Optical communications downlink from a low-earth orbiting 1.5U CubeSat.

In this article, we present the first demonstration of an optical communications downlink from a low-earth orbiting free-flying CubeSat. Two 1.5U vehicles, AC7-B&C, built under NASA's Optical Communications and Sensors Demonstration (OCSD) program were launched in November 2017 and subsequently placed into a 450-km, 51.6° inc. circular orbit. Pseudorandom data streams using on-off key (OOK) modulation were transmitted from AC-7B to a 40 cm aperture telescope located at sea level in El Segundo, CA. At 200 Mbps, without forward error correction (FEC), we achieved a 115-second link that was ~78% error free, with the remaining portion exhibiting an error rate below 1E-5. At the time of the engagement, the 1064-nm laser transmitter was operating at 2 W (half capacity) with a full width half maximum (FWHM) beam divergence of ~1 mrad, which was approximately double the anticipated pointing accuracy of the vehicle.

Omni scale rating of perceived exertion at ventilatory breakpoint by direct observation of children's kinematics.

Direct kinematic observation was used to measure ratings of perceived exertion at the ventilatory breakpoint (RPE-Vpt) in 10- to 14-yr.-old girls (n=22) and boys (n=22). RPE for the overall body, legs, and chest were simultaneously estimated by a trained observer and self-rated by a subject during treadmill exercise using the Children's OMNI-Walk/Run Scale. Subjects' heart rate and oxygen consumption were measured during each minute of exercise. Vpt for the girls and boys, respectively, were 64.2 and 66.5% VO2 max. RPE-Vpt ranged from 6.0 to 6.5 Overall, 7.1 to 7.6 Legs, and 5.0 to 5.5 Chest for both the observation and self-rating procedures. Responses indicated (a) RPE-Vpt (Overall, Legs, Chest) did not differ (p>.05) between the observer and self-rating procedures and (b) Observer RPE-Vpt-Legs was greater (p<.05) than RPE-Vpt-Chest. Findings validated direct kinematic observation to code group-normalized RPE-Vpt for girls and boys performing treadmill exercise.

Effect of exercise intensity on glucose and insulin metabolism in obese individuals and obese NIDDM patients.

OBJECTIVE: The primary purpose of this study was to evaluate the acute effect of exercise of differing intensity on plasma glucose and insulin responses to an oral glucose challenge. RESEARCH DESIGN AND METHODS: Six obese men and six obese men with NIDDM of similar age, weight, percentage body fat, and VO2peak participated in the study. Each subject underwent two 7-day exercise programs in a counterbalanced order at 2-week intervals. During each 7-day exercise period, the subjects cycled every day at a power output corresponding to 50% VO2peak for 70 min or 70% VO2peak for 50 min. Muscle glycogen utilization was estimated during exercise on day 7 using a [3H]glucose infusion technique in conjunction with indirect calorimetry. During the day before and after each 7-day exercise period, a 3-h oral glucose tolerance test (OGTT) was administered after a 12-h overnight fast. RESULTS: The average caloric expenditure did not differ between exercise at 50 and 70% VO2peak in both obese and obese NIDDM subjects. However, the carbohydrate oxidation was higher (P < 0.05) during exercise at 70 than 50% VO2peak in obese subjects (77 +/- 5 vs. 68 +/- 6 g) and obese NIDDM subjects (70 +/- 4 vs. 58 +/- 6 g). Muscle glycogen utilization was also higher (P < 0.05) during exercise at 70 than 50% VO2peak in obese subjects (59 +/- 9 vs. 30 +/- 7 g) and in obese NIDDM subjects (48 +/- 5 vs. 24 +/- 5 g). In obese subjects, plasma glucose response area during the OGTT did not change after 7 days of exercise at either 50 or 70% VO2peak. Plasma insulin response area during the OGTT also did not change after 7 days of exercise at 50% VO2peak. However, plasma insulin response area was reduced (P < 0.05) after 7 days of exercise at 70% VO2peak (9,644 +/- 1,783 vs 7,538 +/- 1,522 microU.ml-1.180 min-1). In obese NIDDM subjects, both plasma glucose and insulin response areas during the OGTT did not decrease after 7 days of exercise at either 50 or 70% VO2peak. CONCLUSIONS: It is concluded that the exercise-induced improvement in insulin sensitivity is influenced by exercise intensity in obese individuals. The improved insulin sensitivity after 7 days of exercise at 70% VO2peak in obese individuals may be related to greater muscle glycogen utilization during exercise. The lack of improvement in glucose tolerance and insulin sensitivity after 7 days of exercise at either 50 or 70% VO2peak in obese NIDDM patients may be due to the fact that the NIDDM patients selected in the present study were relatively hypoinsulinemic.

