Wingate performance and surface EMG frequency variables are not affected by caffeine ingestion

2006 ◽  
Vol 31 (5) ◽  
pp. 597-603 ◽  
Author(s):  
Felicia Greer ◽  
Jacobo Morales ◽  
Michael Coles
Keyword(s):  
Body Mass ◽  
Power Output ◽  
High Intensity ◽  
Repeated Measures ◽  
Surface Emg ◽  
Knee Extensors ◽  
Caffeine Ingestion ◽  
Emg Signal ◽  
Significant Difference ◽  
Percent Decline

The ergogenic effect of caffeine and its mechanism of action on short-term, high-intensity exercise are controversial. One proposed mechanism is caffeine’s stimulatory effect on the central nervous system and thus, motor-unit excitation. The latter is non-invasively determined from surface electromyographic signal (EMG) frequency measures. The purpose of this study was to determine if power output and surface EMG frequency variables during high-intensity cycling were altered following caffeine ingestion. Eighteen recreationally active college males (mean ± SD age, 21.5 ± 1.8 y; height, 181.8 ± 0.5 cm; body mass, 84.7 ± 11.4 kg) performed the Wingate test (WG) after ingestion of gelatin capsules containing either placebo (PL; dextrose) or caffeine (CAFF; 5 mg/kg body mass). The trials were separated by 1 week and subjects were asked to withdraw from all caffeine-containing products for 48 h before each trial. From the resulting power–time records, peak power (PP; highest power output in 5 s), minimum power (MP; lowest power output in 5 s), and the percent decline in power (Pd) were calculated. Surface EMG records of the right vastus lateralis (VL) and the gastrocnemius (GA) muscles corresponding to the PP and MP periods were collected and used to determine the integrated electromyogram (IEMG), the mean (MNPF), and the median (MDPF) of the signal’s power spectrum. A 2-way repeated measures analysis of variance (ANOVA) (treatment × time) was conducted to determine the effect of caffeine on these variables across levels of time. Caffeine ingestion had no effect on PP (PL, 1049 ± 192 W; CAFF, 1098 ± 198 W), MP (PL, 762 ± 104 W; CAFF, 802 ± 124 W), or the Pd (PL, 47% ± 8.9%; CAFF, 48.2% ± 7.3%) compared with the placebo. For both muscles, MNPF and MDPF diminished significantly (p < 0.001) across time and to a similar degree in both the CAFF and PL trials. Regardless of muscle, CAFF had no effect on the percent change in IEMG from the first 5 s to the last 5 s. For both treatments, the GA displayed a significantly (p < 0.05) greater pre vs. post percent decline in the EMG signal amplitude compared with the VL. These results indicate that caffeine does not impact power output during a 30 s high-intensity cycling bout. Furthermore, these data suggest that caffeine does not impact the neuromuscular drive as indicated by the similar IEMG scores between treatments. Similarly, caffeine does not seem to impact the frequency content of the surface EMG signal and thus the nature of recruited motor units before and after the expression of fatigue. The lack of decline in the IEMG in the VL despite the decline in power output over the course of the WG suggests a peripheral as opposed to a neural mechanism of fatigue in this muscle. The significant difference in the pre vs. post percent decline in the GA IEMG score further supports this notion. The pre vs. post decline in the IEMG noted in the GA may suggest a fatigue-triggered change in pedaling mechanics that may promote dominance of knee extensors with less reliance on plantar flexors.

scholarly journals Surface EMG signal normalisation and filtering improves sensitivity of equine gait analysis

2019 ◽  
Vol 15 (3) ◽  
pp. 173-185 ◽  
Author(s):  
L. St. George ◽  
S.H. Roy ◽  
J. Richards ◽  
J. Sinclair ◽  
S.J. Hobbs
Keyword(s):  
Repeated Measures ◽  
Low Frequency ◽  
Biceps Femoris ◽  
Surface Emg ◽  
Frequency Noise ◽  
Vertical Loading ◽  
Stifle Joint ◽  
Emg Signal ◽  
Stride Duration ◽  
High Pass

