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Biomedical subjects

M G Flynn

Publications and source records attributed to M G Flynn.

At least 19 recordsLinked to original sources
PubMed2006

Exercise during late-follicular menstrual phase: influence on immune parameters.

AIM: The purpose of this study was to examine whether training status and plasma hormones (estradiol--E2, progesterone--P, luteinizing hormone--LH, and follicle-stimulating hormone--FSH) have an effect on selected immune indexes during or following an acute bout of exercise. METHODS: Seven female triathletes (TRI) and 7 recreationally active (REC) females were randomly assigned to rest (RE) and exercise (EX) trials during the late-follicular menstrual phase (LF). The EX was 1 hour of cycling at 63.1+/-6% VO2peak (TRI) and 61+/-5.1% VO2peak (REC) and RE was 1 hour of sitting. Blood was drawn for both trials at baseline (0H), 1 hour (1H), and at 3 hours (3H). RESULTS: Positive correlations were found between E2 and CD19+ cells for both groups as well as P and CD8+ cells for the REC group. E2 increased during EX and returned to baseline at 3HEX for both groups, however, LH remained elevated at 3HEX for REC. There were significant exercise time effects for CD3+, CD4+, CD8+, and CD3- CD16+ CD56+ cells. The NCMC and 1:1 were elevated at 1HEX for both groups and returned to baseline by 3HEX. During RE, CD3- CD16+ CD56+ cell numbers for both groups and NCMC for REC remained elevated at 3HRE. CONCLUSIONS: E2 and P correlated with CD19+ and CD8+ cells, respectively. Although there were transient exercise-induced changes in immune indexes and E2 and LH, with LH remaining elevated at 3HEX for REC, both training groups elicited similar responses for plasma hormones, lymphocyte subpopulations, and NCMC.

Adult↗
PubMed2005

The effects of chondroitin sulfate supplementation on indices of muscle damage induced by eccentric arm exercise.

AIM: Delayed onset of muscle soreness (DOMS) often results from unaccustomed exercise or exercise that involves heavy eccentric loading of skeletal muscle. Chondroitin sulfate (CS) has been reported to possess anti-inflammatory and analgesic properties and has been used widely in the treatment of osteoarthritis. Based on these findings, the investigators sought to determine whether CS supplementation might reduce DOMS symptoms associated with eccentric arm exercise. METHODS: Sixteen non-resistance-trained males participated in a double-blind protocol. Subjects consumed 3,600 mg x day-1 of encapsulated CS or placebo for 14 days preceding the exercise protocol and during 48 hours of follow-up measurements. Subjects performed a maximum of 50 eccentric contractions of the elbow flexors against a resistance that was 120% of the concentric one-repetition maximum. RESULTS: Significant time effects were present for soreness, relaxed elbow extension (joint angle), and creatine kinase; all measures were significantly altered 48 hours after the exercise session. No effects were present for complement system fragment C3a and prostaglandin E2. No significant treatment or interaction effects were detected for any of the variables. CONCLUSIONS: CS supplementation was not found to be effective in the prevention of DOMS, nor did it influence biochemical indices of inflammation and muscle damage following heavy eccentric loading of the arm flexors.

Adult↗
PubMed2003

Influence of iron status and iron supplements on natural killer cell activity in trained women runners.

Twenty-two trained women runners (.VO2peak 48.1 + 1.2 ml x kg -1 x min -1) were divided into an iron supplement (n = 13) or placebo group (n = 9) based on initial serum ferritin concentration (24.2 +/- 2.9 and 58.5 +/- 4.0 microg x l -1, respectively). Exercise consisted of a 35-min run (80 % .VO2peak) and was performed at week 0 (WK0), after two weeks of intensified training (WK2) and after eight weeks recovery training (WK10). The eight weeks recovery training were concomitant with subjects taking iron supplements or placebo in a double blind fashion. Concentrations of serum ferritin, serum iron and total iron binding capacity were assessed pre-exercise and complete blood count, natural killer cell activity (NKACT), and cell surface markers for CD3+, CD4+, CD3+,CD8+, CD3-, CD16+, CD56+ cells were determined both pre- and post-exercise. Serum ferritin concentrations were significantly (p < 0.05) increased on WK10 compared to WK2 (time effect). NKACT (%lysis) and NK cell number was lower (p < 0.05) at WK0 for supplement (42.9 +/- 1.9 % and 305.5 +/- 15.0 x 10 6 x l -1, respectively) compared to placebo groups (50.9 +/- 2.0 and 406.1 +/- 25.6, respectively). Two weeks of intensified training did not alter indices of host defense. In conclusion, NKACT and NK cell numbers were lower in subjects with greater body mass and lower iron stores (p < 0.05), but were not significantly altered after two weeks of intensified training or when serum ferritin levels increased.

