High-intensity Exercise Performance Research Articles

Effects Of Low Muscle Glycogen On High-intensity Exercise Performance: A Placebo-controlled Study

Muscle glycogen is the major fuel during high-intensity exercise (HIE) and large reductions can occur after relatively short durations; however, the relationship between low muscle glycogen and HIE performance has not been investigated in a placebo-controlled design. PURPOSE: To investigate the effects of low muscle glycogen content on repeated sprint ability (RSA), ratings of perceived exertion (RPE) during HIE and neuromuscular function using a double-blinded design. METHODS: Eighteen well-trained subjects (VO2max; 57 ± 5 mL·kg-1·min-1) performed glycogen-depleting cycling exercise consisting of three periods of 10x45 s at ~110% VO2max interspersed by 135 s of passive recovery between bouts and 15 min between periods. After the glycogen-depleting exercise subjects were randomly assigned to a low (LOW) or high (HIGH) carbohydrate dietary intake for 5 hours (n = 9 in each group). The diets consisted of fluid and small amounts of bars and was blinded to assessors and participants. At baseline, after each period and following the diet manipulation RSA (5x6 s sprints separated by 24 s of rest) was evaluated. Moreover, isometric knee-extensor function (maximal voluntary contractions, voluntary activation level and electrically induced low- (20 Hz) and high-frequency (50 Hz) force production) was assessed at baseline, after the exercise intervention and following the diet administration. At the same time points a 2-min fixed intensity (~90% VO2max) cycling protocol was performed with subsequent RPE measures. Finally, muscle biopsies and blood samples were obtained. RESULTS: The glycogen-depleting exercise followed by recovery in LOW and HIGH resulted in distinct glycogen concentrations (176 ± 99 vs. 292 ± 78 mmol·kg-1 dw, P < 0.01), but indifferent blood glucose concentrations (P > 0.05). This was accompanied by an impaired RSA only in LOW (7.8 ± 5.9% reduction relative to baseline, P < 0.05) coupled with a high rating of perceived exertion during HIE in LOW compared to HIGH (7.7 ± 1.2 vs. 5.6 ± 1.2 AU, P < 0.01). In contrast, no between-group difference was observed for any aspects of neuromuscular function (P > 0.05). CONCLUSIONS: Low muscle glycogen results in impaired RSA and increased RPE during HIE, whereas voluntary and electrically induced isometric knee-extensor force remains unaffected.

Effects Of Transdermal Sodium Bicarbonate Lotion On High-intensity Cycling Performance

Pre-exercise oral ingestion of sodium bicarbonate may lead to improved high-intensity exercise performance in trained individuals. However, this practice often causes gastrointestinal distress, which can mitigate the ergogenic benefits. An alternative method of administration involves the delivery of sodium bicarbonate through applying lotion to the surface of the skin surrounding the working muscles. However, few studies have examined the ergogenic benefits of this practice. PURPOSE: To examine the effects of pre-exercise application of a sodium bicarbonate lotion (SBL) on performance during a series of intermittent high-intensity cycling bouts compared to a placebo (PLA). METHODS: In a randomized cross-over fashion, 7 trained cyclists completed a one-hour cycling performance test on a stationary trainer using their personal road bikes on two separate occasions. This protocol consisted series of maximal 5-second (neuromuscular, NM), 5-minute (maximal aerobic, MAP), 20-minute (functional threshold, FTP), and 1-minute (anaerobic capacity, AC) efforts separated by recovery. Performance was determined by the mean power output during each effort. Thirty minutes prior, subjects applied 0.4 g/kg-bw of either SBL or PLA to the quadriceps, hamstrings, and gastrocnemius. Capillary samples were collected at 1-minute and 3-minutes following the MAP, FTP, and AC tests to measure blood lactate. Differences in power output and lactate responses between conditions were tested using Wilcoxon signed-rank tests. RESULTS: There were no differences in power output during the any of the efforts between conditions. In the SBL condition, participants had higher blood lactate concentrations one-minute following the MAP test compared to PLA (p = 0.01, mean dif. = 4.3 mmol/L). CONCLUSION: Our findings suggest that pre-exercise application of SBL did not influence performance in trained cyclists. The elevated blood lactate response to the MAP effort in SBL could indicate enhanced cellular buffering and lactate clearance. Practically, this suggests that SBL could be beneficial prior to shorter time-trials or intervals performed near maximal aerobic capacity. Once the target sample of 16 cyclists have completed the study, we can provide further insight on the ergogenic effects of SBL application in this population.

