Single Bout Of Resistance Exercise Research Articles

A single bout of resistance exercise triggersmitophagy, potentially involving the ejection of mitochondria in human skeletal muscle.

The present study aimed to investigate the effects of a single bout of resistance exercise on mitophagy in human skeletal muscle (SkM). Eight healthy men were recruited to complete an acute bout of one-leg resistance exercise. SkM biopsies were obtained one hour after exercise in the resting leg (Rest-leg) and the contracting leg (Ex-leg). Mitophagy was assessed using protein-related abundance, transmission electron microscopy (TEM), and fluorescence microscopy. Our results show that acute resistance exercise increased pro-fission protein phosphorylation (DRP1Ser616) and decreased mitophagy markers such as PARKIN and BNIP3L/NIX protein abundance in the Ex-leg. Additionally, mitochondrial complex IV decreased in the Ex-leg when compared to the Rest-leg. In the Ex-leg, TEM and immunofluorescence images showed mitochondrial cristae abnormalities, a mitochondrial fission phenotype, and increased mitophagosome-like structures in both subsarcolemmal and intermyofibrillar mitochondria. We also observed increased mitophagosome-like structures on the subsarcolemmal cleft and mitochondria in the extracellular space of SkM in the Ex-leg. We stimulated human primary myotubes with CCCP, which mimics mitophagy induction in the Ex-leg, and found that BNIP3L/NIX protein abundance decreased independently of lysosomal degradation. Finally, in another human cohort, we found a negative association between BNIP3L/NIX protein abundance with both mitophagosome-like structures and mitochondrial cristae density in the SkM. The findings suggest that a single bout of resistance exercise can initiate mitophagy, potentially involving mitochondrial ejection, in human skeletal muscle. BNIP3L/NIX is proposed as a sensitive marker for assessing mitophagy flux in SkM.

Coingestion of Collagen With Whey Protein Prevents Postexercise Decline in Plasma Glycine Availability in Recreationally Active Men.

Whey protein ingestion during recovery from exercise increases myofibrillar but not muscle connective protein synthesis rates. It has been speculated that whey protein does not provide sufficient glycine to maximize postexercise muscle connective protein synthesis rates. In the present study, we assessed the impact of coingesting different amounts of collagen with whey protein as a nutritional strategy to increase plasma glycine availability during recovery from exercise. In a randomized, double-blind, crossover design, 14 recreationally active men (age: 26 ± 5years; body mass index: 23.8 ± 2.1kg·m-2) ingested in total 30g protein, provided as whey protein with 0g (WHEY), 5g (WC05); 10g (WC10), and 15g (WC15) of collagen protein immediately after a single bout of resistance exercise. Blood samples were collected frequently over 6hr of postexercise recovery to assess postprandial plasma amino acid kinetics and availability. Protein ingestion strongly increased plasma amino acid concentrations (p < .001) with no differences in plasma total amino acid availability between treatments (p > .05). The postprandial rise in plasma leucine and essential amino acid availability was greater in WHEY compared with the WC10 and WC15 treatments (p < .05). Plasma glycine and nonessential amino acid concentrations declined following whey protein ingestion but increased following collagen coingestion (p < .05). Postprandial plasma glycine availability averaged -8.9 ± 5.8, 9.2 ± 3.7, 23.1 ± 6.5, and 39.8 ± 11.0mmol·360min/L in WHEY, WC05, WC10, and WC15, respectively (incremental area under curve values, p < .05). Coingestion of a small amount of collagen (5g) with whey protein (25g) is sufficient to prevent the decline in plasma glycine availability during recovery from lower body resistance-type exercise in recreationally active men.

The Influence of Aging on the Unfolded Protein Response in Human Skeletal Muscle at Rest and after Acute Exercise.