Adaptation, Physiological↗
PubMed2000

Influence of acute submaximal exercise on T-lymphocyte suppressor cell function in healthy young men.

A defect in T-lymphocyte suppressor cell function has been reported to occur in a number of autoimmune diseases. The influence of exercise on suppressor cell function has not been determined in individuals with autoimmune diseases, nor has it been determined in healthy individuals. The purpose of this investigation was to determine the effect of an acute bout of submaximal exercise on suppressor cell function in healthy males. Each subject (n = 10) completed an exercise trial (E; 1 h of cycle ergometry at 70.6% of maximal oxygen uptake, followed by 2 h of recovery) and a resting trial (R; 3 h of seated rest), separated by at least 1 week. Treatment (E or R) order was counterbalanced. Venous blood samples were obtained pre-exercise (PRE), immediately after exercise (POST), and 2 h post-exercise (2HPOST), and at the same time points in the R trial. Lymphocyte phenotype percentages were determined by flow cytometry, while concanavalin-A-induced suppressor cell function was determined on peripheral blood mononuclear cells. No change was observed in the percentage of T-cytotoxic/suppressor cells. Suppressor cell function was significantly different between treatments, with the POST E value [mean (SD) 56.8 (1.6)%] being higher than the POST R value [41.7 (1.9)%]. No significant difference was observed 2HPOST. In conclusion, acute submaximal exercise resulted in a transient increase in suppressor cell function in healthy males.

Adult↗
PubMed2000

Attitudes and perceptions of fitness professionals regarding obesity.

The purpose of this study was to assess perceptions of exercise professionals regarding obesity. A three page, 25-item survey was mailed to a random sample of 500 certified Health Fitness Instructors, Exercise Test Technologists, and Exercise Specialists from a certification list provided by the American (College of Sports Medicine (ACSM). The return rate was 66%. Most exercise professionals (74%) supervised or worked directly with obese clients in an exercise/fitness setting. The majority of exercise professionals believed that normal weight is very important to a person's health, that physical activity is very important in the treatment of obesity, that they should be role models by maintaining normal weight, that they are obligated to counsel obese persons concerning the health risks of obesity, that they are very competent to prescribe exercise programs for weight loss, and that counseling obese persons on exercise for weight loss is professionally gratifying. The majority of exercise professionals also believed sedentary lifestyles, poor eating behavior, excessive calorie consumption, and psychological problems play a major role in most obesity. Exercise professionals reported that they received most of their information on weight control from textbooks, college classes, scientific journals, workshops/seminars, and past experience.

Adult↗
PubMed2000

Iron status and resting immune function in female collegiate swimmers.

Iron deficiency may lead to anemia and may result in compromised endurance exercise performance. Iron deficiency has also been reported to adversely affect the immune system and has been associated with attenuation of natural killer cell (NK) activity. This study was conducted to examine the relationship between iron status and NK activity in highly conditioned female athletes. Ten collegiate female swimmers (SWM) and 9 inactive females (SED) participated in this investigation. Resting blood samples were obtained and analyzed for serum iron and ferritin. NK activity (% lysis) was determined using a whole blood method (51Cr release assay). No significant relationship was found between iron and NK activity (r = 0.55, p =.09), nor between serum ferritin and NK activity (r = 0.33, p =.35) for SWM. ANOVA revealed significantly greater NK activity for SWM (51.63 +/- 15.79%) versus SED (30.34 +/- 13.67%). Serum ferritin levels were not significantly different between SWM (20.38 +/- 8.62 hg á ml-1) and SED (16.79 +/- 10.53 hg á ml-1), nor were iron values different between groups (16.54 +/- 2. 17 mmol á L-1 SWM; 11.92 +/- 2.61 mmol á L-1 SED). A significant relationship between iron status and resting immune function could not be established. Exercise training may affect NK activity; however, the influence of iron status on immune function requires further evaluation.

