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1.
Am J Physiol Regul Integr Comp Physiol ; 324(6): R720-R734, 2023 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-36939210

RESUMO

Interval training has been found to lower glucose concentrations and increase insulin sensitivity in males but not in females, which may be due to inherent sex-based differences in metabolism. Twenty-four (12/sex) participants completed a bout of high-intensity interval exercise (HIIE, 10 × 1 min at 90% HRmax) to evaluate whether sex influenced the physiological effects of HIIE on postexercise glycemic control during an oral glucose tolerance test (OGTT). Given that body anthropometrics influence postprandial glucose, data were also expressed as a function of the normalized glucose dose. In addition, we examined whether sex differences in postexercise glycemic control were related to sex differences in muscle metabolism and/or insulin signaling proteins. HIIE increased insulin sensitivity in both sexes as characterized by the Matsuda (P = 0.03, ηp2= 0.20) and HOMA-IR (P = 0.047, ηp2 = 0.17) indices. HIIE also lowered insulin concentration during the OGTT (P = 0.04, ηp2 = 0.18) as compared with control. When normalized for glucose dose relative to lean mass, glucose area under the curve (AUC) was lower in females than in males (P ≤ 0.001, ηp2 = 0.47). TBC1D1 Ser237 phosphorylation increased in males, but not in females, postexercise (P = 0.03, ηp2 = 0.19). There was no difference in total insulin signaling protein content, muscle glycogen utilization, or AMPK activation during exercise between the sexes. These findings indicate that when the glucose dose is normalized for differences in body composition glycemic handling is better in females and that an acute bout of HIIE improves insulin sensitivity equally in healthy males and females.


Assuntos
Treinamento Intervalado de Alta Intensidade , Resistência à Insulina , Humanos , Feminino , Masculino , Fosforilação , Exercício Físico/fisiologia , Resistência à Insulina/fisiologia , Insulina/metabolismo , Glucose/metabolismo , Glicemia/metabolismo , Proteínas Ativadoras de GTPase/metabolismo
2.
Exp Physiol ; 108(4): 636-649, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36754374

RESUMO

NEW FINDINGS: What is the central question of this study? Is the attenuation of the respiratory muscle metaboreflex preserved after detraining? What is the main finding and its importance? Inspiratory muscle training increased respiratory muscle strength and attenuated the respiratory muscle metaboreflex as evident by lower heart rate and blood pressure. After 5 weeks of no inspiratory muscle training (detraining), respiratory muscle strength was still elevated and the metaboreflex was still attenuated. The benefits of inspiratory muscle training persist after cessation of training, and attenuation of the respiratory metaboreflex follows changes in respiratory muscle strength. ABSTRACT: Respiratory muscle training (RMT) improves respiratory muscle (RM) strength and attenuates the RM metaboreflex. However, the time course of muscle function loss after the absence of training or 'detraining' is less known and some evidence suggest the respiratory muscles atrophy faster than other muscles. We sought to determine the RM metaboreflex in response to 5 weeks of RMT and 5 weeks of detraining. An experimental group (2F, 6M; 26 ± 4years) completed 5 weeks of RMT and tibialis anterior (TA) training (each 5 days/week at 50% of maximal inspiratory pressure (MIP) and 50% maximal isometric force, respectively) followed by 5 weeks of no training (detraining) while a control group (1F, 7M; 24 ± 1years) underwent no intervention. Prior to training (PRE), post-training (POST) and post-detraining (DETR), all participants underwent a loaded breathing task (LBT) to failure (60% MIP) while heart rate and mean arterial blood pressure (MAP) were measured. Five weeks of training increased RM (18 ± 9%, P < 0.001) and TA (+34 ± 19%, P < 0.001) strength and both remained elevated after 5 weeks of detraining (MIP-POST vs. MIP-DETR: 154 ± 31 vs. 153 ± 28 cmH2O, respectively, P = 0.853; TA-POST vs. TA-DETR: 86 ± 19 vs. 85 ± 16 N, respectively, P = 0.982). However, the rise in MAP during LBT was attenuated POST (-11 ± 17%, P = 0.003) and DETR (-9 ± 9%, P = 0.007) during the iso-time LBT. The control group had no change in MIP (P = 0.33), TA strength (P = 0.385), or iso-time MAP (P = 0.867) during LBT across all time points. In conclusion, RM and TA have similar temporal strength gains and the attenuation of the respiratory muscle metaboreflex remains after 5 weeks of detraining.


