scholarly journals Reproducibility of cardiorespiratory and performance responses to exercise in hypoxia

2016 ◽  
Author(s):  
Ben J Lee ◽  
Charles D Thake
Keyword(s):  
Performance Measures ◽  
Correlation Coefficients ◽  
Time Trial ◽  
Time Of Day ◽  
Intra Class Correlation ◽  
Future Studies ◽  
Performance Time ◽  
Hypoxic Conditions ◽  
And Performance ◽  
Hypoxic Exercise

Background. Knowledge of the variance in physiological performance measures between repeated trials can inform whether familiarization sessions are necessary prior to intervention studies. The purpose of this study was to assess the reliability of cardiorespiratory and exercise performance measures during both steady state hypoxic exercise and a preloaded 16.1 km hypoxic time trial. Methods. Eighteen male participants (age, 22 ± 4 years; height, 1.77 ± 0.04 meters; body mass, 76.8 kg; estimated body fat and VO2peak = 3.50 ± 0.60 L.min-1) were divided into three groups. Reliability of responses (HR, SPO2 , VO2 , VCO2 , VE and respiratory exchange ratio; RER) to the HST (FIO2 0.14; 15 minutes rest, 60 minutes cycling at 50% normoxic VO2peak) was assessed across 3 repeat trials (HST 1, 2 and 3, n = 6). Reliability of the preloaded time trial (pTT; 15 min rest, 40 minutes cycling at 50% normoxic VO2peak, 16.1km time trial) was assessed across 3 repeat normoxic (N; FIO2 ≈ 0.21; n=6) and 3 repeat hypoxic (FIO2 ≈ 0.14; n = 6) trials. All exercise trials were undertaken at the same time of day, following exercise and dietary controls, 7 days apart. Results. Intra-class correlation coefficients (ICC’s) for mean and peak HR, SpO2 , VE , VO2 , VCO2 and blood lactate within each trial were improved from HST1 to HST2 (mean data: 0.99, 0.95, 0.75, 0.62, 0.70, 0.90; peak data: 0.98, 0.96, 0.64, 0.69, 0.74, 0.75) to HST2 and HST3 (ICC = 0.99, 0.97, 0.82, 0.85, 0.87 and 0.96 respectively). The reliability for time to pTT completion was improved following one trial, and the CV (test 2 vs. 3) was similar under normoxic (CV = 0.62) and hypoxic conditions (CV = 0.63). Conclusion. Cardiorespiratory responses to the HST were reproducible and the pTT performance time reliable in both normoxia and hypoxia. Since the reproducibility of the measurements in HST trials and reliability of pTT improved between the second and third trials, two familiarization visit are recommended prior to employing these protocols in future studies.

scholarly journals Reproducibility of cardiorespiratory and performance responses to exercise in hypoxia

2016 ◽  
Author(s):  
Ben J Lee ◽  
Charles D Thake
Keyword(s):  
Performance Measures ◽  
Correlation Coefficients ◽  
Time Trial ◽  
Time Of Day ◽  
Intra Class Correlation ◽  
Future Studies ◽  
Performance Time ◽  
Hypoxic Conditions ◽  
And Performance ◽  
Hypoxic Exercise

Background. Knowledge of the variance in physiological performance measures between repeated trials can inform whether familiarization sessions are necessary prior to intervention studies. The purpose of this study was to assess the reliability of cardiorespiratory and exercise performance measures during both steady state hypoxic exercise and a preloaded 16.1 km hypoxic time trial. Methods. Eighteen male participants (age, 22 ± 4 years; height, 1.77 ± 0.04 meters; body mass, 76.8 kg; estimated body fat and VO2peak = 3.50 ± 0.60 L.min-1) were divided into three groups. Reliability of responses (HR, SPO2 , VO2 , VCO2 , VE and respiratory exchange ratio; RER) to the HST (FIO2 0.14; 15 minutes rest, 60 minutes cycling at 50% normoxic VO2peak) was assessed across 3 repeat trials (HST 1, 2 and 3, n = 6). Reliability of the preloaded time trial (pTT; 15 min rest, 40 minutes cycling at 50% normoxic VO2peak, 16.1km time trial) was assessed across 3 repeat normoxic (N; FIO2 ≈ 0.21; n=6) and 3 repeat hypoxic (FIO2 ≈ 0.14; n = 6) trials. All exercise trials were undertaken at the same time of day, following exercise and dietary controls, 7 days apart. Results. Intra-class correlation coefficients (ICC’s) for mean and peak HR, SpO2 , VE , VO2 , VCO2 and blood lactate within each trial were improved from HST1 to HST2 (mean data: 0.99, 0.95, 0.75, 0.62, 0.70, 0.90; peak data: 0.98, 0.96, 0.64, 0.69, 0.74, 0.75) to HST2 and HST3 (ICC = 0.99, 0.97, 0.82, 0.85, 0.87 and 0.96 respectively). The reliability for time to pTT completion was improved following one trial, and the CV (test 2 vs. 3) was similar under normoxic (CV = 0.62) and hypoxic conditions (CV = 0.63). Conclusion. Cardiorespiratory responses to the HST were reproducible and the pTT performance time reliable in both normoxia and hypoxia. Since the reproducibility of the measurements in HST trials and reliability of pTT improved between the second and third trials, two familiarization visit are recommended prior to employing these protocols in future studies.