Ammonia Inhalants Enhance Psychophysiological Responses and Performance During Repeated High Intensity Exercise

ABSTRACTPurpose: Ammonia inhalants (NH3) are anecdotally used in competition by athletes for their purported stimulant effects. However, evidence on the efficacy of NH3 is conflicting, and little to no studies to date have investigated its effect on repeated exercise. The purpose of this study was to examine the effects of NH3 on psychophysiological responses and performance during repeated high-intensity exercise. Methods: In a counterbalanced crossover design, physically active females completed two repeated high-intensity sprint trials with a different treatment: Control (CON; water) or Ammonia Inhalants (NH3; 0.33 cc). For each trial, participants completed 3 × 15s Wingate anaerobic tests (WAnT) separated by 2 min of active recovery. Prior to each WAnT, participants took a single 3-s inhale of the corresponding treatment. After the succession of each WAnT, heart rate (HR) and rate of perceived exertion (RPE) were documented. Subjective feelings of alertness and “psyched up” energy were measured using a visual analog scale. Trials were separated by at least 48 hr. Results: The results indicate that over the WAnTs, mean power (p = .017) and peak power (p = .006) were significantly higher with NH3 compared to CON despite a lack of changes in fatigue index (p = .928). HR (p = .101) and RPE (p = .897) were not different with varying treatments. Perceived alertness (p = .010) and psyched-up energy (p = .002) were significantly higher with NH3 versus CON. Conclusion: These findings provide empirical support for the use of NH3 to improve repeated high-intensity exercise performance in females that may be underpinned by alterations in subjective alertness and energy.

Effects of serial and acute enteric-coated sodium bicarbonate supplementation on anaerobic performance, physiological profile, and metabolomics in healthy young men.

BackgroundPrevious studies have reported that sodium bicarbonate ingestion may enhance high-intensity exercise performance and cause severe gastrointestinal distress. However, enteric-coated sodium bicarbonate may reduce gastrointestinal symptoms of sodium bicarbonate after oral administration. This remains to be confirmed. This study aimed to verify the effects of serial and acute enteric-coated sodium bicarbonate supplementation on anaerobic performance, physiological profile, and metabolomics in healthy young men.MethodsHealthy young males (n = 12) ingested 0.2 g/kg body mass of enteric-coated sodium bicarbonate (ES) in serial enteric-coated sodium bicarbonate (SES, continuous ES supplementation for 5 days) and acute enteric-coated sodium bicarbonate (AES, acute ES supplementation before exercise) or a placebo (PL) in a randomized crossover design. After each supplement protocol, the participants completed four Wingate anaerobic tests (WAT). The first three Wingate tests (testing anaerobic capacity) were performed with a 5-min passive recovery between each. After the third Wingate test, participants were required to complete a 50-min recovery followed by a fourth WAT test (testing the recovery of anaerobic capacity after 50-min intervals). Blood lactate (BLA), heart rate (HR), and ratings of perceived exertion (RPE) were measured in all conditions during the test, as was the subjective gastrointestinal–symptoms assessment questionnaire (GSAQ). Mean power (MP) and peak power (PP) were recorded after four WATs. Urine samples were collected before the test and 50 min after the 3rd WAT.ResultsSerial enteric-coated sodium bicarbonate supplementation improved anaerobic capacity in the third bout of WATs, as observed based on an increase in mean power (SES vs. PL (613 ± 57 vs. 542 ± 64 W), P = 0.024) and peak power (SES vs. PL (1,071 ± 149 vs. 905 ± 150 W), P = 0.016). Acute ES supplementation did not affect anaerobic capacity. The occurrence of gastrointestinal symptoms after enteric-coated sodium bicarbonate supplementation was minimal and no difference compared to placebo in the current study. In particular, serial enteric-coated sodium bicarbonate supplementation had no gastrointestinal side effects before the test. The AES and SES groups had a trivial effect on blood lactate compared to the PLA group. There was no significant difference in HR and RPE among the three groups. Based on targeted metabolomics analysis, the 50 min after the third WAT, the levels of lactate (P < 0.001), L-Malic acid (P < 0.05), and oxaloacetate (P < 0.05) were significantly higher in the SES group than in the PL group. Compared with the AES group, the levels of lactate and fumarate in the SES group were significantly increased (P < 0.05).ConclusionsOur study indicates that serial enteric-coated sodium bicarbonate supplementation positively improves anaerobic performance among healthy young men. However, acute ingestion of enteric-coated sodium bicarbonate did not improve anaerobic exercise performance. Either with serial or acute supplementation doses, enteric-coated sodium bicarbonate produced fewer gastrointestinal symptoms and no difference compared to placebo, especially with no gastrointestinal side effects after serial supplementation. Serial and acute supplementation of enteric-coated sodium bicarbonate might tend to promote lactate clearance. Furthermore, serial enteric-coated sodium bicarbonate ingestion may cause changes in the metabolism of lactate, L-Malic acid, oxaloacetate, and fumarate 50 min after exercise, which presumably may promote the tricarboxylic acid cycle and lactate clearance.