Assuntos
Respiração , Músculos Respiratórios , Humanos , Músculos Respiratórios/fisiologia , Exercícios Respiratórios , Músculos Intercostais , Músculo Esquelético , Força Muscular/fisiologia
3.
Am J Physiol Heart Circ Physiol ; 315(5): H1194-H1199, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30074839

RESUMO

Skeletal muscle is the largest and most important site of capillary-tissue exchange, especially during high-energy demand tasks such as exercise; however, information regarding the role of the microcirculation in maintaining skeletal muscle health is limited. Changes in microcirculatory function, as observed with aging, chronic and cardiovascular diseases, and exercise, likely precede any alterations that arise in larger vessels, although further investigation into these changes is required. One of the main barriers to addressing this knowledge gap is the lack of methodologies for quantifying microvascular function in vivo; the utilization of valid and noninvasive quantification methods would allow the dynamic evaluation of microvascular flow during periods of clinical relevance such as during increased demand for flow (exercise) or decreased demand for flow (disuse). Contrast-enhanced ultrasound (CEUS) is a promising noninvasive technique that has been used for diagnostic medicine and more recently as a complementary research modality to investigate the response of the microcirculation in insulin resistance, diabetes, and aging. To improve the reproducibility of these measurements, our laboratory has optimized the quantification protocol associated with a bolus injection of the contrast agent for research purposes. This brief report outlines the assessment of microvascular flow using the raw time-intensity curve incorporated into gamma variate response modeling. CEUS could be used to compliment any macrovascular assessments to capture a more complete picture of the aging vasculature, and the modified methods presented here provide a template for the general analysis of CEUS within a research setting.


Assuntos
Envelhecimento/fisiologia , Meios de Contraste/administração & dosagem , Exercício Físico/fisiologia , Fluorocarbonos/administração & dosagem , Microcirculação , Microvasos/diagnóstico por imagem , Músculo Quadríceps/irrigação sanguínea , Ultrassonografia/métodos , Fatores Etários , Idoso , Velocidade do Fluxo Sanguíneo , Humanos , Masculino , Microbolhas , Microvasos/fisiologia , Pessoa de Meia-Idade , Modelos Cardiovasculares , Contração Muscular , Valor Preditivo dos Testes , Fluxo Sanguíneo Regional , Reprodutibilidade dos Testes
4.
J Nutr ; 148(11): 1760-1775, 2018 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-30383278

RESUMO

Background: Higher-protein (HP) diets are advocated for several reasons, including mitigation of sarcopenia, but their effects on kidney function are unclear. Objective: This meta-analysis was conducted to determine the effect of HP intakes on kidney function in healthy adults. Methods: We conducted a systematic review and meta-analysis of trials comparing HP (≥1.5 g/kg body weight or ≥20% energy intake or ≥100 g protein/d) with normal- or lower-protein (NLP; ≥5% less energy intake from protein/d compared with HP group) intakes on kidney function. Medline and EMBASE databases were searched. Randomized controlled trials comparing the effects of HP with NLP (>4 d duration) intakes on glomerular filtration rate (GFR) in adults without kidney disease were included. Results: A total of 2144 abstracts were reviewed, with 40 articles selected for full-text review; 28 of these were analyzed and included data from 1358 participants. Data were analyzed using random-effects meta-analysis (RevMan 5; The Cochrane Collaboration), meta-regression (STATA; StataCorp), and dose-response analysis (Prism; GraphPad). Analyses were conducted using postintervention (post) GFR and the change in GFR from preintervention to post. The post-only comparison showed a trivial effect for GFR to be higher after HP intakes [standardized mean difference (SMD): 0.19; 95% CI: 0.07, 0.31; P = 0.002]. The change in GFR did not differ between interventions (SMD: 0.11; 95% CI: -0.05, 0.27; P = 0.16). There was a linear relation between protein intake and GFR in the post-only comparison (r = 0.332, P = 0.03), but not between protein intake and the change in GFR (r = 0.184, P = 0.33). The main limitation of the current analysis is the unclear risk of selection bias of the included trials. Conclusions: Postintervention GFR comparisons indicate that HP diets result in higher GFRs; however, when changes in GFR were compared, dietary protein had no effect. Our analysis indicates that HP intakes do not adversely influence kidney function on GFR in healthy adults.


Assuntos
Dieta com Restrição de Proteínas , Proteínas Alimentares/administração & dosagem , Taxa de Filtração Glomerular/efeitos dos fármacos , Adulto , Humanos
5.
J Nutr ; 148(7): 1088-1095, 2018 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-29901760