scholarly journals Reproducibility of cardiorespiratory and cellular responses to steady state exercise in hypoxia and preloaded cycling time trial performance reliability in normoxia and acute hypoxia

2015 ◽  
Author(s):  
Ben J Lee ◽  
Charles D Thake
Keyword(s):  
Stress Test ◽  
Acute Hypoxia ◽  
Correlation Coefficients ◽  
Time Trial ◽  
Cellular Responses ◽  
Time Of Day ◽  
Cycling Time Trial ◽  
Hypoxic Conditions ◽  
Before And After ◽  
Cycling Time

Background. The purpose of this study was to assess the reproducibility of cardiorespiratory and cellular (monocyte heat shock protein 70; mHSP70) responses to a fixed load hypoxic stress test (HST) and the reliability of a pre-loaded 16.1km cycling time trial (pTT) conducted under both normoxic and hypoxic conditions. Methods. Eighteen participants (age, 22 ± 4 years; height, 1.77 ± 0.04 meters; body mass, 76.8 kg; estimated body fat and VO2peak = 3.50 ± 0.60 L.min-1) were divided into three groups. Reliability of responses (HR, SPO2, VO2, VCO2, VE and RER) to the HST (FIO2 0.14; 15 minutes rest, 60 minutes cycling at 50% normoxic VO2peak) was assessed across 3 repeat trials (HST 1, 2 and 3, n = 6); mHSP70 was measured via flow cytometry before and after each HST (n = 5); resting HSP was also quantified on 4 separate occasions (n=5). Reliability of the pTT (15 min rest, 40 minutes cycling at 50% normoxic VO2peak) was assessed across 3 repeat normoxic (N; FIO2 ≈ 0.21; n=6) and 3 repeat hypoxic (FIO2 ≈ 0.14; n = 6) trials. All exercise trials were undertaken at the same time of day, following exercise and dietary controls, 7 days apart. Results. Intra-class correlation coefficients (ICC’s) for mean and peak HR, SpO2, VE , VO2 , VCO2 and BLa within each trial were improved from HST1 to HST2 (mean data: 0.99, 0.95, 0.75, 0.62, 0.70, 0.90; peak data: 0.98, 0.96, 0.64, 0.69, 0.74, 0.75) to HST2 and HST3 (ICC = 0.99, 0.97, 0.82, 0.85, 0.87 and 0.96 respectively). mHSP70 was a reproducible at rest without (ICC > 0.95) and with HSTs conducted in the previous 7 days (ICC > 0.95), with no difference in pre to post increases in mHSP70 observed between tests. The reliability for time to pTT completion was improved following one trial, and the CV (test 2 vs. 3) was similar under normoxic (CV = 0.62) and hypoxic conditions (CV = 0.63). Conclusion. Cardiorespiratory and cellular responses to the HST were reproducible and the pTT performance time reliable in both N and H. Since the reproducibility of the measurements in HST trials and reliability of pTT improved between the second and third trials one familiarization visit is recommended prior to employing these protocols in future studies.

scholarly journals The Effect of Dietary Nitrate Supplementation on Physiology and Performance in Trained Cyclists

2017 ◽  
Vol 12 (5) ◽  
pp. 684-689 ◽  
Author(s):  
Joseph A. McQuillan ◽  
Deborah K. Dulson ◽  
Paul B. Laursen ◽  
Andrew E. Kilding
Keyword(s):  
Time Trial ◽  
Crossover Design ◽  
Moderate Intensity ◽  
Beetroot Juice ◽  
Double Blind ◽  
Dietary Nitrate ◽  
Performance Time ◽  
Exercise Economy ◽  
Nitrate Supplementation ◽  
And Performance

