 differences were observed between baseline, post-HAz, or post-HA (P = 0.36 and P = 0.09, respectively). No significant group or time effects were identified for VO2max or vVO2 at post-HA, IHT4, and IHT8 (P = 0.67 and P = 0.21, respectively). Significant HRmax differences were observed between baseline and post-HA tests (P < 0.01). No significant group or time HRmax differences shown for post-HA, IHT4, and IHT8 (P = 0.59). VO2max was not reduced among endurance runners after HA/HAz and IHT potentially due to participants' similar aerobic training status and high aerobic fitness levels. HAz/HA and IHT maintain aerobic power in endurance runners, with HAz/HA procuring reductions in HRmax.

Effects of Limosilactobacillus reuteri ID-D01 Probiotic Supplementation on Exercise Performance and Gut Microbiota in Sprague-Dawley Rats.

The gut microbiota composition in animals and humans has recently been found to be influenced by exercise. Although Limosilactobacillus reuteri strains have notable probiotic properties that promote human health, understanding of its effects in combination with exercise and physical activity is limited. Therefore, this study examined the effects of L. reuteri ID-D01, a human-derived probiotic, on exercise performance and fatigue in Sprague-Dawley rats. Organ weight, maximal running distance, serum biochemistry, muscle performance, microbial community composition, and short-chain fatty acid (SCFA) levels were assessed. Results indicated that ID-D01 supplementation significantly improved endurance performance. Rats in the probiotic group demonstrated a significant increase in maximal running distance compared with that in the control group (p < 0.05). Additionally, levels of fatigue markers, such as lactate and creatine phosphokinase, were significantly reduced in the ID-D01-administered groups, suggesting its potential to alleviate exercise-induced fatigue. Microbiome analysis revealed a distinct shift in gut microbiota composition in response to ID-D01 administration. The group that received ID-D01 probiotics exhibited a significant increase in the abundance of SCFA-producing bacteria, particularly Akkermansia spp., compared with that in the control groups. Furthermore, they showed elevated production of SCFAs, such as acetate and butyrate. In conclusion, this study demonstrated that ID-D01 can enhance exercise performance and reduce fatigue. Herein, we highlighted that human-derived probiotics could improve physical performance, as observed by changes in gut microbiota composition and SCFA production.

Practical Application of Respiratory Muscle Training in Endurance Sports

ABSTRACT Since traditional sport-specific training or exercise programs do not create enough stimulus to improve the function of the respiratory muscles, the rationale to introduce respiratory muscle training (RMT) emerged. RMT is associated with improved endurance performance and pulmonary function, and it reduced respiratory fatigue, perceived exertion, or breathlessness. The purpose of this article is to provide coaches with tools to select the appropriate form of RMT in the context of the athletes' needs, using appropriate methods, techniques, devices, and testing protocols. The video abstract is presented in Supplemental Digital Content as SDC 1.

The effect of aerobic running on children's thinking and endurance

The aim is to assess the impact of prolonged running on the endurance and thinking indicators of children aged 9-10 years in physical education classes at school. Methods – the pedagogical experiment was conducted for 4 months on the basis of the secondary general educational school 60 (Kirov, Russia), 120 schoolchildren from the third grades took part in it. 34 physical education lessons were held in each class. Schoolchildren from the control group were engaged in a standard physical education program for younger schoolchildren. The children from the experimental group also worked within the framework of the usual program, but during each lesson they performed a long run of 6 minutes. Overall endurance was assessed using the K Cooper (6 minutes) test, the students' thinking was evaluated by the "Simple Analogies" test. Both tests were performed before and after the pedagogical experiment. Results – before the start of the study, there were no significant differences between classes in both tests (p&gt;0.05). After the end of the study, the performance of children in the control group improved in the endurance test by 6.8% and 7.2% (p&gt;0.05), and in the experimental group improved by 24.9% and 18.9% (p&lt;0.05). In the thinking test, the indicators of the control group increased by 7.3% and 8.4% (p&gt;0.05), and in the experimental group by 24.8% and 23.5% (p&lt;0.05). Conclusion – long running can be introduced into the physical education program at school to improve endurance performance and thinking of schoolchildren 9-10 years old. Keywords: Health, Physical culture, Aerobic abilities, Physical qualities, Psychodiagnostics, School curriculum.

