0063 The intensity guidelines for prescribing aerobic exercise were recently revised by ACSM to use %VO2reserve (%VO2R) rather than %VO2max. PURPOSE: The current study investigated the relationship of %VO2max and %VO2R with %Heart Rate Reserve (%HRR) in 630 initially sedentary individuals (ages 17 to 65). METHODS: Each participant completed 2 graded cycle tests to exhaustion before and after 20 weeks of training. VO2 and HR data were collected at the end of each stage. Resting HR and estimated resting VO2 (3.5 ml•kg−1•min−1) were additionally used to determine linear regressions of %HRR vs. %VO2max and %HRR vs. %VO2R. Slope and intercept were determined pre- and post-training for the total cohort and for subjects grouped by gender, race, age and baseline fitness (VO2max). RESULTS: Overall, and in all sub-groups, both pre- and post-training, the slope and intercepts were significantly different from 1.0 and 0, respectively for both %HRR vs. %VO2max and %HRR vs. %VO2R. However, the slopes and intercepts for %HRR vs. %VO2max were closer to the line of unity than were the slopes and intercepts of %HRR vs. %VO2R (p< 0.01 to 0.0001). More importantly, the calculated HR values for %HRR vs. %VO2max were closer (p<0.001) at 50% (+0.4±2.2 bpm) and 85% (+3.8 ± 3.2) than the values for %HRR vs. % VO2R at 50% (+8.2 ± 2.6 bpm) and 85% (+6.6 ± 3.4 bpm). Posttraining data differences were similar, though of smaller magnitude, with HR values at 50 and 85% VO2max more similar (p<0.01) to %HRR than were %VO2R HR values to %HRR. CONCLUSION: These results differ from those of Swain et al. who studied young adults during treadmill (n = 50) and cycle (n = 57) testing. Since %VO2R is a more difficult calculation than %VO2max and is less understood and since the differences in HR values within the normal aerobic training range were significantly closer using %VO2max, %VO2max is the better measure for prescribing exercise intensity. Supported by multiple grants from NIH/NHLBI.

1497 Although carbohydrate (CHO) feedings are commonplace during extended endurance exercise, the beneficial effects of CHO during extended work operations has received less attention. Due to the arduous nature of the job, the elevated energy expenditure of the wildland firefighter (WLFF) may compromise energy, glycogen and water balance (MSSE 35(10): 1760–65, 2003). PURPOSE: To determine the effects of liquid and solid CHO (L+S CHO) feedings on self-selected work rates during a 12-hour workshift of wildfire suppression. METHODS: Subjects included wildland firefighters (N = 29 WLFF) at two wildfires in MT during the 2003 season. Subjects consumed CHO [(200 ml.hr−1 hr, 20% CHO (160 kcal.hr−1 hr) every even hour and a solid (25g CHO, 10g protein,2g fat, 160 kcal.hr−1 hr) every odd hour (L+S CHO)] or a similarly flavored placebo (PLA) drink in a counter-balanced crossover design and were allowed ad lib water intake. Blood samples were collected at two-hour intervals with automated glucometers on a subset of subjects (n = 15). Self-selected work rate was determined using ActiCal accelerometer (MiniMitter, Inc.) count data converted to hourly rates of energy expenditure (kcal.hr−1 hr). Data were analyzed using a two way ANOVA with repeated measures. RESULTS: Although the mean hourly work rate was similar between trials during the morning (6 hours), it was significantly higher post lunch during the second half of the day for the L+S CHO (241 ± 56 and 202 ± 47 kcal.hr−1 hr for the L+S CHO and PLA, respectively, p<0.01). During the L+S CHO workshift, blood glucose (mM) was significantly higher (p<0.01) immediately prior to lunch (CHO = 5.9 ± 1, PLA = 5.3 ± 1.0) and at four (CHO = 6.4 ± 1.0, PLA = 5.7 ± 0.6) and six hours (CHO = 6.2 ± 1.1, PLA = 5.1 ± 0.7) post lunch. CONCLUSIONS: Self-selected work rate is higher during the second half of wildfire suppression shifts when high CHO foods are delivered at a rate of 160 kcals.hr−1 hr. Supplemental foods should be evaluated to determine the effects on cognitive function, critical decision-making, and overall safety during extended operations. Supported by Missoula Technology and Development Center and Gatorade Science Institute

