Aerobic training does not alter CRP in apparently healthy, untrained men.

AIM: Regular aerobic exercise may reduce cardiovascular disease (CVD) risk by lowering the concentration of inflammatory markers, such as C-reactive protein (CRP). While studies in diseased populations have shown significant decreases in CRP concentrations with regular aerobic training, little has been conclusively determined regarding the effects of aerobic training on CRP concentrations in apparently healthy, untrained populations. Aim of the study was to examine the effects of a 17-wk half marathon training program (TP) on CRP concentrations, aerobic fitness, and body composition in apparently healthy, untrained men. METHODS: Twenty men (29.3±1.0 y) enrolled as training subjects (TRN) in a 17-wk half marathon TP. An additional 22 men (27.8±1.4 y) served as controls (CON). Fasting blood samples were taken at four time points over the TP and were analyzed for CRP and interleukin-6 (IL-6) concentrations. Aerobic capacity (VO2max) and body fat percent (BF%) were measured before and after the TP. RESULTS: No significant post-training changes in CRP (P=0.70) or IL-6 concentrations (P=0.67) were seen in TRN as a result of the TP, despite significant improvements in VO2max (42.2±1.9 ml∙kg-1∙min⁻¹, P<0.0001) and significant reductions in resting heart rate (P=0.004), BF% (P=0.03), and body mass index (BMI, P=0.05). No significant changes in CRP, VO2max, BMI, or BF% were detected in CON over time. CONCLUSION: Regular aerobic training does not appear to affect CRP concentrations in apparently healthy, untrained men despite significant improvements in bodyweight, BF%, BMI, and VO2max.

Relation between anthropometric measures of fat distribution and cardiovascular risk factors in overweight pre- and postmenopausal women.

This study compared three different measures of central adiposity: waist-to-hip ratio (WHR), waist-to-height ratio (WSHT), and waist circumference with cardiovascular risk factors, including serum lipoproteins and blood pressure in overweight pre- (n = 115) and postmenopausal (n = 46) women. Premenopausal women had a mean age of 35.6 +/- 6.79 y and a mean body mass index (BMI; in kg/m2) of 37.08 +/- 6.01. Postmenopausal women had a mean age of 52.5 +/- 8.19 y and a mean BMI of 38.75 +/- 6.9. Although several correlations between central adiposity and serum lipoproteins and blood pressure were significant, they were unaffected by menopausal status. There were also no significant differences among the three measures of central adiposity in relation to cardiovascular risk factors within premenopausal and postmenopausal groups. An analysis of covariance controlling for BMI showed that after stratifying WSHT into tertiles, a significant interaction of WSHT group by menopausal status was found for systolic blood pressure (SBP) (P = 0.019). Postmenopausal women had a significantly greater SBP than premenopausal women in the lowest and highest tertiles (P = 0.001); however, this pattern was not shown in the middle WSHT tertile. The relation between central adiposity and cardiovascular risk factors appears to be unchanged after menopause, except when WSHT is used to indicate SBP. Because increased central adiposity may also indicate an increase in cardiovascular risk factors, measurements of central adiposity can be used to supplement the routine clinical evaluation of cardiovascular risk factors in both pre- and postmenopausal overweight women.

A constant-load ergometer for measuring peak power output and fatigue.

A constant-load cycle ergometer was constructed that allows maximal power output to be measured for each one-half pedal revolution during brief, high-intensity exercise. To determine frictional force, an electronic load cell was attached to the resistance strap and the ergometer frame. Dead weights were attached to the strap's free end. Flywheel velocity was recorded by means of a magnetic switch and two magnets placed on the pedal sprocket. Pedaling resulted in magnetically activated switch closures, which produced two electronic pulses per pedal revolution. Pulses and load cell output were recorded (512 Hz), digitized, and stored on disk via microcomputer. Power output was later computed for each pair of adjacent pulses, representing average power per one-half pedal revolution. Power curves generated for each subject were analyzed for peak power output (the highest one-half pedal revolution average), time to peak power, power fatigue rate and index, average power, and total work. Thirty-eight males performed two 15-s tests separated by 15 min (n = 16) or 48 h (n = 22). Peak power output ranged from 846.0 to 1,289.1 W. Intraclass correlation analysis revealed high test-retest reliability for all parameters recorded on the same or different days (R = 0.91-0.97). No significant differences (P greater than 0.05) were noted between parameter means of the first and second tests. These results indicate that the ergometer described provides a means for conveniently and reliably assessing short-term power output and fatigue.

