Energy cost of single-set resistance training in older adults

The purpose of this study was (a) to assess the intensity and energy cost of a single-set resistance training (RT) protocol as recommended by the recent American College of Sports Medicine (ACSM) guidelines for older adults and (b) to compare obtained values to those recently reported as eliciting health benefits via endurance-based physical activity (PA). Five males and 5 females (73.1 +/- 5.5 years) performed 1 set of 15 repetitions of 8 RT exercises while connected to a portable metabolic unit (CosMed K4b2). The RT intensity (metabolic equivalents [METs]) was 3.3 +/- 0.7 (males) and 3.0 +/- 0.6 (females). Energy cost (kcal) was 84.2 +/- 14.6 (males) and 69.7 +/- 17.4 (females). We conclude that a single-set 8-exercise RT protocol may be a feasible alternative for achieving moderate intensity (3-6 METs) for older adults but that additional sets and/or repetitions appear to be necessary to accumulate moderate amounts (150-200 kcal) of PA.     

Physiological adaptation in noncompetitive rock climbers: good for aerobic fitness?

The present investigation aimed to establish whether noncompetitive rock climbing fulfills sports medicine recommendations for maintaining a good level of aerobic fitness. The physiological profile of 13 rock climbers, 8 men (age, 43 +/- 8 years) and 5 women (age, 31 +/- 8 years) was assessed by means of laboratory tests. Maximal aerobic power (VO2peak) and ventilatory threshold (VT) were assessed using a cycloergometer incremental test. During outdoor rock face climbing, VO2 and heart rate (HR) were measured with a portable metabolimeter and the relative steady-state values (VO2 and HR during rock climbing) were computed. Blood lactate was measured during recovery. All data are presented as mean +/- SD. VO2 was 39.1 +/- 4.3 mL.kg.min in men and 39.7 +/- 5 mL.kg.min in women, while VT was 29.4 +/- 3.0 mL.kg.min in men and 28.8 +/- 4.6 mL.kg.min in women. The VO2 during rock climbing was 28.3 +/- 1.5 mL.kg.min in men and 27.5 +/- 3.7 mL.kg.min in women. The HR during rock climbing was 144 +/- 16 b.min in men and 164 +/- 13 b.min in women. The aerobic profile was classified from excellent to superior in accordance with the standards of the American College of Sports Medicine (ACSM). The exercise intensity (VO2 during rock climbing expressed as a percentage of VO2peak) was 70 +/- 6% in men and 72 +/- 8% in women. Moreover, the energy expenditure was 1000-1500 kcal per week. In conclusion, noncompetitive rock climbing has proved to be a typical aerobic activity. The intensity of exercise is comparable to that recommended by the American College of Sports Medicine to maintain good cardiorespiratory fitness.     

Assessment of physical activity in older individuals: a doubly labeled water study.

We compared the accuracy of two physical activity recall questionnaires and a motion detector in 45- to 84-yr-old women (n = 35) and men (n = 32), using doubly labeled water (DLW) in conjunction with indirect calorimetry as the criterion measure. Subjects were administered the Yale Physical Activity Survey (YPAS) and Minnesota Leisure Time Physical Activity Questionnaire (LTA). Physical activity energy expenditure was determined over a 10-day period by using a Caltrac uniaxial accelerometer and DLW in conjunction with indirect calorimetry. In older women, Minnesota LTA (386 +/- 228 kcal/day) and Caltrac (379 +/- 162 kcal/day) underestimated physical activity by approximately 55% compared with DLW (873 +/- 244 kcal/day). No difference was observed between daily physical activity measured by the YPAS (863 +/- 447 kcal/day) and DLW in older women. In older men, Minnesota LTA (459 +/- 288 kcal/day) and Caltrac (554 +/- 242 kcal/day) underestimated daily physical activity by approximately 50-60% compared with DLW (1,211 +/- 429 kcal/day). No difference was found between physical activity measured by the YPAS (1,107 +/- 612 kcal/day) and DLW in older men. Despite no difference in mean physical activity levels between YPAS and DLW in women and men, Bland and Altman (Lancet 1: 307-310, 1986) analyses demonstrated poor concordance between DLW and YPAS (i.e., limits of agreement = -1,310-1,518 kcal/day). Our data suggest that the Minnesota LTA recall and Caltrac uniaxial accelerometer may significantly underestimate free-living daily physical activity energy expenditure in older women and men. Although the YPAS compares favorably with DLW on a group basis, its use as a proxy measure of individual daily physical activity energy expenditure may be limited in older women and men.     

