Effect of local cold application on glycogen recovery.

The purpose of this study was to investigate the effect of local cold application on muscle glycogen re-synthesis after exercise. Recreationally active male subjects (n=11) completed a 90-minute glycogen depleting ride, followed by 4 h of recovery. During recovery, ice was applied intermittently to one leg (IL) while the subjects other leg (CL) acted as a control. Intramuscular and rectal temperature was recorded continuously. A carbohydrate (1.8 g∙kg-1 bodyweight) beverage was supplied at 0 and 2 h post exercise. Muscle biopsies were taken immediately after exercise from the vastus lateralis and at 4 h post exercise for the analysis of muscle glycogen and muscle lactate. Leg circumference was measured 30, 60, 120, 180, and 240 minutes into recovery. The IL was colder than the CL from 15 minutes after initial ice application until the end recovery (P<0.05). Immediate post-exercise glycogen was similar between legs (55.3±7.4 vs. 56.1±7 mmol∙kg-1 wet weight for the iced vs. control, respectively). However, muscle glycogen was lower in the IL compared to the CL at 4 h post exercise (72±8.4 vs. 95±8.4 mmol∙kg-1 wet weight, respectively; P<0.05). Muscle lactate was lower in the IL after 4 h of recovery compared to the CL (1.6±.2 vs. 2.6±.2 mmol∙L-1, respectively; P<0.05). There was no difference in circumference between IL and CL. These data demonstrate a reduction in muscle glycogen re-synthesis with local cold application.

Refractive states of eyes and associations between ametropia and age, breed, and axial globe length in domestic cats.

OBJECTIVE: To determine the refractive states of eyes in domestic cats and to evaluate correlations between refractive error and age, breed, and axial globe measurements. ANIMALS: 98 healthy ophthalmologically normal domestic cats. PROCEDURES: The refractive state of 196 eyes (2 eyes/cat) was determined by use of streak retinoscopy. Cats were considered ametropic when the mean refractive state was ≥ ± 0.5 diopter (D). Amplitude-mode ultrasonography was used to determine axial globe length, anterior chamber length, and vitreous chamber depth. RESULTS: Mean ± SD refractive state of all eyes was -0.78 ± 1.37 D. Mean refractive error of cats changed significantly as a function of age. Mean refractive state of kittens (≤ 4 months old) was -2.45 ± 1.57 D, and mean refractive state of adult cats (> 1 year old) was -0.39 ± 0.85 D. Mean axial globe length, anterior chamber length, and vitreous chamber depth were 19.75 ± 1.59 mm, 4.66 ± 0.86 mm, and 7.92 ± 0.86 mm, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Correlations were detected between age and breed and between age and refractive states of feline eyes. Mean refractive error changed significantly as a function of age, and kittens had greater negative refractive error than did adult cats. Domestic shorthair cats were significantly more likely to be myopic than were domestic mediumhair or domestic longhair cats. Domestic cats should be included in the animals in which myopia can be detected at a young age, with a likelihood of progression to emmetropia as cats mature.

Human mRNA response to exercise and temperature.

The purpose of this research was to determine the mRNA response to exercise in different environmental temperatures. 9 recreationally active males (27±1 years, 77.4±2.7 kg, 13.5±1.5% fat, 4.49±0.15 L · min (-1) VO2 max) completed 3 trials consisting of 1 h cycling exercise at 60% Wmax followed by a 3 h recovery in the cold (7°C), room temperature (20°C), and hot (33°C) environments. Muscle biopsies were obtained pre, post, and 3 h post exercise for the analysis of glycogen and mRNA. Expired gases were collected to calculate substrate use. PGC-1α increased to a greater degree in the cold trial than in the room temperature trial (p=0.036) and the hot trial (p=0.006). PGC1-α mRNA was also higher after the room temperature trial than the hot trial (p=0.050). UCP3 and MFN2 mRNA increased with exercise (p<0.05), but were unaffected by temperature. COX was unaffected by exercise or temperature. Muscle glycogen decreased with exercise (p<0.05), but was no different among trials. Whole body VO2 was lower during exercise in the cold than exercise in the heat. However, VO2 was higher during recovery in the cold trial than in the room temperature and hot trials (p<0.05). This study presents evidence of PGC-1α temperature sensitivity in human skeletal muscle.

