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Young athletes may be at risk for low energy availability (LEA) or dietary habits that are indicative of eating disorders. Thus, the purpose of the current study was to investigate the prevalence of LEA among high school athletes and examine those at risk for eating disorders. A secondary aim was to examine relationships between sport nutrition knowledge, body composition, and LEA. Methods: 94 male (n = 42) and female (n = 52) mean ± SD age: 18.09 ± 2.44 y; height: 172.6 ± 9.8 cm; body mass: 68.7 ± 14.5 kg; BMI: 22.91 ± 3.3 kg·m−2) athletes completed a body composition assessment and electronic versions of the abridged sports nutrition knowledge questionnaire (ASNK-Q), brief eating disorder in athletes questionnaire (BEDA-Q), and the low energy availability for females questionnaire (LEAF-Q; females only). Results: 52.1% of female athletes were classified as being at risk for LEA. Moderate inverse relationships existed for computed LEAF-Q scores and BMI (r = −0.394; p < 0.01). A total of 42.9% of males (n = 18) and 68.6% of females (n = 35) were at risk for eating disorders, with females being at greater risk (p < 0.01). Body fat percentage was a predictor (β = −0.095; p = −0.01) for eating disorder risk status. For every 1 unit increase in body fat percentage, athletes were 0.909 (95% CI: 0.845–0.977) times less likely to be classified as at risk for an eating disorder. Male (46.5 ± 13.9) and female (46.9 ± 11.4) athletes scored poorly on the ASNK-Q, with no differences between sex (p = 0.895). Conclusions: Female athletes were at a greater risk for eating disorders. No relationships existed between sport nutrition knowledge and %BF. Female athletes with a higher %BF had a lower risk for an eating disorder and risk for LEA.

The aerobic cost of running (CR), an important determinant of running performance, is usually measured during constant speed running. However, constant speed does not adequately reflect the nature of human locomotion, particularly competitive races, which include stochastic variations in pace. Studies in non-athletic individuals suggest that stochastic variations in running velocity produce little change in CR. This study was designed to evaluate whether variations in running speed influence CR in trained runners. Twenty competitive runners (12 m, VO2max=73 + 7 ml/kg, 8f, VO2max=57 + 6 ml/kg) ran four 6-minute bouts at an average speed calculated to require ~90% ventilatory threshold (VT) (measured using both v-slope and ventilatory equivalent). Each interval was run with minute-to-minute pace variation around average speed. CR was measured over the last 2 min. The coefficient of variation (CV) of running speed was calculated to quantify pace variations: + 0.0 m∙s-1 (CV = 0%), + 0.04 m∙s-1 (CV = 1.4%), + 0.13 m∙s-1(CV = 4.2%), and + 0.22 m∙s-1(CV = 7%). No differences in CR, HR, or blood lactate (BLa) were found amongst the variations in running pace. Rating of perceived exertion (RPE) was significantly higher only in the 7% CV condition. The results support earlier studies with short term (3s) pace variations, that pace variation within the limits often seen in competitive races did not affect CR when measured at running speeds below VT.

During competitive events, the pacing strategy depends upon how an athlete feels at a specific moment and the distance remaining. It may be expressed as the Hazard Score (HS) with momentary HS being shown to provide a measure of the likelihood of changing power output (PO) within an event and summated HS as a marker of how difficult an event is likely to be perceived to be. This study aimed to manipulate time trial (TT) starting strategies to establish whether the summated HS, as opposed to momentary HS, will improve understanding of performance during a simulated cycling competition. Seven subjects (peak PO: 286 ± 49.7 W) performed two practice 10-km cycling TTs followed by three 10-km TTs with imposed PO (±5% of mean PO achieved during second practice TT and a self-paced TT). PO, rating of perceived exertion (RPE), lactate, heart rate (HR), HS, summated HS, session RPE (sRPE) were collected. Finishing time and mean PO for self-paced (time: 17.51 ± 1.41 min, PO: 234 ± 62.6 W), fast-start (time: 17.72 ± 1.87 min, PO: 230 ± 62.0 W), and slow-start (time: 17.77 ± 1.74 min, PO: 230 ± 62.7) TT were not different. There was a significant interaction between each secondary outcome variable (PO, RPE, lactate, HR, HS, and summated HS) for starting strategy and distance. The evolution of HS reflected the imposed starting strategy, with a reduction in PO following a fast-start, an increased PO following a slow-start with similar HS during the last part of all TTs. The summated HS was strongly correlated with the sRPE of the TTs (r = 0.88). The summated HS was higher with a fast start, indicating greater effort, with limited time advantage. Thus, the HS appears to regulate both PO within a TT, but also the overall impression of the difficulty of a TT.

