Increase Exercise Performance Research Articles

Does 'altitude training' increase exercise performance in elite athletes?

What is the topic of this review? The aim is to evaluate the effectiveness of various altitude training strategies as investigated within the last few years. What advances does it highlight? Based on the available literature, the foundation to recommend altitude training to athletes is weak. Athletes may use one of the various altitude training strategies to improve exercise performance. The scientific support for such strategies is, however, not as sound as one would perhaps imagine. The question addressed in this review is whether altitude training should be recommended to elite athletes or not.

Effects of AquaTitan Bracelet on Quadriceps Muscle Soreness after Fatiguing Exercise

Muscular soreness can be a hindrance for athletes in exercise performance. Many use ionized bracelets during training and competition to reduce muscular soreness and increase exercise performance. PURPOSE: To examine the effect of Phiten’s Rakuwa S Cross Bracelet on quadriceps muscle soreness after fatiguing exercise (FE). METHODS: 15 recreationally active male volunteers (age: 23.87±1.55yrs, height: 174.09±5.06cm, weight: 68.69±9.70kg) participated over five weeks in a single-blinded, balanced, random crossover study. Three experimental trials (AquaTitan (AT), Placebo (P), and Control(C)) were administered, with a five-day washout period between trials. Each participant performed a FE protocol of 100 repetitions of isokinetic contraction at 60°/s on an Isokinetic Dynamometer. Perceived muscle soreness was measured using a Visual Analog Scale (VAS) immediately (Post-1) and 24 hours (Post-2) after FE. Muscle soreness tests (MST) were conducted at the vastus lateralis (VL), rectus femoris (RF), and vastus medialis (VM) muscles, followed by knee extension while seated (EXT) and knee flexion while standing (FLX). OMNI Resistance Exertion Scale (RES) was used to measure rate of perceived exertion (RPE) for muscular strength (S) and endurance (E) tests performed after MST. RESULTS: Repeated Measures ANOVA revealed significant differences in muscle soreness between Post-1 and Post-2 in VL (26.42±6.29 vs. 17.96±3.75, p=0.04), VM (38.78±5.69 vs. 28.35±4.56, p=0.02), EXT (58.73±6.46 vs. 30.38±4.31, p<0.05) and FLX (55.69±7.63 vs. 35.24±5.94, p=0.01). No significant differences were found in RF (30.62±6.55, 24.27±4.43, p=0.21), as well as between AT, P and C (39.60±5.37, 41.65±5.59, 44.89±6.17, p=0.40). There were no significant interactions between trials and post tests (VL: p=0.38, RF: p=0.05, VM: p=0.62, EXT: p=0.19, FLX: p=0.06), and no significant correlation between VAS and RPE. Participants performed maximal effort for all trials as indicated in their RPE estimation (S: AT: 8.91±0.29, P: 8.58±0.28, C: 8.76±0.27; E: AT: 9.27±0.25, P: 9.33±0.23, C: 9.31±0.22). CONCLUSION: Post-2 scores were significantly lower than post-1 regardless of the type of bracelet worn, suggesting that AquaTitan bracelets may not have an effect on increased muscular performance with a reduction of muscle soreness.

Effect Of Acute Citrulline-malate Supplementation On Muscular Power

Citrulline-malate (CM) is a nonessential amino acid that acts as a precursor to l-arginine in the nitric-oxide pathway and may increase exercise performance. While CM is shown to decrease fatigue and improve muscular endurance, there are no data evaluating the effects of CM regarding the effects on muscular power. PURPOSE: Therefore, the purpose of this investigation was to evaluate the effects of acute CM supplementation on muscular power in recreationally active females. METHODS: Fifteen females (20.6 +/- 0.8 years) completed two randomized, double blind trials consuming either CM (8 g dextrose+8 g CM) or a placebo (8 g dextrose). One hour after supplement consumption, participants performed a protocol consisting of four exercises designed to assess muscular power. Tests included vertical jump, lower-body isokinetic exercise (ISO; 5 repetition and 50 repetition protocols), and a standard Wingate cycling test. RESULTS: Throughout the 5 repetition ISO, participants experienced significantly less fatigue (p=.02), as well as substantially increasing work completed in the last third (p=.03). The Wingate cycling test found subjects significantly increased average power (p=.03), anaerobic capacity (p=.02), and total work completed (p=.02). CONCLUSION: Acute CM supplementation in females increased power and total work while mitigating fatigue. These data indicate athletes may benefit from acutely supplementing CM if they are competing in sports where increases in max anaerobic capacity, power, or decreases in fatigue are beneficial.

