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Biomedical subjects

D A Henson

Publications and source records attributed to D A Henson.

At least 19 recordsLinked to original sources
PubMed2003

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.

Administration, Oral↗
PubMed2003

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.

Adult↗
PubMed2003

Immune and oxidative changes during and following the Western States Endurance Run.

Changes in immune and oxidative stress parameters were measured in ultramarathon runners competing in the 160-km Western States Endurance Run. Forty-five runners agreed to provide blood and saliva samples the morning before the race event, at the 90-km aid station, and 5 - 10 min post-race. Upper respiratory tract infection (URTI) during the two-week period post-race was assessed retrospectively by telephone interviews. Forty subjects completed 90-km (race time, 13.1 +/- 0.3 h), and 31 completed the 160-km race event (27.0 +/- 0.4 h). The blood neutrophil and monocyte counts rose 249 % and 214 %, respectively, in the 31 finishers. Salivary IgA (sIgA) secretion rate decreased significantly from 508 +/- 40 micro g/min pre-race, to 287 +/- 39 micro g/min at 90-km, and 254 +/- 30 micro g/min post-race (50 % decrease). Significant increases were measured in cytokines at 90-km and post-race, with post-race IL-10 increasing 9.5-fold, IL-1ra 6.1-fold, IL-6 50.2-fold, and IL-8 2.5-fold over pre-race levels. Post-race indicators of oxidative stress, F (2)-isoprostane and lipid hydroperoxides, increased 33 % and 88 %, respectively. Pearson product-moment correlations revealed positive correlations at 90-km between F (2)-isoprostane and IL-6 (r = 0.31, p = 0.048), IL-10 (r = 0.31, p = 0.050), and IL-8 (r = 0.43, p = 0.005), but no other significant relationships between immune and oxidative stress indicators at 90-km and post-race. In the group of runners completing at least 90 km of the race, 26 % reported an URTI episode during the two-week period post-race. A low sIgA secretion rate at 90-km was the best predictor of post-race URTI (173 +/- 34 micro g/min in those who later acquired URTI compared to 325 +/- 40 micro g/min in those without URTI, p = 0.007). In conclusion, a modest correlation was found between cytokines and F (2)-isoprostane at 90-km when the greatest oxidative stress occurred, but no other significant correlations in immune and oxidative stress indicators during and following a 160-km ultramarathon race event were noted. About one in four ultramarathoners reported URTI during the two-week period post-race, and a low sIgA secretion rate mid-race best predicted URTI occurrence.

Adult↗
PubMed2002

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.

Adolescent↗
PubMed2002

Change in salivary IgA following a competitive marathon race.

The influence of carbohydrate (1 l/h of a 6 % carbohydrate beverage), gender, and age on salivary IgA (sIgA) changes and incidence of upper respiratory tract infection (URTI) was studied in 98 runners following two competitive marathon races. The pattern of change in sIgA concentration differed significantly between carbohydrate (C) (N = 48) and placebo (P) (N = 50) groups, with higher post-race values measured in P. However, when this was adjusted for saliva protein concentration and saliva secretion rate, no difference between groups was measured. For all subjects combined, sIgA concentration, saliva IgA: protein ratio (spIgA), and sIgA secretion rates fell significantly (21 %, 31 %, and 25 %, respectively) below pre-race levels by 1,5-h post-race (p < 0.001). The pattern of change in all saliva measures did not differ significantly between the 12 women and 86 men in this study, and between the 23 older (> or =50 yr) and 75 younger (< 50 yr) subjects. Ninety-three subjects returned health/sickness logs, and of these, 16 (17 %) reported developing URTI during the 15-d period following the race event. The 1.5-h post-race spIgA concentration, but not sIgA concentration or secretion rate, was lower in runners reporting URTI compared to those who did not (254 +/- 30 and 388 +/- 26 microg*g(-1), respectively, p = 0.002), and this was negatively correlated with the post-race plasma cortisol concentration (r = -0.36, p < 0.001). Of the 16 runners, six were in the C group and 10 in the P group (Chi square = 1.11, p = 0.293). In conclusion, the output of sIgA decreased in runners following a competitive marathon, and this was not influenced by carbohydrate ingestion, age, or gender.

Adult↗
PubMed2001

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.

Adult↗
PubMed2000

Saliva immunoglobulins in elite women rowers.