Adult↗
PubMed2000

Effects of hormone replacement therapy on selected indices of immune function in postmenopausal women.

The purpose of this study was to examine the effects of long-term hormone replacement therapy (HRT) on selected indices of resting immune function in postmenopausal women. Postmenopausal women aged 54-66 were divided into two groups, those taking HRT (n = 17) and controls (n = 19). Blood samples were obtained and analyzed for mononuclear cell numbers, lymphocyte proliferation (LP) and natural cell-mediated cytotoxicity (NCMC). There were no significant differences between groups for mononuclear cell numbers. LP was significantly higher for HRT, while NCMC was significantly lower for HRT. HRT is currently being prescribed to postmenopausal women for prevention of a variety of medical conditions including osteoporosis, cardiovascular disease, stroke, and Alzheimer's disease yet HRT is often associated with altered immune parameters. In this study, women taking HRT had increased lymphocyte blastogenesis and decreased NCMC compared to controls.

Cytotoxicity, Immunologic↗
PubMed1999

Effects of intensified training and detraining on testicular function.

OBJECTIVE: To examine the effects of an increased training load and period of detraining on testicular function in male distance runners. DESIGN: Multiple-group time-series design using a control group. SETTING: University of Toledo and Toledo Hospital. PARTICIPANTS: Eight male runners and eight age-matched sedentary control subjects. Subjects were considered fit for participation after a physical and genital examination conducted by a physician. INTERVENTION: Subjects provided blood and semen samples every 2 weeks for 8 weeks. The training regimen for the runners consisted of 2 weeks at normal training (NT), 2 weeks at 143% of NT (IT1), 2 weeks at 186% of NT (IT2), and 2 weeks at 50% of NT (RT). These percentages represent increases in training distance (volume). MAIN OUTCOME MEASURES: Within the context of this investigation, the following hypothesis was developed: increases or decreases in training would not significantly alter sperm count, density, motility, or morphology, or concentrations of reproductive hormones or cortisol in runners. RESULTS: There were no statistically significant differences observed between runners and control subjects for any of the reproductive hormones or cortisol. In addition, there was no significant treatment effect for sperm count, motility, or morphology. The sperm levels in two runners in this investigation dropped to oligospermatic levels after IT2; however, total sperm count increased in both runners after 2 weeks of RT. CONCLUSION: Four weeks of increased training and 2 weeks of reduced training did not significantly affect the subjects in this investigation. It is possible that a particular level or degree of training must be surpassed before any clinical alterations are evident. Future longitudinal studies are necessary to identify the extent to which endurance training may alter reproductive hormones and testicular function.

Adult↗
PubMed1999

Effects of resistance training on selected indexes of immune function in elderly women.

Women aged 67-84 yr were randomly assigned to either resistance exercise (RE, n = 15) or control group (C, n = 14). RE group completed 10 wk of resistance training, whereas C group maintained normal activity. Blood samples were obtained from the RE group (at the same time points as for resting C) at rest, immediately after resistance exercise, and 2 h after exercise before (week 0) and after (week 10) training. Mononuclear cell (CD3+, CD3+CD4+, CD3+CD8+, CD19+, and CD3-CD16+CD56+) number, lymphocyte proliferative (LP) response to mitogen, natural cell-mediated cytotoxicity (NCMC), and serum cortisol levels were determined. Strength increased significantly in RE subjects (%change 8-repetition maximum = 148%). No significant group, exercise time, or training effects were found for CD3+, CD3+CD4+, or CD3+CD8+ cells, but there was a significant exercise time effect for CD3-CD16+CD56+ cells. LP response was not different between groups, across exercise time, or after training. NCMC was increased immediately after exercise for RE subjects at week 0 and for RE and C groups at week 10. The week 0 and week 10 NCMC values were above baseline for both RE and C groups 2 h after exercise. In conclusion, acute resistance exercise did not result in postexercise suppression of NCMC or LP, and 10 wk of resistance training did not influence resting immune measures in women aged 67-84 yr.

