The effect of intermittent hypobaric hypoxic exposure and sea level training on submaximal economy in well-trained swimmers and runners

2008 ◽  
Vol 104 (2) ◽  
pp. 328-337 ◽  
Author(s):  
Martin J. Truijens ◽  
Ferran A. Rodríguez ◽  
Nathan E. Townsend ◽  
James Stray-Gundersen ◽  
Christopher J. Gore ◽  
...  
Keyword(s):  
Sea Level ◽  
Repeated Measures ◽  
Hypobaric Hypoxia ◽  
Lactate Concentration ◽  
Hypoxic Exposure ◽  
Double Blind ◽  
Intermittent Hypobaric Hypoxia ◽  
Post Test ◽  
Double Blind Design ◽  
Level Training

To evaluate the effect of intermittent hypobaric hypoxia combined with sea level training on exercise economy, 23 well-trained athletes (13 swimmers, 10 runners) were assigned to either hypobaric hypoxia (simulated altitude of 4,000–5,500 m) or normobaric normoxia (0–500 m) in a randomized, double-blind design. Both groups rested in a hypobaric chamber 3 h/day, 5 days/wk for 4 wk. Submaximal economy was measured twice before (Pre) and after (Post) the treatment period using sport-specific protocols. Economy was estimated both from the relationship between oxygen uptake (V̇o2) and speed, and from the absolute V̇o2 at each speed using sport-specific protocols. V̇o2 was measured during the last 60 s of each (3–4 min) stage using Douglas bags. Ventilation (V̇e), heart rate (HR), and capillary lactate concentration ([La−]) were measured during each stage. Velocity at maximal V̇o2 (velocity at v̇o2max) was used as a functional indicator of changes in economy. The average V̇o2 for a given speed of the Pre values was used for Post test comparison using a two-way, repeated-measures ANOVA. Typical error of measurement of V̇o2 was 4.7% (95% confidence limits 3.6–7.1), 3.6% (2.8–5.4), and 4.2% (3.2–6.9) for speeds 1, 2, and 3, respectively. There was no change in economy within or between groups (ANOVA interaction P = 0.28, P = 0.23, and P = 0.93 for speeds 1, 2, and 3). No differences in submaximal HR, [La−], V̇e, or velocity at V̇o2max were found between groups. It is concluded that 4 wk of intermittent hypobaric hypoxia did not improve submaximal economy in this group of well-trained athletes.

Effects of acute caffeine withdrawal on habituated male runners

1994 ◽  
Vol 76 (3) ◽  
pp. 1043-1048 ◽  
Author(s):  
R. K. Hetzler ◽  
N. Warhaftig-Glynn ◽  
D. L. Thompson ◽  
E. Dowling ◽  
A. Weltman
Keyword(s):  
Repeated Measures ◽  
Lactate Threshold ◽  
Substrate Utilization ◽  
Caffeine Intake ◽  
Loading Dose ◽  
Testing Session ◽  
O2 Uptake ◽  
Double Blind ◽  
Caffeine Withdrawal ◽  
Double Blind Design

This study investigated the effects of caffeine withdrawal on six trained caffeine-habituated male runners: age 29.8 +/- 5.8 (SD) yr, height 180.4 +/- 5.4 cm, weight 77.3 +/- 6.7 kg, maximal O2 uptake 63.0 +/- 5.4 ml.kg-1.min-1, and daily caffeine intake 674 +/- 128 mg. The subjects received a loading dose (5 mg/kg body wt) of caffeine 48 h before each testing session. They were then given (using a repeated-measures double-blind design) additional doses of caffeine (5 mg/kg body wt) or a placebo 36, 24, 12, and 2 h before testing. They ran at a velocity corresponding to their lactate threshold for 60 min in a caffeine withdrawal or caffeinated condition. Caffeine withdrawal resulted in no significant differences in absolute O2 uptake, O2 uptake relative to maximal O2 uptake, respiratory exchange ratios, or free fatty acid concentrations. Glycerol concentrations were significantly attenuated in the withdrawal condition. No significant differences were revealed in calculated substrate utilization. It was concluded that caffeine withdrawal significantly affects lipolysis but not substrate utilization during prolonged running.

