Biomedical subjects

D L Costill

Publications and source records attributed to D L Costill.

At least 73 records · Page 4Linked to original sources

PubMed1992

Carbohydrate nutrition and fatigue.

Carbohydrates are important substrates for contracting muscle during prolonged, strenuous exercise, and fatigue is often associated with muscle glycogen depletion and/or hypoglycaemia. Thus, the goals of carbohydrate nutritional strategies before, during and after exercise are to optimise the availability of muscle and liver glycogen and blood glucose, with a view to maintaining carbohydrate availability and oxidation during exercise. During heavy training, the carbohydrate requirements of athletes may be as high as 8 to 10 g/kg bodyweight or 60 to 70% of total energy intake. Ingestion of a diet high in carbohydrate should be encouraged in order to maintain carbohydrate reserves and the ability to train intensely. Ingestion of a high carbohydrate meal 3 to 4 hours prior to exercise ensures adequate carbohydrate availability and enhances exercise performance. Although hyperinsulinaemia associated with carbohydrate ingestion in the hour prior to exercise may result in some metabolic alterations during exercise, it may not necessarily impair exercise performance and may, in some cases, enhance performance. Carbohydrate ingestion during prolonged, strenuous exercise, where performance is often limited by carbohydrate availability, delays fatigue. This is due to maintenance of blood glucose levels and a high rate of carbohydrate oxidation, rather than a slowing of muscle glycogen utilisation, although liver glycogen reserves may be spared. During recovery from exercise, muscle glycogen resynthesis is critically dependent upon the ingestion of carbohydrate. Factors influencing the rate of muscle glycogen resynthesis include the timing, amount and type of carbohydrate ingested and muscle damage. Adequate carbohydrate availability before, during and after exercise will maintain carbohydrate oxidation during exercise and is associated with enhanced exercise performance.

Blood Glucose↗

PubMed1991

The role of anaerobic ability in middle distance running performance.

The purpose of this study was to assess the relationship between anaerobic ability and middle distance running performance. Ten runners of similar performance capacities (5 km times: 16.72, SE 0.2 min) were examined during 4 weeks of controlled training. The runners performed a battery of tests each week [maximum oxygen consumption (VO2max), vertical jump, and Margaria power run] and raced 5 km three times (weeks 1, 2, 4) on an indoor 200-m track (all subjects competing). Regression analysis revealed that the combination of time to exhaustion (TTE) during the VO2max test (r2 = 0.63) and measures from the Margaria power test (W.kg-1, r2 = 0.18; W, r2 = 0.05) accounted for 86% of the total variance in race times (P less than 0.05). Regression analysis demonstrated that TTE was influenced by both anaerobic ability [vertical jump, power (W.kg-1) and aerobic capacity (VO2max, ml.kg-1.min-1)]. These results indicate that the anaerobic systems influence middle distance performance in runners of similar abilities.

Adult↗

PubMed1991

Test development for the study of physical performance in wrestlers following weight loss.

This study was conducted to develop a testing protocol which would determine the extent of upper-body power output decrements in subjects following weight loss. Five athletes who had trained via upper-body exercise performed a 6-minute variable intensity arm crank test on an isokinetic ergometer before and after a 3-day, 4.5% body weight loss. Blood samples were drawn from a forearm vein pre- and 1, 3, and 5 min post-arm cranking for assessment of lactate, pH, hemoglobin, and hematocrit. The work performed pre-weight loss was significantly (paired t-test, p less than 0.05) greater than that performed post-weight loss. Repeated measures ANOVA yielded no significant differences in blood variables; however, pre-weight loss lactate values were higher and hemoglobin, hematocrit, and pH values were lower than post-weight loss values. It was concluded that a 4.5% body weight reduction resulted in performance decrements during this arm crank test. Survey information obtained from collegiate wrestlers (n = 14) subsequently tested under this protocol indicates the physical demands of this test approximate the physical demands of actual wrestling competition. It would therefore be appropriate to use this protocol during future testing of wrestlers in weight loss studies.

Adult↗

PubMed1991

Response of vitamin B-6 content of muscle to changes in vitamin B-6 intake in men.