The effects of inspiratory muscle fatigue on subsequent high-intensity exercise performance and muscle tissue oxygenation

The effects of inspiratory muscle fatigue on subsequent high-intensity exercise performance and muscle tissue oxygenation

The Impact of Pre-Exercise Carbohydrate Meal on the Effects of Yerba Mate Drink on Metabolism, Performance, and Antioxidant Status in Trained Male Cyclists

IntroductionThe consumption of yerba mate (YM), a source of antioxidants, in a fasted state increases fatty acid oxidation (FATox) during low–moderate-intensity exercise and improves performance in high-intensity exercise. However, the impact of a pre-exercise carbohydrate (CHO) meal on YM effects during exercise is unknown.ObjectiveWe investigated the effects of yerba mate drink (YMD) consumed in the fasted state (YMD-F) or after a CHO meal (YMD-CHO) on measurements of metabolism, performance, and blood oxidative stress markers in cycling exercise.MethodsIn a randomized, repeated-measures, crossover design, eight trained male cyclists ingested (i) YMD-CHO, (ii) YMD-F, or (iii) control-water and CHO meal (Control-CHO). The YMD (an infusion of 5 g of ultrarefined leaves in 250 mL of water) was taken for 7 days and 40 min before exercise. CHO meal (1 g/kg body mass) was consumed 60 min before exercise. The cycling protocol included a 40-min low-intensity (~ 53% V̇O2peak) constant load test (CLT); a 20-min time trial (TT); and 4 × 10-s all-out sprints. Blood samples and respiratory gases were collected before, during, and/or after tests.ResultsDuring CLT, YMD-CHO increased FATox ~ 13% vs. YMD-F (P = 0.041) and ~ 27% vs. Control-CHO (P < 0.001). During TT, YMD-CHO increased FATox ~ 160% vs. YMD-F (P < 0.001) and ~ 150% vs. Control-CHO (P < 0.001). Power output during TT improved ~ 3% (P = 0.022) in YMD-CHO vs. Control-CHO and was strongly correlated with changes in serum total antioxidant capacity (r = −0.87) and oxidative stress index (r = 0.76) at post-exercise in YMD-CHO. Performance in sprints was not affected by YMD.ConclusionCHO intake did not negate the effect of YMD on FATox or TT performance. Instead, a synergism between the two dietary strategies may be present.Clinical Trial Registration NCT04642144. November 18, 2020. Retrospectively registered.

High-Intensity Interval Exercise Performance in Judo Athletes: Physiological, Perceptual, and Pacing Responses.

This study aimed to verify the behavior of physiological, perceptual, and performance responses during a high-intensity exercise in judo athletes and to identify if this protocol is able to discriminate athletes from different levels (national vs. state). Forty-five male judo athletes participated and were divided into two groups: state (age 24.2 ± 3.7years) and national (22.1 ± 3.3years). Judo athletes performed a judo-specific protocol contained high-intensity intermittent exercise consisted of 12 sets of 20s in all-out intensity. During the protocol, the repetitions and heart rate were assessed over the sets, and at the end of the protocol, the rate of perceived exertion was measured. The results showed that the national group presented higher repetitions (29 ± 4 repetitions) during the high-intensity intermittent exercise compared with state (22 ± 2 repetitions). However, the national group showed a progressive decrease of repetitions up to the middle of the protocol, which coincided with higher values of heart rate compared with state (first and second sets). There was a decrease of repetitions from the first set (p < .001) and similar values of heart rate from the third set in the state. In conclusion, the performance (in repetitions) during the high-intensity intermittent exercise was able to discriminate athletes from different competitive levels. National athletes presented better performance, but worse pacing strategy compared with state.

Royal Jelly Plus Coenzyme Q10 Supplementation Enhances High-Intensity Interval Exercise Performance via Alterations in Cardiac Autonomic Regulation and Blood Lactate Concentration in Runners.

