Endurance Exercise Performance Research Articles

Improving Endurance Exercise Performance at High Altitude: Traditional and Non-traditional Approaches.

Acute exposure to terrestrial altitude (hypobaric hypoxia) causes decrements in endurance performance relative to sea level. Altitude acclimatization consistently results in partial attenuation of these decrements, but due to logistical challenges is not readily implemented. We discuss mechanisms and impact (or lack thereof) of other non-acclimatization interventions to improve endurance performance and provide suggestions future research directions.

Brain Endurance Training Improves and Maintains Chest Press and Squat Jump Performance When Fatigued.

Díaz-García, J, López-Gajardo, MÁ, Parraca, JA, Batalla, N, López-Rodríguez, R, and Ring, C. Brain endurance training improves and maintains chest press and squat jump performance when fatigued. J Strength Cond Res 38(9): 1568-1575, 2024-Mental fatigue can impair resistance exercise performance. Brain endurance training (BET)-the addition of demanding cognitive tasks to standard exercise training-improves endurance exercise performance more than standard training. Although BET has yet to be evaluated with resistance exercise, it is expected to improve performance, particularly when the performer feels mentally fatigued. The study employed a pretest (week 0), midtest (week 3), posttest (week 6), and follow-up (week 9) design, with subjects randomized to BET ( n = 46) or control (exercise training) ( n = 45) groups. In testing sessions, subjects performed chest press and squat jump exercises to failure before (feeling fresh) and after (feeling tired) a 30-minute cognitively demanding Stroop task. Training comprised 5 BET or control training sessions per week for 6 weeks. In each training session, subjects completed 4 sets of each exercise to failure, with each exercise set preceded by a 3-minute cognitive task (BET) or rest (control). Exercise performance (number of repetitions to failure) and mental fatigue markers were assessed. In pretesting, exercise performance did not differ between the groups. In midtesting and posttesting, BET performed more chest press and squat jump repetitions when fatigued by the 30-minute Stroop than control. The mental fatigue elicited by the Stroop task gradually declined with training in BET compared with control. In conclusion, BET enhanced resistance exercise performance compared with standard training when tested subsequent to a mentally fatiguing cognitive task. These benefits were maintained weeks after training ended. Brain endurance training is an effective method to mitigate the deleterious effects of mental fatigue on resistance exercise performance.

Montmorency cherry supplementation enhances 15km cycling time trial performance: Optimal timing 90-min pre-exercise.

Montmorency cherry (MC) can improve endurance performance, but optimal pre-exercise timing of supplementation and influence of training status on efficacy are unknown. We investigated the effect of MC concentrate ingestion between 30- and 150-min pre-exercise in trained and recreational cyclists on 15-km time trial (TT) performance and exercise economy. Twenty participants (10 recreationally active, RA; 10 trained, T) completed 10min of steady-state exercise (SSE) at 40%Δ (SSE) and a TT on four separate occasions following an unsupplemented (US), 30-, 90- or 150-min pre-exercise Montmorency cherry concentrate (MCC) supplementation conditions (MCC30/90/150min). Venous and capillary blood samples were taken at regular intervals pre- and post-SSE and TT. MCC significantly improved TT performance, but not exercise economy. The greatest improvement in performance occurred following MCC90min compared to US (US 1603.1±248s vs. MCC90min 1554.8±226.7s, 2.83% performance improvement). Performance was significantly enhanced for trained (US 1496.6±173.1s vs. MCC90min 1466.8±157.6s) but not recreationally active participants. Capillary [lactate] and heart rate were significantly greater during the TT for the 90-min dose timing (p<0.05). In the MCC30min and MCC90min conditions, plasma ferulic (US 8.71±3.22nmol. L-1 vs. MCC30min 15.80±8.69nmol. L-1, MCC90min 12.65±4.84nmol. L-1) and vanillic acid (US 25.14±10.91nmol.L-1 vs. MCC30min 153.07±85.91nmol. L-1, MCC90min 164.58±59.06nmol. L-1) were significantly higher pre-exercise than in US and MCC150min conditions (p<0.05). There was no significant change in muscle oxygenation status or plasma nitrite/nitrate concentration. MCC supplementation enhanced endurance exercise performance optimally when consumed ∼90min pre-exercise producing maximal plasma phenolic metabolites during exercise. The ergogenic effect was greater for trained participants.