Aged↗
PubMed1999

Indomethacin does not influence natural cell-mediated cytotoxic response to endurance exercise.

Natural cell-mediated cytotoxicity (NCMC) has been shown to be attenuated during recovery from high-intensity or prolonged exercise. Two theories have been proposed to explain the transient suppression of NCMC: prostaglandin-induced inhibition of natural killer (NK) cell activity or a numerical redistribution of NK cells. This study was designed to examine the effects of oral indomethacin (a prostaglandin inhibitor) on NCMC before and after 1 h of high-intensity running (85% maximal oxygen uptake). A secondary purpose was to compare whole blood and isolated peripheral blood mononuclear cell assay procedures for assessing NCMC. Ten male distance runners completed two trials that were preceded by either 48 h of indomethacin (Indo; 150 mg/day) or no treatment (control). NK (CD3(-)/CD16(+)/CD56(+)) cell concentrations were significantly elevated postexercise but were not affected by Indo. NCMC was significantly suppressed at 1.5 h of recovery relative to preexercise only with the whole blood assay procedure. Indo was not found to influence NCMC, leukocyte, or lymphocyte subset concentrations. Mean cytotoxic response was significantly greater with the whole blood method.

Adult↗
PubMed1999

The effects of swimming and running on energy intake during 2 hours of recovery.

OBJECTIVE: To determine energy intake in the 2 hrs after swimming (S) and running (R) at the same relative exercise intensity and duration (71.8 +/- 2.5% VO2max; 45 min) to evaluate whether a difference in recovery energy intake could explain the greater body fat observed in swimmers relative to runners. METHODS EXPERIMENTAL DESIGN: this was a randomized crossover design. SETTING: running exercise was conducted on a motorized treadmill (Quinton) while swimming was conducted in a 45.7 m pool. PARTICIPANTS: eight well-trained competitive male triathletes participated in this investigation. INTERVENTIONS: subjects were blinded to the purpose of the study and swam and ran on separate occasions for 45 min at 71.8 +/- 2.5% of VO2max. Subjects were then placed in a room with a variety of foods and beverages for 2 hrs after R and S. MEASURES: energy intake (kJ/2 hrs and kcal/2 hrs) was determined by weighing and measuring the food remaining in the room after 2 hrs of postexercise recovery. Expired gases, heart rates, and Ratings of Perceived Exertion were obtained at 15 min intervals throughout exercise. Blood samples for serum glucose and lactate were obtained preexercise and immediately, 15 min, and 135 min postexercise. Perceived hunger and thirst ratings were obtained after the subjects were seated in the room containing the food. RESULTS: Serum glucose was significantly (p < or = 0.05) higher after R compared to S immediately after exercise (5.4 +/- 0.3 mmol/L for R and 4.2 +/- 0.1 mmol/L for S) but no significant differences were observed for hunger using a five point Likert scale (3.3 +/- 0.3 for R and 3.4 +/- 0.3 for S), energy intake (4584 +/- 611 kJ/2 hrs; 1095 +/- 146 kcal/2 hrs for R and 4383 +/- 484 kJ/2 hrs; 1047 +/- 116 kcal for S) or blood lactate. CONCLUSION: The type of exercise, swimming or running, did not significantly influence energy intake during 2 hours of postexercise recovery.

Adult↗
PubMed1998

Cross training: indices of training stress and performance.