Sex and limb-specific ischemic reperfusion and vascular reactivity

With little known regarding sex and limb heterogeneity, we investigated vascular reactivity and ischemic reperfusion (IR) in the upper and lower extremities of 15 healthy men (26 +/- 2 yr) and women (23 +/- 1 yr). Doppler ultrasound was used to evaluate IR and flow-mediated dilation (FMD) after suprasystolic cuff occlusion in both the arm [brachial artery (BA)] and the leg [popliteal artery (PA)]. Cumulative IR [area under the curve (AUC)], normalized for muscle mass, revealed no sex-related differences in either limb (forearm: men 38 +/- 3 and women 44 +/- 4 ml/100 g; lower leg: men 12 +/- 2 and women 14 +/- 2 ml/100 g), while both groups revealed a greater IR per unit of arm muscle mass (AUC) compared with the lower leg (P < 0.05). The BA and PA were smaller in women (BA 0.31 +/- 0.1, PA 0.47 +/- 0.1 cm) than in men (BA 0.41 +/- 0.1, PA 0.6 +/- 0.2 cm). Absolute FMD/shear rate revealed attenuated vascular function in the PA of the women [women 3.3 +/- 0.6, men 5.0 +/- 0.8 (all x10(-6)) cm/s(-1).s] and no sex difference in the BA [women 1.2 +/- 0.2, men 1.6 +/- 0.1 (all x10(-6)) cm/s(-1).s]. In both sexes the PA demonstrated greater vascular reactivity than the BA. Thus vascular reactivity in healthy young people is greater in the legs, regardless of sex, and women have vascular function similar to men in the upper extremities but appear to have poorer vascular function normalized for shear rate in the lower extremities.     

Energy Expenditure during Sexual Activity in Young Healthy Couples

Objective

To determine energy expenditure in kilocalories (kcal) during sexual activity in young healthy couples in their natural environment and compare it to a session of endurance exercise.

Methods

The study population consisted of twenty one heterosexual couples (age: 22.6 ± 2.8 years old) from the Montreal region. Free living energy expenditure during sexual activity and the endurance exercise was measured using the portable mini SenseWear armband. Perceived energy expenditure, perception of effort, fatigue and pleasure were also assessed after sexual activity. All participants completed a 30 min endurance exercise session on a treadmill at a moderate intensity.

Results

Mean energy expenditure during sexual activity was 101 kCal or 4.2 kCal/min in men and 69.1 kCal or 3.1 kCal/min in women. In addition, mean intensity was 6.0 METS in men and 5.6 METS in women, which represents a moderate intensity. Moreover, the energy expenditure and intensity during the 30 min exercise session in men was 276 kCal or 9.2 kCal/min and 8.5 METS, respectively and in women 213 kCal or 7.1 kCal/min and 8.4 METS, respectively. Interestingly, the highest range value achieved by men for absolute energy expenditure can potentially be higher than that of the mean energy expenditure of the 30 min exercise session (i.e. 306.1 vs. 276 kCal, respectively) whereas this was not observed in women. Finally, perceived energy expenditure during sexual activity was similar in men (100 kCal) and in women (76.2 kCal) when compared to measured energy expenditure.

Conclusion

The present study indicates that energy expenditure during sexual activity appears to be approximately 85 kCal or 3.6 kCal/min and seems to be performed at a moderate intensity (5.8 METS) in young healthy men and women. These results suggest that sexual activity may potentially be considered, at times, as a significant exercise.     

