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1.
Low-dose fentanyl does not alter muscle sympathetic nerve activity, blood pressure, or tolerance during progressive central hypovolemia.
Huang, M, Watso, JC, Belval, LN, Cimino, FA, Fischer, M, Jarrard, CP, Hendrix, JM, Laborde, CH, Crandall, CG
American journal of physiology. Regulatory, integrative and comparative physiology. 2022;(1):R55-R63
Abstract
Hemorrhage is a leading cause of battlefield and civilian trauma deaths. Several pain medications, including fentanyl, are recommended for use in the prehospital (i.e., field setting) for a hemorrhaging solider. However, it is unknown whether fentanyl impairs arterial blood pressure (BP) regulation, which would compromise hemorrhagic tolerance. Thus, the purpose of this study was to test the hypothesis that an analgesic dose of fentanyl impairs hemorrhagic tolerance in conscious humans. Twenty-eight volunteers (13 females) participated in this double-blinded, randomized, placebo-controlled trial. We conducted a presyncopal limited progressive lower body negative pressure test (LBNP; a validated model to simulate hemorrhage) following intravenous administration of fentanyl (75 µg) or placebo (saline). We quantified tolerance as a cumulative stress index (mmHg·min), which was compared between trials using a paired, two-tailed t test. We also compared muscle sympathetic nerve activity (MSNA; microneurography) and beat-to-beat BP (photoplethysmography) during the LBNP test using a mixed effects model [time (LBNP stage) × trial]. LBNP tolerance was not different between trials (fentanyl: 647 ± 386 vs. placebo: 676 ± 295 mmHg·min, P = 0.61, Cohen's d = 0.08). Increases in MSNA burst frequency (time: P < 0.01, trial: P = 0.29, interaction: P = 0.94) and reductions in mean BP (time: P < 0.01, trial: P = 0.50, interaction: P = 0.16) during LBNP were not different between trials. These data, the first to be obtained in conscious humans, demonstrate that administration of an analgesic dose of fentanyl does not alter MSNA or BP during profound central hypovolemia, nor does it impair tolerance to this simulated hemorrhagic insult.
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2.
Dietary palmitate and oleate differently modulate insulin sensitivity in human skeletal muscle.
Sarabhai, T, Koliaki, C, Mastrototaro, L, Kahl, S, Pesta, D, Apostolopoulou, M, Wolkersdorfer, M, Bönner, AC, Bobrov, P, Markgraf, DF, et al
Diabetologia. 2022;(2):301-314
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Abstract
AIMS/HYPOTHESIS Energy-dense nutrition generally induces insulin resistance, but dietary composition may differently affect glucose metabolism. This study investigated initial effects of monounsaturated vs saturated lipid meals on basal and insulin-stimulated myocellular glucose metabolism and insulin signalling. METHODS In a randomised crossover study, 16 lean metabolically healthy volunteers received single meals containing safflower oil (SAF), palm oil (PAL) or vehicle (VCL). Whole-body glucose metabolism was assessed from glucose disposal (Rd) before and during hyperinsulinaemic-euglycaemic clamps with D-[6,6-2H2]glucose. In serial skeletal muscle biopsies, subcellular lipid metabolites and insulin signalling were measured before and after meals. RESULTS SAF and PAL raised plasma oleate, but only PAL significantly increased plasma palmitate concentrations. SAF and PAL increased myocellular diacylglycerol and activated protein kinase C (PKC) isoform θ (p < 0.05) but only PAL activated PKCɛ. Moreover, PAL led to increased myocellular ceramides along with stimulated PKCζ translocation (p < 0.05 vs SAF). During clamp, SAF and PAL both decreased insulin-stimulated Rd (p < 0.05 vs VCL), but non-oxidative glucose disposal was lower after PAL compared with SAF (p < 0.05). Muscle serine1101-phosphorylation of IRS-1 was increased upon SAF and PAL consumption (p < 0.05), whereas PAL decreased serine473-phosphorylation of Akt more than SAF (p < 0.05). CONCLUSIONS/INTERPRETATION Lipid-induced myocellular insulin resistance is likely more pronounced with palmitate than with oleate and is associated with PKC isoforms activation and inhibitory insulin signalling. TRIAL REGISTRATION ClinicalTrials.gov .NCT01736202. FUNDING German Federal Ministry of Health, Ministry of Culture and Science of the State North Rhine-Westphalia, German Federal Ministry of Education and Research, European Regional Development Fund, German Research Foundation, German Center for Diabetes Research.
