Cardiorespiratory Response and Power Output During Submaximal Exercise in Normobaric Versus Hypobaric Hypoxia: A Pilot Study Using a Specific Chamber that Controls Environmental Factors

Impact ◽  
2021 ◽  
Vol 2021 (8) ◽  
pp. 55-57
Author(s):  
Toshihiro Takezawa ◽  
Shohei Dobashi ◽  
Katsuhiro Koyama
Keyword(s):  
Environmental Factors ◽  
Power Output ◽  
High Intensity ◽  
Hypobaric Hypoxia ◽  
Atmospheric Oxygen ◽  
Physiological Responses ◽  
Barometric Pressure ◽  
High Intensity Exercise ◽  
Fraction Of Inspired Oxygen ◽  
Inspired Oxygen

2021.—Many previous studies have examined hypoxia-induced physiological responses using various conditions, e.g., artificially reduced atmospheric oxygen concentration [normobaric hypoxia (NH) condition] or low barometric pressure at a mountain [hypobaric hypoxia (HH) condition]. However, when comparing the results from these previous studies conducted in artificial NH and HH including real high altitude, we must consider the possibility that environmental factors, such as temperature, humidity, and fraction of inspired carbon dioxide, might affect the physiological responses. Therefore, we examined cardiorespiratory responses and exercise performances during low- to high-intensity exercise at a fixed heart rate (HR) in both NH and HH using a specific chamber where atmospheric oxygen concentration and barometric pressure as well as the abovementioned environmental factors were precisely controlled. Ten well-trained university students (eight males and two females) performed the exercise test consisting of two 20-minute submaximal pedaling at the intensity corresponding to 50% (low) and 70% (high) of their HR reserve, under three conditions [NH (fraction of inspired oxygen, 0.135; barometric pressure, 754 mmHg), HH (fraction of inspired oxygen, 0.209; barometric pressure, 504 mmHg), and normobaric normoxia (NN; fraction of inspired oxygen, 0.209; barometric pressure, 754 mmHg)]. Peripheral oxygen saturation (SpO2) to estimate arterial oxygen saturation and partial pressure of end-tidal carbon dioxide (PETCO2) were monitored throughout the experiment. SpO2, PETCO2, and power output at fixed HRs (i.e., pedaling efficiency) in NH and HH were all significantly lower than those in NN. Moreover, high-intensity exercise in HH induced greater decreases in SpO2 and power output than did high-intensity exercise in NH (NH vs. HH; SpO2, 78.2% - 5.0% vs. 75.1% - 7.1%; power output, 120.7 - 24.9 W vs. 112.4 - 23.2 W, both p < 0.05). However, high-intensity exercise in HH induced greater increases in PETCO2 than did high-intensity exercise in NH (NH vs. HH; 54.2 - 5.9mmHg vs. 57.2 - 3.4 mmHg, p < 0.01). These results suggest that physiological responses and power output at a fixed HR during hypoxic exposure might depend on the method used to generate the hypoxic condition.

EFFECT OF INTERMITTENT HIGH INTENSITY EXERCISE ON POWER OUTPUT, BLOOD AMMONIA AND LACTATE

1992 ◽  
Vol 24 (Supplement) ◽  
pp. S57
Author(s):  
T. Michael ◽  
R. Robertson ◽  
D. Onenstein ◽  
P. Nixon ◽  
D. Cassinelli ◽  
...  
Keyword(s):  
Power Output ◽  
High Intensity ◽  
High Intensity Exercise ◽  
Blood Ammonia

The Maximum Sustainable Power Output Following Intolerance During High Intensity Exercise

2009 ◽  
Vol 41 ◽  
pp. 45
Author(s):  
Scott R. Murgatroyd ◽  
Carrie Ferguson ◽  
Susan A. Ward ◽  
Richard M. Cubbon ◽  
Harry B. Rossiter
Keyword(s):  
Power Output ◽  
High Intensity ◽  
High Intensity Exercise ◽  
Sustainable Power

Factors Influencing Blood Alkalosis and Other Physiological Responses, Gastrointestinal Symptoms, and Exercise Performance Following Sodium Citrate Supplementation: A Review

2020 ◽  
pp. 1-19
Author(s):  
Charles S. Urwin ◽  
Rodney J. Snow ◽  
Dominique Condo ◽  
Rhiannon Snipe ◽  
Glenn D. Wadley ◽  
...  
Keyword(s):  
Short Duration ◽  
Exercise Performance ◽  
High Intensity ◽  
Sodium Citrate ◽  
Physiological Responses ◽  
Gastrointestinal Symptoms ◽  
High Intensity Exercise ◽  
Similar Frequency ◽  
Gi Symptoms ◽  
Very High

This review aimed to identify factors associated with (a) physiological responses, (b) gastrointestinal (GI) symptoms, and (c) exercise performance following sodium citrate supplementation. A literature search identified 33 articles. Observations of physiological responses and GI symptoms were categorized by dose (< 500, 500, and > 500 mg/kg body mass [BM]) and by timing of postingestion measurements (in minutes). Exercise performance following sodium citrate supplementation was compared with placebo using statistical significance, percentage change, and effect size. Performance observations were categorized by exercise duration (very short < 60 s, short ≥ 60 and ≤ 420 s, and longer > 420 s) and intensity (very high > 100% VO2max and high 90–100% VO2max). Ingestion of 500 mg/kg BM sodium citrate induced blood alkalosis more frequently than < 500 mg/kg BM, and with similar frequency to >500 mg/kg BM. The GI symptoms were minimized when a 500 mg/kg BM dose was ingested in capsules rather than in solution. Significant improvements in performance following sodium citrate supplementation were reported in all observations of short-duration and very high–intensity exercise with a 500 mg/kg BM dose. However, the efficacy of supplementation for short-duration, high-intensity exercise is less clear, given that only 25% of observations reported significant improvements in performance following sodium citrate supplementation. Based on the current literature, the authors recommend ingestion of 500 mg/kg BM sodium citrate in capsules to induce alkalosis and minimize GI symptoms. Supplementation was of most benefit to performance of short-duration exercise of very high intensity; further investigation is required to determine the importance of ingestion duration and timing.

