scholarly journals Four Weeks of 16/8 Time Restrictive Feeding in Endurance Trained Male Runners Decreases Fat Mass, without Affecting Exercise Performance

Nutrients ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 2941
Author(s):  
Ashley P. Tovar ◽  
Christine E. Richardson ◽  
Nancy L. Keim ◽  
Marta D. Van Loan ◽  
Brian A. Davis ◽  
...  
Keyword(s):  
Fat Mass ◽  
Exercise Performance ◽  
Dietary Pattern ◽  
Dietary Intervention ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Time Trial ◽  
Fat Free Mass ◽  
Treadmill Running ◽  
Endurance Runners

Background: Time restricted Feeding (TRF) is a dietary pattern utilized by endurance athletes, but there is insufficient data regarding its effects on performance and metabolism in this population. The purpose of this investigation was to examine the effects of a 16/8 TRF dietary pattern on exercise performance in trained male endurance runners. Methods: A 4-week randomized crossover intervention was used to compare an 8-h TRF to a 12-h normal diet (ND) feeding window. Exercise training and dietary intake were similar across interventions. Runners completed a dual-energy X-ray absorptiometry (DXA) scan to assess body composition, a graded treadmill running test to assess substrate utilization, and ran a 10 km time trial to assess performance. Results: There was a significant decrease in fat mass in the TRF intervention (−0.8 ± 1.3 kg with TRF (p = 0.05), vs. +0.1 ± 4.3 kg with ND), with no significant change in fat-free mass. Exercise carbon dioxide production (VCO2) and blood lactate concentration were significantly lower with the TRF intervention (p ≤ 0.02). No significant changes were seen in exercise respiratory exchange ratio or 10 km time trial performance (−00:20 ± 3:34 min:s TRF vs. −00:36 ± 2:57 min:s ND). Conclusion: This investigation demonstrated that adherence to a 4-week 16/8 TRF dietary intervention decreased fat mass and maintained fat-free mass, while not affecting running performance, in trained male endurance runners.

Effect of graded erythrocythemia on cardiovascular and metabolic responses to exercise

1986 ◽  
Vol 61 (5) ◽  
pp. 1942-1948 ◽  
Author(s):  
L. L. Spriet ◽  
N. Gledhill ◽  
A. B. Froese ◽  
D. L. Wilkes
Keyword(s):  
Cardiovascular Response ◽  
Autologous Blood ◽  
Lactate Concentration ◽  
Treadmill Running ◽  
Metabolic Responses ◽  
Arterial Blood ◽  
Peak Lactate ◽  
Blood Pressures ◽  
Acid Base Status ◽  
Endurance Runners

The effects of graded induced erythrocythemia on cardiovascular and metabolic responses to intense treadmill running were studied in four highly trained endurance runners. Three autologous infusions of 1 unit (U) whole blood (450 ml/U) were administered sequentially 2–7 days apart. Maximal O2 consumption (VO2max) increased from 5.04 l/min at control (C) to 5.24 l/min after 2 U (R2) and 5.38 l/min after 3 U (R3). Cardiac output during treadmill running at 91% control VO2max was 28.2 l/min at C, 29.8 l/min at R2, and 33.1 l/min at R3. Corresponding heart rates were unchanged, and stroke volume was increased at R3. Peak lactate concentration was reduced, and arterial acid-base status improved at R2 and R3 after standardized bouts of intense exercise. Arterial blood pressures and electrocardiograms during exercise were not affected by erythrocythemia. We conclude that the reinfusion of up to 3 U of autologous blood into highly trained endurance runners who have normal hematology does not adversely affect their cardiovascular response to maximal exercise. In addition, the increases in VO2max following reinfusion of 2 U, and again after 3 U, suggest that the aerobic power of the working muscles was not surpassed at these levels of erythrocythemia.

scholarly journals Does caffeine supplementation alter energy contribution during a work-based ~30 min cycling time-trial?