Low-frequency noise attenuation and normalisation are fundamental signal processing (SP) methods for surface electromyography (sEMG), but are absent, or not consistently applied, in equine biomechanics. The purpose of this study was to examine the effect of different band-pass filtering and normalisation conventions on sensitivity for identifying differences in sEMG amplitude-related measures, calculated from leading (LdH) and trailing hindlimb (TrH) during canter, where between-limb differences in vertical loading are known. sEMG and 3D-kinematic data were collected from the right Biceps Femoris in 10 horses during both canter leads. Peak hip and stifle joint angle and angular velocity were calculated during stance to verify between-limb biomechanical differences. Four SP methods, with and without normalisation and high-pass filtering, were applied to raw sEMG data. Methods 1 (M1) to 4 (M4) included DC-offset removal and full-wave rectification. Method 2 (M2) included additional normalisation relative to maximum sEMG across all strides. Method 3 (M3) included additional high-pass filtering (Butterworth 4th order, 40 Hz cut-off), for artefact attenuation. M4 included the addition of high-pass filtering and normalisation. Integrated EMG (iEMG) and average rectified value (ARV) were calculated using processed sEMG data from M1 – M4, with stride duration as the temporal domain. sEMG parameters, within M1 – M4, and kinematic parameters were grouped by LdH and TrH and compared using repeated measures ANOVA. Significant between-limb differences for hip and stifle joint kinematics were found, indicating functional differences in hindlimb movement. M2 and M4, revealed significantly greater iEMG and ARV for LdH than TrH (P<0.01), with M4 producing the lowest P-values and largest effect sizes. Significant between-limb differences in sEMG parameters were not observed with M1 and M3. The results indicate that equine sEMG SP should include normalisation and high-pass filtering to improve sensitivity for identifying differences in muscle function associated with biomechanical changes during equine gait.

The acute effects of a low and high dose of oral l-arginine supplementation in young active males at rest

2011 ◽  
Vol 36 (3) ◽  
pp. 405-411 ◽  
Author(s):  
Scott C. Forbes ◽  
Gordon J. Bell
Keyword(s):  
Body Mass ◽  
Repeated Measures ◽  
Plasma Concentrations ◽  
Insulin Response ◽  
High Dose ◽  
Placebo Condition ◽  
Double Blind ◽  
Physically Active ◽  
Significant Difference ◽  
Arginine Supplementation

l-arginine (2-amino-5-guanidinovaleric acid) is a conditionally essential amino acid. Intravenous (IV) administration of l-arginine invokes a large metabolic (nitrate/nitrite (NOx)) and hormonal (growth hormone (GH), insulin-like growth factor 1 (IGF-1), and insulin) response; however, research examining oral l-arginine supplementation is conflicting, potentially owing to dose. The purpose of this study was examine a low and high dose of oral l-arginine on blood l-arginine, NOx, GH, IGF-1, and insulin response. Fourteen physically active males (age: 25 ± 5 years; weight: 78.0 ± 8.5 kg; height: 179.4 ± 4.7 cm) volunteered to be in a randomized, double-blind, repeated-measures study. Following an overnight fast, an IV catheter was placed in a forearm vein and a resting blood sample was drawn at ∼0800 hours. Each subject was then provided 1 of 3 treatment conditions (placebo, low (0.075 g·kg–1 of body mass), or high (0.15 g·kg–1 of body mass of l-arginine)). Blood samples were drawn at 30, 60, 90, 120, and 180 min after consumption. l-arginine plasma concentrations significantly increased (p < 0.001) to a similar level at any time point in both the low- and high-dose conditions; there was no change over time in the placebo condition. There was no significant difference between conditions for NOx, GH, IGF-1, or insulin. Based on these findings, a low dose of l-arginine was just as effective at increasing plasma l-arginine concentrations as a high dose; however, neither dose was able to promote a significant increase in NOx, GH, IGF-1, or insulin at rest.

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.

