Measurements of the anaerobic work capacity in a group of highly trained runners.
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Biomedical subjects
Publications and source records attributed to D C Poole.
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The purpose of this study was to evaluate the effects of continuous and interval training on changes in lactate and ventilatory thresholds during incremental exercise. Seventeen males were assigned to one of three training groups: group 1:55 min continuous exercise at approximately 50% maximum O2 consumption (VO2max); group 2: 35 min continuous exercise at approximately 70% VO2max; and group 3: 10 X 2-min intervals at approximately 105% VO2max interspersed with rest intervals of 2 min. All of the subjects were tested and trained on a cycle ergometer 3 day/wk for 8 wk. Lactate threshold (LT) and ventilatory threshold (VT) (in addition to maximal exercise measures) were determined using a standard incremental exercise test before and after 4 and 8 wk of training. VO2max increased significantly in all groups with no statistically significant differences between the groups. Increases (+/- SE) in LT (ml O2 X min-1) for group 1 (569 +/- 158), group 2 (584 +/- 125), and group 3 (533 +/- 88) were significant (P less than 0.05) and of the same magnitude. VT also increased significantly (P less than 0.05) in each group. However, the increase in VT (ml O2 X min-1) for group 3 (699 +/- 85) was significantly greater (P less than 0.05) than the increases in VT for group 1 (224 +/- 52) and group 2 (404 +/- 85). For group 1, the posttraining increase in LT was significantly greater than the increase in VT (P less than 0.05). We conclude that both continuous and interval training were equally effective in augmenting LT, but interval training was more effective in elevating VT.(ABSTRACT TRUNCATED AT 250 WORDS)
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The purpose of this investigation was to determine whether the ventilatory gas exchange threshold (Tvent) changes significantly during the first 1-3 weeks of endurance training. Six men were studied during 3 weeks of training, which consisted of pedaling on a cycle ergometer 6 d X wk 30 min per session at 70% of pretraining VO2max. At the end of each week, VO2max, Tvent, and maximal and submaximal heart rates were determined during an incremental exercise test on the cycle ergometer. Constant-load submaximal exercise blood lactate concentrations were determined during training sessions on Monday, Wednesday, and Friday of each week of training. Tvent did not change significantly during the 3 weeks of training (+ 0.091 X min-1; P greater than 0.05). In contrast, significant changes occurred in all other training indexes measured. VO2max increased by 0.36 1 X min-1 (P less than 0.05) after just 2 weeks of training and did not change further after 3 weeks. Significant reductions (40-45%; P less than 0.05) in blood lactate levels during training sessions occurred by the middle of the 2nd week of training. Decreases in maximal (approximately 11 bt X min-1) and submaximal (approximately 14 bt X min-1) exercise heart rates after 1 week of training were significant (P less than 0.05). The results demonstrate that changes in Tvent lag behind alterations in several other cardiovascular and metabolic parameters in response to endurance training.(ABSTRACT TRUNCATED AT 250 WORDS)
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Vertigo or disequilibrium occurring in patients after concussive and nonconcussive head trauma may be due to a pathologic perilymphatic fistula from the inner ear through the oval and round window areas of the middle ear. Of 33 patients who had successful grafting of the fistulous area at middle ear exploration, 32 had resolution of vertigo, and 12 of 23 who had an associated hearing loss had improved hearing. Perilymphatic fistulas associated with vertigo and hearing loss after head trauma can be diagnosed with great certainty and are surgically curable in the great majority of cases. Patients with post-concussive syndrome, whose symptoms include vertigo or disequilibrium, should have a thorough otologic evaluation for the possibility of a perilymphatic fistula.
The effect of a pattern of exercise and dietary modifications, which was designed to produce alterations in the muscle glycogen content, on the capacity to perform anaerobic exercise was investigated. Six young male subjects worked to exhaustion on a bicycle ergometer at a supramaximal work load equivalent to 104 +/- 5% of VO2max after a normal diet, after a carbohydrate (CHO)-free diet following prolonged exhausting exercise, and after a high-CHO diet. This regimen has previously been shown to cause changes in the glycogen content of the working muscle. Mean work time for subjects on the first test was 4.87 +/- 1.07 min (mean +/- SD). After the low-CHO diet, the time for which work could be maintained was reduced in an increase to 3.32 +/- 0.93 min, whereas administration of the high-CHO diet resulted in an increase to 6.65 +/- 1.39 min. The resting blood lactate concentration was lower than normal following the low-CHO diet and higher than normal following the high-CHO diet. Post exercise blood lactate concentrations reached a peak between 2 and 6 min after exhaustion and again were lower (8.60 +/- 1.58 mmol/l) after the low-CHO diet and higher (12.86 +/- 1.42 mmol/l) after the high-CHO diet than after performing the same intensity of work to exhaustion on a normal diet (11.66 +/- 1.16 mmol/l). The rate of lactate accumulation appeared to be approximately the same during exercise under all three dietary conditions. If this is the case, it suggests that the alterations in endurance capacity do not result from changes in the rate of anaerobic glycolytic energy production, but possibly from a change in the total capacity of the system.
Analysis of the latency, amplitude, and rise characteristics of the stapedius reflex as demonstrated on a strip recorder revealed abnormalities in patients with vestibular neuronitis and other vertigo syndromes. The findings in vestibular neuronitis, acute labyrinthitis, perilymphatic fistulas, Meniere's disease, cerebrovascular insufficiency, and metabolic vertigo are described. Alterations in the stapedius reflex included increase in latency, decrease in amplitude, stepping of the rise, and absence of the reflex. This study suggests that absence of the reflex can be associated with vertigo as well as with acoustic neuromas and other retrocochlear lesions. The findings of abnormalities in vestibular neuronitis support a brain-stem localization as the site of lesion in this disease.
A new application of the glycerin test in the diagnosis of post-traumatic perilymphatic fistulas is described. Temporary disappearance of abnormal responses to the fistula and Quix tests and improvement in the hearing occurred. The glycerin test was useful in confirming the diagnosis of post-traumatic perilymphatic fistula in 13 patients in whom fistulas were found at middle ear exploration.
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The onset and duration of positive responses to the glycerin test were studied in 28 patients with Menière's disease who had positive responses to the test. The responses were measured for three hours at 30-minute intervals after the ingestion of glycerin. Positive responses were found as early as 30 minutes after ingestion of glycerin. The responses had often become negative by two to three hours. Testing of patients with Menière's disease only at the end of a three-hour interval after ingestion of glycerin will produce a large proportion of false-negative responses, as evidenced by a 39 per cent negative response rate three hours after ingestion of glycerin.