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[English] Four elite rowers completed a 12-day altitude training camp living at 1800 m, and training at 1800 m and 915 m, to assess changes in resting metabolic rate (RMR). RMR and body composition were assessed pre- and post camp. Downward trends in RMR and body composition were observed post altitude: absolute RMR (percent change: –5.2%), relative RMR (–4.6%), body mass (–1.2%), and fat mass (–4.1%). These variations are likely related to the hypoxic stimulus and an imbalance between training load and energy intake. [French] Quatre rameurs d’élite participent à un camp d’entraînement en altitude d’une durée de 12 jours; ils demeurent à une altitude de 1800 m et s’entraînent à cette altitude ainsi qu’à 915 m. Avant et après le camp d’entraînement, on mesure le métabolisme de repos (« RMR ») et la composition corporelle. Après le camp, on observe une tendance à la baisse du RMR et de la composition corporelle : RMR absolu (variation en pourcentage : –5,2 %), RMR relatif (–4,6 %), masse corporelle (–1,2 %) et masse adipeuse (–4,1 %). Ces variations sont vraisemblablement associées au stimulus de l’hypoxie et au déséquilibre entre la charge d’entraînement et l’apport énergétique. [Traduit par la Rédaction]

Purpose:To investigate changes in physiology, performance, and training practices of elite Australian rowers over 6 mo.Methods:Twenty-one elite rowers (14 male, 7 female) were monitored throughout 2 phases: phase 1 (specific preparation) and phase 2 (domestic competition). Incremental tests and rowing-ergometer time trials over 100, 500, 2000, and 6000 m were conducted at the start of the season, midseason, and late season. Weekly external (frequency, duration, distance rowed) and internal (T2minute method) loads are reported.Results:Heavyweight male rowers achieved moderate improvements in VO2max and power at VO2max. Most other changes in physiology and performance were small or unclear. External loads decreased from phase 1 to phase 2 (duration 19.3 to 18.0 h/wk, distance rowed 140 to 125 km/wk, respectively). Conversely, internal loads increased (phase 1 = 19.0 T2hours, phase 2 = 20.3 T2hours). Low-intensity training predominated (~80% of training hours at T1 and T2), and high-intensity training was greater in phase 2. Training was rowing-focused (68% of training duration), although 32% of training time was spent in nonspecific modes. The distribution of specificity was not different between phases.Conclusion:Physiology and performance results were stable over the 6-mo period. Training-load patterns differed depending on the measure, highlighting the importance of monitoring both external and internal loads. The distribution of intensity was somewhat polarized, and substantial volumes of nonspecific training were undertaken. Experimental studies should investigate the effects of different distributions of intensity and specificity on rowing performance.

The majority of lightweight rowers undertake acute weight loss prior to competition. Given the competitive advantage afforded to larger, more muscular rowers over their smaller counterparts, the use of moderate, acute weight loss may be justified, at least among larger, leaner athletes who struggle to achieve the specified body mass requirement and have limited potential for further body mass loss via reductions in body fat. The performance implications of moderate acute weight loss appear to be small on the ergometer and may be even less on water, at least when aggressive recovery strategies are adopted between weigh-in and racing. Furthermore, any performance implications of acute weight loss are not exacerbated when such weight loss is undertaken repeatedly throughout the course of a regatta, and may even be eliminated when aggressive recovery strategies are introduced before and after racing. The combination of adequate sodium, fluid and carbohydrate in line with current guidelines results in the best performances. While the performance implications of modest acute weight loss may still need to be considered in regard to competition outcome, chronic body mass strategies may not be without performance implications. This is especially the case for athletes who have very low levels of body fat and/or athletes who decrease their body mass too quickly. Further studies are needed to address the degree of weight loss that can be tolerated with minimal health and/or performance implications, and the optimal time frame over which this should occur. Possible adaptation to the physiological state that accompanies acute weight loss also warrants investigation.