Effects of isolated and combined mental and physical fatigue on motor skill and endurance exercise performance

BackgroundMental fatigue, elicited by cognitive demands, can impair sport and exercise performance. The effects of isolated mental fatigue on performance are well documented but few studies have explored the effects of combined mental and physical fatigue on skilled motor and endurance exercise performance. ObjectiveThis study explored the effects of isolated mental, isolated physical, and combined (mental plus physical) fatigue on skill and exercise task performance. Method164 athletes were randomly assigned to 1 of 4 groups: mental fatigue, physical fatigue, combined fatigue, control (no fatigue). Mental fatigue was induced by a 15-min time-load dual-back cognitive task. Physical fatigue was induced by a 90-s burpee exercise task. Next, all participants completed a throwing skill task and performed burpee exercises to failure. Objective (brief Psychomotor Vigilance Task, PVT-B) and subjective (self-report) measures of mental fatigue and Ratings of Perceived Exertion were obtained throughout. ResultsThe mental fatigue and combined fatigue groups performed the worst on both the throwing and burpee tasks compared with the physical fatigue and control groups. The former reported higher mental fatigue throughout and had worse response accuracy and variation on the end-of-session PVT-B task. The combined fatigue group performed better than the mental fatigue group on the throwing and burpee tasks. ConclusionA demanding cognitive task induced a state of mental fatigue and impaired skill and endurance performance. Mental fatigue alone was more detrimental than combined fatigue to skill and endurance performance, suggesting that the physical activity manipulation reduced the negative effects of mental fatigue on performance.

MicroRNA-1 Regulates Metabolic Flexibility in Skeletal Muscle via Pyruvate Metabolism.

MicroRNA-1 (miR-1) is the most abundant miRNA in adult skeletal muscle. To determine the function of miR-1 in adult skeletal muscle, we generated an inducible, skeletal muscle-specific miR-1 knockout (KO) mouse. Integration of RNA-sequencing (RNA-seq) data from miR-1 KO muscle with Argonaute 2 enhanced crosslinking and immunoprecipitation sequencing (AGO2 eCLIP-seq) from human skeletal muscle identified miR-1 target genes involved with glycolysis and pyruvate metabolism. The loss of miR-1 in skeletal muscle induced cancer-like metabolic reprogramming, as shown by higher pyruvate kinase muscle isozyme M2 (PKM2) protein levels, which promoted glycolysis. Comprehensive bioenergetic and metabolic phenotyping combined with skeletal muscle proteomics and metabolomics further demonstrated that miR-1 KO induced metabolic inflexibility as a result of pyruvate oxidation resistance. While the genetic loss of miR-1 reduced endurance exercise performance in mice and in C. elegans, the physiological down-regulation of miR-1 expression in response to a hypertrophic stimulus in both humans and mice causes a similar metabolic reprogramming that supports muscle cell growth. Taken together, these data identify a novel post-translational mechanism of adult skeletal muscle metabolism regulation mediated by miR-1.

High vs. low glycaemic index pre-exercise feeding

Carbohydrates are proven to be the most important energy source to skeletal muscle during endurance exercise. However, the glucose that carbohydrates provide the muscle with can differ in how quickly they are digested and released into the bloodstream. High glycaemic index (GI) carbohydrates are released into the bloodstream in a rapid burst following digestion whereas low GI carbohydrates are released into the bloodstream at a constant rate after consumption. The effects of low and high GI carbohydrate consumption pre-exercise on endurance exercise performance are not comprehensively understood. Therefore, the aim of this study is to identify the impact of low vs high GI pre-exercise feeding on maximal effort endurance exercise performance. With institutional ethics approval, twelve physically active, healthy males aged 18-40 years attended the laboratory on four separate occasions. On the first occasion, participants underwent a V̇O2max test to identify their maximal aerobic capacity. The final three lab visits consisted of the participants undergoing trials under three differing conditions upon arrival in the fasted state (participants were instructed to not consume food or drink other than water 6 h before arrival). The trial entailed of 20 km cycling followed by 5 km running with 2 min rest in between. Upon arrival, the participants received a carbohydrate beverage, either 40 g high GI, 40 g low GI, or a placebo, 15 min before exercising. Before consumption of the beverage, before the onset of exercise, after each 5 km during the cycle and following the run, heart rate and RPE were recorded, and a finger prick blood sample was taken to analyse for blood glucose and blood lactate concentrations throughout the exercise bout. However, the primary performance indicator was the overall time to complete the trial (bike and run minus 2 min rest). The final order of mean completion time across conditions from fastest to slowest went low GI, high GI, placebo. There was no significant difference between the mean time to completion in the low GI and high GI conditions. However, the low GI condition resulted in a faster time to completion than the placebo condition (P = 0.02) as well as the high GI condition resulting in a faster time to completion than the placebo condition (P = 0.043). Therefore, this could demonstrate that the presence of any carbohydrate type is more influential on endurance exercise performance rather than the glycaemic index of such carbohydrates.

