High doses of sodium nitrate prior to exhaustive exercise increases plasma peroxynitrite levels in well-trained subjects: randomized, double-blinded, crossover study

2019 ◽  
Vol 44 (12) ◽  
pp. 1305-1310 ◽  
Author(s):  
Farhad Gholami ◽  
Leila Rahmani ◽  
Fatemeh Amirnezhad ◽  
Khadijeh Cheraghi
Keyword(s):  
Oxygen Consumption ◽  
Crossover Study ◽  
Sodium Nitrate ◽  
Repeated Measures ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Time To Exhaustion ◽  
High Dose ◽  
Significance Level ◽  
Double Blinded

The aim of this study was to investigate the effect of different doses of pre-workout sodium nitrate supplementation on nitric oxide, peroxynitrite levels, and performance parameters. Ten well-trained male subjects participated in a randomized, double-blinded, crossover study. They ingested 8, 16, and 24 mmol sodium nitrate or placebo (NaCl) dissolved in water at 2.5 h before an incremental exercise test. Respiratory gases (oxygen consumption, carbon dioxide production, respiratory exchange ratio) were measured throughout the exercise trials and 3 blood samples (pre-ingestion, 2.5 h post-ingestion and postexercise) were taken to analyze nitrate/nitrite (NOx) and peroxynitrite levels. Data were analyzed using repeated-measures ANOVA at significance level of P < 0.05. NOx levels significantly increased following sodium nitrate ingestion compared with placebo (placebo: 40.86 ± 10.7 μmol/L, 8 mmol: 203.69 ± 25.1 μmol/L, 16 mmol: 289.41 ± 30.1 μmol/L, and 24 mmol: 300.95 ± 42.4 μmol/L, respectively) (P = 0.0001). However, this did not induce any significant change in oxygen consumption (P = 0.351), blood lactate concentration (P = 0.245), and time-to-exhaustion (P = 0.147). Peroxynitrite levels were similar compared with placebo when participants ingested 8 and 16 mmol of inorganic nitrate but a significant increase was observed after exercise at maximal intensity when participants were supplemented with 24 mmol (mean = 14.60 ± 1.3 μmol/L, P = 0.001). Pre-workout ingestion of high dose of sodium nitrate (24 mmol) induced peroxynitrate formation, a marker of oxidative stress. Caution must be taken regarding administration of higher doses before benefits or adverse effects are established in this population.

scholarly journals Prolonged static stretching causes acute, nonmetabolic fatigue and impairs exercise tolerance during severe-intensity cycling

2020 ◽  
Vol 45 (8) ◽  
pp. 902-910
Author(s):  
Alessandro L. Colosio ◽  
Massimo Teso ◽  
Silvia Pogliaghi
Keyword(s):  
Oxygen Consumption ◽  
Exercise Tolerance ◽  
Muscle Activation ◽  
Metabolic Response ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Time To Exhaustion ◽  
Static Stretching ◽  
Perception Of Effort ◽  
Severe Intensity

We tested the hypothesis that static stretching, an acute, nonmetabolic fatiguing intervention, reduces exercise tolerance by increasing muscle activation and affecting muscle bioenergetics during cycling in the “severe” intensity domain. Ten active men (age, 24 ± 2 years; body mass, 74 ± 11 kg; height, 176 ± 8 cm) participated in identical constant-load cycling tests of equal intensity, of which 2 tests were carried out under control conditions and 2 were done after stretching. This resulted in a 5% reduction of maximal isokinetic sprinting power output. We measured (i) oxygen consumption, (ii) electromyography, (iii) deoxyhemoglobin, (iv) blood lactate concentration; (v) time to exhaustion, and (vi) perception of effort. Finally, oxygen consumption and deoxyhemoglobin kinetics were determined. Force reduction following stretching was accompanied by augmented muscle excitation at a given workload (p = 0.025) and a significant reduction in time to exhaustion (p = 0.002). The time to peak oxygen consumption was reduced by stretching (p = 0.034), suggesting an influence of the increased muscle excitation on the oxygen consumption kinetics. Moreover, stretching was associated with a mismatch between O2 delivery and utilization during the isokinetic exercise, increased perception of effort, and blood lactate concentration; these observations are all consistent with an increased contribution of the glycolytic energy system to sustain the same absolute intensity. These results suggest a link between exercise intolerance and the decreased ability to produce force. Novelty We provided the first characterization of the effects of prolonged stretching on the metabolic response during severe cycling. Stretching reduced maximal force and augmented muscle activation, which in turn increased the metabolic response to sustain exercise.

scholarly journals The effect of low dose marine protein hydrolysates on short-term recovery after high intensity performance cycling: a double-blinded crossover study