N-acetylcysteine alters substrate metabolism during high-intensity cycle exercise in well-trained humans

2013 ◽  
Vol 38 (12) ◽  
pp. 1217-1227 ◽  
Author(s):  
Adam J. Trewin ◽  
Aaron C. Petersen ◽  
Francois Billaut ◽  
Leon R. McQuade ◽  
Bernie V. McInerney ◽  
...  
Keyword(s):  
Power Output ◽  
High Intensity ◽  
Repeated Measures ◽  
Vastus Lateralis ◽  
Venous Blood ◽  
Time Trial ◽  
Peak Power Output ◽  
Mean Power ◽  
Double Blind ◽  
Substrate Metabolism

We investigated the effects of N-acetylcysteine (NAC) on metabolism during fixed work rate high-intensity interval exercise (HIIE) and self-paced 10-min time-trial (TT10) performance. Nine well-trained male cyclists (V̇O2peak, 69.4 ± 5.8 mL·kg−1·min−1; peak power output (PPO), 385 ± 43 W; mean ± SD) participated in a double-blind, repeated-measures, randomised crossover trial. Two trials (NAC supplementation and placebo) were performed 7 days apart consisting of 6 × 5 min HIIE bouts at 82% PPO (316 ± 40 W) separated by 1 min at 100 W, and then after 2 min of recovery at 100 W, TT10 was performed. Expired gases, venous blood, and electromyographic (EMG) data were collected. NAC did not influence blood glutathione but decreased lipid peroxidation compared with the placebo (P < 0.05). Fat oxidation was elevated with NAC compared with the placebo during HIIE bouts 5 and 6 (9.9 ± 8.9 vs. 3.9 ± 4.8 μmol·kg−1·min−1; P < 0.05), as was blood glucose throughout HIIE (4.3 ± 0.6 vs. 3.8 ± 0.6 mmol·L−1; P < 0.05). Blood lactate was lower with NAC after TT10 (3.3 ± 1.3 vs. 4.2 ± 1.3 mmol·L−1; P < 0.05). Median EMG frequency of the vastus lateralis was lower with NAC during HIIE (79 ± 10 vs. 85 ± 10 Hz; P < 0.05), but not TT10 (82 ± 11 Hz). Finally, NAC decreased mean power output 4.9% ± 6.6% (effect size = –0.3 ± 0.4, mean ± 90% CI) during TT10 (305 ± 57 W vs. 319 ± 45 W). These data suggest that NAC alters substrate metabolism and muscle fibre type recruitment during HIIE, which is detrimental to time-trial performance.

scholarly journals How Relevant Is the Place Where First-Year College Students Live in Relation to the Increase in Body Mass Index?

Healthcare ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 1638
Author(s):  
Antonio Viñuela ◽  
Juan José Criado-Álvarez ◽  
Javier Aceituno-Gómez ◽  
Carlos Durantez-Fernández ◽  
José Luis Martín-Conty ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Nursing Students ◽  
Body Mass ◽  
Repeated Measures ◽  
Eating Habits ◽  
The Body ◽  
P Value ◽  
First Year ◽  
Significant Difference ◽  
The Mean

(1) Objective: This study analyzes the evolution of the body mass index (BMI) throughout the academic year associated with changes in the lifestyle associated with the place where students live during the course, lifestyle design, and health strategies for the university community. (2) Methods: A total of 93 first-year nursing students participated in this study. Data were collected throughout the course by administering self-reported questionnaires about eating habits and lifestyles, weight, and height to calculate their BMI and place of residence throughout the course. Data were analyzed using statistical analysis (Mann–Whitney, chi-square, Student’s t-test, repeated-measures analysis of variance, and least significant difference tests). (3) Results: We found that the mean BMI increases significantly throughout the course among all students regardless of sex, age, eating habits, or where they live during the course. At the beginning of the course, the mean BMI was 22.10 ± 3.64. The mean difference between the beginning of the course and the middle has a value of p-value < 0.015 and between the middle of the course and the end a p-value < 0.009. The group that increased the most is found among students who continue to live in the family nucleus rather than those who live alone or in residence. Students significantly changed their eating and health habits, especially those who live alone or in residence. (4) Conclusions: There is an increase in BMI among students. It is necessary to carry out seminars or talks that can help students understand the importance of good eating practices and healthy habits to maintain their weight and, therefore, their health, in the short, medium, and long term and acquire a good quality of life.