The systematic management of training requires accurate training load measurement. However, quantifying the training of elite Australian rowers is challenging because of (a) the multicenter, multistate structure of the national program; (b) the variety of training undertaken; and (c) the limitations of existing methods for quantifying the loads accumulated from varied training formats. Therefore, the purpose of this project was to develop a new measure for quantifying training loads in rowing (the T2minute method). Sport scientists and senior coaches at the National Rowing Center of Excellence collaborated to develop the measure, which incorporates training duration, intensity, and mode to quantify a single index of training load. To account for training at different intensities, the method uses standardized intensity zones (T zones) established at the Australian Institute of Sport. Each zone was assigned a weighting factor according to the curvilinear relationship between power output and blood lactate response. Each training mode was assigned a weighting factor based on whether coaches perceived it to be "harder" or "easier" than on-water rowing. A common measurement unit, the T2minute, was defined to normalize sessions in different modes to a single index of load; one T2minute is equivalent to 1 minute of on-water single scull rowing at T2 intensity (approximately 60-72% VO2max). The T2minute method was successfully implemented to support national training strategies in Australian high performance rowing. By incorporating duration, intensity, and mode, the T2minute method extends the concepts that underpin current load measures, providing 1 consistent system to quantify loads from varied training formats.

High altitude exposure can increase resting metabolic rate (RMR) and induce weight loss in obese populations, but there is a lack of research regarding RMR in athletes at moderate elevations common to endurance training camps. The present study aimed to determine whether 4 weeks of classical altitude training affects RMR in middle-distance runners. Ten highly trained athletes were recruited for 4 weeks of endurance training undertaking identical programs at either 2200m in Flagstaff, Arizona (ALT, n = 5) or 600m in Canberra, Australia (CON, n = 5). RMR, anthropometry, energy intake, and hemoglobin mass (Hbmass) were assessed pre- and posttraining. Weekly run distance during the training block was: ALT 96.8 ± 18.3km; CON 103.1 ± 5.6km. A significant interaction for Time*Group was observed for absolute (kJ.day-1) (F-statistic, p-value: F(1,8)=13.890, p = .01) and relative RMR (F(1,8)=653.453, p = .003) POST-training. No significant changes in anthropometry were observed in either group. Energy intake was unchanged (mean ± SD of difference, ALT: 195 ± 3921kJ, p = .25; CON: 836 ± 7535kJ, p = .75). A significant main effect for time was demonstrated for total Hbmass (g) (F(1,8)=13.380, p = .01), but no significant interactions were observed for either variable [Total Hbmass (g): F(1,8)=1.706, p = .23; Relative Hbmass (g.kg-1): F(1,8)=0.609, p = .46]. These novel findings have important practical application to endurance athletes routinely training at moderate altitude, and those seeking to optimize energy management without compromising training adaptation. Altitude exposure may increase RMR and enhance training adaptation,. During training camps at moderate altitude, an increased energy intake is likely required to support an increased RMR and provide sufficient energy for training and performance.

The aim of the current study was to determine if a single ParvoMedics TrueOne 2400 metabolic cart provides valid and reliable measurement of RMR in comparison with the criterion Douglas Bag method (DB). Ten endurance-trained participants completed duplicate RMR measurements on 2 consecutive days using the ParvoMedics system in exercise mode, with the same expirate analyzed using DB. Typical error (TE) in mean RMR between the systems was 578.9 kJ or 7.5% (p = .01). In comparison with DB, the ParvoMedics system over-estimated RMR by 946.7 ± 818.6 kJ. The bias between systems resulted from ParvoMedics VE(STPD) values. A regression equation was developed to correct the bias, which reduced the difference to -83.3 ± 631.9 kJ. TE for the corrected ParvoMedics data were 446.8 kJ or 7.2% (p = .70). On Day 1, intraday reliability in mean RMR for DB was 286.8 kJ or 4.3%, (p = .54) and for ParvoMedicsuncorrected, 359.3 kJ or 4.4%, (p = .35), with closer agreement observed on Day 2. Interday reliability for DB was 455.3 kJ or 6.6% (p = .61) and for ParvoMedicsuncorrected, 390.2 kJ or 6.3% (p = .54). Similar intraday and interday TE was observed between ParvoMedicsuncorrected and ParvoMedicscorrected data. The ParvoMedics TrueOne 2400 provided valid and reliable RMR values compared with DB when the VE(STPD) error was corrected. This will enable widespread monitoring of RMR using the ParvoMedics system in a range of field-based settings when DB is not available.