RESUMO

Background: Older adults show a blunted muscle protein synthesis (MPS) response to postprandial hyperaminoacidemia relative to younger adults. Evidence suggests that this anabolic resistance can be overcome by consuming greater quantities of leucine. Objective: The purpose of this trial was to determine whether the addition of leucine to a smaller dose (10 g) of milk proteins would, when compared with a larger dose (25 g) of whey protein isolate (WPI), result in similar increases in acute (hourly) and integrated (daily) myofibrillar protein synthesis (myoPS). Methods: Healthy older (mean ± SD age: 69 ± 1 y) women (n = 11/group) were randomly assigned with the use of a single-blind, parallel-group design to twice-daily consumption of either WPI [25 g WPI (3 g l-leucine)] or leucine (LEU; 10 g milk protein with 3 g total l-leucine) for 6 d. Participants performed unilateral resistance exercise to allow assessment of the impact of the supplement alone and with resistance exercise. We determined acute (13C6-phenylanine) and integrated [using deuterated water (D2O)] rates of myoPS in the fasting (acute), basal (integrated), nonexercised, and exercised states. Results: Acute myoPS increased in both legs in response to LEU (fed: 45%; fed+exercise: 71%; P < 0.001) and WPI (fed: 29%; fed+exercise: 47%; P < 0.001) compared with fasting; the increase was greater with LEU than with WPI in the exercised leg (46%; P = 0.04) but not in the rested leg (P = 0.07). The acute myoPS response was greater in the exercised leg than in the rested leg for both WPI (63%) and LEU (58%) (P < 0.001). Integrated myoPS increased with WPI and LEU in the exercised leg (both 9%; P < 0.001) during supplementation, and with WPI (3%; P = 0.02) but not LEU (2%, P = 0.1) in the rested leg compared with the basal state. Conclusions: A lower-protein (10 compared with 25 g/dose), leucine-matched beverage induced similar increases in acute and integrated myoPS in healthy older women. Lower-protein supplements with added leucine may represent an advantageous approach in older adults to maintain skeletal muscle anabolic sensitivity and attenuate muscle loss; however, further work is needed using longer-term interventions to substantiate these findings. This trial was registered at www.clinicaltrials.gov as NCT02282566.


Assuntos
Suplementos Nutricionais/análise , Leucina/farmacologia , Proteínas Musculares/metabolismo , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/metabolismo , Idoso , Proteínas Alimentares/administração & dosagem , Proteínas Alimentares/síntese química , Exercício Físico , Feminino , Humanos , Leucina/administração & dosagem
6.
Br J Sports Med ; 52(6): 376-384, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28698222

RESUMO

OBJECTIVE: We performed a systematic review, meta-analysis and meta-regression to determine if dietary protein supplementation augments resistance exercise training (RET)-induced gains in muscle mass and strength. DATA SOURCES: A systematic search of Medline, Embase, CINAHL and SportDiscus. ELIGIBILITY CRITERIA: Only randomised controlled trials with RET ≥6 weeks in duration and dietary protein supplementation. DESIGN: Random-effects meta-analyses and meta-regressions with four a priori determined covariates. Two-phase break point analysis was used to determine the relationship between total protein intake and changes in fat-free mass (FFM). RESULTS: Data from 49 studies with 1863 participants showed that dietary protein supplementation significantly (all p<0.05) increased changes (means (95% CI)) in: strength-one-repetition-maximum (2.49 kg (0.64, 4.33)), FFM (0.30 kg (0.09, 0.52)) and muscle size-muscle fibre cross-sectional area (CSA; 310 µm2 (51, 570)) and mid-femur CSA (7.2 mm2 (0.20, 14.30)) during periods of prolonged RET. The impact of protein supplementation on gains in FFM was reduced with increasing age (-0.01 kg (-0.02,-0.00), p=0.002) and was more effective in resistance-trained individuals (0.75 kg (0.09, 1.40), p=0.03). Protein supplementation beyond total protein intakes of 1.62 g/kg/day resulted in no further RET-induced gains in FFM. SUMMARY/CONCLUSION: Dietary protein supplementation significantly enhanced changes in muscle strength and size during prolonged RET in healthy adults. Increasing age reduces and training experience increases the efficacy of protein supplementation during RET. With protein supplementation, protein intakes at amounts greater than ~1.6 g/kg/day do not further contribute RET-induced gains in FFM.


Assuntos
Proteínas Alimentares/administração & dosagem , Suplementos Nutricionais , Força Muscular , Músculo Esquelético/fisiologia , Treinamento Resistido , Adulto , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto , Análise de Regressão
7.
Exp Physiol ; 101(2): 243-9, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26459076

RESUMO

NEW FINDINGS: What is the topic of this review? The topic is how sex influences carbohydrate and fat metabolism during exercise and whether this influences adaptation to nutritional and exercise regimens aiming to improve health and performance. What advances does it highlight? Women respond differently to certain nutritional and training regimens aimed at improving health and performance. Few studies have included women in trials and thus we are unsure how women respond to nutritional and training strategies aimed at improving health and performance. Sex-based differences in substrate metabolism during moderate-intensity endurance exercise (END) have been well established. Specifically, during END of the same relative intensity women have a lower respiratory exchange ratio than men, indicative of a lesser reliance on carbohydrate oxidation to support fuel requirements for exercise. In fact, compared with men, women show a lesser reliance on both liver and muscle glycogen during END. Sex-based differences in intramyocellular lipid (IMCL) utilization during END are controversial. However, women have a larger depot of IMCL available to support END fuel needs and a greater percentage of IMCL in contact with mitochondria after a bout of END compared with men, suggestive of a greater capacity to use IMCL. These sex-based differences in metabolism during END are known to be mediated by oestrogen. Despite the well-recognized sexual dimorphisms in substrate metabolism during END, there is a paucity of research examining the effects of exercise and nutritional regimens aimed to enhance performance and/or health in women. Furthermore, the evidence that does exist is suggestive of discordance in the effectiveness of nutritional and exercise regimens between the sexes. The focus of this review is to provide an overview of the well-established sex-based differences in metabolism during END and how they relate to the physiological responses to nutritional and exercise strategies intended to improve exercise performance and/or health.