1743 Clarification of the effect of the menstrual phases on substrate use pattern to exercise remains to be elucidated with respect to exercise mode, intensity, and duration. PURPOSE: The purpose of this study was to determine the variations of substrate oxidation in the follicular (F) and luteal (L) phases for women during progressive arm and leg exercise at 70, 85, 100, and 115% of mode specific ventilatory threshold (Tvent). METHODS: Eumenorrheic recreationally active women (n = 10) served as subjects. Ventilatory equivalence, excess CO2, and modified V-slope methods were used to concurrently determine Tvent. All subjects performed 5 min exercise at each intensity of 70, 85, 100, and 115% of Tvent arm cranking (AC) and Tvent leg cycling (LC), once during the follicular phase (5–9 days after onset of menses) and once during the luteal phase (22–27 days after onset of menses). Total carbohydrate (CHO) and fat (FAT) oxidation were determined with indirect calorimetry. Significance was set at p<0.05. RESULTS: There were no significant differences between the two menstrual phases in relative contribution (%) of CHO during AC (70%Tvent: F = 52.1 ± 8.2, L = 50.7 ± 20.9; 85%Tvent: F = 60.0 ± 10.1, L = 59.0 ± 18.8; 100%Tvent: F = 66.3 ± 12.9, L = 64.0 ± 18.8; 115%Tvent: F = 71.2 ± 10.2, L = 69.1 ± 18.7) and during LC (70%Tvent: F = 51.6 ± 11.4, L = 53.5 ± 11.3; 85%Tvent: F = 58.0 ± 10.2, L = 60.9 ± 10.1; 100%Tvent: F = 64.0 ± 10.3, L = 63.1 ± 12.2; 115%Tvent: F = 68.9 ± 11.0, L = 68.5 ± 13.7). Similarly, there were no differences in %FAT contributions during AC or LC at any intensity across menstrual phases. It is noteworthy that as exercise intensity approached 100%Tvent, there was a tendency towards higher whole body CHO oxidation (expressed as g CHO•min−1, kJ CHO•kg−1•min−1, and μmol CHO•kg−1•min−1) in F vs. L during both AC and LC exercise. CONCLUSIONS: These findings indicate that whole body substrate utilization was similar during exercise in the follicular and luteal phases in recreationally active women. Whole body patterns of fuel utilization between the two phases may be more dependent on exercise mode, intensity and duration including individual variations in ovarian hormone concentrations.

2191 Prior short-term exercise studies have shown no effect of carbohydrate (CHO) supplementation on post-exercise suppression of salivary Immunoglobulin-A (sIgA). PURPOSE: This study evaluated the effects of CHO supplementation in wildland. re. ghters (WLFF) over an extended work shift on post-exercise and 12 hr recovery sIgA values. METHODS: Subjects were 29 WLFF evaluated during an extended shift of firefighting. In a single blind, random crossover design, WLFF on subsequent days received either a CHO [200ml/hr, 20% maltodextrin (160 kcal/hr)] or placebo (PLA) drink each hour. At the completion of the shift the CHO group received an additional bolus of 400 kcal CHO. Four minute forced salivary samples were collected pre- and post-shift and the morning after each treatment. Samples were analyzed using an Elisa assay. A two-way repeated measures ANOVA was used to evaluate the salivary data. RESULTS: Immediately post-shift both groups had a significant decrease in sIgA content over pre-shift values while the CHO group had significantly less sIgA suppression compared to the PLA group (pre-shift: CHO = 429 ± 139, PLA = 437 ± 159; post-shift: CHO = 290 ± 160, PLA = 230 ± 111, p<0.05). Following 12 hours of rest the CHO groups had returned to pre-shift values, while the PLA group remained significantly immune depressed (CHO = 442 ± 171, PLA = 337 ± 136, p<0.05). Additionally, during the final 6 hours of the CHO trial the subjects performed 23% more work (CHO = 486 ± 36, PLA = 395 ± 28 kcal/hr, p<0.01) and maintained higher blood glucose values compared to PLA, but there were no differences in RPE across trials. CONCLUSION: Exercise has been shown to cause a decrease in sIgA and is associated with increased incidence of upper respiratory tract infection. CHO supplementation during long shifts of arduous work in WLFF enhances maintenance of immune function and improved recovery after extended arduous work in spite of the greater self-selected work with CHO. The mechanism for the improved immune function is unknown but may be related to increased cortisol concentrations associated with longer duration exercise. Supported by the U.S. Forest Service, Missoula Technology Development Center.