Use of the leg-to-leg bioelectrical impedance method in assessing body-composition change in obese women.

BACKGROUND: There is little information on whether bioelectrical impedance analysis (BIA) accurately predicts changes in body composition associated with energy restriction, exercise, or both. OBJECTIVE: We had 2 objectives: to determine the validity of the leg-to-leg BIA system in 1) estimating body composition in obese and nonobese women, with a cross-sectional design, and 2) assessing changes in body composition in obese women in response to 12 wk of energy restriction, exercise training, or both. DESIGN: Subjects were 98 moderately obese women (43.2 +/- 0.6% body fat, 45.0 +/- 1.1 y of age) and 27 nonobese control subjects (24.0 +/- 1.5% body fat, 43.5 +/- 2.5 y of age). Obese subjects were randomly divided into 1 of 4 groups, with fat-free mass, fat mass, and percentage body fat estimated with BIA and underwater weighing before and after 12 wk of intervention. The 4 groups were diet only (4.19-5.44 MJ/d), exercise only (five, 45-min sessions/wk at 78.5 +/- 0.5% of maximum heart rate), both exercise and diet, and control (no diet or exercise). RESULTS: No significant difference was found between underwater weighing and BIA in estimating the fat-free mass of the obese and nonobese women (all subjects combined, r = 0.78, P < 0.001, SEE = 3.7 kg) or in estimating decreases in fat mass during 12 wk of energy restriction, exercise, or both in obese subjects (F[3.85] = 1.45, P = 0.233). CONCLUSIONS: The leg-to-leg BIA system accurately assessed fat-free mass in obese and nonobese women, and changes in fat mass with diet alone or when combined with exercise.

Cytokine changes after a marathon race.

The influence of carbohydrate (1 l/h of a 6% carbohydrate beverage), gender, and age on pro- and anti-inflammatory plasma cytokine and hormone changes was studied in 98 runners for 1.5 h after two competitive marathon races. The marathoner runners were randomly assigned to carbohydrate (C, n = 48) and placebo (P, n = 50) groups, with beverages administered during the races in a double-blind fashion using color codes. Plasma glucose was higher and cortisol was lower in the C than in the P group after the race (P < 0.001). For all subjects combined, plasma levels of interleukin (IL)-10, IL-1 receptor antagonist (IL-1ra), IL-6, and IL-8 rose significantly immediately after the race and remained above prerace levels 1.5 h later. The pattern of change in all cytokines did not differ significantly between the 12 women and 86 men in the study and the 23 subjects > or =50 yr of age and the 75 subjects <50 yr of age. The pattern of change in IL-10, IL-1ra, and IL-8, but not IL-6, differed significantly between the C and the P group, with higher postrace values measured for IL-10 (109% higher) and IL-1ra (212%) in the P group and for IL-8 (42%) in the C group. In conclusion, plasma levels of IL-10, IL-1ra, IL-6, and IL-8 rose strongly in runners after a competitive marathon, and this was not influenced by age or gender. Carbohydrate ingestion, however, had a major effect in attenuating increases in cortisol and two anti-inflammatory cytokines, IL-10 and IL-1ra.

Carbohydrate ingestion influences skeletal muscle cytokine mRNA and plasma cytokine levels after a 3-h run.