Assuntos
Exercício Físico/fisiologia , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiologia , Resistência Física/fisiologia , Metabolismo Energético/fisiologia , Feminino , Humanos , Caracteres Sexuais
9.
Med Sci Sports Exerc ; 56(5): 953-962, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38181209

RESUMO

PURPOSE: Sedentary behavior may contribute to increased central wave reflection due to associated peripheral vasoconstriction, yet its impact on central hemodynamics and the mitigating effects of interventional strategies have not been thoroughly investigated. We tested whether standing or seated elliptical breaks alleviate the deleterious effects of prolonged sitting on central wave reflections. METHODS: Eighteen healthy adults (9 9 females, 25 ± 3 yr) completed three 3-h protocols on separate days: uninterrupted sitting, sitting with periodic standing, and sitting with periodic seated elliptical activity. Central wave reflection, central pulse wave velocity, and lower-limb pulse wave velocity were measured before and after each intervention. RESULTS: Central relative wave reflection magnitude (RM) increased during sitting (0.31 ± 0.05 to 0.35 ± 0.05; P < 0.01) but did not change after standing (0.30 ± 0.05 to 0.32 ± 0.04; P = 0.19) or elliptical protocols (0.30 ± 0.05 to 0.30 ± 0.04; P > 0.99). The change in RM during prolonged sitting (ΔRM) was attenuated with elliptical activity (0.04 ± 0.05 vs 0.00 ± 0.03; P = 0.02) but not with periodic standing (0.04 ± 0.04 vs 0.02 ± 0.05; P = 0.54). In addition, augmentation index and central pulse wave velocity increased after sitting (both P < 0.01) and periodic standing (both P < 0.01) but were unchanged after elliptical activity. Lower limb pulse wave velocity did not change after sitting ( P = 0.73) or standing ( P = 0.21) but did decrease after elliptical activity ( P = 0.03). CONCLUSIONS: Prolonged sitting without interruptions increased central wave reflection, whereas elliptical but not standing interruptions were able to ameliorate multiple sitting-induced vascular consequences. More work is required to examine the long-term effectiveness of interruption strategies, as well as the optimal type, frequency, and duration for reducing vascular risk associated with sedentary behaviors.


Assuntos
Análise de Onda de Pulso , Doenças Vasculares , Adulto , Feminino , Humanos , Exercício Físico , Posição Ortostática , Extremidade Inferior
10.
Appl Physiol Nutr Metab ; 49(7): 943-955, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38518263

RESUMO

Exercise has long been known for its beneficial effects on insulin sensitivity (IS) and glucose handling with both moderate-intensity continuous (MIC) exercise and resistance exercise (RE) inducing beneficial effects. In recent years, low-load, high-repetition (LLHR) RE has emerged as a strategy to increase muscle mass and strength to levels similar to traditional RE; however, the effects of LLHR RE on glucose handling has yet to be investigated. The purpose of this trial was to compare the acute effects of LLHR RE to MIC exercise on post-exercise glycemic control and insulin sensitivity in males and females. Twenty-four (n = 12/sex) participants completed acute bouts of MIC exercise (30 min at 65% V̇O2peak) and LLHR (3 circuits, 6 exercises/circuit, 25-35 repetitions/exercise/circuit) matched for time with muscle biopsies immediately pre and post exercise and an oral glucose tolerance test (OGTT) 90 min following exercise. Blood glucose concentrations (p = 0.002, ηp 2 = 0.37), glucose AUC (p = 0.002, ηp 2 = 0.35) and max glucose concentration (p = 0.003, ηp 2 = 0.34) were lower during the post exercise OGTT following LLHR RE compared to MIC exercise. There was a main effect of trial on TBC1D1 Ser237 phosphorylation (p = 0.04, ηp 2 = 0.19) such that it was greater following MIC exercise compared to LLHR RE. Furthermore, phosphorylated ACC Ser79 increased following MIC exercise with no change following LLHR RE (p < 0.001, ηp 2 = 0.50). Phosphorylation of PTEN Ser380 was greater in males than females during LLHR RE (p = 0.01, ηp 2 = 0.27). These findings suggest that LLHR RE is a feasible exercise modality to improve post-exercise glycemic control in both males and females. Trial registration number: NCT06217679.