0062 In 1998, the ACSM revised its guidelines for prescribing the intensity of aerobic exercise, adding that one could lower the intensity to 40% VO2 reserve (VO2R) for “quite Unfit” people. PURPOSE: To investigate the relationship between %VO2R and the ventilatory threshold (vt) in 442 initially sedentary individuals (ages 17 to 65). METHODS: Each participant completed 2 graded cycle tests to exhaustion before and after 20 weeks of training. VO2 and heart rate data were collected at the end of each stage. The absolute (ml•kg−1•min−1) and relative (%VO2R) values for VO2vt were determined for each subject. RESULTS: The average absolute values for VO2vt were about 10–14 ml•kg−1•min−1 for 183 subjects whose VO2 max was 15.4–29.9 ml•kg−1•min−1. This is similar to the value of 15 ml•kg−1•min−1 that Shephard states is associated with activities of daily living. The range of relative values for the VO2vt of these subjects was 42–83% VO2R, with most subjects between 50% and 70% VO2R. Intensities below VO2vt are generally aerobic in nature and can be done without much distress. It should be noted that these subjects began the training program by exercising for 30 minutes at the heart rate associated with 50% VO2 max and had few problems. CONCLUSION: Because “quite Unfit” sedentary subjects are already doing enough activity in their daily lives to maintain a VO2vt at levels that are generally greater than 50% VO2R, it is not necessary to reduce the prescribed intensity to 40% VO2R, as recommended by the ACSM. Supported by multiple grants from NIH-NHLBI.

1499 Purpose: This study was designed to validate algorithms for predicting energy expenditure (EE, kcals/kg/min) from two electronic activity monitors. An algorithm is defined as a series of analytical steps for processing the raw activity monitor data into units of EE. Methods: 8 men (Mean[SD]: 25.8[5.9] yrs, 176.2[9.6] cm body height, 80.3[23.3] kg body mass) and 5 women (24.4[6.2] yrs, 173.2[8.9] cm, 64.1[6.6] kg) volunteered to perform 7 outdoor activities common to wildland fire suppression work: Slow and fast self-paced hiking at level grade, 3 paces (slow, medium, fast) of line digging with a Pulaski tool, and self-paced uphill and downhill hiking. Each subject wore clothing (hiking boots, long pants, long sleeved shirt and under shirt, work gloves) and gear (15.68 kg waist pack, Pulaski tool) similar to that required by actual wildland firefighters. EE was determined from oxygen uptake and RER measures recorded using a portable metabolic system (VmaxST, SensorMedics) worn on the back during all activities. The Actical (AC; Mini Mitter Co, Inc.) and MTI (AM 7164–1.2; Manufacturing Technology, Inc.) activity monitors were mounted to a card and worn in the left chest pocket. Total mass carried by each subject during the test session approximated 21 kg. Standard regression analyses were used to derive EE prediction models from output for each activity monitor. 2-factor RM ANOVA was used to evaluate differences in prediction model output with actual EE. Results: Data for 2 subjects were incomplete due to lost MTI data, so analyses were completed using the 13 subjects with complete data. Composite models (using data for all 7 activities) for the MTI (EE = 0.08699+ 4.543E-6×MTI; P = 0.05) and Actical monitors (EE = 0.09452+ 4.169E-6×AC; P = 0.04) were developed. A 2-step Actical model was also used: EE = 0.08576+ 1.454E-5×AC (P = 0.05) when AC>600 and AC < 2350, and EE = 0.04973+ 1.138E-5×AC (P<0.001) when AC > 2350. Each model was then applied to the min-by-min activity data over the entire collection period and summarized as absolute EE (kcals) expended within light, moderate, and vigorous exercise intensities, as well as total EE for the measurement period. Predicted EE within each exercise intensity did not differ significantly between models nor with actual EE (P>0.10). However, none of the prediction models could accurately predict EE for uphill hiking. Conclusion: Each of the derived EE prediction models, for both the Actical and MTI monitors, appear to predict gross summary measures of EE accurately using a methodology (chest pocket location) specific to assessment in wildland firefighters. Supported by the U.S. Forest Service, Missoula Technology and Development Center.