Environmental temperature and glycogen resynthesis.

This study investigated the effects of hot (H) and room temperature (RT) recovery environments on glycogen resynthesis. Nine male participants completed two trials, cycling for 1 h in a temperature-controlled chamber (32.6 degrees C), followed by 4 h of recovery at 32.6 degrees C (H) or 22.2 degrees C (RT). Rectal temperature was continuously recorded. A carbohydrate beverage (1.8 g/kg bodyweight) was supplied at 0 and 2 h post-exercise. Muscle biopsies were taken immediately, 2 h, and 4 h post-exercise for glycogen analysis. Blood samples were taken at 30, 60, 120, 150, 180, and 240 min into recovery for glucose and insulin analysis. Expired gas was collected at 105 min and 225 min into recovery to calculate whole body carbohydrate oxidation. Average core temperature, whole body carbohydrate oxidation, and serum glucose at 120, 150, 180 and 240 min was higher in H compared to RT (p<0.05). Muscle glycogen was higher in RT vs. H at 4 h (105+/-28 vs. 88+/-24 mmolxkg (-1) wet weight, respectively; p<0.05), but no different at 0 and 2 h. There was no difference in serum insulin. These data indicate the importance of minimizing the exposure to heat after exercise to improve recovery, specifically to improve glycogen resynthesis.

Glycogen synthesis after road cycling in the fed state.

The purpose of this study was to determine the effects of a recovery beverage immediately after exercise on rates of muscle glycogen resynthesis in response to road cycling when nutritional supplementation was supplied during exercise and a solid meal was served two hours after exercise. Eight trained male cyclists, (25+/-4 years, 69.3+/-5.2 kg, VO2 peak=4.5+/-0.4 L.min(-1)) performed two 62 km outdoor training rides in a double-blind, randomized cross-over experiment. Subjects received a food bar and a commercial sport drink during each ride. A recovery beverage (40 g CHO+20 g PRO) or a placebo (PL) was administered 30 min post-exercise. At 2 h post-exercise, a solid meal was provided for both trials. There was no difference between trials at any time point for glycogen (140+/-9, 56+/-8, and 70+/-8 mmol.kg(-1)wet wt.(-1).hr.(-1) for pre, post, and 4 h post, respectively). The addition of a supplemental recovery beverage ingested soon after exercise did not significantly increase the rate of muscle glycogen resynthesis after 4 h of recovery when nutritional supplementation is provided during exercise and a meal is consumed 2 h after exercise.

Glycogen resynthesis and exercise performance with the addition of fenugreek extract (4-hydroxyisoleucine) to post-exercise carbohydrate feeding.

The purpose of this study was to determine the effect of adding fenugreek extract (FG) to post-exercise carbohydrate feeding on glycogen resynthesis and subsequent exercise performance in normoglycemic male endurance athletes. A muscle biopsy sample was obtained from the vastus lateralis from subjects prior to exercise for 5 h at 50% of peak cycling power (52.1 +/- 3.3% of VO(2) peak). A second muscle biopsy sample was obtained immediately after exercise. Immediately after and 2 h after the second biopsy subjects ingested either an oral dose of dextrose (GLU) (1.8 g x kg BW(-1)) or GLU with FG containing 1.99 +/- 0.20 mg x kg(-1) 4-hydroxyisoleucine (GLU + FG) in a randomized, cross-over, double blind design. At 4 h post-exercise a third biopsy was taken and subjects received a standardised meal along with FG or a placebo capsule. At 15 h post-exercise subjects underwent their final muscle biopsy before completing a simulated 40 km cycling time trial. There was no difference in muscle glycogen at any time between GLU and GLU + FG. Additionally, 40 km time trial performance was similar for average power output (221 +/- 28 vs. 213 +/- 16 watts) and for time to completion (69.7 +/- 3.7 vs. 70.5 +/- 2.2 min) for the GLU and GLU + FG, respectively. Despite earlier data to the contrary, the present results do not support an effect of fenugreek supplementation on glycogen resynthesis, even though this may have been the result of differences in experimental protocol.