Sixteen experienced marathoners ran on treadmills for 3 h at approximately 70% maximal oxygen consumption (Vo(2 max)) on two occasions while receiving 1 l/h carbohydrate (CHO) or placebo (Pla) beverages. Blood and vastus lateralis muscle biopsy samples were collected before and after exercise. Plasma was analyzed for IL-6, IL-10, IL-1 receptor agonist (IL-1ra), IL-8, cortisol, glucose, and insulin. Muscle was analyzed for glycogen content and relative gene expression of 13 cytokines by using real-time quantitative RT-PCR. Plasma glucose and insulin were higher, and cortisol, IL-6, IL-10, and IL-1ra, but not IL-8, were significantly lower postexercise in CHO vs. Pla. Change in muscle glycogen content did not differ between CHO and Pla (P = 0.246). Muscle cytokine mRNA content was detected preexercise for seven cytokines in this order (highest to lowest): IL-15, TNF-alpha, IL-8, IL-1beta, IL-12p35, IL-6, and IFN-gamma. After subjects ran for 3 h, gene expression above prerun levels was measured for five of these cytokines: IL-1beta, IL-6, and IL-8 (large increases), and IL-10 and TNF-alpha (small increases). The increase in mRNA (fold difference from preexercise) was attenuated in CHO (15.9-fold) compared with Pla (35.2-fold) for IL-6 (P = 0.071) and IL-8 (CHO, 7.8-fold; Pla, 23.3-fold; P = 0.063). CHO compared with Pla beverage ingestion attenuates the increase in plasma IL-6, IL-10, and IL-1ra and gene expression for IL-6 and IL-8 in athletes running 3 h at 70% Vo(2 max) despite no differences in muscle glycogen content.

Influence of carbohydrate ingestion on immune changes after 2 h of intensive resistance training.

Thirty strength-trained subjects were randomized to carbohydrate (CHO) or placebo (Pla) groups and lifted weights for 2 h (10 exercises, 4 sets each, 10 repetitions, with 2- to 3-min rest intervals). Subjects received 10 ml x kg(-1) x h(-1) CHO (6%) or Pla beverages during the weight training bout. Blood, saliva, and vastus lateralis muscle biopsy samples were collected before and after exercise. Blood cell counts were determined, and plasma was analyzed for IL-6, IL-10, IL-1 receptor antagonist (IL-1ra), IL-8, and cortisol. Muscle was analyzed for glycogen content and relative gene expression of 13 cytokines (IL-1alpha, IL-1beta, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p35, IL-12p40, IL-15, IFN-gamma, TNF-alpha) by use of real-time quantitative RT-PCR. Significant but modest increases were measured for plasma IL-6, IL-10, IL-1ra, and IL-8, but the pattern of increase did not differ between CHO and Pla groups. The rate of decrease in muscle glycogen content did not differ between CHO and Pla (P = 0.463). Muscle cytokine mRNA was detected preexercise for IL-1beta, IL-6, IL-15, IL-8, and TNF-alpha, and of these, IL-1beta, IL-6, IL-8, and TNF-alpha were significantly increased after the 2-h weight training bout. The increase in mRNA (fold difference from preexercise) did not differ between CHO and Pla groups. In summary, CHO vs. Pla ingestion did not alter modest increases measured for plasma IL-6, IL-10, IL-1ra, and IL-8, and muscle gene expression for IL-1beta, IL-6, IL-8, and TNF-alpha in strength-trained subjects lifting weights intensively for 2 h.

Influence of obesity on immune function.

OBJECTIVE: To compare immune function in obese and nonobese subjects. DESIGN: Obese and nonobese subjects were compared cross-sectionally. To test for the influence of other factors on immunity, aerobic fitness, psychological well-being, and serum levels of glucose, triglycerides, and cholesterol were measured and included in multiple regression models to determine their comparative effects. SUBJECTS/SETTING: Community-based subjects included 116 obese women (age = 44.3 +/- 9.7 years, body mass index = 33.2 +/- 6.5) and 41 nonobese women (age = 42.2 +/- 10.9 years, body mass index = 21.2 +/- 1.9). STATISTICAL ANALYSES PERFORMED: Independent t tests, Pearson product moment correlations, and stepwise multiple regression procedures. RESULTS: Obesity was linked to elevated leukocyte and lymphocyte subset counts (except for natural killer and cytotoxic/suppressor T cells), suppressed mitogen-induced lymphocyte proliferation (an index of T- and B-cell function), higher monocyte and granulocyte phagocytosis and oxidative burst activity, and normal activity of natural killer cells. APPLICATIONS/CONCLUSIONS: These data support the contention that obesity is associated with alterations in immune function. Further research is needed to link immunosuppression with the previously reported elevated risk of infection among the obese.

