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Snyder AC, Kuipers H, Cheng B, Servais R, Fransen E. Overtraining following intensified training with normal muscle glycogen. Med Sci Sports Exerc 1995; 27:1063-70. [PMID: 7564974 DOI: 10.1249/00005768-199507000-00016] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The purpose of this study was to determine if consumption of appropriate amounts of carbohydrate during a period of increased exercise training would protect the athletes from becoming overtrained. Eight male competitive cyclists were monitored and tested during three training periods: a) normal training (moderate intensity, long duration, 7 d, NORM); b) overtraining (high intensity training, 15 d, OVER); and c) recovery (minimal training, 6 d, REC). Throughout the training 160 g of liquid carbohydrate were consumed within the first 2 h after the daily exercise bout. Mean dietary intake (NORM = 13.7 +/- 1.6, OVER = 14.1 +/- 1.0 MJ.d-1) and carbohydrate percent (NORM = 64.0 +/- 2.1, OVER = 67.4 +/- 2.5%) were not different during the different training periods. Similarly, resting muscle glycogen levels were not different (NORM = 530.9 +/- 42.5, OVER = 571.2 +/- 27.5 mumol.g-1 dry weight). Five criteria were used to determine if overtraining occurred in a subject (decreased maximal workload, maximal heart rate, ratio of maximal lactate to rating of perceived exertion (HLa:RPE), and resting plasma cortisol levels, increased affirmative response to a daily questionnaire). All subjects met at least three of the five criteria and thus were classified as overtrained. Therefore, short-term overtraining may occur even when resting muscle glycogen levels are maintained.
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Foster C, Crowe MP, Holum D, Sandvig S, Schrager M, Snyder AC, Zajakowski S. The bloodless lactate profile. Med Sci Sports Exerc 1995; 27:927-33. [PMID: 7658957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The blood lactate profile (HLa-P) is an accepted method of evaluating athletes and providing a basis for the prescription of training intensity. For both logistic and public health reasons HLa-P is less than optimal. In this study we evaluate the relative velocity or the %HR-max, obtained during a training session, as alternatives to HLa-P. Competitive speed skaters (N = 20) performed HLa-P consisting of 5.2000 m/400 m at incremental velocities ranging from very slow to maximal (time = 3.0-5.0 min). Blood lactate measured during a 60-s interval following each repetition was used to construct HLa-P and to predict the velocity associated with steady state (HLa = 4.0-6.5 mmol.l-1). Relative velocity was calculated relative to the velocity of the maximal trial. A plot of relative velocity and %HRmax vs HLa demonstrated that HLa = 4.0-6.5 mmol.l-1 occurred at a relative velocity of 78-88% (R2 = 0.807) and at 84-92 %HRmax (R2 = 0.748). In a separate training session the relative velocity and %HRmax models were cross validated by having the subjects skate 9.2000 m/400 m at constant velocity. HLa changes during the training session defined the presence/absence of steady state (delta HLa < 1.0 mM from trial 3 to 9). Comparing the velocity during the training session vs the velocity predicted from HLa-P, relative velocity model and %HRmax model allowed a test of the accuracy of bloodless means of defining steady state. HLa-P correctly predicted 81% of training session HLa responses, the relative velocity model correctly predicted 78%, and the %HRmax model correctly predicted 68%.(ABSTRACT TRUNCATED AT 250 WORDS)
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Kerk JK, Clifford PS, Snyder AC, Prieto TE, O'Hagan KP, Schot PK, Myklebust JB, Myklebust BM. Effect of an abdominal binder during wheelchair exercise. Med Sci Sports Exerc 1995; 27:913-9. [PMID: 7658955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The purpose of this study was to determine whether use of an abdominal binder would affect oxygen uptake, trunk range of motion, and duration of the stroke phase during wheelchair propulsion. The subjects were six paraplegic wheelchair athletes with T1-T6 injuries and no abdominal muscle function. Each subject performed two trials, one while wearing the binder and one without the binder. Each trial consisted of submaximal and maximal exercise tests conducted on wheelchair rollers. Oxygen uptake was determined by open circuit spirometry while heart rate was determined by telemetry. Max VO2 values averaged 2.51 l.min-1 while average maximum heart rate values were 190 b.min-1. A 3-D video-based motion analysis system was used to obtain kinematic parameters of wheelchair propulsion. In general, 30% of the cycle time was comprised of the stroke phase, while 70% was comprised of the recovery phase across speeds. There were no statistically significant effects of the abdominal binder on any of the cardiovascular or kinematic variables at submaximal or maximal levels of exercise. Under the conditions of this laboratory investigation, it appears that an abdominal binder does not alter physiological or selected biomechanical measures in highly trained athletes.
