Exhaustive Running Research Articles

Mechanical Deviations in Stride Characteristics During Running in the Severe Intensity Domain Are Associated With a Decline in Muscle Oxygenation.

We explored the impact of running in the severe intensity domain on running mechanics and muscle oxygenation in competitive runners by investigating the relationship between mechanical deviations from typical stride characteristics and muscle oxygen saturation (SmO2) in the quadriceps muscle. Sixteen youth competitive runners performed an 8-min exhaustive running test on an outdoor track. Running mechanics were continuously monitored using inertial measurement units. Rectus femoris SmO2 and total hemoglobin (a measure of blood volume) were continuously monitored by near-infrared spectroscopy. One-class support vector machine (OCSVM) modeling was employed for subject-specific analysis of the kinematic data. Statistical analysis included principal component analysis, ANOVA, and correlation analysis. Mechanical deviations from typical stride characteristics increased as the running test progressed. Specifically, the percentage of outliers in the OCSVM model rose gradually from 2.2 ± 0.8% at the start to 43.6 ± 28.2% at the end (p < 0.001, mean ± SD throughout). SmO2 dropped from 74.3 ± 8.4% at baseline to 10.1 ± 6.8% at the end (p < 0.001). A moderate negative correlation (r = -0.61, p = 0.013) was found between the average SmO2 and the percentage of outlier strides during the last 15% of the run. During high-intensity running, alterations in running biomechanics may occur, linked to decreased quadriceps muscle oxygenation. These parameters highlight the potential of using running kinematics and muscle oxygenation in training to optimize performance and reduce injury risks. Our research contributes to understanding biomechanical and physiological responses to endurance running and emphasizes the importance of individualized monitoring.

KLF13 restrains Dll4-muscular Notch2 axis to improve the muscle atrophy.

Muscle atrophy can cause muscle dysfunction and weakness. Krüppel-like factor 13 (KLF13), a central regulator of cellular energy metabolism, is highly expressed in skeletal muscles and implicated in the pathogenesis of several diseases. This study investigated the role of KLF13 in muscle atrophy, which could be a novel therapeutic target. The effects of gene knockdown and pharmacological targeting of KLF13 on skeletal muscle atrophy were investigated using cell-based and animal models. Clofoctol, an antibiotic and KLF13 agonist, was also investigated as a candidate for repurposing. The mechanisms related to skeletal muscle atrophy were assessed by measuring the expression levels and activation statuses of key regulatory pathways and validated using gene knockdown and RNA sequencing. In a dexamethasone-induced muscle atrophy mouse model, the KLF13 knockout group had decreased muscle strength (N) (1.77±0.10 vs. 1.48±0.16, P<0.01), muscle weight (%) [gastrocnemius (Gas): 76.0±5.69 vs. 60.7±7.23, P<0.001; tibialis anterior (TA): 75.8±6.21 vs. 67.5±5.01, P<0.05], and exhaustive running distance (m) (495.5±64.8 vs. 315.5±60.9, P<0.05) compared with the control group. KLF13 overexpression preserved muscle mass (Gas: 100±6.38 vs. 120±14.4, P<0.01) and the exhaustive running distance (423.8±59.04 vs. 530.2±77.45, P<0.05) in an in vivo diabetes-induced skeletal muscle atrophy model. Clofoctol treatment protected against dexamethasone-induced muscle atrophy. Myotubes treated with dexamethasone, an atrophy-inducing glucocorticoid, were aggravated by KLF13 knockout, but anti-atrophic effects were achieved by inducing KLF13 overexpression. We performed a transcriptome analysis and luciferase reporter assays to further explore this mechanism, finding that delta-like 4 (Dll4) was a novel target gene of KLF13. The KLF13 transcript repressed Dll4, inhibiting the Dll4-Notch2 axis and preventing muscle atrophy. Dexamethasone inhibited KLF13 expression by inhibiting myogenic differentiation 1 (i.e., MYOD1)-mediated KLF13 transcriptional activation and promoting F-Box and WD repeat domain containing 7 (i.e., FBXW7)-mediated KLF13 ubiquitination. This study sheds new light on the mechanisms underlying skeletal muscle atrophy and potential drug targets. KLF13 regulates muscle atrophy and is a potential therapeutic target. Clofoctol is an attractive compound for repurposing studies to treat skeletal muscle atrophy.