Rowing requires strength, power, and strength-endurance for optimal performance. A rowing-based warm-up could be enhanced by exploiting the postactivation potentiation (PAP) phenomenon, acutely enhancing power output at the beginning of a race where it is needed most. Minimal research has investigated the effects of PAP on events of longer duration (i.e. 1,000-m rowing). The purpose of this research was to investigate the effects of PAP on 1,000-m rowing ergometer performance through the use of 2 different warm-up procedures: (a) a rowing warm-up combined with a series of isometric conditioning contractions, known as the potentiated warm-up (PW), and (b) a rowing warm-up only (NW). The isometric conditioning contractions in the PW were performed by "pulling" an immovable handle on the rowing ergometer, consisting of 5 sets of 5 seconds (2 seconds at submaximal intensity, and 3 seconds at maximal intensity), with a 15-second recovery between sets. The 1,000-m rowing ergometer time trial was performed after each warm-up condition, whereby mean power output, mean stroke rate, and split time were assessed every 100 m. Ten Australian national level rowers served as the subjects and performed both conditions in a counterbalanced order on separate days. The PW reduced 1,000-m time by 0.8% (p > 0.05). The PW improved mean power output by 6.6% (p < 0.01) and mean stroke rate by 5.2% (p < 0.01) over the first 500 m; resulting in a reduction of 500-m time by 1.9% (p < 0.01), compared with the NW. It appears that the inclusion of isometric conditioning contractions to the rowing warm-up enhance short-term rowing ergometer performance (especially at the start of a race) to a greater extent than a rowing warm-up alone.

Purpose:The Concept II model C (IIC) rowing ergometer was replaced by the Concept II model D (IID), but the design modifications of the updated ergometer might alter resistance characteristics and rowing technique, thereby potentially influencing ergometer test results. This study evaluated the physiological response to rowing on the IIC and IID ergometers during a submaximal progressive incremental test and maximal-performance time trial.Methods:Eight national-level rowers completed submaximal and maximal tests on the IIC and IID ergometers separated by 48 to 72 h. Physiological responses and calculated blood lactate thresholds (LT1 and LT2) were compared between ergometer models (IIC vs IID) using standardized drag-factor settings.Results:Power output, oxygen consumption, rowing economy (mL O2 · min−1 · W−1), heart rate, blood lactate concentration, stroke rate, and rating of perceived exertion all displayed similar responses regardless of ergometer model. Calculated physiological values equivalent to LT1 and LT2 were also similar between models, except for blood lactate concentration at LT1, which displayed a small but statistically signifcant difference (P = .02) of 0.2 mmol/L.Conclusions:The physiological response when rowing on IIC and IID ergometers is nearly identical, and testing can therefore be carried out on either ergometer and the results directly compared.

Objectives: Physique traits and their relationship to competitive success were assessed amongst lightweight rowers competing at the 2003 Australian Rowing Championships. Methods: Full anthropometric profiles were collected from 107 lightweight rowers (n = 65 males, n = 45 females) competing in the Under 23 and Open age categories. Performance assessments were obtained for 66 of these rowers based on results in the single sculls events. The relationship between physique traits and competitive success was then determined. Results: Lower body fat ( heat time estimate -8.4 s kg(-1), p< 0.01), greater total body mass ( heat time estimate -4.4 s kg(-1), p = 0.03), and muscle mass ( heat time estimate -10.2 s kg(-1), p< 0.01) were associated with faster 2000 m heat times. Conclusions: The more successful lightweight rowers were those who had lower body fat and greater total muscle mass.

Background Recent research has demonstrated decreases in resting metabolic rate (RMR), body composition and performance following a period of intensified training in elite athletes, however the underlying mechanisms of change remain unclear. Therefore, the aim of the present study was to investigate how an intensified training period, designed to elicit overreaching, affects RMR, body composition, and performance in trained endurance athletes, and to elucidate underlying mechanisms. Method Thirteen (n = 13) trained male cyclists completed a six-week training program consisting of a “Baseline” week (100% of regular training load), a “Build” week (~120% of Baseline load), two “Loading” weeks (~140, 150% of Baseline load, respectively) and two “Recovery” weeks (~80% of Baseline load). Training comprised of a combination of laboratory based interval sessions and on-road cycling. RMR, body composition, energy intake, appetite, heart rate variability (HRV), cycling performance, biochemical markers and mood responses were assessed at multiple time points throughout the six-week period. Data were analysed using a linear mixed modeling approach. Results The intensified training period elicited significant decreases in RMR (F(5,123.36) = 12.0947, p =