Previous reports indicated that in growing rats the vitamin B-6 pool in muscle was relatively stable during deficiency but increased in response to increased vitamin B-6 intake. To determine whether human muscle would show a similar response 10 college-aged males received a low vitamin B-6 diet (1.76 mumol/d) for 6 wk followed by 6 wk on a self-selected diet supplemented with 0.98 mmol pyridoxine HCl/d. During depletion, excretion of pyridoxic acid rapidly adjusted to approximate the intake. Plasma pyridoxal phosphate concentrations at the end of the baseline, depletion, and supplementation periods were 81 +/- 51, 9 +/- 3, and 455 +/- 129 nmol/L, respectively, whereas muscle concentrations were 21 +/- 9, 20 +/- 4, and 25 +/- 7 nmol/g, respectively and total vitamin B-6 in muscle was 28 +/- 10, 27 +/- 4, and 35 +/- 10 nmol/g, respectively. These data provide further confirmation that the vitamin B-6 pools in skeletal muscle are resistant to depletion. They also demonstrate that in humans with constant body weight, vitamin B-6 supplementation is not associated with marked increases in vitamin B-6 in muscle.

Adult↗

PubMed1991

Effects of drink carbonation on the gastric emptying characteristics of water and flavored water.

The intent of this study was to determine whether adding carbonation to either water or a low calorie sport drink would affect gastric emptying (GE). Fifteen subjects rode for 20 minutes on a cycle ergometer at 55% of max VO2. After 5 minutes of exercise, the subjects ingested 5.5 ml/kg body weight of a test solution: water (W), carbonated water (CW), and a low calorie sport drink in both a carbonated (C2C) and noncarbonated (2C) form. At the end of each ride, the stomach was emptied through gastric aspiration. The results indicate that carbonation has no effect on GE. However, the type of drink did have an effect on GE, as both 2C and C2C emptied from the stomach at a slower rate than either W or CW. Subjective ratings of gastrointestinal comfort were similar for both carbonated and noncarbonated forms, and at no time did the subjects report discomfort. The results were independent of the exercise challenge, as exercise intensity, heart rate, and ratings of perceived exertion did not differ between experimental trials. It is concluded that carbonation does not affect the GE characteristics of a drink taken during submaximal exercise, but the flavoring system of the low calorie beverage decreased the rate of GE by as much as 25% when compared to water.

Adult↗

PubMed1991

Muscle glycogenolysis during differing intensities of weight-resistance exercise.

Skeletal muscle glycogen metabolism was investigated in eight male subjects during and after six sets of 70% one repetition maximum (1 RM, I-70) and 35% 1 RM (I-35) intensity weight-resistance leg extension exercise. Total force application to the machine lever arm was determined via a strain gauge and computer interfaced system and was equated between trials. Compared with the I-70 trial, the I-35 trial was characterized by almost double the repetitions (13 +/- 1 vs. 6 +/- 0) and half the peak concentric torque for each repetition (12.4 +/- 0.5 vs. 24.2 +/- 1.0 Nm). After the sixth set, muscle glycogen degradation was similar between I-70 and I-35 trials (47.0 +/- 6.6 and 46.6 +/- 6.0 mmol/kg wet wt, respectively), as was muscle lactate accumulation (13.8 +/- 0.7 and 16.7 +/- 4.2 mmol/kg wet wt, respectively). After 2 h of passive recovery without caloric intake, muscle glycogen increased by 22.2 +/- 6.8 and 14.2 +/- 2.5 mmol/kg wet wt in the I-70 and I-35 trials, respectively. Optical absorbance measurement of periodic acid-Schiff-stained muscle sections after the 2 h of recovery revealed larger absorbance increases in fast-twitch than in slow-twitch fibers (0.119 +/- 0.024 and 0.055 +/- 0.024, P = 0.02). Data indicated that when external work was constant, the absolute amount of muscle glycogenolysis was the same regardless of the intensity of resistance exercise. Nevertheless the rate of glycogenolysis during the I-70 trial was approximately double that of the I-35 trial.

Adult↗

PubMed1991

Carbohydrate for athletic training and performance.