PurposeThis study aimed to examine whether oral royal jelly (RJ) and coenzyme Q10 (CoQ10) co-supplementation could improve high-intensity interval exercise (HIIE) performance in runners, reducing exercise-induced lactic acidosis and decreasing elevated sympathetic tone following exercise.MethodsThirty regional-level runners (age: 19 ± 1 years; height: 173 ± 2 cm; body mass: 68.9 ± 2 kg; body mass index: 23.1 ± 1 kg/m2) were randomly allocated to receive either 400 mg of RJ and 60 mg of CoQ10 (RJQ) or matching placebo (PLA) once daily for 10 days. Exercise performance expressed as time taken to complete HIIE was evaluated at baseline, and then reassessed at day 10 of intervention. HIIE protocol applied to the runners included three repetitions of 100 m distance at maximum possible speed interspersed with 45 s of recovery periods. Indices of heart rate variability and blood lactate concentration were also measured before and immediately after HIIE in each group.ResultsHIIE performance significantly improved in RJQ group (p = 0.005) compared to PLA group. Blood lactate levels and sympathetic influence on the heart were significantly lower both before and after the HIIE in athletes who received RJQ (p < 0.05) compared to PLA. Regression analysis showed that oral RJQ administration for 10 days was significantly associated with reductions in HIIE-induced increases in blood lactate concentration and enhanced cardiac parasympathetic modulation following exercise compared to PLA. Principal component analysis revealed that runners treated with RJQ are grouped by the first two principal components into a separate cluster compared to PLA. Correlation analysis demonstrated that the improvements in runners’ HIIE performance were due in significant part to RJQ-induced reduction of increment in blood lactate levels in response to exercise in combination with a more rapid shift in autonomic activity toward increased parasympathetic control early at post-exercise.ConclusionThese findings suggest that RJQ supplementation for 10 days is potentially effective for enhancing HIIE performance and alleviating adverse effects of increased intramuscular acidity and prolonged sympathetic dominance following intense exercise.

Royal jelly plus coenzyme Q10 supplementation improves high-intensity interval exercise performance via changes in plasmatic and salivary biomarkers of oxidative stress and muscle damage in swimmers: a randomized, double-blind, placebo-controlled pilot trial.

ABSTRACTBackgroundExcessive production of free radicals caused by many types of exercise results in oxidative stress, which leads to muscle damage, fatigue, and impaired performance. Supplementation with royal jelly (RJ) or coenzyme Q10 (CoQ10) has been shown to attenuate exercise-induced oxidant stress in damaged muscle and improve various aspects of exercise performance in many but not all studies. Nevertheless, the effects of treatments based on RJ plus CoQ10 supplementation, which may be potentially beneficial for reducing oxidative stress and enhancing athletic performance, remain unexplored. This study aimed to examine whether oral RJ and CoQ10 co-supplementation could improve high-intensity interval exercise (HIIE) performance in swimmers, inhibiting exercise-induced oxidative stress and muscle damage.MethodsTwenty high-level swimmers were randomly allocated to receive either 400 mg of RJ and 60 mg of CoQ10 (RJQ) or matching placebo (PLA) once daily for 10 days. Exercise performance was evaluated at baseline, and then reassessed at day 10 of intervention, using a HIIE protocol. Diene conjugates (DC), Schiff bases (SB), and creatine kinase (CK) were also measured in blood plasma and saliva before and immediately after HIIE in both groups.ResultsHIIE performance expressed as number of points according to a single assessment system developed and approved by the International Swimming Federation (FINA points) significantly improved in RJQ group (p = 0.013) compared to PLA group. Exercise-induced increase in DC, SB, and CK levels in plasma and saliva significantly diminished only in RJQ group (p < 0.05). Regression analysis showed that oral RJQ administration for 10 days was significantly associated with reductions in HIIE-induced increases in plasmatic and salivary DC, SB, and CK levels compared to PLA. Principal component analysis revealed that swimmers treated with RJQ are grouped by both plasmatic and salivary principal components (PC) into a separate cluster compared to PLA. Strong negative correlation between the number of FINA points and plasmatic and salivary PC1 values was observed in both intervention groups.ConclusionThe improvements in swimmers’ HIIE performance were due in significant part to RJQ-induced reducing in lipid peroxidation and muscle damage in response to exercise. These findings suggest that RJQ supplementation for 10 days is potentially effective for enhancing HIIE performance and alleviating oxidant stress.AbbreviationsRJ, royal jelly; CoQ10, coenzyme Q10; HIIE, high-intensity interval exercise; DC, diene conjugates; SB, Schiff bases; CK, creatine kinase; RJQ, royal jelly plus coenzyme Q10; PLA, placebo; FINA points, points according to a single assessment system developed and approved by the International Swimming Federation; ROS, reactive oxygen species; 10H2DA, 10-hydroxy-2-decenoic acid; AMPK, 5′-AMP-activated protein kinase; FoxO3, forkhead box O3; MnSOD, manganese-superoxide dismutase; CAT, catalase; E, optical densities; PCA, principal component analysis; PC, principal component; MCFAs, medium-chain fatty acids; CaMKKβ, Ca2+/calmodulin-dependent protein kinase β; TBARS, thiobarbituric acid reactive substances; MDA, malondialdehyde.