Arginine Regulates Skeletal Muscle Fiber Type Formation via mTOR Signaling Pathway.

The composition of skeletal muscle fiber types affects the quality of livestock meat and human athletic performance and health. L-arginine (Arg), a semi-essential amino acid, has been observed to promote the formation of slow-twitch muscle fibers in animal models. However, the precise molecular mechanisms are still unclear. This study investigates the role of Arg in skeletal muscle fiber composition and mitochondrial function through the mTOR signaling pathway. In vivo, 4-week C56BL/6J male mice were divided into three treatment groups and fed a basal diet supplemented with different concentrations of Arg in their drinking water. The trial lasted 7 weeks. The results show that Arg supplementation significantly improved endurance exercise performance, along with increased SDH enzyme activity and upregulated expression of the MyHC I, MyHC IIA, PGC-1α, and NRF1 genes in the gastrocnemius (GAS) and quadriceps (QUA) muscles compared to the control group. In addition, Arg activated the mTOR signaling pathway in the skeletal muscle of mice. In vitro experiments using cultured C2C12 myotubes demonstrated that Arg elevated the expression of slow-fiber genes (MyHC I and Tnnt1) as well as mitochondrial genes (PGC-1α, TFAM, MEF2C, and NRF1), whereas the effects of Arg were inhibited by the mTOR inhibitor rapamycin. In conclusion, these findings suggest that Arg modulates skeletal muscle fiber type towards slow-twitch fibers and enhances mitochondrial functions by upregulating gene expression through the mTOR signaling pathway.

The Effect of Cannabidiol on Subjective Responses to Endurance Exercise: A Randomised Controlled Trial

BackgroundExercise is known to improve health. However, it can be unpleasant, often inducing negative feelings, or ‘affect’. Cannabidiol (CBD), a non-intoxicating constituent of the cannabis plant, has been reported to enhance the subjective experience of exercise; specifically, in trained individuals performing fixed-intensity endurance activity. Here, we investigated the effects of CBD on subjective responses to exercise under more ecologically valid conditions; namely, in recreationally active individuals performing self-paced endurance activity.MethodsA randomised, double-blind, placebo-controlled, crossover trial was conducted at Griffith University between July 17 and August 28, 2023. Griffith University students studying sports nutrition were invited to take part, with eligible volunteers ≥ 18 years of age and able to perform endurance exercise. Participants ingested placebo or 150 mg CBD in two soft-gel capsules 90 min before completing a self-paced 25-lap (10 km) run around an outdoor athletics track (400 m, synthetic). The primary outcomes were affective valence during exercise, assessed on completion of laps 6, 12, 18 and 24 using the ‘Feelings Scale’, and positive and negative affect, assessed at baseline, pre-run and post-run using the ‘Positive and Negative Affect Schedule’. Exercise enjoyment, motivation and self-efficacy, the core features of the ‘runner’s high’ (i.e., euphoria, pain, anxiety, sedation), perceived exertion and run time were also assessed.ResultsFifty-two participants were randomised and 51 were included in the final sample (n = 22 female; 22 [21–25] years). Exercise induced negative affect (i.e., at the time of undertaking) and increased pain. CBD did not counteract either response. In fact, CBD had no significant effects on any of the outcomes measured. In contrast, exercise, once completed, increased positive affect, and decreased negative affect and anxiety.ConclusionsCBD (150 mg, oral) does not appear to enhance the subjective experience of self-paced endurance exercise in recreationally active individuals. Nor, however, does it appear to compromise it. These findings suggest that CBD use is safe under exercise conditions and unlikely to impede physical activity participation. Our study also reaffirms the powerful mood-enhancing effects of exercise.Trial RegistrationRegistered with the Australian New Zealand Clinical Trials Registry (www.anzctr.org.au) on May 31, 2023 (Trial ID: ACTRN12623000593639).