Although fats and protein contribute to energy demands of exercise, carbohydrate, principally glycogen, is the preferred fuel for muscular activity. Because of its limited storage, depletion of muscle glycogen has been shown to be one factor responsible for fatigue and exhaustion during prolonged exercise. Thus, dietary carbohydrate plays a key role in exercise performance and training. When the athlete's diet is low in carbohydrate, little glycogen is resynthesized between training sessions, leaving the individuals with low muscle glycogen and a state of chronic fatigue. The most sensitive period for glycogen resynthesis is within the first few hours after exercise. Optimal recovery from an exhaustive exercise bout depends on a reasonably rich carbohydrate diet soon after the exercise. Such feedings serve to replenish carbohydrate stores in both liver and muscles. Exertional hypoglycemia can occur when liver glucose output falls below the rate of muscle glucose uptake. Though this seldom occurs in well-fed and highly trained individuals, sugar feedings during long-term exercise has been shown to enhance performance. Thus, the important role of dietary carbohydrate before, during and after endurance activities is well established, whereas our understanding of the nutritional needs for protein and fat remain unclear.

Dietary Carbohydrates↗

PubMed1991

Effect of increased training volume on blood lipids and lipoproteins in male collegiate swimmers.

This study was conducted to assess whether a previously described dose-response relationship between the amount of exercise and the magnitude of change in blood lipid and lipoprotein levels is observed with large volumes of exercise in young, healthy individuals. Blood lipid and lipoprotein levels were monitored during a 25-wk season of training and competition in experienced male collegiate swimmers, who were divided into two groups matched for swimming skill. After an initial 4-wk conditioning period for both groups, one group (N = 11) underwent a 6-wk period during which their training volume was increased from 22,000 m.wk-1 to 44,000 m.wk-1. The other group (N = 13) maintained their swimming distance at 22,000 m.wk-1 during this period. During the remaining 15 wk of the season, both groups swam approximately 22,000 m.wk-1. Swimmers' body weights did not change over the season, but body fat decreased significantly (P less than 0.01). No changes in HDL cholesterol were observed during the season in either the increased training or the regular training groups. Total and LDL cholesterol levels were lower at 20 wk than at the start of the study, but final levels did not differ from initial levels. Thus, the volume of swimming exercise may not be related to the degree of change in blood lipid and lipoprotein levels in healthy subjects with high activity levels.

Adult↗

PubMed1991

Influence of muscle glycogen depletion on the rate of resynthesis.

In an effort to determine what effect the degree of muscle glycogen depletion has on the rate of resynthesis, six male cyclists completed an exercise protocol that involved both one- and two-legged cycling. One leg completed 30 min of single-leg cycling, ten one-min sprints, and 30 min cycling with both legs. This resulted in a large degree of depletion (LD). The contralateral leg completed only 30 min of double-leg cycling and experienced a small amount of depletion (SD). Following the exercise, the subjects rested quietly for 6 h and were fed a 24% carbohydrate (CHO) solution every 20 min in order to achieve a CHO intake of 0.7 g.kg-1.h-1. Biopsies taken from the vastus lateralis muscle immediately after exercise revealed that the glycogen content of the LD leg decreased 93.9 (+/- 11.6) mmol.kg-1 w.w., whereas the SD leg used 49.3 (+/- 5.7) mmol.kg-1 w.w. (P less than 0.01). Subsequent biopsies taken at 2 and 6 h of recovery demonstrated that the rate of muscle glycogen resynthesis was significantly greater in the LD leg, averaging 8.8 (+/- 2.4) mmol.kg-1.h1 w.w, while the SD leg restored glycogen at a rate of 3.0 (+/- 1.0) mmol.kg-1.h-1 w.w. (P less than 0.05). Glycogen synthase activity, expressed as its activity ratio (I/D), was also greater (P less than 0.01) in the LD leg both immediately after exercise (0.45 +/- 0.05 vs 0.24 +/- 0.04) and at 2 h of recovery (0.54 +/- 0.06 vs 0.27 +/- 0.06).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Fluid replacement during prolonged exercise: effects of water, saline, or no fluid.

