Caffeine’s Beneficial Effect on Maximal Voluntary Strength and Activation in Uninjured but Not Injured Muscle

2008 ◽  
Vol 18 (6) ◽  
pp. 639-652 ◽  
Author(s):  
Nicole D. Park ◽  
Robert D. Maresca ◽  
Kimberly I. McKibans ◽  
D. Reid Morgan ◽  
Timothy S. Allen ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Muscle Activation ◽  
Eccentric Contraction ◽  
Knee Extensors ◽  
Double Blind ◽  
Maximal Voluntary Isometric Contraction ◽  
Caffeine Ingestion ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Before And After

The study’s objective was to determine whether orally ingested caffeine could help overcome excitation-contraction-coupling failure, which has been suggested to explain part of the strength loss associated with eccentric-contraction-induced muscle injury. A sample of 13 college students (4 men and 9 women) was used in a double-blind, repeated-measures experimental design. Each participant performed 2 experimental trials, 1 with each leg, with each trial lasting 4 consecutive days. On a given day, each participant was randomly assigned to ingest a capsule containing 6 mg/kg of either caffeine or flour (placebo). On the day of and the first 2 days after a bout of 50 injurious eccentric contractions done by the knee extensors, the interpolated-twitch technique was used to assess electrically evoked strength, maximal voluntary isometric contraction (MVIC) strength, and percent muscle activation during MVIC both before and after capsule ingestion. These variables were also measured before and after capsule ingestion the day before the eccentric-contraction bout—when the muscle was uninjured. In injured muscle, caffeine had no effect on any variable. In uninjured muscle, caffeine also had no effect on electrically evoked strength but increased MVIC strength by 10.4% compared with placebo (p = .00002), and this was attributed to an increase in muscle activation (6.2%; p = .01). In conclusion, the data provide no evidence that caffeine ingestion can help overcome excitation-contraction-coupling failure, if it exists, in injured human muscle. The data do indicate that caffeine ingestion can increase MVIC strength and activation in uninjured muscle but not in injured muscle.

scholarly journals Beta alanine supplementation effects on metabolic contribution and swimming performance

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Matheus Silva Norberto ◽  
Ricardo Augusto Barbieri ◽  
Danilo Rodrigues Bertucci ◽  
Ronaldo Bucken Gobbi ◽  
Eduardo Zapaterra Campos ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Energy Demand ◽  
Swimming Performance ◽  
Controlled Study ◽  
Double Blind ◽  
Repeated Measures Anova ◽  
Beta Alanine ◽  
Before And After ◽  
The Difference ◽  
And Performance

Abstract Background Investigations of β-alanine supplementation shows effects on metabolic (aerobic and anaerobic) participation and performance on swimming by a possible blood acidosis buffering. Considering this background, the objective of the present study was to analyze the effects of β-alanine supplementation on metabolic contribution and performance during 400-m swim. Methods Thirteen competitive swimmers underwent a 6-week, double-blind placebo-controlled study, ingesting 4.8 g.day− 1 of β-alanine or placebo. Before and after the supplementation period, the total anaerobic contribution (TAn) and 30-s all-out tethered swimming effort (30TS) were assessed. Anaerobic alactic (AnAl) and lactic energy (AnLa) was assumed as the fast component of excess post-exercise oxygen consumption and net blood lactate accumulation during exercise (∆[La−]), respectively. Aerobic contribution (Aer) was determined by the difference between total energy demand and TAn. In addition to conventional statistical analysis (Repeated measures ANOVA; p > 0.05), a Bayesian repeated measures ANOVA was used to evidence the effect probability (BFincl). Results No differences and effects were found between groups, indicating no supplementation effects. Repeated measures ANOVA, with confirmation of effect, was indicate reduce in ∆Lactate (p: 0.001; BFincl: 25.02); absolute AnLa (p: 0.002; BFincl: 12.61), fatigue index (p > 0.001; BFincl: 63.25) and total anaerobic participation (p: 0.008; BFincl: 4.89). Conclusions Thus, the results demonstrated that all changes presented were evidenced as a result of exposure to the training period and β-alanine supplementation doesn’t affect metabolic contribution and performance during 400-m freestyle.

