Salivary immunoglobulin A in healthy adolescent females: effects of maximal exercise, physical activity, body composition and diet.

BACKGROUND: The primary purpose of this study was to examine the effect of acute maximal exercise (VO2max test) on salivary immunoglobulin A (SIgA) responses in adolescent females. A secondary aim was to examine the relationship between resting SIgA levels and VO2max, physical activity, body composition, and diet. METHODS: Fifty healthy female adolescents completed a laboratory-based VO2max test, assessment of body composition via hydrodensitometry, a validated physical activity questionnaire (PAQ-A), and a three-day food diary. Unstimulated saliva was collected before, and 5 and 120 minutes after VO2max testing. Absolute SIgA (µg/mL) concentration was determined using an enzyme-linked immunosorbent assay. Secretion rate of SIgA (µg/min) was calculated by multiplying absolute SIgA concentration by saliva flow rate (SFR, µL/min). RESULTS: A significant increase in absolute SIgA concentration (146.8±59.2 µg/mL) was noted immediately after VO2max testing (P<0.05) and returned to pre-exercise levels (120.1±54.1 µg/mL) by 120-min post-exercise (P>0.05). No significant VO2max test effects were observed for SIgA secretion rate and SFR (P>0.05). VO2max values (41.92±6.36 mL/kg/min) were correlated with body fat percentage (r=-0.59; P<0.01), PAQ-A total score (r=0.48; P<0.01), and acute changes in absolute SIgA levels (r=0.28; P<0.05). No significant associations were observed between dietary measures and resting SIgA levels or SFR (P>0.05) except for dietary fiber which correlated with resting absolute SIgA concentration (r=0.29; P<0.05). CONCLUSIONS: Findings indicate that acute graded maximal exercise results in a transient increase in absolute SIgA concentration and that these changes are associated with individual VO2max values.

SIgA and Upper Respiratory Syndrome During a College Cross Country Season.

We examined the changes in salivary immunoglobulin A (SIgA) and the incidence of upper respiratory syndrome (URS) throughout a college cross-country season as well as the acute effect of a VO 2max test on SIgA. Subjects were 22 cross country athletes (XC) (20.7±0.3 years) and 23 matched controls (C) (20.4±0.2 years). Saliva samples were collected pre and post VO2max and at four training time points (August - November). Weekly logs indicating S&S of URS from which a total symptom score (TSS) was calculated were collected. There was a significant decrease in SIgA F(1,43)=10.742, p<0.001 and the secretion rate of SIgA F(1,43)=15.617, p<0.001 for XC at time points two through four. XC was also significantly lower than controls in those two variables across those time points. The secretion rate of SIgA and URS were negatively correlated at time point four R2=0.443, F(4,22)=26.9, p=0.001. There was a significant acute post exercise decrease in the secretion rate of SIgA, pre (M=21.44, SEM=3.95) and post (M=14.5, SEM=3.0), t(1,21)=2.185, p=0.039. Prolonged training resulted in decreased mucosal SIgA.

Resting energy expenditure and delayed-onset muscle soreness after full-body resistance training with an eccentric concentration.

The purpose of this investigation was to determine the effect of an acute bout of high-volume, full-body resistance training with an eccentric concentration on resting energy expenditure (REE) and indicators of delayed-onset muscle soreness (DOMS). Eight resistance trained (RT) and eight untrained (UT) participants (mean: age = 23.5 years; height = 180.76 cm; weight = 87.58 kg; body fat = 19.34%; lean mass = 68.71 kg) were measured on four consecutive mornings for REE and indicators of DOMS: creatine kinase (CK) and rating of perceived muscle soreness (RPMS). Delayed-onset muscle soreness was induced by performing eight exercises, eight sets, and six repetitions using a 1-second concentric and 3-second eccentric muscle action duration. A two-factor repeated-measures analysis of variance revealed that REE was significantly (p < 0.05) elevated at 24, 48, and 72 hours post compared with baseline measures for both UT and RT groups. Ratings of perceived muscle soreness were significantly elevated within groups for UT and RT at 24 and 48 hours post and for UT only at 72 hours post compared with baseline (p < 0.05). Nonparametric analyses revealed that CK was significantly increased at 24 hours post for both UT and RT and at 48 and 72 hours post for UT only compared with baseline (p < 0.05). Resting energy expenditure and indicators of DOMS were higher in UT compared with RT on all measures, but no significant differences were determined. The main finding of this investigation is that full-body resistance training with an eccentric concentration significantly increased REE up to 72 hours postexercise in UT and RT participants.

Effects of caffeine on linear and nonlinear measures of heart rate variability before and after exercise.