This study assessed the need to replace sodium in endurance exercise less than or equal to 6 h in duration by comparing responses to fluid replacement with water, saline (25 mmol.l-1), or no fluid. Eight subjects (five male, three female) participated in three 6-h exercise trials on an electrically braked cycle ergometer at 55% VO2max, at 30 degrees C and 50% r.h. In the water (W) and saline (S) trials, sufficient fluid was ingested to balance sweat and urinary fluid losses, while in the third trial, no fluid (NF) was ingested. Plasma sodium less than or equal to 130 mmol.l-1 was a criterion for trial termination. In the NF trial, heart rate, rectal temperature, plasma sodium, plasma aldosterone, and rating of perceived exertion were all significantly higher (P less than 0.001) than during W and S, whereas plasma volume was lower (P less than 0.001). On average, subjects terminated this trial 1.5 h prior to its scheduled completion, having lost 6.4% body weight. In contrast, no significant differences between fluid replacement with W or S were detected, although the effect of time on all aforementioned variables was highly significant (P less than 0.001). Saline intake was not associated with significantly higher plasma sodium during exercise than was water intake: plasma sodium decreased significantly during both W (to 135.5 +/- 0.5 mmol.l-1) and S (to 137.3 +/- 0.7 mmol.l-1). No subject had to terminate a trial based on plasma sodium less than or equal to 130 mmol.l-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Effects of warm-up on muscle glycogenolysis during intense exercise.

This study investigated the effects of preliminary exercise (warm-up) on glycogen degradation and energy metabolism during intense cycle ergometer exercise. After determination of VO2max, six male subjects were randomly assigned to perform warm-up (WU) and no warm-up (NWU) trials incorporating a 2 min standardized sprint ride (SR) at 120% of the power output attained at VO2max (POmax). Muscle biopsies and temperature (Tm) recordings were obtained from the vastus lateralis muscle. Tm was elevated above the resting level prior to the SR during the WU trial (37.7 +/- 0.1 vs 35.4 +/- 0.4 degrees C; P less than 0.05) and remained higher than the NWU trial after the SR (38.6 +/- 0.2 vs 37.1 +/- 0.4 degrees C; P less than 0.05). Similar trends existed for rectal temperature (Tr). The increases in Tm and Tr during the SR were both greater in the NWU trial (P less than 0.05). Muscle glycogen degradation was similar for the WU and NWU trials (30.8 +/- 3.7 vs 25.6 +/- 3.7 mmol.kg-1, respectively). When blood and muscle lactate concentrations after the SR were expressed relative to values before the SR, the WU trial resulted in a lower accumulation of blood lactate (6.5 +/- 0.9 vs 10.7 +/- 0.8 mEq.l-1; P less than 0.01) and muscle lactate (20.1 +/- 0.1 vs 23.4 +/- 2.2 mEq.kg-1 wet wt.; P less than 0.05). Furthermore, oxygen consumption during the 1st min of the SR was higher in the WU trial (2.3 +/- 0.2 vs 1.9 +/- 0.2 l.min-1; P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Adaptations to swimming training: influence of training volume.

In an effort to assess the contributions of a period of increased training volume on swimming performance, two matched groups of collegiate male swimmers were studied before and during 25 wk of training. For the first 4 wk of this study, the two groups trained together in one session per day for approximately 1.5 h.d-1. During the following 6 wk (weeks 5-11), one group (LONG) trained two sessions per day, 1.5 h in the morning and 1.5 h in the afternoon. The other group (SHORT) continued to train once each day, in the afternoon with the LONG group. Over the final 14 wk of the study, both groups trained together in one session per day (1.5 h.d-1). Although the swimmers experienced significant improvements in swimming power, endurance, and performance throughout the 25 wk study, there were no differences between the groups. However, during the 6 wk period of increased training, the LONG group experienced a decline in sprinting velocity, whereas the SHORT group showed a significant increase in sprinting performance. The test results suggest that a 6 wk period of two 1.5 h training sessions per day does not enhance performance above that experienced with a single training session of 1.5 h each day. It was also noted that both groups showed little change in swimming endurance and power after the first 8 wk of training, though their performances improved significantly after each taper period.

Analysis of Variance↗

PubMed1990

Influence of carbohydrate ingestion on counterregulatory hormones during prolonged exercise.

