scholarly journals Caffeine Timing Improves Lower-Body Muscular Performance: A Randomized Trial

2020 ◽  
Vol 7 ◽  
Author(s):  
Patrick S. Harty ◽  
Hannah A. Zabriskie ◽  
Richard A. Stecker ◽  
Brad S. Currier ◽  
Grant M. Tinsley ◽  
...  
Keyword(s):  
Body Mass ◽  
Knee Extensor ◽  
Optimal Time ◽  
Crossover Fashion ◽  
Time Interval ◽  
Lower Body ◽  
Caffeine Consumption ◽  
Double Blind ◽  
Time Points ◽  
Muscular Performance

Little is known about the optimal time to consume caffeine prior to exercise to maximize the ergogenic benefits of the substance.Purpose: To determine the optimal pre-exercise time interval to consume caffeine to improve lower-body muscular performance. A secondary aim was to identify the presence of any sex differences in responses to timed caffeine administration.Methods: Healthy, resistance-trained males (n = 18; Mean±SD; Age: 25.1 ± 5.7 years; Height: 178.4 ± 7.1 cm; Body mass: 91.3 ± 13.5 kg; Percent body fat: 20.7 ± 5.2; Average caffeine consumption: 146.6 ± 100.3 mg/day) and females (n = 11; Mean ± SD; Age: 20.1 ± 1.6 years; Height: 165.0 ± 8.8 cm; Body mass: 65.8 ± 10.0 kg; Percent bodyfat: 25.8 ± 4.2; Average caffeine consumption: 111.8 ± 91.7 mg/day) participated in this investigation. In a randomized, double-blind, placebo-controlled, crossover fashion, participants consumed 6 mg·kg−1 caffeine or placebo solution at three time points: 2 h prior (2H), 1 h prior (1H), or 30 min prior (30M) to exercise testing. During three visits, caffeine was randomly administered at one time point, and placebo was administered at the other two time points. During one visit, placebo was administered at all three time points. Next, participants performed isometric mid-thigh pulls (IMTP), countermovement vertical jumps (CMVJ), and isometric/isokinetic knee extensor testing (ISO/ISOK).Results: Caffeine administered at 1H significantly improved absolute CMVJ and ISO performance relative to placebo. Mean CMVJ jump height was significantly higher during 1H compared to 30M. However, only caffeine administered at 30M significantly improved absolute measures of isokinetic performance. Analysis of the pooled caffeine conditions revealed that muscular performance was more consistently augmented by caffeine in males compared to females.Conclusions: Pre-exercise caffeine timing significantly modulated participant responses to the substance, with 1H exerting the most consistent ergogenic benefits relative to other time points, particularly compared to 2H. Male participants were found to respond more consistently to caffeine compared to female participants. These results suggest that active individuals can maximize the ergogenic effects of caffeine by consuming the substance ~1 h prior to the point when peak muscular performance is desired.

Body Dissatisfaction as a Motivator for Weight Loss: Should Assessment of Body Dissatisfaction be Considered in Primary Health Settings for Women Planning to Lose Weight?

2006 ◽  
Vol 12 (3) ◽  
pp. 85
Author(s):  
Lynette Evans ◽  
Lisa Meehan
Keyword(s):  
Body Mass Index ◽  
Weight Loss ◽  
Body Dissatisfaction ◽  
Body Mass ◽  
Self Concept ◽  
Lower Body ◽  
Time Points ◽  
Primary Health ◽  
Previous Weight Loss ◽  
Low Bmi

The objective of this study was to assess whether body dissatisfaction predicted weight loss in terms of an inverted U relationship. It was predicted that women with high and low body dissatisfaction were less likely to lose weight than women with moderate levels of body dissatisfaction. The study also sought to determine if the number of weight loss attempts, success at past weight loss and self-concept predicted percentage of weight loss in women at six months; and to test whether weight loss led to decreased body dissatisfaction and increased self-concept. Women attempting to lose weight (n = 209) were asked to complete a set of questionnaires at two time points. Results show that women with moderate scores on body dissatisfaction lost more weight than women with higher or lower scores, although this association disappeared when Body Mass Index (BMI) was controlled for in the analyses. Low BMI, success of previous weight loss and low personal self-concept predicted weight loss six months later. Women who lost weight reported lower body dissatisfaction and improved self-concept. It was concluded that, assessing for body dissatisfaction, BMI and weight loss history in the context of primary health settings, may aid in identifying women able to motivate themselves to successfully lose weight in a self-directed manner.

