RESUMEN
The purpose of the present study was to compare next-morning responses of RMR and appetite to pre-sleep consumption of casein protein (CP) in pre- and postmenopausal women. The study was a randomised, crossover, double-blind, placebo-controlled trial. Seven sedentary premenopausal (age: 19·9 (sd 1·2) years; BMI: 23·1 (sd 2·6) kg/m2) and seven sedentary postmenopausal (age: 56·4 (sd 4·9) years; BMI: 26·3 (sd 3·5) kg/m2) women participated. During visit one, anthropometrics and body composition were measured. Following visit one, subjects consumed either CP (25 g) or placebo (PL) ≥2 h after their last meal and ≤30 min prior to sleep on the night before visits two and three. Visits two and three occurred ≥1 week after visit one and were 48 h apart. During visits two and three, RMR (VO2), RER and appetite were measured via indirect calorimetry and visual analogue scale, respectively. Anthropometrics and body composition were analysed by one-way ANOVA. RMR and measures of appetite were analysed using a 2 × 2 (menopause status × CP/PL) repeated-measures ANOVA. Significance was accepted at P ≤ 0·05. RMR was significantly lower in postmenopausal compared with premenopausal women under both conditions (P = 0·003). When consumed pre-sleep CP did not alter RMR, RER or appetite compared with PL when assessed next morning in pre- and postmenopausal women. These data contribute to growing evidence that pre-sleep consumption of protein is not harmful to next-morning metabolism or appetite. In addition, these data demonstrate that menopause may not alter next-morning RMR, RER or appetite after pre-sleep consumption of CP.
Asunto(s)
Apetito/efectos de los fármacos , Metabolismo Basal/efectos de los fármacos , Caseínas/administración & dosificación , Posmenopausia/metabolismo , Premenopausia/metabolismo , Adolescente , Antropometría , Composición Corporal , Índice de Masa Corporal , Calorimetría Indirecta , Estudios Cruzados , Método Doble Ciego , Femenino , Humanos , Persona de Mediana Edad , Conducta Sedentaria , Sueño , Factores de TiempoRESUMEN
While prognosis for breast cancer in women has improved, adverse side effects of treatments may negatively affect body composition and bone mineral density (BMD). This study assessed body composition and BMD changes in breast cancer survivors (BCS) (n = 10, 57.9 ± 5.7 years) and age-matched women (non-cancer, n = 10, 56.5 ± 4.3 years) over a 12- to 15-month period via dual-energy X-ray absorptiometry. No differences were observed between groups at baseline except forearm BMD values were lower in BCS (BCS: 0.462 ± 0.070 g/cm2 ; Control: 0.539 ± 0.052 g/cm2 , p = .012). Body fat increased in both groups compared to baseline (BCS: 38.3-39.6 kg, p = .013; Control: 38.2-39.5 kg, p = .023) at the follow-up. Significant decreases in BMD at the lumbar spine, femoral neck, total femur and ulna were observed in both groups. Breast cancer survivors had a greater decrease in left femoral neck BMD. While BCS demonstrated lower baseline forearm BMD values and a greater decrease in left femoral neck BMD, both groups showed an increase in body fat and decrease in forearm BMD. These findings support the implementation of interventions to improve body composition and BMD in both BCS and women without cancer.
Asunto(s)
Composición Corporal/fisiología , Densidad Ósea/fisiología , Neoplasias de la Mama/fisiopatología , Supervivientes de Cáncer , Absorciometría de Fotón , Anciano , Estudios de Casos y Controles , Femenino , Estudios de Seguimiento , Humanos , Persona de Mediana Edad , Posmenopausia , Conducta SedentariaRESUMEN
The purpose of the present study was to determine whether resistance training alters the cardiovascular responses to submaximal lower body negative pressure (LBNP) in the elderly. Twenty-one subjects were randomized into a control (C: n=10; 70 +/- 3 years, mean +/- SD) or a resistance training (TR: n=11; 67 +/- 7 years) group. Subjects in the TR underwent 12 weeks of training consisting of three sets of 8-12 contractions at approximately 60-80% of their initial maximal one repetition, three times per week, on 10 different machines. Before (Pre) and after (Post) training, all subjects underwent exposures of LBNP of -10, -20 and -40 Torr and muscle biopsy sampling at the vastus lateralis. TR increased (P< or =0.05) knee extension (Pre=379 +/- 140 N, Post=534 +/- 182 N) and chest press (Pre=349 +/- 137 N, Post=480 +/- 192 N) strength. Neither body weight nor percentage body fat were altered (P >0.05) by training. Resistance training increased (P< or =0.05) cross-sectional area in both Type I (4203 +/- 1196 to 5248 +/- 1728 microm2) and Type II (3375 +/- 1027 to 4286 +/- 1892 microm2) muscle fibres. Forearm blood flow, forearm vascular conductance, mean arterial pressure, and heart-rate responses to LBNP were not altered by the training. These data suggest that the cardiovascular responses of elderly to LBNP are unaffected by 12 weeks of whole-body resistance training despite increases in muscle strength and size.