Elite rowers complete rowing-specific and non-specific training, incorporating continuous and interval-like efforts spanning the intensity spectrum. However, established training load measures are unsuitable for use in some modes and intensities. Consequently, a new measure known as the T2minute method was created. The method quantifies load as the time spent in a range of training zones (time-in-zone), multiplied by intensity- and mode-specific weighting factors that scale the relative stress of different intensities and modes to the demands of on-water rowing. The purpose of this study was to examine the convergent validity of the T2minute method with Banister's training impulse (TRIMP), Lucia's TRIMP and Session-RPE when quantifying elite rowing training. Fourteen elite rowers (12 males, 2 females) were monitored during four weeks of routine training. Unadjusted T2minute loads (using coaches' estimates of time-in-zone) demonstrated moderate-to-strong correlations with Banister's TRIMP, Lucia's TRIMP and Session-RPE (rho: 0.58, 0.55 and 0.42, respectively). Adjusting T2minute loads by using actual time-in-zone data resulted in stronger correlations between the T2minute method and Banister's TRIMP and Lucia's TRIMP (rho: 0.85 and 0.81, respectively). The T2minute method is an appropriate in-field measure of elite rowing training loads, particularly when actual time-in-zone values are used to quantify load.

A group of 15 competitive male cyclists [mean peak oxygen uptake, V˙O2peak 68.5 (SEM 1.5 ml · kg−1 · min−1)] exercised on a cycle ergometer in a protocol which began at an intensity of 150 W and was increased by 25 W every 2 min until the subject was exhausted. Blood samples were taken from the radial artery at the end of each exercise intensity to determine the partial pressures of blood gases and oxyhaemoglobin saturation (S aO2), with all values corrected for rectal temperature. The S a O2 was also monitored continuously by ear oximetry. A significant decrease in the partial pressure of oxygen in arterial blood (P aO2) was seen at the first exercise intensity (150 W, about 40% V˙O2peak). A further significant decrease in P aO2 occurred at 200 W, whereafter it remained stable but still significantly below the values at rest, with the lowest value being measured at 350 W [87.0 (SEM 1.9) mmHg]. The partial pressure of carbon dioxide in arterial blood (P aCO2) was unchanged up to an exercise intensity of 250 W whereafter it exhibited a significant downward trend to reach its lowest value at an exercise intensity of 375 W [34.5 (SEM 0.5) mmHg]. During both the first (150 W) and final exercise intensities (V˙O2peak) P aO2 was correlated significantly with both partial pressure of oxygen in alveolar gas (P AO2, r = 0.81 and r = 0.70, respectively) and alveolar-arterial difference in oxygen partial pressure (P A−aO2, r = 0.63 and r = 0.86, respectively) but not with P aCO2. At V˙O2peak P aO2 was significantly correlated with the ventilatory equivalents for both oxygen uptake and carbon dioxide output (r = 0.58 and r = 0.53, respectively). When both P AO2 and P A−aO2 were combined in a multiple linear regression model, at least 95% of the variance in P aO2 could be explained at both 150 W and V˙O2peak. A significant downward trend in S aO2 was seen with increasing exercise intensity with the lowest value at 375 W [94.6 (SEM 0.3)%]. Oximetry estimates of S aO2 were significantly higher than blood measurements at all times throughout exercise and no significant decrease from rest was seen until 350 W. The significant correlations between P aO2 and P AO2 with the first exercise intensity and at V˙O2peak led to the conclusion that inadequatehyperventilation is a major contributor to exercise-induced hypoxaemia.