This study was undertaken to determine the effects of ingesting 5.0 (CHO-5), 6.0 (CHO-6), and 7.5 g/100 ml (CHO-7.5) carbohydrate (CHO) solutions on blood glucose and counterregulatory hormonal responses during prolonged intermittent exercise. Eight well-trained cyclists performed four trials consisting of seven 12-min cycling bouts at 70% of VO2max with 3 min rest between each ride. A final 12 min ride was an all-out self-paced performance ride. During the rest interval the subjects ingested either a water placebo (WP) or one of the CHO solutions at a rate of 8.5 mg/kg/h (approx. 150 ml). Blood samples were taken at 0, 25, 55, 85, and 115 min of exercise and were assayed for glucose, glucagon (GG), cortisol (CT), insulin (IN), epinephrine (EP), and norepinephrine (NE). Blood glucose levels were significantly lower in the WP trial compared to the CHO trials at 25 (4.6 +/- 0.2 vs 5.7 +/- 0.5 mmol/l) and 55 min (4.4 +/- 0.3 vs 5.0 +/- 0.8 mmol/l). At 85 min blood glucose was significantly lower in the WP compared to the CHO-6 and CHO-7.5 trials. GG and IN levels were not significantly different between trials; however, the GG:IN molar ratio was significantly higher in the WP than in the CHO-7.5 trial. CT was significantly elevated in the WP trial compared to the CHO-7.5 trial. EP and NE levels were not affected by CHO ingestion. These data suggest that CHO feedings prevent the typical hormonal responses which are responsible for hepatic glucose release, thus eliciting a possible hepatic glycogen sparing.

Adult↗

PubMed1990

Testosterone, cortisol, and creatine kinase levels in male distance runners during reduced training.

The purpose of this study was to examine if reduced training would reestablish normal testosterone, cortisol, and creatine kinase (CK) levels in male distance runners. Ten male runners (mean +/- SE) age 32.0 +/- 2.6 yrs, body fat 9.6 +/- 1.0%, VO2max 61.8 +/- 1.1 ml/kg/min) were monitored during 4 weeks of normal training (baseline training, BT) and 3 weeks of reduced training (RT). During BT running distance averaged 81 +/- 5 km/week, 6 days/week. During RT the runners reduced weekly training volume by 70% of BT to 24 +/- 2 km/week and training frequency to 5 days/week. Weekly resting blood samples were obtained between 0600-0900 hrs after an overnight fast. During BT resting total testosterone levels averaged 5.10 +/- 0.21 ng/ml, which is within the low ranges previously reported in male distance runners. Testosterone levels were not affected by RT (avg of 5.38 +/- 0.31 ng/ml). Cortisol levels were in the high range of normal during BT (23.61 +/- 1.18 ug/dl) and were not altered with RT (avg of 23.14 +/- 1.56 ug/dl). Creatine kinase was elevated (168 +/- 15 U/L) during BT and was significantly reduced (P less than 0.001) at weeks 1-3 of RT (avg of 99 +/- 9 U/L). These results suggest that normally training male runners have low resting total testosterone levels and cortisol levels in the high-normal range. Resting testosterone and cortisol were not responsive to the training reduction. Creatine kinase appears to be sensitive to relative changes in training.

Adaptation, Physiological↗

PubMed1990

Reduced training maintains performance in distance runners.

This investigation examined endurance runners during a 3-week reduction in training volume and frequency. Ten well-conditioned runners were monitored for 4 weeks while training at their normal weekly training distance (mean +/- SE) (81 +/- 5 km/week, 6 days/week). This period was designated as baseline training (BT). Sixty km/week were run at approximately 75% VO2max, and the remainder (21 km/week) at approximately 95% VO2max in the form of intervals and races. The runners then reduced weekly training volume (RT) by 70% of BT to 24 +/- 2 km/week and frequency by 17% to 5 days/week for 3 weeks. During RT 17 km/week was performed at approximately 75% VO2max and the remainder (7 km/week) at approximately 95% VO2max (intervals and races). The runners were tested weekly and performed 5-km races on a 200-m indoor track during Bt and after 2 and 3 weeks of RT. Maximal heart rate (HR) increased (P less than 0.05) by approximately 4 beats/min at RT week 3, which may have been associated with a decrease in estimated plasma volume (P less than 0.01) of 5.62 +/- 0.43%. Time to exhaustion during the VO2max tests increased (P less than 0.05) by 9.5% at RT week 3. No significant (P greater than 0.05) changes occurred with RT in body weight, % body fat, overall 5 km race times, VO2max, muscular power (vertical leap and Margaria power test), and citrate synthase activity (at 2 weeks of RT). No alterations in venous lactate, energy expenditure, and HR were observed during submaximal running at two speeds (approximately 65% and 85% VO2max) with RT.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Effects of warm-up on blood gases, lactate and acid-base status during sprint swimming.

