Precision of ventilatory and gas exchange alterations as a predictor of the anaerobic threshold

Powers, Scott K.; Dodd, Stephen; Garner, Robert P.

doi:10.1007/bf00433388

Cited by 45 publications

(25 citation statements)

References 14 publications

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“…On the day of the data collection run, subjects warmed up for 5 min running at a freely chosen speed. After the warm-up, the 1-h run began with treadmill running at the predetermined speed and continued with a 5-min stage of unmonitored running allowing sufficient time to reach a stable oxygen uptake and providing some accommodation time to treadmill running (Candau et al 1998;Costill 1967;Powers et al 1984). Following the first 5 min, runners completed a stage including 2-min segments of running at their preferred stride frequency (PSF), then 4 and 8% above and below PSF.…”

Section: Methodsmentioning

confidence: 99%

Preferred and optimal stride frequency, stiffness and economy: changes with fatigue during a 1-h high-intensity run

2007

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Metabolic cost of submaximal running at constant speed is influenced by various factors including fatigue and kinematic characteristics. Metabolic costs typically drift upwards during extended running while stride characteristics often shift away from initial. When non-fatigued, experienced runners naturally optimize stride frequency in a manner that minimizes oxygen uptake. An initial objective was to determine whether runners demonstrate a similar self-optimizing capability when fatigued where stride characteristics have perhaps shifted away from the initial state. A secondary objective involved measurement of vertical and leg stiffness characteristics as a potential explanation for frequency changes with fatigue. We hypothesized that runners decrease stride frequency and stiffness with fatigue while optimizing these characteristics to minimize metabolic cost. Sixteen experienced runners completed a near maximal effort 1-h treadmill run at a constant speed. Preferred and optimal stride frequencies (PSF and OSF) were measured near the beginning and end of the hour run using frequencies +/-4 and +/-8% around PSF. From vertical force data recorded throughout the run, leg and vertical stiffness were determined. As expected, oxygen uptake significantly increased during the run from 45.9 to 47.4 ml kg(-1) min(-1) (P = 0.004). There was no difference between preferred and optimal stride frequencies at the beginning or the end of running (P = 0.978), however both PSF and OSF significantly decreased from 1.45 to 1.43 Hz (P = 0.026). All runners self-optimized stride frequency at the beginning and end of one-hour of running despite changes of optimal stride frequency. Stiffness and stride frequency changes were subject specific with some runners exhibiting little to no change. No clear relationship of frequency or stiffness changes to economy was found.

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Section: Methodsmentioning

confidence: 99%

Preferred and optimal stride frequency, stiffness and economy: changes with fatigue during a 1-h high-intensity run

2007

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“…The ratio of the anaerobic threshold to the maximal oxygen consumption has been described as 50-60% in normal subjects 14,15,18) and approximately 70% in cardiac patients. 19,20) Previous reports have demonstrated that the anaerobic threshold was an accurate and reproducible index to classify the severity of an impairment of cardiac function.…”

Section: Methodsmentioning

confidence: 99%

Oxygen Utilization and Hemodynamic Response during Exercise in Children after Fontan Procedure.

Miyairi¹,

Kawauchi²,

Takamoto³

et al. 1998

Jpn Heart J

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SUMMARYEight patients, 9.1 to 16.5 years of age, were studied 2.8 to 8.5 years after Fontan operation. Oxygen utilization was determined during upright bicycle exercise. The cardiac index and stroke index were measured by echocardiography and the anaerobic threshold was determined. The results were compared with 10 patients after surgical closure of the atrial septal defect. Anaerobic threshold (AT) in Fontan patients was lower than in the control subjects. Oxygen consumption at each stage of exercise was significantly lower in the Fontan group compared with the control subjects. From the beginning of exercise until AT, the increase in stroke index was lower in the Fontan patients than in the control subjects. After that point, the stroke index decreased significantly in the Fontan patients while it remained almost at the same level in the control subjects. Significant correlations were observed between the oxygen pulses and the stroke index at AT both in the control and Fontan groups. These results suggest that impaired exercise capacity in Fontan patients is mainly due to a subnormal response of the stroke index at AT and to the decreased response of the stroke index and the heart rate at the maximal workload. (Jpn Heart J 1998; 39: 659-669)

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“…Recently, there have been several studies wherein VT is not always consistent with LT (GREEN et al, 1983;SIMoN et al, 1983;POWERS et al, 1984;GLADDEN et al, 1985), and which are negative about the cause-effect relationship between LT and VT (HAGBERG et al, 1982;HUGHES et al, 1982). Only two studies (GREEN et al, 1983;GLADDEN et al, 1985) reported a disassociation of LT and VT, using the objective method for determining both LT and VT. GREEN et al (1983) showed that VT occurred at a significantly higher work rate than LT, and GLADDEN et al (1985) showed that agreement between both was poor (r=0.29).…”

Section: Methodsmentioning

confidence: 99%

Comparison of objective methods for determining ventilatory threshold.

et al. 1988

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This study was undertaken to compare and re-examine the relation of lactate threshold (LT) and ventilatory threshold (VT), using six objective determination methods proposed previously. Twenty-one young male subjects performed a cycle exercise test in which the work rate was increased by 150 kg m every 2 min up to his limit of volitional fatigue. Through each test, gas exchange parameter measurements were made every 1 min (every 30s at nearly maximal level), and the venous blood samples were taken from a warmed ear lobe at each work rate for determining blood lactate concentration. LT and its variance were determined by the intersecting straight lines regression. LT ranged from 0.72 to 1.401/min in terms of V02 , and the mean value of S.D. for each LT was about 0.11/min. Each objective method for determining VT used in this study was based on the simple modelling of the criterion for visual detection of VT, that is the non-linear increase in VE or the systematic increase in VE/Voz. When the relationship between LT and VT was examined, VT by the objective methods based on determining minimum value of VE/Voz showed relatively high consistency with LT. Of 16-20 individuals out of all 21 subjects, there were VT within LT + 0.2 in Voz. It is concluded that VE/Voz is a more sensitive index for detecting VT than VE in the gas exchange parameters, and the objective VT determination method based on minimum value of VE/Voz could facilitate estimation of LT within an error of + 0.2 1/mmn Voz in most normal individuals.

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Precision of ventilatory and gas exchange alterations as a predictor of the anaerobic threshold

Cited by 45 publications

References 14 publications

Preferred and optimal stride frequency, stiffness and economy: changes with fatigue during a 1-h high-intensity run

Preferred and optimal stride frequency, stiffness and economy: changes with fatigue during a 1-h high-intensity run

Oxygen Utilization and Hemodynamic Response during Exercise in Children after Fontan Procedure.

Comparison of objective methods for determining ventilatory threshold.

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