The effects of low and moderate doses of caffeine supplementation on upper and lower body maximal voluntary concentric and eccentric muscle force

2018 ◽  
Vol 43 (3) ◽  
pp. 274-281 ◽  
Author(s):  
Jason Tallis ◽  
Harley C.M. Yavuz
Keyword(s):  
Body Mass ◽  
Muscular Strength ◽  
Muscle Performance ◽  
Upper Body ◽  
Knee Extensors ◽  
Elbow Flexors ◽  
Lower Body ◽  
Double Blind ◽  
Concentric Force ◽  
Dose Response Effect

Despite the growing quantity of literature exploring the effect of caffeine on muscular strength, there is a dearth of data that directly explores differences in erogenicity between upper and lower body musculature and the dose–response effect. The present study sought to investigate the effects of low and moderate doses of caffeine on the maximal voluntary strength of the elbow flexors and knee extensors. Ten nonspecifically strength-trained, recreationally active participants (aged 21 ± 0.3 years) completed the study. Using a randomised, counterbalanced, and double-blind approach, isokinetic concentric and eccentric strength was measured at 60 and 180°/s following administration of a placebo, 3 mg·kg−1 body mass caffeine, and 6 mg·kg−1 body mass caffeine. There was no effect of caffeine on the maximal voluntary concentric and eccentric strength of the elbow flexors, or the eccentric strength of the knee extensors. Both 3 and 6 mg·kg−1 body mass caffeine caused a significant increase in peak concentric force of the knee extensors at 180°/s. No difference was apparent between the 2 concentrations. Only 6 mg·kg−1 body mass caused an increase in peak concentric force during repeated contractions. The results infer that the effective caffeine concentration to evoke improved muscle performance may be related to muscle mass and contraction type. The present work indicates that a relatively low dose of caffeine treatment may be effective for improving lower body muscular strength, but may have little benefit for the strength of major muscular groups of the upper body.

scholarly journals Dispelling the myth that habitual caffeine consumption influences the performance response to acute caffeine supplementation

2017 ◽  
Vol 123 (1) ◽  
pp. 213-220 ◽  
Author(s):  
Lívia de Souza Gonçalves ◽  
Vitor de Salles Painelli ◽  
Guilherme Yamaguchi ◽  
Luana Farias de Oliveira ◽  
Bryan Saunders ◽  
...  
Keyword(s):  
Body Mass ◽  
Exercise Performance ◽  
Perceived Exertion ◽  
Mixed Model ◽  
Analysis Of Covariance ◽  
Caffeine Intake ◽  
Caffeine Consumption ◽  
Double Blind ◽  
Performance Effects ◽  
Cycling Time

This study investigates the influence of habitual caffeine intake on aerobic exercise-performance responses to acute caffeine supplementation. A double-blind, crossover, counterbalanced study was performed. Forty male endurance-trained cyclists were allocated into tertiles, according to their daily caffeine intake: low (58 ± 29 mg/d), moderate (143 ± 25 mg/d), and high (351 ± 139 mg/d) consumers. Participants completed three trials in which they performed simulated cycling time trials (TTs) in the fastest time possible following ingestion of the following: caffeine (CAF: 6 mg/kg body mass), placebo (PLA), and no supplement (CON). A mixed-model analysis revealed that TT performance was significantly improved in CAF compared with PLA and CON (29.92 ± 2.18 vs. 30.81 ± 2.67 and 31.14 ± 2.71 min, respectively; P = 0.0002). Analysis of covariance revealed no influence of habitual caffeine intake as a covariate on exercise performance ( P = 0.47). TT performance was not significantly different among tertiles ( P = 0.75). No correlation was observed between habitual caffeine intake and absolute changes (CAF − CON) in TT performance with caffeine ( P = 0.524). Individual analysis showed that eight, seven, and five individuals improved above the variation of the test in CAF in the low, moderate, and high tertiles, respectively. A Fisher’s exact test did not show any significant differences in the number of individuals who improved in CAF among the tertiles ( P > 0.05). Blood lactate and ratings of perceived exertion were not different between trials and tertiles ( P > 0.05). Performance effects of acute caffeine supplementation during an ~30-min cycling TT performance were not influenced by the level of habitual caffeine consumption. NEW & NOTEWORTHY There has been a long-standing paradigm that habitual caffeine intake may influence the ergogenicity of caffeine supplementation. Low, moderate, and high caffeine consumers showed similar absolute and relative improvements in cycling time-trial performance following acute supplementation of 6 mg/kg body mass caffeine. Performance effects of acute caffeine were not influenced by the level of habitual caffeine consumption, suggesting that high habitual caffeine intake does not negate the benefits of acute caffeine supplementation.