Haemoglobin mass (Hb mass), maximum oxygen consumption (VO 2max ), simulated 4000 m individual pursuit cycling performance (IP 4000 ), and haematological markers of red blood cell (RBC) turnover were measured in 8 male cyclists before and after (A) 31 d of altitude training at 2690 m. The dependent variables were measured serially after altitude on d A3-4, A8-9 and A20-21. There was no significant change in Hb mass over the course of the study and VO 2max at d A9 was significantly lower than the baseline value (79.3 ± 0.7 versus 81.4 ± 0.6 ml.kg −1 .min −1 , respectively). No increase in Hb mass or VO 2max was probably due to initial values being close to the natural physiological limit with little scope for further change. When the IP 4000 was analysed as a function of the best score on any of the three test days after altitude training there was a 4% improvement that was not reflected in a corresponding change in VO 2max or Hb mass. RBC creatine concentration was significantly reduced after altitude training, suggesting a decrease in the average age of the RBC population. However, measurement of reticulocyte number and serum concentrations of erythropoietin, haptoglobin and bilirubin before and after altitude provided no evidence of increased RBC turnover. The data suggest that for these elite cyclists any benefit of altitude training was not from changes in VO 2max or Hb mass, although this does not exclude the possibility of improved anaerobic capacity.

Purpose:This study evaluated the validity of ergometer tests against the criterion of on-water rowing and determined the reliability of feld measurements by comparing results between ergometer (ERG) and on-water (OW) tests.Methods:Seven male rowers completed incremental tests on a Concept2 rowing ergometer and in a single scull. Average power output, oxygen consumption (VO2), heart rate (HR), blood lactate concentration (BLa) and distance completed were measured during each ERG and OW workload.Data treatment:Linear regression between power output and HR, BLa, VO2 and distance allowed submaximal results to be compared between ERG and OW tests at equivalent intensities based on five standard power outputs. Submaximal results were analyzed using repeated measure factorial ANOVAs and maximal data used dependent t tests (P < .05), the magnitude of differences were also classified using effect size analyses. The reliability of repeated measurements was established using Typical Error.Results:Differences between ERG and OW submaximal results were not statistically significant for power output, HR, BLa, and VO2, but distance completed (P < .001) was higher during the ERG test. However, the magnitude of physiological response differences between the ERG and OW tests varied between individuals. Mean HR at anaerobic threshold showed good agreement between both tests (r = .81), but the standard error of the estimate was 9 beats per minute.Conclusions:Individual variation in physiological response differences between ERG and OW tests meant that training intensity recommendations from the ERG test were not applicable to on-water training for some rowers, but provided appropriate prescriptions for most athletes.

Portable indirect calorimetry systems offer the advantage of field-based measurements, but manufacturers rarely provide data about validity or reliability. In this study, we evaluated the validity and reliability of the Cortex MetaMax3B portable metabolic system. Validity was determined by comparing MetaMax3B results against those from a first-principles metabolic calibrator and an automated Douglas bag system. Reliability was obtained from duplicate exercise tests completed by eight athletes. Participants completed three identical incremental rowing tests on a Concept2 ergometer; two tests used the MetaMax3B and one test used the Douglas bag system. Compared with the metabolic calibrator, the MetaMax3B results were within 0.20 litres . min(-1) (7.8%) and 6.15 litres . min(-1) (4.0%) for [Vdot]O(2) and V(E), respectively. During exercise, the MetaMax3B results were within 0.16 litres . min(-1) (4.1%; [Vdot]O(2)), 0.32 litres . min(-1) (7.7%; [Vdot]CO(2)), and 3.22 litres . min(-1) (4.9%; V(E)) compared with the Douglas bag system. The MetaMax3B results were significantly higher for [Vdot]O(2) (P = 0.03) and [Vdot]CO(2) (P0.001). The typical error from duplicate exercise tests using the MetaMax3B ranged from 2.0% ([Vdot]O(2)) to 3.6% (V(E)). Our results show that the MetaMax3B provides reliable measurements of metabolic demand with adequate validity for field-based measurements.