Asunto(s)
Envejecimiento/fisiología , Fenómenos Fisiológicos Cardiovasculares , Presión Negativa de la Región Corporal Inferior , Levantamiento de Peso , Anciano , Anciano de 80 o más Años , Biopsia , Presión Sanguínea/fisiología , Femenino , Antebrazo/irrigación sanguínea , Frecuencia Cardíaca/fisiología , Humanos , Masculino , Persona de Mediana Edad , Fibras Musculares Esqueléticas/patología , Músculo Esquelético/patología , Músculo Esquelético/fisiología , Flujo Sanguíneo Regional/fisiología , Grosor de los Pliegues CutáneosRESUMEN
The effects of supplementation of the leucine metabolite beta-hydroxy-beta-methylbutyrate (HMB) were examined in a resistance training study. Thirty-nine men and 36 women between the ages of 20-40 y were randomized to either a placebo (P) supplemented or HMB supplemented (3.0 g HMB/d) group in two gender cohorts. All subjects trained three times per week for 4 wk. In the HMB group, plasma creatine phosphokinase levels tended to be suppressed compared to the placebo group following the 4 wk of resistance training (HMB:174. 4 +/- 26.8 to 173.5 +/- 17.0 U/L; P:155.0 +/- 20.8 to 195.2 +/- 23.5 U/L). There were no significant differences in strength gains based on prior training status or gender with HMB supplementation. The HMB group had a greater increase in upper body strength than the placebo group (HMB:7.5 +/- 0.6 kg; P:5.2 +/- 0.6 kg; P = 0.008). The HMB groups increased fat-free weight by 1.4 +/- 0.2 kg and decreased percent fat by 1.1% +/- 0.2% while the placebo groups increased fat-free weight by 0.9 +/- 0.2 kg and decreased percent fat by 0.5% +/- 0.2% (fat-free weight P = 0.08, percent fat P = 0.08, HMB compared to placebo). In summary, this is the first short-term study to investigate the roles of gender and training status on the effects of HMB supplementation on strength and body composition. This study showed, regardless of gender or training status, HMB may increase upper body strength and minimize muscle damage when combined with an exercise program.
Asunto(s)
Suplementos Dietéticos , Ejercicio Físico , Valeratos/administración & dosificación , Tejido Adiposo , Adulto , Composición Corporal , Estudios de Cohortes , Creatina Quinasa/sangre , Método Doble Ciego , Femenino , Humanos , Masculino , Placebos , Caracteres Sexuales , Levantamiento de PesoRESUMEN
BACKGROUND: The purpose of this study was to examine the relationships among relative maximal heart rate (%HRmax), maximal heart rate reserve (%HRmax reserve), and maximal oxygen uptake (%VO2max) during submaximal exercise by elderly subjects. METHODS: VO2max and HRmax were determined on 36 women and 19 men, 60 to 80 yrs of age, by a maximal treadmill test to volitional exhaustion. On a separate day, subjects underwent a submaximal treadmill protocol consisting of three 6-min exercise stages at treadmill speeds and grades estimated to elicit 40%, 60%, and 80% of HRmax reserve. Cardiorespiratory responses were determined during mins 4-5 and 5-6 of each stage. RESULTS: Measured exercise intensities expressed by the three methods were: %HRmax reserve = 36, 55, and 79%; %HRmax = 65, 75, and 88%; %VO2max = 53, 69, and 88%. %HRmax was greater (p < .05) than %VO2max at 53 and 69% of VO2max. %HRmax reserve was less (p < .05) than %VO2max for all three intensities. Slopes and intercepts for the linear regression equations relating %VO2max with %HRmax and with %HRmax reserve differed between men and women (p < .05). The regression equation relating %VO2max and %HRmax was y = -22.8 + 1.2 (%HRmax) -13.0 (Gender) + 0.2 (%HRmax x Gender): standard error of the estimate (SEE) = 9.7% and R2 = .71. The regression equation relating %VO2max and %HRmax reserve was y = 32.4 + 0.7 (%HRmax reserve) -10.9 (Gender) + 0.2 (%HRmax reserve x Gender): SEE = 9.8% and R2 = .70 (Gender: F = 0; M = 1). CONCLUSIONS: The data indicate that there is considerable variability among methods of expressing exercise intensity and that %HRmax more closely represents %VO2max than does %HRmax reserve (p < .05) in older adults. These results are in contrast to what has been shown with younger subjects and with American College of Sports Medicine guidelines for exercise prescription.