2019 ◽  
Vol 16 (1) ◽  
Author(s):  
Ingunn Mjøs ◽  
Einar Thorsen ◽  
Trygve Hausken ◽  
Einar Lied ◽  
Roy M. Nilsen ◽  
...  
Keyword(s):  
Phase Ii ◽  
High Intensity ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Time To Exhaustion ◽  
Protein Supplement ◽  
Short Term ◽  
Nutrition Supplementation ◽  
Double Blinded ◽  
Marine Protein

Abstract Background Knowledge of the effect of marine protein hydrolysate (MPH) supplementation to promote recovery after high intensity performance training is scarce. The aim of this study was to examine the effect of MPH supplementation to whey protein (WP) and carbohydrate (CHO): (CHO-WP-MPH), on short-term recovery following high intensity performance, compared to an isoenergetic and isonitrogenous supplement of WP and CHO: (CHO-WP), in male cyclists. Methods This was a double-blinded crossover study divided into three phases. Fourteen healthy men participated. In phase I, an incremental bicycle exercise test was performed for establishment of intensities used in phase II and III. In phase II (9–16 days after phase 1), the participants performed first one high intensity performance cycling session, followed by nutrition supplementation (CHO-WP-MPH or CHO-WP) and 4 hours of recovery, before a subsequent high intensity performance cycling session. Phase III (1 week after phase II), was similar to phase II except for the nutrition supplementation, where the participants received the opposite supplementation compared to phase II. Primary outcome was difference in time to exhaustion between the cycling sessions, after nutrition supplementations containing MPH or without MPH. Secondary outcomes were differences in heart rate (HR), respiratory exchange ratio (RER), blood lactate concentration and glucose. Results The mean age of the participants was 45.6 years (range 40–58). The maximal oxygen uptake (mean ± SD) measured at baseline was 54.7 ± 4.1 ml∙min− 1∙kg− 1. There were no significant differences between the two nutrition supplementations measured by time to exhaustion at the cycling sessions (meandiff = 0.85 min, p = 0.156, 95% confidence interval (CI), − 0.37, 2.06), HR (meandiff = 0.8 beats pr.min, p = 0.331, 95% CI, − 0.9, 2.5), RER (meandiff = − 0.05, p = 0.361, 95% CI -0.07 – 0.17), blood lactate concentration (meandiff = − 0.24, p = 0.511, 95% CI, − 1.00, 0.53) and glucose (meandiff = 0.23, p = 0.094, 95% CI, − 0.05, 0.51). Conclusions A protein supplement with MPH showed no effects on short-term recovery in middle-aged healthy male cyclists compared to a protein supplement without MPH. Trial registration The study was registered 02.05.2017 at ClinicalTrials.gov (Protein Supplements to Cyclists, NCT03136133, https://clinicaltrials.gov/ct2/show/NCT03136133?cond=marine+peptides&rank=1.

scholarly journals Physiological responses and cycle characteristics during double-poling versus diagonal-stride roller-skiing in junior cross-country skiers

2021 ◽  
Author(s):  
Erik P. Andersson ◽  
Irina Hämberg ◽  
Paulo Cesar Do Nascimento Salvador ◽  
Kerry McGawley
Keyword(s):  
Oxygen Uptake ◽  
Perceived Exertion ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Peak Oxygen Uptake ◽  
Submaximal Exercise ◽  
Rating Of Perceived Exertion ◽  
Time To Exhaustion ◽  
Double Poling ◽  
Cross Country

Abstract Purpose This study aimed to compare physiological factors and cycle characteristics during cross-country (XC) roller-skiing at matched inclines and speeds using the double-poling (DP) and diagonal-stride (DS) sub-techniques in junior female and male XC skiers. Methods Twenty-three well-trained junior XC skiers (11 women, 12 men; age 18.2 ± 1.2 yr.) completed two treadmill roller-skiing tests in a randomized order using either DP or DS. The exercise protocols were identical and included a 5 min warm-up, 4 × 5 min submaximal stages, and an incremental test to exhaustion, all performed at a 5° incline. Results No significant three-way interactions were observed between sex, submaximal exercise intensity, and sub-technique. For the pooled sample, higher values were observed for DP versus DS during submaximal exercise for the mean oxygen uptake kinetics response time (33%), energy cost (18%), heart rate (HR) (9%), blood lactate concentration (5.1 versus 2.1 mmol·L−1), rating of perceived exertion (12%), and cycle rate (25%), while cycle length was lower (19%) (all P < 0.001). During the time-to-exhaustion (TTE) test, peak oxygen uptake ($$\dot{V}$$ V ˙ O2peak), peak HR, and peak oxygen pulse were 8%, 2%, and 6% lower, respectively, for DP than DS, with a 29% shorter TTE during DP (pooled data, all P < 0.001). Conclusion In well-trained junior XC skiers, DP was found to exert a greater physiological load than DS during uphill XC roller-skiing at submaximal intensities. During the TTE test, both female and male athletes were able to ski for longer and reached markedly higher $$\dot{V}$$ V ˙ O2peak values when using DS compared to DP.