SLATER, G. J., A. J. RICE, K. SHARPE, D. JENKINS, and A. G. HAHN. Influence of Nutrient Intake after Weigh-In on Lightweight Rowing Performance. Med. Sci. Sports Exerc., Vol. 39, No. 1, pp. 184–191, 2007. Purpose: The aim of the present study was to compare the effectiveness of different nutritional recovery strategies between weigh-in and racing on 2000-m rowing ergometer performance among oarsmen undertaking short-term weight loss before competition. Methods: Competitive rowers (N = 12) completed four ergometer trials, each separated by 48 h. No weight restrictions were imposed for the first trial (TR1). Thereafter, athletes were required to reduce their body mass by 5.2% in the 24 h before trial 2 (TR2), again reaching this body mass before the final two trials (TR3 and TR4). Athletes were provided with one of three nutritional recovery strategies in the 2 h between weighin and racing in a counterbalanced fashion according to a Latin square design: fluid (2.8 kJIkg j1 , 0.0 gIkg j1 carbohydrate, 0.6 mgIkg j1 sodium, 28.5 mLIkg j1 fluid; FLU), carbohydrate/sodium (45.3 kJIkg j1 , 2.2 gIkg j1 carbohydrate, 32.9 mgIkg j1 sodium, 7.2 mLIkg j1 fluid; CHO), and a combination of water and carbohydrate/sodium (44.8 kJIkg j1 , 2.3 gIkg j1 carbohydrate, 33 mgIkg j1 sodium, 28.5 mLIkg j1 fluid; COM). Results: Performance was slower for CHO compared with both COM (mean difference, 4.13; 95% CI, 1.37–6.88 s; P = 0.003) and FLU (2.88; 95% CI, 0.13–5.63 s; P = 0.039). However, FLU was not significantly slower than COM (1.24; 95% CI, j1.41 to 3.90 s; P = 0.474). Conclusions: The present investigation has shown that although carbohydrate and sodium intake may be important in the recovery period between weigh-in and 2000-m rowing ergometer performance, fluid intake has a greater influence on performance among lightweight male rowers who undertake short-term weight loss to achieve specified

To strengthen the depth of lightweight rowing talent, we sought to identify experienced heavyweight rowers who possessed physique traits that predisposed them to excellence as a lightweight. Identified athletes (n = 3) were monitored over 16 wk. Variables measured included performance, anthropometric indices, and selected biochemical and metabolic parameters. All athletes decreased their body mass (range 2.0 to 8.0 kg), with muscle mass accounting for a large proportion of this (31.7 to 84.6%). Two athletes were able to maintain their performance despite reductions in body mass. However, performance was compromised for the athlete who experienced the greatest weight loss. In summary, smaller heavyweight rowers can successfully make the transition into the lightweight category, being nationally competitive in their first season as a lightweight.

OBJECTIVE These studies were conducted to test the hypothesis that isobaric hypoxia would switch OSA to central sleep apnoea (CSA). METHODS Five adult men (mean age 54.2 +/- 5.5 years, mean BMI 29.9 +/- 6.7 kg/m(2)) with moderate OSA underwent overnight polysomnography at three altitudes. The highest altitude was simulated in a normobaric hypoxic chamber. RESULTS The obstructive respiratory disturbance index fell from 25.5 +/- 14.4/h at 60 m to 17.3 +/- 9.2/h at 610 m and 0.5 +/- 0.7/h at 2750 m (P = 0.004 compared with 60 m). The central respiratory disturbance index rose from 0.4 +/- 0.5/h at 60 m to 8.1 +/- 5.8/h at 610 m and 78.8 +/- 29.7/h at 2750 m (P < 0.001 compared with 60 m). Mean sleep SaO(2) fell from 94 +/- 1% at 60 m to 93 +/- 1% at 610 m to 85 +/- 4% at 2750 m (P < 0.001 compared with 60 m). CONCLUSION Moderate severity OSA at sea level (60 m) was completely replaced by severe CSA at a simulated altitude of 2750 m. The authors believe that the OSA resolved because of an increased respiratory drive [corrected] and an increase in upper airway tone, whereas CSA developed because of hypocapnia in non-rapid eye movement sleep.