A standardized 200-m front crawl sprint swim (SpS) was used to evaluate the effects of warm-up on pH, blood gases, and the concentrations of lactate ([La-]) and bicarbonate ([HCO3-]) in arterialized and venous blood. Eight trained male swimmers performed two randomly assigned 200-m front crawl swims at previously determined intensities corresponding to 120% VO2max. One swim was preceded by a warm-up (WU trial) which consisted of a 400-m front crawl swim (82% VO2max), 400-m flutter kicking (45% VO2max), and 4 x 50-m front crawl sprints (111% VO2max). The second was performed without warm-up (NWU trial). Blood was sampled from a hyperemized earlobe and an antecubital vein before the warm-up, 9 min after the warm-up (1 min before the swim), immediately following the SpS, and at 2, 5, 10, and 20 min after the SpS. The warm-up exercise resulted in a higher pre-SpS [La-] in arterialized blood (3.1 +/- 0.4 and 1.7 +/- 0.4 mmol x l-1, p less than 0.05), a higher hydrogen ion concentration ([H+]) in venous blood (45.9 +/- 0.9 and 42.2 +/- 0.8 nmol x l-1, p less than 0.001), and a lower arterialized blood [HCO3-] (25.1 +/- 0.9 and 22.2 +/- 0.8 mmol x l-1, p less than 0.05). The SpS was accompanied with higher heart rates during the WU trial (178 +/- 3 and 169 +/- 3 bpm; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Changes in selected blood measures during repeated days of intense training and carbohydrate control.

Ten runners were studied to determine whether selected blood measures were useful indices of the metabolic stress associated with intense training and dietary carbohydrate (CHO) deficiency. The runners performed two diet/training regimens, involving 5 repeated days of intense training approximately 80 min/d, approximately 80% VO2max) and dietary CHO control (8.0 g.kg-1.d-1, EQ-CHO; 3.9 g.kg-1.d-1, LO-CHO). Resting blood samples were obtained after a 3-day control period, after 3 and 5 days of intense training, and after 3 days of rest. Resting uric acid levels were significantly higher (P less than 0.05) after 3 and 5 days of training during the LO-CHO vs EQ-CHO regimen (353 +/- 21 vs 309 +/- 24, and 345 +/- 26 vs 302 +/- 26 mol.l-1, respectively). Resting thyroxine (T4) levels were higher (P less than 0.05) after 5 days of training during the LO-CHO vs EQ-CHO regimen (102.2 +/- 6.2 vs 83.7 +/- 4.5 nmol.l-1, respectively). While creatine kinase levels were elevated after both regimens (P less than 0.05), there was no difference between regimens. Serum cortisol (C) levels were reduced by 10% for both regimens (P less than 0.05), possibly due to an expansion in plasma volume (7.6 and 7.3% for the LO-CHO and EQ-CHO regimens, respectively). Resting FFA levels were increased (P less than 0.05) during both regimens, but there was no difference between the regimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1990

Fat storage in athletes: metabolic and hormonal responses to swimming and running.

Despite similar rates of energy expenditure during training, it has been suggested that swimmers store greater amounts of body fat than runners. To investigate these discrepancies, eight male swimmers (S) and runners (R) were monitored during 45 min of swimming or running (75% VO2max), respectively, and six triathletes were monitored during swimming (ST) and running (RT). Each group was also monitored during two hours of recovery. Venous blood samples were obtained before exercise, immediately after exercise (0 min) and at 15, 30, 60 and 120 min of recovery. These samples were analyzed for glucose, lactate, glycerol, free fatty acids (FFA), insulin, glucagon, norepinephrine (NE) and epinephrine (E). Expired gases and heart rates (HR) were obtained during exercise and also during recovery. The caloric cost of recovery was similar, but the RER results suggested increased fat oxidation during recovery for the S and the ST. Serum glucose was greater (P less than 0.05) immediately after exercise for R (6.71 +/- 0.29 mmol/l) and RT (6.40 +/- 0.26) compared to the S (4.97 +/- 0.19) and ST (4.87 +/- 0.18), and was significantly elevated for the initial 30 min of recovery. FFA were similar throughout the recovery period; however, blood glycerol was greater immediately after exercise (0 min) for R compared to S (NS) and was significantly elevated after exercise (0 min) for RT compared to ST. Differences in blood glucose or fat release were not explained by differences in NE or E; however, the glucacon-to-insulin ratio was significantly greater after exercise in the S and ST compared to the R and RT.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