The Respiration of Cancer Pagurus Under Normoxic and Hypoxic Conditions

1982 ◽  
Vol 97 (1) ◽  
pp. 273-288 ◽  
Author(s):  
S. M. BRADFORD ◽  
A. C. TAYLOR
Keyword(s):  
Oxygen Consumption ◽  
Energy Savings ◽  
Lactate Concentration ◽  
Oxygen Affinity ◽  
Cardiac Activity ◽  
Blood Lactate Concentration ◽  
Minor Role ◽  
Rhythmic Pattern ◽  
Cancer Pagurus ◽  
Wide Range

The respiration of Cancer pagurus under normoxic conditions and its respiratory responses to hypoxia are described. Respiration of quiescent crabs is characterized by a rhythmic pattern of ventilation and cardiac activity in which periods of apnoea and bradycardia of approximately 5 min duration alternate with longer periods of active ventilation and cardiac activity. The significance of this rhythmic ventilatory behaviour is discussed and evidence is presented to account for this behaviour in terms of allowing energy savings to be made during periods of inactivity. During a ventilatory pause the PO2 of the post-branchial blood falls from its normal level of 94 ± 5 torr to only 24 ± 3 torr. The blood of Cancer provides a store of oxygen which is used during pausing to maintain aerobic metabolism. Anaerobic metabolism does not appear to contribute significantly to energy production during these periods since no increase in the blood lactate concentration was recorded. Cancer haemocyanin has a high oxygen affinity (P50 = 5–10 torr) and exhibits a large, positive Bohr shift (Δ log P50/pH = −1.18). However, under normal conditions the pigment has only a minor role in supplying oxygen to the tissues, since over 91% is carried in solution. Cancer pagurus exhibits quite a high degree of respiratory independence and is able to maintain its rate of oxygen consumption approximately constant over a wide range of ambient oxygen tension, down to a PO2 of 60–80 torr, below which it declines. Similarly there was little change in heart rate during hypoxia until a PO2 of 20–40 torr was reached below which it also declined sharply. Oxygen consumption during hypoxia was maintained primarily as a result of an increase in ventilation volume and oxygen extraction. During hypoxia the PO2 of both the pre- and post-branchial blood declined and resulted in a reduction in the PO2 gradient across the respiratory surface (ΔPO2). Oxygen uptake during hypoxia was facilitated, however, by an increase in the transfer factor (TO2).

scholarly journals Effects of a 2-km Swim on Markers of Cycling Performance in Elite Age-Group Triathletes

Sports ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 82
Author(s):  
Jeffrey Rothschild ◽  
George H. Crocker
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Blood Lactate ◽  
Peak Power ◽  
Maximal Oxygen Consumption ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Cycling Performance ◽  
Age Group

The purpose of this study was to examine the effects of a 2-km swim on markers of subsequent cycling performance in well-trained, age-group triathletes. Fifteen participants (10 males, five females, 38.3 ± 8.4 years) performed two progressive cycling tests between two and ten days apart, one of which was immediately following a 2-km swim (33.7 ± 4.1 min). Cycling power at 4-mM blood lactate concentration decreased after swimming by an average of 3.8% (p = 0.03, 95% CI −7.7, 0.2%), while heart rate during submaximal cycling (220 W for males, 150 W for females) increased by an average of 4.0% (p = 0.02, 95% CI 1.7, 9.7%), compared to cycling without prior swimming. Maximal oxygen consumption decreased by an average of 4.0% (p = 0.01, 95% CI −6.5, −1.4%), and peak power decreased by an average of 4.5% (p < 0.01, 95% CI −7.3, −2.3%) after swimming, compared to cycling without prior swimming. Results from this study suggest that markers of submaximal and maximal cycling are impaired following a 2-km swim.

scholarly journals Acute Effect of Quadriceps Myofascial Tissue Rolling Using A Mechanical Self-Myofascial Release Roller-Massager on Performance and Recovery in Young Elite Speed Skaters

Sports ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 246
Author(s):  
Shaher A. I. Shalfawi ◽  
Eystein Enoksen ◽  
Håvard Myklebust
Keyword(s):  
Blood Lactate ◽  
Peak Power ◽  
Subjective Experience ◽  
Performance Test ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Repeated Measure ◽  
Time To Exhaustion ◽  
Long Term Effects ◽  
Mean Power