Antifatigue and increasing exercise performance of Actinidia arguta crude alkaloids in mice

Actinidia arguta (Siebold et Zucc.) Planch. ex. Miq. is one of the most recently domesticated fruit species with increasing commercial production worldwide. It is a well-known traditional Chinese medicine and is used to reduce blood glucose and treat atopic dermatitis. In addition, it possesses antioxidant, anticancer, and antiallergic properties. In this study, we investigated the physical antifatigue and exercise performance effects of A. arguta crude alkaloids (AACA) extracted with 70% ethanol. Four groups of male Kunming mice (n = 16) were orally administered AACA at doses of 0 mg/kg/d (vehicle), 50 mg/kg/d (AACA-50), 100 mg/kg/d (AACA-100), or 200 mg/kg/d (AACA-200) for 28 days. The effect of AACA treatment on exercise performance was studied using the forelimb grip strength experiment and by the measurement of the weight-loaded swimming time. The antifatigue effect is evaluated based on fatigue-associated biochemical parameters, hepatic and muscular glycogen levels, and changes in the morphology of transverse and longitudinal sections of skeletal muscle. The results showed that AACA could elevate the endurance and grip strength in mice. The exhaustive swimming time of the AACA-50, AACA-100, and AACA-200 groups was significantly (p < 0.05) increased compared with the vehicle. The swimming time of the AACA-100 group was the longest among all groups studied. Mice in the AACA-treated groups had decreased levels of lactate, ammonia, and creatine kinase after a physical challenge compared with the vehicle group. The tissue glycogen, an important energy source during exercise, significantly increased with AACA. The morphology of transverse and longitudinal sections of skeletal muscle did not change in the vehicle group. Overall, these findings suggest that AACA possesses antifatigue effects and increases exercise performance in mice. Therefore, A. arguta may be developed as an antifatigue dietary supplement in the category of functional foods.

Acute citrulline-malate supplementation improves maximal strength and anaerobic power in female, masters athletes tennis players

Citrulline-malate (CM) is a precursor to nitric-oxide (NO) in the NO synthase (NOS) pathway and is suggested to increase exercise performance in younger individuals. With age, NO production decreases and augmented NO production may provide beneficial effects on sports performance among masters athletes (MAs). Purpose: To examine the effects of acute CM supplementation on grip strength, vertical power, and anaerobic cycling performance in female, MA tennis players. Methods: Seventeen female MA (51 ± 9 years) completed two double-blind, randomized trials consuming CM (12 g dextrose + 8 g CM) and placebo (PLA) (12 g dextrose). One hour after consumption, subjects completed grip strength, vertical power, and Wingate anaerobic cycling assessments in respective order. Maximal and average grip strength, peak and average vertical power, anaerobic capacity, peak power, explosive power, and ability to sustain anaerobic power were calculated from the tests. Results: When consuming CM, participants exhibited greater maximal (p = .042) and average (p = .045) grip strength compared to PLA. No differences existed between trials for peak (p = .51) or average (p = .51) vertical power. For the Wingate, peak power (p < .001) and explosive power (p < .001) were significantly greater when consuming CM compared to PLA. For the ability to sustain power, a significant effect (p < .001) was observed for time within trials, but no significant differences were observed between trials regarding supplement consumed. Conclusions: These data suggest that consuming CM before competition has the potential to improve tennis match-play performance in masters tennis athletes. However, this study utilized a controlled laboratory environment and research evaluating direct application to on-court performance is warranted.