Exploring the Impact of Mental Fatigue and Emotional Suppression on the Performance of High-Intensity Endurance Exercise

This study investigated the extent to which mental fatigue and emotional suppression affected exercise endurance. Twelve participants performed cycling endurance tests at 80% of their peak power up to the point of exhaustion. Two experimental conditions (mental fatigue [MF] and emotion suppression conditions [ES]) and a control condition (CO) were administered. Participants responded to psychological measures throughout the exercise trials. Both MF and ES conditions hindered exercise performance relative to the CO, and there was no statistically significant difference between the negative effects of both MF and ES conditions. Of note, however, higher levels of subjective fatigue were reported in MF, prior to commencing the exercise test. High cognitive loads that induce MF and/or engaging in ES may reduce high intensity endurance exercise performance among young adults, but further research with greater numbers of participants is needed to replicate and extend these findings.

Effects of Trehalose Solutions at Different Concentrations on High-Intensity Intermittent Exercise Performance

Trehalose solution ingested during exercise induces gradual increases in blood glucose levels and the insulin response compared with glucose solution. Trehalose solution aids in the maintenance of performance in the later stages of prolonged exercise. The purpose of this study was to identify the lowest concentration at which the properties of trehalose could be exploited. Groups of 12 healthy men (21.3 ± 1.3 years) and 10 healthy men (21.1 ± 0.7 years) with recreational training were included in experiments 1 and 2, respectively. Both experiments followed the same protocol. After fasting for 12 h, the participants performed a 60 min constant-load exercise at 40% O2 peak using a bicycle ergometer and ingested 500 mL of a trial drink (experiment 1: water, 8% glucose, and 6 or 8% trehalose; experiment 2: 4 or 6% trehalose). They performed four sets of the Wingate test combined with a 30 min constant-load exercise at 40% O2 peak. The experiment was conducted using a randomized cross-over design; trial drink experiments were conducted over intervals of 7 to 12 days. The exercise performance was evaluated based on mean power in the Wingate test. Blood was collected from the fingertip at 12 points during each experiment to measure blood glucose levels. During the high-intensity 5 h intermittent exercise, no differences were found between the groups in exercise performance in the later stages with concentrations of 8, 6, and 4% trehalose solution. The results suggest that trehalose could be useful for making a new type of mixed carbohydrate solution. Further studies to determine the trehalose response of individual athletes during endurance exercise are needed.

Preference and tolerance for high-intensity exercise performance and enjoyment

ABSTRACT High-intensity exercise has been shown to result in physiological benefits. However, little is known about why individuals choose to initiate and continue engaging in this type of exercise. It is likely individual differences exist that explain why some maintain a high-intensity exercise regimen while others do not. Thus, the purpose of the present study was to examine the predictive role of intensity preference and tolerance traits on performance and enjoyment from a high-intensity workout. Participants (N = 34; 33 ± 8 yrs) completed the Preference for and Tolerance of the Intensity of Exercise Questionnaire, then performed a 12-minute high-intensity workout (HIW; consisting of a 5 pull-ups, 10 box jumps, & 15 wall ball throws AMRAP). Intensity preference [b(lower – upper CI); 0.475(0.169–0.782), P = 0.002], but not tolerance [0.140(−0.254–0.535), P = 0.486], explained variance in HIW performance (i.e., number of repetitions completed in the 12-min AMRAP), while neither preference nor tolerance were meaningfully associated with post-HIW enjoyment (rs < 0.27). However, performance explained meaningful variance in enjoyment [0.435(0.233–0.637.18), P < 0.001]. Thus, intensity-preference influences the number of repetition completed during a HIW, but intensity-preference and tolerance are less important for HIW enjoyment. Rather, more completed repetitions was related to greater enjoyment, and experiencing greater exercise enjoyment may lead to continued high-intensity exercise engagement.