The session rating of perceived exertion (sRPE) method was developed 25 years ago as a modification of the Borg concept of rating of perceived exertion (RPE), designed to estimate the intensity of an entire training session. It appears to be well accepted as a marker of the internal training load. Early studies demonstrated that sRPE correlated well with objective measures of internal training load, such as the percentage of heart rate reserve and blood lactate concentration. It has been shown to be useful in a wide variety of exercise activities ranging from aerobic to resistance to games. It has also been shown to be useful in populations ranging from patients to elite athletes. The sRPE is a reasonable measure of the average RPE acquired across an exercise session. Originally designed to be acquired ∼30 minutes after a training bout to prevent the terminal elements of an exercise session from unduly influencing the rating, sRPE has been shown to be temporally robust across periods ranging from 1 minute to 14 days following an exercise session. Within the training impulse concept, sRPE, or other indices derived from sRPE, has been shown to be able to account for both positive and negative training outcomes and has contributed to our understanding of how training is periodized to optimize training outcomes and to understand maladaptations such as overtraining syndrome. The sRPE as a method of monitoring training has the advantage of extreme simplicity. While it is not ideal for the precise recording of the details of the external training load, it has large advantages relative to evaluating the internal training load.

The Talk Test (TT) has been shown to be a surrogate of the ventilatory threshold and to be a viable alternative to standard methods of prescribing exercise training intensity. The TT has also been shown to be responsive to manipulations known to change physiologic function including blood donation and training. Whether the TT can be used independently to regulated training intensity is not known. Physically active volunteers (N = 16) performed an incremental exercise test to identify stages of the TT (Last Positive [LP], Equivocal [EQ], and Negative [NEG]). In subsequent, randomly ordered, 30-minute steady-state runs, the running velocity was regulated solely by "clamping" the TT response desired and then monitoring the response of conventional markers of exercise intensity (heart rate, blood lactate, rating of perceived exertion). All subjects were able to complete the LP stage, but only 13 of 16 and 2 of 16 subjects were able to complete the EQ and NEG stages, respectively. Physiologic responses were broadly within those predicted from the incremental exercise test and within the appropriate range of physiologic responses for exercise training. Thus, in addition to correlating with convenient physiological markers, the TT can be used proactively to guide exercise training intensity. The LP stage produced training intensities compatible with appropriate training intensity in healthy adults and with recovery sessions or long duration training sessions in athletes. The EQ and NEG stages produced intensities compatible with higher intensity training in athletes. The results demonstrate that the TT can be used as a primary method to control exercise training intensity.

Previous studies have found decreases in arterial oxygen saturation to be temporally linked to reductions in power output (PO) during time-trial (TT) exercise. The purpose of this study was to determine whether preexercise desaturation (estimated from pulse oximetry [SpO2]), via normobaric hypoxia, would change the pattern of PO during a TT.Purpose:The authors tested the hypothesis that the starting PO of a TT would be reduced in the EARLY trial secondary to a reduced SpO2 but would not be reduced in LATE until ~30 s after the start of the TT.Methods:Eight trained cyclists/triathletes (4 male, 4 female) performed 3 randomly ordered 3-km TTs while breathing either room air (CONTROL) or hypoxic air administered 3 min before the start of the TT (EARLY) or at the beginning of the TT (LATE).Results:There was no effect of hypoxia on PO during the first 0.3 km of either the EARLY or the LATE trial compared with CONTROL, although there was a significant decrease in pre-TT SpO2 in EARLY vs CONTROL and LATE. The time for PO to decrease was ~40 s after the start of the TT in both EARLY and LATE.Conclusions:The results support the strong effect of the preexercise template on the pattern of PO during simulated competition and suggest that reductions in SpO2 are not direct signals to decrease PO.

Concepts of how athletes should expend their aerobic and anaerobic energetic reserves are generally based on results of tests where an "all out" strategy is imposed on/required from the athlete. We sought to determine how athletes spontaneously expend their energetic reserves when the only instruction was to finish the event in minimal time, as in competition. Well trained, and task habituated, road cyclists (N = 14) completed randomly ordered laboratory time trials of 500 m, 1000 m, 1500 m and 3000 m on a windload braked cycle ergometer. The pattern of aerobic and anaerobic energy use was calculated from total work accomplished and V.O (2) during the trials. The events were completed in 40.3 +/- 0.6 s, 87.4 +/- 4.1 s, 133.8 +/- 6.6 s and 296.0 +/- 7.2 s. The peak V.O (2) during the terminal 200 m of all events was similar (2.72 +/- 0.22, 3.01 +/- 0.34, 3.23 +/- 0.44 and 3.12 +/- 0.13 l x min (-1)). In all events, the initial power output and anaerobic energy use was high, and decreased to a more or less constant value over the remainder of the event. However, the subjects seemed to reserve some ability to expend energy anaerobically for a terminal acceleration which is contrary to predictions of an "all out" starting strategy. Although the total work accomplished increased with distance (23.14 +/- 4.24, 34.14 +/- 6.37, 43.54 +/- 6.12 and 78.22 +/- 8.28 kJ), the energy attributable to anaerobic sources was not significantly different between the rides (17.29 +/- 3.82, 18.68 +/- 8.51, 20.60 +/- 6.99 and 23.28 +/- 9.04 kJ). The results are consistent with the concept that athletes monitor their energetic resources and regulate their energetic output over time in a manner designed to optimize performance.