Improving hydration in underhydrated, free-living young adults results in better running performance

Dehydration impairs endurance exercise performance, especially in the heat. However, it is unclear how exercise performance is affected by improved hydration status in underhydrated individuals. Therefore, this study examined the impact of a one-week hydration intervention on endurance running performance. We hypothesized better hydration would lead to a faster 2-mile running time. Eighty-nine healthy and moderately fit individuals completed a 2-mile run as fast as possible before (PRE) and after (POST) a 1-week hydration intervention. Performance was incentivized by providing prize money based on ranked average times. First-morning urine samples were collected on the day of each run. If PRE urine specific gravity was &gt;1.020, the subjects were instructed to increase their water intake for one week before the second run. The remaining subjects were instructed to maintain their water intake. All subjects were provided with a filter water bottle. Of the 89 subjects that completed both runs, 44 (18% female, age: 21±2 y, weight: 73.3±12.5 kg, height: 1.76±0.10 m, body mass index: 23.6±3.2 kg/m2) were included in the analysis. Subjects were classified as improved hydration (IMP) if UOsm decreased between PRE and POST by ≥100 mmol/kg and POST was &lt;800 mmol/kg. Subjects were classified as diminished hydration (DIM) if UOsm increased between PRE and POST by ≥100 mmol/kg and POST was &gt;500 mmol/kg. The subjects were removed from the analysis if they met any of the following three conditions: a) had a small UOsm change (&lt;100 mmol/kg) between PRE and POST, b) lowered UOSM but it was still &gt;800 mmol/kg, and c) increased UOsm but it was still &lt;500 mmol/kg. The 2-mile runs took place in Phoenix, Arizona, during the morning (0700 hours) with a maximum ambient temperature of 22±2℃, relative humidity of 37±10%, and WBGT of 16±2℃. UOsm significantly decreased for IMP from PRE: 791±197 to POST: 419±136 mmol/kg (p&lt;0.05) and increased for DIM from PRE: 532±283 to POST: 799±235 mmol/kg (p&lt;0.05). The 2-mile run time significantly improved in IMP from PRE: 13.5±1.8 to POST: 13.3±1.8 min (-11.4±25.8 sec, P=0.03), but did not change in DIM from PRE: 14.2±2.7 to POST: 14.3±2.6 min (+4.8±19.9 sec, P&gt;0.05). The results suggest that improving hydration in underhydrated subjects via one week of increased water intake may improve 2-mile running performance in moderately fit individuals. This study was funded by a grant from the Arizona State University’s Global Sport Institute. Brita donated the filter water bottles. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effects of probiotic supplementation on 12 min run performance, mood management, body composition and gut microbiota in amateur marathon runners: A double-blind controlled trial

BackgroundProbiotic supplementation has a positive effect on endurance exercise performance and body composition in athletes, but the underlying mechanisms remain unclear. Gut microbiota can provide measurable markers of immune function in athletes, and microbial composition analysis may be sensitive enough to detect stress and metabolic disorders caused by exercise. MethodsNineteen healthy active amateur marathon runners (15 male and 4 female) with a mean age of 29.11 years volunteered to participate in this double-blind controlled study. Based on the performance of the Cooper 12-min running test (CRT), the participants were allocated into two groups to receive either a probiotic formulation comprising lactobacillus acidophilus and bifidobacterium longum (n = 10) or placebo containing maltodextrin (n = 9) for five weeks. Consistency of diet and exercise was ensured throughout the experimental period. Before and after the intervention, all participants were assessed for CRT, emotional stability and gastrointestinal symptoms, gut microbiota composition, body composition and magnetic resonance imaging (MRI) indicators of skeletal muscle microcirculation. ResultsCompared to before the intervention, the probiotics group showed an increase in CRT score (2.88 ± 0.57 vs 3.01 ± 0.60 km, P＜0.05), significant improvement in GSRS and GIQLI (9.20 ± 4.64 vs 7.40 ± 3.24, 118.90 ± 12.30 vs 127.50 ± 9.85, P＜0.05), while these indicators remained unchanged in the control group, with a significant time-group interaction effect on gastrointestinal symptoms. Additionally, some MRI metabolic cycling indicators of the thigh skeletal muscle also changed in the probiotics group (P＜0.05). Regarding microbiota abundance, the probiotics group exhibited a significant increase in the abundance of beneficial bacteria and a significant decrease in the abundance of harmful bacteria post-intervention (P＜0.05). ConclusionAs a sports nutritional supplement, probiotics have the potential to improve athletic performance by optimizing the balance of gut microbiota, alleviating gastrointestinal symptoms.