scholarly journals A Combination of Amino Acids and Caffeine Enhances Sprint Running Capacity in a Hot, Hypoxic Environment

2016 ◽  
Vol 26 (1) ◽  
pp. 33-45 ◽  
Author(s):  
Tom R. Eaton ◽  
Aaron Potter ◽  
François Billaut ◽  
Derek Panchuk ◽  
David B. Pyne ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Near Infrared ◽  
Cerebral Oxygenation ◽  
Team Sport ◽  
Exercise Session ◽  
Emg Activity ◽  
Double Blind ◽  
Caffeine Ingestion ◽  
Sprint Running ◽  
Hypoxic Environment

Heat and hypoxia exacerbate central nervous system (CNS) fatigue. We therefore investigated whether essential amino acid (EAA) and caffeine ingestion attenuates CNS fatigue in a simulated team sport–specific running protocol in a hot, hypoxic environment. Subelite male team sport athletes (n = 8) performed a repeat sprint running protocol on a nonmotorized treadmill in an extreme environment on 4 separate occasions. Participants ingested one of four supplements: a double placebo, 3 mg.kg-1 body mass of caffeine + placebo, 2 × 7 g EAA (Musashi Create)+placebo, or caffeine + EAA before each exercise session using a randomized, double-blind crossover design. Electromyography (EMG) activity and quadriceps evoked responses to magnetic stimulation were assessed from the dominant leg at preexercise, halftime, and postexercise. Central activation ratio (CAR) was used to quantify completeness of quadriceps activation. Oxygenation of the prefrontal cortex was measured via near-infrared spectroscopy. Mean sprint work was higher (M = 174 J, 95% CI [23, 324], p < .05, d = 0.30; effect size, likely beneficial) in the caffeine + EAA condition versus EAAs alone. The decline in EMG activity was less (M = 13%, 95% CI [0, 26]; p < .01, d = 0.58, likely beneficial) in caffeine + EAA versus EAA alone. Similarly, the pre- to postexercise decrement in CAR was significantly less (M = −2.7%, 95% CI [0.4, 5.4]; p < .05, d = 0.50, likely beneficial) when caffeine + EAA were ingested compared with placebo. Cerebral oxygenation was lower (M = −5.6%, 95% CI [1.0, 10.1]; p < .01, d = 0.60, very likely beneficial) in the caffeine + EAA condition compared with LNAA alone. Coingestion of caffeine and EAA appears to maintain muscle activation and central drive, with a small improvement in running performance.

Effect of caffeine on skeletal muscle function before and after fatigue

1983 ◽  
Vol 54 (5) ◽  
pp. 1303-1305 ◽  
Author(s):  
J. M. Lopes ◽  
M. Aubier ◽  
J. Jardim ◽  
J. V. Aranda ◽  
P. T. Macklem
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Relaxation Rate ◽  
Voluntary Contraction ◽  
Contractile Properties ◽  
Double Blind ◽  
Caffeine Ingestion ◽  
Muscle Contractile Properties ◽  
Before And After ◽  
Muscle Contractile

We studied the effect of caffeine on voluntary and electrically stimulated contractions of the adductor pollicis muscle in five adult volunteers. Caffeine (500 mg) was administered orally in a double-blind fashion. Electrical stimulation of the ulnar nerve was performed at 10, 20, 30, 50, and 100 Hz before and after a sustained voluntary contraction held at 50% of the maximal voluntary contraction (MVC). A brief tetanus at 30 Hz was also performed to calculate relaxation rate in the fresh muscle. Contractile properties, relaxation rate, and endurance were then assessed after caffeine and placebo, as well as the response of the fatigued muscle to different frequencies of stimulation. There was no difference in the maximal tension obtained with electrical stimulation (T100) or in the MVC between placebo and caffeine. The tensions developed with electrical stimulation at lower frequencies increased significantly with caffeine ingestion, shifting the frequency-force curve to the left, both before and after fatigue. Mean plasma caffeine concentration associated with these responses was 12.2 +/- 4.9 mg/l. We conclude that caffeine has a direct effect on skeletal muscle contractile properties both before and after fatigue as demonstrated by electrical stimulation.