Purpose:To reach top performance in cycling, optimizing distribution of energy resources is crucial. The purpose of this study was to investigate power output during 250-m, 500-m, and 1000-m cycling time trials and the characteristics of the adopted pacing strategy.Methods:Nine trained cyclists completed an incremental test and 3 time trials that they were instructed to finish as quickly as possible. Preceding the trials, peak power during short sprints (PPsprint) and gross efficiency (GE) were measured. During the trials, power output and oxygen consumption were measured to calculate the contribution of the aerobic and anaerobic energy sources. After the trial GE was measured again.Results:Peak power during all trials (PPTT) was lower than PPsprint. In the 250-m trial the PPTT was higher in the 1000-m trial (P = .008). The subjects performed a significantly longer time at high intensity in the 250-m than in the 1000-m (P = .029). GE declined significantly during all trials (P < .01). Total anaerobically attributable work was less in the 250-m than in the 500-m (P = .015) and 1000-m (P < .01) trials.Conclusion:The overall pacing pattern in the 250-m trial appears to follow an all-out strategy, although peak power is still lower than the potential maximal power output. This suggests that a true all-out pattern of power output may not be used in fixed-distance events. The 500-m and 1000-m had a more conservative pacing pattern and anaerobic power output reached a constant magnitude.

The ability to monitor training is critical to the process of quantitating training periodization plans. To date, no method has proven successful in monitoring training during multiple types of exercise. High-intensity exercise training is particularly difficult to quantitate. In this study we evaluate the ability of the session rating of perceived exertion (RPE) method to quantitate training during non-steady state and prolonged exercise compared with an objective standard based on heart rate (HR). In a 2-part design, subjects performed steady state and interval cycle exercise or practiced basketball. Exercise bouts were quantitated using both the session RPE method and an objective HR method. During cycle exercise, the relationship between the exercise score derived using the session RPE method and the HR method was highly consistent, although the absolute score was significantly greater with the session RPE method. During basketball, there was a consistent relationship between the 2 methods of monitoring exercise, although the absolute score was also significantly greater with the session RPE method. Despite using different subjects in the 2 parts of the study, the regression relationships between the session RPE method and the HR method were nearly overlapping, suggesting the broad applicability of this method. We conclude that the session RPE method is a valid method of quantitating exercise training during a wide variety of types of exercise. As such, this technique may hold promise as a mode and intensity-independent method of quantitating exercise training and may provide a tool to allow the quantitative evaluation of training periodization plans.

The winter 1991 issue of Reference Services Review featured an annotated bibliography of literature on Christopher Columbus from 1970 to 1989. That literature covered such topics as Columbus' ancestry, heraldry, and the locations of both his American landfall and burial site. This annotated checklist focuses mainly on Columbus' legacy, on works that offer a dissenting point of view from most previous writings about Columbus (and on works that react to the dissenters), on material written by Native American and other non‐European authors, and on materials published by small and noncommercial presses.

The ability to modify power output (PO) in response to a changing stimulus during exercise is crucial for optimizing performance involving an integration system involving a performance template and feedback from peripheral receptors. The rapidity with which PO is modified has not been established, but would be of interest relative to understanding how PO is regulated. The objective is to determine the rapidity of changes in PO in response to a hypoxic challenge, and if change in PO is linked to changes in arterial O2 saturation (S aO2). Well-trained cyclists performed randomly ordered 5-km time trials. Subjects began the trials breathing room air and switched to hypoxic (HYPOXIC, FIO2 = 0.15) or room (CONTROL, FIO2 = 0.21) air at 2 km, then to room air at 4 km. The time delay to begin decreasing S aO2 and PO and to recover S aO2 and PO on to room air was compared, along with the half time (t 1/2) during the HYPOXIC trial. Mean S aO2 and PO between 2 and 4 km were significantly different between CONTROL and HYPOXIC (94 ± 2 vs. 83 ± 2% and 285 ± 16 vs. 245 ± 19 W, respectively). There was no difference between the time delay for S aO2 (31.5 ± 12.8 s) and in PO (25.8 ± 14.4 s) or the recovery of S aO2 (29.0 ± 7.7 s) and PO (21.5 ± 12.4 s). The half time for decreases in S aO2 (56.6 ± 14.4 s) and in PO (62.7 ± 20.8 s) was not significantly different. Modifications of PO due to the abrupt administration of hypoxic air are related to the development of arterial hypoxemia, and begin within ~30 s.