Physiological and therapeutic effects of carnosine on cardiometabolic risk and disease.

Obesity, type 2 diabetes (T2DM) and cardiovascular disease (CVD) are the most common preventable causes of morbidity and mortality worldwide. They represent major public health threat to our society. Increasing prevalence of obesity and T2DM contributes to escalating morbidity and mortality from CVD and stroke. Carnosine (β-alanyl-L-histidine) is a dipeptide with anti-inflammatory, antioxidant, anti-glycation, anti-ischaemic and chelating roles and is available as an over-the-counter food supplement. Animal evidence suggests that carnosine may offer many promising therapeutic benefits for multiple chronic diseases due to these properties. Carnosine, traditionally used in exercise physiology to increase exercise performance, has potential preventative and therapeutic benefits in obesity, insulin resistance, T2DM and diabetic microvascular and macrovascular complications (CVD and stroke) as well as number of neurological and mental health conditions. However, relatively little evidence is available in humans. Thus, future studies should focus on well-designed clinical trials to confirm or refute a potential role of carnosine in the prevention and treatment of chronic diseases in humans, in addition to advancing knowledge from the basic science and animal studies.

New strategies in sport nutrition to increase exercise performance

Despite over 50 years of research, the field of sports nutrition continues to grow at a rapid rate. Whilst the traditional research focus was one that centred on strategies to maximise competition performance, emerging data in the last decade has demonstrated how both macronutrient and micronutrient availability can play a prominent role in regulating those cell signalling pathways that modulate skeletal muscle adaptations to endurance and resistance training. Nonetheless, in the context of exercise performance, it is clear that carbohydrate (but not fat) still remains king and that carefully chosen ergogenic aids (e.g. caffeine, creatine, sodium bicarbonate, beta-alanine, nitrates) can all promote performance in the correct exercise setting. In relation to exercise training, however, it is now thought that strategic periods of reduced carbohydrate and elevated dietary protein intake may enhance training adaptations whereas high carbohydrate availability and antioxidant supplementation may actually attenuate training adaptation. Emerging evidence also suggests that vitamin D may play a regulatory role in muscle regeneration and subsequent hypertrophy following damaging forms of exercise. Finally, novel compounds (albeit largely examined in rodent models) such as epicatechins, nicotinamide riboside, resveratrol, β-hydroxy β-methylbutyrate, phosphatidic acid and ursolic acid may also promote or attenuate skeletal muscle adaptations to endurance and strength training. When taken together, it is clear that sports nutrition is very much at the heart of the Olympic motto, Citius, Altius, Fortius (faster, higher, stronger).

Effects of erythropoietin on systemic hematocrit and oxygen transport in the splenectomized horse

To test the hypotheses that erythropoietin (rhuEPO) treatment increases systemic hematocrit, maximal O2 uptake (V˙O2max, by elevated perfusive and diffusive O2 conductances) and performance five female horses (4–13 years) received 15IU/kg rhuEPO (erythropoietin) three times per week for three weeks. These horses had been splenectomized over 1 year previously to avoid confounding effects from the mobilization of splenic red blood cell reserves. Each horse performed three maximal exercise tests (one per month) on an inclined (4°) treadmill to the limit of tolerance; two control trials and one following EPO treatment. Measurements of hemoglobin concentration ([Hb] and hematocrit), plasma and blood volume, V˙O2, cardiac output as well as arterial and mixed venous blood gases were made at rest and during maximal exercise. EPO increased resting [Hb] by 18% from 13.3±0.6 to 15.7±0.8g/dL (mean±SD) corresponding to an increased hematocrit from 36±2 to 46±2% concurrent with 23 and 10% reductions in plasma and blood volume, respectively (all P<0.05). EPO elevated V˙O2max by 20% from 25.7±1.7 to 30.9±3.4L/min (P<0.05) via a 17% increase in arterial O2 content and 18% greater arteriovenous O2 difference in the face of an unchanged cardiac output. To achieve the greater V˙O2max after EPO, diffusive O2 conductance increased ∼30% (from 580±76 to 752±166mL O2/mmHg/min, P<0.05) which was substantially greater than the elevation of perfusive O2 conductance. These effects of EPO were associated with an increased exercise performance (total running time: control, 216±72; EPO, 264±48s, P<0.05). We conclude that EPO substantially increases V˙O2max and performance in the splenectomized horse via improved perfusive and diffusive O2 transport.

