Search

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.

BAUMANN, J. M., K. W. RUNDELL, T. M. EVANS, and A. M. LEVINE. Effects of Cysteine Donor Supplementation on Exercise-Induced Bronchoconstriction. Med. Sci. Sports Exerc., Vol. 37, No. 9, pp. 1468 –1473, 2005. Purpose: Reactive oxygen/ nitrogen species (ROS/RNS) in resident airway cells may be important in bronchoconstriction following exercise. Glutathione (GSH) is a major lung antioxidant and could influence pathological outcomes in individuals with exercise-induced bronchoconstriction (EIB). This study examined the effects of supplementation with undenatured whey protein (UWP) in subjects exhibiting airway narrowing following eucapnic voluntary hyperventilation (EVH), a surrogate challenge for diagnosis of EIB. UWP is a cysteine donor that augments GSH production. Methods: In a randomized, double-blind, placebo-controlled study, 18 EIB-positive subjects (age: 25.2 9.01 yr; weight: 77.3 18.92 kg; height: 1.7 0.09 m) with post-EVH falls of 10% in FEV1 received 30 g UWP (TX) or casein placebo (PL)/d. Subjects performed 6-min EVH challenges before and after 4 and 8 wk of supplementation. Exhaled nitric oxide (eNO) was measured serially before spirometry and at 1-wk intervals. Spirometry was performed pre- and 5, 10, and 15 min postchallenge Results: Subjects exhibited significant mean improvement in postchallenge falls in FEV1 from 0w k (22.6 12.22%) with TX at 4( 18.9 12.89%, P 0.05) and 8 wk (16.98 11.61%, P 0.05) and significant mean reduction in post-EVH peak falls in FEF25–75 from 0w k (40.6 15.28%) with TX at 4 (33.1 17.11%, P 0.01) and 8 (29.7 17.42%, P 0.05) wk. No changes in FEV1 or FEF25–75 were observed in the PL group at any time point. Mean eNO for PL and TX groups at 0, 4, and 8 wk (46.8 31.33, 46.5 35.73, 49.3 37.12 vs 35.2 26.87, 29.1 17.26, 34.7 21.11 ppb, respectively) was not significantly different. Conclusions: UWP may augment pulmonary antioxidant capacity and be therapeutically beneficial in individuals exhibiting EIB, as postchallenge pulmonary function improved with supplementation. The lack of significant change in eNO suggests that the pulmonary function improvements from UWP supplementation are independent of eNO. Key Words: ASTHMA, INFLAMMATION, PULMONARY FUNCTION, WHEY PROTEIN, GLUTATHIONE.

PURPOSE: Exercise-induced bronchoconstriction (EIB) is high among ice rink athletes and may be related to exercise ventilation of rink air pollutants. Impaired postchallenge expiratory flows are common for this population; however, baseline lung function and symptoms have not been fully evaluated. METHODS: We examined resting lung function and asthma-like symptoms in relation to airway hyperresponsiveness in National Team female ice hockey players (N = 43). Subjects were grouped according to observed symptoms and medical history as symptomatic ('S') or asymptomatic ('A'). Baseline and postexercise lung function was determined. RESULTS: Seventeen (39.5%) presented symptoms and 9 (21%) had EIB. Baseline FEV1, FEV1/FVC, and FEF25-75 were different between 'S' and 'A' (102 +/- 14% vs 116 +/- 12%, 77.7 +/- 7.5 vs 88.2 +/- 4.5, and 74 +/- 22% vs 118 +/- 24%, respectively; P < 0.05); FVC and PEF were not different. Ten 'S' athletes had