The unfolded protein response (UPR) is a proteostatic process that is activated in response to endoplasmic reticulum stress. It is currently unclear how aging influences the chronic and adaptive UPR in human skeletal muscle. Here we determined the effect of aging on UPR activation at rest, in response to exercise, and the associations with muscle function. Thirty young (20-35 yr) and 50 older (65-85 yr) individuals were enrolled. Vastus lateralis biopsies were performed at rest and 3 and 48 h after a single bout of resistance exercise. The abundance of UPR-related transcripts and proteins was measured by RNA sequencing and Western blotting, respectively. Fractional synthetic rates of muscle protein were determined by mass spectrometry after intravenous infusion of 13 C 6 phenylalanine. Older adults demonstrated elevated transcriptional and proteomic markers of UPR activation in resting muscle. Resting UPR gene expression was negatively associated with muscle strength and power in older adults. The UPR is similarly activated by acute resistance exercise in young and older adults and positively associated with muscle function but not the anabolic response to exercise. Skeletal muscle from older adults exhibits chronically activated UPR, which accompanies functional decline. The adaptive UPR is a proteostatic mechanism that is upregulated in response to exercise in young and older adults and positively associated with muscle function.

Effect of 60-Min Single Bout of Resistance Exercise, Reformer Pilates, on Vascular Function Parameters in Older Adults: A Randomized Crossover Study

Introduction: Aging leads to vascular endothelial dysfunction and muscle impairment. While resistance exercise improves muscular function, its acute effects on vascular function vary in the literature, with some studies reporting detrimental effects. These findings indicate the need for exercises that optimize muscle function without compromising vascular function. Reformer Pilates (RP) is a low-impact exercise involving an adjustable sliding platform. However, the acute effects of RP on vascular function among older adults remain unknown. Therefore, this study aimed to investigate the acute effects of RP on vascular function in older adults. Methods: Overall, 17 participants (age: 65 ± 2.76 years, body mass index: 23.42 ± 3.68 kg/m2) were examined and assigned to control and RP conditions under a randomized crossover design. The RP condition involved a 3.5–5 omnibus perceived exertion scale with 19 exercise postures for 60 min. Brachial artery flow-mediated dilation (FMD), brachial-ankle pulse wave velocity (baPWV), and blood pressure were measured at baseline and 0, 10, 30, and 60 min after exercise. Results: RP significantly improved FMD at all time points compared with that at baseline (p < 0.05). baPWV increased at 0 min post-RP but returned to baseline levels at other time points. Additionally, RP showed improved FMD at 0, 10, and 30 min compared with that in the control condition (p < 0.05). However, no significant differences were observed in blood pressure or mean arterial pressure in either condition. Conclusion: RP enhanced FMD and regulated blood pressure for approximately 60 min post-exercise, suggesting its suitability for older adults to enhance vascular function and control blood pressure during exercise. Nonetheless, longitudinal resistance training intervention studies are needed to validate these findings.

Making the case for resistance training in improving vascular function and skeletal muscle capillarization.

Through decades of empirical data, it has become evident that resistance training (RT) can improve strength/power and skeletal muscle hypertrophy. Yet, until recently, vascular outcomes have historically been underemphasized in RT studies, which is underscored by several exercise-related reviews supporting the benefits of endurance training on vascular measures. Several lines of evidence suggest large artery diameter and blood flow velocity increase after a single bout of resistance exercise, and these events are mediated by vasoactive substances released from endothelial cells and myofibers (e.g., nitric oxide). Weeks to months of RT can also improve basal limb blood flow and arterial diameter while lowering blood pressure. Although several older investigations suggested RT reduces skeletal muscle capillary density, this is likely due to most of these studies being cross-sectional in nature. Critically, newer evidence from longitudinal studies contradicts these findings, and a growing body of mechanistic rodent and human data suggest skeletal muscle capillarity is related to mechanical overload-induced skeletal muscle hypertrophy. In this review, we will discuss methods used by our laboratories and others to assess large artery size/function and skeletal muscle capillary characteristics. Next, we will discuss data by our groups and others examining large artery and capillary responses to a single bout of resistance exercise and chronic RT paradigms. Finally, we will discuss RT-induced mechanisms associated with acute and chronic vascular outcomes.

β2-Adrenoceptors activation regulates muscle trophic-related genes following acute resistance exercise in mice.