Kaempferol Improves Exercise Performance by Regulating Glucose Uptake, Mitochondrial Biogenesis, and Protein Synthesis via PI3K/AKT and MAPK Signaling Pathways.

Kaempferol is a natural flavonoid with reported bioactivities found in many fruits, vegetables, and medicinal herbs. However, its effects on exercise performance and muscle metabolism remain inconclusive. The present study investigated kaempferol's effects on improving exercise performance and potential mechanisms in vivo and in vitro. The grip strength, exhaustive running time, and distance of mice were increased in the high-dose kaempferol group (p < 0.01). Also, kaempferol reduced fatigue-related biochemical markers and increased the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) related to antioxidant capacity. Kaempferol also increased the glycogen and adenosine triphosphate (ATP) content in the liver and skeletal muscle, as well as glucose in the blood. In vitro, kaempferol promoted glucose uptake, protein synthesis, and mitochondrial function and decreased oxidative stress in both 2D and 3D C2C12 myotube cultures. Moreover, kaempferol activated the PI3K/AKT and MAPK signaling pathways in the C2C12 cells. It also upregulated the key targets of glucose uptake, mitochondrial function, and protein synthesis. These findings suggest that kaempferol improves exercise performance and alleviates physical fatigue by increasing glucose uptake, mitochondrial biogenesis, and protein synthesis and by decreasing ROS. Kaempferol's molecular mechanism may be related to the regulation of the PI3K/AKT and MAPK signaling pathways.

Subject-specific sensitivity of several biomechanical features to fatigue during an exhaustive treadmill run

The aim of the present study was to examine the sensitivity of several movement features during running to exhaustion in a subject-specific setup adopting a cross-sectional design and a machine learning approach. Thirteen recreational runners, that systematically trained and competed, performed an exhaustive running protocol on an instrumented treadmill. Respiratory data were collected to establish the second ventilatory threshold (VT2) in order to obtain a reference point regarding the gradual accumulation of fatigue. A machine learning approach was adopted to analyze kinetic and kinematic data recorded for each participant, using a random forest classifier for the region pre and post the second ventilatory threshold. SHapley Additive exPlanations (SHAP) analysis was used to explain the models’ predictions and to provide insight about the most important variables. The classification accuracy value of the models adopted ranged from 0.853 to 0.962. The most important feature in six out of thirteen participants was the angular range in AP axis of upper trunk C7 (RTAPu) followed by maximum loading rate (RFDmaxD) and the angular range in the LT axis of the C7. SHAP dependence plots also showed an increased dispersion of predictions in stages around the second ventilatory threshold which is consistent with feature interactions. These results showed that each runner used the examined features differently to cope with the increase in fatigue and mitigate its effects in order to maintain a proper motor pattern.

Metabolome and microbiome analyses of the anti-fatigue mechanism of Acanthopanax senticosus leaves.

Acanthopanax senticosus leaves, widely used as a vegetable and tea, are reported to be beneficial in treating neurological disorders. At present, their anti-fatigue effect remains to be established. In this study, we analyzed the composition of the extracts from A. senticosus leaves and confirmed their antioxidant and anti-inflammatory properties at the cellular level. In mice subjected to exhaustive running on a treadmill, supplementation with A. senticosus leaf extracts enhanced exercise performance and alleviated fatigue via the reversal of exercise-induced 5-HT elevation, metabolic waste accumulation, organ damage, and glucose metabolism-related gene expression. The collective findings from microbiome and metabolomic analyses indicate that A. senticosus leaf extracts increase α-diversity, regulate microbial composition, and reverse exercise-mediated disruption of carbohydrate, creatine, amino acid, and trimethylamine metabolism. This study provides preliminary evidence for the utility of A. senticosus leaves as a promising anti-fatigue food and offers insights into the underlying mechanism.

Interleukin-4 during post-exercise recovery negatively correlates with the production of phagocyte-generated oxidants.