Low-Volume Speed Endurance Training with Reduced Volume Improves Short-Term Exercise Performance in Highly Trained Cyclists.

We investigated the effects of low- and high-volume speed endurance training (SET), with a reduced training volume, on sprint ability, short- and long-term exercise capacity, muscle mitochondrial properties, ion transport proteins, and maximal enzyme activity in highly trained athletes. Highly trained male cyclists (maximal oxygen consumption (V̇O 2max ): 68.3 ± 5.0 mL·min -1 ·kg -1 , n = 24) completed 6 wk of either low (SET-L; 6 × 30-s intervals, n = 8) or high (SET-H; 12 × 30-s intervals, n = 8) volume SET twice per week with a 30% reduction in training volume. A control group (CON; n = 8) maintained their training. Exercise performance was evaluated by i) 6-s sprinting, ii) a 4-min time trial, and iii) a 60-min preload at 60% V̇O 2max followed by a 20-min time trial. A biopsy of m. vastus lateralis was collected before and after the training intervention. In SET-L, 4-min time trial performance was improved ( P < 0.05) by 3.8%, with no change in SET-H and CON. Sprint ability, prolonged endurance exercise capacity, V̇O 2max , muscle mitochondrial respiratory capacity, maximal citrate synthase activity, fiber type-specific mitochondrial proteins (complexes I-V), and phosphofructokinase (PFK) content did not change in any of the groups. In SET-H, maximal activity of muscle PFK and abundance of Na + -K + pump-subunit α 1 , α 2 , β 1 , and phospholemman (FXYD1) were 20%, 50%, 19%, 24%, and 42% higher ( P < 0.05), respectively after compared with before the intervention, with no changes in SET-L or CON. Low SET volume combined with a reduced aerobic low- and moderate-intensity training volume does improve short-duration intense exercise performance and maintain sprinting ability, V̇O 2max , endurance exercise performance, and muscle oxidative capacity, whereas, high volume of SET seems necessary to upregulate muscle ion transporter content and maximal PFK activity in highly trained cyclists.

Endurance exercise associated with a fructooligosaccharide diet modulates gut microbiota and increases colon absorptive area.

Fructooligosaccharide (FOS) supplementation can stimulate beneficial intestinal bacteria growth, but little is known about its influence on training performance. Therefore, this study analyzed FOS and exercise effects on gut microbiota and intestinal morphology of C57Bl/6 mice. Forty male mice were divided into four groups: standard diet-sedentary (SDS), standard diet-exercised (SDE), FOS supplemented (7.5% FOS)-sedentary (FDS), and FOS supplemented-exercised (FDE), n = 10 each group. Exercise training consisted of 60 min/day, 3 days/week, for 12 weeks. SDE and FDE groups had an increase in aerobic performance compared to the pretraining period and SDS and FDS groups (P< 0.01), respectively. Groups with FOS increased colonic crypts size (P< 0.05). The FDE group presented rich microbiota (α-diversity) compared to other groups. The FDE group also acquired a greater microbial abundance (β-diversity) than other groups. The FDE group had a decrease in the Ruminococcaceae (P< 0.002) and an increase in Roseburia (P< 0.003), Enterorhabdus (P< 0.004) and Anaerotruncus (P< 0.006). These findings suggest that aerobic exercise associated with FOS supplementation modulates gut microbiota and can increase colonic crypt size without improving endurance exercise performance.

Effects of Dityrosine on Lactic Acid Metabolism in Mice Gastrocnemius Muscle During Endurance Exercise via the Oxidative Stress-Induced Mitochondria Damage.

Dityrosine (Dityr) has been detected in commercial food as a product of protein oxidation and has been shown to pose a threat to human health. This study aims to investigate whether Dityr causes a decrease in lactic acid metabolism in the gastrocnemius muscle during endurance exercise. C57BL/6 mice were administered Dityr or saline by gavage for 13 weeks and underwent an endurance exercise test on a treadmill. Dityr caused a severe reduction in motion displacement and endurance time, along with a significant increase in lactic acid accumulation in the blood and gastrocnemius muscle in mice after exercise. Dityr induced significant mitochondrial defects in the gastrocnemius muscle of mice. Additionally, Dityr induced serious oxidative stress in the gastrocnemius muscle, accompanied by inflammation, which might be one of the causes of mitochondrial dysfunction. Moreover, significant apoptosis in the gastrocnemius muscle increased after exposure to Dityr. This study confirmed that Dityr induced oxidative stress in the gastrocnemius muscle, which further caused significant mitochondrial damage in the gastrocnemius muscle cell, resulting in decreased capacity of lactic acid metabolism and finally affected performance in endurance exercise. This may be one of the possible mechanisms by which highly oxidized foods cause a decreased muscle energy metabolism.