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Fasting-Mimicking-Diet does not reduce skeletal muscle function in healthy young adults: a randomized control trial.
Nardon, M, Venturelli, M, Ruzzante, F, Longo, VD, Bertucco, M
European journal of applied physiology. 2022;(3):651-661
Abstract
PURPOSE The aim of this study was to evaluate the short- and long-term effects of the Fasting-Mimicking-Diet (FMD) intervention on neuromuscular parameters of force production in healthy young men. METHODS Twenty-four physically active men completed the study. Participants were randomly assigned to Fasting-Mimicking (FMD) or Normal Diet (ND) and asked to follow three cycles of dietary intervention. Neuromuscular parameters of force production during maximal voluntary isometric contractions (MVCs) with the leg extensors muscles and anthropometrics were measured at baseline (T0), at the end of the first cycle (T1), and 7-10 days after the 3rd cycle of the nutritional intervention (T2). The study was registered on Clinicaltrials.gov (No. NCT04476615). RESULTS There was a significant decrease in body mass at T1 for FMD (- 2.6 kg, ∆ from baseline, on average; p < 0.05) but not in ND (- 0.1 kg;). Neuromuscular parameters of force production, muscle volume, and MVC torque did not change or differ between groups across visits. Results were similar even when parameters were normalized by muscle volume. CONCLUSION The consumption of FMD in a group of young healthy male subjects showed to be feasible, and it did not affect neuromuscular parameters of force production. The results suggest that FMD could be safely adopted by strength athletes without detrimental effects on force and muscle volume. Further research in clinical population at risk of muscle mass loss, such as elderly and obese subjects with sarcopenia, is warranted.
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Acute Whole-Body Vibration Exercise Promotes Favorable Handgrip Neuromuscular Modifications in Rheumatoid Arthritis: A Cross-Over Randomized Clinical.
Coelho-Oliveira, AC, Lacerda, ACR, de Souza, ALC, Santos, LMM, da Fonseca, SF, Dos Santos, JM, Ribeiro, VGC, Leite, HR, Figueiredo, PHS, Fernandes, JSC, et al
BioMed research international. 2021;:9774980
Abstract
OBJECTIVE Rheumatoid arthritis (RA) causes progressive changes in the musculoskeletal system compromising neuromuscular control especially in the hands. Whole-body vibration (WBV) could be an alternative for the rehabilitation in this population. This study investigated the immediate effect of WBV while in the modified push-up position on neural ratio (NR) in a single session during handgrip strength (HS) in women with stable RA. METHODS Twenty-one women with RA (diagnosis of disease: ±8 years, erythrocyte sedimentation rate: ±24.8, age: 54± 11 years, BMI: 28 ± 4 kg·m-2) received three experimental interventions for five minutes in a randomized and balanced cross-over order: (1) control-seated with hands at rest, (2) sham-push-up position with hands on the vibration platform that remained disconnected, and (3) vibration-push-up position with hands on the vibration platform turned on (45 Hz, 2 mm, 159.73 m·s-2). At the baseline and immediately after the three experimental interventions, the HS, the electromyographic records (EMGrms), and range of motion (ROM) of the dominant hand were measured. The NR, i.e., the ratio between EMGrms of the flexor digitorum superficialis (FDS) muscle and HS, was also determined. The lower NR represented the greater neuromuscular efficiency (NE). RESULTS The NR was similar at baseline in the three experimental interventions. Despite the nonsignificance of within-interventions (p = 0.0611) and interaction effect (p = 0.1907), WBV exercise reduced the NR compared with the sham and control (p = 0.0003, F = 8.86, η 2 = 0.85, power = 1.00). CONCLUSION Acute WBV exercise under the hands promotes neuromuscular modifications during the handgrip of women with stable RA. Thus, acute WBV exercise may be used as a preparatory exercise for the rehabilitation of the hands in this population. This trial is registered with trial registration 2.544.850 (ReBEC-RBR-2n932c).