Resistance exercise (RE) training and pharmacological stimulation of β2-Adrenoceptors (β2-ARs) alone can promote muscle hypertrophy and prevent muscle atrophy. Although the activation of the sympathetic nervous system (SNS) is a well-established response during RE, the physiological contribution of the endogenous catecholamines and β2-ARs to the RE-induced changes on skeletal muscle protein metabolism remains unclear. This study investigated the effects of the β2-ARs blockade on the acute molecular responses induced by a single bout of RE in rodent skeletal muscles. Male C57BL6/J mice were subjected to a single bout of progressive RE (until exhaustion) on a vertical ladder under β2-AR blockade with ICI 118,551 (ICI; 10mgkg-1, i. p.), or vehicle (sterile saline; 0.9%, i. p.), and the gene expression was analyzed in gastrocnemius (GAS) muscles by qPCR. We demonstrated that a single bout of RE acutely increased the circulating levels of stress-associated hormones norepinephrine (NE) and corticosterone (CORT), as well as the muscle phosphorylation levels of AMPK, p38 MAPK and CREB, immediately after the session. The acute increase in the phosphorylation levels of CREB was followed by the upregulation of CREB-target genes Sik1, Ppargc1a and Nr4a3 (a central regulator of the acute RE response), 3h after the RE session. Conversely, β2-AR blockade reduced significantly the Sik1 and Nr4a3 mRNA levels in muscles of exercised mice. Furthermore, a single bout of RE stimulated the mRNA levels of the atrophic genes Map1lc3b and Gabarapl1 (autophagy-related genes) and Mstn (a well-known negative regulator of muscle growth). Unexpectedly, the gene expression of Igf-1 or Il-6 were not affected by RE, while the atrophic genes Murf1/Trim63 and Atrogin-1/Mafbx32 (ubiquitin-ligases) were increased only in muscles of exercised mice under β2-AR blockade. Interestingly, performing a single bout of RE under β2-AR blockade increased the mRNA levels of Mstn in muscles of exercised mice. These data suggest that β2-ARs stimulation during acute RE stimulates the hypertrophic gene Nr4a3 and prevents the overexpression of atrophic genes such as Mstn, Murf1/Trim63, and Atrogin-1/Mafbx32 in the first hours of postexercise recovery, indicating that he SNS may be physiologically important to muscle adaptations in response to resistance training.

A single bout of prior resistance exercise attenuates muscle atrophy and declines in myofibrillar protein synthesis during bed-rest in older men.

Impairments in myofibrillar protein synthesis (MyoPS) during bed rest accelerate skeletal muscle loss in older adults, increasing the risk of adverse secondary health outcomes. We investigated the effect of prior resistance exercise (RE) on MyoPS and muscle morphology during a disuse event in 10 healthy older men (65-80years). Participants completed a single bout of unilateral leg RE the evening prior to 5days of in-patient bed-rest. Quadriceps cross-sectional area (CSA) was determined prior to and following bed-rest. Serial muscle biopsies and dual stable isotope tracers were used to determine rates of integrated MyoPS (iMyoPS) over a 7day habitual 'free-living' phase and the bed-rest phase, and rates of acute postabsorptive and postprandial MyoPS (aMyoPS) at the end of bed rest. Quadriceps CSA at 40%, 60% and 80% of muscle length significantly decreased in exercised (EX) and non-exercised control (CTL) legs with bed-rest. The decline in quadriceps CSA at 40% and 60% of muscle length was attenuated in EX compared with CTL. During bed-rest, iMyoPS rates decreased from habitual values in CTL, but not EX, and were significantly different between legs. Postprandial aMyoPS rates increased above postabsorptive values in EX only. The change in iMyoPS over bed-rest correlated with the change in quadriceps CSA in CTL, but not EX. A single bout of RE attenuated the decline in iMyoPS rates and quadriceps atrophy with 5days of bed-rest in older men. Further work is required to understand the functional and clinical implications of prior RE in older patient populations. KEY POINTS: Age-related skeletal muscle deterioration, linked to numerous adverse health outcomes, is driven by impairments in muscle protein synthesis that are accelerated during periods of disuse. Resistance exercise can stimulate muscle protein synthesis over several days of recovery and therefore could counteract impairments in this process that occur in the early phase of disuse. In the present study, we demonstrate that the decline in myofibrillar protein synthesis and muscle atrophy over 5days of bed-rest in older men was attenuated by a single bout of unilateral resistance exercise performed the evening prior to bed-rest. These findings suggest that concise resistance exercise intervention holds the potential to support muscle mass retention in older individuals during short-term disuse, with implications for delaying sarcopenia progression in ageing populations.