The influence of low resistance respiratory muscle training on pulmonary function and high intensity exercise performance

Background/objectivesRespiratory muscle training (RMT) was recognized as an effective means to improve respiratory muscle (RM) strength and enhance exercise performance. The purpose of this study was to examine the effect of low-intensity RMT on RM strength, pulmonary function, and performance. MethodsFourteen healthy active adults were assigned randomly to either a training or placebo group. The training group completed six weeks of RMT, which consisted of a first week, 1 set of 15 min/d, 5 d/wk at 10–25% of maximal inspiratory pressure (PImax), and the remaining 5 weeks, 2 sets of 15 min/d, 5 d/wk, at 30% PImax. The placebo group followed the same protocol but with almost no additional ventilatory resistance. Measurement of RM strength and endurance, spirometry, and endurance exercise performance were obtained before and after the RMT program. ResultsIn the training group, PImax (+14%) and maximal expiratory pressure (PEmax, +27%), forced vital capacity (FVC, +3.6%), maximal oxygen uptake (VO2max, +11%), and time to exhaustion (Tlim90%, +25%) increased significantly from baseline values (P < 0.05). No significant changes were observed in the placebo group. Also, no significant interaction in maximum voluntary ventilation (MVV12), minute ventilation (VE), and respiratory rate (RR) were detected. ConclusionsThese data suggest that low-intensity RMT is an effective tool to improve RM strength, pulmonary elastic properties and endurance exercise performance.

Effects of acute and multi-day low-dose sodium bicarbonate intake on high-intensity endurance exercise performance in male recreational cyclists

PurposeThis study aimed to compare the effects of acute and multi-day low-dose sodium bicarbonate (SB) intake on high-intensity endurance exercise performance.MethodsIn a randomized, double-blind, cross-over design, twelve recreational male cyclists (age: 31.17 ± 4.91 years; V˙\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\dot{{\ ext{V}}}$$\\end{document}O2peak: 47.98 ± 7.68 ml·kg−1·min−1) completed three endurance performance tests following acute SB (ASB, 0.2 g·kg−1 SB), multi-day SB (MSB, 0.2 g·kg−1·day−1 SB for four days), and placebo (PLA) intake. The high-intensity endurance performance was assessed with a cycling exercise test, wherein participants cycled on a bicycle ergometer at 95% of the predetermined anaerobic threshold for 30 min, followed by a time-to-exhaustion test at 110% of the anaerobic threshold. Data were analyzed using one-way and two-way repeated-measures ANOVA.ResultsSignificant main effects of supplementation protocol were evident in pre-exercise bicarbonate concentrations (F = 27.93; p < 0.01; partial eta squared (η2) = 0.72; false discovery rate (FDR)-adjusted p value = 0.001). Prior to performance test, blood bicarbonate concentrations were significantly higher in MSB (25.78 ± 1.63 mmol·L−1 [95% CI 26.55–28.44] (p < 0.001; FDR-adjusted p value = 0.001)) and ASB (27.49 ± 1.49 mmol·L−1 [95% CI 24.75–26.81] (p < 0.001; FDR-adjusted p value = 0.007)) compared to PLA (23.75 ± 1.40 mmol·L−1 [95% CI 22.86 to 24.64]). Time-to-exhaustion increased in MSB (54.27 ± 9.20 min [95% CI 48.43–60.12]) compared to PLA (49.75 ± 10.80 min [95% CI 42.89–56.62]) (p = 0.048); however, this increase in MSB did not reach the significance threshold of 1% FDR (FDR-adjusted p value = 0.040). No significant difference was noted in exhaustion times between ASB (51.15 ± 8.39 min [95% CI 45.82–56.48]) and PLA (p > 0.05).ConclusionBoth acute and multi-day administration of low-dose SB improves buffering system in cyclists; nevertheless, neither intervention demonstrates sufficient efficacy in enhancing high-intensity endurance performance.