Asunto(s)
Frecuencia Cardíaca/fisiología , Consumo de Oxígeno/fisiología , Esfuerzo Físico/fisiología , Anciano , Anciano de 80 o más Años , Envejecimiento , Presión Sanguínea/fisiología , Prueba de Esfuerzo , Tolerancia al Ejercicio , Femenino , Corazón/fisiología , Humanos , Modelos Lineales , Pulmón/fisiología , Masculino , Persona de Mediana Edad , Percepción , Intercambio Gaseoso Pulmonar/fisiología , Factores SexualesRESUMEN
The effects of exercise training on the pharmacokinetics of orally administered propranolol were studied in young and elderly healthy volunteers. Twenty-three young (30 +/- 5 years of age) and 20 elderly (67 +/- 5 years of age) adults were randomly assigned to endurance training (N = 12 young subjects, 10 elderly subjects) or nonexercising control (N = 11 young subjects, 10 elderly subjects) groups. Training consisted of treadmill walking, stair climbing, or both three times per week for 40 minutes at 70-85% of maximal heart rate reserve for 16 weeks. Resting plasma propranolol concentrations after a single dose of 80 mg of oral propranolol were measured by high performance liquid chromatography with fluorescence detection, and estimated hepatic blood flow measured was measured using indocyanine green during supine test. Aerobic training increased maximal oxygen uptake (VO2 max) by 13% and 14% in the exercising young and elderly groups, respectively. There was no change in VO2 max in either control group. Adjusted mean estimated hepatic blood flow after exercise corrected for body weight for the young subjects who did not exercise (15.6 mL/min/Kg) and those who did (18.2 mL/min/Kg) groups were of borderline significance. No statistical differences were detected in the experimental propranolol pharmacokinetic parameters (maximal concentration, time of maximal concentration, terminal half-life, area under the curve, and protein binding) or derived pharmacokinetic parameters (intrinsic clearance, bioavailability, clearance, and volume of distribution). These results provide evidence that changes in aerobic fitness do not produce corresponding changes in propranolol pharmacokinetics in young or elderly adults.
Asunto(s)
Antagonistas Adrenérgicos beta/farmacocinética , Envejecimiento/metabolismo , Ejercicio Físico/fisiología , Propranolol/farmacocinética , Administración Oral , Antagonistas Adrenérgicos beta/sangre , Adulto , Anciano , Anciano de 80 o más Años , Cromatografía Líquida de Alta Presión , Esquema de Medicación , Femenino , Humanos , Masculino , Persona de Mediana Edad , Propranolol/sangreRESUMEN
To evaluate the effect of aerobic and variable resistance exercise training on fractionated reaction time (RT) and speed of movement (SM) in elderly individuals, premotor time (PMT), motor time (MT), total RT, and SM were measured in 49 healthy, untrained men and women, 70 to 79 years of age, before and after 6 months of training. Subjects were randomized into either a walk/jog (n = 17), a strength training (n = 20), or a control group (n = 12). Improvements in aerobic capacity were only weakly related to reduced total RT (r = 0.30, p less than .05). Analysis of covariance revealed that there were no differences (p greater than .05) among the three groups after training with respect to PMT, MT, total RT, and SM. These findings indicate that 6 months of aerobic and strength training did not induce significant changes in RT or SM in this group.