Allergy

PEDIATRICS ◽  
1992 ◽  
Vol 90 (2) ◽  
pp. 285-293
Keyword(s):  
Drug Administration ◽  
Healthy Subjects ◽  
Pharmacokinetic Interaction ◽  
Physical Symptoms ◽  
Drug Combinations ◽  
Crossover Fashion ◽  
Caffeine Consumption ◽  
Double Blind ◽  
Study Population ◽  
Time Basis

PATHOPHYSIOLOGY PHENYLPROPANOLAMINE INCREASES PLASMA CAFFEINE LEVELS Lake CR, Rosenberg DB, Gallant S, Zaloga G, Chernow B. Clin Pharmacol Ther. 1990;47:675-685 Purpose of the Study The purpose of the study was to examine the possible pharmacokinetic interaction of concurrent theophylline and caffeine administration. Study Population Sixteen healthy subjects (13 men, 3 women) were included in the study. Subject caffeine consumption ranged from 20 to 1200 mg/d (mean, 251 ± 73 mg/d). Seven subjects smoked at least a half pack of cigarettes per day. Methods The subjects received each of the following drug combinations on a one-time basis in a double-blind, crossover fashion: 400 mg of caffeine, 400 mg of caffeine in combination with 75 mg of phenylpropanolamine, and placebo. Ten of the subjects completed all four drug combinations. One subject received three drug combinations, three subjects received two drug combinations, and two subjects received one drug combination. Serum was collected 5 minutes before drug administration, and at ½, 1, 1½, 2, 3, 4, and 5 hours after drug administration. The serum was assessed for caffeine, norepinephrine, and epinephrine levels. Heart rate and blood pressure were measured 2½ and 5 minutes for drug administration and at 15-minute intervals for 5 hours after drug administration. The patients also filled out a 21-item mood and physical symptoms questionnaire 25 minutes before receiving the medication and 1½ and 4 hours after its administration. Findings Caffeine levels after ingestion of the phenylpropanolamine-caffeine combination were significantly higher than those of the other drug combinations from 1 to 5 hours after administration.

scholarly journals Male Sex, Decreased Activity Level, and Higher BMI Associated With Lower Completion of Patient-Reported Outcome Measures Following ACL Reconstruction

2018 ◽  
Vol 6 (3) ◽  
pp. 232596711875860 ◽  
Author(s):  
Eric J. Cotter ◽  
Charles P. Hannon ◽  
Philip Locker ◽  
Annabelle Davey ◽  
Kevin C. Wang ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Body Mass ◽  
Patient Reported Outcome ◽  
Activity Level ◽  
Completion Rates ◽  
Lower Body ◽  
Time Points ◽  
Lower Body Mass Index ◽  
Patient Reported ◽  
Male Sex

Background: Patient-reported outcome (PRO) surveys have become increasingly important in both improving patient care and assessing outcomes. Purpose/Hypothesis: The purpose of this study was to evaluate which variables are associated with compliance with completing PRO surveys in patients who have undergone anterior cruciate ligament reconstruction (ACLR). The authors hypothesized that older patient age and longer time since ACLR would be associated with lower completion rates of PRO surveys preoperatively and at postoperative time points. Study Design: Case series; Level of evidence, 4. Methods: All patients who underwent ACLR by a sports medicine fellowship–trained orthopaedic surgeon at a single institution and were electronically assigned PRO surveys through a data collection system preoperatively between December 2013 and March 2015 were included. Postoperatively, PRO surveys were sent to patients’ email addresses at 6, 12, and 24 months. Demographics, history, and operative and postoperative information were evaluated for an association with survey completion rates. Results: A total of 256 patients met the inclusion criteria. There were 140 (54.7%) male and 116 (45.3%) female patients, with an overall mean age of 28.6 ± 11.9 years. Only 19 (7.4%) patients completed all preoperative and postoperative surveys at all time points. Less than half of the patients (n = 104; 40.6%) completed both the preoperative survey and at least 1 postoperative survey. There was a steady decrease in the completion rate of PRO surveys postoperatively over time (Pearson r = –0.995, P = .005). Male patients had significantly worse compliance with completing PRO surveys preoperatively and at a minimum of 1 time point postoperatively ( P = .044). Patients who did not identify as athletes or report frequent exercise (≥3 times/wk) had significantly worse compliance with completing any PRO surveys ( P = .046). Lower body mass index was associated with greater odds of compliance with completing the preoperative survey and 24-month postoperative survey (odds ratio, 0.902; P = .029). Conclusion: An inverse relationship was found between the surgery-to-survey period and percentage of those completing PRO surveys, with poor overall compliance. Male sex and not self-identifying as an athlete or performing frequent physical exercise were associated with lower completion rates of PRO surveys, while lower body mass index was associated with a greater rate of completion.

