Physiological Determinants of Time to Exhaustion during Intermittent Treadmill Running at vV·O2max

The study analyzed the effect of an açai (Euterpe oleracea Mart.) functional beverage (AB) on muscle and oxidative stress markers, cardiorespiratory responses, perceived exertion, and time-to-exhaustion during maximal treadmill running. The beverage was developed as an ergogenic aid for athletes and contained 27.6 mg of anthocyanins per dose. Fourteen athletes performed 3 exercise tests: a ramp-incremental maximal exercise test and 2 maximal exercise bouts performed in 2 conditions (AB and without AB (control)) at 90% maximal oxygen uptake.Blood was collected at baseline and after maximal exercise in both conditions to determine biomarkers. AB increased time to exhaustion during short-term high-intensity exercise (mean difference: 69 s, 95% confidence interval = –296 s to 159 s, t = 2.2, p = 0.045), attenuating the metabolic stress induced by exercise (p < 0.05). AB also reduced perceived exertion and enhanced cardiorespiratory responses (p < 0.05). The AB may be a useful and practical ergogenic aid to enhance performance during high-intensity training.

Download Full-text

Acute administration of high doses of taurine does not substantially improve high-intensity running performance and the effect on maximal accumulated oxygen deficit is unclear

Applied Physiology Nutrition and Metabolism ◽

10.1139/apnm-2015-0435 ◽

2016 ◽

Vol 41 (5) ◽

pp. 498-503 ◽

Cited By ~ 14

Author(s):

Fabio Milioni ◽

Elvis de Souza Malta ◽

Leandro George Spinola do Amaral Rocha ◽

Camila Angélica Asahi Mesquita ◽

Ellen Cristini de Freitas ◽

...

Keyword(s):

Oxygen Uptake ◽

Exercise Intensity ◽

Maximal Oxygen Uptake ◽

High Intensity ◽

Treadmill Running ◽

Oxygen Deficit ◽

Time To Exhaustion ◽

Acute Administration ◽

Running Performance ◽

Accumulated Oxygen Deficit

The aim of the present study was to investigate the effects of acute administration of taurine overload on time to exhaustion (TTE) of high-intensity running performance and alternative maximal accumulated oxygen deficit (MAODALT). The study design was a randomized, placebo-controlled, crossover design. Seventeen healthy male volunteers (age: 25 ± 6 years; maximal oxygen uptake: 50.5 ± 7.6 mL·kg−1·min−1) performed an incremental treadmill-running test until voluntary exhaustion to determine maximal oxygen uptake and exercise intensity at maximal oxygen uptake. Subsequently, participants completed randomly 2 bouts of supramaximal treadmill-running at 110% exercise intensity at maximal oxygen uptake until exhaustion (placebo (6 g dextrose) or taurine (6 g) supplementation), separated by 1 week. MAODALT was determined using a single supramaximal effort by summating the contribution of the phosphagen and glycolytic pathways. When comparing the results of the supramaximal trials (i.e., placebo and taurine conditions) no differences were observed for high-intensity running TTE (237.70 ± 66.00 and 277.30 ± 40.64 s; p = 0.44) and MAODALT (55.77 ± 8.22 and 55.06 ± 7.89 mL·kg−1; p = 0.61), which seem to indicate trivial and unclear differences using the magnitude-based inferences approach, respectively. In conclusion, acute 6 g taurine supplementation before exercise did not substantially improve high-intensity running performance and showed an unclear effect on MAODALT.