The Effect of Strawberry Extract Supplementation on Caspase -3 and Cytochrome C After Resistance Exercise in Non-athletic Women

Background: Exercise-induced apoptosis occurs in a variety of tissues. Objectives: This study aimed to determine the effects of strawberry extract supplementation on circulating apoptosis biomarkers following a single bout of resistance exercise. Methods: Eighteen healthy young untrained women were enrolled in a randomized, double-blind, placebo-controlled crossover research. The subjects participated in one resistance exercise session (at 80% 1RM) and underwent 2 wk strawberry extracts (700 mg daily) or maltodextrin. The washout period that separated the treatment periods was 4 wk. Blood samples were taken before supplementation and after 2 wk of the post-resistance exercise session to determine cytochrome c and caspase-3 serum markers. Results: Resting cytochrome c and caspase-3 concentrations were not significantly different for any strawberry extract supplementation and placebo groups (P &gt; 0.05). Cytochrome c and caspase-3 were significantly elevated after exercise in a placebo (P &lt; 0.05) but not strawberry extract supplementation. Conclusions: Supplementation with strawberry extract attenuates intense acute exercise-induced apoptosis in healthy women.

Interrelated but Not Time-Aligned Response in Myogenic Regulatory Factors Demethylation and mRNA Expression after Divergent Exercise Bouts.

DNA methylation regulates exercise-induced changes in the skeletal muscle transcriptome. However, the specificity and the time course responses in the myogenic regulatory factors DNA methylation and mRNA expression after divergent exercise modes are unknown. This study aimed to compare the time course changes in DNA methylation and mRNA expression for selected myogenic regulatory factors ( MYOD1 , MYF5 , and MYF6 ) immediately after, 4 h after, and 8 h after a single bout of resistance exercise (RE), high-intensity interval exercise (HIIE), and concurrent exercise (CE). Nine healthy but untrained males (age, 23.9 ± 2.8 yr; body mass, 70.1 ± 14.9 kg; peak oxygen uptake [V̇O 2peak ], 41.4 ± 5.2 mL·kg -1 ·min -1 ; mean ± SD) performed a counterbalanced, randomized order of RE (4 × 8-12 repetition maximum), HIIE (12 × 1 min sprints at V̇O 2peak running velocity), and CE (RE followed by HIIE). Skeletal muscle biopsies (vastus lateralis) were taken before (REST) immediately (0 h), 4 h, and 8 h after each exercise bout. Compared with REST, MYOD1 , MYF5 , and MYF6 , mean methylation across all CpGs analyzed was reduced after 4 and 8 h in response to all exercise protocols ( P < 0.05). Reduced levels of MYOD1 methylation were observed after HIIE and CE compared with RE ( P < 0.05). Compared with REST, all exercise bouts increased mRNA expression over time ( MYOD1 at 4 and 8 h, and MYF6 at 4 h; P < 0.05). MYF5 mRNA expression was lower after 4 h compared with 0 h and higher at 8 h compared with 4 h ( P < 0.05). We observed an interrelated but not time-aligned response between the exercise-induced changes in myogenic regulatory factors demethylation and mRNA expression after divergent exercise modes. Despite divergent contractile stimuli, changes in DNA methylation and mRNA expression in skeletal muscle were largely confined to the late (4-8 h) recovery period and similar between the different exercise challenges.

The effect of resistance exercise on the immune cell function in humans: A systematic review.

Resistance exercise is beneficial for the immune system, including decreased susceptibility to infections and improved effectiveness of vaccinations. This review aims to provide a systematic analysis of the literature regarding the impact of resistance exercise on immune cells in the blood circulation. The protocol of this review followed the PRISMA guidelines and registered in PROSPERO (ID: CRD42020157834). PubMed and Web-of-Science were systematically searched for relevant articles. Outcomes were divided into two categories: 1) inflammatory gene expression or secretion of inflammation-related cytokines and 2) other aspects such as cell migration, proliferation, apoptosis, phagocytosis, and redox status. Thirty intervention studies were included in this review, of which 11 articles were randomized controlled trials and six non-randomized controlled trials. Although only resistance exercise interventions were included, there was a high heterogeneity regarding specific exercise modalities. The most frequently studied outcome measures were the gene and protein expression levels in peripheral blood mononuclear cells (PBMC). This review reveals that already one acute exercise bout activates the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway in PBMC. Although resistance exercise induces an acute cytosolic oxidative stress response, the antioxidant enzyme expression is improved after resistance training period. Natural killer cell activity increases in older but decreases in younger adults immediately after a resistance exercise bout. Moreover, resistance exercise improves neutrophil phagocytic activity. Finally, effects on lymphocyte proliferation remain unclear. The results of this systematic review demonstrate that resistance exercise has beneficial effects on several aspects of immune cell function both in young and older individuals. Acute changes in immune cell function occur already after a single bout of resistance exercise. However, regular resistance training during several weeks seems necessary to obtain beneficial adaptations that can be related to better immunity and reduced inflammation. The effects documented in this review confirm the beneficial effects of resistance exercise in young as well as older persons on the immune cell function.