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Casey MJ, Foster C, Jones EC, Snyder AC, Thompson NN. ASSOCIATION OF LATE MENARCHEAL AGE AND MENSTRUAL DYSFUNCTIONS IN ELITE SPEED SKATERS. Med Sci Sports Exerc 1995. [DOI: 10.1249/00005768-199505001-01294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Foster C, Hector LL, Welsh R, Schrager M, Green MA, Snyder AC. Effects of specific versus cross-training on running performance. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1995; 70:367-72. [PMID: 7649149 DOI: 10.1007/bf00865035] [Citation(s) in RCA: 189] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The cross-training (XT) hypothesis suggests that despite the principle of specificity of training, athletes may improve performance in one mode of exercise by training using another mode. To test this hypothesis we studied 30 well-trained individuals (10 men, 20 women) in a randomized longitudinal trail. Subjects were evaluated before and after 8 weeks of enhanced training (+10%/week), accomplished by adding either running (R) or swimming (XT) to baseline running, versus continued baseline running (C). Both R (-26.4s) and XT (-13.2s) improved time trial (3.2 km) performance, whereas C did not (-5.4s). There were no significant changes during treadmill running in maximum oxygen uptake (VO2peak; -0.2, -6.0, and +2.7%), steady state submaximal VO2 at 2.68 m.s-1 (-1.2, -3.3 and +0.2 ml.kg-1.min-1), velocity at VO2peak (+0.05, +0.25 and +0.09 m.s-1) or accumulated O2 deficit (+11.2, -6.1 and +9.4%) in the R, XT or C groups, respectively. There was a significant increase in velocity associated with a blood lactate concentration of 4 mmol.l-1 in R but not in XT or C (+0.32, +0.07 and +0.08 m.s-1). There were significant changes in arm crank VO2peak (+5%) and arm crank VO2 at 4 mmol.l-1 (+6.4%) in XT. There was no significant changes in arm crank VO2peak (+1.3 and -7.7%) or arm crank VO2 at 4 mmol.l-1 (+0.8 and +0.4%) in R or C, respectively. The data suggest that muscularly non-similar XT may contribute to improved running performance but not to the same degree as increased specific training.
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Snyder AC, Woulfe T, Welsh R, Foster C. A simplified approach to estimating the maximal lactate steady state. Int J Sports Med 1994; 15:27-31. [PMID: 8163322 DOI: 10.1055/s-2007-1021015] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The exercise intensity associated with an elevated but stable blood lactate (HLa) concentration during constant load work (the maximal steady state, MSS) has received attention as a candidate for the "optimal" exercise intensity for endurance training. Identification of MSS ordinarily demands direct measurement of HLa or respiratory metabolism. The purpose of this study was to test the ability of heart rate (HR) to identify MSS during steady state exercise, similar to that used in conventional exercise prescription. Trained runners (n = 9) and cyclists (n = 12) performed incremental and steady state exercise. MSS was defined as the highest intensity in which blood lactate concentration increased < 1.0 mM from minutes 10 to 30. The next higher intensity workbout completed was defined as > MSS. HR models related to the presence or absence of steady state conditions were developed from the upper 95% confidence interval of MSS and the lower 95% confidence interval of > MSS. Cross validation of the model to predict MSS was performed using 21 running and 45 cycling exercise bouts in a separate group. Using the MSS upper 95% confidence interval model 84% and 76% of workbouts were correctly predicted in cyclists and runners, respectively. Using the > MSS lower 95% confidence interval model, 76% and 81% of workbouts were correctly predicted in cyclists and runners, respectively. Prediction errors tended to incorrectly predict non-steady state conditions when steady state had occurred (16/26) (62%). We conclude that use of these simple HR models may predict MSS with sufficient accuracy to be useful when direct HLa measurement is not available.