scholarly journals Muscle Coactivation Before and After the Impact Phase of Running Following Isokinetic Fatigue

2011 ◽  
Vol 46 (1) ◽  
pp. 11-19 ◽  
Author(s):  
Eleftherios Kellis ◽  
Andreas Zafeiridis ◽  
Ioannis G. Amiridis
Keyword(s):  
Muscle Activation ◽  
Biceps Femoris ◽  
Knee Extension ◽  
Knee Extensors ◽  
Training Experience ◽  
Cross Sectional ◽  
Muscle Activation Patterns ◽  
Strength Capacity ◽  
Before And After ◽  
The Impact

Abstract Context: The effects of fatigue on impact loading during running are unclear, with some authors reporting increased impact forces and others reporting decreased forces. Objective: To examine the effects of isokinetic fatigue on muscle cocontraction ratios about the knee and ankle during running. Design: Cross-sectional study. Setting: Neuromechanics laboratory. Patients or Other Participants: Female middle-distance runners (age  =  21.3 ± 1.93 years) with at least 5 years of training experience. Intervention(s): Participants ran on the treadmill at 3.61 m/s before and immediately after the fatigue protocol, which consisted of consecutive, concentric knee extension-flexion at 120°/s until they could no longer produce 30% of the maximum knee-extension moment achieved in the familiarization session for 3 consecutive repetitions. Main Outcome Measure(s): Electromyographic (EMG) amplitude of the vastus medialis (VM), biceps femoris (BF), gastrocnemius (GAS), and tibialis anterior (TA) was recorded using surface electrodes. Agonist∶antagonist EMG ratios for the knee (VM∶BF) and ankle (GAS∶TA) were calculated for the preactivation (PR), initial loading response (LR1), and late loading response (LR2) phases of running. Hip-, knee-, and ankle-joint angular displacements at initial foot contact were obtained from 3-dimensional kinematic tracings. Results: Fatigue did not alter the VM∶BF EMG ratio during the PR phase (P &gt; .05), but it increased the ratio during the LR1 phase (P &lt; .05). The GAS∶TA EMG ratio increased during the LR1 phase after fatigue (P &lt; .05) but remained unchanged during the PR and LR2 phrases (P &gt; .05). Conclusions: The increased agonist EMG activation, coupled with reduced antagonist EMG activation after impact, indicates that the acute decrease in muscle strength capacity of the knee extensors and flexors results in altered muscle-activation patterns about the knee and ankle before and after foot impact.

scholarly journals Muscle Activation and Perceived Loading During Rehabilitation Exercises: Comparison of Dumbbells and Elastic Resistance

2010 ◽  
Vol 90 (4) ◽  
pp. 538-549 ◽  
Author(s):  
Lars L. Andersen ◽  
Christoffer H. Andersen ◽  
Ole S. Mortensen ◽  
Otto M. Poulsen ◽  
Inger Birthe T. Bjørnlund ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Muscle Activation ◽  
Musculoskeletal Diseases ◽  
External Rotation ◽  
Emg Activity ◽  
Absolute Maximum ◽  
Maximal Voluntary Isometric Contraction ◽  
Emg Amplitude ◽  
Elastic Resistance ◽  
Resistance Exercises