Purpose:To determine the effect of dietary nitrate (NO3 –) supplementation on physiology and performance in well-trained cyclists after 6–8 d of NO3 – supplementation.Methods:Eight competitive male cyclists (mean ± SD age 26 ± 8 y, body mass 76.7 ± 6.9 kg, VO2peak 63 ± 4 mL · kg–1 · min–1) participated in a double-blind, placebo-controlled, crossover-design study in which participants ingested 70 mL of beetroot juice containing ~4 mmol NO3 – (NIT) or a NO3 –-depleted placebo (PLA), each for 8 d. Replicating pretreatment measures, participants undertook an incremental ramp assessment to determine VO2peak and first (VT1) and second (VT2) ventilatory thresholds on d 6 (NIT6 and PLA6), moderate-intensity cycling economy on d 7 (NIT7 and PLA7), and a 4-km time trial (TT) on d 8 (NIT8 and PLA8).Results:Relative to PLA, 6 d of NIT supplementation produced unclear effects for VO2peak (mean ± 95% confidence limit: 1.8% ± 5.5%) and VT1 (3.7% ± 12.3%) and trivial effects for both VT2 (–1.0% ± 3.0%) and exercise economy on d 7 (–1.0% ± 1.6%). However, effects for TT performance time (–0.7% ± 0.9%) and power (2.4% ± 2.5%) on d 8 were likely beneficial.Conclusions:Despite mostly unclear outcomes for standard physiological determinants of performance, 8 d of NO3 – supplementation resulted in likely beneficial improvements to 4-km TT performance in well-trained male endurance cyclists.

Acute Sodium Ingestion Before Exercise Increases Voluntary Water Consumption Resulting in Preexercise Hyperhydration and Improvement in Exercise Performance in the Heat

2015 ◽  
Vol 25 (5) ◽  
pp. 456-462 ◽  
Author(s):  
David M. Morris ◽  
Joshua R. Huot ◽  
Adam M. Jetton ◽  
Scott R. Collier ◽  
Alan C. Utter
Keyword(s):  
Water Consumption ◽  
Exercise Performance ◽  
Time Trial ◽  
Favorable Effect ◽  
Hydration Status ◽  
Performance Time ◽  
Sodium Ingestion ◽  
Improve Exercise Performance ◽  
And Performance ◽  
Sodium Consumption

Dehydration has been shown to hinder performance of sustained exercise in the heat. Consuming fluids before exercise can result in hyperhydration, delay the onset of dehydration during exercise and improve exercise performance. However, humans normally drink only in response to thirst, which does not result in hyperhydration. Thirst and voluntary fluid consumption have been shown to increase following oral ingestion or infusion of sodium into the bloodstream. We measured the effects of acute sodium ingestion on voluntary water consumption and retention during a 2-hr hydration period before exercise. Subjects then performed a 60-min submaximal dehydration ride (DR) followed immediately by a 200 kJ performance time trial (PTT) in a warm (30 °C) environment. Water consumption and retention during the hydration period was greater following sodium ingestion (1380 ± 580 mL consumed, 821 ± 367 ml retained) compared with placebo (815 ± 483 ml consumed, 244 ± 402 mL retained) and no treatment (782 ± 454 ml consumed, 148 ± 289 mL retained). Dehydration levels following the DR were significantly less after sodium ingestion (0.7 ± 0.6%) compared with placebo (1.3 ± 0.7%) and no treatment (1.6 ± 0.4%). Time to complete the PTT was significantly less following sodium consumption (773 ± 158 s) compared with placebo (851 ± 156 s) and no treatment (872 ± 190 s). These results suggest that voluntary hyperhydration can be induced by acute consumption of sodium and has a favorable effect on hydration status and performance during subsequent exercise in the heat.