Download Full-text

Skeletal muscle cytochrome c and myoglobin, endurance, and frequency of training

Journal of Applied Physiology ◽

10.1152/jappl.1981.51.3.746 ◽

1981 ◽

Vol 51 (3) ◽

pp. 746-749 ◽

Cited By ~ 52

Author(s):

R. C. Hickson

Keyword(s):

Skeletal Muscle ◽

Cytochrome C ◽

Vastus Lateralis ◽

Training Group ◽

Treadmill Running ◽

Female Rats ◽

Time To Exhaustion ◽

Training Frequency ◽

Muscle Types ◽

Fast Twitch

This study was undertaken to evaluate the effects of various training frequencies on performance capacity, the mitochondrial marker cytochrome c, and myoglobin, which is responsible for storage and transport of O2, in the three types of skeletal muscle. Female rats were trained by treadmill running up to 120 min/day, either 2, 4, or 6 days/wk for 14 wk. As a result of training, exercise time to exhaustion was increased in proportion to the number of training sessions per week. Cytochrome c concentration increased (range 20–90%) as a linear function of the number of exercises per week in the fast-twitch red vastus lateralis (FTR), the slow-twitch soleus (STR), and the mixed plantaris muscles. However, the concentration of cytochrome c in fast-twitch white vastus lateralis (FTW) muscles increased to approximately the same extent (40–50%) in all training groups. The increases in myoglobin concentration (13–45%) with training were significantly related to frequency in FTR muscle but not in STR muscle. Myoglobin levels in FTW muscle remained unchanged, regardless of training group. These results provide evidence that the capacity to perform endurance exercise and the mitochondrial content of the red skeletal muscle types are directly affected by training frequency.

Download Full-text

DL-3-n-butylphthalide improved physical and learning and memory performance of rodents exposed to acute and chronic hypobaric hypoxia

Military Medical Research ◽

10.1186/s40779-021-00314-7 ◽

2021 ◽

Vol 8 (1) ◽

Author(s):

Gang Xu ◽

Yi-Kun Shi ◽

Bin-Da Sun ◽

Lu Liu ◽

Guo-Ji E. ◽

...

Keyword(s):

Learning And Memory ◽

Hypobaric Hypoxia ◽

Gastrocnemius Muscle ◽

Chronic Hypoxia ◽

Acute Hypoxia ◽

Treadmill Running ◽

Hypoxia Tolerance ◽

Control Group ◽

Time To Exhaustion ◽

Atp Levels

Abstract Background Studies have revealed the protective effect of DL-3-n-butylphthalide (NBP) against diseases associated with ischemic hypoxia. However, the role of NBP in animals with hypobaric hypoxia has not been elucidated. This study investigated the effects of NBP on rodents with acute and chronic hypobaric hypoxia. Methods Sprague-Dwaley rats and Kunming mice administered with NBP (0, 60, 120, and 240 mg/kg for rats and 0, 90, 180, and 360 mg/kg for mice) were placed in a hypobaric hypoxia chamber at 10,000 m and the survival percentages at 30 min were determined. Then, the time and distance to exhaustion of drug-treated rodents were evaluated during treadmill running and motor-driven wheel-track treadmill experiments, conducted at 5800 m for 3 days or 20 days, to evaluate changes in physical functions. The frequency of active escapes and duration of active escapes were also determined for rats in a shuttle-box experiment, conducted at 5800 m for 6 days or 27 days, to evaluate changes in learning and memory function. ATP levels were measured in the gastrocnemius muscle and malonaldehyde (MDA), superoxide dismutase (SOD), hydrogen peroxide (H2O2), glutathione peroxidase (GSH-Px), and lactate were detected in sera of rats, and routine blood tests were also performed. Results Survival analysis at 10,000 m indicated NBP could improve hypoxia tolerance ability. The time and distance to exhaustion for mice (NBP, 90 mg/kg) and time to exhaustion for rats (NBP, 120 and 240 mg/kg) significantly increased under conditions of acute hypoxia compared with control group. NBP treatment also significantly increased the time to exhaustion for rats when exposed to chronic hypoxia. Moreover, 240 mg/kg NBP significantly increased the frequency of active escapes under conditions of acute hypoxia. Furthermore, the levels of MDA and H2O2 decreased but those of SOD and GSH-Px in the sera of rats increased under conditions of acute and chronic hypoxia. Additionally, ATP levels in the gastrocnemius muscle significantly increased, while lactate levels in sera significantly decreased. Conclusion NBP improved physical and learning and memory functions in rodents exposed to acute or chronic hypobaric hypoxia by increasing their anti-oxidative capacity and energy supply.