Six months of supervised high-intensity low-volume resistance training improves strength independent of changes in muscle mass in young overweight men

To determine the effects of a 6-month supervised low-volume resistance training (RT) program (1 set, 85-90%, one repetition maximum, 1RM, 3 d x wk(-1)) on muscular strength (1RM) and skeletal muscle mass (SMM) in previously sedentary, overweight men on an ad libitum diet. Nineteen men were randomly assigned to a control (CON, n = 8) or RT (n = 11) group. The exercise protocol consisted of 5 upper- and 4 lower-body exercises using weight machines. CON maintained their sedentary lifestyle. One RM for upper body (chest press [CP] + lat pull-down [LPD]) and lower body (leg press [LP]) and SMM were assessed at baseline, and at 3 and 6 months. Adherence was 96 +/- 2% with an average time to complete each exercise session of 15 +/- 2 minutes. Volume completed per exercise session significantly increased from baseline (2,812 +/- 670 kg) to 6 months (6,411 +/- 2,128 kg). There was a group by time interaction in 1RM for CP, LPD, and LP. Upper-body strength increased significantly (p < 0.001) (31.3 +/- 9.3%) from baseline to 3 months and from 3 to 6 months (17.9 +/- 8.7%). Lower-body strength also increased significantly from baseline to 3 months (17.8 +/- 16.6%) and from 3 to 6 months (32.0 +/- 33.7%). No changes in upper- or lower-body strength occurred in the CON group. There was no group by time interaction for SMM (CON, 34.5 +/- 2.9 kg vs. RT, 34.2 +/- 2.9 kg; p > 0.05) or for energy intake (p > 0.05). In conclusion, a single set resistance training program at 85% of 1RM, 3 d x wk(-1) resulted in continued increases in muscular strength and a very high adherence rate over a 6-month period in sedentary, overweight men independent of significant changes in SMM. This training protocol may increase adherence and produce long-term increases in muscular fitness as part of an adult fitness program.     

Effects of single- vs. multiple-set resistance training on maximum strength and body composition in trained postmenopausal women

The purpose of this study was to examine the effect of a single- vs. a multiple-set resistance training protocol in well-trained early postmenopausal women. Subjects (N = 71) were randomly assigned to begin either with 12 weeks of the single-set or 12 weeks of the multiple-set protocol. After another 5 weeks of regenerational resistance training, the subgroup performing the single-set protocol during the first 12 weeks crossed over to the 12-week multiple-set protocol and vice versa. Neither exercise type nor exercise intensity, degree of fatigue, rest periods, speed of movement, training sessions per week, compliance and attendance, or periodization strategy differed between exercise protocols. Body mass, body composition, and 1 repetition maximum (1RM) values for leg press, bench press, rowing, and leg adduction were measured at baseline and after each period. Multiple-set training resulted in significant increases (3.5-5.5%) for all 4 strength measurements, whereas single-set training resulted in significant decreases (-1.1 to -2.0%). Body mass and body composition did not change during the study. The results show that, in pretrained subjects, multiple-set protocols are superior to single-set protocols in increasing maximum strength.     

Progressive resistance training without volume increases does not alter arterial stiffness and aortic wave reflection

Endurance exercise is efficacious in reducing arterial stiffness. However, the effect of resistance training (RT) on arterial stiffening is controversial. High-intensity, high-volume RT has been shown to increase arterial stiffness in young adults. We tested the hypothesis that an RT protocol consisting of progressively higher intensity without concurrent increases in training volume would not elicit increases in either central or peripheral arterial stiffness or alter aortic pressure wave reflection in young men and women. The RT group (n = 24; 21 +/- 1 years) performed two sets of 8-12 repetitions to volitional fatigue on seven exercise machines on 3 days/week for 12 weeks, whereas the control group (n = 18; 22 +/- 1 years) did not perform RT. Central and peripheral arterial pulse wave velocity (PWV), aortic pressure wave reflection (augmentation index; AIx), brachial flow-mediated dilation (FMD), and plasma levels of nitrate/nitrite (NOx) and norepinephrine (NE) were measured before and after RT. RT increased the one-repetition maximum for the chest press and the leg extension (P < 0.001). RT also increased lean body mass (P < 0.01) and reduced body fat (%; P < 0.01). However, RT did not affect carotid-radial, carotid-femoral, and femoral-distal PWV (8.4 +/- 0.2 vs. 8.0 +/- 0.2 m/sec; 6.5 +/- 0.1 vs. 6.3 +/- 0.2 m/sec; 9.5 +/- 0.3 vs. 9.5 +/- 0.3 m/sec, respectively) or AIx (2.5% +/- 2.3% vs. 4.8% +/- 1.8 %, respectively). Additionally, no changes were observed in brachial FMD, NOx, NE, or blood pressures. These results suggest that an RT protocol consisting of progressively higher intensity without concurrent increases in training volume does not increase central or peripheral arterial stiffness or alter aortic pressure wave characteristics in young subjects.     