Effect of a Sugar-Free Branched Chain Amino Acid-Containing Sports Drink on Acute High Intensity Anaerobic Performance

Purpose: BioSteel® high performance sports drink (HPSD) is an enticing alternative to carbohydrate-containing sports drinks that are often associated with side effects such as gastrointestinal discomfort or post-consumption hypoglycemia. BioSteel® HPSD is carbohydrate-free and provides bioavailability of branched-chain amino acids (BCAAs) and other necessary cofactors that aid in BCAAs digestion. Here, we investigated the efficacy of BioSteel® HPSD to improve high-intensity anaerobic exercise performance in young adults. Methods: A modified Wingate anaerobic test (mWAnT) was performed by fourteen healthy college students. Each subject underwent a total of nine trials, with each trial consisting of four bouts of cycling for 10 seconds / bout. The crossover design had each subject consume either BioSteel® HPSD, placebo, or water 30 minutes prior to the onset of exercise for three trials each, respectively. Results: Participants consuming BioSteel® HPSD had significantly improved average power output expressed as an average of all bouts and all trials. Analyzing exercise performance as a function of separate 10 second bouts revealed significantly higher power output (bouts 1 and 4) and peak power (bout 1) in the BioSteel® HPSD consuming group. Despite this increased power output, subjects consuming BioSteel® HPSD did not fatigue faster or to a greater extent, as evidenced by fatigue index. Translation of power output to distance travelled indicated a significantly increased distance traveled by the subjects who drank BioSteel® HPSD. Conclusion: Collectively, our data demonstrate that BioSteel® HPSD has a positive effect on acute anaerobic performance.

Anaerobic performance after 3-day consecutive CO2-rich cold-water immersion in physically active males

Background/ObjectivesWe investigated the effects of a 3-day consecutive CO2-rich cold (20 °C) water immersion (CCWI) following a high-intensity intermittent test (HIIT) on subjects' sublingual temperature (Tsub), blood lactate ([La]b), and heart rate (HR) compared to cold (20 °C) tap-water immersion (CWI) or passive recovery (PAS). MethodsThirty-two subjects were randomly allocated into three groups (CCWI, CWI, and PAS), each of which completed 4 consecutive days of cycling experiments. HR, Tsub, and [La]b were recorded on each day of exercise testing (immersion from Day 1 to Day 3 and Day 4). HIIT consisted of 8 sets of 20-sec maximum exercise at an intensity of 120% of VO2max with 10-sec passive rest. The mean and peak power, and peak pedal repetitions (PPR) within HIIT were averaged and the decline in PPR (ΔPPR) from Day 1 to Day 4 was measured. ResultsIn CCWI and CWI, HR declined significantly following each immersion, with CCWI showing the larger reduction (p < 0.001). At Day 2, CCWI showed a significantly lower [La]b compared to PAS (p < 0.01). The changes in mean and peak power from Day 1 to Day 4 did not differ among the groups (p = 0.302). ΔPPR of HIIT was significantly correlated with the HR and [La]b values after immersions (ΔPPR-HR: r2 = 0.938, p < 0.001, ΔPPR-[La]b: r2 = 0.999, p < 0.001). ConclusionsThese findings indicate that CCWI is a promising intervention for maintaining peak performance in high-intensity intermittent exercise, which is associated with a reduction in [La]b and HR.

Role of Creatine Supplementation in Conditions Involving Mitochondrial Dysfunction: A Narrative Review.

Creatine monohydrate (CrM) is one of the most widely used nutritional supplements among active individuals and athletes to improve high-intensity exercise performance and training adaptations. However, research suggests that CrM supplementation may also serve as a therapeutic tool in the management of some chronic and traumatic diseases. Creatine supplementation has been reported to improve high-energy phosphate availability as well as have antioxidative, neuroprotective, anti-lactatic, and calcium-homoeostatic effects. These characteristics may have a direct impact on mitochondrion’s survival and health particularly during stressful conditions such as ischemia and injury. This narrative review discusses current scientific evidence for use or supplemental CrM as a therapeutic agent during conditions associated with mitochondrial dysfunction. Based on this analysis, it appears that CrM supplementation may have a role in improving cellular bioenergetics in several mitochondrial dysfunction-related diseases, ischemic conditions, and injury pathology and thereby could provide therapeutic benefit in the management of these conditions. However, larger clinical trials are needed to explore these potential therapeutic applications before definitive conclusions can be drawn.

The Effects of Dietary Nitrate Supplementation on Explosive Exercise Performance: A Systematic Review.