Exhaustive run induced a biphasic oxidative response of circulating phagocytes in 16 amateur sportsmen. The first phase involved an increment just after exercise of enhanced whole blood chemiluminescence normalized per phagocyte count, whereas in the second phase a decrement from 1h post-exercise and ongoing till 24h. We tested whether plasma Interleukin IL-4, IL-8, IL-10 and Tumor Necrosis Factor α concentrations change in response to exhaustive run and whether there are associations between their levels and delta resting. Moreover, IL-8 and IL-10 significantly increased immediately post-exercise and after 1h, but later normalized. Tumor necrosis factor α rose by 1.1-times only just after exercise. However, none of these cytokines showed any correlation with the investigated chemiluminescence. Exercise did not alter plasma concentrations of IL-4. However, pre-exercise IL-4 negatively correlated with measured luminescence just after exercise (ρ = -0.54, p < 0.05), and also tended to be negatively associated with decrements of the second phase at 1h post-exercise ρ = -0.45, p = 0.08. It is suggested that plasma IL-4, by a negative association with blood phagocytes oxidants production, could be involved in the maintenance of proper balance between oxidants and anti-oxidants during strenuous exercise and post-exercise recovery.

Critical Velocity, Maximal Lactate Steady State, and Muscle MCT1 and MCT4 after Exhaustive Running in Mice.

Although the critical velocity (CV) protocol has been used to determine the aerobic capacity in rodents, there is a lack of studies that compare CV with maximal lactate steady state intensity (iMLSS) in mice. As a consequence, their physiological and molecular responses after exercise until exhaustion at CV intensity remain unclear. Thus, we aimed to compare and correlate CV with iMLSS in running mice, following different mathematical models for CV estimation. We also evaluated their physiological responses and muscle MCT1 and MCT4 after running until exhaustion at CV. Thirty C57BL/6J mice were divided into two groups (exercised-E and control-C). Group E was submitted to a CV protocol (4 days), using linear (lin1 and lin2) and hyperbolic (hyp) mathematical models to determine the distance, velocity, and time to exhaustion (tlim) of each predictive CV trial, followed by an MLSS protocol. After a running effort until exhaustion at CV intensity, the mice were immediately euthanized, while group C was euthanized at rest. No differences were observed between iMLSS (21.1 ± 1.1 m.min-1) and CV estimated by lin1 (21.0 ± 0.9 m.min-1, p = 0.415), lin2 (21.3 ± 0.9 m.min-1, p = 0.209), and hyp (20.6 ± 0.9 m.min-1, p = 0.914). According to the results, CV was significantly correlated with iMLSS. After running until exhaustion at CV (tlim = 28.4 ± 8,29 min), group E showed lower concentrations of hepatic and gluteal glycogen than group C, but no difference in the content of MCT1 (p = 0.933) and MCT4 (p = 0.123) in soleus muscle. Significant correlations were not found between MCT1 and MCT4 and tlim at CV intensity. Our results reinforce that CV is a valid and non-invasive protocol to estimate the maximal aerobic capacity in mice and that the content of MCT1 and MCT4 was not decisive in determining the tlim at CV, at least when measured immediately after the running effort.

The effects of alteration in muscle activation on the iliotibial band during an exhaustive run

PurposeLong exhausted running causes pain at the lateral femoral epicondyle for some runners. The pain has been revealed to be related to the behavior of the iliotibial band (ITB) during running. The purpose of this study is to examine the effects of in-series musculature on the behavior of the ITB in healthy participants during an exhaustive run.MethodsTwenty-five healthy participants (15 males, 10 females) were recruited in the current study. All participants performed a 30-minute exhaustive run at a self-selected speed with laboratory-provided footwear. Muscle activities of ITB-related muscles including tensor fascia latae (TFL), gluteus maximus (Gmax), gluteus medius (Gmed), biceps femoris (BF), and vastus lateralis (VL) were recorded using surface electromyography (EMG).ResultsMaximum amplitudes at the initial stage (the first minute), the mid stage (the 15-minute), and the end stage (the 30-minute) were compared during the exhaustive running. Significant decreases (p < 0.05) were observed in the maximum amplitudes of the TFL, Gmax, Gmed, and BF at the mid (decreased by ~ 15%) and end (decreased by ~ 30%) stages compared to the initial stage. The onset and the offset remained unaltered during the running (p ≥ 0.05).ConclusionThe behavior of the healthy ITB might be altered due to the activities of the in-series musculature. Excessive compression forces might be applied to the lateral femoral epicondyle from the ITB to provide stability for the knee joint during an exhaustive run. The findings could provide a basic understanding of the behavior of healthy ITB.