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Rationale and Design for a Higher (Dairy) Protein Weight Loss Intervention That Promotes Muscle Quality and Bone Health in Older Adults with Obesity: A Randomized, Controlled Pilot Study.
Miller, MG, Porter Starr, KN, Rincker, J, Orenduff, MC, McDonald, SR, Pieper, CF, Fruik, AR, Lyles, KW, Bales, CW
Journal of nutrition in gerontology and geriatrics. 2021;(2-3):150-170
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Abstract
In contrast to recommendations for young and middle-aged adults, intentional weight loss among older adults remains controversial and is inconsistently advised. Recent research suggests that a higher protein diet can mitigate loss of lean mass during periods of intentional weight loss among older adults with obesity; however, the effects of intentional weight loss on skeletal muscle and bone are not fully understood. The Dairy in the Diet Yields New Approaches for Muscle Optimization (DDYNAMO) trial is a 6-month, randomized, controlled pilot study assessing the effects of combining regular, generous intakes of high quality protein (30 g/meal; primarily from dairy) with caloric restriction (-500kcal/d) and low-intensity resistance exercise (30 min/3 times per week) on muscle quality, muscle composition, bone mineral density in men and women aged ≥60 years with obesity and mild to moderate functional impairment (Short Physical Performance Battery [SPPB] score ≥4 to ≤10). Participants will be re-assessed at 18 months to evaluate weight maintenance, bone mineral density, physical function, and other secondary measures. ClinicalTrials.gov Identifier: NCT02437643.
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Moderate intensity cycling is better than running on recovery of eccentric exercise-induced muscle damage.
de Azevedo Franke, R, Rodrigues, R, Geremia, JM, Teixeira, BC, Boeno, F, Rabello, R, Baroni, BM, Lima, CS
Physical therapy in sport : official journal of the Association of Chartered Physiotherapists in Sports Medicine. 2021;:65-73
Abstract
OBJECTIVE To compare the effects of moderate intensity running and cycling on markers of exercise-induced muscle damage in men. STUDY DESIGN Randomized controlled trial. SETTING Laboratory. PARTICIPANTS Thirty volunteers were randomized in three groups [running (RG; n = 10), cycling (CG; n = 10) and control (CON; n = 10)] and were evaluated at baseline, post 24, 48 and 72 h of knee extensors' muscle damage protocol. CON performed passive recovery, while RG and CG performed active recovery immediately after the protocol, as well as 24 h and 48 h afterwards. MAIN OUTCOMES (i) maximal voluntary isometric contraction (MVIC); (ii) delayed-onset muscle soreness (DOMS); (iii) plasma creatine kinase (CK) and lactate dehydrogenase (LDH) levels. RESULTS No group-by-time interaction was found in any outcome evaluated (p > 0.05). All groups presented decreases in MVIC and increases in DOMS (p < 0.001), without differences in CK and LDH. Compared with CON, exercise groups presented likely beneficial effects for LDH, while only CG had a likely beneficial effect for DOMS. Lastly, CG presented likely/very likely beneficial effects for MVIC and DOMS compared to RG. CONCLUSION Although the null hypothesis analysis did not find differences, the magnitude-based inference analysis suggested that moderate intensity cycling have likely beneficial effects on knee extensor muscle recovery after eccentric exercise protocol.
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Ursolic acid has no additional effect on muscle strength and mass in active men undergoing a high-protein diet and resistance training: A double-blind and placebo-controlled trial.