Download Full-text

Does Emotion Regulation Predict Gains in Exercise-Induced Fitness? A Prospective Mixed-Effects Study with Elite Helicopter Pilots

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17114174 ◽

2020 ◽

Vol 17 (11) ◽

pp. 4174

Author(s):

David Cárdenas ◽

Iker Madinabeitia ◽

Francisco Alarcón ◽

José C. Perales

Keyword(s):

Emotion Regulation ◽

Strong Predictor ◽

Treadmill Running ◽

Time To Exhaustion ◽

Negative Urgency ◽

Expressive Suppression ◽

Helicopter Pilots ◽

Before And After ◽

Fitness Training ◽

Exercise Induced

Emotion regulation (ER) is a strong predictor of different aspects of mental health and wellbeing. However, only recently has ER been examined in relation to physical activity and its effects on fitness. In the present study, 26 elite helicopter pilots, serving in the Spanish Air Force, were physically trained for 6 months, and their level of fitness (maximum oxygen consumption and time to exhaustion in a treadmill-running test) was assessed before and after that period. Additionally, two indices of emotion regulation (general adaptiveness of ER strategies, as measured by the Emotion Regulation Questionnaire (ERQ), and negative urgency, as measured by the UPPS-P questionnaire) measured at baseline were used as prospective predictors of fitness improvement. After controlling for individual features, baseline fitness, and type of training, better emotion regulation strategies (more cognitive reappraisal plus less expressive suppression) predicted larger fitness gains (p = 0.028). Incidental emotion regulation, as measured by the negative urgency index, failed to predict pre–post-fitness changes (p = 0.734). These results suggest that fostering emotion regulation skills may improve the effectiveness of fitness training programs.

Download Full-text

The Accuracy of the Critical Velocity Test for Predicting Time to Exhaustion during Treadmill Running

International Journal of Sports Medicine ◽

10.1055/s-2007-1021242 ◽

1992 ◽

Vol 13 (02) ◽

pp. 121-124 ◽

Cited By ~ 50

Author(s):

M. Pepper ◽

T. Housh ◽

G. Johnson

Keyword(s):

Critical Velocity ◽

Treadmill Running ◽

Time To Exhaustion

Download Full-text

Reliability of Time to Exhaustion Treadmill Running as a Measure of Human Endurance Capacity

International Journal of Sports Medicine ◽

10.1055/s-0035-1555928 ◽

2015 ◽

Vol 37 (03) ◽

pp. 219-223 ◽

Cited By ~ 2

Author(s):

A. Alghannam ◽

D. Jedrzejewski ◽

M. Tweddle ◽

H. Gribble ◽

J. Bilzon ◽

...

Keyword(s):

Treadmill Running ◽

Time To Exhaustion ◽

Endurance Capacity

Download Full-text

Metabolic, hormonal and performance effects of isomaltulose ingestion before prolonged aerobic exercise: a double-blind, randomised, cross-over trial

Journal of the International Society of Sports Nutrition ◽

10.1186/s12970-021-00439-z ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Hannah L. Notbohm ◽

Joshua F. Feuerbacher ◽

Finn Papendorf ◽

Nils Friese ◽

Mats W. Jacobs ◽

...