Twenty well-trained runners (VO2max 4.6+/-0.5 L x min[-1]) were age and ability matched and assigned to either a cross training (CT) or run only group (RT). All subjects maintained normal running distance and intensity for 6 wk and reported for three additional training sessions per week. These workouts were performed outdoors on a 400-m track or measured road course (RT) or on a bicycle ergometer (CT). The sessions were as follows: (work x rest(-1) ratio = 1): 5 x 5 min at >95% VO2max/peak (Monday), 50-60 min at 70% VO2max/peak (Wednesday), and 3 x 2.5 min at >105% VO2max/peak, plus 6 x 1.25 min at >115% VO2max/peak (Friday). Subjects were tested before (PRE), after 3 wk (MID), and after 6 wk (POST) of intensified training. Blood samples were obtained from RT, CT, and ten controls (CON) at each time point (0600 h). Runners also completed a 10-min submaximal run at the same absolute intensity (velocity to elicit 75% of initial V02max) during which heart rate, RPE, and VO2 were measured. Each runner then completed a simulated 5-km race (time trial) on a treadmill. Total testosterone (TT), free testosterone (FT), cortisol (C), and creatine kinase activity (CK) were determined. Running economy was similar between RT and CT; however, RPE decreased significantly at MID and POST compared with that at PRE (P < 0.05; time effect). There were no significant differences among groups for TT, FT, or CK, but C was significantly lower in CON than in RT and CT. Performance was significantly faster (P < 0.05; time effect) in the 5-km race at MID (1076.1+/-81.4 s) and POST (1068.6+/-83.9) compared with PRE (1096.6+/-79.5) but was not different between CT and RT. In conclusion, RT and CT responded similarly to 6 wk of increased training, and both groups improved 5-km performance to a similar extent.

Adult↗
PubMed1997

Hormonal responses to excessive training: influence of cross training.

The purpose of this investigation was to examine the changes in blood hormone levels elicited by increases in training volume. After 30 d of recording their training volume and intensity (normal training, 57.5 +/- 10.9 km.wk-1), 11 well-trained distance runners completed two randomly assigned 10 day periods of increased training volume (200% normal training). Each increased training regimen was preceded by two weeks of reduced training (80% normal training). The increased training regimens consisted of either running only (RT) at 200% of normal training distance or running (100% normal training) and cycling (kcal = 100% normal training: CT). During each increased training regimen the subjects ran 10 consecutive afternoons at a distance equivalent to 100% of normal training (approximately 75% VO2max) and performed eight additional morning sessions (0500-0800 h). During RT the subjects performed their morning workouts on a treadmill and during CT the workouts were performed on a bicycle ergometer. Blood samples were obtained (0500-0700 h) after 15 min supine rest after normal training, and before (day 0), on day five (day 5) and following ten days (day 11) of RT and CT. Serum was analyzed for testosterone, free testosterone, cortisol, adrenocorticotropic hormone, luteinizing hormone, and dehydroepiandrosterone sulfate. Free testosterone was significantly (p < 0.05) reduced on day 5 and day 11 of RT and CT compared to day 0 and total testosterone was lower on day 5 than day 0. However, no significant treatment or interaction effects were observed for total testosterone or free testosterone. Dehydroepiandrosterone sulfate was also significantly lower across time, i.e., day 11 was lower than day 0 and day 5; however, cortisol, adrenocorticotropic hormone, and luteinizing hormone were not significantly altered during RT or CT. The endocrine responses to an increased training volume with cross training and mode specific training were similar.

Adrenocorticotropic Hormone↗
PubMed1997

Serum haptoglobin and ferritin during a competitive running and swimming season.

The purpose of the study was to examine ferritin, haptoglobin, and red cell indices during a competitive running and swimming season. Male runners (N = 8) and swimmers (N = 5) were tested four times during their respective seasons. The runners were tested before the start of organized practice (RT1), after 3 wk of increased training (RT2), 3 wk prior to the conference championship (pre-taper, RT3), and 3 d after the conference championship (post-taper, RT4). The swimmers were tested after the first 9 wk of training (ST1), after completing 2 wk of hard training (ST2), after an additional 6wk of training (pre-taper, ST3), and 1 wk following the conference championship (post-taper, ST4). For the runners, hemoglobin, hematocrit, and red blood cell number were lower (p < 0.05) at RT2 and were not accompanied by significant changes in other red cell indices or haptoglobin. Serum ferritin in the runners was lower at RT3 and RT4 compared to RT1 despite an adequate dietary iron intake. Hemoglobin and mean cell hemoglobin concentration were lower and mean cell volume was higher in the swimmers at ST3 and ST4. No significant changes were observed in other red cell indices for swimmers; however, serum haptoglobin tended (p = 0.07) to be reduced at ST2. In conclusion, collegiate male runners and swimmers do not demonstrate clinical hypoferritinemia, hypohaptoglobinemia, or alterations in red cell indices suggestive of the early stage of anemia with or without iron deficiency during their respective season.

Anemia↗
PubMed1997

Effect of 4 wk of deep water run training on running performance.

