Dephosphorylation of simian virus 40 large-T antigen and p53 protein by protein phosphatase 2A: inhibition by small-t antigen.

Simian virus 40 (SV40) large-T antigen and the cellular protein p53 were phosphorylated in vivo by growing cells in the presence of 32Pi. The large-T/p53 complex was isolated by immunoprecipitation and used as a substrate for protein phosphatase 2A (PP2A) consisting of the catalytic subunit (C) and the two regulatory subunits, A and B. Three different purified forms of PP2A, including free C, the AC form, and the ABC form, could readily dephosphorylate both proteins. With both large-T and p53, the C subunit was most active, followed by the AC form, which was more active than the ABC form. The activity of all three forms of PP2A toward these proteins was strongly stimulated by manganese ions and to a lesser extent by magnesium ions. The presence of complexed p53 did not affect the dephosphorylation of large-T antigen by PP2A. The dephosphorylation of individual phosphorylation sites of large-T and p53 were determined by two-dimensional peptide mapping. Individual sites within large-T and p53 were dephosphorylated at different rates by all three forms of PP2A. The phosphates at Ser-120 and Ser-123 of large-T, which affect binding to the origin of SV40 DNA, were removed most rapidly. Three of the six major phosphopeptides of p53 were readily dephosphorylated, while the remaining three were relatively resistant to PP2A. Dephosphorylation of most of the sites in large-T and p53 by the AC form was inhibited by SV40 small-t antigen. The inhibition was most apparent for those sites which were preferentially dephosphorylated. Inhibition was specific for the AC form; no effect was observed on the dephosphorylation of either protein by the free C subunit or the ABC form. The inhibitory effect of small-t on dephosphorylation by PP2A could explain its role in transformation.

Control of protein phosphatase 2A by simian virus 40 small-t antigen.

Soluble, monomeric simian virus 40 (SV40) small-t antigen (small-t) was purified from bacteria and assayed for its ability to form complexes with protein phosphatase 2A (PP2A) and to modify its catalytic activity. Different forms of purified PP2A, composed of combinations of regulatory subunits (A and B) with a common catalytic subunit (C), were used. The forms used included free A and C subunits and AC and ABC complexes. Small-t associated with both the free A subunit and the AC form of PP2A, resulting in a shift in mobility during nondenaturing polyacrylamide gel electrophoresis. Small-t did not interact with the free C subunit or the ABC form. These data demonstrate that the primary interaction is between small-t and the A subunit and that the B subunit of PP2A blocks interaction of small-t with the AC form. The effect of small-t on phosphatase activity was determined by using several exogenous substrates, including myosin light chains phosphorylated by myosin light-chain kinase, myelin basic protein phosphorylated by microtubule-associated protein 2 kinase/ERK1, and histone H1 phosphorylated by protein kinase C. With the exception of histone H1, small-t inhibited the dephosphorylation of these substrates by the AC complex. With histone H1, a small stimulation of dephosphorylation by AC was observed. Small-t had no effect on the activities of free C or the ABC complex. A maximum of 50 to 75% inhibition was obtained, with half-maximal inhibition occurring at 10 to 20 nM small-t. The specific activity of the small-t/AC complex was similar to that of the ABC form of PP2A with myosin light chains or histone H1 as the substrate. These results suggested that small-t and the B subunit have similar qualitative and quantitative effects on PP2A enzyme activity. These data show that SV40 small-antigen binds to purified PP2A in vitro, through interaction with the A subunit, and that this interaction inhibits enzyme activity.

The amino-terminal transforming region of simian virus 40 large T and small t antigens functions as a J domain.

Simian virus 40 (SV40) encodes two proteins, large T antigen and small t antigen that contribute to virus-induced tumorigenesis. Both proteins act by targeting key cellular regulatory proteins and altering their function. Known targets of the 708-amino-acid large T antigen include the three members of the retinoblastoma protein family (pRb, p107, and p130), members of the CBP family of transcriptional adapter proteins (cap-binding protein [CBP], p300, and p400), and the tumor suppressor p53. Small t antigen alters the activity of phosphatase pp2A and transactivates the cyclin A promoter. The first 82 amino acids of large T antigen and small t antigen are identical, and genetic experiments suggest that an additional target(s) important for transformation interacts with these sequences. This region contains a motif similar to the J domain, a conserved sequence found in the DnaJ family of molecular chaperones. We show here that mutations within the J domain abrogate the ability of large T antigen to transform mammalian cells. To examine whether a purified 136-amino-acid fragment from the T antigen amino terminus acts as a DnaJ-like chaperone, we investigated whether this fragment stimulates the ATPase activity of two hsc70s and discovered that ATP hydrolysis is stimulated four- to ninefold. In addition, ATPase-defective mutants of full-length T antigen, as well as wild-type small t antigen, stimulated the ATPase activity of hsc70. T antigen derivatives were also able to release an unfolded polypeptide substrate from an hsc70, an activity common to DnaJ chaperones. Because the J domain of T antigen plays essential roles in viral DNA replication, transcriptional control, virion assembly, and tumorigenesis, we conclude that this region may chaperone the rearrangement of multiprotein complexes.