Faecal microbiota transplantation from young rats attenuates age-related sarcopenia revealed by multiomics analysis.

Gut microbiota plays a key role in the development of sarcopenia via the 'gut-muscle' axis, and probiotics-based therapy might be a strategy for sarcopenia. Fecal microbiota transplantation from young donors (yFMT) has attracted much attention because of its probiotic function. However, whether or not yFMT is effective for sarcopenia in old recipients is largely unknown. Thus, we aimed to investigate the effect and mechanism of yFMT on age-related sarcopenia. The fecal microbiota of either young (12weeks) or old (88weeks) donor rats was transplanted into aged recipient rats for 8weeks. Then, muscle mass, muscle strength, muscle function, muscle atrophy, and muscle regeneration capacity were measured. Analysis of fecal 16s rRNA, serum non-targeted metabolomic, gut barrier integrity, and muscle transcriptome was conducted to elucidate the interaction between gut microbiota and skeletal muscles. As evaluated by magnetic resonance imaging examination, grip strength test (P<0.01), rotarod test (P<0.05), and exhaustive running test (P<0.05), we found that yFMT mitigated muscle mass loss, muscle strength weakness, and muscle function impairment in aged rats. yFMT also countered age-related atrophy and poor regeneration capacity in fast- and slow-switch muscles, which were manifested by the decrease in slow-switch myofibres (both P<0.01) and muscle interstitial fibrosis (both P<0.05) and the increase in the cross-section area of myofibres (both P<0.001), fast-switch myofibres (both P<0.01), and muscle satellite cells (both P<0.001). In addition, yFMT ameliorated age-related dysbiosis of gut microbiota and metabolites by promoting the production of beneficial bacteria and metabolites-Akkermansia, Lactococcus, Lactobacillus, γ-glutamyltyrosine, 3R-hydroxy-butanoic acid, and methoxyacetic acid and inhibiting the production of deleterious bacteria and metabolites-Family_XIII_AD3011_group, Collinsella, indoxyl sulfate, indole-3-carboxilic acid-O-sulphate, and trimethylamine N-oxide. Also, yFMT prevented age-related destruction of gut barrier integrity by increasing the density of goblet cells (P<0.0001) and the expression levels of mucin-2 (P<0.0001) and tight junctional proteins (all P<0.05). Meanwhile, yFMT attenuated age-related impairment of mitochondrial biogenesis and function in fast- and slow-switch muscles. Correlation analysis revealed that yFMT-induced alterations of gut microbiota and metabolites might be closely related to mitochondria-related genes and sarcopenia-related phenotypes. yFMT could reshape the dysbiosis of gut microbiota and metabolites, maintain gut barrier integrity, and improve muscle mitochondrial dysfunction, eventually alleviating sarcopenia in aged rats. yFMT might be a new therapeutic strategy for age-related sarcopenia.

Mechanical energy on anaerobic capacity during a supramaximal treadmill running in men: Is there influence between runners and active individuals?