The purpose of this study was to determine whether trained competitive runners could maintain on-land running performance using 4 wk of deep water run training instead of on-land training. Eleven well-trained competitive runners (10 males, 1 female; ages, 32.5 +/- 5.4 yr; height, 179.8 +/- 9.3 cm; weight, 70.4 +/- 6.7 kg (mean +/- SD)) trained exclusively using deep water run training for 4 wk. Subjects trained 5-6 d.wk-1 for a total of 20-24 sessions (mean +/- SD, 22 +/- 1.5 sessions). Instruction and practice sessions were conducted prior to the training period. Before and after the deep water run training, subjects completed a 5-km race on the treadmill using a computer based system, a submaximal run at the same absolute workload to assess running economy, and a combined lactate threshold and maximal oxygen consumption test. No significant differences were found for (mean +/- SEM): 5-km run time (pre, 1142.7 +/- 39.5 s; post, 1149.8 +/- 36.9 s; P = 0.28), submaximal oxygen consumption (pre 44.8 +/- 1.2 mL.kg-1.min-1; post, 45.3 +/- 1.5 mL.kg-1.min-1; P = 0.47), lactate threshold running velocity (pre, 249.1 +/- 0.9 m.min-1; post, 253.6 +/- 6.3 m.min-1; P = 0.44), or maximal oxygen consumption (pre, 63.4 +/- 1.3 mL.kg-1.min-1; post, 62.2 +/- 1.3 mL.kg-1.min-1; P = 0.11). Also no differences were found among Global Mood State pre-training, each week during training, and post-training. Competitive distance runners maintained running performance using 4 wk of deep water run training as a replacement for on-land training.

Adult↗
PubMed1995

Run training vs cross training: influence of increased training on running economy, foot impact shock and run performance.

The purpose of the study was to compare changes in running economy, foot impact shock, run performance, and resting heart rate and blood pressure elicited by increases in training volume via run training (RT) and cross training (CT). After 30 d of normal training (NT), male runners (N = 11) completed two 10 d periods of increased training each preceded by 14 d of reduced training (80% NT). Subjects ran 10 consecutive days in the afternoon (100% of NT) and performed 8 additional workouts in the morning (100% of NT). The morning sessions were performed on a cycle ergometer (CT) or a treadmill (RT). Running economy, foot impact shock and lactate were assessed during submaximal running (3.9 +/- 0.06 m.sec-1) at D0 and D11. Following the submaximal run, subjects completed a simulated 5 km race on a treadmill. VO2 during the running economy test was significantly higher at D11 of CT (52.5 +/- 1.5) compared to RT (51.1 +/- 1.4 ml.kg-1.min-1). RER, carbohydrate oxidation, and lactate were significantly lower; whereas, foot impact shock was significantly higher following both training modes. No significant changes in run performance, resting heart rate and blood pressure occurred during the study. In summary, 10 d of increased training resulted in a reduced running economy for CT, and a lower carbohydrate oxidation and an increase in foot impact shock for both training modes.

Adult↗
PubMed1995

A carbohydrate loading regimen improves high intensity, short duration exercise performance.

This investigation examined the effect of a carbohydrate loading regimen on high intensity, short duration run performance. Using a random crossover design, 8 trained runners completed a 15-min submaximal run and a performance run to exhaustion after two dietary treatments. The mixed diet (MD) contained 4.0 +/- 0.5 g.kg-1.d-1 of carbohydrate (CHO) for 6 days. The experimental diet (HCD) contained 4.5 +/- 0.5 g CHO.kg-1.d-1 for 3 days followed by 8.2 +/- 0.4 g CHO kg-1.d-1 for 3 days. Training consisted of daily runs of 90, 40, 40, 20, and 20 min at approximately 75% of VO2max. Day 6 was a rest day, and testing was completed on Day 7. Preexercise lactate, body weight, submaximal VO2, and heart rate did not differ significantly between treatments. Carbohydrate oxidation during submaximal running was higher (p < 0.05) after HCD than after MD. Time to exhaustion in the performance run was longer after HCD compared to MD. Results indicate that a carbohydrate loading regimen increases CHO oxidation during submaximal exercise and improves high intensity, short duration run performance.

Adult↗