Performance of runners and swimmers after four weeks of intermittent hypobaric hypoxic exposure plus sea level training

2007 ◽  
Vol 103 (5) ◽  
pp. 1523-1535 ◽  
Author(s):  
Ferran A. Rodríguez ◽  
Martin J. Truijens ◽  
Nathan E. Townsend ◽  
James Stray-Gundersen ◽  
Christopher J. Gore ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Sea Level ◽  
Oxygen Transport ◽  
Hypobaric Hypoxia ◽  
Ventilatory Threshold ◽  
Controlled Trial ◽  
Intervention Group ◽  
Sport Performance ◽  
Hypoxic Exposure ◽  
Significant Difference

This double-blind, randomized, placebo-controlled trial examined the effects of 4 wk of resting exposure to intermittent hypobaric hypoxia (IHE, 3 h/day, 5 days/wk at 4,000–5,500 m) or normoxia combined with training at sea level on performance and maximal oxygen transport in athletes. Twenty-three trained swimmers and runners completed duplicate baseline time trials (100/400-m swims, or 3-km run) and measures for maximal oxygen uptake (V̇O2max), ventilation (V̇Emax), and heart rate (HRmax) and the oxygen uptake at the ventilatory threshold (V̇O2 at VT) during incremental treadmill or swimming flume tests. Subjects were matched for sex, sport, performance, and training status and divided randomly between hypobaric hypoxia (Hypo, n = 11) and normobaric normoxia (Norm, n = 12) groups. All tests were repeated within the first (Post1) and third weeks (Post2) after the intervention. Time-trial performance did not improve in either group. We could not detect a significant difference between groups for a change in V̇O2max, V̇Emax, HRmax, or V̇O2 at VT after the intervention (group × test interaction P = 0.31, 0.24, 0.26, and 0.12, respectively). When runners and swimmers were considered separately, Hypo swimmers appeared to increase V̇O2max (+6.2%, interaction P = 0.07) at Post2 following a precompetition taper and increased V̇O2 at VT (+8.9 and +12.1%, interaction P = 0.007 and 0.006, at Post1 and Post2). We conclude that this “dose” of IHE was not sufficient to improve performance or oxygen transport in this heterogeneous group of athletes. Whether there are potential benefits of this regimen for specific sports or training/tapering strategies may require further study.

Effects of Four Weeks of Intermittent Hypobaric Hypoxia on Sea Level Running and Swimming Performance

2004 ◽  
Vol 36 (Supplement) ◽  
pp. S338 ◽  
Author(s):  
Fernando A. Rodriguez ◽  
Martin J. Truijens ◽  
Nathan E. Townsend ◽  
Emily R. Martini ◽  
James Stray-Gundersen ◽  
...  
Keyword(s):  
Sea Level ◽  
Hypobaric Hypoxia ◽  
Swimming Performance ◽  
Intermittent Hypobaric Hypoxia ◽  
Level Running

scholarly journals Cardiovascular Risk Is Increased in Miner’s Chronic Intermittent Hypobaric Hypoxia Exposure From 0 to 2,500 m?

2021 ◽  
Vol 12 ◽  
Author(s):  
Andrés Pedreros-Lobos ◽  
Rodrigo Calderón-Jofré ◽  
Daniel Moraga ◽  
Fernando A. Moraga
Keyword(s):  
Sea Level ◽  
Aerobic Capacity ◽  
Hypobaric Hypoxia ◽  
Venous Blood ◽  
Overweight And Obesity ◽  
Experimental Population ◽  
Moderate Altitude ◽  
Intermittent Hypobaric Hypoxia ◽  
Increased Risk ◽  
Significant Difference

Over the past 40 years, mining activities in Chile have relocated miners who normally live at sea level to work at high altitudes. This results in a form of chronic intermittent hypobaric hypoxia (CIHH) characterized by alternating periods of work at high altitude and rest periods at sea level. Previous studies performed in our laboratory showed that aerobic capacity is reduced at 3,800 m, even when oxygen content is maintained. Our study aimed to determine the corporal composition, food intake, maximum oxygen uptake, and concentration of high sensitivity C reactive protein (hsCRP) in an acclimatized miner population that work from 0 to 2,500 m with CIHH exposure over 4 years. All miners recruited for our study were operators of heavy trucks with CIHH for over 4 years (shiftwork 7*7 days), and our experimental population was composed of 54 miners at sea level, 61 at 1,600 m, and 38 at 2,500 m. All evaluations were performed on the 3rd or 4th day of diurnal shiftwork. To determine corporal composition, we measured weight and height (to calculate body mass index, BMI), skinfolds (to calculate body fatty, BF), and waist circumference (WC); maximal aerobic capacity was evaluated using a ramp-incremental cycling to exhaustion protocol and a venous blood sample before the exercise test to measure (hsCRP) via an ELISA test. We found higher values of BMI, BF, and WC, in the miners’ population but observed no significant difference between populations. We found a decrease in VO2 of 11.6% at 1,600 m and 25.9% at 2,500 m compared to miners at sea level. An increase in (hsCRP) at 1,600 and 2,500 m regards sea level. We observed a high prevalence of overweight and obese subjects, which was related to the ad libitum availability of food and low physical activity (sedentarism). We found that work capacity was maintained despite a decreased VO2 max at moderate altitude. However, overweight and obesity support an increased risk of cardiometabolic disease in miner’s which is unrelated to altitude. In contrast, an increased hsCRP level could be associated with increased inflammatory mechanisms at 1,600 and 2,500 m.