No gender-specific differences in mechanical efficiency during arm or leg exercise relative to ventilatory threshold.

The purpose of this study was to determine economy and mechanical efficiency in men and women during both arm cranking (AC) and leg cycling (LC) at 70%, 85%, 100%, and 115% of mode-specific ventilatory threshold (T(vent)). Recreationally active men (n=9) and women (n=9) with similar values for %VO2peak at T(vent) served as subjects. All subjects performed 5 min of exercise at each intensity of 70%, 85%, 100%, and 115% of T(vent) for both AC and LC. Economy was expressed as W/L/min. Gross efficiency (GE) was determined as the ratio of work accomplished to total energy expended (%). Delta efficiency (DE) was determined as the ratio of delta work accomplished to delta energy expended (%). Economy and efficiency during LC were greater than during AC in men and women. During AC or LC exercise, no sex differences were found in either economy (P=0.93 for AC, 0.98 for LC), GE (P=0.88 for AC, 0.75 for LC), or DE (P=0.57 for AC, 0.51 for LC). These findings indicate that men and women show similar economy and efficiency during both AC and LC exercise when subjects have similar %VO2peak at Tvent.

The addition of fenugreek extract (Trigonella foenum-graecum) to glucose feeding increases muscle glycogen resynthesis after exercise.

The purpose of this study was to determine the effects of ingesting an oral supplement containing 4-Hydroxyisoleucine (4-OH-Ile, isolated from fenugreek seeds [Trigonella foenum-graecum]) with a glucose beverage on rates of post-exercise muscle glycogen resynthesis in trained male cyclists. Following an overnight fast (12 hr), subjects completed a 90-minute glycogen depletion ride after which a muscle biopsy was obtained from the vastus lateralis. Immediately and 2 hours after the muscle biopsy, subjects ingested either an oral dose of dextrose (Glu) (1.8 g.kg BW(-1)) or 4-OH-Ile supplement (Glu+4-OH-Ile, including 2.0 mg.kg(-1) 4-OH-Ile with the same oral dose of dextrose) with a second muscle biopsy 4 hours after exercise. Post exercise muscle glycogen concentration was similar for both trials. Overall, there was a significant increase in glucose and insulin concentrations from time 0 throughout the majority of the 4-hour recovery period, with no significant differences between the two trials at any time point. Although muscle glycogen concentration significantly increased from immediately post exercise to 4 hr of recovery for both trials, the net rate of muscle glycogen resynthesis was 63% greater during Glu+4-OH-Ile (10.6+/-3.3 vs. 6.5+/-2.6 g.kg wet wt.(-1).hr.(-1) for the Glu+4-OH-Ile and Glu trials, respectively). These data demonstrate that when the fenugreek extract supplement (4-OH-Ile) is added to a high oral dose of dextrose, rates of post-exercise glycogen resynthesis are enhanced above dextrose alone.

Substrate utilization during arm and leg exercise relative to the ventilatory threshold in men.