0855 The resynthesis of muscle glycogen post exercise is critical to endurance performance during subsequent exercise bouts. Previous research generally supports the concept that supplemental protein and/or select amino acids may accelerate rates of glycogen resynthesis beyond carbohydrate alone. PURPOSE: The purpose of this study was to determine the effects of ingesting a commercial supplement containing 4-hydroxyisoleucine (4 OH-Ile), isolated from fenugreek seeds, with a glucose beverage (GLU+4 OH-Ile) on rates of post-exercise muscle glycogen resynthesis in trained male cyclists. METHODS: Following an overnight fast (12 hr), subjects completed a 90-minute glycogen depletion interval ride after which a muscle biopsy was obtained from the vastus lateralis (0hr). During one trial, subjects received a 1.8 g.kg BW−1 BW oral dose of dextrose (GLU) immediately post biopsy and again 2 hours later. During another trial, subjects received the same dose of dextrose with 2.0 mg.kg−1 4-OH-Ile (GLU+4 OH-Ile) at the same feeding schedule. A second muscle biopsy was obtained from the same leg 4 hours after the initial feeding (4hr). Blood samples for insulin and glucose were obtained throughout the recovery period. Trials were completed double blind in a randomized, counterbalanced order. Statistical significance was set at p<0.05. RESULTS: Post exercise (0hr) muscle glycogen concentration was similar for both trials. Overall, there was a significant increase in glucose and insulin concentrations from 0hr throughout the majority of the 4-hour recovery period. However, there were no significant differences in glucose or insulin concentration between the two trials at any time point. Although muscle glycogen concentration significantly increased from immediately post exercise (0hr) to 4hr of recovery for both trials, the average rate of muscle glycogen resynthesis was 63% greater during the GLU+4 OH-Ile trial (10.6 ± 3.3 vs. 6.5 ± 2.6 g.kg wet wt.−1.hr−1 hr. for the GLU+4 OH-Ile and GLU trials, respectively). CONCLUSION: These data demonstrate that ingestion of the commercial 4-hydroxyisoleucine supplement along with an oral dose of dextrose stimulates skeletal muscle glucose uptake and muscle glycogen resynthesis by way of an insulin-independent mechanism. Funded by Technical Sourcing International, Inc.

This study investigates whether there are major gene effects on oxygen uptake at the ventilatory threshold (VO(2VT)) and the VO(2VT) maximal oxygen uptake (VT%VO(2 max)), at baseline and in response to 20 wk of exercise training by using data on 336 whites and 160 blacks. Segregation analysis was performed on the residuals of VO(2VT) and VT%VO(2 max). In whites, there was strong evidence of a major gene, with 3 and 2% of the sample in the upper distribution, that accounted for 52 and 43% of the variance in baseline VO(2VT) and VT%VO(2 max), respectively. There were no genotype-specific covariate effects (sex, age, weight, fat mass, and fat-free mass). The segregation results were inconclusive for the training response in whites, and for the baseline and training response in blacks, probably due to insufficient power because of reduced sample sizes or smaller gene effect or both. The strength of the genetic evidence for VO(2VT) and VT%VO(2 max) suggests that these traits should be further investigated for potential relations with specific candidate genes, if they can be identified, and explored through a genome-wide scan.