Saliva immunoglobulins (sIgA, sIgG, and sIgM) and upper respiratory tract infection (URTI) rates were evaluated in 20 elite female rowers and 19 nonathletes. Also, the influence of carbohydrate versus placebo beverage consumption on saliva immunoglobulin responses to rowing training sessions was measured in 15 rowers and in 5 non-exercising rowers. Saliva samples were collected 1 day before, and 5-10 min and 1.5 h after rowing or rest. Pre-exercise sIgA (but not sIgG or sIgM) concentration was 77% higher in the rowers compared to nonathletes (P < 0.001). Health records kept over 2 months revealed mean 5.2 (SEM 1.2) and 3.3 (SEM 1.1) days with URTI symptoms for the rowers and controls, respectively. For all 39 subjects, and for the 20 rowers separately, no significant correlation was found between URTI symptoms or insulin, cortisol, and growth hormone concentrations and pre-exercise or exercise-related changes in saliva immunoglobulin concentrations or secretion rates. The patterns of change in saliva immunoglobulin concentration and secretion rate did not differ between the carbohydrate and placebo rowing trials, or between exercised and rested athletes. These data indicated an increased sIgA concentration in the female elite rowers compared to the nonathletes, no association between saliva immunoglobulins and URTI, and no effect of a normal 2-hour training session or carbohydrate ingestion on saliva immunoglobulin concentrations or secretion rates.

Adolescent↗
PubMed2000

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.

Adult↗
PubMed2000

Influence of vitamin C supplementation on cytokine changes following an ultramarathon.

The influence of vitamin C supplementation on the pattern of change in plasma cytokine concentrations was measured in 29 runners following a 90-km ultramarathon. The study was based on a 3 (groups) by 4 (blood samples at 16 prerace, postrace, and 24 h and 48 h postrace) repeated measures design. Groups included placebo control (n = 7) and two groups supplementing vitamin C at 500 mg/day (vit C-500, n = 10) or 1500 mg/day (vit C-1500, n = 12) for 7 days before the race, on race day, and for 2 days after the race. All measured plasma cytokine concentrations were significantly elevated immediately postrace, with the magnitude of increase for tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) much smaller than for IL-6, IL-10, IL-8, and IL-1 receptor antagonist (IL-1RA). Cortisol increased in all groups immediately after the race but significantly less in the vit C-1500 group. Group x time interaction statistics were not significant for any of the plasma cytokines. However, when the placebo and vit C-500 groups were combined (n = 17) and compared with the vit C-1500 group (n = 12), immediate postrace plasma concentrations were significantly lower in the vit C-1500 group for IL-1RA (-57%) and IL-10 (-57%), with a trend measured for IL-6 (-27%, p = 0.11) and IL-8 (-26%, p = 0.14). In summary, runners completing the 90-km Comrades Ultramarathon experienced strong increases in concentrations of plasma IL-6, IL-10, IL-1RA, and IL-8. These increases were attenuated in runners ingesting 1500 mg but not 500 mg vitamin C supplements for 1 week prior to the race and on race day.

Adult↗
PubMed2000

Influence of carbohydrate on cytokine and phagocytic responses to 2 h of rowing.

PURPOSE: This study examined the influence of carbohydrate (C) versus placebo (P) beverage ingestion on the phagocytic and cytokine responses to normal rowing training by 15 elite female rowers. METHODS: Athletes received C or P before, during and after, two, 2-h bouts of rowing performed on consecutive days. Blood was collected before and 5-10 min and 1.5 h after rowing. Metabolic measures indicated that training was performed at moderate intensities, with some high-intensity intervals interspersed throughout the sessions. RESULTS: Concentrations of blood neutrophils and monocytes, phagocytic activity, and plasma IL-1ra were significantly lower postexercise after C versus P ingestion. No differences were observed for oxidative burst activity, IL-6, IL-8, or TNFalpha. Glucose was significantly higher after 2 h of rowing with C ingestion; however, cortisol, growth hormone, epinephrine, norepinephrine, and CRP were not affected by carbohydrate. CONCLUSIONS: These data indicate that carbohydrate compared with placebo ingestion attenuated the moderate rise in blood neutrophils, monocytes, phagocytosis, and plasma IL-1ra concentrations that followed 2-h bouts of training in elite female rowers. No changes in blood hormone concentrations were found.

Adult↗
PubMed2000

Immune function in female elite rowers and non-athletes.