Can sildenafil improve physical performance at altitude? Current scientific evidence

Sildenafil has proven to efficiently reduce the increase in pulmonary artery pressure provoked by hypoxic pulmonary vasoconstriction. However, its role as a possible factor in increasing exercise performance under hypoxic conditions remains to be demonstrated. The use of sildenafil has increased among mountaineers, not as a high altitude pulmonary edema preventive drug, but as a means that could help to improve performance. Several studies have attempted to address this issue, with conflicting results. Currently, despite the inconclusive data at simulated or real altitude, and with the clear evidence that, in normoxia, sildenafil does not improve performance, this drug is being used (and sometimes overused) by people who climb high peaks. However, such potential performance improvement would depend on the degree of hypoxemia (altitude) and the individual responsiveness to this drug. This paper reviews the current knowledge on this matter.

Effects of 28-Day Beta-Alanine Supplementation on Isokinetic Exercise Performance and Body Composition in Female Masters Athletes

Beta-alanine (BA) supplementation increases exercise performance due to increases in the intramuscular lactate buffer, carnosine. Females are more sensitive to these increases and results are further pronounced in trained individuals. Baseline intramuscular carnosine levels also naturally decrease with age; therefore, trained older females may experience augmented benefits from BA supplementation. However, the ability of BA to increase lower-body isokinetic strength (ISO) in female masters athletes (MA) is unknown. The purpose of this study was to examine the longitudinal effects of BA supplementation on ISO, handgrip strength (HG), and body composition in female MA cyclists. Twenty-two subjects participated in this double-blind randomized study. Subjects were randomized into 2 groups (placebo [PLA] = 8 g dextrose; BA = 800 mg + 8 g dextrose) and supplemented 4 times per day for 28 days. ISO, HG, and body composition were evaluated at baseline and at the same day/time each week over the 28-day intervention. No differences existed between groups at baseline or at the 7, 14, and 21 days time points for any variables (p > 0.05). When evaluating ISO (isokinetic) after 28 days, total work performed during the final third of the assessment (24.0 vs. -16.8% change) in flexion and average peak torque (5.4 vs. 2.9% change) in extension were significantly increased from baseline in BA compared with PLA (p ≤ 0.05). No differences existed for HG or body composition after supplementation. Twenty-eight days of BA supplementation increased peak torque and work completed, indicating BA improves lower-body exercise performance in female MA.

Redox interventions to increase exercise performance.

Skeletal muscle continually produces reactive oxygen species (ROS) and nitric oxide (NO) derivatives. Both oxidant cascades have complex effects on muscle contraction, metabolic function and tissue perfusion. Strenuous exercise increases oxidant production by muscle, limiting performance during endurance exercise tasks. Conversely, redox interventions that modulate ROS or NO activity have the potential to improve performance. Antioxidants have long been known to buffer ROS activity and lessen oxidative perturbations during exercise. The capacity to enhance human performance varies among antioxidant categories. Vitamins, provitamins and nutriceuticals often blunt oxidative changes at the biochemical level but do not enhance performance. In contrast, reduced thiol donors have been shown to delay fatigue or increase endurance under a variety of experimental conditions. Dietary nitrate supplementation has recently emerged as a second redox strategy for increasing endurance. Purified nitrate salts and nitrate-rich foods, notably beetroot and beetroot juice, are reported to lessen the oxygen cost of exercise, increase efficiency, and enhance performance during endurance tasks. These findings are exciting but enigmatic since nitrate per se has little bioactivity and cannot be converted to NO by mammalian cells. Overall, the available data suggest exercise endurance can be augmented by redox-active supplements, either reduced thiol donors or dietary nitrates. These findings have clear implications for athletes seeking a competitive edge. More importantly, interventions that increase endurance may benefit individuals whose physical activity is limited by illness, ageing, or frailty.