Impact of Obesity on Exercise‐Induced Skeletal Muscle Exosomes

Exosomes are small extracellular vesicles (EVs) that can function as effective delivery vehicles through systemic circulation due to the protective effects of the phospholipid bilayer. Our previous work in mice indicated that resistance exercise induces the release of skeletal muscle EVs to promote adipose lipolysis through the action of microRNA‐1. To better understand the effect of resistance exercise on exosomes in humans, we collected blood samples as well as skeletal muscle and adipose tissue biopsies before and after a single bout of resistance exercise. Using the ExoView platform, we were able to analyze subpopulations of exosomes based on their surface tetraspanin markers (CD63, CD81, and CD9). Our preliminary findings show that serum CD81/CD9 exosome abundance is significantly lower in high BMI (&gt;30) subjects, and serum CD63/CD81 exosome abundance may be differentially affected by exercise in subjects with high BMI. Further studies are necessary to define the nucleic acid and protein contents of the exercise‐induced exosomes. To this end, we have generated a transgenic mouse with an inducible skeletal muscle specific exosome surface protein reporter, which will allow definitive tracking of exosomes released from skeletal muscle that are delivered to other organ systems.

Potato Protein Ingestion Increases Muscle Protein Synthesis Rates at Rest and during Recovery from Exercise in Humans.

ABSTRACTIntroductionPlant-derived proteins have received considerable attention as an alternative to animal-based proteins and are now frequently used in both plant-based diets and sports nutrition products. However, little information is available on the anabolic properties of potato-derived protein. This study compares muscle protein synthesis rates after the ingestion of 30 g potato protein versus 30 g milk protein at rest and during recovery from a single bout of resistance exercise in healthy, young males.MethodsIn a randomized, double-blind, parallel-group design, 24 healthy young males (24 ± 4 yr) received primed continuous l-[ring-13C6]-phenylalanine infusions while ingesting 30 g potato-derived protein or 30 g milk protein after a single bout of unilateral resistance exercise. Blood and muscle biopsies were collected for 5 h after protein ingestion to assess postprandial plasma amino acid profiles and mixed muscle protein synthesis rates at rest and during recovery from exercise.ResultsIngestion of both potato and milk protein increased mixed muscle protein synthesis rates when compared with basal postabsorptive values (from 0.020% ± 0.011% to 0.053% ± 0.017%·h−1 and from 0.021% ± 0.014% to 0.050% ± 0.012%·h−1, respectively; P < 0.001), with no differences between treatments (P = 0.54). In the exercised leg, mixed muscle protein synthesis rates increased to 0.069% ± 0.019% and 0.064% ± 0.015%·h−1 after ingesting potato and milk protein, respectively (P < 0.001), with no differences between treatments (P = 0.52). The muscle protein synthetic response was greater in the exercised compared with the resting leg (P < 0.05).ConclusionsIngestion of 30 g potato protein concentrate increases muscle protein synthesis rates at rest and during recovery from exercise in healthy, young males. Muscle protein synthesis rates after the ingestion of 30 g potato protein do not differ from rates observed after ingesting an equivalent amount of milk protein.