The Prolyl Hydroxylase Domain 2 (PHD2) Deficiency Enhances Maximal Exercise Capacity

PURPOSE: Hypoxic training is beneficial for improving endurance performance. Hypoxia-inducible factor (HIF) is a key transcription factor that regulates the hypoxic-responsive pathway. Stabilization of HIF by inactivating prolyl hydroxylase domain protein 2 (PHD2) under low oxygen tension, triggers angiogenesis, erythropoiesis, and glycolysis. Glycolytic capacity is essential to perform anaerobic exercise. This study aims to verify whether the upregulation of glycolytic metabolism under the hypoxic-responsive pathway enhances exercise capacity.METHODS: We employed tamoxifen-inducible conditional PHD2 knock-out (KO) mice that exhibited stabilized HIF-alpha. To evaluate anaerobic exercise capacity, a rodent treadmill exercise test was performed. RNA sequencing (RNA-seq) analysis was conducted using C2C12 myoblasts after PHD2 siRNA transfection.RESULTS: PHD2KO mice exhibited increased red blood cell counts, hemoglobin, and hematocrit values, along with enhanced maximal exercise performance compared to littermate wild-type (WT) mice. PHD2 deficiency promoted maximal exercise capacity and resulted in lower blood lactate levels. RNAseq analysis revealed that PHD2-deficient myoblasts increased the expression of genes related to glycolysis, gluconeogenesis, and muscle contraction.CONCLUSIONS: These findings suggest that PHD2 deficiency-induced activation of the hypoxic-responsive pathway enhances maximal exercise capacity.

High-intensity interval training programs and their impact on endurance performance in handball players: A systematic review

Abstract Study aim: This systematic review aimed to identify and analyze the available evidence about the effects of high-intensity interval training (HIIT) interventions on endurance performance in handball players. Material and methods: The search for relevant literature was conducted across prominent databases, including PubMed, Scopus, SPORTDiscus, and Web of Science Core Collection. The eligibility criteria focused on healthy handball players, without restrictions on age, sex, or competitive level, who were exposed to HIIT interventions, either alone or in combination with other training methods. The methodological assessment employed the RoB2 and ROBINS scales. A screening process was executed, evaluating 434 titles, leading to the inclusion of 17 eligible studies in this systematic review, comprising a total of 369 participants. Results: Most studies on HIIT in handball involved tier-two athletes (trained/developmental) and mostly men. The training frequency typically implemented was twice per week, with a duration between 4 and 12 weeks, with different types of HIIT. There was considerable variation in outcomes across the included studies, with most of them demonstrating a significant positive impact of HIIT on improving endurance performance when compared to controls. Conclusion: In conclusion, the predominant focus of the overall analyzed studies was on the effects of different HIIT interventions in obtaining positive performance adaptations assessed by field-based tests in handball players.

Young Females’ Longitudinal Relationship of Endurance Performance - A Partial Regression Analysis

Coaches and practitioners strive to use methods based on outcome measurements that are evidence-based to maximize female athlete performance, but due to a lack female representation in exercise science research, this is often problematic. The primary goal was to investigate the correlation between maximal oxygen uptake, blood lactate, and running economy in young females. Secondarily, the objective was to observe the longitudinal association between alterations in maximal oxygen uptake, blood lactate, and running economy responses to six weeks of endurance training. Young female athletes (n = 18) were randomized into a weighted vest (n = 10) or non-weighted vest (n = 8) group. Two separate graded treadmill tests for maximal oxygen uptake, blood lactate, and running economy were performed at baseline and post-six weeks of endurance training, which occurred at a frequency of three times per week for six weeks. A slight positive relationship between baseline- maximal oxygen uptake and running economy, r = 0.33, and a moderate positive relationship between baseline- blood lactate and running economy, r = 0.46, were observed. After controlling body composition, a strong positive relationship between post- maximal oxygen uptake and running economy, r = 0.59, and a strong positive relationship between post- blood lactate and running economy, r = 0.85, were observed. This study shows baseline assessments of previously mentioned performance traits may not be related. A weighted vest is considered a safe and alternative ergogenic aid that can be incorporated into an endurance training program. A six-week endurance training program is sufficient time to induce cardiovascular adaptations and improve endurance performance.