Assuntos
Glicemia , Controle Glicêmico , Resistência à Insulina , Músculo Esquelético , Treinamento Resistido , Humanos , Feminino , Masculino , Treinamento Resistido/métodos , Glicemia/metabolismo , Resistência à Insulina/fisiologia , Controle Glicêmico/métodos , Adulto Jovem , Adulto , Músculo Esquelético/fisiologia , Músculo Esquelético/metabolismo , Teste de Tolerância a Glucose , Insulina/sangue , Exercício Físico/fisiologia
11.
Phys Ther ; 103(10)2023 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-37669136

RESUMO

OBJECTIVE: The purpose of this trial is to evaluate the effect of twice-weekly, moderate-to-high intensity progressive resistance training (PRT) for 1 year on lumbar spine bone mineral density (BMD) in individuals with low BMD, compared to attention control. Secondary analyses will examine if resistance training improves other health outcomes; if high intensity is more effective than moderate intensity resistance training for all outcomes; the cost of intervention versus benefit; the willingness to pay; and harms. METHODS: For this study, 324 men or postmenopausal women aged ≥50 years with a femoral neck, total hip, or lumbar spine BMD T-score of ≤-1, or a Fracture Risk Assessment Tool probability of ≥20% for major osteoporotic fracture or ≥ 3% for hip fracture are being recruited to participate in a randomized controlled trial with 1:1:1 randomization. Participants will be stratified by site (3 centers) to twice-weekly, supervised PRT at moderate intensity (about 10 repetitions maximum), to high intensity PRT (≤6 repetitions maximum), or to a home posture and balance exercise program (attention control) for 1 year (resistance training to comparator allocation ratio of 2:1). The primary outcome is lumbar spine BMD via dual-energy X-ray absorptiometry. Secondary outcomes include trabecular bone score, proximal femur and total hip BMD and structure, bone-free and appendicular lean mass, physical functioning, falls, fractures, glucose metabolism, cost per life-year gained, adverse events, and quality of life. Between-group differences will be tested in intention-to-treat and per-protocol analyses using analysis of covariance, chi-square tests, or negative binomial or logistic regression, adjusting for site and baseline values. IMPACT: The Finding the Optimal Resistance Training Intensity For Your Bones trial will support decision making on resistance training for people at risk of fracture.

12.
Physiol Rep ; 10(13): e15354, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35785485

RESUMO

Type 2 diabetes (T2D) risk is lower in females than males. It has been reported that females have greater pancreatic 𝛽-cell function than males, which may at least in part contribute to the T2D risk in females. 𝛽-cell function is influenced by exercise training; however, previous trials comparing 𝛽-cell function between the sexes have not included participants matched for training status. Furthermore, the acute effects of different modes of exercise on 𝛽-cell function, and whether sex inherently influences these effects, are largely unexamined. Males and females (12/sex) completed a 120-min oral glucose tolerance test (OGTT) at rest (CON) and following acute bouts of high-intensity interval exercise (HIIE), moderate intensity continuous (MIC) exercise, and low-load high-repetition (LLHR) resistance exercise to assess whether sex inherently influences baseline and/or post-exercise pancreatic function in the absence of pathology. We found no sex differences in basal pancreatic 𝛽-cell function. Females had greater basal insulin clearance following MIC exercise compared to males (p = 0.01) and males tended to have a higher potentiation ratio following HIIE (p = 0.07). Females also had lower glucose sensitivity following MIC exercise compared to HIIE (p = 0.007) and LLHR (p = 0.003). Insulin clearance during the OGTT was greater following HIIE as compared with CON and MIC exercise (p = 0.02). 2-H oral glucose insulin sensitivity was greater following LLHR compared to CON (p = 0.01). Acute bouts of different modes of exercise do not differentially influence 𝛽-cell function but do influence insulin clearance and insulin sensitivity. Therefore, sex and exercise mode interact to differentially influence insulin clearance and glucose sensitivity.


Assuntos
Diabetes Mellitus Tipo 2 , Resistência à Insulina , Glicemia , Exercício Físico/fisiologia , Feminino , Glucose , Humanos , Insulina , Resistência à Insulina/fisiologia , Masculino
13.
Appl Physiol Nutr Metab ; 46(5): 443-451, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33113337