The effect of active vs passive recovery and use of compression garments following a single bout of muscle-damaging exercise

BACKGROUND: Some recovery strategies are needed to reduce or eliminate the effect of negative symptoms caused by exercise. OBJECTIVE: The aim of this study was to determine the effect of different types of recovery after single-bout strength exercises on biomarkers of muscle damage, cytokine release and lactate elimination. METHODS: Following familiarization, 10 male volunteers performed four randomized recovery protocols (passive or active recovery with or without compression garments) following a single bout of resistance exercise (squat and deadlift exercises). The blood creatine kinase (CK), lactate dehydrogenase (LDH), interleukine-6 (IL-6), and tumor necrosis factor-alfa (TNF-α) values were measured before and after exercise, and after 24, 48, 72 hours. RESULTS: The CK analysis showed that all protocols significantly increased (p&lt; 0.05) CK activity compared to the pre and 24 h post time points. Interestingly, protocol 3 and 4 significantly decreased (p&lt; 0.05) CK activity compared 24 and 72 h post-exercise. LDH, IL-6, and TNF values did not show significant difference (p&gt; 0.05) at the time points tested. CONCLUSIONS: Active recovery is an effective method for reducing the severity and duration of muscle damage and for accelerating the clearance of blood lactate (BLa) following a single bout of strength training. There is no added benefit of using compression garments.

The Effect of a Single Bout of Resistance Exercise with Blood Flow Restriction on Arterial Stiffness in Older People with Slow Gait Speed: A Pilot Randomized Study.

Purpose: Low-intensity resistance exercise with moderate blood-flow restriction (LIRE-BFR) is a new trending form of exercises worldwide. The purpose of this study was to compare the acute effect of a single bout of traditional resistance exercise (TRE) and LIRE-BFR on arterial stiffness in older people with slow gait speeds. Methods: This was a randomized, controlled clinical study. Seventeen older adults (3 men; 14 women; 82 ± 5 years old) completed a session of TRE (n = 7) or LIRE-BFR (n = 10). At baseline and after 60 min post-exercise, participants were subject to blood pressure measurement, heart rate measurements and a determination of arterial stiffness parameters. Results: There was no significant difference between the TRE and LIRE-BFR group at baseline. Pulse-wave velocity increased in both groups (p < 0.05) post-exercise with no between-group differences. Both exercise modalities did not produce any adverse events. The increase in systolic blood pressure, pulse pressure, augmentation pressure and pulse wave velocity (all p > 0.05) were similar after both TRE and LIRE-BFR. Conclusion: TRE and LIRE-BFR had similar responses regarding hemodynamic parameters and pulse-wave velocity in older people with slow gait speed. Long-term studies should assess the cardiovascular risk and safety of LIRE-BFR training in this population.

The effects of acute resistance exercise among young adults: A randomized controlled trial

Background The effects of a single bout of resistance exercise (RE) on state anxiety and worry symptoms are understudied. Further, how resistance exercise training (RET) changes response to acute RE is unknown.Methods Sixty-two untrained young adults (mean age (y):26.6; RET n = 27, Wait-list (WL): n = 35, 62.9% female) were randomized to an eight-week, ecologically-valid, guidelines-based RET condition, or eight-week WL control condition. Two acute RE trials were nested within the design at week one and eight, to determine RE response, and change in RE response following RET. The RET condition completed a twice-weekly RET intervention. The WL condition completed 30-minute bouts of quiet-rest at week one and eight. Two-condition (RE/quiet-rest) x two-time (pre/post) x two-session (weeks one/eight) RM-ANCOVAs examined differences between acute RE and quiet-rest pre-post and between acute sessions. Sub-analyses were conducted among young adults with analogue-Generalized Anxiety Disorder (AGAD). Primary outcomes were anxiety and worry symptoms.Results Compliance was 99% (Rate of perceived exertion (6–20) = 14±1, Muscle soreness (1–10)=4 ± 2), with no adverse events. There were no significant three-way interactions for anxiety symptoms or worry symptoms (all p ≥ 0.51) among the total sample or AGAD sample. The magnitude of change in outcomes at each session for both samples were small and non-significant (Hedges’ d = -0.26 to 0.23).Limitations Post-condition assessment of primary outcomes was only conducted at a single time point.Conclusion RE did not elicit significant reductions in state anxiety or worry symptoms ten minutes post-RE. RET did not change response to acute RE. Clinicians should encourage RET for maximum anxiolytic benefits.

Impact of a single bout of resistance exercise on serum Klotho in healthy young men.