Effects of exercise training on gallbladder function in an obese female population.

PURPOSE: Aerobic exercise may influence gallstone disease pathogenesis through its effect on gallbladder motility. The purpose of this investigation was to examine the effects of exercise training on gallbladder emptying in obese women. METHODS: Twenty-seven obese subjects were randomized into one of two groups: exercise (E) (five 45-min brisk walking sessions per week at 75.2 +/- 0.5% of maximum heart rate) and controls (C). Gallbladder function via cholescintigraphy, cardiorespiratory fitness, and body composition were measured in all subjects before and after a 12-wk intervention period. In each cholescintigraphy trial subjects ingested an 8-oz liquid meal 45 min after injection of 99mTc disofenin to promote gallbladder emptying. Gallbladder areas were then scanned for 60 s and then every 5 min for 60 min. RESULTS: VO2max increased significantly by 9% for E when compared with that for C (P < 0.001). Within E postprandial gallbladder ejection fraction (EF) increased significantly after training (39.5 +/- 4.9% to 54.7 +/- 6.5%, P < 0.05); however, this 15.2% increase in EF was not significantly greater than the change reported in the controls. CONCLUSIONS: Results indicate that 12 wk of moderate exercise training does improve cardiorespiratory fitness but does not significantly effect gallbladder emptying in obese women.

The effects of acute exercise on gallbladder function in an adult female population.

It has been suggested that aerobic exercise influences gallstone disease pathogenesis through its effects on gallbladder motility. The purpose of the present investigation was to examine the effects of acute aerobic exercise on gallbladder emptying. Gallbladder function was evaluated, via cholescintigraphy, in 12 healthy females after undergoing two experimental trials [i.e., postprandial (P) and exercise + postprandial (E + P))]. In the E + P trial, 60 min after injection of 99mTc disofenin, subjects exercised for 30 min at 65.3 +/- 0.9%, (mean +/- SEM) of VO2 peak on a recumbent leg ergometer, and then ingested 8 oz of a liquid meal to promote gallbladder emptying. In the P trial the meal was administered at the same time relative to the E + P trial; however, for the 30 min prior to meal ingestion subjects remained in a resting supine position. Postprandial gallbladder ejection fraction (EF) was nonsignificantly higher in the E + P trial (49.4 +/- 5.1%) than in the P trial (46.6 +/- 6.7%). Results of this study also indicated that during a fasted state the gallbladder undergoes significant periods of spontaneous emptying both at rest EF = 25 +/- 5.6% (P < 0.02) and during exercise EF = 17 +/- 4.3% (P < 0.01). In conclusion, the results of this study indicate that 30 min of aerobic exercise at 65% of VO2 peak does not effect gallbladder motility in a healthy, premenopausal, female population.

Substrate utilization and glucose turnover during exercise of varying intensities in individuals with NIDDM.