OBJECTIVE: To compare immune function in female rowers and controls in the resting state, and then correlate the results with a two month history of upper respiratory tract infection (URTI). METHODS: Subjects included 20 elite female rowers located at the ARCO Olympic Training Centre in Chula Vista, California, and 19 non-athletic female controls. These two groups were compared cross sectionally for immune function and infection rates. RESULTS: Granulocyte/monocyte phagocytosis, oxidative burst activity, and plasma cytokine concentrations (interleukin-6, tumour necrosis factor-alpha, and interleukin-1 receptor antagonist) did not differ significantly between groups. Phytohaemagglutinin induced lymphocyte proliferative response (adjusted whole blood method) was significantly higher (31% and 36% for optimal and suboptimal concentrations respectively) in rowers than in controls. Natural killer cell activity was substantially higher (1.6-fold for total lytic units) in the female rowers than in controls. Two month health logs disclosed 5.2 (1.2) and 3.3 (1.1) days with URTI symptoms for the rowers and controls respectively (p = 0.268). For all 39 subjects combined, and for the 20 rowers separately, none of the immune parameters correlated significantly with number of days with URTI symptoms. CONCLUSIONS: In this cross sectional comparison of elite female rowers and non-athletes, a group difference was found for natural killer cell activity and phytohaemagglutinin induced proliferative response (whole blood technique), but not other measures of immune function. The number of days with URTI symptoms during the spring season did not differ between groups, and variations in blood measures of immunity were unrelated to URTI.

Adolescent↗
PubMed1999

Effect of carbohydrate ingestion and hormonal responses on ratings of perceived exertion during prolonged cycling and running.

This randomized, double-blind, placebo-controlled study was designed to determine the influence of exercise mode, and 6% carbohydrate (C) versus placebo (P) beverage ingestion, on ratings of perceived exertion (RPE) and hormonal regulation to 2.5 h of high-intensity running and cycling (approximately 75% maximum oxygen uptake) by ten triathletes who acted as their own controls. Statistical significance was set at P < or = 0.05. The pattern of change in RPE over time was significantly different between C and P ingestion (P < 0.001) and between running and cycling modes (P = 0.001). The lowest RPE values were seen in the C-cycling sessions and the highest in the P-running sessions. The pattern of change in the respiratory exchange ratio and fat and carbohydrate oxidation rates were significantly different between the C and P conditions but not between the running and cycling modes. C relative to P ingestion (but not exercise mode) was associated with higher plasma levels of glucose and insulin and lower plasma cortisol and growth hormone levels. The pattern of change in plasma levels of catecholamines and lactate did not differ between the C and P conditions. These data indicate that a lower RPE was associated with a higher level of carbohydrate oxidation, higher plasma glucose and insulin levels, and lower plasma cortisol and growth hormone levels during cycle exercise following C supplementation as compared to P feeding. These findings support a physiological link between RPE and carbohydrate substrate availability as well as selected hormonal regulation during cycle exercise.

Adult↗
PubMed1999

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.

Adult↗
PubMed1999

Immune response to two hours of rowing in elite female rowers.

The influence of carbohydrate (C) versus placebo (P) beverage consumption on the immune and hormonal responses to normal rowing training sessions was measured in 15 elite female rowers residing at the U.S. Olympic Training Center. In a randomized, counterbalanced design, the athletes received C or P beverages (double-blind) before, during, and after two 2-hour bouts of rowing (one day apart). Blood samples were collected before, and 5-10 minutes and 1.5 hours after rowing. Metabolic measures indicated that training was performed at moderate intensities, with some high intensity intervals interspersed throughout the sessions (mean oxygen uptake of 2,307+/-169 m x min(-1), 57% of VO2max). Glucose and insulin were significantly lower after two hours of rowing with ingestion of P compared to C. The patterns of change in cortisol, growth hormone, epinephrine, and norepinephrine did not differ between C and P rowing trials. Blood neutrophil cell counts and the neutrophililymphocyte ratio were significantly higher following P versus C rowing sessions. The patterns of change in blood lymphocyte and lymphocyte subset counts, and lymphocyte proliferative responses did not differ between P and C trials, except for a slight difference in NK cell counts and activity. In summary, minimal changes in blood hormonal and immune measures were found following two-hour bouts of training in elite female rowers. Carbohydrate compared to placebo ingestion attenuated the moderate rise in blood neutrophil counts, but had slight or no effects on other immune parameters.

Adult↗
PubMed1999

Influence of exercise mode and carbohydrate on the immune response to prolonged exercise.