RESUMO

Exercise elicits direct benefits to insulin sensitivity but may also indirectly improve glucose uptake by hemodynamic conditioning of the vasculature. The purpose of this study was to examine the modifying effect of 3 different types of exercise on the vascular response to an oral glucose challenge. Twenty healthy adults (9 women, 11 men; aged 23 ± 3 years) completed a standard oral glucose tolerance test (OGTT) at rest, as well as 1.5 hours after moderate continuous cycling exercise (30 min; 65% peak oxygen consumption), high-intensity interval cycling exercise (10 × 1 min at 90% peak heart rate), and lower-load higher-repetition resistance exercise (25-35 repetitions/set, 3 sets). Brachial and superficial femoral artery blood flow, conductance, and oscillatory shear index were measured throughout the OGTT. Regardless of rested state or exercise preconditioning, the OGTT induced reductions in brachial artery blood flow and conductance (p < 0.001), and transient increases in brachial and superficial femoral artery oscillatory shear index and retrograde blood flow (p < 0.01). Continuous cycling and resistance exercise were followed with a small degree of protection against prolonged periods of oscillatory flow. Our findings imply transient peripheral vasoconstriction and decreased limb blood flow during a standard OGTT, for which prior exercise was unable to prevent in healthy adults. Novelty: We investigated the impact of continuous, interval, and resistance exercise on the hemodynamic response to an OGTT. Our findings suggest decreased upper-limb blood flow during an OGTT is not prevented by prior exercise in healthy adults.


Assuntos
Teste de Tolerância a Glucose , Hemodinâmica , Condicionamento Físico Humano/fisiologia , Ciclismo/fisiologia , Glicemia/metabolismo , Artéria Braquial/fisiologia , Feminino , Artéria Femoral/fisiologia , Treinamento Intervalado de Alta Intensidade , Humanos , Insulina/sangue , Masculino , Óxido Nítrico/sangue , Condicionamento Físico Humano/métodos , Fluxo Sanguíneo Regional , Treinamento Resistido , Extremidade Superior/irrigação sanguínea , Vasoconstrição , Adulto Jovem
14.
J Appl Physiol (1985) ; 130(4): 1247-1258, 2021 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-33630674

RESUMO

Muscle disuse rapidly induces insulin resistance (IR). Despite a relationship between intramyocellular lipid (IMCL) content and IR, during muscle-disuse IR develops before IMCL accumulation, suggesting that IMCL are not related to disuse-induced IR. However, recent studies show that it is not total IMCL content, but IMCL size and location that are related to IR. Changes in these IMCL parameters may occur prior to increases in IMCL content, thus contributing to disuse-induced IR. Omega-3 fatty acids may mitigate the effects of disuse on IR by preventing a decline in insulin signaling proteins. Twenty women (age 22 ± 3 yr) received either 5 g·day-1 omega-3 fatty acid or isoenergetic sunflower oil for 4 wk prior to, throughout 2 wk of single-leg immobilization, and during 2 wk of recovery. Changes in IMCL characteristics and insulin signaling proteins were examined in vastus lateralis samples taken before supplementation and immobilization, and following immobilization and recovery. Omega-3 supplementation had no effect. IMCL area density decreased in the subsarcolemmal region during immobilization and recovery (-19% and -56%, respectively, P = 0.009). IMCL size increased in the central intermyofibrillar region during immobilization (43%, P = 0.007), returning to baseline during recovery. PLIN5 and AKT increased during immobilization (87%, P = 0.002; 30%, P = 0.007, respectively). PLIN 5 remained elevated and AKT increased further (15%) during recovery. IRS1, AS160, and GLUT4 decreased during immobilization (-35%, P = 0.001; -44%, P = 0.03; -56%, P = 0.02, respectively), returning to baseline during recovery. Immobilization alters IMCL storage characteristics while negatively affecting unstimulated insulin signaling protein content in young women.NEW & NOTEWORTHY We report that the subcellular storage location of IMCL is altered by limb immobilization, highlighting the need to evaluate IMCL storage location when assessing the effects of disuse on IMCL content. We also found that AKT content increased during immobilization in our female population, contrary to studies in males finding that AKT decreases during disuse, highlighting that men and women may respond differently to disuse and the necessity to include women in all research.


Assuntos
Resistência à Insulina , Perna (Membro) , Adulto , Feminino , Transportador de Glucose Tipo 4/metabolismo , Humanos , Imobilização/efeitos adversos , Metabolismo dos Lipídeos , Lipídeos , Masculino , Músculo Esquelético/metabolismo , Músculo Quadríceps/metabolismo , Adulto Jovem
15.
Gynecol Oncol ; 114(3): 528-35, 2009 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-19560188