Dietary polyunsaturated fatty acids in asthma- and exercise-induced bronchoconstriction.

Despite progress that has been made in the treatment of asthma, the prevalence and burden of this disease has continued to increase. While pharmacological treatment of asthma is usually highly effective, medications may have significant side effects or exhibit tachyphylaxis. Alternative therapies for treatment that reduce the dose requirements of pharmacological interventions would be beneficial, and could potentially reduce the public health burden of this disease. Ecological and temporal data suggest that dietary factors may have a role in recent increases in the prevalence of asthma. A possible contributing factor to the increased incidence of asthma in Western societies may be the consumption of a proinflammatory diet. In the typical Western diet, 20- to 25-fold more omega (n)-6 polyunsaturated fatty acids (PUFA) than n-3 PUFA are consumed, which promotes the release of proinflammatory arachidonic acid metabolites (leukotrienes and prostanoids). This review will analyze the evidence for the health effects of n-3 PUFA in asthma- and exercise-induced bronchoconstriction (EIB). While clinical data evaluating the effect of omega-3 fatty acid supplementation in asthma has been equivocal, it has recently been shown that fish oil supplementation, rich in n-3 PUFA, reduces airway narrowing, medication use, and proinflammatory mediator generation in nonatopic elite athletes with EIB. These findings are provocative and suggest that dietary fish oil supplementation may be a viable treatment modality and/or adjunct therapy in asthma and EIB.

Effects of montelukast on airway narrowing from eucapnic voluntary hyperventilation and cold air exercise.

BACKGROUND: Exercise induced bronchoconstriction (EIB) is common in elite athletes. Eucapnic voluntary hyperventilation (EVH) is a laboratory test recommended for the identification of EIB in athletes, secondary to a field exercise challenge. Montelukast attenuates EIB, but its protective effect against airway narrowing from EVH has not been investigated. OBJECTIVE: To examine the effectiveness of montelukast after exercise and after EVH. METHODS: A randomised, placebo controlled, double blind, crossover study was performed with 11 physically active EIB positive subjects (eight men, three women; mean (SD) age 22.8 (6.8) years). Six hours before each of the following challenges 10 mg montelukast or placebo was ingested: (a) a six minute, cold air (-3 degrees C) maximal effort work accumulation cycle ergometer exercise; (b) EVH, breathing 5% CO(2) compressed air at 85% maximal voluntary ventilation for six minutes. Spirometry was performed before and 5, 10, and 15 minutes after the challenge. At least 48 hours was observed between challenges. RESULTS: No differences in forced expiratory volume in one second (FEV(1)) were found after the two challenges. Exercise and EVH resulted in falls in FEV(1) of 22.4 (18.0) and 25.6 (16.8) respectively. Falls in FEV(1) after montelukast were less than after placebo (10.6 (10.6) and 14.3 (11.3) after exercise and EVH respectively; p<0.05). Montelukast provided protection against bronchoconstriction (59% and 53%; p<0.05) for eight exercising subjects and 10 EVH subjects; no protection was afforded for three exercising and one EVH challenged subject. CONCLUSIONS: Both exercise and EVH were potent stimuli of airway narrowing. A single dose of montelukast provided reasonable protection in attenuating bronchoconstriction from either exercise or EVH. The similar protection by montelukast suggests that EVH is a suitable laboratory surrogate for EIB evaluation.

Cultured human keratinocytes synthesize and secrete endothelin-1.