BACKGROUND: The purpose of this study was to determine variations in substrate utilization in men during arm and leg exercise at 70 and 90% of mode specific ventilatory threshold (Tvent). METHODS: Ten males served as subjects. Limb total and muscle volumes were estimated in the right arm and leg with anthropometry. Ventilatory equivalence, excess CO2, and modified V-slope methods were used to determine Tvent. Subjects performed 15 min of exercise at 70 and 90%Tvent arm cranking (AC) exercise, and 70 and 90%Tvent leg cycling (LC) exercise. RESULTS: VO2, VE, and HR were higher during LC exercise at both intensities. However, arm and leg RPE were not different at 70 and 90%Tvent. There were no significant differences between modes at 70%Tvent in relative carbohydrate use (54.5+/-9.5 and 57.8+/-8.2% for AC and LC, respectively) and relative fat oxidation (45.5+/-9.5 and 42.2+/-8.2% for AC and LC, respectively). However, at 90%Tvent, relative carbohydrate oxidation was significantly higher during AC versus LC exercise (75.4+/-10.6 versus 68.6+/-9.0%, p<0.05). Energy expenditure (total kJ x min(-1) was significantly lower during AC exercise (14.5+/-2.9 and 18.4+/-3.4 for the 70 and 90%Tvent, respectively) versus LC exercise (27.1+/-3.3 and 34.8+/-4.1 for the 70 and 90%Tvent, respectively; p<0.05). CONCLUSIONS: These results indicate that substrate use during AC exercise is similar to LC exercise at 70%Tvent. However, as the exercise intensity increases, the smaller arm musculature becomes more dependent on carbohydrate utilization compared to the legs.

Sex differences in carbohydrate metabolism.

During submaximal endurance exercise, women oxidize more lipid and less carbohydrate as metabolic substrates than men. This is reflected in a lower glycogen utilization in skeletal muscle and lower hepatic glucose production for women compared with men. These latter observations may explain the lower leucine oxidation observed during endurance exercise in women. Animal and preliminary human study evidence suggests that 17-beta-estradiol may be a major determinant of the sex dimorphic response in carbohydrate metabolism during exercise. From a practical standpoint, it appears necessary for women to increase their dietary energy intake (and percentage derived from carbohydrates) for four days before a sporting event in order to supercompensate muscle glycogen concentrations. Sex differences in carbohydrate metabolism may have future implications for the care of patients with diabetes and inborn errors of lipid metabolism.

Validity and reliability of combining three methods to determine ventilatory threshold.

PURPOSE: This research was undertaken to validate a combination of methodologies to determine ventilatory threshold (VT). METHODS: Three methods were used individually and then combined to determine VT as follows: 1) ventilatory equivalencies, 2) excess CO2 production, and 3) a modified V-slope method. Three groups of participants-endurance athletes (N = 132), healthy, aerobically active adults (N = 31), and healthy, sedentary/low-active adults (N = 22)-were independently evaluated for VT and compared with the criterion standard lactate threshold (LT) defined as the first rise in blood lactate with increasing intensity of exercise. RESULTS: VT and LT were significantly correlated using the combined VT method within each study group (r = 0.98, 0.97, and 0.95, respectively; P < 0.001). Mean VO2 values at VT and LT were not significantly different between the three groups (P > 0.20). The combined method improved the determination rate of VT and reduced the standard deviation of the LT - VT difference by 80-170% over the individual methods. During test-retest procedures VO2lt and VO2vt determined by the combined method met criteria demonstrating further reliability. CONCLUSION: The combined method to determine VT is valid and reliable across a wide fitness range in healthy individuals and improves the determination rate and accuracy of VT determination over the use of single methods.

Glucose kinetics and substrate oxidation during exercise in the follicular and luteal phases.