Purpose: The present study was conducted to examine the impact of acute weight loss on repeat 2000-m rowing ergometer performance during a simulated multiday regatta. and to compare two different body mass management strategies between races. Methods: Competitive rowers (N = 16) were assigned to either a control (CON), partial recovery (RECpartial), or complete recovery (RECcomplete) group. Volunteers completed four trials, each separated by 48 h. No weight restrictions were imposed for the first trial. Thereafter, athletes in RECpartial and RECcomplete were required to reduce their body mass by 4% in the 24 h before trial 2, again reaching this body mass before the final two trials. No weight restrictions were imposed on CON. Aggressive nutritional recovery strategies were used in the 2 h following weigh-in for all athletes. These strategies were maintained for the 12-16 h following racing for RECcomplete with the aim of restoring at least three quarters of the original 4% body mass loss. Postrace recovery strategies were less aggressive in RECpartial; volunteers were encouraged to restore no more than half of their initial 4% body mass loss. Results: Acute weight loss increased time to complete the first at-weight performance trial by a small margin (mean 3.0, 95% CI -0.3 to 6.3 s, P = 0.07) when compared with the CON response. This effect decreased when sustained for several day,. Aggressive postrace recovery strategies tended to eliminate the effect of acute Weight loss on subsequent performance. Conclusion: Acute weight loss resulted in a small performance compromise that was reduced or eliminated when repeated over several days. Athletes should be encouraged to maximize recovery in the 12-16 h following racing when attempting to optimize subsequent performance.

Purpose: Although the body-mass management strategies of athletes in high-participation weight-category sports such as wrestling have been thoroughly investigated, little is known about such practices among lightweight rowers. This study examined the body-mass management practices of lightweight rowers before competition and compared these with current guidelines of the International Federation of Rowing Association (FISA). Quantification of nutrient intake in the 1-2 h between weigh-in and racing was also sought. Methods: Lightweight rowers (N = 100) competing in a national regatta completed a questionnaire that assessed body-mass management practices during the 4 wk before and throughout a regatta plus recovery strategies after weigh-in. Biochemical data were collected immediately after weigh-in to validate questionnaire responses. Responses were categorized according to gender and age category (Senior B or younger than 23 yr old, i.e., U23, Senior A or OPEN, i.e., open age limit) for competition. Results: Most athletes (male U23 76.5%, OPEN 92.3%; female U23 84.0%, OPEN 94.1%) decreased their body mass in the weeks before the regatta at rates compliant with FISA guidelines. Gradual dieting, fluid restriction, and increased training load were the most popular methods of body-mass management. Although the importance of recovery after weigh-in was recognized by athletes, nutrient intake and especially sodium (male U23 5.3 P 4.9, OPEN 7.7 P 5.9; female U23 5.7 P 6.8, OPEN 10.2 P 5.4 mg-kg(-1)) and fluid intake (male U23 12.1 P 7.1, OPEN 13.5 P 8.1; female U23 9.4 P 7.4, OPEN 14.8 P 6.9 mL.kg(-1)) were below current sports nutrition recommendations. Conclusion: Few rowers were natural lightweights; the majority reduced their body mass in the weeks before a regatta. Nutritional recovery strategies implemented by lightweight rowers after weigh-in were not consistent with current guidelines.

Central apneas occur after cessation of mechanical ventilation despite normocapnic conditions. We asked whether this was due to ventilator-induced increases in respiratory rate or VT. Accordingly, we compared the effects of increased VT (135 to 220% of eupneic VT) with and without increased respiratory rate, using controlled and assist control mechanical ventilation, respectively, upon transdiaphragmatic pressure in sleeping humans. Increasing ventilator frequency +1 per minute and VT to 165-200% of baseline eupnea eliminated transdiaphragmatic pressure during controlled mechanical ventilation and prolonged expiratory time (two to four times control) after mechanical ventilation. During and after assist control mechanical ventilation at 135-220% of eupneic VT, transdiaphragmatic pressure was reduced in proportion to the increase in ventilator volume. However, every ventilator cycle was triggered by an active inspiration, and immediately after mechanical ventilation, expiratory time during spontaneous breathing was prolonged less than 20% of that observed after controlled mechanical ventilation at similar VT. We conclude that both increased frequency and VT during mechanical ventilation significantly inhibited respiratory motor output via nonchemical mechanisms. Controlled mechanical ventilation at increased frequency plus moderate elevations in VT reset respiratory rhythm and inhibited respiratory motor output to a much greater extent than did increased VT alone.