The human epidermal-melanin unit exists as a complex interplay of cell-cell interactions. Melanocytes synthesize melanin and transfer it to the surrounding keratinocytes, which, in turn, produce factors that affect melanocyte homeostasis, growth, and melanization. Endothelin-1 (ET-1), a vasoconstrictor peptide produced by endothelial cells, has recently been shown to stimulate human melanocyte proliferation and tyrosinase activity. To investigate the possibility that keratinocytes synthesize and secrete ET-1, we grew human keratinocytes in a defined serum-free medium and measured ET-1 levels in the keratinocytes and the keratinocyte-conditioned medium. Northern analysis of keratinocyte total RNA also was performed. We found that human keratinocytes express preproET-1 mRNA and translate the message to ET-1 protein, which is secreted into the keratinocyte medium. Human keratinocytes produced ET-1 in a time-dependent manner with total production of 20.1 +/- 1.1 pg ET-1/10(6) cells at 24 h (n = 7). Although total ET-1 production (secreted plus cell-associated ET-1) was similar, the proportion of secreted versus cell-associated ET-1 varied widely among the different donors. We have found that human keratinocytes synthesize and secrete ET-1 in vitro. From these data we believe that the keratinocyte could be an in vivo epidermal source of this melanocyte growth and pigmentation factor.

AMP deaminase binding in rat skeletal muscle after high-intensity running.

Skeletal muscle deaminates a substantial fraction of its adenylate pool to inosine 5'-monophosphate (IMP) when the rate of energy expenditure exceeds supply. How AMP deaminase is activated in vivo is unclear because the substrate affinity is quite low (Michaelis constant approximately 1-2 mM) relative to estimated concentrations of free AMP in skeletal muscle (0.2-1 microM). AMP deaminase:myosin binding causes a large increase in substrate affinity; whether this binding occurs during physiological exercise is uncertain. Exhaustive high-speed (60 m/min) treadmill exercise in rats results in an extensive depletion of adenine nucleotide and a stoichiometric accumulation of IMP (1.5-2 mumol/g) in the superficial vastus lateralis muscles (predominantly fast-twitch white). We measured AMP deaminase:myosin binding after intense exercise and found the bound fraction of AMP deaminase to be increased from 9 +/- 1% at rest to 48 +/- 4% at approximately 45 s after exercise. The extent of binding lessened during recovery from exercise, falling to 32 +/- 4% after approximately 75 s and 21 +/- 2% after approximately 105 s. This postexercise dissociation of AMP deaminase from myosin appeared to be a first-order process (approximately 50 s half time). Treadmill running that leads to deamination also results in AMP deaminase:myosin binding. Binding should activate AMP deaminase and thus favor IMP formation at low physiological concentrations of AMP.

Treadmill roller ski test predicts biathlon roller ski race results of elite U.S. biathlon women.

This study evaluated ski-specific laboratory testing and the relationship of test parameters to biathlon race performance. Since the ski skating technique used exclusively during biathlon racing requires a large upper body contribution, treadmill roller ski test parameters may provide relevant information for ski-specific training and ski performance. Seven top U.S. female biathlon skiers performed lactate threshold and VO2 peak tests running (TR) and roller skiing (skating technique, RS) on a motor driven treadmill. In addition, a constant workload (14 km.h(-1), 6% grade) roller ski test to exhaustion at race pace (ET) on a motor driven treadmill, and a short-term double pole power test (DP) were also performed. Results indicate that lactate threshold VO2 and HR were significantly lower during RS than TR, DP power (w.kg(-1)) was related to RS VO2 peak (r = 0.90), but not to TR parameters. ET time to exhaustion was related to gross efficiency during ET (r = -0.86), RS VO2 peak (r = 0.80) and DP HR (% peak HR, r = 0.80). These results suggest that ski-specific laboratory testing provides better insight to ski performance than treadmill run testing.

Compromised oxygen uptake in speed skaters during treadmill in-line skating.