Lobo, PCB, Vieira, IP, Pichard, C, Marques, BS, Gentil, P, da Silva, EL, Pimentel, GD
Clinical nutrition (Edinburgh, Scotland). 2021;(2):581-589
Abstract
BACKGROUND Ursolic acid (UA) is thought to have an anabolic effect on muscle mass in humans. This study sought to compare the effects of UA and a placebo on muscle strength and mass in young men undergoing resistance training (RT) and consuming a high-protein diet. METHODS A clinical, double-blind, placebo-controlled trial was conducted for 8 weeks. The Control + RT group (CON n = 12) received 400 mg/d of placebo, and the UA + RT group (UA n = 10) received 400 mg/d of UA. Both groups ingested ~1.6 g/kg of protein and performed the same RT program. Pre- and post-intervention, both groups were evaluated for anthropometric measures, body composition, food intake and muscle strength. RESULTS Food intake remained unchanged throughout the study. Both groups showed significant increases in body weight (CON Δ: 2.12 ± 0.47 kg, p = 0.001 vs. UA Δ: 2.24 ± 0.67 kg, p = 0.009), body mass index (BMI) (CON Δ: 0.69 ± 0.15 kg/m2, p = 0.001 vs. UA Δ: 0.75 ± 0.23, p = 0.011) and thigh circumference (CON Δ: 1.50 ± 0.36, p = 0.002 vs. UA Δ: 2.46 ± 0.50 cm, p = 0.003 vs. UA 1.84 ± 0.82 cm, p = 0.001), with differences between them. There was no difference in the arm, waist and hip circumferences. Both groups showed increases in muscle mass (CON Δ: 1.12 ± 0.26, p = 0.001 vs. UA Δ: 1.08 ± 0.28 kg, p = 0.004), but there was no significant difference between them. Additionally, there were significant increases in the one repetition maximum test in the bench press and in the 10-repetition maximum test in the knee extension (CON Δ: 5.00 ± 2.09, p = 0.036 vs. UA Δ: 7.8 ± 1.87, p = 0.340 and CON Δ: 3.58 ± 1.15, p = 0.010 vs. UA Δ: 1.20 ± 0.72, p = 0.133), respectively, with no difference between them. CONCLUSIONS Ursolic acid had no synergic effect on muscle strength and mass in response to RT in physically active men consuming a high-protein diet. BRAZILIAN CLINICAL TRIALS REGISTRY (REBEC): RBR-76tbqs.
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Concurrent endurance and resistance training enhances muscular adaptations in individuals with metabolic syndrome.
Moreno-Cabañas, A, Ortega, JF, Morales-Palomo, F, Ramirez-Jimenez, M, Alvarez-Jimenez, L, Mora-Rodriguez, R
Scandinavian journal of medicine & science in sports. 2021;(7):1440-1449
Abstract
The purpose of the study was to determine if concurrent training (endurance and resistance in a single session) elicits leg muscular adaptations beyond the ones obtained by endurance training alone in sedentary individuals with metabolic syndrome (MetS). Sixty-six MetS individuals (37% women, age 56 ± 7 years, BMI 32 ± 5 kg m-2 and 3.8 ± 0.8 MetS factors) were randomized to undergo one of the following 16-week isocaloric exercise programs: (i) 4 + 1 bouts of 4 min at 90% of HRMAX of intense aerobic cycling (IAC + IAC group; n = 33), (ii) 4 IAC bouts followed by 3 sets of 12 repetitions of 3 lower-limb free-weight exercises (IAC + RT group; n = 33). We measured the effects of training on maximal cycling power, leg press maximum strength (1RM), countermovement jump height (CMJ), and mean propulsive velocity (MPV) at workloads ranging from 10% to 100% of baseline 1RM leg press. After intervention, MetS components (Z-score) improved similarly in both groups (p = 0.002). Likewise, maximal cycling power during a ramp test improved similarly in both groups (time effect p < 0.001). However, leg press 1RM improved more in IAC + RT than in IAC + IAC (47 ± 5 vs 13 ± 5 kg, respectively, interaction p < 0.001). CMJ only improved with IAC + RT (0.8 ± 0.2 cm, p = 0.001). Leg press MPV at heavy loads (ie, 80%-100% 1RM) improved more with concurrent training (0.12 ± 0.01 vs 0.06 ± 0.02 m s-1 , interaction p = 0.013). In conclusion, in unconditioned MetS individuals, intense aerobic cycling alone improves leg muscle performance. However, substituting 20% of intense aerobic cycling by resistance training further improves 1RM leg press, MPV at high loads, and jumping ability while providing similar improvement in MetS components.