RESUMO

OBJECTIVE: To determine the optimal recommended program for the follow-up of patients who are disease free after completed primary therapy for cervical cancer. METHODS: Systematic search of MEDLINE, EMBASE and the Cochrane Library databases (1980-November 2007). RESULTS: Seventeen retrospective trials were identified. Most studies reported similar intervals for follow-up and ranged from a low of 9 visits to a high of 28 visits over 5 years. Follow-up visits typically occurred once every 3-4 months for the first 2 years, every 6 months for the next 3 years and then annually until year 10. All 17 trials reported that a physical exam was performed at each visit. Vaginal vault cytology was analyzed in 13 trials. Other routine surveillance tests included chest x-ray, ultrasound, CT scans, MRI, intravenous pyelography and tumour markers. Median time to recurrence ranged from 7-36 months after primary treatment. Rates of recurrence ranged from 8-26% with 14-57% of patients recurring in the pelvis, and 15-61% of patients recurring at distant or multiple sites. Of the 8-26% of patients who experienced disease recurrence, the vast majority, 89-99%, had recurred by year 5. Upon recurrence, median survival was 7-17 months. Asymptomatic recurrent disease was detected using physical exam in 29-71%, chest x-ray in 20-47%, CT in 0-34% and vaginal vault cytology in 0-17% of patients, respectively. CONCLUSION: There is modest low quality evidence to inform the most appropriate follow-up strategy for patients with cervical cancer who are clinically disease free after receiving primary treatment. Follow-up visits should include a complete physical examination whereas, frequent vaginal vault cytology does not add significantly to the detection of early disease recurrence. Patients should return to annual population-based screening after 5 years of recurrence-free follow-up.


Assuntos
Neoplasias do Colo do Útero/terapia , Feminino , Seguimentos , Humanos , Estudos Retrospectivos
16.
Phys Med Rehabil Clin N Am ; 20(1): 101-31, viii-ix, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19084766

RESUMO

The relative contribution and source of the fuels used during endurance exercise is dependent on the intensity and the duration of the exercise. Much work has been done to investigate the potential performance-enhancing effect of manipulating training and dietary interventions in athletes, as well as the influence of gender. Studies show that even patients with metabolic myopathies may derive benefits that counter the age-associated loss of muscle mass and strength. This article gives an overview of these different impacts on endurance exercise, concluding with an examination of the metabolic myopathies that impair substrate metabolism in skeletal muscle and result in exercise intolerance.

17.
Front Nutr ; 6: 138, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31555655

RESUMO

The prevalence of pre-diabetes (PD) and type II diabetes (T2D) has risen dramatically in recent years affecting an estimated 422 million adults worldwide. The risk of T2D increases with age, with the sharpest rise in diagnosis occurring after age 40. With age, there is also a progressive decline in muscle mass starting after the age of 30. The decline in muscle mass and function due to aging is termed sarcopenia and immediately precedes the sharp rise in T2D. The purpose of the current review is to discuss the role of protein to attenuate declines in muscle mass and insulin sensitivity to prevent T2D and sarcopenia in aging adults. The current recommended dietary allowance for protein consumption is set at 0.8 g/kg/day and is based on dated studies on young healthy men and may not be sufficient for older adults. Protein consumption upwards of 1.0-1.5 g/kg/day in older adults is able to induce improvements in glycemic control and muscle mass. Obesity, particularly central or visceral obesity is a major risk factor in the development of PD and T2D. However, the tissue composition of weight loss in older adults includes both lean body mass and fat mass and therefore may have adverse metabolic consequences in older adults who are already at a high risk of lean body mass loss. High protein diets have the ability to increase weight loss while preserving lean body mass therefore inducing "high-quality weight loss," which provides favorable metabolic changes in older adults. High protein diets also induce beneficial outcomes on glycemic markers due to satiety, lowered post-prandial glucose response, increased thermogenesis, and the ability to decrease rates of muscle protein breakdown (MPB). The consumption of dairy specific protein consumption has also been shown to improve insulin sensitivity by improving body composition, enhancing insulin release, accelerating fat oxidation, and stimulating rates of muscle protein synthesis (MPS) in older adults. Exercise, specifically resistance training, also works synergistically to attenuate the progression of PD and T2D by further stimulating rates of MPS thereby increasing muscle mass and inducing favorable changes in glycemic control independent of lean body mass increases.

18.
Appl Physiol Nutr Metab ; 44(8): 805-813, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30702924

RESUMO

Women and men store lipid differently within the body with men storing more fat in the android region and women storing more fat in the gynoid region. Fat is predominately stored in adipose tissue as triacylglycerides (TG); however, TG are also stored in other tissues including the liver and skeletal muscle. Excess hepatic TG storage, defined as a TG concentration >5% of liver weight and known as nonalcoholic fatty liver disease (NAFLD), is related to the metabolic syndrome. Similarly, elevated skeletal muscle TG, termed intramyocellular lipids (IMCL), are related to insulin resistance in obesity and type II diabetes. Men store more hepatic TG than women and, unsurprisingly, NAFLD is more prevalent in men than women. Women store more IMCL than men, yet type II diabetes risk is not greater, which is likely due to the manner in which women store TG within muscle. Sex-based differences in TG storage between men and women are underpinned by differences in messenger RNA expression, protein content, and enzyme activities of skeletal muscle and hepatic lipid metabolic pathways. Furthermore, women have a greater reliance on lipid during exercise because of upregulation of lipid oxidative pathways. The purpose of this review is to discuss the role of sex in mediating lipid storage and metabolism within skeletal muscle and the liver at rest and during exercise and its relationship with metabolic disease.