In the HERITAGE Family Study, 675 sedentary, healthy, white and black men and women, aged 17 to 65 years, performed 20 weeks of supervised cycle ergometer exercise at the same relative intensity and weekly volume. As a group, subjects had normal mean baseline lipid levels for North Americans with the exception of below average high density lipoprotein cholesterol (HDL-C) levels. A significant mean increase in plasma HDL-C of 3.6 % was observed; however, there was marked variability in responsiveness to training, ranging from a mean 9.3 % decrease in Quartile 1 of HDL-C response to a mean 18 % increase in Quartile 4 (P < 0.0001 by ANOVA). Parallel changes in HDL(2)-C and HDL(3)-C, apolipoprotein A-I levels, and lipoprotein lipase activity were noted across quartiles. The change in HDL-C across quartiles was inversely related to baseline HDL-C (p < 0.0001) and to changes with training in plasma triglycerides (p = 0.0007). No significant differences in HDL-C response were observed across quartiles by sex, race, age, or increase in VO(2)max with training; however, weak positive associations were observed with age-adjusted education level and with reduction in abdominal fat and increase in VO(2)max at the ventilatory threshold following training. Multivariate regression analysis including baseline variables and training responses only accounted for 15.5 % of the variability in the HDL-C response to training. Thus, marked variability was found in the HDL-C response to the same endurance exercise training stimulus with only a modest amount of the response predictable by identified nongenetic factors.

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 (V)over dotO(2) 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 (V)over dotO(2)lt and (V)over dotO(2)vt 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.

UNLABELLED:The purpose of this study was to evaluate the effect of exercise training intensity relative to the ventilatory threshold (VT) on changes in work (watts) and VO2 at the ventilatory threshold and at maximal exercise in previously sedentary participants in the HERITAGE Family Study. We hypothesized that those who exercised below their VT would improve less in VO2 at the ventilatory threshold (VO2vt) and VO2max than those who trained at an intensity greater than their VT. Supervised cycle ergometer training was performed at the 4 participating clinical centers, 3 times a week for 20 weeks. Exercise training progressed from the HR corresponding to 55% VO2max for 30 minutes to the HR associated with 75% VO2max for 50 minutes for the final 6 weeks. VT was determined at baseline and after exercise training using standardized methods. 432 sedentary white and black men (n = 224) and women (n = 208), aged 17 to 65 years, were retrospectively divided into groups based on whether exercise training was initiated below, at, or above VT. RESULTS:1) Training intensity (relative to VT) accounting for about 26% of the improvement in VO2vt (R2 = 0.26, p < 0.0001). 2) The absolute intensity of training in watts (W) accounted for approximately 56% of the training effect at VT (R2 = 0.56, p < 0.0001) with post-training watts at VT (VT(watts)) being not significantly different than W during training (p > 0.70). 3) Training intensity (relative to VT) had no effect on DeltaVO2max. These data clearly show that as a result of aerobic training both the VO2 and W associated with VT respond and become similar to the absolute intensity of sustained (3 x /week for 50 min) aerobic exercise training. Higher intensities of exercise, relative to VT, result in larger gains in VO2vt but not in VO2max.