This study verified whether mechanical variables influence the anaerobic capacity outcome on treadmill running and whether these likely influences were dependent of running experience. Seventeen physical active and 18 amateur runners, males, performed a graded exercise test and constant load exhaustive running efforts at 115% of intensity associated to maximal oxygen consumption. During the constant load were determined the metabolic responses (i.e., gas exchange and blood lactate) to estimate the energetic contribution and anaerobic capacity as well as kinematic responses. The runners showed higher anaerobic capacity (16.6%; p=0.005), but lesser time to exercise failure (-18.8%; p=0.03) than active subjects. In addition, the stride length (21.4%; p=0.00001), contact phase duration (-11.3%; p=0.005), and vertical work (-29.9%; p=0.015). For actives, the anaerobic capacity did not correlate significantly with any physiologic, kinematic, and mechanical variables and no regression model was fitted using the stepwise multiple regression, while to runners the anaerobic capacity was significantly correlated with phosphagen energetic contribution (r=0.47; p=0.047), external power (r=-0.51; p=0.031), total work (r=-0.54; p=0.020), external work (r=-0.62; p=0.006), vertical work (r=-0.63; p=0.008), and horizontal work (r=-0.61; p=0.008), and the vertical work and phosphagen energetic contribution presented a coefficient of determination of 62% (p=0.001). Based on findings, it is possible to assume that for active subjects, the mechanical variables have no influence over the anaerobic capacity, however, for experienced runners, the vertical work and phosphagen energetic contribution have relevant effect over anaerobic capacity output.

The effect of fatigue on the ankle and knee kinematics and kinetics in moderately and highly trained healthy non-rearfoot runners

ABSTRACT The aim of this study was to compare selected ankle and knee kinematic and kinetic parameters before and after a prolonged exhaustive treadmill run between two groups of non-rearfoot footstrike pattern (NRFP) runners with different training volumes. Twenty-eight habitual NRFP runners were assigned to two groups based on their weekly training volume (Highly-trained (HT)/Moderately-trained (MT)). Participants underwent the VO2max test, and the exhaustive treadmill ran with biomechanical analysis at the beginning and the end. The two-way RMANOVA was used to assess differences between the groups and the phase of the run. A paired t-test was used for post-hoc analysis in case of significant interaction effect. Kinetic results showed significant group effect for ankle plantarflexion moment and hip external rotation moment (end-phase: both greater in MT group). Kinematic results showed significant group×phase interaction for ankle dorsiflexion angle (end-phase: greater in MT group) at initial contact (IC), peak knee flexion angle (end-phase: greater in MT group), and peak ankle eversion angle during the stance phase (end-phase: greater in HT group). Additionally, a group effect was found for knee flexion angle at IC (end-phase: greater in HT group). This study suggests that HT healthy NRFP runners may have less potential for increased biomechanical risk of AT overload during an exhaustive run.

L-menthol administration facilitates breathing comfort during exhaustive endurance running and improves running capacity in well-trained runners: A randomized crossover study

ABSTRACT This study aimed to clarify the contribution of L-menthol administration to endurande exercise capacity. Thirteen male runners (age, 35.8 ± 7.8 years; peak oxygen uptake, 62.7 ± 6.8 mL kg−1 min−1) ran on treadmills at fixed intensities of their anaerobic thresholds to exhaustion. All participants underwent three trials—water ingestion (W-IG), L-menthol mouth rinsing (M-MR), and L-menthol ingestion (M-IG)— in a random order every 5 min while running. Breathing comfort (BC) was measured immediately after fluid intake. Dyspnea threshold against external inspiratory resistance was examined before and after the running test. The running time with M-IG (1683.9 ± 520.3 s) was longer than that with W-IG (1410.2 ± 465.9 s, effect size [ES] = 0.55). BC with M-IG (2.00 ± 0.74) was higher than that with W-IG (0.42 ± 0.79) at exhaustion (ES > 2.00). The dyspnea threshold after running decreased to 19.2 ± 7.6 cm H₂O L−1 s−1 with W-IG, whereas that with M-MR (26.2 ± 6.5 cm H₂O L−1 s−1) and M-IG (29.2 ± 2.8 cm H₂O L−1 s−1) remained high (p for interaction < 0.001). M-IG facilitated BC during running, improved endurance capacity, and prevented decreases in the dyspnea threshold against external inspiratory resistance after exhaustive running. Highlights L-menthol ingestion facilitated breathing comfort during high intensity endurance running and improved exhaustive endurance running capacity. Even after exhaustion, L-menthol solution relieved dyspnea sensitivity against external inspiratory resistance. L-menthol ingestion might help athletes improve their endurance running capacity.