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The effect of β-alanine supplementation on high intensity cycling capacity in normoxia and hypoxia.
Patel, KA, Farias de Oliveira, L, Sale, C, James, RM
Journal of sports sciences. 2021;(11):1295-1301
Abstract
The availability of dietary beta-alanine (BA) is the limiting factor in carnosine synthesis within human muscle due to its low intramuscular concentration and substrate affinity. Carnosine can accept hydrogen ions (H+), making it an important intramuscular buffer against exercise-induced acidosis. Metabolite accumulation rate increases when exercising in hypoxic conditions, thus an increased carnosine concentration could attenuate H+ build-up when exercising in hypoxic conditions. This study examined the effects of BA supplementation on high intensity cycling capacity in normoxia and hypoxia. In a double-blind design, nineteen males were matched into a BA group (n = 10; 6.4 g·d-1) or a placebo group (PLA; n = 9) and supplemented for 28 days, carrying out two pre- and two post-supplementation cycling capacity trials at 110% of powermax, one in normoxia and one in hypoxia (15.5% O2). Hypoxia led to a 9.1% reduction in exercise capacity, but BA supplementation had no significant effect on exercise capacity in normoxia or hypoxia (P > 0.05). Blood lactate accumulation showed a significant trial x time interaction post-supplementation (P = 0.016), although this was not significantly different between groups. BA supplementation did not increase high intensity cycling capacity in normoxia, nor did it improve cycling capacity in hypoxia even though exercise capacity was reduced under hypoxic conditions.
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8 weeks of 2S-Hesperidin supplementation improves muscle mass and reduces fat in amateur competitive cyclists: randomized controlled trial.
Martínez Noguera, FJ, Alcaraz, PE, Carlos Vivas, J, Chung, LH, Marín Cascales, E, Marín Pagán, C
Food & function. 2021;(9):3872-3882
Abstract
2S-Hesperidin is the main flavonoid of orange (Citrus sinensis). Previous researches have pointed its effects in muscle development and fat accumulation reduction, although most of these results have not been assessed in humans. The objective of this study is to evaluate the effect of chronic (8-weeks) intake of 2S-hesperidin on amateur cyclists' body composition. A double-blind, parallel and randomized trial, was carried out with 40 amateur cyclists that were divided in two groups, one taking 2S-hesperidin (500 mg d-1, n = 20) and another taking placebo (500 mg d-1 microcellulose, n = 20) for 8 weeks. Dual-energy X-ray absorptiometry (DXA) and anthropometric measurements were used to assess the effect of both treatments on body composition. In addition, the resting metabolic rate was measured. In comparison to placebo, DXA analysis showed a decrease in percentage body fat (%BF) (-10.4%; p = 0.035) and lower limb fat mass (-10.5%; p = 0.029) in favour of 2S-hesperidin. After evaluation of anthropometric data, a decrease in %BF (-3.7%; p = 0.006), total body fat (-3.0%; p = 0.047), ∑ of 8 skinfolds (-6.1%; p = 0.008) was observed in 2S-hesperidin group, but not in placebo. Additionally, there was an increase in muscle mass percentage (1.0%; p = <0.001) and total muscle mass (1.7%; p = 0.011) after ingestion of 2S-hesperidin, with no changes in placebo. Chronic intake of 2S-hesperidin decreased fat mass in amateur cyclists, evaluated through different body composition measurement methodologies (DXA and anthropometry). In addition, 2S-hesperidin supplementation showed a promoting effect on muscle development.