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Snyder AC. Competency to refuse lifesaving treatment: valuing the nonlogical aspects of a person's decisions. ISSUES IN LAW & MEDICINE 1994; 10:299-320. [PMID: 7829306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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Foster C, Cohen J, Donovan K, Gastrau P, Killian PJ, Schrager M, Snyder AC. Fixed time versus fixed distance protocols for the blood lactate profile in athletes. Int J Sports Med 1993; 14:264-8. [PMID: 8365834 DOI: 10.1055/s-2007-1021175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Laboratory studies of blood lactate accumulation often use a fixed time protocol to define the onset (4 mM) of blood lactate accumulation (OBLA) or other indices of blood lactate concentration. For practical reasons, field studies with athletes often use a fixed distance protocol to accomplish the same goal. Whether these variations of protocol are comparable has not been established. We studied 10 subjects in the laboratory during fixed time (4 minute) and fixed distance (2 km) exercise protocols on a racing bicycle attached to a wind load simulator. The fixed distance studies required 3-6 minutes to complete. We also studied the subjects during fixed distance (2 km) rides in the field. In the laboratory there were no systematic differences in the velocity (34.3 4.6 vs 34.2 +/- 4.6 km.hr-1), VO2 (2.78 +/- 0.60 vs 2.84 +/- 0.62 liters.min-1), or heart rate (159 +/- 16 vs 155 +/- 14 beats.min-1) at OBLA in the fixed time vs fixed distance protocols. The correlation coefficients for velocity (r = 0.97), VO2 (r = 0.97) and heart rate (r = 0.94) further indicate the similarity of results. In the field study there was a significant difference in velocity (29.9 +/- 4.8 vs 34.2 +/- 4.6 km.hr-1) but not heart rate (155 +/- 18 vs 155 +/- 15 beats.min-1) at OBLA versus the fixed distance laboratory study. The correlations for velocity (r = 0.47) and heart rate (r = 0.93) support these data. The results suggest that the practical modification of the lactate profile technique of using fixed distance versus fixed time exercise stages does not systematically influence the outcome, at least for exercise stage durations approximating 4 minutes.
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Foster C, Green MA, Snyder AC, Thompson NN. Physiological responses during simulated competition. Med Sci Sports Exerc 1993; 25:877-82. [PMID: 8350712 DOI: 10.1249/00005768-199307000-00018] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Laboratory studies with competitive athletes often use graded exercise protocols to elicit physiologic responses. This pattern of power output is different than ordinarily employed by athletes during competition. To understand the physiologic responses during competition, we studied 24 athletes (speed skaters, cyclists, triathletes) during simulated competition, a 5-km time trial on a racing bicycle attached to a windload simulator, and during cycle ergometer graded exercise testing (N = 8). During the time trial the velocity pattern was similar to real world competitions, and the subjects indicated that the time trial was perceptually similar to competition. Physiologic responses were of significantly greater magnitude vs graded exercise (VO2max: 3.46 +/- 0.73 vs 3.27 +/- 0.79 l.min-1; VEmax: 138 +/- 27 vs 119 +/- 22 l.min-1; HRmax 184 +/- 11 vs 175 +/- 11 beats x min-1; HLa 14.8 +/- 3.7 vs 11.9 +/- 2.1 mM). All physiologic measures increased steadily throughout the time trial (km 0, 1, 2, 3, 4, and 5: VO2 = 1.03, 2.95, 3.42, 3.69, 3.82, and 3.92 l.min-1; HR = 93, 175, 181, 185, 189, and 194 beats.min-1; VE = 31, 99, 120, 129, 145, and 156 l.min-1; HLa = 2.9, 5.6, 7.2, 9.2, 10.6, and 13.5 mM). In six subjects (speed skaters), the peak values observed during time trial for HR (188 +/- 6 vs 191 +/- 5 beats.min-1) and HLa (16.4 +/- 3.1 vs 17.0 +/- 4.2 mM) were not significantly different than observed during real world competition.(ABSTRACT TRUNCATED AT 250 WORDS)