The accuracy of the American College of Sports Medicine metabolic equation for walking at altitude and higher-grade conditions

The purpose of this study was to examine the accuracy of the American College of Sports Medicine (ACSM) walking equation at low walking speeds, altitude (1,550 m), and higher grades. Twenty men and women (mean +/- SD, age, 28 +/- 6 years; height, 171 +/- 13 cm; weight, 67.8 +/- 18.1 kg) completed 2 randomized testing sessions under altitude (AL) (P(I)o(2) = 123.1 mm Hg [20.93%]) and sea level control (SLC) (P(I)o(2) = 147.3 mm Hg [25.00%]) conditions. Steady-state oxygen uptake (Vo(2)) was measured while subjects walked at 50 m.min(-1) at 8 separate grades (0, 5, 10, 15, 18, 21, 24, and 27%). Steady-state Vo(2) measurements from the last 2 minutes of each grade in AL and SLC were compared to the predicted Vo(2) of each grade according to the ACSM walking equation. Mean Vo(2) differences between predicted and AL values ranged from -0.5 to 1.4 ml.kg(-1).min(-1), averaged -0.1 ml.kg(-1).min(-1) across all grades, and were significant (p < 0.05) at 0 percent grade. Mean Vo(2) differences between predicted and SLC values ranged from 0.6 to 3.0 ml.kg(-1).min(-1), averaged 1.4 ml.kg(-1).min(-1) across all grades, and were statistically significant (p < 0.05) at 0 and 5 percent. The standard error of the estimate (SEE) for the prediction of Vo(2) under AL and SLC were 2.2 and 2.0 ml.kg(-1).min(-1), respectively. Total errors for the prediction of Vo(2)max under AL and SLC were 2.3 and 2.6 ml.kg(-1).min(-1), respectively. Overall, the findings indicate that the current ACSM prediction equation for walking is appropriate for application at low speeds, moderate altitude, and higher grades.     

Comparison of metabolic and heart rate responses to super slow vs. traditional resistance training

In order to compare the cardiovascular and energy expenditure demands of "Super Slow" (SST) and traditional (TT) resistance training 7 resistance-trained young men (24.3 +/- 3.8 years) had energy expenditure (using indirect calorimetry) and heart rate evaluated during and for 15 minutes after a workout on separate days. Blood lactate levels were also evaluated before and after each intervention. Resting energy expenditure was evaluated in a fasted state using a ventilated canopy prior to any exercise stimulus and 21 to 22 hours after the SST and TT. VO(2) and average heart rate were both significantly higher during the TT than during the SST. The net VO(2) was also significantly higher during the 15 minutes recovery; however, average heart rate was not significantly different between the 2 groups. Total net energy expenditure from oxidative processes was 45% higher for the TT intervention (TT = 155 +/- 28 kcal, and SST = 107 +/- 20 kcal). The significant postexercise lactate difference was almost 2 times greater following the TT than after the SST (TT = 7.9 +/- 1.7 mmol.L(-1).min(-1), and SST = 4.0 +/- 2.0 mmol.L(-1).min(-1)). Finally, adding the estimated energy expenditure of the blood lactate to the net energy expenditure from the VO(2) produced a significant difference that is over 48% greater for the TT intervention (TT = 172 +/- 29 kcal.min(-1), and SST = 116 +/- 22 kcal.min(-1)). No significant repeated measures analysis main effect was found for either resting energy expenditure or respiratory exchange ratio. The metabolic and cardiovascular stimuli were low with SST. Traditional resistance training increases energy expenditure more than SST does and thus may be more beneficial for body weight control.     