Assuntos
Fígado/metabolismo , Músculo Esquelético/metabolismo , Triglicerídeos/metabolismo , Adulto , Feminino , Humanos , Masculino , Fatores Sexuais
19.
Free Radic Biol Med ; 45(4): 503-11, 2008 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-18502211

RESUMO

Obesity is associated with oxidative stress. Endurance training (ET) in healthy individuals increases antioxidant enzyme activity and decreases oxidative stress, whereas its effects on oxidative status in obese humans have yet to be determined. We investigated the effects of obesity and ET on markers of oxidative stress, antioxidant defense, and inflammation. Obese (n=12) and lean (n=12) women underwent 12 weeks of ET with blood, 24-h urine, and muscle biopsies collected prior to and following training for determination of oxidative stress (urinary 8-hydroxy-2-deoxyguanosine and 8-isoprostanes, muscle protein carbonyls, and 4-hydroxynonenal), antioxidant enzyme protein content (muscle CuZnSOD, MnSOD, and catalase), and inflammation (C-reactive protein, leptin, adiponectin, interleukin-6). Obese women had elevated urinary 8-hydroxy-2-deoxyguanosine (P=0.03), muscle protein carbonyls (P=0.03), and 4-hydroxynonenal (P<0.001); serum C-reactive protein (P=0.01); and plasma leptin (P=0.0001) and interleukin-6 (P=0.03). ET decreased urinary 8-hydroxy-2-deoxyguanosine (P=0.006) and 8-isoprostanes (P=0.02) in all subjects and CuZnSOD protein content (P=0.04) in obese women, in the absence of changes in body weight or composition. ET without weight loss decreases systemic oxidative stress, but not markers of inflammation, in obese women.


Assuntos
Exercício Físico , Inflamação/metabolismo , Músculos/metabolismo , Obesidade/metabolismo , Estresse Oxidativo , Adulto , Biomarcadores/urina , Glicemia/análise , Estudos de Casos e Controles , Feminino , Humanos , Insulina/sangue , Redução de Peso
20.
Med Sci Sports Exerc ; 40(5): 892-902, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-18408608

RESUMO

PURPOSE: This study evaluated whether lowering IMCL stores via 3-d consumption of very-low-fat (LFAT) diet impairs endurance performance relative to a moderate-fat diet (MFAT), and whether such a diet unfavorably alters lipid profiles. METHODS: Twenty-one male and female endurance-trained runners followed a controlled diet and training regimen for 3 d prior to consuming either a LFAT (10% fat) or MFAT (35% fat) isoenergetic diet for another 3 d in random crossover fashion. On day 7, runners followed a glycogen normalization protocol (to equalize glycogen stores) and then underwent performance testing (90-min preload run at 62 +/- 1% VO2max followed by a 10-km time trial) on the morning of day 8. Muscle biopsies obtained from vastus lateralis before and after performance testing were analyzed for IMCL (via electron microscopy) and glycogen content (via enzymatic methodology). RESULTS: Despite approximately 30% lower IMCL (0.220 +/- 0.032% LFAT, 0.316 +/- 0.049% MFAT; P = 0.045) and approximately 22% higher muscle glycogen stores at the start of performance testing (P = 0.10), 10-km performance time was not significantly different following the two diet treatments (43.5 +/- 1.4 min LFAT vs 43.7 +/- 1.2 min MFAT). However, LFAT produced less favorable lipid profiles (P < 0.01) by increasing fasting triglycerides (baseline = 84.9 +/- 8.6; LFAT = 118.7 +/- 10.0 mg.dL(-1)) and the total cholesterol:HDL cholesterol ratio (baseline = 3.42 +/- 0.13:1; LFAT = 3.75 +/- 0.20:1), whereas MFAT lowered triglycerides (baseline = 97.5 +/- 12.2; MFAT = 70.9 +/- 7.1 mg.dL(-1)) and the total cholesterol:HDL cholesterol ratio (baseline = 3.47 +/- 0.18:1; MFAT = 3.33 +/- 0.14:1). CONCLUSION: The results suggest that reducing IMCL via 3-d consumption of a LFAT diet does not impair running performance lasting a little over 2 h (compared with 3-d consumption of a MFAT diet plus 1-d glycogen normalization), but that even short-term consumption of a LFAT diet may unfavorably alter serum lipids, even in healthy, endurance-trained runners.


Assuntos
Dieta com Restrição de Gorduras , Gorduras na Dieta , Metabolismo dos Lipídeos , Músculo Esquelético/metabolismo , Resistência Física/fisiologia , Corrida/fisiologia , Adulto , Análise de Variância , Feminino , Glicogênio/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade
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