Six weeks of oral Echinacea purpurea supplementation does not enhance the production of serum erythropoietin or erythropoietic status in recreationally active males with above-average aerobic fitness

2019 ◽  
Vol 44 (7) ◽  
pp. 791-795
Author(s):  
Tyler D. Martin ◽  
Michael S. Green ◽  
Malcolm T. Whitehead ◽  
Timothy P. Scheett ◽  
Michael J. Webster ◽  
...  
Keyword(s):  
Aerobic Fitness ◽  
Repeated Measures ◽  
Hemoglobin Concentration ◽  
Echinacea Purpurea ◽  
Matched Pair ◽  
Mean Corpuscular Hemoglobin ◽  
Double Blind ◽  
Factorial Anova ◽  
Double Blind Design ◽  
Serum Erythropoietin

The purpose of this study was to investigate the effect of 6 weeks of oral Echinacea purpurea supplementation on serum erythropoietin (EPO) and erythropoietic status. Twenty-four males (mean ± SE; age = 25.2 ± 1.4 years, height = 178.1 ± 1.4 cm, body mass = 78.1 ± 1.6 kg, body fat = 12.7 ± 0.9%, maximal oxygen uptake = 52.9 ± 0.9 mL·kg−1·min−1) were randomly grouped using a matched-pair, double-blind design and self-administered 8000 mg·day−1 of either E. purpurea (n = 12) or placebo (n = 12) for 42 consecutive days. Blood samples were collected prior to supplementation (day 0) and every 2 weeks during the supplementation period (days 14, 28, and 42) and were analyzed for EPO, red blood cell count, hemoglobin concentration, hematocrit, mean corpuscular volume, and mean corpuscular hemoglobin concentration. Separate 2 × 4 (group × time) factorial ANOVA with repeated measures on time were used to determine statistical differences with significance set at p ≤ 0.05. There were no significant interaction, group, or time effects observed for EPO or erythropoietic status markers for any of the measurement points (p ≤ 0.05). The present study indicated that 6 weeks of oral E. purpurea supplementation in recreationally active males with above average aerobic fitness did not enhance EPO or erythropoietic status. These findings are in contrast with previous reports of E. purpurea supplementation in untrained participants with average fitness levels, but consistent with observations in trained endurance athletes.

scholarly journals The Effects of High Doses of Caffeine on Maximal Strength and Muscular Endurance in Athletes Habituated to Caffeine

Nutrients ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1912 ◽  
Author(s):  
Michal Wilk ◽  
Michal Krzysztofik ◽  
Aleksandra Filip ◽  
Adam Zajac ◽  
Juan Del Coso
Keyword(s):  
Body Mass ◽  
Repeated Measures ◽  
Bench Press ◽  
Muscle Endurance ◽  
Experimental Session ◽  
Maximal Strength ◽  
Double Blind ◽  
Significant Difference ◽  
Endurance Tests ◽  
Double Blind Design

Background: The main goal of this study was to assess the acute effects of the intake of 9 and 11 mg/kg/ body mass (b.m.) of caffeine (CAF) on maximal strength and muscle endurance in athletes habituated to caffeine. Methods: The study included 16 healthy strength-trained male athletes (age = 24.2 ± 4.2 years, body mass = 79.5 ± 8.5 kg, body mass index (BMI) = 24.5 ± 1.9, bench press 1RM = 118.3 ± 14.5 kg). All participants were habitual caffeine consumers (4.9 ± 1.1 mg/kg/b.m., 411 ± 136 mg of caffeine per day). This study had a randomized, crossover, double-blind design, where each participant performed three experimental sessions after ingesting either a placebo (PLAC) or 9 mg/kg/b.m. (CAF-9) and 11 mg/kg/b.m. (CAF-11) of caffeine. In each experimental session, participants underwent a 1RM strength test and a muscle endurance test in the bench press exercise at 50% 1RM while power output and bar velocity were measured in each test. Results: A one-way repeated measures ANOVA revealed a significant difference between PLAC, CAF-9, and CAF-11 groups in peak velocity (PV) (p = 0.04). Post-hoc tests showed a significant decrease for PV (p = 0.04) in the CAF-11 compared to the PLAC group. No other changes were found in the 1RM or muscle endurance tests with the ingestion of caffeine. Conclusion: The results of the present study indicate that high acute doses of CAF (9 and 11 mg/kg/b.m.) did not improve muscle strength nor muscle endurance in athletes habituated to this substance.