Effects of acute inhalation of the bronchodilator, albuterol, on power output.

This study was designed to examine the effects of acute inhalation of the bronchodilator, albuterol (Proventil, Schering Corp.), on high intensity power output. Fifteen healthy nonasthmatic subjects (eight male, seven female, 18-33 yr) performed four supramaximal 15-s rides on a bicycle ergometer. Rides were arranged in pairs with a 10-min rest interval. Each pair of rides was preceded by a 5-min warm-up. Sessions were separated by a minimum of 48 h. The study design was fully randomized and double blind. Ten minutes prior to each pair of rides subjects inhaled two metered doses (180 micrograms) of albuterol (A) or a placebo (P). Individual ANOVAs revealed a significant difference between the A and P treatment for peak power (A = 886.6 W, P = 858.3 W) and fatigue (A = 27.2%, P = 24.4%). Mean changes in FEF25-75% (A = 0.712, P = 0.040 l.s-1), FEV1.0 (A = 0.188, P = 0.007 l), and PEF (A = 0.573, P = -0.155 l.s-1) were also statistically significant; however, these changes did not correlate to the anaerobic performance changes. No significant differences were found between treatments for heart rate increases resulting from the power test (A = 56.73 bpm, P = 53.20 bpm). These results indicate an ergogenic effect of the bronchodilator on short-term power output independent of impact on respiratory smooth muscle, with no effect on cardiac response.

Physical and psychological changes with vigorous exercise in sedentary primigravidae.

PURPOSE: The present study examined the effects of exercise on physical and psychological variables in sedentary primigravidae (PRA). METHODS: A total of nine women randomly assigned to an exercise (E) (mean age = 31.3 +/- 3.1 yr) and six subjects randomly assigned to a control (C) group (mean age = 27.8 +/- 3.1 yr) fulfilled all requirements for the study. Exercise included a variety of exercise activities performed to a target heart rate of 150-156 beats x min(-1), three times per week for 15 wk. RESULTS: Results showed no significant differences between E and C groups in physical characteristics initially. A repeated measures ANOVA showed a significant group effect (P < 0.05) and a significant group by time interaction (P = 0.001) with the E group showing a significantly longer amount of time on the PWC150 test than the C group. There was no significant group, time, or group by time interaction for lactate accumulation. This occurred, despite the fact that the E group spent 56% longer on the PWC150 test and the C group spent 30% less time on the same test at the conclusion of the study. Finally, the E group in comparison to the C group showed more favorable improvements in several items related to health and well-being on the Body Cathexis Scale. There were no significant differences between E and C groups in any pregnancy outcome measures. All babies were delivered healthy at term. CONCLUSIONS: These data suggest that a vigorous exercise program can lead to significant improvements in aerobic fitness at similar lactate concentrations compared to a control group and can be well tolerated by low risk sedentary PRA without any deleterious effects occurring to herself or unborn child.

The effects of albuterol and isokinetic exercise on the quadriceps muscle group.

Subjects performed 9 wk of isokinetic knee extensions twice weekly. Albuterol (N = 13) or placebo (N = 9) was administered for 6 wk; groups received 16 mg.d-1 of either treatment. Training consisted of three sets of 10 repetitions at 45 degrees.s-1. Data were collected at weeks 0, 6, and 9. Concentric and eccentric variables examined included: peak torque (CPT, EPT), total work (CTW, ETW), average power (CAP, EAP), time to peak torque (CTTPT, ETTPT), peak torque to body weight ratio (CPT/BW), and work to body weight ratio (CW/BW, EW/BW). Other variables included: thigh circumference (CIRC), thigh cross-sectional area (CSA), forced vital capacity (FVC), and forced expiratory volume (FEV1), MANOVA and the Dunn-Bonferroni post-hoc found differences within groups for CPT, CTW, CAP, CPR/BW, EPT, ETTPT, and CSA. Interactions were noted for CW/BW, ETW, EAP, EPT/BW, and ETW/BW; with persons administered albuterol yielding superior values. CW/BW, ETW, and EAP showed interactions at post-testing, while EPT/BW and EW/BW interacted at both midtesting and post-testing. Results indicate therapeutic doses of albuterol administered with resistance exercise may augment strength gains.