Effects of HMB on Endurance Performance in a Healthy Population: A Systematic Review and Meta-Analysis.

Fernández-Landa, J, Todorovic, N, Santibañez-Gutierrez, A, Ostojic, SM, Calleja-González, J, Sekulic, D, and Mielgo-Ayuso, J. Effects of HMB on endurance performance in a healthy population: a systematic review and meta-analysis. J Strength Cond Res 38(4): e202-e210, 2024-β-hydroxy-β-methylbutyrate (HMB) has been used extensively as a dietary supplement for athletes and physically active people. However, the ergogenic effect of HMB supplementation on endurance performance is still unclear. Therefore, this systematic review and meta-analysis (SRMA) aimed to assess HMB supplementation on endurance performance and V̇O 2 max . This SRMA followed PRISMA guidelines. Three electronic databases were searched (PubMed/Medline, Web of Science [WOS], and Scopus) from inception until April 3, 2023. In this SRMA, human experimental trials, controlled with a placebo group, assessing the effect of HMB supplementation on endurance performance in a healthy population were included. The quality of the studies was assessed by the Physiotherapy Evidence Database (PEDro) scale. The study protocol was registered in the Prospective Register of Systematic Review (PROSPERO): CRD42022341790. Eleven studies involving 279 participants met the inclusion criteria. The results displayed a significant improvement on endurance performance (pooled standardized mean difference [SMD] = 0.58 [0.28-0.87]) and V̇O 2 max (pooled SMD = 0.58 [0.21-0.95]) after HMB ingestion. Moreover, after the exclusion of the studies not evenly distributed around the base of the funnel plot, the results continued to be significantly positive in endurance performance (pooled SMD = 0.38 [0.22-0.53]) and V̇O 2 max (pooled SMD = 0.25 [0.09-0.42]). In conclusion, HMB (3 g·d -1 ) ingestion during 2-12 weeks significantly improves endurance performance and V̇O 2 max .

Motor-Respiratory Coupling Improves Endurance Performance during Rhythmic Isometric Handgrip Exercise.

This study aimed to evaluate whether motor-respiratory coupling exists in rhythmic isometric handgrip exercises and its effect on endurance performance. In addition, the mechanism underlying observed effects was to be investigated if higher motor-respiratory coupling rate could enhance endurance performance. Eleven subjects completed three rhythmic isometric handgrip trials to task failure in a randomized manner. After one pretraining session to determine personal grip frequency, one trial was performed without respiration requirement (CON), and two trials were performed with inspiration-motor coupling (IMC) or expiration-motor coupling. Changes in maximal voluntary contraction (MVC) and EMG were used to measure neuromuscular fatigue. Force data during test were used to assess exercise intensity. Another 10 subjects completed electrical stimulation-induced finger flexion and extension during normal inspiration, normal expiration, fast inspiration, fast expiration, and breath holding. Force changes of different breathing conditions were compared. Normalized exercise time to exhaustion was significantly longer in IMC (1.27 ± 0.23) compared with expiration-motor coupling (0.82 ± 0.18) and CON (0.91 ± 0.18, P < 0.001). ΔMVC, grip frequency, force, and EMG indices were not different among conditions (all P > 0.05). Electrical stimulation-induced finger extensor force was significant higher during fast inspiration (1.11 ± 0.09) than normal respiration (1.00 ± 0.05) and fast expiration (0.94 ± 0.08, P < 0.05). IMC is an effective way to improve endurance performance of rhythmic handgrip exercise. This is likely due to a reduction in the energy consumption of motion control, as evidenced by similar peripheral fatigue in different conditions and modulation of corticospinal excitability by respiration.

What if gastrointestinal complications in endurance athletes were gut injuries in response to a high consumption of ultra-processed foods? Please take care of your bugs if you want to improve endurance performance: a narrative review.