BackgroundIt has been shown that Klotho protects vascular endothelial function. Given that a single bout of resistance‐exercise‐induced hypertensive stimulus causes endothelial dysfunction, we postulated that acute resistance exercise would reduce serum Klotho levels. In this respect, the reduction in serum Klotho levels would be associated with the response of flow‐mediated dilation (FMD). Therefore, the purpose of this study was to investigate the impact of acute resistance exercise on the Klotho response in serum. In addition, we examined the relationship between the serum Klotho and FMD responses following acute resistance exercise.MethodsTwelve untrained men participated in this study (20.4 ± 0.3 years). Following baseline measurements (blood pressure, blood collection, FMD), subjects performed leg extensions, which consisted of 10 repetitions for five sets at 70% of one‐repetition maximum. After the exercise, measurement of blood pressure, blood collection, and FMD assessment were repeated for 60 min. We analyzed Klotho and endothelin‐1 (ET‐1) concentrations in blood serum.ResultsAs expected, the exercise significantly elevated blood pressure and led to decreased FMD (p < 0.05). However, Klotho concentrations were significantly increased following exercise (p < 0.05). No correlation was observed in Klotho and FMD responses following acute resistance exercise. However, there was a significant positive correlation between Klotho and ET‐1 in response to resistance exercise (p < 0.05).ConclusionIn conclusion, the present study reveals that serum Klotho significantly increased following a single bout of resistance exercise. However, the increase in Klotho may not associate with the acute reduction in endothelial function.

Six weeks of high-intensity interval training enhances contractile activity induced vascular reactivity and skeletal muscle perfusion in older adults

Impairments in muscle microvascular function are associated with the pathogenesis of sarcopenia and cardiovascular disease. High-intensity interval training (HIIT) is an intervention by which a myriad of beneficial skeletal muscle/cardiovascular adaptations have been reported across age, including capillarisation and improved endothelial function. Herein, we hypothesised that HIIT would enhance muscle microvascular blood flow and vascular reactivity to acute contractile activity in older adults, reflecting HIIT-induced vascular remodelling. In a randomised controlled-trial, twenty-five healthy older adults aged 65–85 years (mean BMI 27.0) were randomised to 6-week HIIT or a no-intervention control period of an equal duration. Measures of microvascular responses to a single bout of muscle contractions (i.e. knee extensions) were made in the m. vastus lateralis using contrast-enhanced ultrasound during a continuous intravenous infusion of Sonovue™ contrast agent, before and after the intervention period, with concomitant assessments of cardiorespiratory fitness and resting blood pressure. HIIT led to improvements in anaerobic threshold (13.2 ± 3.4 vs. 15.3 ± 3.8 ml/kg/min, P < 0.001), dynamic exercise capacity (145 ± 60 vs. 159 ± 59 W, P < 0.001) and resting (systolic) blood pressure (142 ± 15 vs. 133 ± 11 mmHg, P < 0.01). Notably, HIIT elicited significant increases in microvascular blood flow responses to acute contractile activity (1.8 ± 0.63 vs. 2.3 ± 0.8 (arbitrary contrast units (AU), P < 0.01)), with no change in any of these parameters observed in the control group. Six weeks HIIT improves skeletal muscle microvascular responsiveness to acute contractile activity in the form of active hyperaemia-induced by a single bout of resistance exercise. These findings likely reflect reports of enhanced large vessel distensibility, improved endothelial function, and muscle capillarisation following HIIT. Moreover, our findings illustrate that HIIT may be effective in mitigating deleterious alterations in muscle microvascular mediated aspects of sarcopenia.

Casein and Whey Protein in the Breast Milk Ratio: Could It Promote Protein Metabolism Enhancement in Physically Active Adults?

Due to the utilization of milk proteins such as whey protein (WP) and casein as sports nutrition ergogenic aids, the present study investigated the effects of the association of WP and casein in a ratio of 80:20, a similar ratio of human breast milk, on blood branched-chain amino acid (BCAA) profiles, markers of protein metabolism and delayed onset muscle soreness (DOMS), after a single bout of resistance exercise. A double-blind, crossover and acute study was carried out with ten men (age 29 ± 8 years; BMI: 25.4 ± 2.9 kg/m2; 77 ± 12 kg; 1.74 ± 0.09 m); each one consumed the following supplements randomly, one per session: WP, CAS (casein), WP/CAS (80% WP/20% CAS), CAS/WP (80% CAS/20% WP) and PLA (placebo). They were also subjected to the following evaluations: the one repetition maximum (1RM) test; resistance training session; blood extraction during each session to determine the BCAA profile; two food records; 3-day evaluation of DOMS (24 h, 48 h and 72 h) and nitrogen balance in each treatment. The intervention resulted in similar nitrogen urinary, creatinine and urea plasma levels and showed a positive nitrogen balance in all the trials. Regarding the BCAAs, the peak occurred at 60 min post-ingestion and remained higher until 120 min for WP, WP/CAS and CAS/WP. The DOMS was significantly lower for WP, WP/CAS and CAS/WP compared to the CAS and PLA treatments. There were no advantages in the association of WP and CAS in the BCAAs profile when compared to WP itself, but it induced a lower DOMS compared to CAS and PLA (Clinical Trial registration number: clinicaltrials.gov, NCT04648384).