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Snyder AC, Moorhead K, Luedtke J, Small M. Carbohydrate consumption prior to repeated bouts of high-intensity exercise. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1993; 66:141-5. [PMID: 8472696 DOI: 10.1007/bf01427055] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Rapid depletion of muscle glycogen occurs during activities greater than 100% of maximal oxygen uptake. While carbohydrate ingestion prior to an endurance event has been shown to be beneficial, the effects of carbohydrate ingestion on repeated bouts of high-intensity exercise are not known. Therefore, the purpose of this study was to determine if carbohydrate ingestion prior to repeated bouts of high-intensity, short-duration exercise would improve performance. Ten well-trained male cyclists performed two experimental rides, one 15 min after consumption of 5.0 ml.kg-1 body weight of a 19.7% carbohydrate drink and one following a placebo. The experimental ride consisted of four 1.6 km timed performance rides separated by 4.8 km steady-state rides at 80% of maximal oxygen uptake (between the last two performance rides the steady-state rides were 1.6 km at 80% and 1.6 km at 90%). Blood glucose levels were significantly increased following both the ingestion of the carbohydrate beverage and the performance of the exercise bout. Total exercise time following ingestion of the experimental drink [mean (SD); 25.6 (3.3) min] was not different from that following ingestion of the placebo [25.2 (3.3) min]. Similarly, the sum of all four timed performance rides following ingestion of the experimental drink [6.8 (0.9) min] was not different from that following ingestion of the placebo [6.6 (0.9) min]. In the present study, carbohydrate ingestion 15 min prior to exercise increased blood glucose levels, although performance time was not affected.
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Foster C, Snyder AC, Thompson NN, Green MA, Foley M, Schrager M. Effect of pacing strategy on cycle time trial performance. Med Sci Sports Exerc 1993; 25:383-8. [PMID: 8455455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Despite interest in competitive strategy by coaches and athletes, there are no systematically collected data regarding the effect of differences in pacing strategy on the outcome of middle distance (2-4 min duration) events. In this study different pacing strategies were evaluated using a 2-km time trial on a bicycle attached to a wind load simulator. Well-trained subjects (N = 9) performed five separate time trials with the pace during the first 50% of the trial experimentally constrained within the usual real world range from very slow (approximately 55% of best time) to very fast (approximately 48% of best time). Serial VO2 was measured to estimate the oxidative contributions to the trial and accumulated O2 deficit and postexercise blood lactate measured to estimate the anaerobic contribution to the trial. The evenly paced trial (first 1 km = 50.9% final time) produced the fastest total time. The starting pace to final time relationship was described by a U shaped second order polynomial curve with the nadir for final time at a starting pace of 51% of best total time. There were no systematic differences in serial VO2, accumulated O2 deficit, or postexercise lactate that could account for the pacing related variations in performance. The data support the concept of relatively even pacing in middle distance events with negative consequences for even small variations in this strategy.
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Snyder AC, O'Hagan KP, Clifford PS, Hoffman MD, Foster C. Exercise responses to in-line skating: comparisons to running and cycling. Int J Sports Med 1993; 14:38-42. [PMID: 8440544 DOI: 10.1055/s-2007-1021143] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A comparison of the physiological responses to in-line skating with the more traditional modes of exercise training has not been reported. The purpose of this study was to examine the physiological responses to in-line skating compared with running and cycling. Nine trained volunteers (2 male, 7 female) performed 3-6 submaximal (30-90% VO2max) workloads with each exercise mode. Oxygen uptake, heart rate and blood lactate were measured during each trial. Across the spectrum of oxygen uptakes studied, heart rate was higher with in-line skating than with cycling or running. At a lactate concentration of 4 mM, oxygen uptake was less for in-line skating and cycling than for running. Therefore, while in-line skating may be an effective mode of aerobic exercise, the training adaptations for in-line skating at 4 mM lactate may not be as great as for running, and at a given HR may be less than for running and cycling.