Endurance exercise results in DNA damage as detected by the comet assay

To determine if 6 weeks of supplementation with antioxidants could alleviate exercise-induced DNA damage, we studied 21 runners during a 50 km ultramarathon. Subjects were randomly assigned to one of two groups: (1) placebos (PL) or (2) antioxidants (AO) (1000 mg vitamin C and 400 IU RRR-alpha-tocopheryl acetate). The comet assay was used to assess DNA damage in circulating leukocytes at selected time points: pre-, mid-, and 2 h postrace and daily for 6 days postrace. All subjects completed the race: run time 7.1 +/- 0.1 h, energy expenditure 5008 +/- 80 kcal for women (n = 10) and 6932 +/- 206 kcal for men (n = 11). Overall, the percentage DNA damage increased at midrace (p <.02), but returned to baseline by 2 h postrace, indicating that the exercise bout induced nonpersistent DNA damage. There was a gender x treatment x time interaction (p <.01). One day postrace, women taking AO had 62% less DNA damage than women taking PL (p <.0008). In contrast, there were no statistically significant differences between the two treatment groups of men at any time point. Thus, endurance exercise resulted in DNA damage as shown by the comet assay and AO seemed to enhance recovery in women but not in men.     

Physical Activity and Low-Fat Diet: Is it Enough to Maintain Weight Stability in the Reduced-Obese Individual Following Weight Loss by Drug Therapy and Energy Restriction?

DOUCET, ERIC, PASCAL IMBEAULT, NATALIE ALMÉRAS, AND ANGELO TREMBLAY. Physical activity and low-fat diet: Is it enough to maintain weight stability in the reduced-obese individual following weight loss by drug therapy and energy restriction? Obes Res. Objective: The anthropometric and physiological effects of a physical activity (PA) and a mildly energy-restricted low-fat diet (LFD) follow-up program after a long-term dietary restriction were studied in 12 men and 8 women. Research Methods and Procedures: The dietary restriction (?700 kcal/day) was accompanied by a fenfluramine (60 mg/day) or placebo treatment for 15 weeks, whereas the mean duration of the PA-LFD follow-up was 18 weeks. Results: The long-term dietary restriction reduced body weight (?11. 9 and ?7. 6 kg, p<. 001), fat mass (FM) (?10. 6 and ?5. 8 kg, p<0. 01), resting metabolic rate (RMR) (?304 kcal/day, p<0. 01 and ?148 kcal/day, NS) in men and women, respectively. A decrease in fat-free mass (FFM) was also observed in women (?1. 8 kg, p<0. 05). The PA-LFD follow-up preserved weight stability at a reduced body weight and caused an additional significant decrease in FM for men (?3. 4 kg, p<0. 05). This part of the intervention also caused an increase in daily RMR for men (134 kcal/day, NS) to the point where this value no longer differed from the pre-energy restriction value. In contrast, RMR was further reduced in women (?200 kcal/day) to the point where it Significantly differed from initial values (p<0. 01). Resting seated heart rate was reduced by the PA-LFD follow-up in men leading it to differ significantly from both pre- and post-energy restriction values (?8. 5 and ?5. 5 bpm, p<0. 01). Discussion: In conclusion, these results suggest that a PA-LFD follow-up has the potential to permit body weight stability and may even accentuate fat loss in the reduced-obese state. Moreover, resting energy expenditure is increased under such conditions in men. These stimulating effects seem to be specific to energy metabolism since seated heart rate was either further reduced or remained stable in response to the PA-LFD follow-up.     

Energy expenditure of elite female runners measured by respiratory chamber and doubly labeled water.

To determine whether female athletes have unusually low energy requirements as suggested by many food intake studies, energy expenditure (EE) and intake were assessed in nine elite distance runners [26 +/- 3 (SD) yr, 53 +/- 4 kg, 12 +/- 3% body fat, and 66 +/- 4 ml.kg-1.min-1 maximal O2 uptake]. Subjects were admitted to a metabolic ward for 40 h during which 24-h sedentary EE was measured in a respiratory chamber. Free-living EE was then assessed by the doubly labeled water method for the next 6 days while the women recorded all food intake, daily body weight, and training mileage (10 +/- 3 miles/day). Energy intakes estimated from free-living EE (2,826 +/- 312 kcal/day) and body weight changes (-84 +/- 71 g/day) averaged 221 +/- 550 kcal/day in excess of those calculated from food records (2,193 +/- 466 kcal/day). The energy cost of training (1,087 +/- 244 kcal/day) was calculated as the difference between free-living EE and 24-h EE in the respiratory chamber (1,681 +/- 84 kcal/day) corrected for the thermic effect of food of the extra energy intake. These data do not support the hypothesis that training as a distance runner results in metabolic adaptations that lower energy requirements in women.     