Dietary nitrate supplementation is evidenced to induce physiological effects on skeletal muscle function in fast-twitch muscle fibers and may enhance high-intensity exercise performance. An important component of sport-specific skills is the ability to perform explosive movements; however, it is unclear if nitrate supplementation can impact explosive efforts. We examined the existing evidence to determine whether nitrate supplementation improves explosive efforts lasting ≤ 6 s. PubMed, Scopus and Directory of Open Access Journals (DOAJ) were searched for articles using the following search strategy: (nitrate OR nitrite OR beetroot) AND (supplement OR supplementation) AND (explosive OR power OR high intensity OR high-intensity OR sprint* OR “athletic performance”). Out of 810 studies, 18 were eligible according to inclusion criteria. Results showed that 4 of the 10 sprint-type studies observed improved sprint time, power output, and total work in cycling or running, whereas 4 of the 10 resistance-based exercise studies observed improvements to power and velocity of free-weight bench press as well as isokinetic knee extension and flexion at certain angular velocities. These results suggest that nitrate potentially improves explosive exercise performance, but further work is required to clarify the factors influencing the efficacy of nitrate in different exercise modalities.

Effects of sodium bicarbonate ingestion on prolonged running performance and recovery in trained runners

Background: While the effects of sodium bicarbonate on buffering capacity have been repeatedly examined on short-term and high-intensity exercise performance, studies on prolonged endurance performances such as running are scarce. Thus, the purpose of this study was to investigate the effect of NaHCO? (0.3 g/kgBW) ingestion 60-minutes prior to the prolonged running testing and recovery in trained runners.Methods: A total of 10 trained male runners (age: 20.70±1.10 years; weight: 61.30±6.20 kg; height: 166.10±3.70 cm; VO2max 58.43±5.62 mL/kg/min) were recruited in this study. Subjects undertook 1 preliminary testing and 2 experimental trials: Sodium Bicarbonate (SB) and Placebo (PLA) trials, which consisted of: (i) a 60-minutes Prolonged Exercise Testing (PET) (30-minutes of constant speed run at 65 % of VO2max followed by a self-selected speed of 30-minutes maximum distance run) and (ii) 30-minutes of the recovery period in randomized order. Data were analyzed using SPSS version 23 for Windows.Results: Subjects ran further during the SB trial than the PLA trial (5,233.60±524.70 m vs. 5,021.40±440.10 m; p=0.012) associated with a greater blood lactate level (5.66±1.09 mmol/L vs. 3.68±0.71 mmol/L). Ingestion of SB drinks significantly increased urine pH during PET and recovery period (p&lt;0.01). During post-recovery, a greater decrease in blood lactate level was found in the SB trial (2.53±0.91 mmol/L; 55%) as compared to the PLA trial (2.17±0.50 mmol/L; 41%) (p&lt;0.01).Conclusion: The ingestion of NaHCO?(0.30 g/kgBW) 60-minutes prior to the PET improved prolonged running performance associated with a faster lactate removal rate during the 30-minutes recovery period.

Comparing Acute, High Dietary Protein and Carbohydrate Intake on Transcriptional Biomarkers, Fuel Utilisation and Exercise Performance in Trained Male Runners

Manipulating dietary macronutrient intake may modulate adaptive responses to exercise, and improve endurance performance. However, there is controversy as to the impact of short-term dietary modification on athletic performance. In a parallel-groups, repeated measures study, 16 trained endurance runners (maximal oxygen uptake (O2max): 64.2 ± 5.6 mL·kg−1·min−1) were randomly assigned to, and provided with, either a high-protein, reduced-carbohydrate (PRO) or a high-carbohydrate (CHO) isocaloric-matched diet. Participants maintained their training load over 21-consecutive days with dietary intake consisting of 7-days habitual intake (T1), 7-days intervention diet (T2) and 7-days return to habitual intake (T3). Following each 7-day dietary period (T1–T3), a micro-muscle biopsy was taken for assessment of gene expression, before participants underwent laboratory assessment of a 10 km treadmill run at 75% O2max, followed by a 95% O2max time to exhaustion (TTE) trial. The PRO diet resulted in a modest change (1.37-fold increase, p = 0.016) in AMPK expression, coupled with a significant increase in fat oxidation (0.29 ± 0.05 to 0.59 ± 0.05 g·min−1, p < 0.0001). However, a significant reduction of 23.3% (p = 0.0003) in TTE post intervention was observed; this reverted back to pre levels following a return to the habitual diet. In the CHO group, whilst no change in sub-maximal fuel utilisation occurred at T2, a significant 6.5% increase in TTE performance (p = 0.05), and a modest, but significant, increase in AMPK (p = 0.042) and PPAR (p = 0.029) mRNA expression compared to T1 were observed; with AMPK (p = 0.011) and PPAR (p = 0.044) remaining significantly elevated at T3. In conclusion, a 7-day isocaloric high protein diet significantly compromised high intensity exercise performance in trained runners with no real benefit on gene markers of training adaptation. A significant increase in fat oxidation during submaximal exercise was observed post PRO intervention, but this returned to pre levels once the habitual diet was re-introduced, suggesting that the response was driven via fuel availability rather than cellular adaptation. A short-term high protein, low carbohydrate diet in combination with endurance training is not preferential for endurance running performance.