Cardiovascular prevention and rehabilitation for patients with ventricular assist device From exercise therapy to long-term therapy Part I: exercise therapy

In the present context of an aging population, limited donor heart availability, improved reliability of mechanical cardiac support and improved patient outcomes, ventricular assist device (VAD) options to support end-stage heart failure patients are rapidly expanding. In addition, both the smaller size and lighter weight of the pumps now produced and early evidence that these third generation devices may be associated with lower risk of infection and right ventricular failure will probably lead to greater physician and patient acceptability. This is the first of a two-part review on the role of cardiovascular prevention and rehabilitation in patients with VAD. In this first part, we will discuss the role of exercise therapy in VAD patients, while the second will focus on long-term management. One of the prerequisites for use of a VAD--whether permanent (as destination therapy) or semi-permanent (as an alternative to heart transplantation)--is that exercise capacity, although not normal, must be adequate for daily life activities. An intensive multidisciplinary rehabilitation program has the potential to increase exercise performance and improve the quality of life of VAD patients. Both early progressive mobilization and exercise training may improve the overall condition of VAD patients, and favorably impact their clinical course.

Type 5 adenylyl cyclase disruption leads to enhanced exercise performance.

The most important physiological mechanism mediating enhanced exercise performance is increased sympathetic, beta adrenergic receptor (β-AR), and adenylyl cyclase (AC) activity. This is the first report of decreased AC activity mediating increased exercise performance. We demonstrated that AC5 disruption, that is, knock out (KO) mice, a longevity model, increases exercise performance. Importantly for its relation to longevity, exercise was also improved in old AC5 KO. The mechanism resided in skeletal muscle rather than in the heart, as confirmed by cardiac- and skeletal muscle-specific AC5 KO's, where exercise performance was no longer improved by the cardiac-specific AC5 KO, but was by the skeletal muscle-specific AC5 KO, and there was no difference in cardiac output during exercise in AC5 KO vs. WT. Mitochondrial biogenesis was a major mechanism mediating the enhanced exercise. SIRT1, FoxO3a, MEK, and the anti-oxidant, MnSOD were upregulated in AC5 KO mice. The improved exercise in the AC5 KO was blocked with either a SIRT1 inhibitor, MEK inhibitor, or by mating the AC5 KO with MnSOD hetero KO mice, confirming the role of SIRT1, MEK, and oxidative stress mechanisms. The Caenorhabditis elegans worm AC5 ortholog, acy-3 by RNAi, also improved fitness, mitochondrial function, antioxidant defense, and lifespan, attesting to the evolutionary conservation of this pathway. Thus, decreasing sympathetic signaling through loss of AC5 is not only a mechanism to improve exercise performance, but is also a mechanism to improve healthful aging, as exercise also protects against diabetes, obesity, and cardiovascular disease, which all limit healthful aging.

과당음료 투여가 최대운동부하시 운동수행력, 심폐기능, 젖산 및 염증반응에 미치는 영향

The use of fructose-containing sports beverage drinks has increased in recent years, especially at sport events, because of their reported ergogenic effects. However, the ingestion of low to moderate doses of caffeinated energy drinks has been associated with adverse side effects such as insomnia or increased nervousness. The purpose of this study was to investigate the effects of fructose beverage supplementation on cardiopulmonary function, blood lactate levels, and inflammatory reactions. We recruited 8 young adult subjects from D university and measured their cardiopulmonary functions before and after supplementation with sports beverage drinks. We also measured blood lactate and inflammatory reactions after a 20 min recovery period. Exercise time, maximal oxygen uptake (V0 2 max), and AT HRmax were significantly increased (p 2 max RER, AT V0 2 max, and maximum heart rate (HRmax). Lactate levels also significantly decreased after 20 min recovery with sports beverage supplementation. Sports beverage supplementation therefore may enhance maximal V02max and increase the exercise duration time. These drinks may also be helpful in promoting rapid recovery of fatigue variables and increasing exercise performance time.