Echocardiographic assessment of myocardial efficiency predicts exercise performance

AbstractCardiac function is a major determinant of cardiopulmonary fitness. This study aimed to determine if novel echocardiographic myocardial function and efficiency parameters at rest can predict exercise performance during different types of prolonged high‐intensity endurance exercise. Echocardiography was performed before exercise in 40 healthy (75% males) 50.3 ± 9.1‐year‐old recreational athletes. Echocardiographic parameters at rest were compared with exercise performance assessed by power output during two different exercises: A lactate threshold and cardiopulmonary exercise test (La‐CPET) and a 91‐km mountain bike sport cycling race. The La‐CPET had a median duration of 43 (40, 45) minutes and a mean power output of 2.9 ± 0.5 W/kg. The race had a median duration of 236 (214, 268) minutes and a mean power output of 2.1 ± 0.5 W/kg. There was moderate left ventricular (LV) dilatation in individuals with the highest performance. The myocardial efficiency parameter, global wasted work (GWW), was positively correlated with race duration (rho = 0.42, p = 0.008) and negatively correlated with mean power output during both the La‐CPET (rho = −0.43, p = 0.007) and the race (rho = −0.44, p = 0.005). In multivariable models, including LV volumes, left GWW remained an independent predictor of race duration (beta = 0.40, p = 0.007) and of mean power output during the La‐CPET (beta = −0.40, p = 0.006) and the race (beta = −0.43, p = 0.003). The novel echocardiographic myocardial efficiency parameter, GWW, measured at rest, is an independent predictor of prolonged high‐intensity endurance exercise performance in healthy middle‐aged athletes. These findings suggest that resting myocardial efficiency parameters may aid the identification of exercise‐induced LV dilatation.

The effect of pre-exercise oral hyperhydration on endurance exercise performance, heart rate, and thermoregulation: a meta-analytical review.

This study aimed to determine the effect of pre-exercise hyperhydration on endurance performance (primary outcome), heart rate, thermoregulation, and perceptual responses (secondary outcomes). Six academic databases were searched to February 2023. Only studies reporting differences in hydration between intervention and placebo/control were included. Meta-analysis determined overall effect size (Hedges' g), and meta-regression the influence of independent moderators (ambient temperature, hyperhydration agent, exercise mode, extent of hyperhydration). Overall, 10 publications generating 19 effect estimates for primary outcomes, and 11 publications reporting 48 effect estimates for secondary outcomes, were included. A small-to-moderate improvement in time-to-exhaustion (TTE) (Hedges' g=0.31, 95% CI: 0.13-0.50, p=0.001) and time trial (TT) (g=0.25, 95% CI: 0.002-0.51, p=0.049) but not total work (TW) tasks (p=0.120) was found following hyperhydration. No moderating effects were observed. No effect of hyperhydration was found for heart rate following steady state (SS) exercise (p=0.069) or the performance task (p=0.072), nor for body temperature post-SS (p=0.132) or post-performance task (p=0.349), but meta-regression of sodium versus glycerol showed lower body temperature post-performance task with sodium (g=0.80, t (5)=2.65, p=0.046). No effects were found for perceived exertion or thermal comfort. Study heterogeneity was low, lacking representation of elite and female athletes, and weight-bearing (i.e., running) exercise modalities. These results suggest pre-exercise hyperhydration provides a small-to-moderate benefit to endurance performance in TTE and TT, but not TW performance tasks. While no moderating effects were observed, lack of heterogeneity makes it difficult to generalise these findings.

Could nanotechnology improve exercise performance? Evidence from animal studies.

This review provides the current state of knowledge regarding the use of nutritional nanocompounds on exercise performance. The reviewed studies used the following nanocompounds: resveratrol-loaded lipid nanoparticles, folic acid into layered hydroxide nanoparticle, redox-active nanoparticles with nitroxide radicals, and iron into liposomes. Most of these nutritional nanocompounds seem to improve performance in endurance exercise compared to the active compound in the non-nanoencapsulated form and/or placebo. Nutritional nanocompounds also induced the following physiological and metabolic alterations: 1) improved antioxidant activity and reduced oxidative stress; 2) reduction in inflammation status; 3) maintenance of muscle integrity; 4) improvement in mitochondrial function and quality; 5) enhanced glucose levels during exercise; 6) higher muscle and hepatic glycogen levels; and 7) increased serum and liver iron content. However, all the reviewed studies were conducted in animals (mice and rats). In conclusion, nutritional nanocompounds are a promising approach to improving exercise performance. As the studies using nutritional nanocompounds were all conducted in animals, further studies in humans are necessary to better understand the application of nutritional nanocompounds in sport and exercise science.