The "sitting" posture of speed skating may result in compromised blood flow to the working muscles, thus limiting oxygen uptake. To examine this metabolic problem, male (N = 7) short track speed skaters performed running (TR), in-line skating upright (US), and in-line skating in the "sitting" position (LS) on a motor driven treadmill on randomized days. Each test consisted of four 4-min stages at 2.24, 2.68, 3.13, and 3.58 m.s-1 (5, 6, 7, and 8 mph) at 5% incline. After a brief rest, athletes performed at 4.03 m.s-1 (9 mph) with elevation increasing 1% each minute to exhaustion. Two on-ice 1000-m time trials (TT) were performed to assess the relationship between performance and laboratory measurements. Peak VO2 was lower during LS (57.2 +/- 2.7, 62.3 +/- 4.0, and 64.3 +/- 1.6; for LS, US, and TR, respectively; P < 0.05). At equivalent speeds, submaximal O2 uptake was lower for LS and blood lactate was higher (P < 0.05). LS peak VO2 (ml.kg-1.min-1) was strongly related to TT (P < 0.05). The depressed VO2 and higher blood lactate during LS may be related to decreased knee or trunk angle. Peak VO2 values during skating did not approach values during running. Evaluation of speed skaters in a sports-specific test is congruent with performance and demonstrates potential in addressing the unique physiological demands of the sport.

Effects of drafting during short-track speed skating.

Short-track speed skating involves pack-style racing where five to seven skaters may be on the ice at once. Since average speed for a 3000-m event may exceed 35 km.h-1, drafting may be beneficial. However, the short (111 m) oval track could limit effective drafting space, and high forces required in cornering may compromise potential benefits. We evaluated heart rate (HR)-lactate (LA) responses and post-drafting 3-lap sprint performance using 18 National Team and developmental skaters. Two 4-min trials, one drafting and one leading at 8.8 m.s-1, were performed. In addition, six skaters performed three 3-lap sprints, rested, immediately after a 4-min drafting trial at 9.2 m.s-1, and immediately after an unaided 4-min trial at 9.2 m.s-1. Results demonstrated lower HR and LA responses during drafting (174.0 +/- 9.0 and 5.56 +/- 2.18 vs 180.4 +/- 8.7 and 7.75, P < 0.05) at 8.8 m.s-1. After 4-min trials at 9.2 m.s-1, HR deltas were 6 bpm, lactate values were 9.00 +/- 1.84 and 5.22 +/- 1.18 for unaided and drafting, respectively. Sprint performance was better following drafting (33.46 +/- 1.19 vs 34.03 s, P < 0.05). HR and LA deltas during the 8.8 m.s-1 trials ranged from 0.8 to 12.4 and -0.18 to 5.37, respectively, indicating that some skaters were more effective drafters than others. These results suggest that drafting could be an important strategy in short-track speed skating, and drafting technique should be emphasized in training.

Effect of kinematic variables on performance in women during a cross-country ski race.

The purpose of this study was to investigate the relationship of uphill cycle velocity, cycle length, and cycle rate in top U.S. female skiers during a multiple lap cross-country ski skating race. Eighteen female cross-country skiers served as subjects at the United States Women's 10-km Freestyle 1995 National Championships. The course consisted of two laps of the same 5-km loop. The selected filming section was an 11-12% uphill grade approximately 400 m long located at the 2.5- and 7.5-km mark. The video sector was approximately 12 m long at the conclusion of the climb. During the climb, the skating technique used by all skiers was the V-1. The results demonstrated that cycle length is positively related to cycle velocity during uphill ski skating and ultimately translates to faster race times by female cross-country ski racers. Lap 2 cycle velocity and cycle length demonstrated the strongest relationship to lap time and total race time. Moreover, cycle rate was not related to cycle velocity or lap race times and was not different between successful and less successful skiers. The slower climbing velocity noted during the latter half of the 10-km race was a consequence of a decreased cycle length and not cycle rate. This suggests that the degree of physical conditioning could be a factor in the ability to maintain cycle length and thus uphill cycle velocity.

Physiological characteristics and performance of top U.S. biathletes.

Success in biathlon involves skiing fast and shooting accurately. The purpose of this study was to determine whether physiological laboratory test results relate to success in biathlon. Tests included treadmill run and double-pole lactate profile and VO2peak tests, and a double-pole peak power test (UBP). 1993 National Points Rank (NR), racing ski time (ST), and shooting percentage (SP) from 1993 World Team Trials and laboratory test results (1993; N = 11 males, 10 females) were examined. Of athletes tested, six males and six females were top 10 U.S. ranked. Significance was identified between NR and ST (males, r = -0.88; females, r = -0.91). NR and SP were related for females (r = 0.75). Maximum run time during the VO2peak test was the only parameter related to NR (r = 0.72) or ST (r = -0.80) for males. Significance was identified for an uphill 1 km on snow double-pole time trial to NR (r = -0.84) and SP (r = -0.79) (subgroup; N = 8 males). For females, NR was related to running VO2peak (r = 0.81) and UBP (r = 0.95). Double-pole and running VO2peak were related to SP for women. This study suggests that SP is more important to NR for females than for males, and gender-specific tests might better predict success in elite biathlon skiers.