Caffeine, performance, and metabolism during repeated Wingate exercise tests

1998 ◽  
Vol 85 (4) ◽  
pp. 1502-1508 ◽  
Author(s):  
F. Greer ◽  
C. McLean ◽  
T. E. Graham
Keyword(s):  
Power Output ◽  
High Intensity ◽  
Anaerobic Metabolism ◽  
Exercise Bout ◽  
High Intensity Exercise ◽  
Intense Exercise ◽  
Short Term ◽  
Exercise Tests ◽  
Negative Effect ◽  
Epinephrine Concentration

Investigations examining the ergogenic and metabolic influence of caffeine during short-term high-intensity exercise are few in number and have produced inconsistent results. This study examined the effects of caffeine on repeated bouts of high-intensity exercise in recreationally active men. Subjects ( n = 9) completed four 30-s Wingate (WG) sprints with 4 min of rest between each exercise bout on two separate occasions. One hour before exercise, either placebo (Pl; dextrose) or caffeine (Caf; 6 mg/kg) capsules were ingested. Caf ingestion did not have any effect on power output (peak or average) in the first two WG tests and had a negative effect in the latter two exercise bouts. Plasma epinephrine concentration was significantly increased 60 min after Caf ingestion compared with Pl; however, this treatment effect disappeared once exercise began. Caf ingestion had no significant effect on blood lactate, O2 consumption, or aerobic contribution at any time during the protocol. After the second Wingate test, plasma NH3concentration increased significantly from the previous WG test and was significantly higher in the Caf trial compared with Pl. These data demonstrate no ergogenic effect of caffeine on power output during repeated bouts of short-term, intense exercise. Furthermore, there was no indication of increased anaerobic metabolism after Caf ingestion with the exception of an increase in NH3 concentration.

scholarly journals Effects of mild whole body hypothermia on self-paced exercise performance

2018 ◽  
Vol 125 (2) ◽  
pp. 479-485
Author(s):  
Steven A. H. Ferguson ◽  
Neil D. Eves ◽  
Brian D. Roy ◽  
Gary J. Hodges ◽  
Stephen S. Cheung
Keyword(s):  
Rectal Temperature ◽  
Exercise Performance ◽  
Power Output ◽  
High Intensity ◽  
Mild Hypothermia ◽  
Oxygenation Index ◽  
Time Trial ◽  
Oxygen Availability ◽  
High Intensity Exercise ◽  
Whole Body

This study examined self-paced, high-intensity exercise during mild hypothermia and whether hyperoxia might offset any potential impairment. Twelve trained males each completed 15-km time trials in three environmental conditions: Neutral (23°C, [Formula: see text] 0.21), Cold (0°C, [Formula: see text] 0.21), and Cold+Hyper (0°C, [Formula: see text] 0.40). Cold and Cold+Hyper trials occurred after a 0.5°C drop in rectal temperature. Rectal temperature was higher ( P ≤ 0.016) throughout Neutral compared with Cold and Cold+Hyper; Cold had a higher ( P ≤ 0.035) rectal temperature than Cold+Hyper from 2.5 to 7.5 km, and hyperoxia did not alter thermal sensation or comfort. Oxyhemoglobin saturation decreased from ~98% to ~94% with Neutral and Cold, but was maintained at ~99% in Cold+Hyper ( P < 0.01). Cerebral tissue oxygenation index (TOI) was higher in Neutral than in Cold throughout the time trial (TT) ( P ≤ 0.001), whereas Cold+Hyper were unchanged ( P ≥ 0.567) from Neutral by 2.5 km. Muscle TOI was maintained in Cold+Hyper compared with Neutral and was higher ( P ≤ 0.046) than Cold throughout the entire TT. Power output during Cold (246 ± 41 W) was lower than Neutral (260 ± 38 W) at all 2.5-km intervals ( P ≤ 0.012) except at 12.5 km. Power output during Cold+Hyper (256 ± 42 W) was unchanged ( P ≥ 0.161) from Neutral throughout the TT, and was higher than Cold from 7.5 km onward. Average cadence was higher in Neutral (93 ± 8 rpm) than in either Cold or Cold+Hyper (Cold: 89 ± 7 and Cold+Hyper: 90 ± 8 rpm, P = 0.031). In conclusion, mild hypothermia reduced self-paced exercise performance; hyperoxia during mild hypothermia restored performance to thermoneutral levels, likely due to maintenance of oxygen availability rather than any thermogenic benefit. NEW & NOTEWORTHY We examined self-paced, high-intensity exercise with 0.5°C rectal temperature decreases in a 0°C ambient environment, along with whether hyperoxia could offset any potential impairment. During a 15-km time trial, power output was lower with hypothermia than with thermoneutral. However, with hypothermia, hyperoxia of [Formula: see text] = 0.40 restored power output despite there being no thermophysiological improvement. Hypothermia impairs exercise performance, whereas hyperoxia likely restored performance due to maintenance of oxygen availability rather than any thermogenic benefit.

Sign in / Sign up

Export Citation Format

Share Document