We examined whether lung inflammatory mediators are increased during exercise and whether pharmacological blockade can prevent exercise-induced arterial hypoxemia (EIAH) in young athletes. Seventeen healthy athletes (9 men, 8 women; age 23 ± 3 yr) with varying degrees of EIAH completed maximal incremental treadmill exercise tests after administration of fexofenadine, zileuton, and nedocromil sodium or placebo in a randomized double-blind crossover study. Lung function, arterial blood gases, and inflammatory metabolites in plasma, urine, and induced sputum were assessed. Drug administration did not improve EIAH or gas exchange during exercise. At maximal exercise, oxygen saturation fell to 91.4 ± 2.6% (drug trial) and 91.9 ± 2.1% (placebo trial) and alveolar-arterial oxygen difference widened to 28.1 ± 6.3 Torr (drug trial) and 29.3 ± 5.7 Torr (placebo trial). Oxygen consumption, ventilation, and other exercise variables were similarly unaffected by drug treatment. Although plasma histamine increased with exercise, values did not differ between trials, and urinary leukotriene E4and 11β-prostaglandin F2αlevels were unchanged after exercise. Postexercise sputum revealed no significant changes in markers of inflammation. These results demonstrate that EIAH in young athletes is not attenuated with acute administration of drugs targeting histamine and bioactive lipids. We conclude that airway inflammation is of insufficient magnitude to cause impairments in gas exchange and does not appear to be linked to EIAH in healthy young athletes.

The causes of exercise-induced hypoxemia (EIH) remain unclear. We studied the mechanisms of EIH in highly trained cyclists. Five subjects had no significant change from resting arterial[Formula: see text]([Formula: see text]; 92.1 ± 2.6 Torr) during maximal exercise (C), and seven subjects (E) had a >10-Torr reduction in [Formula: see text] (81.7 ± 4.5 Torr). Later, they were studied at rest and during various exercise intensities by using the multiple inert gas elimination technique in normoxia and hypoxia (13.2% O2). During normoxia at 90% peak O2 consumption,[Formula: see text] was lower in E compared with C (87 ± 4 vs. 97 ± 6 Torr, P < 0.001) and alveolar-to-arterial O2tension difference (a-[Formula: see text]) was greater (33 ± 4 vs. 23 ± 1 Torr, P < 0.001). Diffusion limitation accounted for 23 (E) and 13 Torr (C) of thea-[Formula: see text]( P < 0.01). There were no significant differences between groups in arterial[Formula: see text]([Formula: see text]) or ventilation-perfusion (V˙a/Q˙) inequality as measured by the log SD of the perfusion distribution (logSDQ˙). Stepwise multiple linear regression revealed that lung O2 diffusing capacity ([Formula: see text]), logSDQ˙, and[Formula: see text] each accounted for ∼30% of the variance in [Formula: see text]( r = 0.95, P < 0.001). These data suggest that EIH has a multifactorial etiology related to[Formula: see text],V˙a/Q˙inequality, and ventilation.

Noninvasive measurement of cardiac output (Q˙t) is problematic during heavy exercise. We report a new approach that avoids unpleasant rebreathing and resultant changes in alveolar[Formula: see text] or[Formula: see text] by measuring short-term acetylene (C2H2) uptake by an open-circuit technique, with application of mass balance for the calculation ofQ˙t. The method assumes that alveolar and arterial C2H2pressures are the same, and we account for C2H2recirculation by extrapolating end-tidal C2H2back to breath 1 of the maneuver. We correct for incomplete gas mixing by using He in the inspired mixture. The maneuver involves switching the subject to air containing trace amounts of C2H2and He; ventilation and pressures of He, C2H2, and CO2are measured continuously (the latter by mass spectrometer) for 20–25 breaths. Data from three subjects for whom multiple Fick O2measurements ofQ˙t were available showed that measurement ofQ˙t by the Fick method and by the C2H2technique was statistically similar from rest to 90% of maximal O2consumption (V˙o2 max). Data from 12 active women and 12 elite male athletes at rest and 90% ofV˙o2 maxfell on a single linear relationship, with O2consumption (V˙o2) predictingQ˙t values of 9.13, 15.9, 22.6, and 29.4 l/min atV˙o2of 1, 2, 3, and 4 l/min. Mixed venous [Formula: see text] predicted from C2H2-determinedQ˙t, measuredV˙o2, and arterial O2concentration was ∼20–25 Torr at 90% ofV˙o2 maxduring air breathing and 10–15 Torr during 13% O2breathing. This modification of previous gas uptake methods, to avoid rebreathing, produces reasonable data from rest to heavy exercise in normal subjects.