To improve performance and recovery faster, athletes are advised to eat more often than usual and consume higher doses of simple carbohydrates, during and after exercise. Sports energetic supplements contain food additives, such as artificial sweeteners, emulsifiers, acidity regulators, preservatives, and salts, which could be harmful to the gut microbiota and impair the intestinal barrier function. The intestinal barrier plays a critical function in bidirectionally regulation of the selective transfer of nutrients, water, and electrolytes, while preventing at the same time, the entrance of harmful substances (selective permeability). The gut microbiota helps to the host to regulate intestinal homeostasis through metabolic, protective, and immune functions. Globally, the gut health is essential to maintain systemic homeostasis in athletes, and to ensure proper digestion, metabolization, and substrate absorption. Gastrointestinal complaints are an important cause of underperformance and dropout during endurance events. These complications are directly related to the loss of gut equilibrium, mainly linked to microbiota dysbiosis and leaky gut. In summary, athletes must be cautious with the elevated intake of ultra-processed foods and specifically those contained on sports nutrition supplements. This review points out the specific nutritional interventions that should be implemented and/or discontinued depending on individual gut functionality.

Running with whole-body electromyostimulation improves physiological determinants of endurance performance – a randomized control trial

BackgroundThis study aimed to evaluate the physiological and metabolic adaptations to an eight-week running intervention with whole-body electromyostimulation (wbEMS) compared to running without wbEMS.MethodsIn a randomized controlled trial (RCT), 59 healthy participants (32 female/ 27 male, 41 ± 7 years, rel.V̇O2max 40.2 ± 7.4 ml/min/kg) ran twice weekly à 20 min for eight weeks either with a wbEMS suit (EG) or without wbEMS (control group, CG). Before and after the intervention, (i) rel.V̇O2max, heart rate and time to exhaustion were recorded with an incremental step test with an incremental rate of 1.20 km/h every 3 min. They were interpreted at aerobic and (indirect) anaerobic lactate thresholds as well as at maximum performance. (ii) Resting metabolic rate (RQ) as well as (iii) body composition (%fat) were assessed.ResultsFollowing the intervention, V̇O2max was significantly enhanced for both groups (EG ∆13 ± 3%, CG ∆9 ± 3%). Velocity was elevated at lactate thresholds and maximum running speed (EG ∆3 ± 1%, CG ∆2 ± 1%); HRmax was slightly reduced by -1 beat/min. No significant changes were observed for time until exhaustion and lactate. RQ was significantly enhanced following both trainings by + 7%. %fat was reduced for both groups (EG ∆-11 ± 3%, CG ∆-16 ± 5%), without any changes in body mass. Results did not differ significantly between groups.ConclusionsBoth interventions had a positive impact on aerobic power. The rightward shift of the time-velocity graph points towards improved endurance performance. The effects of wbEMS are comparable to those after high-intensity training and might offer a time-efficient alternative to affect physiological and metabolic effects.Trial registrationGerman Clinical Trials Register, ID DRKS00026827, date 10/26/21.

Effect of sprint interval training load on maximal oxygen uptake in trained men.

Sprint interval training (SIT) improves maximal aerobic and anaerobic performance, including oxygen uptake (VO2<inf>max</inf>), power output, and sprint performance. This study aimed to investigate the effect of SIT load on V̇O<inf>2max</inf> in trained subjects. SIT was performed twice a week for three weeks by twenty-four trained men (aged: 20.7±2.7, V̇O<inf>2max</inf> 43.6±6.5) and consisted of seven bouts of 10-s cycling sprints followed by a 4-min rest. Subjects were divided into two groups depending on the relative resistance of the load compared to their body mass (BM): 7.5% (S7.5) and 10% (S10). We measured the peak power, mean power, and peak cadence in SIT during the first and final sessions. V̇O<inf>2max</inf>, maximum aerobic power (MAP), heart rate, and lactate (La) concentration were measured before and after SIT using incremental tests. After 3 weeks of SIT, V̇O<inf>2max</inf>, MAP, and La improved significantly in both S7.5 and S10 groups. In addition, changes in V̇O<inf>2max</inf> in S10 were higher than those in S7.5 (2.2±11.2% vs. 9.23±9.57%, P=0.029, adjusted by pre V̇O<inf>2max</inf>). MAP measurements showed the same results (2.2±11.3% vs. 8.3±10.0%, P=0.015, adjusted by pre-MAP). However, there was no significant interaction between time and group. A significant increase in peak cadence from first session to sixth sessions was observed in S7.5 (P=0.01, ES = 0.93, 95% confidence interval [CI]: 0.02-1.78) but not in S10 (P=0.132, ES = 0.22, 95% [CI]: -0.59-1.01). Our results suggest that 3 weeks of SIT improves endurance performance in trained subjects. It seems that SIT at 10% load may tend to be more effective.