Objectives: The main purpose of the present study was to investigate the acute effects of myofascial tissue rolling on endurance performance and recovery using a novel designed mechanical self-induced multi-bar roller-massager. Methods: a randomized crossover, repeated measure design was used. Eight national levelled, junior and neo-senior, speed skaters underwent a 10 min myofascial quadriceps rolling pre- and fifteen minutes post- a stepwise incremental cycling-test to exhaustion followed by a Wingate performance-test. The myofascial quadriceps rolling was used in one out of two laboratory testing-days. Time to exhaustion, peak oxygen uptake (VO2peak), blood lactate concentration during 30 min of recovery, and peak- and mean- power during the consecutive Wingate test were recorded. Results: Myofascial quadriceps rolling using roller-massager resulted in higher blood lactate concentration at exhaustion and a larger blood lactate clearance after 10 min to post exhaustion test (both p < 0.05), a tendency for a positive effect on Wingate peak-power (p = 0.084; d = 0.71), whereas no marked differences were observed on VO2peak, time to exhaustion and Wingate mean-power. Conclusion: Despite indications for potential benefits of the quadriceps myofascial tissue release using the mechanical self-induced multi-bar roller-massager on blood lactate concentration and Wingate peak-power, the myofascial tissue release gave no marked performance improvements nor indications of negative effects. Future studies could examine the long-term effects of myofascial tissue release on performance and recovery. Furthermore, integrating a measure of the participants’ subjective experience pre- and post the myofascial tissue release would be of great interest.

Effects of Dietary L-Arginine Intake on Cardiorespiratory and Metabolic Adaptation in Athletes

2009 ◽  
Vol 19 (4) ◽  
pp. 355-365 ◽  
Author(s):  
Raul Bescós ◽  
Carlos Gonzalez-Haro ◽  
Pere Pujol ◽  
Franchek Drobnic ◽  
Eulalia Alonso ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Control Diet ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Physiological Parameters ◽  
Physiological Adaptation ◽  
Metabolic Adaptation ◽  
High Doses ◽  
Plasma Nitrate ◽  
Level Of Significance

To assess the effect of diet enrichment with L-arginine or supplementation at high doses on physiological adaptation during exercise, 9 athletes followed 3 different diets, each over 3 consecutive days, with a wash-out period of 4 d between training sessions: control diet (CD), 5.5 ± 0.3 g/d of L-arginine; Diet 1 (rich in L-arginine food), 9.0 ± 1.1 g/d of L-arginine; and Diet 2 (the same as CD but including an oral supplement of 15 g/d), 20.5 ± 0.3 g/d of L-arginine. Plasma nitrate levels of each participant were determined on the day after each treatment. Participants performed a submaximal treadmill test (initial speed 10–11 km/hr, work increments 1 km/hr every 4 min until 85–90% VO2max, and passive recovery periods of 2 min). Oxygen uptake and heart rate were monitored throughout the test. Blood lactate concentration ([La−]b) was determined at the end of each stage. Repeated-measures ANOVA and paired Student’s t tests were used to compare the various physiological parameters between diets. The level of significance was set at p < .05. [La−]b showed a significant effect at the 5-min time point between CD and Diet 2 (CD 3.0 ± 0.5 mM, Diet 2 2.5 ± 0.5 mM, p = .03), but this tendency was not found at higher exercise intensities. No significant differences were observed in any of the cardiorespiratory or plasma nitrate levels. In conclusion, dietary L-arginine intake on the days preceding the test does not improve physiological parameters during exercise.

The Effect of Aging on the Lactate Threshold in Untrained Men

1997 ◽  
Vol 5 (1) ◽  
pp. 39-49 ◽  
Author(s):  
K. Fiona Iredale ◽  
Myra A. Nimmo
Keyword(s):  
Oxygen Consumption ◽  
Correlation Coefficient ◽  
Blood Lactate ◽  
Lactate Threshold ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Peak Oxygen Consumption ◽  
Reserve Capacity ◽  
The Difference ◽  
Treadmill Protocol

Thirty-three men (age 26–55 years) who did not exercise regularly were exercised to exhaustion using an incremental treadmill protocol. Blood lactate concentration was measured to identify lactate threshold (LT, oxygen consumption at which blood lactate concentration begins to systematically increase). The correlation coefficient for LT (ml · kg−1 · min−1) with age was not significant, but when LT was expressed as a percentage of peak oxygen consumption (VO2 peak), the correlation was r = +.69 (p < .01). This was despite a lack of significant correlation between age and VO2 peak (r = −.33). The correlation between reserve capacity (the difference between VO2 peak and LT) and age was r = −.73 (p < .01 ), and reserve capacity decreased at a rate of 3.1 ml · kg−1 · min−1 per decade. It was concluded that the percentage of VO2 peak at which LT occurs increases progressively with age, with a resultant decrease in reserve capacity.

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