Activation of AMPK and its Impact on Exercise Capacity.

Activation of the adenosine monophosphate (AMP)-activated kinase (AMPK) contributes to beneficial effects such as improvement of the hyperglycemic state in diabetes as well as reduction of obesity and inflammatory processes. Furthermore, stimulation of AMPK activity has been associated with increased exercise capacity. A study published in 2008, directly before the Olympic Games in Beijing, showed that the AMPK activator AICAR (5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide) increased the running capacity of mice without any training and thus, prompted the World Anti-Doping Agency (WADA) to include certain AMPK activators in the list of forbidden drugs. This raises the question as to whether all AMPK activators should be considered for registration or whether the increase in exercise performance is only associated with specific AMPK-activating substances. In this review, we intend to shed light on currently published AMPK-activating drugs, their working mechanisms, and their impact on body fitness.

Dietary Inorganic Nitrate and Acute Increases in Exercise Performance in Peripheral Arterial Disease (PAD)

Dietary Inorganic Nitrate and Acute Increases in Exercise Performance in Peripheral Arterial Disease (PAD)

α‐actinin‐3 deficiency is associated with increased exercise performance and training‐induced changes in mitochondrial respiration in humans

Deficiency of α‐actinin‐3 protein, as a consequence of the ACTN3 577XX genotype, has been shown to influence exercise performance. However, little is known about how α‐actinin‐3 deficiency influences training response in humans.AimTo investigate the influence of α‐actinin‐3 deficiency on performance outcomes and mitochondrial respiration following High‐Intensity Interval Training (HIIT).MethodsTwelve moderately‐trained Caucasian males (7 XX and 5 RR) were recruited, with matched body mass index (BMI). Following baseline tests, participants underwent 4 weeks of HIIT. 20km time‐trial (20km TT), and graded exercise test (GXT), to assess peak oxygen uptake (VO2Peak) and the Lactate threshold (LT), were performed pre and post training. A muscle biopsy was taken pre and post training, and analysed for in situ mitochondrial respiration.ResultsThe XX participants had higher VO2peak at baseline (50.05 vs 44.07 ml kg‐1 min‐1 for XX and RR). Moreover, the XX participants finished the 20 km TT faster (40 min 20 s vs 42 min 25 s). Following 4 weeks of HIIT, the XX participants showed a greater increase in maximal mitochondrial respiration (Vmax) (XX = 19.20 vs RR = 8.24 pmol s−1 mg−1 ww). imageFurthermore, the XX participants showed higher increase in LT (XX = 26.1 W vs RR=23.1 W), and VO2peak (XX = 3.10 vs RR = 2.80 ml kg‐1 min‐1).ConclusionThese preliminary results indicate that α‐actinin‐3 deficient individuals had better endurance capacity, which could be resulted from higher maximal mitochondrial respiration after training.

Effective Danio rerio Endurance Exercise Training Model

Exercise training as a stimulus for increased exercise performance is well studied in humans. Scientists also have used model organisms: cats, rodents, and famously; shrimp, to study exercise adaptations. The use of zebrafish (Danio rerio) as a model to study exercise is an underutilized resource, despite their lower cost, maintenance, and space requirements. Developing zebrafish as a model to study exercise would allow experimentation into a widely used vertebrate model. In order for zebrafish to be a model for exercise training studies the training dose needed to induce performance increases must be determined. Therefore, the purpose of this research was to establish a minimum exercise training dose needed to increase swimming performance. Adult zebrafish were tested for their pre‐training maximum absolute sustained swimming speed (Ucrit). The fish were then swim trained during 14 sessions over the course of 3 weeks. Each training session was 120 minutes long, with not more than 3 consecutive days of training in a row. During the first training session each fish trained against a 50 cm/s water flow rate for the first 1.5 hours, followed by 60cm/s water flow rate for the last 15 minutes. Subsequently, the duration of 50 cm/s swim speed was decreased and the duration of the 60 cm/s speed increased progressively over the course of the 3 week training period. The fish rested for a day following the last training bout and then post training Ucrit was measured. The average pre‐exercise training value was 56.8 cm/s. The average post‐exercise training Ucrit value was 63.4 cm/s. Post training Ucrit was 12% higher than pre‐training values (p&lt;0.003). In conclusion, exercise training can increase endurance swimming ability in zebrafish, supporting the viability of using zebrafish as an animal model for studies of exercise training.

