Maximal Oxygen Uptake Is Achieved in Hypoxia but Not Normoxia during an Exhaustive Severe Intensity Run (original) (raw)
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Influence of Acute Moderate Hypoxia on Time to Exhaustion at vV˙O 2 max in Unacclimatized Runners
International Journal of Sports Medicine, 2003
Eight unacclimatized long-distance runners performed, on a level treadmill, an incremental test to determine the maximal oxygen uptake (V O 2 max) and the minimal velocity eliciting V O 2 max (vV O 2 max) in normoxia (N) and acute moderate hypoxia (H) corresponding to an altitude of 2400 m (PIO 2 of 109 mmHg). Afterwards, on separate days, they performed two all-out constant velocity runs at vV O 2 max in a random order (one in N and the other in H). The decrease in V O 2 max between N and H showed a great degree of variability amongst subjects as V O 2 max decreased by 8.9 4 ml min -1 kg -1 in H vs. N conditions (-15.3 6.3 % with a range from -7.9 % to -23.8 %). This decrease in V O 2 max was proportional to the value of V O 2 max (V O 2 max vs. delta V O 2 max N-H, r = 0.75, p = 0.03). The time run at vV O 2max was not affected by hypoxia (483 122 vs. 506 148 s, in N and H, respectively, p = 0.37). However, the greater the decrease in vV O 2 max during hypoxia, the greater the runners increased their time to exhaustion at vV O 2 max (vV O 2 max N-H vs. tlim @vV O 2 max N-H, r = -0.75, p = 0.03). In conclusion, this study showed that there was a positive association between the extent of decrease in vV O 2 max , and the increase in run time at vV O 2 max in hypoxia.
Effect of intermittent hypoxia on oxygen uptake during submaximal exercise in endurance athletes
European Journal of Applied Physiology, 2004
The purpose of the present study was to clarify the following: (1) whether steady state oxygen uptake (V _O 2 ) during exercise decreases after short-term intermittent hypoxia during a resting state in trained athletes and (2) whether the change in V _O 2 during submaximal exercise is correlated to the change in endurance performance after intermittent hypoxia. Fifteen trained male endurance runners volunteered to participate in this study. Each subject was assigned to either a hypoxic group (n=8) or a control group (n=7). The hypoxic group spent 3 h per day for 14 consecutive days in normobaric hypoxia [12.3 (0.2)% inspired oxygen]. The maximal and submaximal exercise tests, a 3,000-m time trial, and resting hematology assessments at sea level were conducted before and after intermittent normobaric hypoxia. The athletes in both groups continued their normal training in normoxia throughout the experiment. V _O 2 during submaximal exercise in the hypoxic group decreased significantly (P<0.05) following intermittent hypoxia. In the hypoxic group, the 3,000-m running time tended to improve (P=0.06) after intermittent hypoxia, but not in the control group. Neither peak V _O 2 nor resting hematological parameters were changed in either group. There were significant (P<0.05) relationships between the change in the 3,000-m running time and the change in V _O 2 during submaximal exercise after intermittent hypoxia. The results from the present study suggest that the enhanced running economy resulting from intermittent hypoxia could, in part, contribute to improved endurance performance in trained athletes.
2005
Few studies have investigated the influence of hypoxia on the primary and the slow components [10, 23] of oxygen uptake (V Ç O 2 ) kinetics. Regarding the primary component, a consensus in the literature does exist. A slower V Ç O 2 kinetics (that is a longer primary component time constant t) has been always reported under moderate hypoxia (inspired gas concentration or FIO 2 < 0.15) compared with normoxia at the same absolute work rate for both moderate (< ventilatory threshold, VT) and heavy (> VT) exercise intensities . Based on the relationship between O 2 supply in working muscles and V Ç O 2 kinetics, some authors have concluded that the mechanisms determining the V Ç O 2 -response at the onset of constant work-rate heavy exercise would be related to the rate of O 2 delivery to the working muscles. However, others suggested that the Abstract This study examined the influence of moderate hypoxia on the oxygen uptake (V Ç O 2 ) kinetic response (primary time constant and slow component amplitude) during moderate and heavy cycle exercise in twenty-seven male subjects with various training status. Nine endurance trained (21.5 2.6 yr), nine sprint trained (22.9 5.7 yr), and nine untrained controls (24.0 4.4 yr) completed incremental tests to exhaustion in normoxia (inspired gas concentration or FIO 2 = 21% O 2 ) and hypoxia (FIO 2 = 13% O 2 ) to establish the FIO 2 -specific ventilatory threshold (VT) and maximal VO 2 . Subsequently, the subjects performed repeated constant work rate cycling exercises during 7 min at moderate intensity (80 % of FIO 2 -specific VT) and heavy intensity (midway between the FIO 2 specific VT and maximal VO 2 ). Pulmonary gas exchange was measured breath-by-breath during all exercise sessions. For both moderate and heavy intensities, the time constant of the primary VO 2 component was significantly (p < 0.05) slowed by~25 to 30 % in hypoxia compared to normoxia to the same extent in the three groups. Hypoxia produced a more important decrease in the amplitude of the slow component in endurance athletes (± 36%) than in sprinters (± 30 %) and controls (± 12%). These results suggest that both primary and slow components of VO 2 kinetics during the adjustment to moderateand heavy-intensity exercise are sensitive to hypoxia while training status tended to modulate partly the slow component amplitude.