Energy cost of rifle carriage in biathlon skiing.

PURPOSE: Since biathlon racing involves cross-country skiing while carrying a minimum weight 3.5-kg rifle, energy cost for rifle carriage could be significant to race outcome. The purposes of this study were to: 1) compare physiological measurements of biathletes roller skiing with and without rifle carriage, 2) compare energy cost of rifle carriage between women and men, 3) examine the relationship of cycle length and cycle rate to energy cost of rifle carriage, and 4) compare physiological measurements to calculated estimates of power requirements of rifle carriage. METHODS: We examined metabolic cost of rifle carriage during inclined roller ski-skating. National Team Biathletes (7 W, 8 M) performed treadmill roller ski-skating (2.46, 2.68, and 2.91 m.s-1, 8% incline, 5-min stages) with and without a 3.65 kg rifle. RESULTS: For W, HR, VO2, and VE during carriage were higher at all speeds, LA was higher at the fastest speed (P < 0.05). For M, VO2 and VE were higher at all speeds, HR and LA were higher at 2.68 and 2.91 m.s-1 (P < 0.05). Rifle mass as percent of body mass was different between W and M (6.6 +/- 0.7% vs 5.0 +/- 0.3%, P < 0.05). Percent increase in VO2 (2.1% and 1.3% per kg load; for W and M, respectively) was not different than rifle mass as percent body wt. Cycle length was related to increased VO2 and LA during rifle carriage for W (r = -0.59 and -0.70 to -0.85), and to LA for M (r = -0.66 to -0.83). CONCLUSION: The large range in cost between individuals (0.2 +/- 0.08 and 0.19 +/- 0.17 L.min-1; for W & M, respectively) suggests that individual economies for load carriage can be improved.

Hemoglobin/myoglobin desaturation during speed skating.

The characteristic low "sitting" position of competitive speed skating has been shown to result in a right shifted heart rate-VO2 curve and elevated submaximal blood lactate values compared with running or cycling. This is thought to be a consequence of reduced blood flow and subsequent oxygen delivery to the exercising muscle while speed skating. Duel wavelength spectrophotometry was used to measure oxygenated and deoxygenated hemoglobin/myoglobin (OD) in the capillary bed of five muscle groups during in-line skating in upright (US) and low (LS) positions. Eight U.S. speed skaters (4 category 1) performed US and LS at 2.68 and 3.13 m.s-1 (4% grade) on a wide (2.44 m) treadmill (4 trials, 5 min each, 20 min recovery between trials). Expired gas parameters and blood lactate (LA) concentrations were determined for each trial. Hip and knee angles were measured (PEAK Motion Analysis) and were significantly different in US and LS. For similar oxygen uptake during US and LS (44.9 +/- 2.79, 45.6 +/- 3.52), heart rate and LA were significantly higher during LS (172 +/- 11 vs 179 +/- 10, 4.35 +/- 2.19 vs 8.70 +/- 3.60). Deoxygenation was significantly greater during LS than during US at both speeds and was greater at 3.13 m.s-1 (P < 0.05). OD was highly related to LA (r > 0.95) but not to whole body VO2. Blood volume change was less for LS than for US (P < 0.05). Increased deoxygenation in the capillary bed of the exercising quadriceps during LS versus US is consistent with the hypothesis that blood flow and subsequent O2 delivery is compromised in the low speed skating position.

Hemoglobin/myoglobin oxygen desaturation during Alpine skiing.