A 0.1% L-Menthol Mouth Swill in Elite Male Rugby Players Has Different Effects in Forwards and Backs.

Menthol mouth swills can improve endurance performance in the heat, which is attributed to attenuations in nonthermally derived thermal sensation (TS) and perception of effort. However, research in elite team-sport athletes is absent. Therefore, this study investigated the performance and TS responses to a 0.1% menthol mouth rinse (MR) or placebo (PLA) among elite male rugby union players. Twenty-seven (15 Forwards and 12 Backs) elite male Super Rugby players completed two 3-minute 15-a-side rugby-specific conditioning blocks, with MR or PLA provided at the start of training (baseline), at the start of each 3-minute block (swill 1 [S1] and swill 2 [S2]), and at the end of training (swill 3 [S3]). TS was assessed using the American Society of Heating, Refrigerating and Air-Conditioning Engineers 9-point Analog Sensation Scale after each swill and at baseline (preconditioning block). Acceptability was measured after baseline swill and S3 using a 5-question Likert scale. Physical performance was measured throughout training using global positioning system metrics. MR attenuated TS from baseline to S1 (P = .003, SD = 1.01) and S2 (P = .002, SD = 1.09) in Forwards only, compared with PLA. Acceptability was higher only for Forwards in MR versus PLA at baseline (P = .003, SD = 1.3) and S3 (P = .004, SD = 0.75). MR had no effect on physical performance metrics (P > .05). MR attenuated the rise in TS with higher acceptability at S1 and S3 (in Forwards only) with no effect on selected physical performance metrics. Longer-duration exercise (eg,a match) in hot-humid conditions eliciting markedly increased body temperatures could theoretically allow favorable changes in TS to enhance performance-these postulations warrant experimental investigation.

Self-regulatory processes in goal striving during excellent distance-running performances: A qualitative study

ObjectiveGoal setting can improve endurance performance, yet how endurance performers maintain goal striving and bring it to a successful close has received limited attention. In this study, we investigated the self-regulatory processes employed by long-distance runners during goal striving in excellent competitive performances. MethodThrough in-depth, event-focused interviews, we explored 21 long-distance runners’ experiences of goal striving in excellent competitive performances (M = 77.43 h post-race). Furthermore, we recruited 10 additional participants with relevant experiences (runner n = 7, coach n = 2; sport psychologist n = 1) for external member-reflection interviews. FindingsThrough our matrix analysis, we interpreted that by contrasting their current and future goal status periodically throughout their excellent performances, using a process called mental contrasting with implementation intentions (MCII), this helped the runners to make decisions about whether to persist with a goal, or disengage from a goal and reengage with an alternative. Furthermore, our findings depict how these goal decisions unfolded when runners perceived they were behind, equalling, or exceeding their goal(s). We also illustrate how goal revision was used as an adaptive process to maximise performance, and to avert or manage action crises. ConclusionsOur findings extend theoretical understandings of goal striving and the self-regulatory processes endurance performers employ to attain and/or adapt their goals. Psychological support provided for athletes should go beyond simply setting goals, but also include training on mental frameworks such as MCII to manage goal-striving challenges and decisional conflict encountered during performances.

Resistance training diminishes mitochondrial adaptations to subsequent endurance training in healthy untrained men.