Keyword(s):

Blood Glucose ◽

Constant Load ◽

Carbohydrate Oxidation ◽

Treadmill Running ◽

Time To Exhaustion ◽

Blood Samples ◽

Running Performance ◽

Oxidation Rates ◽

Lower Baseline ◽

Gastrointestinal Discomfort

Abstract Background Isomaltulose has been discussed as a low glycaemic carbohydrate but evidence concerning performance benefits and physiological responses has produced varying results. Therefore, we primarily aimed to investigate the effects of isomaltulose ingestion compared to glucose and maltodextrin on fat and carbohydrate oxidation rates, blood glucose levels and serum hormone concentrations of insulin and glucose-dependent insulinotropic polypeptide (GIP). As secondary aims, we assessed running performance and gastrointestinal discomfort. Methods Twenty-one male recreational endurance runners performed a 70-min constant load trial at 70% maximal running speed (Vmax), followed by a time to exhaustion (TTE) test at 85% Vmax after ingesting either 50 g isomaltulose, maltodextrin or glucose. Fat and carbohydrate oxidation rates were calculated from spiroergometric data. Venous blood samples for measurement of GIP and insulin were drawn before, after the constant load trial and after the TTE. Capillary blood samples for glucose concentrations and subjective feeling of gastrointestinal discomfort were collected every 10 min during the constant load trial. Results No between-condition differences were observed in the area under the curve analysis of fat (p = 0.576) and carbohydrate oxidation rates (p = 0.887). Isomaltulose ingestion led to lower baseline postprandial concentrations of blood glucose compared to maltodextrin (percent change [95% confidence interval], − 16.7% [− 21.8,-11.6], p < 0.001) and glucose (− 11.5% [− 17.3,-5.7], p = 0.001). Similarly, insulin and GIP concentrations were also lower following isomaltulose ingestion compared to maltodextrin (− 40.3% [− 50.5,-30.0], p = 0.001 and − 69.1% [− 74.3,-63.8], p < 0.001, respectively) and glucose (− 32.6% [− 43.9,-21.2], p = 0.012 and − 55.8% [− 70.7,-40.9], p < 0.001, respectively). Furthermore, glucose fluctuation was lower after isomaltulose ingestion compared to maltodextrin (− 26.0% [− 34.2,-17.8], p < 0.001) and glucose (− 17.4% [− 29.1,-5.6], p < 0.001). However, during and after exercise, no between-condition differences for glucose (p = 0.872), insulin (p = 0.503) and GIP (p = 0.244) were observed. No between-condition differences were found for TTE (p = 0.876) or gastrointestinal discomfort (p = 0.119). Conclusion Isomaltulose ingestion led to lower baseline postprandial concentrations of glucose, insulin and GIP compared to maltodextrin and glucose. Consequently, blood glucose fluctuations were lower during treadmill running after isomaltulose ingestion, while no between-condition differences were observed for CHO and fat oxidation rates, treadmill running performance and gastrointestinal discomfort. Further research is required to provide specific guidelines on supplementing isomaltulose in performance and health settings.

Download Full-text

Morning Preconditioning Exercise Does Not Increase Afternoon Performance in Competitive Runners

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2020-0747 ◽

2021 ◽

pp. 1-8

Author(s):

Even Brøndbo Dahl ◽

Eivind Øygard ◽

Gøran Paulsen ◽

Bjarne Rud ◽

Thomas Losnegard

Keyword(s):