2021
Pramkratok W, Yimlamai T. Effects of Acute Hypoxia on PsychoPhysiological Response and Muscle Oxygenation during Incremental Running Exercise. JEPonline 2021;24(3):44-54. The purpose of this study was to determine the effects of acute hypoxia exposure on physiological and perceptual responses, and muscle oxygenation during maximal incremental running exercise. Seven male elite rugby sevens players volunteered to participate in this study. In a randomized crossover design, the subjects completed two incremental running exercise tests either under normoxia (FiO2 = 20.9%) or after a 3-hr exposure to hypoxia (FiO2 = 14.5%). During both exercise conditions, pulmonary gas exchange was measured using a portable Metamax3B, rating of perceived exertion (RPE) using Borg's (6-20) scale, and muscle oxygenation at the quadriceps using a portable near-infrared spectroscopy. The results indicated that VO2peak, VEpeak, HRpeak, vVO2peak, and time to exhaustion were significantly lower (P<0.05...
Determinants of maximal oxygen uptake in moderate acute hypoxia in endurance athletes
European Journal of Applied Physiology, 2007
The factors determining maximal oxygen consumption were explored in eight endurance trained subjects (TS) and eight untrained subjects (US) exposed to moderate acute normobaric hypoxia. Subjects performed maximal incremental tests at sea level and simulated altitudes (1,000, 2,500, 4,500 m). Heart rate (HR), stroke volume (SV), cardiac output ð _ QÞ; arterialized oxygen saturation ðSa 0 O 2 Þ; oxygen uptake ð _ VO 2max Þ; ventilation ( _ VE; expressed in normobaric conditions) were measured. At maximal exercise, ventilatory equivalent ð _ VE= _ VO 2max Þ; O 2 transport ð _ QaO 2max Þ and O 2 extraction (O 2 ER max ) were calculated. In TS, _ Q max remained unchanged despite a significant reduction in HR max at 4,500 m. SV max remained unchanged. _ VE max decreased in TS at 4,500 m, _ VE= _ VO 2max was lower in TS and greater at 4,500 m vs. sea level in both groups. Sa¢O 2max decreased at and above 1,000 m in TS and 2,500 m in US, O 2 ER max increased at 4,500 m in both groups. _ QaO 2max decreased with altitude and was greater in TS than US up to 2,500 m but not at 4,500 m. _ VO 2max decreased with altitude but the decrement ðD _ VO 2max Þ was larger in TS at 4,500 m. In both groups D _ VO 2max in moderate hypoxia was correlated with D _ QaO 2max : Several differences between the two groups are probably responsible for the greater D _ VO 2max in TS at 4,500 m : (1) the relative hypoventilation in TS as shown by the decrement in _ VE max at 4,500 m (2) the greater _ QaO 2max decrement in TS due to a lower Sa¢O 2max and unchanged _ Q max 3) the smaller increase in O 2 ER max in TS, insufficient to compensate the decrease in _ QaO 2max :
International Journal of Environmental Research and Public Health, 2020
The literature suggests that acute hypobaric (HH) and normobaric (NH) hypoxia exposure elicits different physiological responses. Only limited information is available on whether maximal cardiorespiratory exercise test outcomes, performed on either the treadmill or the cycle ergometer, are affected differently by NH and HH. A focused literature review was performed to identify relevant studies reporting cardiorespiratory responses in well-trained male athletes (individuals with a maximal oxygen uptake, VO2max > 50 mL/min/kg at sea level) to cycling or treadmill running in simulated acute HH or NH. Twenty-one studies were selected. The exercise tests in these studies were performed in HH (n = 90) or NH (n = 151) conditions, on a bicycle ergometer (n = 178) or on a treadmill (n = 63). Altitudes (simulated and terrestrial) varied between 2182 and 5400 m. Analyses (based on weighted group means) revealed that the decline in VO2max per 1000 m gain in altitude was more pronounced in ac...