Resistance Training Preserves Fat‐free Mass Without Impacting Changes in Protein Metabolism After Weight Loss in Older Women

This study assessed the effects of resistance training (RT) on energy restriction–induced changes in body composition, protein metabolism, and the fractional synthesis rate of mixed muscle proteins (FSRm) in postmenopausal, overweight women. Sixteen women (age 68 ± 1 years, BMI 29 ± 1 kg/m², mean ± s.e.m.) completed a 16‐week controlled diet study. Each woman consumed 1.0 g protein/kg/day. At baseline (weeks B1–B3) and poststudy (weeks RT12–RT13), energy intake matched each subject's need and during weeks RT1–RT11 was hypoenergetic by 2,092 kJ/day (500 kcal/day). From weeks RT1 to RT13, eight women performed RT 3 day/week (RT group) and eight women remained sedentary (SED group). RT did not influence the energy restriction–induced decrease in body mass (SED ?5.8 ± 0.6 kg; RT ?5.0 ± 0.2 kg) and fat mass (SED ?4.1 ± 0.9 kg; RT ?4.7 ± 0.5 kg). Fat free mass (FFM) and total body water decreased in SED (?1.6 ± 0.4 and ?2.1 ± 0.5 kg) and were unchanged in RT (?0.3 ± 0.4 and ?0.4 ± 0.7 kg) (group‐by‐time, P ≤ 0.05 and P = 0.07, respectively). Protein–mineral mass did not change in either group (SED 0.4 ± 0.2 kg; RT 0.1 ± 0.4 kg). Nitrogen balance, positive at baseline (2.2 ± 0.3 g N/day), was unchanged poststudy. After body mass loss, postabsorptive (PA) and postprandial (PP) leucine turnover, synthesis, and breakdown decreased. Leucine oxidation and balance were not changed. PA and total (PA + PP) FSRm in the vastus lateralis were higher after weight loss. RT did not influence these protein metabolism responses. In summary, RT helps older women preserve FFM during body mass loss. The comparable whole‐body nitrogen retentions, leucine kinetics, and FSRm between groups are consistent with the lack of differential protein–mineral mass change.     

Determinants of Free-Living Energy Expenditure in Normal Weight and Obese Women Measured by Doubly Labeled Water

Total free-living energy expenditure (TEE) was measured in 9 normal weight controls and 5 obese women using the doubly labeled water (DLW) method. Resting energy expenditure (REE) and the thermic effect of food (TEF) were measured by indirect calorimetry and the energy cost of physical activity (PA) calculated by deduction, in order to quantify the components and identify determinants of free-living TEE. Although REE was quantitatively the major component of TEE in both groups, PA best explained the variability, contributing 76% to the variance in free-living TEE. The obese women had elevated values for TEE (12397+/-2565 vs. 8339+/-1787 kJ/d, mean+/-SD; p<0.00S), compared with the control women. PA (5071+/-2385 vs. 2552+/-1452; p<0.0S) and REE (6393+/-678 vs. 5084+/-259; p<0.000S) were also raised in the obese, whereas TEF was not significantly different between the groups, accounting for 7.6% of energy expenditure for the obese and 8% for the control subjects. Body weight was the single best determinant of mean daily free-living TEE across both groups. We conclude that PA and body weight are the main determinants of free-living TEE .     

Circulatory galanin levels increase severalfold with intense orthostatic challenge in healthy humans.