BACKGROUND: Previous studies suggest that the rating of perceived exertion (RPE) increases during steady-state, open-loop exercise in proportion to the relative time to fatigue. This suggests that RPE is scalar and integrates physiological status and homeostatic disturbances. PURPOSE: This study assessed the relationship between the rate of change in RPE, and relative distance in time trials at distances of 2.5, 5, and 10 km. It also assessed the rate of change in RPE during 5-km time trials while breathing hypoxic air. METHODS: The subjects were well-conditioned cyclists. In part 1, each subject completed habituation time trials, and then randomly ordered time trials at each distance. The category ratio RPE was measured in 10% increments throughout each trial. In part 2, each subject completed three 5-km time trials while breathing different inspired gas mixtures (FiO2 = 0.2093 throughout the trial, FiO2 = 0.15 between 2 and 4 km, and FiO2 = 0.15 between 2.5 and 4 km). RPE was measured at 10% increments. RESULTS: In part 1, when RPE was plotted against relative distance, there was no significant difference in the growth of RPE at proportional distances. In part 2, the decrease in power output during the hypoxic segments was sufficient that the growth of RPE was the same at each proportional distance. In both parts of the study, an RPE of 5 (hard) was achieved after 20% of the time trial distance, and an RPE of 8 was achieved after 80% distance. CONCLUSIONS: This study supports the hypothesis that RPE increases similarly in relation to relative distance, regardless of the distance performed, and it suggests that the perception of effort has scalar properties. ©2008The American College of Sports Medicine.

FOSTER, C., J. J. DE KONING, F. HETTINGA, J. LAMPEN, K. L. LA CLAIR, C. DODGE, M. BOBBERT, and J. P. PORCARI. Pattern of Energy Expenditure during Simulated Competition. Med. Sci. Sports Exerc., Vol. 35, No. 5, pp. 826 – 831, 2003. Purpose: To determine how athletes spontaneously use their energetic reserves when the only instruction was to finish in minimal time, and whether experience from repeated performance changes the strategy of recreational athletes. Methods: Recreational road cyclists/speed skaters (N 9) completed three laboratory time trials of 1500 m on a windload braked cycle. The pattern of energy use was calculated from total work and from the work attributable to aerobic metabolism, which allowed computation of anaerobic energy use. Regional level speed skaters (N 8) also performed a single 1500-m time trial with the same protocol and measurements. Results: The serial trials were completed in (mean SD) 133.8 6.6, 133.9 5.8, 133.8 5.5 s( P 0.05 among trials); and in 125.7 10.9 s in the skaters (P 0.05 vs cyclists). The V u O2peak during the terminal 200 m was similar within trials (3.23 0.44, 3.34 0.44, 3.30 0.51 (P 0.05)) versus 3.91 0.68 L·min 1 in the skaters (P 0.05 vs cyclists). In all events, the initial power output and anaerobic energy use was high and decayed to a more or less constant value (~25% of peak) over the remainder of the event. Contrary to predictions based on an assumed “all out” starting strategy, the subjects reserved some of their ability to perform anaerobic work for a terminal acceleration. The total work accomplished was not different between trials (43.53, 43.78, and 47.48 kJ in the recreational athletes, or between the cyclists and skaters (47.79 kJ). The work attributable to anaerobic sources was not different between the rides (20.67, 20.53, and 21.12 kJ in the recreational athletes). In the skaters, the work attributable to anaerobic sources was significantly larger versus the cyclists (24.67 kJ). Conclusion: Energy expenditure during high-intensity cycling seems: 1) to be expended in a manner that allows the athlete to preserve an anaerobic energetic contribution throughout an event, 2) does not appear to have a large learning effect in already well trained cyclists, and 3) anaerobic energy expenditure may be the performance discriminating factor among groups of

An in vitro biochemical fuel cell based upon the enzymatically catalyzed aerobic oxidation of glucose is described. The anodic half-reaction employs an electron transfer sequence consisting of the glucose oxidase reductive half-reaction and dichloroindophenol. The cathodic half-reaction involves reduction of molecular oxygen. A high Faradic efficiency for the intact cell approaching 100% has been experimentally demonstrated. The steady state current is exponentially related to the concentration of the terminal electron transfer species in the anodic chamber. The behavior is consistent with application of the Nernst relationship to define the cell potential and a simple resistance circuit. The discharge profile of the cell after complete oxidation of the primary fuel, glucose, can be modeled as a capacitor discharging through a resistor.