Does the Achilles Tendon Influence Foot Strike Patterns During an Exhaustive Run?

The study purpose was to investigate whether there is a relationship between the Achilles tendon (AT) length, moment arm length, and the foot strike pattern (FP) change during an exhaustive run (EXR) in nonrearfoot FP runners. Twenty-eight runners were recruited and divided into 2 groups (highly trained/moderately trained) according to their weekly training volume. Participants underwent the graded exercise test, the EXR with biomechanical analysis at the beginning, and at the end, and the magnetic resonance imaging scan of the AT. Correlations were used to assess associations between FP change (value of the difference between end and beginning) and the selected performance and AT variables. AT length significantly correlated with the FP change according to foot strike angle (r = -.265, P = .049). The AT moment arm length significantly correlated with the FP change according to strike index during EXR (r = -.536, P = .003). Multiple regression showed that AT length was a significant predictor for the FP change according to foot strike angle if the second predictor was the graded exercise test duration and the third predictor was training group association. These results suggest that a runner's training volume, along with a longer AT and AT moment arm appear to be associated with the ability to maintain a consistent FP during EXR by nonrearfoot FP runners.

Effect of clove on improving running ability in aging mice.

In this study, a D-galactose-induced aging mouse model was established, and Syringa oblata Lindl. extract (SOLE) was administered orally to observe the effect and mechanism of SOLE on the running ability of aging mice. The role of SOLE was evaluated by H&E histopathological observation, detection of serum biochemical indices, and detection of mRNA expression levels by qPCR experiments. The experimental results showed that SOLE could increase the exhaustive running time of aging mice and reduce the oxidative aging of the liver and kidney. At the same time, the levels of BUN, lactic acid, GOT, GPT, MDA, iNOS, and TNF-α in the serum of the mice were decreased, and the relative mRNA expression levels of nNOS, iNOS, TNF-α and syncytin-1 in the liver tissue and skeletal muscle tissue of the mice were downregulated. In addition, it increased the levels of CAT, GSH-Px, and T-SOD in mouse serum and upregulated the relative mRNA expression of Cu/Zn-SOD, Mn-SOD, and CAT in mouse liver tissue and muscle tissue. The analysis results showed that SOLE mainly contained rutin, isoquercitrin, ferulic acid, dihydroquercetin, and quercitrin. In summary, SOLE can enhance the running ability and exercise ability of aging mice and slow down aging. PRACTICAL APPLICATIONS: Clove is used as health tea or traditional Chinese medicine in China, but there is no relevant research and application on the improvement of human exercise ability. This study found this new function of clove, which accumulated a theoretical basis for further popularizing its application.

Repeated low-dose caffeine ingestion during a night of total sleep deprivation improves endurance performance and cognitive function in young recreational runners: A randomized, double-blind, placebo-controlled study

ABSTRACT The present study aimed to assess the effects of repeated administration of low-dose caffeine during a night of total sleep deprivation on physical and cognitive performance. Twelve recreational runners (being non-habitual caffeine users) performed four test sessions in a double-blind randomized order after (i) a placebo or 6 mg/kg of caffeine ingestion during a baseline night (BN) or (ii) a placebo or three doses of 2 mg/kg of caffeine during a night of total sleep deprivation (TSD). At each session, they completed an exhaustive run at 75% of the final velocity in a Vameval test (Vvameval) around a 400 m outdoor athletics track and performed the correct detection and reaction time tasks. In comparison with BN, the TSD condition significantly impaired running performance, reaction time, and correct detections. On the contrary, caffeine intake improved exhaustive running performance after BN by 5.2% (p < .001) and after TSD by 8.9% (p < .001), increased correct detections after BN (p < .05) and TSD (p < .05), and decreased reaction time after BN (p < .01) and TSD (p < .05) compared to placebo. Therefore, the repeated ingestion of low-dose caffeine is an effective strategy to counteract the detrimental effects of total sleep deprivation on physical and cognitive performance.

Combined effects of exercise training and D-allulose intake on endurance capacity in mice.