Treatment of Test Anxiety by Applied Relaxation and Cue-Controlled Relaxation

1980 ◽  
Vol 46 (3_suppl) ◽  
pp. 1287-1296 ◽  
Author(s):  
Billy A. Barrios ◽  
Earl J. Ginter ◽  
Joseph J. Scalise ◽  
Francis G. Miller
Keyword(s):  
Test Anxiety ◽  
Performance Measures ◽  
Post Treatment ◽  
Self Report ◽  
Future Studies ◽  
Applied Relaxation ◽  
Anxiety Behavior ◽  
Behavior Scale ◽  
And Performance

Several procedures have been used to produce relaxation and thus reduce test anxiety. The purpose of this study was to compare three types of treatment of test anxiety: applied relaxation, cognitive cue-controlled relaxation, and conditioned cue-controlled relaxation. Also, cognitive and conditioning explanations for the two cue-controlled treatments were explored Subjects were female undergraduates ( N = 18) scoring in the upper 15% of the distribution of 1,055 students completing the Suinn Test Anxiety Behavior Scale. Pre- and post-treatment scores on several self-report and performance measures of anxiety were used to evaluate the efficiency of each technique. Most statistically significant changes were obtained in the applied relaxation group. No significant differences were found between the two cue-controlled procedures used in the study. Recommendations concerning future investigations are discussed; specific procedural modifications for future studies are outlined.

scholarly journals The reliability of physiological and performance data obtained during a long distance simulated triathlon laboratory test

2019 ◽  
Vol 8 (3) ◽  
pp. 25-32
Author(s):  
Kate Margaret Luckin
Keyword(s):  
Blood Lactate ◽  
Perceived Exertion ◽  
Correlation Coefficients ◽  
Rating Of Perceived Exertion ◽  
Long Distance ◽  
Task Representation ◽  
Intra Class Correlation ◽  
Physiological Variables ◽  
And Performance ◽  
High Level

The aim of this study was to investigate the reliability of a newly developed long distance (LD) simulated triathlon for testing performance and physiological changes in LD triathletes. Ten trained LD triathletes (mean ± standard deviation: age 34.1 ± 5.0 years, body mass 69.07 ± 13.89 kg) completed two separate trials of a simulated LD triathlon consisting of a 1500 m swim, a 60 minute cycle at 60% of power at VO2max and a 20 minute run at 70% of velocity at VO2max. Performance (time, pace, power and rating of perceived exertion) and physiological (economy of movement (oxygen cost and energy consumption), blood lactate and heart rate)variables were measured throughout the simulated LD triathlon. Coefficient of variations (CV %) and intra class correlation coefficients (ICC) were calculated to determine reliability. The current study displayed a high level of reliability, with moderate to excellent ICC measurements for performance and physiological variables (ICC 0.62 – 0.99). All physiological variables, except blood lactate, demonstrated CV values < 10%. In conclusion, the newly developed LD simulated triathlon has a high level of task representation for LD triathletes and can accurately assess performance changes in a research setting.

Effects of Time of Day on Pacing in a 4-km Time Trial in Trained Cyclists

2020 ◽  
Vol 15 (10) ◽  
pp. 1455-1459
Author(s):  
Emma K. Zadow ◽  
James W. Fell ◽  
Cecilia M. Kitic ◽  
Jia Han ◽  
Sam S. X. Wu
Keyword(s):  
Time Trial ◽  
Time Of Day ◽  
Tympanic Temperature ◽  
Mean Power ◽  
Physiological Factors ◽  
Cycling Time Trial ◽  
Improved Performance ◽  
And Performance ◽  
Power Outputs ◽  
Mean Power Output

Context: Time of day has been shown to impact athletic performance, with improved performance observed in the late afternoon–early evening. Diurnal variations in physiological factors may contribute to variations in pacing selection; however, research investigating time-of-day influence on pacing is limited. Purpose: To investigate the influence of time-of-day on pacing selection in a 4-km cycling time trial (TT). Methods: Nineteen trained male cyclists (mean [SD] age 39.0 [10.7] y, height 1.8 [0.1] m, body mass 78.0 [9.4] kg, VO2max 62.1 [8.7] mL·kg−1·min−1) completed a 4-km TT on 5 separate occasions at 08:30, 11:30, 14:30, 17:30, and 20:30. All TTs were completed in a randomized order, separated by a minimum of 2 d and maximum of 7 d. Results: No time-of-day effects were observed in pacing as demonstrated by similar power outputs over 0.5-km intervals (P = .78) or overall mean power output (333.0 [38.9], 339.8 [37.2], 335.5 [31.2], 336.7 [35.2], and 334.9 [35.7] W; P = .45) when TTs were performed at 08:30, 11:30, 14:30, 17:30, and 20:30. Preexercise tympanic temperature demonstrated a time-of-day effect (P < .001), with tympanic temperature higher at 14:30 and 17:30 than at 08:30 and 11:30. Conclusion: While a biological rhythm was present in tympanic temperature, pacing selection and performance when completing a 4-km cycling TT were not influenced by time of day. The findings suggest that well-trained cyclists can maintain a robust pacing strategy for a 4-km TT regardless of time of the day.