2020 ◽  
Vol 34 (3) ◽  
pp. 471-481
Author(s):  
Gabriel Barreto ◽  
Rafael Pires da Silva ◽  
Guilherme Yamaguchi ◽  
Luana Farias de Oliveira ◽  
Vitor de Salles Painelli ◽  
...  
Keyword(s):  
Perceived Exertion ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Time Trial ◽  
Energy System ◽  
Energy Contribution ◽  
Mean Power ◽  
Double Blind ◽  
Cycling Time Trial ◽  
Cycling Time

Caffeine has been shown to increase anaerobic energy contribution during short-duration cycling time-trials (TT) though no information exists on whether caffeine alters energy contribution during more prolonged, aerobic type TTs. The aim of this study was to determine the effects of caffeine supplementation on longer and predominantly aerobic exercise. Fifteen recreationally-trained male cyclists (age 38±8 y, height 1.76±0.07 m, body mass 72.9±7.7 kg) performed a ~30 min cycling TT following either 6 mg·kg-1BM caffeine (CAF) or placebo (PLA) supplementation, and one control (CON) session without supplementation, in a double- -blind, randomised, counterbalance and cross-over design. Mean power output (MPO) was recorded as the outcome measure. Respiratory values were measured throughout exercise for the determination of energy system contribution. Data were analysed using mixed-models. CAF improved mean MPO compared to CON (P=0.01), and a trend towards an improvement compared to PLA (P=0.07); there was no difference in MPO at any timepoint throughout the exercise between conditions. There was a main effect of Condition (P=0.04) and Time (P<0.0001) on blood lactate concentration, which tended to be higher in CAF vs. both PLA and CON (Condition effect, both P=0.07). Ratings of perceived exertion increased over time (P<0.0001), with no effect of Condition or interaction (both P>0.05). Glycolytic energy contribution was increased in CAF compared to CON and PLA (both P<0.05), but not aerobic or ATP-CP (both P>0.05). CAF improved aerobic TT performance compared to CON, which could be explained by increased glycolytic energy contribution.

Magnesium homeostasis during high-intensity anaerobic exercise in men

1987 ◽  
Vol 62 (2) ◽  
pp. 545-550 ◽  
Author(s):  
P. A. Deuster ◽  
E. Dolev ◽  
S. B. Kyle ◽  
R. A. Anderson ◽  
E. B. Schoomaker
Keyword(s):  
High Intensity ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Anaerobic Exercise ◽  
Treadmill Running ◽  
Standard Diet ◽  
Base Line ◽  
Peripheral Blood Mononuclear ◽  
Exercise Induced ◽  
Mg Content

This study was conducted to determine whether short-term, high-intensity anaerobic exercise alters Mg homeostasis. Thirteen men performed intermittent bouts of treadmill running at 90% of their predetermined maximum O2 uptake until exhaustion on one occasion during a week in which all men were consuming a standard diet (115 mg Mg/1,000 kcal). Plasma and erythrocyte Mg concentrations and peripheral blood mononuclear cell Mg content were measured before and after the exercise. Complete 24-h urine collections were obtained on control days, on the day of exercise, and on the day after exercise. Exercise induced a transient but significant decrease in plasma Mg content (-6.8%; P less than 0.01); over 85% of the loss could be accounted for by a shift to the erythrocytes. Significant increases in urinary excretion of Mg were observed on the day of exercise (131.5 +/- 6.8 mg/day) compared with control days (108 +/- 6.6 mg/day), with the percent increase correlating with postexercise blood lactate concentration (r = 0.68; P less than 0.01) and oxygen consumption during recovery (r = 0.84; P less than 0.001). The data indicate that high-intensity anaerobic exercise induces intercompartmental Mg shifts in blood that return to preexercise values within 2 h and urinary losses on the day of exercise that return to base line the day after exercise. It is postulated that the exercise-induced increase in Mg excretion may depend on the intensity of the exercise, and the relative contribution of anaerobic metabolism to the total energy expended during exercise.

Influence of Caffeine and Sodium Citrate Ingestion on 1,500-m Exercise Performance in Elite Wheelchair Athletes: A Pilot Study

2014 ◽  
Vol 24 (3) ◽  
pp. 296-304 ◽  
Author(s):  
Joelle Leonie Flueck ◽  
Samuel Mettler ◽  
Claudio Perret
Keyword(s):  
Exercise Performance ◽  
Sodium Citrate ◽  
Lactate Concentration ◽  
Time Trial ◽  
Sodium Concentration ◽  
Ergogenic Effect ◽  
Double Blind Study ◽  
Double Blind ◽  
Wheelchair Athletes ◽  
National Team