Effects of partial occlusion of circulation on frequency and amplitude of surface electromyography.

We examined two distinct questions. First, would the amplitude and frequency changes characteristic of fatigue produced by an isometric exercise be produced by fatiguing isotonic exercise? Second, are the frequency shifts produced during fatiguing exercise the result of increased metabolite concentration? Ten subjects (five men and five women, aged 22-43 years) performed two sets of 25 biceps curls at between 50 and 60% of their maximal voluntary contraction (MVC). One set was performed with the circulation to the arm unimpaired (NO); during the other set, a blood pressure (BP) cuff held midway between systolic and diastolic pressure was used to partially occlude (PO) circulation. Both the NO and PO conditions produced significant changes in root mean square (rmsEMG) of the amplitude and the mean power frequency (MPF) of the signal. Both the increase in amplitude and the downward shift in MPF of the frequency power spectrum characteristic of fatigue were significantly greater for the PO versus NO condition (PO = 29.47 Hz, NO = 7.39 Hz). These results indicate that the changes in amplitude and frequency characteristic of fatigue observed during isometric exercise can be produced to a lesser degree during dynamic exercise. In addition, these changes can be amplified by addition of occlusion caused by external compression. Because the compressive force used for occlusion allowed blood flow into the working muscle while impairing venous return, this degree of change appears to be directly related to reduced metabolite washout.

The effect of knee and foot position on the electromyographical activity of the superficial quadriceps.

Isometric quadriceps exercises are used early in knee rehabilitation. Varying knee or foot position is hypothesized to selectively activate specific quadriceps muscles. This study examined the activities of the vastus medialis oblique, vastus lateralis, and rectus femoris during isometric contractions at 90 degrees, 150 degrees, and 175 degrees knee angles with internally rotated, neutral, and externally rotated foot positions. Subjects performed three perceived maximal isometric contractions at each knee angle/foot position while electromyographic activity (EMG) was collected. Statistical analysis consisted of a three-way repeated measures multiple analysis of variance, with post hoc analysis as was appropriate. Although no significant differences were detected among foot positions for the rectus femoris at 90 degrees, this knee angle produced significantly greater EMG activity for the neutral position compared with 150 degrees or 175 degrees. The 90 degrees angle was also superior to 175 degrees for the externally rotated position. The results for both the vastus medialis and vastus lateralis were similar, with the 90 degrees angle producing greater EMG activity than 175 degrees in the externally rotated position. In addition, the neutral position produced significantly more activity than the internally rotated position at 90 degrees. At 150 degrees, the neutral position was superior to the externally rotated position. Finally, at the 175 degrees knee angle, the highest level of EMG activity was with the foot internally rotated. Considering the combination of effects for EMG activity across all muscles tested, the 90 degrees knee angle with a neutral foot position may provide the most effective condition for rehabilitation of all muscles tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Fatigue-induced changes in myoelectric signal characteristics and perceived exertion.

Perceived exertion (RPE) has been used as a subjective indicator of exercise intensity for extremely light to supramaximal-level dynamic exercise. Little data exist on the relationship of RPE to physiological variables during sustained isometric exercise. Ten male subjects volunteered and participated in this investigation. Subjects were instructed to maintain a hand grip contraction of 50% of maximal effort until exhaustion. During this bout of exercise, electromyographic activity (EMG) and RPE values were recorded at 10 s intervals. The raw EMG signals were processed for frequency content (mean power frequency [MPF] and for signal amplitude (root mean squared [RMS]). RPE was recorded as a subjective value selected from a ten-point scale with ratio properties. Analysis of the data indicated that RPE was strongly correlated to both MPF: r2 = (-).922, and RMS: r2 = .729. These data imply that during sustained isometric exercise changes in perceived exertion are related closely to electromyographic activity of the contracting muscle.