The purpose of this investigation was to determine whether plasma glucose kinetics and substrate oxidation during exercise are dependent on the phase of the menstrual cycle. Once during the follicular (F) and luteal (L) phases, moderately trained subjects [peak O(2) uptake (V(O(2))) = 48.2 +/- 1.1 ml. min(-1). kg(-1); n = 6] cycled for 25 min at approximately 70% of the V(O(2)) at their respective lactate threshold (70%LT), followed immediately by 25 min at 90%LT. Rates of plasma glucose appearance (R(a)) and disappearance (R(d)) were determined with a primed constant infusion of [6,6-(2)H]glucose, and total carbohydrate (CHO) and fat oxidation were determined with indirect calorimetry. At rest and during exercise at 70%LT, there were no differences in glucose R(a) or R(d) between phases. CHO and fat oxidation were not different between phases at 70%LT. At 90%LT, glucose R(a) (28.8 +/- 4.8 vs. 33.7 +/- 4.5 micromol. min(-1). kg(-1); P < 0.05) and R(d) (28.4 +/- 4.8 vs. 34.0 +/- 4.1 micromol. min(-1). kg(-1); P < 0.05) were lower during the L phase. In addition, at 90%LT, CHO oxidation was lower during the L compared with the F phase (82.0 +/- 12.3 vs. 93.8 +/- 9.7 micromol. min(-1) .kg(-1); P < 0.05). Conversely, total fat oxidation was greater during the L phase at 90%LT (7.46 +/- 1.01 vs. 6.05 +/- 0.89 micromol. min(-1). kg(-1); P < 0.05). Plasma lactate concentration was also lower during the L phase at 90%LT concentrations (2.48 +/- 0.41 vs. 3.08 +/- 0.39 mmol/l; P < 0.05). The lower CHO utilization during the L phase was associated with an elevated resting estradiol (P < 0.05). These results indicate that plasma glucose kinetics and CHO oxidation during moderate-intensity exercise are lower during the L compared with the F phase in women. These differences may have been due to differences in circulating estradiol.

Blood glucose and glucoregulatory hormone responses to solid and liquid carbohydrate ingestion during exercise.

This study was conducted to compare blood glucose and glucoregulatory hormone responses to the ingestion of solid and liquid carbohydrate (CHO) during prolonged cycling, followed by 30 min of isokinetic cycling. Eight male cyclists randomly completed three cycling trials (LC = liquid CHO, SCE = solid CHO with water equal to LC, SCA = solid CHO + ad libitum water). Each subject cycled for 120 min at 65% of VO2max with CHO ingestion (0.6 g CHO/ kg/hr) at 0, 30, 60, 90, and 120 min. Subjects then completed a 30-min maximal isokinetic ride at 90 rpm. There was no significant (p < .05) difference between the trials for plasma glucose, insulin, glucagon, glycerol, lactate, RER, HR, VO2, RPE, and total work performed during the isokinetic ride. However, serum glucose was significantly lower in the SCE and SCA trials compared to LC at 80 min. The ingestion of a solid food containing CHO, protein, and fat with added water produced similar blood glucose, metabolic, glucoregulatory hormone, and exercise performance responses to those seen with the ingestion of liquid CHO.

Effects of estradiol on substrate turnover during exercise in amenorrheic females.

The purpose of this investigation was to determine the effects of transdermal estradiol (E2) replacement on substrate utilization during exercise. Amenorrheic females (N = 6) performed three exercise trials following 72 h of placebo (C 72) and 72 and 144 h of medicated transdermal estradiol (E2) treatment (E2 72 and E2 144). Exercise involved 90 min of treadmill running at 65% VO2max followed by timed exercise to exhaustion at 85% VO2max. Resting blood samples were obtained for glucose, insulin, free fatty acids (FFA), and E2. Exercise blood samples were obtained for E2, lactate, epinephrine, and norepinephrine. Rates of appearance and disposal were calculated for glucose and glycerol using a primed, continuous infusion of [6,6-2H] glucose and [2H5] glycerol. Medicated transdermal placement increased E2 significantly at rest, before exercise (35.03 +/- 12.3, 69.5 +/- 20.1, and 73.1 +/- 31.6 pg.mL-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). Resting FFA increased significantly following E2 treatment (0.28 +/- 0.16, 0.41 +/- 0.27, and 0.40 +/- 0.21 mmol.L-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). Glucose Ra was significantly decreased during exercise as a result of E2 replacement (21.9 +/- 7.7, 18.9 +/- 6.2, and 18.9 +/- 5.6 mumol.kg-1.min-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). Average glucose Rd also decreased during exercise as a result of E2 replacement (21.3 +/- 7.8, 18.5 +/- 6.4, and 18.6 +/- 5.8 mumol.kg-1.min-1 for the C 72, E2 72, and E2 144 trials, respectively, P < 0.05). However, the estimated relative contribution of plasma glucose and muscle glycogen to total carbohydrate oxidation was similar among the trials. Epinephrine values were significantly lower late in exercise during the E2 72 and E2 144 trials, compared with the C 72 trial (P < 0.05). These results indicate that elevated E2 levels can alter glucose metabolism at rest and during moderate intensity exercise as a result of decreased gluconeogenesis, epinephrine secretion, and/or glucose transport.