scholarly journals Pedal force asymmetries and performance during a 20-km cycling time trial

Kinesiology ◽  
2016 ◽  
Vol 48 (2) ◽  
pp. 193-199 ◽  
Author(s):  
Rodrigo R. Bini ◽  
Tiago C. Jacques ◽  
Carlos H. Sperb ◽  
Fábio J. Lanferdini ◽  
Marco A. Vaz
Keyword(s):  
Effect Size ◽  
Force Production ◽  
Time Trial ◽  
Cycling Time Trial ◽  
Pedal Force ◽  
Performance Time ◽  
Competitive Cyclists ◽  
And Performance ◽  
The Relationship ◽  
Cycling Time

It is unclear if applying larger or more symmetrical pedal forces leads to better performance in cycling. The aims of this study were to assess the relationship between pedal force production and performance in a cycling time trial and to evaluate the relationship between asymmetries in pedal force production and performance. Fifteen competitive cyclists/triathletes performed a 20 km cycling time trial on a cycle trainer while bilateral forces applied to the pedals were recorded along with total time. Total forces applied to the pedals were computed and converted into dominant and non-dominant forces using a leg preference inventory. Pedal force asymmetries ranged from 43% (in favour of the dominant limb) to 34% (in favour of the non-dominant limb). The relationship between total pedal force (averaged from both pedals) and performance time was small (r=-.32, effect size=.66) as well as the association between the asymmetry indices and performance time (r=.01, effect size=.06). In conclusion, applying large forces on the pedals and balancing pedal force application between the dominant and non-dominant limbs did not lead to better performance in this cycling time trial.

Sildenafil improves cardiac output and exercise performance during acute hypoxia, but not normoxia

2006 ◽  
Vol 100 (6) ◽  
pp. 2031-2040 ◽  
Author(s):  
Andrew R. Hsu ◽  
Kimberly E. Barnholt ◽  
Nicolas K. Grundmann ◽  
Joseph H. Lin ◽  
Stewart W. McCallum ◽  
...  
Keyword(s):  
Cardiac Output ◽  
Exercise Performance ◽  
Acute Hypoxia ◽  
Arterial Oxygen Saturation ◽  
Time Trial ◽  
Work Capacity ◽  
Work Rate ◽  
Arterial Oxygen ◽  
And Performance ◽  
Hypoxic Exercise

Sildenafil causes pulmonary vasodilation, thus potentially reducing impairments of hypoxia-induced pulmonary hypertension on exercise performance at altitude. The purpose of this study was to determine the effects of sildenafil during normoxic and hypoxic exercise. We hypothesized that 1) sildenafil would have no significant effects on normoxic exercise, and 2) sildenafil would improve cardiac output, arterial oxygen saturation (SaO2), and performance during hypoxic exercise. Ten trained men performed one practice and three experimental trials at sea level (SL) and simulated high altitude (HA) of 3,874 m. Each cycling test consisted of a set-work-rate portion (55% work capacity: 1 h SL, 30 min HA) followed immediately by a time trial (10 km SL, 6 km HA). Double-blinded capsules (placebo, 50, or 100 mg) were taken 1 h before exercise in a randomly counterbalanced order. For HA, subjects also began breathing hypoxic gas (12.8% oxygen) 1 h before exercise. At SL, sildenafil had no effects on any cardiovascular or performance measures. At HA, sildenafil increased stroke volume (measured by impedance cardiography), cardiac output, and SaO2 during set-work-rate exercise. Sildenafil lowered 6-km time-trial time by 15% ( P < 0.05). SaO2 was also higher during the time trial ( P < 0.05) in response to sildenafil, despite higher work rates. Post hoc analyses revealed two subject groups, sildenafil responders and nonresponders, who improved time-trial performance by 39% ( P < 0.05) and 1.0%, respectively. No dose-response effects were observed. During cycling exercise in acute hypoxia, sildenafil can greatly improve cardiovascular function, SaO2, and performance for certain individuals.

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