Increased serum erythropoietin but not red cell production after 4 wk of intermittent hypobaric hypoxia (4,000–5,500 m)

2006 ◽  
Vol 101 (5) ◽  
pp. 1386-1393 ◽  
Author(s):  
Christopher J. Gore ◽  
Ferran A. Rodríguez ◽  
Martin J. Truijens ◽  
Nathan E. Townsend ◽  
James Stray-Gundersen ◽  
...  
Keyword(s):  
Transferrin Receptor ◽  
Hypobaric Hypoxia ◽  
Soluble Transferrin Receptor ◽  
Double Blind ◽  
Hypoxia Exposure ◽  
Intermittent Hypobaric Hypoxia ◽  
Collegiate Level ◽  
Norm Group ◽  
Hemoglobin Mass ◽  
Serum Erythropoietin

This study tested the hypothesis that athletes exposed to 4 wk of intermittent hypobaric hypoxia exposure (3 h/day, 5 days/wk at 4,000–5,500 m) or double-blind placebo increase their red blood cell volume (RCV) and hemoglobin mass (Hbmass) secondary to an increase in erythropoietin (EPO). Twenty-three collegiate level athletes were measured before (Pre) and after (Post) the intervention for RCV via Evans blue (EB) dye and in duplicate for Hbmassusing CO rebreathing. Hematological indexes including EPO, soluble transferrin receptor, and reticulocyte parameters were measured on 8–10 occasions spanning the intervention. The subjects were randomly divided among hypobaric hypoxia (Hypo, n = 11) and normoxic (Norm, n = 12) groups. Apart from doubling EPO concentration 3 h after hypoxia there was no increase in any of the measures for either Hypo or Norm groups. The mean change in RCV from Pre to Post for the Hypo group was 2.3% (95% confidence limits = −4.8 to 9.5%) and for the Norm group was −0.2% (−5.7 to 5.3%). The corresponding changes in Hbmasswere 1.0% (−1.3 to 3.3%) for Hypo and −0.3% (−2.6 to 3.1%) for Norm. There was good agreement between blood volume (BV) from EB and CO: EB BV = 1.03 × CO BV + 142, r2= 0.85, P < 0.0001. Overall, evidence from four independent techniques (RCV, Hbmass, reticulocyte parameters, and soluble transferrin receptor) suggests that INTERMITTENT HYPOBARIC HYPOXIA EXPOSURE did not accelerate erythropoiesis despite the increase in serum EPO.

Effects of Chromium Picolinate Supplementation on Body Composition, Strength, and Urinary Chromium Loss in Football Players

1994 ◽  
Vol 4 (2) ◽  
pp. 142-153 ◽  
Author(s):  
Stephan P. Clancy ◽  
Priscilla M. Clarkson ◽  
Michael E. DeCheke ◽  
Kazunori Nosaka ◽  
Patty S. Freedson ◽  
...  
Keyword(s):  
Body Composition ◽  
Repeated Measures ◽  
Dynamic Strength ◽  
Weight Lifting ◽  
Chromium Picolinate ◽  
Football Players ◽  
Double Blind ◽  
Significant Group ◽  
Double Blind Design ◽  
Urinary Chromium

The effects of 9 weeks of daily chromium supplementation (200μg Cr as picolinate) were investigated in a double-blind design in football players during spring training. Testing was done pre-, mid-, and postsupplementation on the following criterion measures: urinary chromium excretion, girth and skinfold measures, percent body fat and lean body mass, and isometric and dynamic strength. With the exception of 2 variables (of 65 variables analyzed), no significant group by trials interactions were found (based on a repeated measures ANOVA). The two exceptions were unrelated and inconsequential. For 27 of the 38 subjects, average urinary chromium loss at pre was 0.36 μg/24 hr, whereas it was undetectable (< 0.1 μg/24 hr) for 10 subjects and excessive in 1 subject (2.4 μg/24 hr). Subjects receiving chromium supplements demonstrated urinary chromium losses five times greater than those in the placebo group at mid and post. Chromium picolinate supplementation was ineffective in bringing about changes in body composition or strength during a program of intensive weight-lifting training.

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