Effects of deep water and treadmill running on oxygen uptake and energy expenditure in seasonally trained cross country runners.

OBJECTIVE: The purpose of this study was to physiologically compare submaximal intensity deep water running (DWR) and treadmill running (TMR) exercise in trained athletes. EXPERIMENTAL DESIGN: Pre-test, post-test, 2 x 2 factoral design. SETTING: Treadmill exercise tests occurred in the Human Performance Laboratory. DWR trials took place in the deep end of the University pool. PARTICIPANTS: Seasonally trained college-aged male cross country runners (N = 8). Subjects completed a treadmill maximal oxygen consumption (VO2max) test, followed by a submaximal treadmill and deep water run at heart rates equivalent to 60% and 80% treadmill VO2max. MEASURES: Oxygen consumption (VO2), ventilation (VEstpd), rates of perceived exertion (RPE), energy expenditure (kcal.min-1), respiratory exchange ratio (RER), fat and carbohydrate oxidation (g.min-1) were measured during two 5 minute steady state stages for both trials. RESULTS: The trial by intensity interaction for VEstpd was significant, demonstrating greater ventilation during DWR as compared to TMR at 80% VO2max. The main effect of trial demonstrated that significantly higher RER and carbohydrate oxidation, and lower fat oxidation occurred during DWR as compared to TMR. VO2, RPE, and energy expenditure did not differ significantly between trials. CONCLUSIONS: DWR is a comparable form of submaximal intensity exercise as TMR in well-trained athletes. DWR does, however, maintain unique properties that differs it from TMR. Therefore, the concept of training specificity should be further considered when prescribing DWR and using it as an enhancement tool or substitute for dry land running.

Role of hope in academic and sport achievement.

Hope is the sum of goal thoughts as tapped by pathways and agency. Pathways reflect the perceived capability to produce goal routes; agency reflects the perception that one can initiate action along these pathways. Using trait and state hope scales, studies explored hope in college student athletes. In Study 1, male and female athletes were higher in trait hope than nonathletes; moreover, hope significantly predicted semester grade averages beyond cumulative grade point average and overall self-worth. In Study 2, with female cross-country athletes, trait hope predicted athletic outcomes; further, weekly state hope tended to predict athletic outcomes beyond dispositional hope, training, and self-esteem, confidence, and mood. In Study 3, with female track athletes, dispositional hope significantly predicted athletic outcomes beyond variance related to athletic abilities and affectivity; moreover, athletes had higher hope than nonathletes.

Cross-training between cycling and running in untrained females.

OBJECTIVE: The purpose of the study was to evaluate the cross-training response between running and cycling in untrained females. EXPERIMENTAL DESIGN: The following study involved a pretest, post-test, 3 x 3 factorial design. SETTING: Training (4 days-week-1, 10 weeks, 70-80% heart rate reserve) occurred at the Center for Exercise and Applied Human Physiology. Exercise testing occurred at the Veterans Hospital, Exercise Laboratory. PATIENTS AND PARTICIPANTS: Subjects included healthy, untrained females aged 18-25 years, (N = 18). INTERVENTION: Subjects were assigned to one of three (n = 6) training groups (run = R, cycle = C, both run and cycle = RC) matched on pre-training CE VO2max results. MEASURES: Graded treadmill run (TR) and cycle ergometer (CE) tests were performed on each subject to determine a mode specific VO2max and the lactate threshold (LT). Graded arm ergometer (AE) was performed to determine VO2max and heart rate and blood lactate at 20 and 40 Watts (W). Testing occurred prior to (0T), after 5 (5T) and after 10 weeks of training (10T). Body fat testing (hydrodensitometry at residual lung volume) was performed at 0T and 10T. RESULTS: TR and CE VO2max as well as TR and CE VO2 at the LT improved throughout the 10 weeks, regardless of training group. Although there were no changes in VO2max or blood lactate levels during AE, submaximal heart rates were significantly reduced over the 10 weeks, regardless of training group. CONCLUSIONS: These results indicate that the aerobic benefits of either run, cycle or combined run and cycle training are similar in untrained females. The LT and AE heart rate data demonstrate that improvements in VOmax due to ten weeks of training are a result of pronounced peripheral and moderate central adaptations.