PURPOSE: This investigation was undertaken to examine substrate utilization and glucose turnover during exercise of varying intensities in NIDDM patients. METHODS: Six male NIDDM patients (N) and six male controls (C) of similar age, body weight, % body fat, and VO2peak were studied in two experimental sessions administered in a randomized counterbalanced order. During each session the subjects cycled at a power output corresponding to 50% of VO2peak or 70% of VO2peak. Duration of exercise was adjusted so that energy expenditure (EE) was equal in both the 50% and 70% trials. Isotope infusion technique and indirect calorimetry were used to assess substrate utilization and glucose turnover during exercise. RESULTS: Rates of carbohydrate (CHO) and lipid oxidation increased (P < 0.05) during both the 50% and 70% trials. Rates of CHO oxidation were greater (P < 0.05) during the 70% than during the 50% trial. However, rates of lipid oxidation were similar in the two trials. No differences in rates of CHO and lipid oxidation were observed in N and C. Rates of hepatic glucose production (Ra) and plasma glucose utilization (Rd) increased (P < 0.05) during exercise, and the increases were similar in the 50% and 70% trials. Ra did not differ between N and C. However, Rd was greater (P < 0.05) in N than in C. Plasma glucose concentration decreased (P < 0.05) in N, with the decrease being similar in the 50% and 70% trials. In contrast, plasma glucose concentration remained unchanged during both the 50% and 70% trials in C. CONCLUSIONS: Exercise results in a greater increase in plasma glucose utilization in patients with NIDDM compared with that in normal individuals, and this increase mediates the decline in plasma glucose concentrations in patients with NIDDM. Under isocaloric conditions, the changes in plasma glucose utilization and plasma glucose concentrations are similar during exercise of varying intensities. Despite a greater glucose utilization, carbohydrate and fat oxidation are similar in the two groups and their relations to exercise intensity are not altered by NIDDM.

Metabolic efficiency during arm and leg exercise at the same relative intensities.

This study was conducted to compare gross efficiency (GE), net efficiency (NE), work efficiency (WE), and delta efficiency (DE) between arm crank and cycle exercise at the same relative intensities. Eight college-aged males underwent two experimental trials presented in a randomized counterbalanced order. During each trial subjects performed three intermittent 7-min exercise bouts separated by 10-min rest intervals on an arm or semirecumbent leg ergometer. The power outputs for the three bouts of arm crank or cycle exercise corresponded to 50, 60, and 70% of the mode-specific VO2peak. GE, NE, and WE were determined as the ratio of Kcal.min-1 equivalent of power output to Kcal.min-1 of total energy expended, energy expended above rest and energy expended above unloaded exercise, respectively. DE was determined as the ratio of the increment of Kcal.min-1 of power output above the previous lower intensity to the increment of kcal.min-1 of total energy expended above the previous lower intensity. GE and NE did not differ between arm crank and cycle exercises. However, WE was lower (P < 0.05) during arm crank than cycle exercise at 50, 60, and 70% VO2peak. DE was also lower (P < 0.05) during arm crank than cycle exercise at delta 50-60 and at delta 60-70% VO2peak. It is concluded metabolic efficiency as determined by work and delta efficiency indices was lower during arm crank compared with cycle exercise at the same relative intensities. These findings add to the understanding of the difference in metabolic efficiency between upper and lower body exercise.

Psychological response to exercise training and/or energy restriction in obese women.

OBJECTIVE: The effect of 12 weeks of exercise training (five 45-minute walking sessions/week at 60% to 75% maximum heart rate) and/or moderate energy restriction (4.19 to 5.44 MJ or 1200 to 1300 kcal/day) on psychological general well-being (GWB) and profile of mood states (POMS) was studied in obese women (n = 91, age 45.6 +/- 1.1 years, body mass index 33.1 +/- 0.6 kg/m2). METHODS: Subjects were randomized to one of four groups: control (C); exercise (E); diet (D); and exercise and diet (ED). Psychological variables were measured in all subjects at three timepoints--prestudy, 3 weeks, and poststudy--and analyzed using a 4 x 3 repeated measures design. RESULTS: GWB but not POMS was improved in ED (but not E or D) relative to C poststudy, especially in four of six subscales: freedom from health concern or worry, life satisfaction; cheerful versus depressed mood; and relaxed versus tense feelings. CONCLUSION: These data demonstrate that the combination of moderate energy restriction and exercise training during a 12-week period improves psychological general well-being scores but not mood states in obese subjects.

Validity of leg-to-leg bioelectrical impedance measurement in males.