We investigated the effects of performing a period of resistance training (RT) on the performance and molecular adaptations to a subsequent period of endurance training (ET). Twenty-five young adults were divided into an RT+ET group (n=13), which underwent 7weeks of RT followed by 7weeks of ET, and an ET-only group (n=12), which performed 7weeks of ET. Body composition, endurance performance and muscle biopsies were collected before RT (T1, baseline for RT+ET), before ET (T2, after RT for RT+ET and baseline for ET) and after ET (T3). Immunohistochemistry was performed to determine fibre cross-sectional area (fCSA), myonuclear content, myonuclear domain size, satellite cell number and mitochondrial content. Western blots were used to quantify markers of mitochondrial remodelling. Citrate synthase activity and markers of ribosome content were also investigated. RT improved body composition and strength, increased vastus lateralis thickness, mixed and type II fCSA, myonuclear number, markers of ribosome content, and satellite cell content (P<0.050). In response to ET, both groups similarly decreased body fat percentage (P<0.0001) and improved endurance performance (e.g. , and speed at which the onset of blood lactate accumulation occurred, P<0.0001). Levels of mitochondrial complexes I-IV in the ET-only group increased 32-66%, while those in the RT+ET group increased 1-11% (time, P<0.050). Additionally, mixed fibre relative mitochondrial content increased 15% in the ET-only group but decreased 13% in the RT+ET group (interaction, P=0.043). In conclusion, RT performed prior to ET had no additional benefits to ET adaptations. Moreover, prior RT seemed to impair mitochondrial adaptations to ET. KEY POINTS: Resistance training is largely underappreciated as a method to improve endurance performance, despite reports showing it may improve mitochondrial function. Although several concurrent training studies are available, in this study we investigated the effects of performing a period of resistance training on the performance and molecular adaptations to subsequent endurance training. Prior resistance training did not improve endurance performance and impaired most mitochondrial adaptations to subsequent endurance training, but this effect may have been a result of detraining from resistance training.

Longer-Term Effects of the Glycaemic Index on Substrate Metabolism and Performance in Endurance Athletes.

Nutrition has a decisive influence on athletic performance. However, it is not only the nutrient intake during exercise that is important, but the daily diet must also be adapted to the requirements of physical activity in order to optimally promote training adaptations. The goal of prolonged endurance training is to enhance fat oxidation, to maintain aerobic performance at a higher intensity while sparing limited carbohydrate stores. The targeted modification of macronutrient intake is a common method of influencing substrate metabolism, fuel selection, and performance. However, it is not well established whether the glycaemic index of carbohydrates in our daily diet can improve endurance performance by influencing carbohydrate or fat oxidation during training. Therefore, the aim of the following review is to elucidate the possible influence of the glycaemic index on substrate utilization during exercise and to clarify whether the consumption of a long-term high-carbohydrate diet with different glycaemic indices may have an influence on substrate metabolism and endurance performance.

591-P: Elite Cyclists with Type 1 Diabetes (T1D) Show Acceptable Glycemic Excursions during a Time-Trial Performance under High-Definition Transcranial Direct-Current Stimulation (HD-tDCS)

Patients with T1D are typically challenged by glycemic fluctuations during exercise. We recently applied HD-tDCS - a neuromodulation enhancer - both in healthy and T1D elite cyclists to improve endurance performance. Here, in a double-blind, counterbalanced, randomized order, nine elite cyclists (28 ± 3.5 years; BMI: 20.8 ± 1.3 kg/m2; VO2peak: 65.3 ± 1.7 mL/min/kg) with T1D (no complications) underwent either HD-tDCS (F3, F4) or control (SHAM) and completed a constant-load trial (CLT) at 75% of the 2nd ventilatory threshold plus a 15-km cycling time-trial (TT). Comparing the two conditions by real-time continuous glucose monitoring (CGM), subjects showed similar glycemic variability in any part of the session (Figure: bold line = mean; dotted lines = min &amp; max), with a significant effect of time (F=26.32; P&amp;lt;0.0001), but no interaction stimulation x time (F=0.08; P&amp;gt;0.99) nor effect of stimulation (F=0.077; P=0.79). Further, CGM data were stable for the 3 days preceding and following the tests. Given that glycemic control becomes of critical interest not only for health but also for performance goals, these findings suggest that HD-tDCS can be safely used as a performance improvement device in athletes with T1D, and possibly in a wider population of active T1D-subjects. Disclosure R.Codella: None. G.Gallo: None. A.Meloni: None. L.Luzi: Advisory Panel; Eli Lilly and Company, Medtronic, Research Support; Gelesis, Speaker's Bureau; A. Menarini Diagnostics, Amgen Inc., Boehringer Ingelheim and Eli Lilly Alliance, Eli Lilly and Company, Novo Nordisk, Novartis. L.Filipas: None.