This study investigated the combined effects of exercise training and D‐allulose intake on endurance capacity in mice. Male C57BL/6J mice were fed either a control diet (Con) or a 3% D‐allulose diet (Allu) and further divided into the sedentary (Sed) or exercise training (Ex) groups (Con‐Sed, Con‐Ex, Allu‐Sed, Allu‐Ex, respectively; n = 6–7/group). The mice in the Ex groups were trained on a motor‐driven treadmill 5 days/week for 4 weeks (15–18 m/min, 60 min). After the exercise training period, all mice underwent an exhaustive running test to assess their endurance capacity. At 48 h after the running test, the mice in the Ex groups were subjected to run at 18 m/min for 60 min again. Then the gastrocnemius muscle and liver were sampled immediately after the exercise bout. The running time until exhaustion tended to be higher in the Allu‐Ex than in the Con‐Ex group (p = 0.08). The muscle glycogen content was significantly lower in the Con‐Ex than in the Con‐Sed group and was significantly higher in the Allu‐Ex than in the Con‐Ex group (p < 0.05). Moreover, exercise training increased the phosphorylation levels of adenosine monophosphate‐activated protein kinase (AMPK) in the muscle and liver. The phosphorylation levels of acetyl coenzyme A carboxylase (ACC), a downstream of AMPK, in the muscle and liver were significantly higher in the Allu‐Ex than in the Con‐Sed group (p < 0.05), suggesting that the combination of exercise training and D‐allulose might have activated the AMPK‐ACC signaling pathway, which is associated with fatty acid oxidation in the muscle and liver. Taken together, our data suggested the combination of exercise training and D‐allulose intake as an effective strategy to upregulate endurance capacity in mice. This may be associated with sparing glycogen content and enhancing activation of AMPK‐ACC signaling in the skeletal muscle.

Probiotic Strains Isolated from an Olympic Woman's Weightlifting Gold Medalist Increase Weight Loss and Exercise Performance in a Mouse Model.

Obesity is a worldwide health problem. Calorie-restricted diets constitute a common intervention for treating obesity. However, an improper calorie-restricted diet can lead to malnutrition, fatigue, poor concretion, muscle loss, and reduced exercise performance. Probiotics have been introduced as an alternative treatment for obesity. In the present study, we tested the weight loss and exercise performance enhancement effectiveness of probiotic strains of different origins, including four isolated from an Olympic weightlifting gold medalist (Bifidobacterium longum subsp. longum OLP-01, Lactobacillus plantarum PL-02, Lactobacillus salivarius subsp. salicinius SA-03, and Lactococcus lactis subsp. lactis LY-66). A high-fat diet (HFD) was used to induce obesity in 16 groups of mice (n = 8/group). The mice were administered probiotic supplements at a dosage of 4.1 × 109 CFU/kg/day for 10 weeks. All probiotic supplementation groups showed a significant reduction in body weight and fat mass compared with the HFD group. TYCA06, CS-773, BLI-02, PL-02, bv-77, and OLP-01 were the most effective in facilitating weight loss and fat reduction, which may be due to fatty-acid absorbing activity. PL-02, LY-66, TYCA06, CS-773, and OLP-01 elevated the animals’ grip strength and exhaustive running duration. PL-02, LY-66, and OLP-01 increased tissue glycogen (liver and muscle) levels and muscle capillary density and reduced blood lactate production levels after exercise. In conclusion, OLP-01, PL-02, LY-66, TYCA06, and CS-773 were highly effective in enhancing weight loss and exercise performance. This study should be repeated on humans in the future to further confirm the findings.

Effects of Repeated Low-dose Caffeine Ingestion During a Night of Total Sleep Deprivation on Physical Performance and Psychological State in Young Recreational Runners