PURPOSE: To investigate muscle blood volume (BV) change and hemoglobin/myoglobin oxygen desaturation (OD) during simulated giant slalom (GS) and slalom (SL) Alpine ski racing. METHODS: Joint angle, BV, OD, and heart rate (HR) were evaluated during GS and SL events in 30 junior elite skiers ages 9--17 yr (13.5 +/- 2.3). Subjects were stratified by ski class and age: group I, J1 and J2, ages 15--18 yr (16.8 +/- 0.8); group II, J3, 13--14 yr (13.6 +/- 0.7); and group III, J4 and J5, 9--12 yr (11.5 +/- 1.2). Near-infrared spectrophotometry (NIRS) was used to measure BV and OD in the capillary bed of the vastus lateralis during trials. Maximal OD was determined during thigh cuff ischemia (CI). Quadriceps cross-sectional area (CSA) was estimated by skin-fold and thigh circumference. RESULTS: Joint angles were smaller (P < 0.05) during GS than SL for ankle (83.8 +/- 11.9 degrees; 98.6 +/- 15.7 degrees ), knee (107.4 +/- 14.9 degrees; 118.3 +/- 18.0 degrees ), and hip (98.8 +/- 14.3 degrees; 107.5 +/- 16.2 degrees ). BV reduction from rest to peak exercise (Delta BV) was 30% greater (P < 0.05) during the GS than SL, whereas Delta OD was 33% greater (P < 0.05) during GS. Delta OD, relative to CI OD, was greater for all subjects during GS (79.2 +/- 3.7%) than SL (65.7 +/- 4.4%). This pattern continued within groups; group II displayed the greatest relative desaturation (82.9 +/- 7.6%). CSA was larger in older skiers (92.5 +/- 21.6; 72.5 +/- 12.3; 65.3 +/- 21.2 cm(2)) and correlated with Delta OD (P < 0.05). CONCLUSION: The larger reduction in BV (Delta BV change) and greater OD when skiers assumed lower posture during GS than SL may be related to greater effective static load secondary to higher percent of maximal voluntary contraction and is consistent with compromised blood flow to working muscle.

Effect of slope variation and skating technique on velocity in cross-country skiing.

The purpose of the present study was to investigate the effect of slope variations upon the maximal velocity attainable by cross-country ski racers using three skating techniques (V-1, V-2, and Gunde). Nine (2 females, 7 males) junior ski racers (16.0 +/- 0.4 yr of age, mean +/- SEM) exhibiting strong technical skills participated in the study. The subjects were required to skate at maximal velocity over five different courses (length 120-200 m) with mean slopes of -1, 0, 6, 9, and 12%. Video analysis was used to determine skiing velocity, cycle length, and cycle rate. Heart rate was monitored to verify intensity of exertion. Results indicated that intensities were similar to those observed while racing. Velocities for the three techniques were not different for -1, 0, and 6% slopes. However V-1 was significantly faster (P < 0.01) at 9% and 12% inclines. Velocity was highly correlated to cycle length (P < 0.01) but unrelated to cycle rate. Cycle length was significantly different between techniques (P < 0.01) and varied across slopes. Cycle rate was significantly different between techniques (P < 0.01) but did not vary across slopes. Thus, our results indicate that any of the three techniques is adequate on flat and rolling terrain, but V-1 should be used at slopes of 9% and above. It is also concluded that during short trials skied at maximal velocity, skiing velocity is highly dependent on cycle length and independent of cycle rate.

Kinematics of cross-country ski racing.

This study investigated the evolution of skiing velocity, cycle length, and cycle rate in elite and subelite skiers during cross-country ski races. Senior male cross-country skiers engaged respectively in a 30-km skating race (N = 34) or a 50-km classical race (N = 27) were videotaped as they skied two different sections of 30 m, a 7 degrees uphill, and a flat section. In the skating race, most skiers used the offset technique on uphill and the 2-skate on flat, while the preferred techniques during the classical race were the diagonal stride for uphill and double-poling on flat. Results demonstrated that faster skiers had longer cycle lengths than slower skiers except for the flat sections of the classical race. Cycle rate was not different between skiers of different performance levels in any circumstances or races. Decreased velocity observed during the second half of the skating race was almost entirely due to a decrease in cycle length. We conclude that slower athletes should emphasize extending cycle length during their technical training. Therefore, skiers should place an emphasis on strength and power training to increase their kick and pole pushes and enhance cycle length.

Exercise-induced asthma screening of elite athletes: field versus laboratory exercise challenge.