The purpose of this study was to test the hypothesis that plasma galanin concentration (pGal) is regularly increased in healthy humans with extensive orthostatic stress. Twenty-six test persons (14 men, 12 women) were brought to an orthostatic end point via a progressive cardiovascular stress (PCS) protocol consisting of 70 degrees head-up tilt plus increasing levels of lower body negative pressure until either hemodynamically defined presyncope or other signs of orthostatic intolerance occurred (nausea, clammy skin, excessive sweating, pallor of the skin). We further tested for possible gender, gravitational, and muscular training influences on plasma pGal responses: PCS was applied before and after 3 wk of daily vertical acceleration exposure training on a Human Powered Centrifuge. Test persons were randomly assigned to active (with bicycle work) or passive (without work) groups (seven men, six women in each group). Resting pGal was 26+/-3 pg/ml in men and 39+/-15 pg/ml in women (not significant); women had higher galanin responses (4.9-fold increase) than men (3.5-fold, P=0.017) to PCS exposure. Overall, PCS increased pGal to 186+/-5 pg/ml (P=0.0003), without significant differences between presyncope vs. orthostatic intolerance, pre- vs. postcentrifuge, or active vs. passive gravitational training. Increases in pGal were poorly related to synchronous elevations in plasma vasopressin. We conclude that galanin is regularly increased in healthy humans under conditions of presyncopal orthostatic stress, the response being independent of gravity training but larger in women than in men.     

Effect of gender on vestibular sympathoexcitation

Studies have suggested that premenopausal women are more prone to orthostatic intolerance than men. Additionally, it has been postulated that the vestibulosympathetic reflex is important in regulating postural-related changes in sympathetic activity. The purpose of the present study was to determine whether men and women differ in their sympathetic and cardiovascular responses to stimulation of the otolith organs elicited by head-down rotation (HDR). Heart rate (HR), arterial pressure, calf blood flow (CBF), and leg muscle sympathetic nerve activity (MSNA) were measured during 3 min of HDR in the prone posture in 33 women and 30 men. With the exception of HR (71 +/- 2 and 63 +/- 1 beats/min for women and men, respectively; P < 0.01), all baseline variables were not different between genders. There were no gender differences in responses to HDR. MSNA increased 72 +/- 33 units (43%) in the men and 88 +/- 15 units (59%) in the women during HDR (P < 0.01). CBF decreased [-0.6 +/- 0.1 (15%) and -0.5 +/- 0.1 (19%) ml. min(-1). 100 ml(-1)] and calf vascular resistance increased [8 +/- 2 (21%) and 11 +/- 3 (25%) units during HDR for men and women, respectively (P < 0.01)]. Both in the men and women, HR increased 2 +/- 1 beats/min (P < 0.01). These results demonstrate that sympathetic activation during HDR in the prone posture is similar in men and women. Therefore, these findings suggest that the vestibulosympathetic reflex is not different between healthy men and women.     

Influence of ascorbic acid on the thermic effect of feeding in overweight and obese adult humans

The thermic effect of feeding (TEF: increase in energy expenditure following acute energy intake) is an important physiological determinant of total daily energy expenditure and thus energy balance. Approximately 40% of TEF is believed to be mediated by sympathoadrenal activation and consequent beta-adrenergic receptor stimulation of metabolism. In sedentary adults, acute administration of ascorbic acid, a potent antioxidant, augments the thermogenic response to beta-adrenergic stimulation. We hypothesized that acute ascorbic acid administration augments TEF in sedentary overweight and obese adults. Energy expenditure was determined (ventilated hood technique) before and 4 h after consumption of a liquid-mixed meal (caloric equivalent 40% of resting energy expenditure (REE)) in 11 sedentary, overweight/obese adults (5 men, 6 women; age: 24 +/- 2 years; BMI: 28.5 +/- 1.0 kg/m(2) (mean +/- s.e.)) on two separate, randomly ordered occasions: during continuous intravenous administration of saline (placebo control) and/or ascorbic acid (0.05 g/kg fat-free mass). Acute ascorbic acid administration prevented the increase in plasma concentration of oxidized low-density lipoprotein in the postprandial state (P = 0.04), but did not influence REE (1,668 +/- 107 kcal/day vs.1,684 +/- 84 kcal/day; P = 0.91) or the area under the TEF response curve (33.4 +/- 2.4 kcal vs. 30.5 +/- 3.6 kcal; P = 0.52) (control vs. ascorbic acid, respectively). Furthermore, acute ascorbic acid administration had no effect on respiratory exchange ratio, heart rate, or arterial blood pressure in the pre- and postabsorptive states (all P > 0.64). These data imply that the attenuated TEF commonly observed with sedentary lifestyle and obesity is not modulated by ascorbic acid-sensitive oxidative stress.