The response of trained athletes to six weeks of endurance training in hypoxia or normoxia
International journal of sports medicine, 2003
This study was performed to investigate the effect of training under simulated hypoxic conditions. Hypoxia training was integrated into the normal training schedule of 12 endurance trained cyclists. Athletes were randomly assigned to two groups and performed three additional training bouts per week for six weeks on a bicycle ergometer. One group (HG) trained at the anaerobic threshold under hypoxic conditions (corresponding to an altitude of 3200 m) while the control group (NG) trained at the same relative intensity at 560 m. Preceding and following the six training weeks, performance tests were performed under normoxic and hypoxic conditions. Normoxic and hypoxic .VO2max, maximal power output as well as hypoxic work-capacity were not improved after the training period. Testing under hypoxic conditions revealed a significant increase in oxygen saturation (SpO 2, from 67.1 +/- 2.3 % to 70.0 +/- 1.7 %) and in maximal blood lactate concentration (from 7.0 to 9.1 mM) in HG only. Ferriti...
Rapidity of response to hypoxic conditions during exercise
International journal of sports physiology and performance, 2013
Previous studies have found decreases in arterial oxygen saturation to be temporally linked to reductions in power output (PO) during time-trial (TT) exercise. The purpose of this study was to determine whether preexercise desaturation (estimated from pulse oximetry [SpO2]), via normobaric hypoxia, would change the pattern of PO during a TT. The authors tested the hypothesis that the starting PO of a TT would be reduced in the EARLY trial secondary to a reduced SpO2 but would not be reduced in LATE until ~30 s after the start of the TT. Eight trained cyclists/triathletes (4 male, 4 female) performed 3 randomly ordered 3-km TTs while breathing either room air (CONTROL) or hypoxic air administered 3 min before the start of the TT (EARLY) or at the beginning of the TT (LATE). There was no effect of hypoxia on PO during the first 0.3 km of either the EARLY or the LATE trial compared with CONTROL, although there was a significant decrease in pre-TT SpO2 in EARLY vs CONTROL and LATE. The ...
International journal of sports medicine, 2007
We aimed to evaluate 1) the altitude where maximal heart rate (HR (max)) decreases significantly in both trained and untrained subjects in moderate acute hypoxia, and 2) if the HR (max) decrease could partly explain the drop of V.O (2max). Seventeen healthy males, nine trained endurance athletes (TS) and eight untrained individuals (US) were studied. Subjects performed incremental exercise tests at sea level and at 5 simulated altitudes (1000, 1500, 2500, 3500, 4500 meters). Power output (PO), heart rate (HR), arterial oxygen saturation (SaO (2)), oxygen uptake (V.O (2)), arterialized blood pH and lactate were measured. Both groups showed a progressive reduction in V.O (2max). The decrement in HR (max) (DeltaHR (max)) was significant from 1000 m for TS and 2500 m for US and more important in TS than US (at 1500 m and 3500 m). At maximal exercise, TS had a greater reduction in SaO (2) (DeltaSaO (2)) at each altitude. DeltaHR (max) observed in TS was correlated with DeltaSaO (2). When...
Decrease in oxygen uptake at the end of a high-intensity submaximal running in humans
International journal of sports medicine, 2002
The purpose of the present study was to examine oxygen consumption (VO(2) ) kinetics during severe-intensity running exercise through a four-phase model that considered a decrease in VO(2) at the end of the exercise in light of previous research in which this decrease was only noticed. After determination of maximal oxygen consumption VO(2) max), thirteen highly trained males performed a square-wave running to exhaustion at approximately 95 % of VO(2) max on a level treadmill. VO(2) and ventilatory gas exchange variables were determined breath-by-breath. Computerised non-linear regression techniques incorporating exponential and linear terms were used to describe VO(2) and ventilatory gas exchange variable responses. In contrast with the classical 3-component model that describes the increase in VO(2) for severe-intensity exercise, we observed a 4(th) phase characterised by a significant decrease in VO(2) before exhaustion (slope of VO(2)-time relationship significantly different fr...