BACKGROUND: This study determined the validity of the leg-to-leg bioelectrical impedance analysis (BIA) system (Tanita Body Fat Analyzer, TBF 105, Tanita Corporation of America, Inc., Arlington Heights, IL) in estimating body composition in males. EXPERIMENTAL DESIGN: Fat-free mass (FFM) was estimated using BIA and underwater weighing, and compared. SETTING: Subjects were recruited from the community. PARTICIPANTS: Heterogeneous group of males (N=192) was recruited, with a mean+/-SD age of 39.0+/-16.8 yrs; body mass index, 26.0+/-4.0 kg/m2, percent body fat, 18.1+/-8.9 percent. MEASURES: Prior to BIA testing, subjects were required to adhere to standard BIA testing guidelines, and bioelectrical impedance was measured in subjects standing erect with bare feet on the analyzer's footpads, and wearing a swimsuit. Underwater weighing was conducted using standard procedures, with direct measurement of residual volume. RESULTS: A Bland-Altman plot of difference between FFM measured by underwater weighing and BIA versus average FFM by the two methods showed no systematic difference (mean difference, 0.07+/-3.5 kg). FFM was estimated at 66.3+/-8.6 kg with underwater weighing, and 66.2+/-7.7 kg with BIA (r=0.92, p<0.001; SEE 3.5 kg). CONCLUSIONS: These data indicate that the leg-to-leg bioelectrical impedance system accurately assesses FFM in a heterogenous group of males when compared to underwater weighing.

Effect of carbohydrate substrate availability on ratings of perceived exertion during prolonged exercise of moderate intensity.

This investigation examined the effect of carbohydrate substrate availability on ratings of perceived exertion (RPE) during cycling at moderate intensity to exhaustion and the relation between submaximal endurance performance and RPE obtained following 2 hr. of cycling at moderate intensity. Seven male cyclists performed two exercise trials at power output corresponding to 70% of their peak oxygen uptake until exhaustion. Subjects ingested either a 6% glucose/sucrose solution at the rate of 0.6 g.kg-1 (Body Weight).hr.-1 or an equal volume of artificially flavored placebo every 20 min. throughout the exercise trials. RPE for the legs, chest, and over-all body, and oxygen consumption, expired ventilation, carbohydrate oxidation rate, and blood concentrations of glucose, glycerol, and lactate were measured every 20 min. throughout exercise and at exercise termination. Statistical analysis of these dependent variables indicates that (1) an exercise-induced decrease in blood-borne carbohydrate substrate intensifies leg and over-all perceptions of exertion during the later stages of prolonged cycling at 70% VO2peak. (2) Factors other than availability of blood-borne carbohydrate substrate may influence perceptual intensity at exhaustion. (3) Ratings of perceived exertion for the legs and over-all body obtained after 2 hr. of cycling at moderate intensity may be useful in predicting submaximal endurance performance.

The new National Collegiate Athletic Association wrestling weight certification program and sport-seasonal changes in body composition of college wrestlers.

Changes in body composition of college-age wrestlers (N = 21, 19.0 +/- 0.2 years of age, 8.2 +/- 0.6 years of experience) were studied throughout the season after implementation of the new National Collegiate Athletic Association (NCAA) wrestling weight certification (WWC) program. Wrestlers were divided into 2 groups, starters (n = 10) and nonstarters (n = 11), based on the number of completed matches during the 1998-1999 season. Body density was measured via hydrostatic weighing, with residual volume determined via the nitrogen washout technique. Hydration was assessed by measuring specific gravity of urine (Usg). For body mass and fat-free mass (FFM), a significant difference in the pattern of change was found (p < 0.05), highlighted by a decrease in body mass (-3.0%, -2.5 kg, -5.8 lb) and a maintenance of FFM from preseason to peak season for the starters. The pattern of change over time was significantly different for refractometry Usg (p < 0.01) but not for the test strip Usg (p = 0.54). No significant interaction effects were seen for percentage of body fat or fat mass. Significant time main effects were found for percentage of body fat, body mass, fat mass, FFM, and refractometry Usg. Taken together, the results of this investigation demonstrate that collegiate wrestlers lose body mass but maintain FFM throughout the season, which may in part be associated with the new NCAA WWC program.

Influence of skinfold sum and peak VO(2) on immune function in children.