scholarly journals Effect of Wingate-based high intensity interval training on aerobic and anaerobic performance of kick boxers

2018 ◽  
Vol 23 (4) ◽  
pp. 167-171 ◽  
Author(s):  
M.S. Akgül
Keyword(s):  
Body Mass ◽  
High Intensity ◽  
Interval Training ◽  
Anaerobic Performance ◽  
High Intensity Interval Training ◽  
Significant Difference ◽  
Post Test ◽  
High Intensity Interval ◽  
Experimental Group ◽  
Aerobic And Anaerobic

Purpose: The aim of this study was to investigate the effects of two-week high intensity interval training (HIIT) on aerobic and anaerobic performance of kick boxers. Material: 24 male kick boxers (age 19.39 ± 0.72 y, body mass 74.14 ± 6.22 kg, height 177.95 ± 5.29 cm) volunteered for the study. Participants were randomly divided into two groups: experimental and control. As well as routine training program, experimental group carried out Wingate-based HIIT 3 times per week for two weeks. Wingate protocol was as follow: 4 repetitions with 4 mins recovery (4X30sn all-out effort) during the first week, 5 repetitions with 4 mins recovery (5X30sn all-out effort) during the second week. In order to determine aerobic capacity, 20m shuttle run test was used while Wingate anaerobic test was used to determine anaerobic performance. Descriptive statistic was used to demonstrate mean values and standard deviation of the variables. Non-parametric Mann Whitney-U test was used to show the differences between groups. Wilcoxon Signed Rank Test was used to compare intra-groups results from pre and post-test applications. Results: There was no significant difference between groups during pre-test measurements There was significant difference in PP, MP in experimental group compared to control during the post-test measurements. There was no difference in body mass, body fat (%) and predicted VO2max in both groups between measurements. Conclusions: According to intra and inter-group results, it can be concluded that two-week Wingate-based HIIT can be used to improve aerobic and anaerobic performances of kick boxers.

Acute effects of chocolate milk and a commercial recovery beverage on postexercise recovery indices and endurance cycling performance

2009 ◽  
Vol 34 (6) ◽  
pp. 1017-1022 ◽  
Author(s):  
Kelly Pritchett ◽  
Philip Bishop ◽  
Robert Pritchett ◽  
Matt Green ◽  
Charlie Katica
Keyword(s):  
Oxygen Uptake ◽  
Maximal Oxygen Uptake ◽  
High Intensity ◽  
Repeated Measures ◽  
Intermittent Exercise ◽  
Cycling Performance ◽  
Exercise Session ◽  
Time To Exhaustion ◽  
Chocolate Milk ◽  
Significant Difference

To maximize training quality, athletes have sought nutritional supplements that optimize recovery. This study compared chocolate milk (CHOC) with a carbohydrate replacement beverage (CRB) as a recovery aid after intense exercise, regarding performance and muscle damage markers in trained cyclists. Ten regional-level cyclists and triathletes (maximal oxygen uptake 55.2 ± 7.2 mL·kg–1·min–1) completed a high-intensity intermittent exercise protocol, then 15–18 h later performed a performance trial at 85% of maximal oxygen uptake to exhaustion. Participants consumed 1.0 g carbohydrate·kg–1·h–1 of a randomly assigned isocaloric beverage (CHOC or CRB) after the first high-intensity intermittent exercise session. The same protocol was repeated 1 week later with the other beverage. A 1-way repeated measures analysis of variance revealed no significant difference (p = 0.91) between trials for time to exhaustion at 85% of maximal oxygen uptake (CHOC 13 ± 10.2 min, CRB 13.5 ± 8.9 min). The change in creatine kinase (CK) was significantly (p < 0.05) greater in the CRB trial than in the CHOC trial (increase CHOC 27.9 ± 134.8 U·L–1, CRB 211.9 ± 192.5 U·L–1), with differences not significant for CK levels before the second exercise session (CHOC 394.8 ± 166.1 U·L–1, CRB 489.1 ± 264.4 U·L–1) between the 2 trials. These findings indicate no difference between CHOC and this commercial beverage as potential recovery aids for cyclists between intense workouts.