Background: Caffeine is frequently consumed by athletes to maintain alertness in conditions of sleep loss. However, the effect of caffeine ingestion during total sleep deprivation during aerobic exercise remains questionable. Objectives: The present study aimed to assess the effects of repeated intake of low-dose caffeine during a night of total sleep deprivation on endurance performance and psychological states. Methods: Twelve recreational runners performed four test sessions in a double-blind randomized order after a placebo or 6 mg/kg of caffeine ingestion after a baseline night (BN) or three doses of 2 mg/kg of caffeine during a night of total sleep deprivation (TSD). At each session, they completed an exhaustive run around a 400 m athletics track and performed the Feeling Scale test. ANOVA with repeated measures followed by paired t-tests was used to analyze the data. Results: In comparison with BN, the TSD condition significantly impaired running performance (P &lt; 0.001). On the contrary, caffeine administration improved endurance running performance (P &lt; 0.001) and increased feeling of well-being (P &lt; 0.05) after TSD night as compared to placebo. Conclusions: Repeated ingestion of low-dose caffeine is an effective way to mitigate the negative effects of total sleep deprivation on endurance performance and mood states.

Hypoxia Improves Endurance Performance by Enhancing Short Chain Fatty Acids Production via Gut Microbiota Remodeling.

Hypoxia environment has been widely used to promote exercise capacity. However, the underlying mechanisms still need to be further elucidated. In this study, mice were exposed to the normoxia environment (21% O2) or hypoxia environment (16.4% O2) for 4 weeks. Hypoxia-induced gut microbiota remodeling characterized by the increased abundance of Akkermansia and Bacteroidetes genera, and their related short-chain fatty acids (SCFAs) production. It was observed that hypoxia markedly improved endurance by significantly prolonging the exhaustive running time, promoting mitochondrial biogenesis, and ameliorating exercise fatigue biochemical parameters, including urea nitrogen, creatine kinase, and lactic acid, which were correlated with the concentrations of SCFAs. Additionally, the antibiotics experiment partially inhibited hypoxia-induced mitochondrial synthesis. The microbiota transplantation experiment demonstrated that the enhancement of endurance capacity induced by hypoxia was transferable, indicating that the beneficial effects of hypoxia on exercise performance were partly dependent on the gut microbiota. We further identified that acetate and butyrate, but not propionate, stimulated mitochondrial biogenesis and promoted endurance performance. Our results suggested that hypoxia exposure promoted endurance capacity partially by the increased production of SCFAs derived from gut microbiota remodeling.

Effects of two low-volume high-intensity interval training protocols in professional soccer: sprint interval training versus small-sided games.

The programming of training protocols within a high-intensity interval training (HIIT) framework with appropriate analysis of total training load could deliver optimal training adaptations. This study aims to compare the efficiency of two low-volume HIIT protocols integrated with the regular training regime in professional soccer players. Twenty-five participants aged 18.4-29.7 years were randomly assigned to one of two interventions involving straight-line sprint interval training (SIT, N.=13) or small-sided games (SSG, N.=12). Periodization was divided into two 3-week phases concluded by a 7-day taper. SIT first involved two-session·week-1 of one set of 10·45-s sprints (at maximal intensity) and then three-session·week-1 of two sets of 10·30-s sprints with a 0.75:1 and 1:1 recovery interval (slow running and stretching exercises), respectively. SSG in the first phase involved 5·3-min games of 4 vs. 4 and in the second phase 4·4-min games of 2 vs. 2 with 3-min recovery (practice drills at 60-70% HR<inf>max</inf>). Training load was controlled via session-RPE and HR-based methods. Pre- and postintervention testing included: countermovement jump height, 5-m and 30-m sprints performance, anaerobic power by the 10-s Wingate Anaerobic Test, maximal oxygen uptake (V̇O<inf>2max</inf>) and blood lactate concentration (BLa-) determined by incremental exhaustive running test. Two-way ANOVA showed group×time interaction effects for the 30-m sprint time (F<inf>(1,23)</inf>=3.023; P=0.049; η2 P=0.116), BLa- (F<inf>(1,23)</inf>=5.250; P=0.031; η2 P=0.185), and V̇O<inf>2max</inf> (F<inf>(1,23)=</inf>4.648, P=0.044; η2 P=0.157). SIT elicited greater enhancements in anaerobic performance (30-m sprint time and BLa-), while SSG induced larger improvements in V̇O<inf>2max</inf>. Comparable effects of SIT and SSG protocols were noted, however the aerobic capacity benefits provided by SSG warrant this HIIT protocol as a highly recommended training modality in the professional soccer.