Low Frequency ◽

Running Economy ◽

Treadmill Running ◽

Time To Exhaustion ◽

Maximum Oxygen Consumption ◽

Improve Performance ◽

Low Intensity ◽

Force Ratio ◽

Evoked Force ◽

Low Frequency Fatigue

Purpose: Preconditioning exercise is a widely used strategy believed to enhance performance later the same day. The authors examined the influence of preconditioning exercises 6 hours prior to a time-to-exhaustion (TTE) test during treadmill running. Methods: Ten male competitive runners (age = 26 [3] y, height = 184 [8] cm, weight = 73 [9] kg, maximum oxygen consumption = 72 [7] mL·kg−1·min−1) did a preconditioning session of running (RUN) or resistance exercise (RES) or no morning exercise (NoEx) in a randomized order, separated by >72 hours. The RUN consisted of 15 minutes of low-intensity running and 4 × 15 seconds at race pace (21–24 km·h−1) on a treadmill; RES involved 5 minutes of low-intensity running and 2 × 3 repetitions of isokinetic 1-leg shallow squats with maximal mobilization. Following a 6-hour break, electrically evoked force (m. vastus medialis), countermovement jump, running economy, and a TTE of approximately 2 minutes were examined. Results: Relative to NoEx, no difference was seen for RUN or RES in TTE (mean ± 95% CI: −1.3% ± 3.4% and −0.5% ± 6.0%) or running economy (0.2% ± 1.6% and 1.9% ± 2.7%; all Ps > .05). Jump height was not different for the RUN condition (1.0% ± 2.7%]) but tended to be higher in RES than in the NoEx condition (1.5% ± 1.6%, P = .07). The electrically evoked force tended to reveal low-frequency fatigue (reduced 20:50-Hz peak force ratio) only after RES compared to NoEx (−4.5% ± 4.6%, P = .06). Conclusion: The RUN or RES 6 hours prior to approximately 2 minutes of TTE running test did not improve performance in competitive runners.

Download Full-text

Influence of Post-Exercise Carbohydrate-Protein Ingestion on Muscle Glycogen Metabolism in Recovery and Subsequent Running Exercise

International Journal of Sport Nutrition and Exercise Metabolism ◽

10.1123/ijsnem.2016-0021 ◽

2016 ◽

Vol 26 (6) ◽

pp. 572-580 ◽

Cited By ~ 3

Author(s):

Abdullah F. Alghannam ◽

Dawid Jedrzejewski ◽

James Bilzon ◽

Dylan Thompson ◽

Kostas Tsintzas ◽

...

Keyword(s):

Muscle Glycogen ◽

Glycogen Metabolism ◽

Dry Mass ◽

Treadmill Running ◽

Time To Exhaustion ◽

Short Term ◽

Double Blind ◽

Protein Ingestion ◽

Double Blind Design ◽

Muscle Biopsies

We examined whether carbohydrate-protein ingestion influences muscle glycogen metabolism during short-term recovery from exhaustive treadmill running and subsequent exercise. Six endurance-trained individuals underwent two trials in a randomized double-blind design, each involving an initial run-to-exhaustion at 70% VO2max (Run-1) followed by 4-h recovery (REC) and subsequent run-to-exhaustion at 70% VO2max (Run-2). Carbohydrate-protein (CHO-P; 0.8 g carbohydrate·kg body mass [BM-1]·h-1 plus 0.4 g protein·kg BM-1·h-1) or isocaloric carbohydrate (CHO; 1.2 g carbohydrate·kg BM-1·h-1) beverages were ingested at 30-min intervals during recovery. Muscle biopsies were taken upon cessation of Run-1, postrecovery and fatigue in Run-2. Time-to-exhaustion in Run-1 was similar with CHO and CHO-P (81 ± 17 and 84 ± 19 min, respectively). Muscle glycogen concentrations were similar between treatments after Run-1 (99 ± 3 mmol·kg dry mass [dm-1]). During REC, muscle glycogen concentrations increased to 252 ± 45 mmol·kg dm-1 in CHO and 266 ± 30 mmol·kg dm-1 in CHO-P (p = .44). Muscle glycogen degradation during Run-2 was similar between trials (3.3 ± 1.4 versus 3.5 ± 1.9 mmol·kg dm-1·min-1 in CHO and CHO-P, respectively) and no differences were observed at the respective points of exhaustion (93 ± 21 versus 100 ± 11 mmol·kg dm-1; CHO and CHO-P, respectively). Similarly, time-to-exhaustion was not different between treatments in Run-2 (51 ± 13 and 49 ± 15 min in CHO and CHO-P, respectively). Carbohydrate-protein ingestion equally accelerates muscle glycogen resynthesis during short-term recovery from exhaustive running as when 1.2 g carbohydrate·kg BM-1·h-1 are ingested. The addition of protein did not alter muscle glycogen utilization or time to fatigue during repeated exhaustive running.

Download Full-text