The small-molecule fast skeletal troponin activator, CK-2127107, improves exercise tolerance in a rat model of heart failure.

Heart failure-mediated skeletal myopathy, which is characterized by muscle atrophy and muscle metabolism dysfunction, often manifests as dyspnea and limb muscle fatigue. We have previously demonstrated that increasing Ca(2+) sensitivity of the sarcomere by a small-molecule fast skeletal troponin activator improves skeletal muscle force and exercise performance in healthy rats and models of neuromuscular disease. The objective of this study was to investigate the effect of a novel fast skeletal troponin activator, CK-2127107 (2-aminoalkyl-5-N-heteroarylpyrimidine), on skeletal muscle function and exercise performance in rats exhibiting heart failure-mediated skeletal myopathy. Rats underwent a left anterior descending coronary artery ligation, resulting in myocardial infarction and a progressive decline in cardiac function [left anterior descending coronary artery heart failure (LAD-HF)]. Compared with sham-operated control rats, LAD-HF rat hindlimb and diaphragm muscles exhibited significant muscle atrophy. Fatigability was increased during repeated in situ isokinetic plantar flexor muscle contractions. CK-2127107 produced a leftward shift in the force-Ca(2+) relationship of skinned, single diaphragm, and extensor digitorum longus fibers. Exercise performance, which was assessed by rotarod running, was lower in vehicle-treated LAD-HF rats than in sham controls (116 ± 22 versus 193 ± 31 seconds, respectively; mean ± S.E.M.; P = 0.04). In the LAD-HF rats, a single oral dose of CK-2127107 (10 mg/kg p.o.) increased running time compared with vehicle treatment (283 ± 47 versus 116 ± 22 seconds; P = 0.0004). In summary, CK-2127107 substantially increases exercise performance in this heart failure model, suggesting that modulation of skeletal muscle function by a fast skeletal troponin activator may be a useful therapeutic in heart failure-associated exercise intolerance.

Effect of inspiratory muscle warm-up on submaximal rowing performance.

Performing inspiratory muscle warm-up might increase exercise performance. The aim of this study was to investigate the impact of inspiratory muscle warm-up to submaximal rowing performance and to find if there is an effect on lactic acid accumulation and breathing parameters. Ten competitive male rowers aged between 19 and 27 years (age, 23.1 ± 3.8 years; height, 188.1 ± 6.3 cm; body mass, 85.6 ± 6.6 kg) were tested 3 times. During the first visit, maximal inspiratory pressure (MIP) assessment and the incremental rowing test were performed to measure maximal oxygen consumption and maximal aerobic power (Pamax). A submaximal intensity (90% Pamax) rowing test was performed twice with the standard rowing warm-up as test 1 and with the standard rowing warm-up and specific inspiratory muscle warm-up as test 2. During the 2 experimental tests, distance, duration, heart rate, breathing frequency, ventilation, peak oxygen consumption, and blood lactate concentration were measured. The only value that showed a significant difference between the test 1 and test 2 was breathing frequency (52.2 ± 6.8 vs. 53.1 ± 6.8, respectively). Heart rate and ventilation showed a tendency to decrease and increase, respectively, after the inspiratory muscle warm-up (p < 0.1). Despite some changes in respiratory parameters, the use of 40% MIP intensity warm-up is not suggested if the mean intensity of the competition is at submaximal level (at approximately 90% maximal oxygen consumption). In conclusion, the warm-up protocol of the respiratory muscles used in this study does not have a significant influence on submaximal endurance performance in highly trained male rowers.