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Snyder AC, Jeukendrup AE, Hesselink MK, Kuipers H, Foster C. A physiological/psychological indicator of over-reaching during intensive training. Int J Sports Med 1993; 14:29-32. [PMID: 8440542 DOI: 10.1055/s-2007-1021141] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Many indicators of over-reaching and over-training have been proposed, using both physiological and psychological techniques. Field testing of athletes has led us to believe that a decrease in the ratio of blood lactate concentration to ratings of perceived exertion indicates a fatigued and/or over-reached state following intensive training. The purpose of this study, therefore, was to test the hypothesis that a decrease in the ratio of blood lactate concentration to ratings of perceived exertion would indicate an over-reached state. Seven well-trained male cyclists performed two weeks each of: normal (moderate) training, overtraining and recovery. During each time period an incremental exercise test was performed to maximal effort with blood lactate concentration (HLa) and ratings of perceived exertion (RPE) obtained for each workload. All seven subjects became over-reached during the two week period of intensive interval training. The ratio of HLa:RPE (multiplied by 100) decreased with all workloads following both one (mean decrease 29.1 +/- 3.0%) and two (mean decrease 48.7 +/- 2.5%) weeks of overtraining. However, only the decrease at the maximal workload was statistically significant. Examining the individual data revealed that at maximal workload all seven subjects had HLa:RPE ratios of less than 100 when over-reached. The ease and speed at which the HLa:RPE ratio can be determined may make it useful for coaches and athletes in monitoring intensive exercise training and recovery.
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Piering AW, Janowski AP, Wehrenberg WB, Moore MT, Snyder AC. Electromyographic analysis of four popular abdominal exercises. J Athl Train 1993; 28:120-6. [PMID: 16558218 PMCID: PMC1317695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
This study was designed to evaluate the effects of four specific sit-up exercises on muscular activity of the rectus abdominis. Pairs of surface electrodes were placed unilaterally on four quadrants of the rectus abdominis, delimited by tendinous inscriptions, in four male subjects. Electromyographic (EMG) recordings were taken while the subjects performed four different abdominal exercises. Each abdominal exercise was hypothesized to have a specific effect on one of the four quadrants of the rectus abdominis. The four exercises analyzed were: 1) long lying crunch, 2) bent knee crunch, 3) leg raise, and 4) vertical leg crunch. Analysis of the standardized EMG recordings demonstrated no significant differences in the mean muscle activity between the four different quadrants, in the mean muscle activity between the four different exercises, and in interactions between the exercises and the quadrants of the rectus abdominis. We conclude that none of the four abdominal exercises studied are specific for strengthening individual muscle quadrants of the rectus abdominis.
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Cheng B, Kuipers H, Snyder AC, Keizer HA, Jeukendrup A, Hesselink M. A new approach for the determination of ventilatory and lactate thresholds. Int J Sports Med 1992; 13:518-22. [PMID: 1459746 DOI: 10.1055/s-2007-1021309] [Citation(s) in RCA: 205] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
In order to determine the ventilatory threshold (VT) and the lactate threshold (LT) in a reliable way, a new method is proposed and compared with conventional methods. The new method consists of calculating the point that yields the maximal distance from a curve representing ventilatory and metabolic variables as a function of oxygen uptake (VO2) to the line formed by the two end points of the curve (Dmax method). Male cyclists (n = 8) performed two incremental exercise tests a week apart. Ventilatory/metabolic variables were measured and blood was sampled for later lactate measurement during each workload and immediately after exercise. No statistical differences were observed in the threshold values (expressed as absolute oxygen uptake; VO2) determined by the Dmax method and the conventional linear regression method (according to O2 equivalent; EqO2) and venous blood at the onset of blood lactate (OBLA), while VT assessed with the conventional linear method (according to the slope of CO2 output; Vslope) yielded significantly lower threshold values. Similar results were obtained from the reproducibility test. Thus, the Dmax method appears to be an objective and reliable method for threshold determination, which can be applied to various ventilatory or metabolic variables yet yield similar results. The results also showed that breathing frequency can be used to determine VT.