The aim of this study was to investigate whether caffeine and/or sodium citrate have an ergogenic effect on the 1,500-m exercise performance in elite wheelchair athletes. A placebo-controlled, randomized, cross-over and double-blind study design was conducted with the four treatments placebo, caffeine, sodium citrate and the combination of caffeine and sodium citrate. Nine healthy, elite wheelchair-racing athletes (median: [min; max] age: 28 y [23; 54]; height: 173 cm [165; 188]; weight: 62.9 kg [48.9; 68.4], category T53/54) completed the study. All athletes were national team members, including several Paralympic Games, World and European Championship medalists. The athletes performed a 1,500-m time trial four times on a wheelchair training roller. Time to complete 1,500-m, pH, bicarbonate and sodium concentration as well as lactate concentration were measured. The time to complete 1,500-m was not significantly different between the four treatments (placebo: 170.6 s [141.7; 232.0]; caffeine: 179.5 s [134.8; 239.6]; sodium citrate: 178.3 s [136.4; 247.1]; combination: 177.6 s [136.1; 256.2]). However, pH and bicarbonate concentrations were significantly increased with sodium citrate ingestion compared with placebo. Moreover, maximal lactate concentrations were significantly higher in the caffeine and the combination treatment compared with placebo. The supplementation with sodium citrate and/or caffeine did not provide an ergogenic effect on the 1,500-m exercise performance in wheelchair elite athletes.

Influence of acetaminophen on performance during time trial cycling

2010 ◽  
Vol 108 (1) ◽  
pp. 98-104 ◽  
Author(s):  
Alexis R. Mauger ◽  
Andrew M. Jones ◽  
Craig A. Williams
Keyword(s):  
Perceived Exertion ◽  
Pain Perception ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Time Trial ◽  
Pain Tolerance ◽  
Rating Of Perceived Exertion ◽  
Significant Difference ◽  
Perceived Pain ◽  
Condition B

To establish whether acetaminophen improves performance of self-paced exercise through the reduction of perceived pain, 13 trained male cyclists performed a self-paced 10-mile (16.1 km) cycle time trial (TT) following the ingestion of either acetaminophen (ACT) or a placebo (PLA), administered in randomized double-blind design. TT were completed in a significantly faster time ( t12 = 2.55, P < 0.05) under the ACT condition (26 min 15 s ± 1 min 36 s vs. 26 min 45 s ± 2 min 2 s). Power output (PO) was higher during the middle section of the TT in the ACT condition, resulting in a higher mean PO ( P < 0.05) (265 ± 12 vs. 255 ± 15 W). Blood lactate concentration (B[La]) and heart rate (HR) were higher in the ACT condition (B[La] = 6.1 ± 2.9 mmol/l; HR = 87 ± 7%max) than in the PLA condition (B[La] = 5.1 ± 2.6 mmol/l; HR = 84 ± 9%max) ( P < 0.05). No significant difference in rating of perceived exertion (ACT = 15.5 ± 0.2; PLA = 15.7 ± 0.2) or perceived pain (ACT = 5.6 ± 0.2; PLA = 5.5 ± 0.2) ( P > 0.05) was observed. Using acetaminophen, participants cycled at a higher mean PO, with an increased HR and B[La], but without changes in perceived pain or exertion. Consequently, completion time was significantly faster. These findings support the notion that exercise is regulated by pain perception, and increased pain tolerance can improve exercise capacity.

A Comparison of Different Prerace Warm-Up Strategies on 1-km Cycling Time-Trial Performance

2020 ◽  
Vol 15 (8) ◽  
pp. 1109-1116
Author(s):  
Mathias T. Vangsoe ◽  
Jonas K. Nielsen ◽  
Carl D. Paton
Keyword(s):  
Blood Lactate ◽  
Power Output ◽  
Peak Power ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Time Trial ◽  
Peak Power Output ◽  
Warm Up ◽  
Performance Time ◽  
Competitive Cyclists

Purpose: Ischemic preconditioning (IPC) and postactivation potentiation (PAP) are warm-up strategies proposed to improve high-intensity sporting performance. However, only few studies have investigated the benefits of these strategies compared with an appropriate control (CON) or an athlete-selected (SELF) warm-up protocol. Therefore, this study examined the effects of 4 different warm-up routines on 1-km time-trial (TT) performance with competitive cyclists. Methods: In a randomized crossover study, 12 well-trained cyclists (age 32 [10] y, mass 77.7 [4.6] kg, peak power output 1141 [61] W) performed 4 different warm-up strategies—(CON) 17 minutes CON only, (SELF) a self-determined warm-up, (IPC) IPC + CON, or (PAP) CON + PAP—prior to completing a maximal-effort 1-km TT. Performance time and power, quadriceps electromyograms, muscle oxygen saturation (SmO2), and blood lactate were measured to determine differences between trials. Results: There were no significant differences (P > .05) in 1-km performance time between CON (76.9 [5.2] s), SELF (77.3 [6.0] s), IPC (77.0 [5.5] s), or PAP (77.3 [5.9] s) protocols. Furthermore, there were no significant differences in mean or peak power output between trials. Finally, electromyogram activity, SmO2, and recovery blood lactate concentration were not different between conditions. Conclusions: Adding IPC or PAP protocols to a short CON warm-up appears to provide no additional benefit to 1-km TT performance with well-trained cyclists and is therefore not recommended. Furthermore, additional IPC and PAP protocols had no effect on electromyograms and SmO2 values during the TT or peak lactate concentration during recovery.