BackgroundHigh-intensity resistance training plays an essential role in the prevention and rehabilitation of musculoskeletal injuries and disorders. Although resistance exercises with heavy weights yield high levels of muscle activation, the efficacy of more user-friendly forms of exercise needs to be examined.ObjectiveThe aim of this study was to investigate muscle activation and perceived loading during upper-extremity resistance exercises with dumbbells compared with elastic tubing.DesignA single-group, repeated-measures study design was used.SettingExercise evaluation was conducted in a laboratory setting.ParticipantsSixteen female workers (aged 26–55 years) without serious musculoskeletal diseases and with a mean neck and shoulder pain intensity of 7.8 on a 100-mm visual analog scale participated in the study.MeasurementsElectromyographic (EMG) activity was measured in 5 selected muscles during the exercises of lateral raise, wrist extension, and shoulder external rotation during graded loadings with dumbbells (2–7.5 kg) and elastic tubing (Thera-Band, red to silver resistance). The order of exercises and loadings was randomized for each individual. Electromyographic amplitude was normalized to the absolute maximum EMG amplitude obtained during maximal voluntary isometric contraction and exercise testing. Immediately after each set of exercise, the Borg CR10 scale was used to rate perceived loading during the exercise.ResultsResistance exercise with dumbbells as well as elastic tubing showed increasing EMG amplitude and perceived loading with increasing resistance. At the individually maximal level of resistance for each exercise—defined as the 3 repetitions maximum—normalized EMG activity of the prime muscles was not significantly different between dumbbells (59%–87%) and elastic tubing (64%–86%). Perceived loading was moderately to very strongly related to normalized EMG activity (r=.59–.92).LimitationsThe results of this study apply only for exercises performed in a controlled manner (ie, without sudden jerks or high acceleration).ConclusionsComparably high levels of muscle activation were obtained during resistance exercises with dumbbells and elastic tubing, indicating that therapists can choose either type in clinical practice. The Borg CR10 can be a useful aid in estimating intensity of individual rehabilitation protocols.

scholarly journals The Effect of AcuteRhodiola roseaIngestion on Exercise Heart Rate, Substrate Utilisation, Mood State, and Perceptions of Exertion, Arousal, and Pleasure/Displeasure in Active Men

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Michael J. Duncan ◽  
Neil D. Clarke
Keyword(s):  
Heart Rate ◽  
Energy Expenditure ◽  
Repeated Measures ◽  
Mood State ◽  
Cycling Performance ◽  
Exercise Heart Rate ◽  
Double Blind ◽  
Substrate Utilisation ◽  
Repeated Measures Analysis ◽  
Before And After

The aim of this study was to examine the effect of acuteRhodiola rosea(R. rosea) ingestion on substrate utilisation, mood state, RPE, and exercise affect. Ten males (mean age ± S.D. = 26 ± 6 years) completed two 30-minute cycling trials at an intensity of 70% ofV˙O2max⁡following ingestion of either 3 mg·kg−1body mass ofR. roseaor placebo using a double-blind, crossover design. During exercise, heart rate and RPE were recorded. Participants completed measures of mood state and exercise affect before and after exercise. Expired air samples were taken during exercise to determine substrate utilisation. Repeated measures analysis of variance indicated that RPE was significantly lower at 30 minutes into exercise versus placebo (P=0.003). Perceptions of arousal (P=0.05) and pleasure were significantly higher after exercise withR. roseacompared to placebo (P=0.003). Mood state scores for vigor were also higher inR. roseacondition compared to placebo (P=0.008). There were no significant differences in energy expenditure, carbohydrate, or fat oxidation between conditions (P>0.05). Ingestion ofR. roseafavourably influenced RPE and exercise affect without changes in energy expenditure or substrate utilization during 30-minute submaximal cycling performance.

scholarly journals Quadriceps Function After Exercise in Patients with Anterior Cruciate Ligament–Reconstructed Knees Wearing Knee Braces