In practice, tests of maximal oxygen uptake (.VO2max) are often preceded by a lactate profile, a highly intense but submaximal exercise bout. The .VO2max response to preceding high-intensity submaximal exercise, with or without a rest period, has not been determined. If .VO2max is limited after a lactate profile, exercise-induced hypoxemia (EIH) may explain the deficit. The purposes of this study were to: 1) examine the effects of high-intensity submaximal exercise, with or without rest, on subsequent .VO2max; and 2) evaluate the role of EIH in causing any observed changes.Ten healthy, well-trained, male cross-country skiers (age = 20.5 +/- 4.7 yr, height = 181.6 +/- 6.0 cm, mass = 72.1 +/- 5.7 kg) completed three exercise trials: an incremental run to fatigue (MAX), MAX preceded by a high-intensity submaximal run (lactate profile) and a 20-min rest period (discontinuous protocol [DC]), and MAX preceded by a high-intensity submaximal exercise run with no rest (continuous protocol [C]). .VO2max, minute ventilation, and arterial oxygen saturation were measured throughout, and diffusion capacity was evaluated 2 min postexercise. RESULTS No significant between trial differences were observed, although the difference between .VO2max determined during the MAX trial (62.7 +/- 6.7 mL.kg-1.min-1) and during the DC trial (58.3 +/- 4.4 mL.kg-1.min-1) approached significance (P = 0.059). DC .VO2max responses could be separated into two groups: five responders whose .VO2max suffered during the DC trial (decreased7.5% from MAX) and five nonresponders, whose .VO2max was unaffected by preceding submaximal exercise and a rest period. Responders showed greater aerobic capacity during the MAX trial..VO2max is significantly reduced in approximately 50% of cross-country skiers when a maximal exercise test is preceded by high-intensity submaximal exercise and a 20 min rest period; the role of EIH in causing these reductions is unclear.

HOFFMAN, J. R., J. IM, K. W. RUNDELL, J. KANG, S. NIOKA, B. A. SPEIRING, R. KIME, and B. CHANCE. Effect of Muscle Oxygenation during Resistance Exercise on Anabolic Hormone Response. Med. Sci. Sports Exerc., Vol. 35, No. 11, pp. 1929 –1934, 2003. Purpose: The mechanisms that underlie the affect of acute program variables on muscle growth and strength development for strength/power athletes have been of great interest. This investigation examined the affects of two different resistance exercise protocols on muscle oxygenation, and the anabolic hormonal response to such exercise. Methods: Eleven experienced resistance-trained male athletes performed four sets of the squat exercise using either a low-intensity, high-volume (LI; 15 repetitions at 60% one-repetition maximum [1-RM]) or high-intensity, low-volume (HI; 4 repetitions at 90% 1-RM) load. Venous blood samples were obtained before (Pre), immediate (IP), 20- (20P), and 40-min (40P) postexercise. Continuous-wave near-infrared spectroscopy was used to measure oxygen desaturation during exercise. Results: No differences in muscle deoxygenation were seen between LI and HI. However, time-dependent postexercise reoxygenation was significantly different between the two exercise sessions (35.3 17.4 s vs 24.5 14.3 s in LI and HI, respectively). Testosterone and growth hormone (GH) concentrations were significantly elevated from Pre at IP, 20P, and 40P in both LI and HI. GH concentrations were higher (P 0.05) for LI than at HI at 20P and 40P. Conclusion: Muscle oxygen recovery kinetics appeared to be influenced by differences in the intensity and volume of exercise, and delayed reoxygenation appears to affect the GH response to exercise. Key Words: TESTOSTERONE, GROWTH HORMONE, WEIGHT TRAINING, NEAR-INFRARED SPECTROSCOPY, MUSCLE ISCHEMIA

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.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.Resting FEV1 values were above predicted values (114--121%) and not different between groups. Twenty-six percent of the study population demonstrated10% 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 (P0.05). 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.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.

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.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.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.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.

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.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.For W, HR, VO2, and VE during carriage were higher at all speeds, LA was higher at the fastest speed (P0.05). For M, VO2 and VE were higher at all speeds, HR and LA were higher at 2.68 and 2.91 m.s-1 (P0.05). Rifle mass as percent of body mass was different between W and M (6.6 +/- 0.7% vs 5.0 +/- 0.3%, P0.05). 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).The large range in cost between individuals (0.2 +/- 0.08 and 0.19 +/- 0.17 L.min-1; for WM, respectively) suggests that individual economies for load carriage can be improved.

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 (P0.05). OD was highly related to LA (r0.95) but not to whole body VO2. Blood volume change was less for LS than for US (P0.05). 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.

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.