Topical application of L-Menthol – Physiological and genetic considerations to assist in developing female athlete research: A narrative review

L-menthol is a cyclic monoterpene derived from aromatic plants, which gives a cooling sensation upon application. With this in mind, L-menthol is beginning to be considered as a potential ergogenic aid for exercise and sporting competitions, particularly in hot environments, however female-specific research is lacking. The aim of this narrative review is to summarize available literature relating to topical application of L-menthol and provide commentary on avenues of consideration relating to future research developments of topical L-menthol in female athletes. From available studies in male participants, L-menthol topical application results in no endurance exercise performance improvements, however decreases in thermal sensation are observed. Mixed results are observed within strength performance parameters. Several genetic variations and single nucleotide polymorphisms have been identified in relation to sweat production, fluid loss and body mass changes – factors which may influence topical application of L-menthol. More specifically to female athletes, genetic variations relating to sweat responses and skin thickness, phases of the menstrual cycle, and body composition indices may affect the ergogenic effects of L-menthol topical application, via alterations in thermogenic responses, along with differing tissue distribution compared to their male counterparts. This narrative review concludes that further development of female athlete research and protocols for topical application of L-menthol is warranted due to physiological and genetic variations. Such developments would benefit research and practitioners alike with further personalized sport science strategies around phases of the menstrual cycle and body composition indices, with a view to optimize ergogenic effects of L-menthol.

Eight weeks of heavy strength training increases hemoglobin mass and V̇o2peak in well-trained to elite female and male rowers.

O2-transport and endurance exercise performance are greatly influenced by hemoglobin mass (Hbmass), which largely depends on lean body mass (LBM). This study investigated the effects of 8 wk with three weekly sessions of conventional (3-SET: 3 × 10 reps) or high-volume strength training (10-SET: 5-10 × 10 reps) on LBM, Hbmass, muscle strength, and exercise performance in female and male rowers. Hematological parameters were obtained through CO rebreathing and body composition by dual-energy X-ray absorptiometry (DEXA) scans before and after the training period. Concomitantly, V̇o2peak was determined during 2-km ergometer rowing and muscle strength by isometric midthigh pull. There were no differences in training responses between groups for any of the parameters. Pooled data revealed overall increments for Hbmass (10-SET: 882 ± 199 g to 897 ± 213 g; 3-SET: 936 ± 245 g to 962 ± 247 g, P = 0.02) and V̇o2peak (10-SET: 4.3 ± 1.0 to 4.4 ± 0.9 L·min-1; 3-SET: 4.5 ± 0.9 to 4.6 ± 0.9 L·min-1, P = 0.03), whereas LBM remained unchanged (10-SET: 58.7 ± 10.5 to 58.7 ± 10.1 kg; 3-SET: 64.1 ± 10.8 to 64.5 ± 10.6 kg, P = 0.42). Maximal isometric midthigh pull strength increased (10-SET: 224 ± 47 kg to 237 ± 55 kg; 3-SET: 256 ± 77 kg to 281 ± 83 kg, P = 0.001). Strong associations were observed between LBM and Hbmass and V̇o2peak (r2 = 0.88-0.90), entailing sex differences in Hbmass and V̇o2peak. Normalizing V̇o2peak to LBM reduced the sex difference to ∼10%, aligning with the sex difference in Hbmass·LBM-1. Strength training successfully increased Hbmass and V̇o2peak in elite female and male rowers, without an additional effect from increased training volume. Moreover, sex differences in V̇o2peak were mainly explained by differences in LBM, but likely also by differences in Hbmass·LBM-1.NEW & NOTEWORTHY This study in female and male rowers demonstrates that hemoglobin mass (Hbmass), V̇o2peak, and muscle strength increases with 8 wk of heavy strength training and that this response is not different between conventional (3 × 10 repetitions) and high-volume strength training (10 × 10 repetitions). Moreover, female rowers exhibited less hemoglobin per kilogram of lean body mass compared with their male counterparts, which likely contributes to sex differences in V̇o2peak and rowing performance.