Caffeine intake is associated with an increase in heart rate (HR) variability. This study sought to examine the effects of caffeine on HR variability measures before and during progressive exercise in 11 healthy volunteers in a double-blind randomized and counterbalanced placebo-controlled paradigm. As expected, there were significant increases in HR and decreases in HR variability after exercise during both placebo and caffeine conditions; however, pre-exercise caffeine condition was associated with a significant increase of HR variability, especially in the high-frequency range (0.15-0.5 Hz), and also approximate entropy (APEN), which is usually attributed to cardiac vagal function. But during progressive exercise, caffeine intake resulted in a greater decrease of HF power as well as HR APEN. Caffeine also was associated with significantly higher LF power during exercise compared to the placebo condition. These results suggest that caffeine may have different effects on HR variability at rest, compared to exercise. These findings may have implications for patients with cardiac illness and anxiety, depression, and psychotic disorders who use beverages containing excessive caffeine.

Promoting healthful diets and exercise: efficacy of a 12-week after-school program in urban African Americans.

This study examined the effectiveness of a unique extracurricular after-school initiative designed to promote healthy diets and exercise in urban African Americans. The Students and Parents Actively Involved in Being Fit after-school program was offered for 12 weeks to students and their parents/guardians at an urban middle school. Specific aims of the intervention were to increase participants' vegetable and fruit intake by using established 5 A Day for Better Health educational resource materials/activities and to affect their health-related fitness through dance, games, and fitness activities. Fifty-six children and 25 parents/guardians completed a standard battery of evaluations before and after the program. Pre-post pairwise t test revealed that both children and their parents/guardians showed an increase in fruit consumption and a reduction in diastolic blood pressure (P <.05). Moreover, children showed improvements in systolic blood pressure and fruit juice, salad, and nonfried potato consumption while parents/guardians showed a decrease in body fat, body mass index, and endurance walk/run time (P <.05). Overall, findings indicate that children tended to gain more diet-related benefits while parents/guardians tended to derive more fitness-related benefits. After-school programs like the Students and Parents Actively Involved in Being Fit initiative can potentially contribute to improved health levels in urban African Americans.

Mucosal IgA and URTI in American college football players: a year longitudinal study.

PURPOSE: The purpose of this study was: (a) to evaluate secretory immunoglobulin A (s-IgA) over a 12-month time period in college football players, and (b) to assess which of the commonly used standard methods of reporting s-IgA, either alone or in combination, serves as the best predictor of incidence of upper respiratory tract infection (URTI). METHODS: One hundred college-aged males (75 varsity college football athletes, 25 nonfootball controls) were studied at eight points over a 12-month period. Resting mucosal IgA, protein and osmolality levels were determined from saliva using established procedures. In addition, incidence of URTI over the 12-month study duration was calculated from completed standard research logs. Repeated-measures ANOVA were conducted on the dependent variables and eight separate stepwise multiple regression analyses were conducted to predict the dependent variable "number of colds" by the independent variables, s-IgA, saliva flow rate, secretion rate of s-IgA, protein, s-IgA:protein, osmolality and s-IgA:osmolality at each data collection point. RESULTS: There was a significant main effect for group, time, and the group x time interaction for s-IgA, the secretion rate of s-IgA, and the number of colds. In the regression model, the only variable that made a significant contribution to the variance at all time points was the secretion rate of s-IgA. CONCLUSION: These findings suggest that a season of training in American football results in a significant decrease in both s-IgA and the secretion rate of s-IgA as well as an increase in the incidence of URTI. Among the various methods commonly employed to express s- IgA levels, the secretion rate of s-IgA may be the most useful clinical biomarker to predict the incidence of URTI.

Effects of ginseng on secretory IgA, performance, and recovery from interval exercise.

PURPOSE: This study examined the efficacy of ginseng to modulate secretory immunoglobulin A (SIgA), exercise performance, and recovery from repeated bouts of strenuous physical exertion. METHODS: Using a double-blind, placebo-controlled, randomized design, 38 active healthy adults supplemented their diets with a standardized ginseng concentrate (400 mg.d-1 of G115; equivalent to 2 g of Panax ginseng C.A. Meyer root material) or placebo (lactose) for 8 wk. Before and after the intervention, each subject performed three consecutive 30-s Wingate tests interspersed with 3-min recovery periods under controlled laboratory conditions. SIgA secretion rate (S-SIgA) and the relation of SIgA to total protein were calculated from measures of saliva flow rate (SFR), and absolute SIgA and salivary protein concentrations in timed, whole unstimulated saliva samples collected before and after exercise testing. Peak and mean mechanical power output (W.kg-1) was measured with an infrared-beam optical-sensor array, and exercise recovery heart rate (HRR) was determined electrocardiographically. RESULTS: Twenty-seven subjects (12 placebo, 15 ginseng) completed the study. Compared with rest, S-SIgA, SIgA:protein ratio, and SFR were lower after exercise at baseline (P < 0.05). Similarly, both peak and mean mechanical power output declined (P < 0.01) across consecutive Wingate tests. Postintervention minus preintervention change scores for salivary parameters, exercise performance, and HRR were similar between ginseng- and placebo-treated groups (P > 0.05). CONCLUSION: These findings do not support the hypothesis that ginseng may affect mucosal immunity as indicated by changes in secretory IgA at rest and after an exercise induced state of homeostatic disturbance. Supplementation with ginseng fails to improve physical performance and heart rate recovery of individuals undergoing repeated bouts of exhausting exercise.