The effects of active and passive recovery on short-term, high intensity power output.

The advantage of active over passive recovery from long and intermediate duration exercise is well documented. Success has been attributed to metabolite washout and/or lactate (La) utilization by the active musculature. This study was designed to determine whether active recovery was superior to passive rest during short duration, high intensity performance. On 4 separate days, six athletes performed a set of eight 6-s power tests separated by 30-s recovery intervals under two recovery conditions. Recovery conditions involved either sitting passively on the bike (P) or actively pedaling (A) at 60 rpm using 1 kg resistance. A MANOVA on peak power (PP), fatigue rate (F), and total work (TW) showed a significant difference due to recovery condition, F(3, 169); p < .0001. Separate ANOVAs revealed that PP (A = 1192.85 watts, P = 1134.57 watts; p < .0001) and TW (A = 6.59 kJ, P = 6.23 kJ; p < .0001) differed significantly between conditions. No difference was found for F (A = 80.12 watts.sec-1, P = 79.80 watts.sec-1). Results indicate that active recovery provides superior performance to passive rest in repeated short-term, high intensity power activities.

Caffeine, maximal power output and fatigue.

The purpose of this investigation was to determine the effects of caffeine ingestion on maximal power output and fatigue during short term, high intensity exercise. Nine adult males performed 15 s maximal exercise bouts 60 min after ingestion of caffeine (7 mg.kg-1) or placebo. Exercise bouts were carried out on a modified cycle ergometer which allowed power output to be computed for each one-half pedal stroke via microcomputer. Peak power output under caffeine conditions was not significantly different from that obtained following placebo ingestion. Similarly, time to peak power, total work, power fatigue index and power fatigue rate did not differ significantly between caffeine and placebo conditions. These results suggest that caffeine ingestion does not increase one's maximal ability to generate power. Further, caffeine does not alter the rate or magnitude of fatigue during high intensity, dynamic exercise.

Increased muscle strength in paralyzed patients after spinal cord injury: effect of beta-2 adrenergic agonist.

The administration of beta-2 adrenergic agonists in experimental animals result in an increased strength of skeletal muscle. In this study, we evaluated whether a beta-2 adrenergic agonist, metaproterenol, had an effect on muscle size and strength in a group of patients with muscular atrophy following spinal cord injury. Ten male subjects were randomly divided into 2 groups and agreed to participate in a prospective, double-blind, placebo-controlled, and crossover study. Metaproterenol (80 mg/day), or placebo, was administered orally for a period of 4 weeks. Muscle strength was measured by a force transducer interfaced with a microcomputer. Muscle size was calculated and expressed as a cross-sectional area of upper arm and forearm using a formula. Metaproterenol induced a significant increase of muscle strength in both groups of subjects, compared with placebo (p < .001). Similarly, there was an increase in a muscle size in the forearm following the administration of metaproterenol. Our data indicate that beta-2 adrenergic agonists may improve both muscle strength and size in patients with muscular atrophy following spinal cord paralysis.

Plasma lipid levels in active and sedentary premenopausal females.

Cross-sectional data on 19 long-distance runners (LD), 17 aerobic dancers (AD), 19 recreational joggers (RJ), and 15 inactive controls (IC) were examined for cardiovascular endurance and determination of plasma lipoproteins. Subjects included premenopausal eumenorrheic females who were non-smokers and presently not using oral contraceptives. Results indicated that all groups were similar in age, height and weight. Only the AD group had a significantly lower percent body fat (p less than .001) than the other groups. The LD, AD and RJ groups had a significantly higher VO2max than the IC group (p less than .05), and the LD and AD groups had a significantly higher VO2max than the RJ group (p less than .05). Analysis of a one-day food log indicated that the only difference in diet among the groups was a significantly lower intake of total and monounsaturated fat in the AD group (p less than .05) and a significantly lower intake of carbohydrates in the IC group than the AD group (p less than .05). Analysis of plasma lipids revealed no significant differences in any lipid variables among the groups. These findings indicate that healthy premenopausal eumenorrheic females with similar physical characteristics also have similar plasma lipid profiles regardless of their physical activity level.

Nutrient intake and psychological and physiological assessment in eumenorrheic and amenorrheic female athletes: a preliminary study.