266-LB: SGLT2 Inhibition Improved Endurance Performance of db/db Mice Accompanied by an Increased Endogenous AMPK Activator in Skeletal Muscles

Background: Diabetes is associated with loss of skeletal muscle mass and function. Specifically, diabetes may affect the function of oxidative muscle fibers with lower fatigability and higher oxidative capacity in skeletal muscle. The effects of SGLT2 inhibition on skeletal muscle metabolism and function in patients with type 2 diabetes remain unclear. Methods: Male db/db (diabetic) and db/+ (non-diabetic) mice at 8 weeks of age were fed a normal chow diet or a diet containing canagliflozin (CANA) for 4 weeks. Grip strength and running distance were assessed during CANA treatment. At the end of CANA treatment, we measured muscle weight and analyzed metabolites in skeletal muscle. Results: The weights of the oxidative soleus and glycolytic extensor digitorum longus muscles were reduced by approximately 50% in the diabetic group compared to the non-diabetic group, but neither was altered by CANA treatment. Grip strength did not differ between the CANA-treated diabetic, diabetic, and non-diabetic groups. However, the running distance decreased in the diabetic group compared to the non-diabetic group (89 ± 60 m vs. 1980 ± 276 m). This was partially restored by CANA treatment (89 ± 60 m vs. 415 ± 140 m). Metabolomic analysis revealed that long-chain acyl-CoA increased and medium-chain and short-chain acyl-CoA decreased in diabetic soleus muscle. In contrast, CANA treatment increased medium-chain and short-chain acyl-CoA. Furthermore, CANA increased 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranosyl 5’-monophosphate (AICARP), an endogenous AMPK activator, by approximately 3-fold in diabetic soleus muscle with increased levels of AMPK phosphorylation (Thr172). Conclusion: These results suggest that SGLT2 inhibitors may activate the AICARP/AMPK pathway and improve impaired oxidative muscle function in patients with type 2 diabetes. Disclosure S. Nakamura: None. Y. Miyachi: None. H. Yokomizo: None. H. Otsuka: None. R. Sakamoto: None. M. Takahashi: None. Y. Izumi: None. T. Miyazawa: None. T. Bamba: None. Y. Ogawa: None.

DMC (2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone) enhances exercise tolerance via the AMPK-SIRT1-PGC-1α pathway in mice fed a high-fat diet.

Obesity is caused by an imbalance between energy intake and energy expenditure. This study aimed to determine the effects and mechanisms of 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone (DMC) on exercise tolerance in high-fat diet (HFD)-fed mice. Male C57BL/6J mice were randomly divided into two categories (7 groups [n = 8]): sedentary (control [CON], HFD, 200 mg/kg DMC, and 500 mg/kg DMC) and swimming (HFD, 200 mg/kg DMC, and 500 mg/kg DMC). Except the CON group, all other groups were fed HFD with or without DMC intervention for 33 days. The swimming groups were subjected to exhaustive swimming (three sessions/week). Changes in swimming time, glucolipid metabolism, body composition, biochemical indicators, histopathology, inflammation, metabolic mediators, and protein expression were assessed. DMC combined with regular exercise improved endurance performance, body composition, glucose and insulin tolerance, lipid profile, and the inflammatory state in a dose-dependent manner. Further, DMC alone or combined with exercise could restore normal tissue morphology, reduce fatigue-associated markers, and boost whole-body metabolism and the protein expression of phospho-AMP-activated protein kinase alpha/total-AMP-activated protein kinase alpha (AMPK), sirtuin-1 (SIRT1), peroxisome-proliferator-activated receptor gamma coactivator 1alpha (PGC-1α), and peroxisome proliferator-activated receptor alpha in the muscle and adipose tissues of HFD-fed mice. DMC exhibits antifatigue effects by regulating glucolipid catabolism, inflammation, and energy homeostasis. Furthermore, DMC exerts a synergistic exercise-related metabolic effect via the AMPK-SIRT1-PGC-1α signaling pathway, suggesting that DMC is a potential natural sports supplement with mimicked or augmented exercise effects for obesity prevention.