Effect of Acute and Chronic Oral l-Carnitine Supplementation on Exercise Performance Based on the Exercise Intensity: A Systematic Review.

l-Carnitine (l-C) and any of its forms (glycine-propionyl l-Carnitine (GPL-C) or l-Carnitine l-tartrate (l-CLT)) has been frequently recommended as a supplement to improve sports performance due to, among others, its role in fat metabolism and in maintaining the mitochondrial acetyl-CoA/CoA ratio. The main aim of the present systematic review was to determine the effects of oral l-C supplementation on moderate- (50–79% O2 max) and high-intensity (≥80% O2 max) exercise performance and to show the effective doses and ideal timing of its intake. A structured search was performed according to the PRISMA® statement and the PICOS guidelines in the Web of Science (WOS) and Scopus databases, including selected data obtained up to 24 October 2021. The search included studies where l-C or glycine-propionyl l-Carnitine (GPL-C) supplementation was compared with a placebo in an identical situation and tested its effects on high and/or low–moderate performance. The trials that used the supplementation of l-C together with additional supplements were eliminated. There were no applied filters on physical fitness level, race, or age of the participants. The methodological quality of studies was evaluated by the McMaster Critical Review Form. Of the 220 articles obtained, 11 were finally included in this systematic review. Six studies used l-C, while three studies used l-CLT, and two others combined the molecule propionyl l-Carnitine (PL-C) with GPL-C. Five studies analyzed chronic supplementation (4–24 weeks) and six studies used an acute administration (<7 days). The administration doses in this chronic supplementation varied from 1 to 3 g/day; in acute supplementation, oral l-C supplementation doses ranged from 3 to 4 g. On the one hand, the effects of oral l-C supplementation on high-intensity exercise performance variables were analyzed in nine studies. Four of them measured the effects of chronic supplementation (lower rating of perceived exertion (RPE) after 30 min at 80% O2 max on cycle ergometer and higher work capacity in “all-out” tests, peak power in a Wingate test, and the number of repetitions and volume lifted in leg press exercises), and five studies analyzed the effects of acute supplementation (lower RPE after graded exercise test on the treadmill until exhaustion and higher peak and average power in the Wingate cycle ergometer test). On the other hand, the effects of l-C supplementation on moderate exercise performance variables were observed in six studies. Out of those, three measured the effect of an acute supplementation, and three described the effect of a chronic supplementation, but no significant improvements on performance were found. In summary, l-C supplementation with 3 to 4 g ingested between 60 and 90 min before testing or 2 to 2.72 g/day for 9 to 24 weeks improved high-intensity exercise performance. However, chronic or acute l-C or GPL-C supplementation did not present improvements on moderate exercise performance.

Effects of High-Intensity Exercise Repetition Number During Warm-up on Physiological Responses, Perceptions, Readiness, and Performance

ABSTRACT Purpose: We investigated whether varying the number of repetitions of high-intensity exercise during work-matched warm-ups modulates physiological responses (heart rate, metabolic responses, and core temperature), perceptions (ratings of perceived exertion, effort of breathing), readiness for exercise, and short-term exercise performance. Methods: Ten physically active young males performed a 30-s Wingate anaerobic test (WAnT) following a warm-up consisting of submaximal constant-workload cycling at 60% maximal oxygen uptake with no high-intensity cycling (constant-workload warm-up) or with 1, 4, or 7 repetitions of 10 s of high-intensity cycling at 110% maximal oxygen uptake. All warm-ups were matched for duration (10 min) and total work. Results: Warm-ups with seven repetitions of high-intensity cycling resulted in higher ratings of perceived whole-body exertion and effort of breathing than the constant-workload warm-up. Warm-up with four repetitions of high-intensity cycling produced greater readiness for a 30-s WAnT (7.33 ± 0.73 AU) than the constant-workload warm-up (6.33 ± 0.98 AU) (P = .022). Physiological responses did not differ among the four warm-up conditions, though peak heart rate was slightly higher (~5 beats/min) during warm-up with four or seven repetitions of high-intensity cycling than during the constant-workload warm-up. Peak, mean, and minimum power output during the 30-s WAnT did not differ among the four warm-up conditions. Conclusions: These results suggest that the effects of warm-ups with intermittent high-intensity exercise on physiological responses and short-term high-intensity exercise performance do not greatly differ from a warm-up with a work-matched submaximal constant-workload. However, they appear to modulate perceptions and readiness as a function of the number of repetitions of the high-intensity exercise.