The influence of exercise mode and 6% carbohydrate (C) versus placebo (P) beverage ingestion on lymphocyte proliferation, natural killer cell cytotoxicity (NKCA), Interleukin (IL)-1beta production, and hormonal responses to 2.5 hr of intense running and cycling (approximately 75% VO2max) was measured in 10 triathletes serving as their own controls. The C versus P condition (but not exercise mode) resulted in higher plasma glucose concentrations, lower plasma cortisol concentrations, reduced postexercise lymphocytosis and NKCA, and a lessened T-cell reduction during recovery, No condition or mode effects were observed for concanavalin A and phytohemagglutinin-induced lymphocyte proliferation. Significant mode (but not condition) effects were observed for lipopolysaccharide-induced IL-1beta production over time. However, when expressed per monocyte, the mode effect was abolished and a sustained suppression in IL-1beta/monocyte was observed in all sessions throughout recovery. These data indicate that carbohydrate ingestion significantly affects plasma glucose and cortisol concentrations, blood lymphocyte counts, and NKCA, whereas exercise mode has no effect on these parameters.

Adult↗
PubMed1998

Carbohydrate supplementation and the lymphocyte proliferative response to long endurance running.

This randomized, double-blind, placebo-controlled study examined the influence of 6% carbohydrate ingestion on hormonal and lymphocyte proliferative responses (5 total samples over 9 hours) to 2.5 h of high-intensity running by 30 experienced marathon runners. The T-cell response differed between groups, with the placebo group exhibiting a greater increase immediately post-run and greater decrease at 3 h of recovery. No group differences were observed for Con A-, PHA-, or PWM-induced lymphocyte proliferation. However, when PHA was adjusted per T-cell, group differences were observed, highlighted by a decrease in the placebo group immediately post-run. Glucose and cortisol responses differed between groups, with glucose lower and cortisol higher in the placebo group immediately post-run. Post-run glucose correlated negatively with postrun cortisol (r=-0.670, P< 0.001) and epinephrine (r=-0.540, P=0.002). Post-run cortisol also correlated negatively with total lymphocytes and T-cells at 1.5 hours (r=-0.429, P=0.018 and r=-0.424, P=0.019, respectively) and 3 hours (r=-0.566, P=0.001 and r=-0.523, P=0.003, respectively) of recovery. The pre- to post-run change in glucose correlated to the same changes in PHA/T-cell (r=0.456, P=0.011). The data support an interactive effect of carbohydrate ingestion on plasma glucose and cortisol. The data support an interactive effect of carbohydrate ingestion on plasma glucose and cortisol, T-cell trafficking, and cell-adjusted PHA-induced lymphocyte proliferation following long endurance running.

Adult↗
PubMed1998

Influence of mode and carbohydrate on the cytokine response to heavy exertion.

OBJECTIVE AND METHODS: This randomized, double-blind, placebo-controlled study was designed to determine the influence of exercise mode and 6% carbohydrate (C) versus placebo (P) beverage ingestion, on blood cell counts, plasma glucose, hormone, and inflammatory cytokine responses (five total samples over 9 h) to 2.5 h of high-intensity running and cycling (approximately 75% VO2max) by 10 triathletes who acted as their own controls. Statistical significance was set at P < or = 0.05. RESULTS: C relative to P ingestion (but not exercise mode) was associated with higher plasma levels of glucose and insulin, lower plasma cortisol and growth hormone, and diminished perturbation in blood immune cell counts. The pattern of change over time for interleukin (IL)-6 was significantly different between C and P conditions (P = 0.021) and between running and cycling modes (P < 0.001), with the lowest postexercise values seen in the C-cycling sessions (10.7 +/- 1.8 pg x mL(-1)) and the highest in the P-running sessions (51.6 +/- 14.2 pg x mL(-1)). The pattern of change over time between C and P conditions (but not modes) was significantly different for IL-1 receptor antagonist (P = 0.003), with values once again lowest for the C-cycling sessions (1.5 h postexercise, 301 +/- 114 pg x mL(-1)) and highest for the P-running sessions (1171 +/- 439 pg x mL(-1)). CONCLUSION: These data indicate that carbohydrate versus placebo ingestion (4 mL x kg(-1) carbohydrate or placebo every 15 min of the 2.5-h exercise bout) is associated with higher plasma glucose levels, an attenuated cortisol response, and a diminished pro- and anti-inflammatory cytokine response.

Adult↗