The present study showed that amenorrheic athletes (AAs) scored higher on the Eating Attitudes Test (EAT) (p < .05) than eumenorrheic athletes (EAs), indicating more aberrant eating patterns in the first group. Scores on the EAT were inversely correlated with fat intake (p < .05), simple carbohydrate intake (p < .01), and percentage saturation of iron (p < .05) and were positively correlated with total iron binding capacity (p < .01) for the total sample. Physiological assessment of athletes revealed that there were no significant differences between groups in serum lipoproteins, with both EAs and AAs having serum lipid profiles indicative of low cardiovascular risk. Furthermore, low-density lipoprotein cholesterol was the only lipoprotein significantly and positively correlated with serum estradiol levels for the entire sample (p = .01). The present study was in agreement with previous work showing that scores of the EAT represent a primary difference between EAs and AAs; the present study was somewhat different than previous work in that serum lipoproteins were not significantly related to menstrual status.

Fitness, diet and coronary risk factors in a sample of southeastern U.S. children.

The purpose of this study was to evaluate the relationship between physical fitness variables and nutrient intake to coronary risk factors (CRF) in a sample of children living in the Southeastern U.S. A total of 22 sixth-grade children of whom 10 were boys (mean age = 11.83 +/- 0.3) and 12 were girls (mean age 11.7 +/- 0.3) volunteered for this study. Results indicated that boys in comparison to girls weighed more (54.0 +/- 10.8 kg versus 42.1 +/- 8.0 kg; p < 0.05), had a higher body mass index (BMI) (23.6 +/- 2.7 versus 20.2 +/- 3.3; p < 0.05), a higher lean body mass (37.8 +/- 6.0 kg versus 30.7 +/- 3.8 kg; p < 0.01), and a higher systolic blood pressure (115.7 +/- 11.1 versus 106.4 +/- 8.1; p < .0001). There were, however, no significant gender differences in serum lipoproteins or nutrient intake. Stepwise multiple regression analyses indicated that physical fitness variables which included VO2max, one-mile run for time, grip strength, and leg strength could significantly predict resting diastolic blood pressure (DBP) (F = 3.06; p < 0.05) and percent body fat (F = 4.98; p < 0.01) in children. Analysis of food intake revealed that total and saturated fat, and carbohydrate intake could predict serum triglycerides (TG) (F = 5.18; p = 0.01) while total kilocalorie, fat, and carbohydrate intake could significantly predict percent body fat (F = 3.42; p < 0.03). These findings may be clinically relevant since both serum triglyceride levels and percent body fat were well above the 50th percentile according to U.S. norms. In summary, the present study showed that measurements of muscular strength in addition to aerobic fitness are associated with DBP and percent body fat in children. Furthermore, it is recommended that nutrient intake be used when evaluating CRF in children due to its ability to predict TG and percent body fat.

Fluid-electrolyte balance associated with tennis match play in a hot environment.

Twenty (12 male and 8 female) tennis players from two Division I university tennis teams performed three days of round-robin tournament play (i.e., two singles tennis matches followed by one doubles match per day) in a hot environment (32.2 +/- 1.5 degrees C and 53.9 +/- 2.4% rh at 1200 hr), so that fluid-electrolyte balance could be evaluated. During singles play, body weight percentage changes were minimal and were similar for males and females (males -1.3 +/- 0.8%, females -0.7 +/- 0.8%). Estimated daily losses (mmol.day-1) of sweat sodium (Na+) and potassium (K+) (males, Na+ 158.7, K+ 31.3; females, Na+ 86.5, K+ 18.9) were met by the players' daily dietary intakes (mmol.day-1) of these electrolytes (males, Na+ 279.1 +/- 109.4, K+ 173.5 +/- 57.7; females, Na+ 178.9 +/- 68.9, K+ 116.1 +/- 37.5). Daily plasma volume and electrolyte (Na+, K+) levels were generally conserved, although, plasma [Na+] was lower (p < .05) on the morning of Day 4. This study indicated that these athletes generally maintained overall fluid-electrolyte balance, in response to playing multiple tennis matches on 3 successive days in a hot environment, without the occurrence of heat illness.