Gender differences in substrate utilisation during exercise.

The selection and utilisation of metabolic substrates during endurance exercise are regulated by a complex array of effectors. These factors include, but are not limited to, endurance training and cardiorespiratory fitness, exercise intensity and duration, muscle morphology and histology, hormonal factors and diet. Although the effects of these factors on substrate utilisation patterns are well understood, the variation in substrate utilisation during endurance exercise between males and females is not. Because of the extreme heterogeneity in exercise protocols and individuals studied, the differences in substrate utilisation between males and females remain somewhat inconclusive. Regardless of heterogeneity, if the results from studies are interpreted collectively, an apparent gender difference in the selection and metabolism of substrates can be seen in sedentary individuals. However, this difference between genders diminishes as the level of cardiorespiratory fitness is increased to that of highly trained individuals. During rest and lower intensity exercise, the preferential metabolism of lipid occurs with a concomitant sparing of muscle glycogen. However, as the intensity of exercise is increased, the relative contribution of carbohydrate also increases. The exercise intensity at which the shift from lipid to carbohydrate is determined and regulated by the previously mentioned factors. Because the intensity and duration of exercise play a predominant role, the variation in exercise protocols poses a methodological concern when interpreting previous research. When attempting to compare the metabolism of substrates during endurance exercise, appropriate selection and interpretation of measurement techniques are necessary. Measurement techniques include the nonprotein respiratory exchange ratio, muscle and fat biopsies and the measurement of various blood metabolites, such as free fatty acids and glycerol. Similarly, in vitro analysis of lipolytic activity has also been demonstrated in males and females in response to varying levels of female gonadotrophic hormones. When comparing the substrate utilisation patterns between males and females, the area of hormonal regulation has received less attention. Often the catecholamine response to endurance exercise is measured; however, the gonadotrophic hormones, particularly those of the female, have received less attention when comparing genders. Indeed, the regulatory nature of the female gonadotrophic hormones has been demonstrated. Collectively, the effects of elevated estrogen, as in the luteal phase of menstruation, appear to promote lipolytic activity. Estrogen-mediated lipolytic activation occurs by apparently altering the sensitivity to lipoprotein lipase and by increasing the levels of human growth hormone (somatotropin), an activator of lipolysis.(ABSTRACT TRUNCATED AT 400 WORDS)

Reliability of the Tillman-Olsen procedure for determination of spondee threshold using recorded and live voice presentations.

This study investigated the reliability of the Tillman-Olsen procedure for establishing the spondee threshold (ST). Monitored live voice (MLV) and the Auditec of St. Louis recordings of the Central Institute for the Deaf spondees were used as stimuli. Ninety-five percent of 96 normal hearing subjects had test-retest STs within 5 dB and no subject varied more than 8 dB. Although these results represent good short term reliability for the Tillman-Olsen procedure, repeatability is no better than that produced by other procedures. Thresholds obtained by MLV were as reliable as the recorded spondees. It was concluded that recorded spondees offer no advantages over MLV testing for the experienced clinician. The recorded presentation gave STs that are very close to the normative value for speech specified by ANSl-1969. Live voice testing showed STs 4.7 dB better than when the Auditec recordings were used.