2011 ◽  
Vol 46 (6) ◽  
pp. 615-620 ◽  
Author(s):  
Alexis G. Davis ◽  
Brian G. Pietrosimone ◽  
Christopher D. Ingersoll ◽  
Kelli Pugh ◽  
Joseph M. Hart
Keyword(s):  
Anterior Cruciate Ligament ◽  
Aerobic Exercise ◽  
Muscle Activation ◽  
Cruciate Ligament ◽  
Knee Brace ◽  
Maximal Voluntary Isometric Contraction ◽  
Before And After ◽  
Knee Braces ◽  
Anterior Cruciate ◽  
Quadriceps Function

Context: Knee braces and neoprene sleeves are commonly worn by people with anterior cruciate ligament reconstructions (ACLRs) during athletic activity. How knee braces and sleeves affect muscle activation in people with ACLRs is unclear.Purpose: To determine the effects of knee braces and neoprene knee sleeves on the quadriceps central activation ratio (CAR) before and after aerobic exercise in people with ACLRs.Design: Crossover study.Patients or Other Participants: Fourteen people with a history of ACLR (9 women, 5 men: age = 23.61 ± 4.44 years, height = 174.09 ± 9.82 cm, mass = 75.35 ± 17.48 kg, months since ACLR = 40.62 ± 20.41).Intervention(s): During each of 3 sessions, participants performed a standardized aerobic exercise protocol on a treadmill. The independent variables were condition (brace, sleeve, or control) and time (baseline, pre-exercise with brace, postexercise with brace, postexercise without brace).Main Outcome Measure(s): Normalized torque measured during a maximal voluntary isometric contraction (TMVIC) and CAR were measured by a blinded assessor using the superimposed burst technique. The CAR was expressed as a percentage of full muscle activation. The quadriceps CAR and TMVIC were measured 4 times during each session: baseline, pre-exercise with brace, postexercise with brace, and postexercise without brace.Results: Immediately after the application of the knee brace, TMVIC decreased (P = .01), but no differences between bracing conditions were observed. We noted reduced TMVIC and CAR (P &lt; .001) after exercise, both with and without the brace. No differences were seen between bracing conditions after aerobic exercise.Conclusions: The decrease in TMVIC immediately after brace application was not accompanied by differences between bracing conditions. Wearing a knee brace or neoprene sleeve did not seem to affect the deterioration of quadriceps function after aerobic exercise.

Effects of Fatigue on Voluntary Electromechanical and Relaxation Electromechanical Delay

2017 ◽  
Vol 38 (10) ◽  
pp. 763-769 ◽  
Author(s):  
Cory Smith ◽  
Terry Housh ◽  
Ethan Hill ◽  
Joshua Keller ◽  
Glen Johnson ◽  
...  
Keyword(s):  
Vastus Lateralis ◽  
Force Production ◽  
Elastic Component ◽  
Electromechanical Delay ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Series Elastic Component ◽  
Before And After ◽  
Electromyographic Signal ◽  
Series Elastic

AbstractThe purposes of the present study were to examine: 1) the effects of fatigue on electromechanical delay from the onsets of the electromyographic signal to force production (EMDE-F), the onsets of the electromyographic to mechanomyographic signals (EMDE-M), the onsets of the mechanomyographic signal to force production (EMDM-F), as well as the cessations of the electromyographic to force production (R-EMDE-F), cessation of the electromyographic to mechanomyographic signals (R-EMDE-M), and cessations of the mechanomyographic signal to force production (R-EMDM-F); and 2) the relative contributions from EMDE-M and EMDM-F to EMDE-F as well as R-EMDE-M and R-EMDM-F to R-EMDE-F from the vastus lateralis in non-fatigued and fatigued states. The values EMDE-F, EMDE-M, EMDM-F, R-EMDE-F, R-EMDE-M and R-EMDM-F were calculated during maximal voluntary isometric contractions, before and after 70% 1-repetition maximum leg extensions to failure. There were significant pretest to posttest increases in EMDE-F (73%;p<0.01), EMDE-M (99%;p<0.01), EMDM-F (60%;p<0.01), R-EMDE-F (101%;p<0.01) and R-EMDM-F (368%;p<0.01), but no significant change in R-EMDE-M (25%;p=0.46). Fatigue-induced increase in EMDE-F indicated excitation-contraction coupling failure (EMDE-M) and increases in the compliance of the series elastic component (EMDM-F). Increases in R-EMDE-F were due to increases in relaxation time for the series elastic component (R-EMDM-F), but not changes in the reversal of excitation-contraction coupling (R-EMDE-M).