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Jeukendrup AE, Hesselink MK, Snyder AC, Kuipers H, Keizer HA. Physiological changes in male competitive cyclists after two weeks of intensified training. Int J Sports Med 1992; 13:534-41. [PMID: 1459749 DOI: 10.1055/s-2007-1021312] [Citation(s) in RCA: 108] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
To study the physiological response to heavy training, seven male competitive cyclists intensified their normal training program for two weeks (IIT) in order to achieve a state of short-term overtraining. The subjects underwent a graded cycle ergometer test to exhaustion, an outdoor 8.5 km time trial and a computerized test to study reaction time and visual perception, before, during and after the two weeks of intensified training and after two weeks of recovery. Furthermore subjects kept a daily log in the form of a questionnaire. After two weeks of IIT all subjects showed symptoms of overtraining: the general state of well being declined as indicated by the questionnaire while performances on time trial (mean +/- SEM: 830 +/- 14 sec-871 +/- 19 sec), contests and maximal power output (mean +/- SEM: 336 7 watt-310 +/- 5 watt) declined significantly. Maximal (mean +/- SEM 11.8 +/- 1.1 mmol.l-1-5.9 +/- 0.5 mmol.l-1) and submaximal lactate values were significantly lowered during ergometer test after the IIT, while the workload at the 4 mmol point increased significantly (mean +/- SEM 234 +/- 10 watt-267 +/- 13 watt). Sleeping heart rate increased significantly (mean +/- SEM 49.5 +/- 9.3 BPM-54.3 +/- 8.8 BPM). Maximal heart rate (mean +/- SEM 185 +/- 3 BPM-178 +/- 2 BPM, mean heart rate during the time trial (mean +/- SEM 178 +/- 2 BPM-169 +/- 2 BPM) and VO2max (mean +/- SEM 4801 +/- 121 ml.min-1-4409 +/- 101 ml.min-1) were all significantly lowered by the IIT.(ABSTRACT TRUNCATED AT 250 WORDS)
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Seifert JG, Snyder AC, Welsh R, Dennis K. The Effects of a 17 Day Road Race Series on Indices of Overtraining. Med Sci Sports Exerc 1992. [DOI: 10.1249/00005768-199205001-00568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ndon JA, Snyder AC, Foster C, Wehrenberg WB. Effects of chronic intense exercise training on the leukocyte response to acute exercise. Int J Sports Med 1992; 13:176-82. [PMID: 1555910 DOI: 10.1055/s-2007-1021252] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Circulatory leukocytes vary significantly in response to acute bouts of exercise. However, little is known concerning the adaptability of this response to chronic intense exercise training. We investigated the circulating leukocytic response to acute exercise in trained athletes during a 28-day intense exercise training program. On day 0, 14, 28 and two days after cessation of the increased training, eight trained male athletes (VO2max greater than 60 ml.kg-1.min-1) were subjected to a 20-km bicycle ergometer time trial. Blood samples were drawn before (PRE, for resting baseline values) and five minutes after (POST, response to acute exercise) the time trial. Beginning on day 0, athletes were instructed to increase the duration of their training 50%. The intense exercise training, which lasted 28 days, was verified weekly. Acute bouts of exercise caused a significant increase (p less than 0.05) in circulating white blood cells, lymphocytes, polymorphonuclear neutrophils and monocytes. The baseline resting values and the magnitude of the response to the acute bouts of exercise in the above parameters were not different during the 28 days of chronic intense exercise training or 2 days after cessation of training as compared to the values observed on day 0. Similarly there was a significant increase (p less than 0.05) in cortisol levels in response to the acute bouts of exercise during the chronic intense exercise training, but the increases were not different from that observed under baseline conditions. These results lead to the conclusion that chronic intense exercise training does not alter the circulating leukocytic response to acute exercise.