Effect of endurance training on oxygen uptake kinetics during treadmill running

2000 ◽  
Vol 89 (5) ◽  
pp. 1744-1752 ◽  
Author(s):  
Helen Carter ◽  
Andrew M. Jones ◽  
Thomas J. Barstow ◽  
Mark Burnley ◽  
Craig Williams ◽  
...  
Keyword(s):  
Oxygen Uptake ◽  
Training Program ◽  
Endurance Training ◽  
Slow Component ◽  
Minute Ventilation ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Treadmill Running ◽  
Endurance Running ◽  
Running Training

The purpose of this study was to examine the effect of endurance training on oxygen uptake (V˙o 2) kinetics during moderate [below the lactate threshold (LT)] and heavy (above LT) treadmill running. Twenty-three healthy physical education students undertook 6 wk of endurance training that involved continuous and interval running training 3–5 days per week for 20–30 min per session. Before and after the training program, the subjects performed an incremental treadmill test to exhaustion for determination of the LT and the V˙o 2 max and a series of 6-min square-wave transitions from rest to running speeds calculated to require 80% of the LT and 50% of the difference between LT and maximal V˙o 2. The training program caused small (3–4%) but significant increases in LT and maximalV˙o 2 ( P < 0.05). TheV˙o 2 kinetics for moderate exercise were not significantly affected by training. For heavy exercise, the time constant and amplitude of the fast component were not significantly affected by training, but the amplitude of theV˙o 2 slow component was significantly reduced from 321 ± 32 to 217 ± 23 ml/min ( P< 0.05). The reduction in the slow component was not significantly correlated to the reduction in blood lactate concentration ( r = 0.39). Although the reduction in the slow component was significantly related to the reduction in minute ventilation ( r = 0.46; P < 0.05), it was calculated that only 9–14% of the slow component could be attributed to the change in minute ventilation. We conclude that theV˙o 2 slow component during treadmill running can be attenuated with a short-term program of endurance running training.

Cardiopulmonary adaptations to pneumonectomy in dogs. I. Maximal exercise performance

1992 ◽  
Vol 73 (1) ◽  
pp. 362-367 ◽  
Author(s):  
C. C. Hsia ◽  
L. F. Herazo ◽  
R. L. Johnson
Keyword(s):  
Stroke Volume ◽  
Exercise Performance ◽  
Sham Group ◽  
Maximal Exercise ◽  
Lactate Concentration ◽  
Left Lung ◽  
Blood Lactate Concentration ◽  
O2 Uptake ◽  
Group A ◽  
Exercise Induced

Maximal exercise performance was evaluated in four adult foxhounds after right pneumonectomy (removal of 58% of lung) and compared with that in seven sham-operated control dogs 6 mo after surgery. Maximal O2 uptake (ml O2.min-1.kg-1) was 142.9 +/- 1.9 in the sham group and 123.0 +/- 3.8 in the pneumonectomy group, a reduction of 14% (P less than 0.001). Maximal stroke volume (ml/kg) was 2.59 +/- 0.10 in the sham group and 1.99 +/- 0.05 in the pneumonectomy group, a reduction of 23% (P less than 0.005). Lung diffusing capacity (DL(CO)) (ml.min-1.Torr-1.kg-1) reached 2.27 +/- 0.08 in the combined lungs of the sham group and 1.67 +/- 0.07 in the remaining lung of the pneumonectomy group (P less than 0.001). In the pneumonectomy group, DL(CO) of the left lung was 76% greater than that in the left lung of controls. Blood lactate concentration and hematocrit were significantly higher at exercise in the pneumonectomy group. We conclude that, in dogs after resection of 58% of lung, O2 uptake, cardiac output, stroke volume, and DL(CO) at maximal exercise were restricted. However, the magnitude of overall impairment was surprisingly small, indicating a remarkable ability to compensate for the loss of one lung. This compensation was achieved through the recruitment of reserves in DL(CO) in the remaining lung, the development of exercise-induced polycythemia, and the maintenance of a relatively large stroke volume in the face of an increased pulmonary vascular resistance.

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