Caffeinated Sports Drink: Ergogenic Effects and Possible Mechanisms

2007 ◽  
Vol 17 (1) ◽  
pp. 35-55 ◽  
Author(s):  
Kirk J. Cureton ◽  
Gordon L. Warren ◽  
Mindy L. Millard-Stafford ◽  
Jonathan E. Wingo ◽  
Jennifer Trilk ◽  
...  
Keyword(s):  
Perceived Exertion ◽  
Strength Loss ◽  
The Other ◽  
Knee Extensors ◽  
Double Blind ◽  
Sports Drink ◽  
Warm Environment ◽  
Interpolated Twitch Technique ◽  
Ergogenic Effects ◽  
Before And After

This double-blind experiment examined the effects of a caffeinated sports drink during prolonged cycling in a warm environment. Sixteen highly trained cyclists completed 3 trials: placebo, carbohydrate-electrolyte sports drink (CES), and caffeinated sports drink (CES+CAF). Subjects cycled for 135 min, alternating between 60% and 75% VO2max every 15 min for the first 120 min, followed by a 15-min performance ride. Maximal voluntary (MVC) and electrically evoked contractile properties of the knee extensors were measured before and after cycling. Work completed during the performance ride was 15–23% greater for CES+CAF than for the other beverages. Ratings of perceived exertion were lower with CES+CAF than with placebo and CES. After cycling, the MVC strength loss was two-thirds less for CES+CAF than for the other beverages (5% vs. 15%). Data from the interpolated-twitch technique indicated that attenuated strength loss with CES+CAF was explained by reduced intrinsic muscle fatigue.

Effects of caffeine on neuromuscular function

1999 ◽  
Vol 87 (2) ◽  
pp. 801-808 ◽  
Author(s):  
J. M. Kalmar ◽  
E. Cafarelli
Keyword(s):  
Repeated Measures ◽  
Isometric Force ◽  
Neuromuscular Function ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Knee Extensors ◽  
Double Blind ◽  
Twitch Interpolation ◽  
Motor Unit Firing ◽  
The Right

This double-blind, repeated-measures study examined the effects of caffeine on neuromuscular function. Eleven male volunteers [22.3 ± 2.4 (SD) yr] came to the laboratory for control, placebo, and caffeine (6 mg/kg dose) trials. Each trial consisted of 10 × 1-ms stimulation of the tibial nerve to elicit maximal H reflexes of the soleus, four attempts at a maximal voluntary contraction (MVC) of the right knee extensors, six brief submaximal contractions, and a 50% MVC held to fatigue. Isometric force and surface electromyographic signals were recorded continuously. The degree of maximal voluntary activation was assessed with the twitch-interpolation technique. Single-unit recordings were made with tungsten microelectrodes during the submaximal contractions. Voluntary activation at MVC increased by 3.50 ± 1.01 (SE) % ( P < 0.01), but there was no change in H-reflex amplitude, suggesting that caffeine increases maximal voluntary activation at a supraspinal level. Neither the force-EMG relationship nor motor unit firing rates were altered by caffeine. Subjects were able to hold a 50% MVC for an average of 66.1 s in the absence of caffeine. Time to fatigue (Tlim) increased by 25.80 ± 16.06% after caffeine administration ( P < 0.05). There was no significant change in Tlim from pretest to posttest in the control or placebo trials. The increase in Tlim was associated with an attenuated decline in twitch amplitude, which would suggest that the mechanism is, at least in part, peripheral.

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