scholarly journals The Effects of High Doses of Caffeine on Maximal Strength and Muscular Endurance in Athletes Habituated to Caffeine

Nutrients ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1912 ◽  
Author(s):  
Michal Wilk ◽  
Michal Krzysztofik ◽  
Aleksandra Filip ◽  
Adam Zajac ◽  
Juan Del Coso
Keyword(s):  
Body Mass ◽  
Repeated Measures ◽  
Bench Press ◽  
Muscle Endurance ◽  
Experimental Session ◽  
Maximal Strength ◽  
Double Blind ◽  
Significant Difference ◽  
Endurance Tests ◽  
Double Blind Design

Background: The main goal of this study was to assess the acute effects of the intake of 9 and 11 mg/kg/ body mass (b.m.) of caffeine (CAF) on maximal strength and muscle endurance in athletes habituated to caffeine. Methods: The study included 16 healthy strength-trained male athletes (age = 24.2 ± 4.2 years, body mass = 79.5 ± 8.5 kg, body mass index (BMI) = 24.5 ± 1.9, bench press 1RM = 118.3 ± 14.5 kg). All participants were habitual caffeine consumers (4.9 ± 1.1 mg/kg/b.m., 411 ± 136 mg of caffeine per day). This study had a randomized, crossover, double-blind design, where each participant performed three experimental sessions after ingesting either a placebo (PLAC) or 9 mg/kg/b.m. (CAF-9) and 11 mg/kg/b.m. (CAF-11) of caffeine. In each experimental session, participants underwent a 1RM strength test and a muscle endurance test in the bench press exercise at 50% 1RM while power output and bar velocity were measured in each test. Results: A one-way repeated measures ANOVA revealed a significant difference between PLAC, CAF-9, and CAF-11 groups in peak velocity (PV) (p = 0.04). Post-hoc tests showed a significant decrease for PV (p = 0.04) in the CAF-11 compared to the PLAC group. No other changes were found in the 1RM or muscle endurance tests with the ingestion of caffeine. Conclusion: The results of the present study indicate that high acute doses of CAF (9 and 11 mg/kg/b.m.) did not improve muscle strength nor muscle endurance in athletes habituated to this substance.

scholarly journals How Relevant Is the Place Where First-Year College Students Live In Relation to the Increase in Body Mass Index?

2021 ◽  
Author(s):  
Antonio Viñuela ◽  
Juan José Criado-Álvarez ◽  
Javier Aceituno-Gomez ◽  
Carlos Durantez-Fernández ◽  
Jose Luis Martin-Conty ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Nursing Students ◽  
Body Mass ◽  
Repeated Measures ◽  
Eating Habits ◽  
The Body ◽  
P Value ◽  
First Year ◽  
Significant Difference ◽  
The Mean

(1) Objective: This study analyzes the evolution of the body mass index (BMI) throughout the academic year associated with changes in the lifestyle associated with the place where they live during the course and design lifestyle and health strategies to the university community. (2) Methods: 93 first-year nursing students participated in this study. Data were collected throughout the course by administering self-reported questionnaires about eating habits and lifestyles, weight, and height to calculate their BMI and place of residence throughout the course. Data were analyzed using statistical analysis (Mann-Whitney, Chi-square, student's t- test, repeated-measures analysis of variance, and least significant difference tests). (3) Results: We found that the mean BMI increases significantly throughout the course among all students regardless of sex, age, eating habits or where they live during the course. At the beginning course the mean BMI was 22.1 &plusmn; 3,642. The mean difference between the beginning of the course and the middle has a value of p value &amp;lt;0. 015 and between the middle of the course and the end a p value &amp;lt;0.009. The group that increased the most is found among students who continue to live in the family nucleus rather than those who live alone or in residence. Students significantly change their eating and health habits, especially those who live alone or in residences.: (4) Conclusions: There is an increase in BMI among students. It is necessary to carry out seminars or talks that can help students understand the importance of good eating practices and healthy habits to maintain their weight and, therefore, their health, in the short, medium, and long term and acquire a good quality of life.

Sign in / Sign up

Export Citation Format

Share Document