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Lamb DR, Snyder AC, Baur TS. Muscle glycogen loading with a liquid carbohydrate supplement. INTERNATIONAL JOURNAL OF SPORT NUTRITION 1991; 1:52-60. [PMID: 1844402 DOI: 10.1123/ijsn.1.1.52] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
This study compared two high carbohydrate (CHO) diets in 14 male runners for effects on muscle glycogen deposition, endurance, and sensations of gastrointestinal discomfort. Muscle glycogen was measured in the vastus lateralis at rest and run time to exhaustion at 75% VO2max was measured following 3-1/2 days on a 50% CHO diet. After 14 days the subjects consumed a 20% CHO diet and continued training to reduce glycogen. During the next 3-1/2 days, subjects ran less and consumed a 90% CHO diet emphasizing pasta and rice (Pasta, n = 7) or lesser amounts of pasta and rice supplemented by a maltodextrin beverage (Supplement, n = 7). Glycogen was again measured, followed by a second run to exhaustion. Compared to the 50% CHO diet, Pasta increased muscle glycogen by 27.1 +/- 12.2 mmoles/kg muscle (M +/- SE; P < 0.05) and run time by 15.7 +/- 5.9 min; Supplement increased glycogen by 43.2 +/- 13.5 mmoles/kg (P < 0.05) and run time by 29.0 +/- 7.4 min (P < 0.05). Total glycogen concentrations and run times were not significantly different for Pasta versus Supplement. Subjects reported less gastrointestinal discomfort and greater overall preference for Supplement than for Pasta. Thus, glycogen loading can be accomplished at least as effectively and more comfortably by substituting a maltodextrin drink for some of the pasta and rice in a glycogen loading diet.
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Snyder AC, Schulz LO, Foster C. Voluntary consumption of a carbohydrate supplement by elite speed skaters. JOURNAL OF THE AMERICAN DIETETIC ASSOCIATION 1989; 89:1125-7. [PMID: 2760372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Kaiserauer S, Snyder AC, Sleeper M, Zierath J. Nutritional, physiological, and menstrual status of distance runners. Med Sci Sports Exerc 1989; 21:120-5. [PMID: 2709975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Amenorrheic runners (AR; N = 8), regularly menstruating runners (RMR; N = 9), and regularly menstruating sedentary controls (RMSC; N = 7) were compared for plasma progesterone levels, plasma lipid levels, menstrual cycle characteristics, physical characteristics, and nutritional adequacy to determine whether exercise training was the major factor associated with menstrual cycle disturbances. Plasma progesterone levels were significantly lower in the AR group subjects than those found during either the follicular or luteal phases of the menstrual cycle for either the RMR or the RMSC subjects. The RMR subjects had a shorter luteal phase length relative to their cycle length than did the RMSC subjects. The AR subjects consumed significantly less fat, red meat, and total calories than did the RMR subjects, while the RMSC subjects consumed significantly less total calories than did the RMR subjects. Serum LDL-C was significantly higher in the AR subjects when compared to that of the RMR subjects, while serum HDL-C was significantly higher for both the AR and RMR subjects when compared to that obtained for the RMSC subjects. The nutritional inadequacy would appear to separate the AR from the RMR, and, thus, the exercise training performed by the athletes at the time of the present investigation alone does not appear to be the major factor associated with athletic amenorrhea.