498-P: Resistance Exercise Rapidly Alters Citric Acid Cycle and Amino Acid Metabolism in Skeletal Muscle

Muscle glucose metabolism is improved by either aerobic or resistance exercise (RE) training, but the mechanisms leading to improved metabolism for each of these exercise modes are not identical. Much work has been done onimproved oxidative metabolism by aerobic exercise, but far less is known about how RE impacts fuel metabolism. Here, TCA and amino acid metabolites are measured in skeletal muscle after a single bout of RE. Twenty one healthy subjects performed a session of one-legged knee extension RE that consisted of 3 sets of 10 reps at 70% of their 1 rep max. Two muscle biopsies were obtained from the vastus lateralis of each leg. From the RE leg, biopsies were obtained ≤10min post-RE (0hr PEX) and approximately 1hr post-RE (1hr PEX), respectively. From the non-RE leg, biopsies were obtained before and 1hr PEX, respectively. Muscle samples were frozen and stored until mass spectrometry analysis of metabolites was performed. A 2-fold increase in plasma lactate (P&amp;lt;0.05) and a 30-40% increase in muscle glycolytic enzyme activity (P&amp;lt;0.05) at 0hr PEX suggest increased activation of the glycolytic pathway. Also at 0hr PEX, TCA metabolites citrate and isocitrate were increased (P&amp;lt;0.05) compared to the pre-RE biopsy (0.35 and 0.01 mmol/μg, respectively). Further, multiple amino acid metabolites Arg, Asn, Lys, Thr, and Val were increased (P&amp;lt;0.05) in the REmuscle at 0hr PEX. These amino acids can enter the TCA cycle at various steps, indicating increased flux through the TCA cycle immediately after RE. By 1hr PEX, TCA intermediates malate and fumarate were reduced (P&amp;lt;0.05)compared to the non-RE leg (-0.65 and -0.35 mmol/μg, respectively), and multiple amino acid metabolites were also reduced (P&amp;lt;0.05). The decrease in these metabolites at 1hr PEX suggests increased use of metabolites for mitochondrial respiration. These results suggest activation of glycolytic and amino metabolism pathways, contributing to citric acid flux immediately following RE in order to meet energy needs in skeletal muscle. Disclosure M. W. Pataky: None. A. Prabha kumar: None. K. Klaus: None. K. Nair: None. Funding National Institutes of Health (R01AG062859)

Acute Inflammatory Response to a Single Bout of Resistance Exercise with or Without Blood Flow Restriction

Background: The effectiveness of resistance training (RT) with blood flow restriction (BFR) is limited from the health perspective. Objectives: This study aimed to investigate the acute inflammatory response to a single bout of RT with or without BFR. Methods: Twenty-four non-athletic male students were randomly divided into 3 groups (n = 8), including: (1) high intensity (HIRT- 80% of 1-RM: 3 × 10 R), (2) low intensity (40% of 1-RM: 3 × 30 R) with BFR (180 mmHg) (LIRT + BFR) and (3) LIRT. Results: Significant increase for IL1-β (p = 0.001), IL-6 (P = 0.001), TNF-α (P = 0.002), CRP (P = 0.007), ICAM1 (P = 0.016), HCY (P = 0.008) were observed. These responses in the HIRE and LIRT + BFR groups were significantly higher than in the LIRT group respectively (P ≤ 0.05). Conclusions: The LIRT + BFR has similar effects to HIRT and can be used in rehabilitation training. The gradual overload and proper recovery are very important due to the increase in acute inflammatory responses.