Purpose: This study investigates the familial resemblance of (V)over dotO(2) at the ventilatory threshold ((V)over dotO(2vt)) from 199 nuclear families (100 White and 99 Black) participating in the HERITAGE Family Study. Methods: (V)over dotO(2vt), (mL.min(-1)) was determined in the sedentary state and again after 20 wk of aerobic cycle ergometer exercise training in 339 individuals (131 parents and 228 of their offspring), aged between 17 and 65 yr. (V)over dotO(2vt) was adjusted for weight, age, fat mass, and fat-free mass by using regression methods. Results: There was evidence for significant familial resemblance in the sedentary state for (V)over dotO(2vt) (maximal heritability = 58% in White and 54% in Black families) and (V)over dotO(2vt)/(V)over dotO(2max) (maximal heritability = 38% in White and 39% in Black families), Spouse, sibling, and parent-offspring relationships for (V)over dotO(2vt) were significant at baseline, suggesting that both genetic and shared environmental factors may contribute to the familial resemblance in the sedentary state. There was a moderate familial component in the response of (V)over dotO(2vt) to aerobic exercise training in Whites (22%) and a larger component in Blacks (51%). In Blacks, the familial effect for (V)over dotO(2vt)/(V)over dotO(2max) appeared to be accounted for by fat and fat-free mass. Conclusion: These results show a strong familial contribution to (V)over dotO(2vt) in the sedentary state and to the response of (V)over dot(O2vt) to aerobic exercise training.

The purpose of this investigation was to determine the effects of load carriage on transit time during simulated escape route evacuation. Subjects (8 males, 5 females) completed two maximal field hikes in random order on two successive days (16 kg [35 lb] line gear pack trial and no pack trial). Subjects carried a fire shelter and a Pulaski (the most commonly used fireline construction tool in the United States, consisting of a hoe/ax combination with an 80 cm handle) during each trial. Trials were completed on a dirt trail 660.5 m in length with a vertical rise of 137 m (average grade = 20.75%). Expired air samples were analysed continuously during each trial (Cosmed K4 or Aerosport VO2000). Blood samples were collected before and 2 min after exercise for lactate analysis. Transit time was significantly faster during the No pack trial, representing a 21.5 and 26.3% faster transit time for males and females, respectively. For the males, mean VO2 was higher during the No pack trial. The difference in blood lactate (peak–rest) was significantly higher during the Pack trial for the male subjects. High correlations between peak VO2 (L min–1) and transit rates were noted (r = 0.82 for the Pack trial and 0.87 for the No pack trial), indicating the contribution of aerobic fitness to transit time. These data suggest that escape routes should include a physical strain index related to load carriage, distance and slope and that line gear weight standards should be further evaluated.

The purpose of this study was to evaluate relationships between upper body power (UBP) and cross-country ski skating race velocity (R) in a cross sectional representation of cross-country skiers. Additionally, cross-country skiers' UBP was compared to UBP of distance runners. Participants (n = 195) were tested on a Street Arm Ergometer for UBP using a ramped maximal UBP test simulating a double poling motion. A strong relationship (r = 0.89) between UBP and RV in skiers was determined. High school skiers were separated into slow and fast groups based on reported RV; significant differences (p < 0.05) in both UBP was found to be an effective partial predictor of RV, independent of gender. Mean UBP for the cross-country runners was 46% of mean UBP for the cross-country skiers. With UBP contributing so much to performance in cross-country ski racing, it is recommended that cross-country skiers focus a large portion of their training on the specific development of that fitness component.

PURPOSE:This study evaluated whether cross-country skiers who did not respond positively to a training program consisting of high volume and low intensity would improve if high-intensity training volume was doubled during a subsequent training year. METHODS:During the first year of the study, cross-country skiers (N = 14) were evaluated for VO2max, VO2threshold, lactate response, max arm power, and competitive results after a standard training program. During the second year, the athletes were divided into a control group (athletes who had responded well to the training) and a treatment group (athletes who had responded poorly to the training). The control group (N = 7) repeated the previous year's training program. The treatment group (N = 7) was given a modified training program which increased high-intensity training time as a percentage of total training from < 17% to > 35% and decreased low-intensity training volume 22%. RESULTS:The treatment group, using the high-intensity training program, demonstrated significantly improved VO2max, VO2threshold, max arm power, and competitive results (P < 0.05). CONCLUSIONS:Increased volume of high-intensity training may improve competitive results in cross-country skiers who fail to respond to increased volume of low-intensity training.