PURPOSE: The purpose of this study was to compare a laboratory based exercise challenge (LBC) to a field based exercise challenge (FBC) for pulmonary function test (PFT) exercise-induced asthma (EIA) screening of elite athletes. METHODS: Twenty-three elite cold weather athletes (14 men, 9 women) PFT positive for EIA (FBC screened) served as subjects. Twenty-three gender and sport matched controls (nonasthmatics) were randomly selected to establish PFT reference values for normal elite athletes. Before FBC, athletes completed a medical history questionnaire for EIA symptoms. FBC evaluations consisted of baseline spirometry, actual or simulated competition, and 5, 10, and 15 min postexercise spirometry. PFT positive athletes were evaluated in the laboratory using an exercise challenge simulating race intensity (ambient conditions: 21 degrees C, 60% relative humidity). PFT procedures were identical to FBC. RESULTS: 91% of PFT positive and 48% of PFT normal athletes reported at least one symptom of EIA, with postrace cough most frequent. Baseline spirometry was the same for PFT positives and normal controls. Lower limit reference range (MN - 2 SD) of FEV1 for controls suggests that postexercise decrements of greater than approximately -7% indicate abnormal airway response in this population. Exercise time duration did not effect bronchial reactivity; 78% of FBC PFT positives were PFT normal post-LBC. CONCLUSION: Self-reported symptoms by elite athletes are not reliable in identifying EIA. Reference range criterion for FEV1 decrement in the elite athlete postexercise contrasts current recommended guidelines. Moreover, a large number of false negatives may occur in this population if EIA screening is performed with inadequate exercise and environmental stress.

Incidence of exercise-induced bronchospasm in Olympic winter sport athletes.

PURPOSE: The purpose of this project was to determine the incidence of exercise-induced bronchospasm (EIB) among U.S. Olympic winter sport athletes. METHODS: Subjects included female and male members of the 1998 U.S. Winter Olympic Team from the following sports: biathlon, cross-country ski, figure skating, ice hockey, Nordic combined, long-track speedskating, and short-track speedskating. Assessment of EIB was conducted in conjunction with an "actual competition" (Olympic Trials, World Team Trials, World Cup Event, U.S. National Championships) or a "simulated competition" (time trial, game), which served as the exercise challenge. Standard spirometry tests were performed preexercise and at 5, 10, and 15 min postexercise. An athlete was considered EIB-positive based on a postexercise decrement in FEV1 > or = 10%. RESULTS: For the seven sports evaluated on the 1998 U.S. Winter Olympic Team, the overall incidence of EIB across all sports and genders was 23%. The highest incidence of EIB was found in cross-country skiers, where 50% of the athletes (female = 57%; male = 43%) were diagnosed with EIB. Across the seven sports evaluated, the prevalence of EIB among the female and male athletes was 26% and 18%, respectively. Among those individuals found to be EIB-positive were athletes who won a team gold medal, one individual silver medal, and one individual bronze medal at the Nagano Winter Olympics. CONCLUSIONS: These data suggest that: 1) EIB is prevalent in several Olympic winter sports and affects nearly one of every four elite winter sport athletes; 2) the winter sport with the highest incidence of EIB is cross-country skiing; 3) in general, EIB is more prevalent in female versus male elite winter sport athletes; and 4) athletes may compete successfully at the international level despite having EIB.

Self-reported symptoms and exercise-induced asthma in the elite athlete.

PURPOSE: The purpose of this study was to compare self-reported symptoms for exercise-induced asthma (EIA) to postexercise challenge pulmonary function test results in elite athletes. METHODS: Elite athletes (N = 158; 83 men and 75 women; age: 22 +/- 4.4 yr) performed pre- and post-exercise spirometry and were grouped according to postexercise pulmonary function decrements (PFT-positive, PFT-borderline, and PFT-normal for EIA). Before the sport/environment specific exercise challenge, subjects completed an EIA symptoms-specific questionnaire. RESULTS: Resting FEV1 values were above predicted values (114--121%) and not different between groups. Twenty-six percent of the study population demonstrated >10% postexercise drop in FEV1 and 29% reported two or more symptoms. However, the proportion of PFT-positive and PFT-normal athletes reporting two or more symptoms was not different (39% vs. 41%). Postrace cough was the most reported symptom, reported significantly more frequently for PFT-positive athletes (P < 0.05). Sensitivity/specificity analysis demonstrated a lack of effectiveness of self-reported symptoms to identify PFT-positive or exclude PFT-normal athletes. Postexercise lower limit reference ranges (MN-2SDs) were determined from normal athletes for FEV1, FEF25--75% and PEF to be -7%, -12.5%, and -18%, respectively. CONCLUSION: Although questionnaires provide reasonable estimates of EIA prevalence among elite cold-weather athletes, the use of self-reported symptoms for EIA diagnosis in this population will likely yield high frequencies of both false positive and false negative results. Diagnosis should include spirometry using an exercise/environment specific challenge in combination with the athlete's history of asthma symptoms.