OBJECTIVE: To measure the relationship of skinfold sum and peak VO(2) power with immune function in children. DESIGN: Cross-sectional, with all children tested twice during a 2 month period for peak VO(2), sum of two skinfolds, and immune function, with data from the two measures averaged and then correlated (alpha level, < or = 0.01). Immune measures included leukocyte and lymphocyte subset counts, delayed-typed hypersensitivity (DTH), global IgG antibody response over 4 weeks to pneumococcal vaccination (pIgG), salivary IgA concentration (sIgA), PHA-stimulated lymphocyte proliferation (PHA-SLP), natural killer cell activity (NKCA), and granulocyte and monocyte phagocytosis and oxidative burst activity. SUBJECTS: Seventy-three children (n=42 males, n=31 females) ranging in age from 7 to 13 y (mean+/-s.d. age, 9.9+/-1.7 y). The mean skinfold sum was 28.9+/-17.1 mm, and peak VO(2) 45.8+/-8.1 ml/kg/min. RESULTS: Peak VO(2), skinfold sum, and immune measures did not differ significantly by age or gender. Therefore, correlations were made on combined indices for all subjects. Peak VO(2) and the skinfold sum were not significantly correlated with NKCA, oxidative burst activity, plgG or DTH. Peak VO(2) was negatively correlated with monocyte phagocytosis (r=-0.30, P=0.012) and positively correlated with PHA-SLP (6.25 microg/ml; r=0.35, P=0.004). The skinfold sum was positively correlated with the total leukocyte count (r=0.39, P<0.001), granulocyte count (r=0.36, P=0.002), monocyte count (r=0.38, P=0.001), monocyte phagocytosis (r=0.41, P<0.001), granulocyte phagocytosis (r=0.35, P=0.003), and sIgA (r=0.32, P=0.006), and negatively correlated with PHA-SLP (6.25 microg/ml; r=-0.39, P=0.001). CONCLUSIONS: Data from this study indicate that a high skinfold sum is related to elevated leukocyte subset counts and monocyte/granulocyte phagocytosis, and low PHA-SLP in children.

Influence of diet and/or exercise on body composition and cardiorespiratory fitness in obese women.

The purpose of this study was to measure the influence of diet, exercise, or both on body composition and cardiorespiratory fitness in obese women. Ninety-one obese subjects were randomized into one of four groups: diet (D) (4.19-5.44 MJ or 1,200-1,300 kcal/day), exercise (E) (five 45-min sessions at 78.5+/-0.5% maximum heart rate), exercise and diet (ED), and controls (C). Maximal aerobic power and body composition were measured in all subjects before and after a 12-week diet intervention period. Subjects in D and ED lost 7.8+/-0.7 and 8.1+/-0.6 kg body mass, with no significant change for E relative to C. Losses of percent body fat and fat mass were significantly greater in D and ED but not in E relative to C. The change in VO2max was greater in ED and E but not D when compared to C. Results indicate that moderate aerobic exercise training during a 12-week period has no discernible effects on body composition but does improve cardiorespiratory fitness in dieting obese women.

Effect of carbohydrate ingestion subsequent to carbohydrate supercompensation on endurance performance.

This investigation determined whether carbohydrate ingestion during prolonged moderate-intensity exercise enhanced endurance performance when the exercise was preceded by carbohydrate supercompensation. Seven male trained cyclists performed two trials at an initial power output corresponding to 71 +/- 1% of their peak oxygen consumption. During the trials, subjects ingested either a 6% glucose/sucrose (C) solution or an equal volume of artificially flavored and sweetened placebo (P) every 20 min throughout exercise. Both C and P were preceded by a 6-day carbohydrate supercompensation procedure in which subjects undertook a depletion-taper exercise sequence in conjunction with a moderate- and high-carbohydrate diet regimen. Statistical analysis of time to exhaustion, plasma glucose concentration, carbohydrate oxidation rate, fat oxidation rate, and plasma glycerol concentration indicated that in spite of a carbohydrate supercompensation procedure administered prior to exercise, carbohydrate ingestion during exercise can exert an additional ergogenic effect by preventing a decline in blood glucose levels and maintaining carbohydrate oxidation during the later stages of moderate-intensity exercise.