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Snyder AC, Dvorak LL, Roepke JB. Influence of dietary iron source on measures of iron status among female runners. Med Sci Sports Exerc 1989; 21:7-10. [PMID: 2927304 DOI: 10.1249/00005768-198902000-00002] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The purpose of the present investigation was to determine whether female runners who consume a modified vegetarian diet are predisposed to iron deficiency. Two groups of female runners who were matched for age, weight, aerobic capacity, miles run per week, and number of pregnancies were obtained for this study. One group (N = 9) regularly consumed a modified vegetarian diet (MV, less than 100 g red meat.wk-1), while the other group (N = 9) consumed a diet which included red meat (RM). Serum ferritin values were significantly (P less than 0.05) lower for the MV group (X +/- SE, 7.4 +/- 1.4 ng.100 ml-1) than for the RM group (19.8 +/- 4.2 ng.100 ml-1). Total iron binding capacity (TIBC) of the serum was also significantly different between the two groups of subjects (MV, 366.5 +/- 12.2 micrograms.100 ml-1; RM, 327.2 +/- 9.6 micrograms.100 ml-1). While dietary iron intake was comparable for the two groups (MV, 14.7 +/- 2.0 mg.d-1; RM, 14.0 +/- 2.2 mg.d-1, the bioavailability of the dietary iron was significantly different (MV, 0.66 +/- 0.08 mg.d-1; RM, 0.91 +/- 0.10 mg.d-1). As the presence of heme iron (from meat, fish, and poultry) increases the bioavailability of dietary iron, the results of the present investigation suggest that vegetarian athletes have altered iron status due to the form in which their dietary iron is consumed.
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Barr JT, Lapple WJ, Snyder AC, Hsu JC, Tuovinen OH. Evaluation of contact lenses by microbial enumeration and protein determination. AMERICAN JOURNAL OF OPTOMETRY AND PHYSIOLOGICAL OPTICS 1988; 65:476-80. [PMID: 3046366 DOI: 10.1097/00006324-198806000-00007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Contact lenses worn for varying periods of time (from 1 to 48 months) were subjected to microbiological examination by plate counts and protein determination. Seventy percent of the lenses displayed bacterial colony counts below 120 colony-forming units (CFU)/lens, 28 percent were in the range of 140 to 9060 CFU/lens, and one lens was contaminated with greater than 6 x 10(4) CFU/lens. Fungal contaminants were detected in three lens specimens in the range of 220 to 760 CFU/lens. Protein accumulation showed wide variation of up to 1.2 mg of protein per lens. Statistical analysis indicated highly significant associations (p less than 0.001) between the bacterial colony counts obtained with three different media. Some significant associations were found between the protein concentration and bacterial counts. The data did not indicate statistically significant relations between the above variables and either the water content or the length of wear of the contact lenses.
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Foster C, Snyder AC, Thompson NN, Kuettel K. Normalization of the blood lactate profile in athletes. Int J Sports Med 1988; 9:198-200. [PMID: 3410624 DOI: 10.1055/s-2007-1025005] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The power output-blood lactate or velocity-blood lactate relationship, the lactate "profile", is a widely used method for the evaluation of athletes. Recent observations have suggested a shift in the blood lactate profile when athletes are fatigued, as at training camps. This study was designed to determine whether the blood lactate profile could be corrected for progressive muscle glycogen depletion by normalizing for the peak exercise blood lactate concentration. Ten well-trained subjects performed incremental cycle ergometer exercise followed by supramaximal exercise (Wingate test) following 3 days of usual and 3 days of heavier than usual training. Following heavier than usual training, blood lactate accumulation was reduced during submaximal exercise such that the power output associated with a lactate concentration of 4 mM was significantly increased (3.08 vs 3.51 W/kg). The maximal blood lactate concentration was also reduced (14.8 vs 12.7 mM) although average supramaximal power output was unchanged (9.03 vs 8.92 W/kg). When the submaximal blood lactate concentrations were normalized for the maximal blood lactate concentration, there were no significant differences in the power output associated with 20% (2.6 vs 2.7 W/kg), 25% (3.1 vs 3.2 W/kg), or 30% (3.3 vs 3.5 W/kg) of maximal lactate. The results suggest that normalization based on peak exercise blood lactate may be a useful strategy for circumventing one of the primary practical barriers to the use of the blood lactate profile in athletes.
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