scholarly journals Relationships Between Measures of Functional and Isometric Lower Body Strength, Aerobic Capacity, Anaerobic Power, Sprint and Countermovement Jump Performance in Professional Soccer Players

2020 ◽  
Vol 75 (1) ◽  
pp. 161-175
Author(s):  
Michał Boraczyński ◽  
Tomasz Boraczyński ◽  
Robert Podstawski ◽  
Zbigniew Wójcik ◽  
Piotr Gronek
Keyword(s):  
Body Mass ◽  
Aerobic Capacity ◽  
Anaerobic Power ◽  
Knee Extensor ◽  
Soccer Players ◽  
Lower Body ◽  
Countermovement Jump ◽  
Body Strength ◽  
Wide Range ◽  
Lower Body Strength

Abstract The purpose of this study was to assess a wide range of physiological and performance variables and investigate whether and to what extent these variables are associated with each other in soccer. Twenty-five male soccer players (25.1 ± 4.56 years; body mass, 75.2 ± 5.92 kg; body height, 180.6 ± 5.45 cm) performed: 5- and 30-m sprints (T5m and T30m, respectively), 1-repetition-maximum (1RM) half squat, maximal voluntary isometric contraction (MVIC) of the knee extensors, countermovement jump (CMJ) to obtain vertical jump height (CMJheight) and power output (CMJpower), the 10-s Wingate Anaerobic Test (WAnT) to obtain peak power (Pmax), and the 20-m multi-stage shuttle run test (MST) to evaluate aerobic capacity. 1RM, MVIC, and Pmax were normalized to body mass. Large negative correlations were found between sprint times and 1RM half back squat/BM (r = -0.510 to -0.570, r2 = 0.260–0.325, both p < 0.01) and Pmax/BM (r = -0.501, r2 = 0.251, p < 0.01). T30m most strongly and negatively correlated with CMJheight (r = -0.744, r2 = 0.554, p < 0.001). WAnT-determined Pmax showed a very large correlation between absolute Pmax and knee-extensor MVIC (r = 0.827, r2 = 0.684, p < 0.001) and large correlations between absolute Pmax and 1RM half squat (r = 0.674, r2 = 0.454, p < 0.001) and CMJpower (r = 0.579, r2 = 0.335, p < 0.01). We also identified a large inverse relationship between CMJheight and T30m (r = -0.744, r2 = 0.554, p < 0.001) and large positive correlation between CMJheight and MVIC/BM (r = 0.702, p < 0.001). The results demonstrate that elite soccer players with greater lower body strength (quantified by the MVIC of the knee extensor and the 1RM half squat) show better sprint and CMJ performance, suggesting the incorporation of soccer-specific resistance training to develop lower body musculature and therefore maximize sprinting ability. The higher correlation coefficients found between T30m and the physiological and athletic measures compared with T5m promote the use of this sprint distance when assessing performance. The use of relative measures (normalized to body mass) is advisable when comparing strength variables with sprint and CMJ performance or anaerobic power. Considering the correlations of WAnT-determined Pmax versus CMJpower, coaches should administer tests that assess jumping and linear sprint performance rather than the cycling-specific WAnT.

scholarly journals Construction of Windows for Pharmacokinetic Sampling

2021 ◽  
Vol 50 (5) ◽  
pp. 23-37
Author(s):  
M. Iftakhar Alam ◽  
Nigar Sultana
Keyword(s):  
Random Time ◽  
Optimal Time ◽  
Parameter Estimates ◽  
Time Interval ◽  
Sample Collection ◽  
Maximum Information ◽  
Blood Samples ◽  
Time Points ◽  
Optimal Criterion ◽  
Sampling Windows

This paper describes a method for the construction of pharmacokinetic sampling windows so that they are around the $D$-optimum time points. Here we consider the situation where a pharmacokinetic (PK) study is accompanied by a dose-finding study in phase I clinical trial. The D-optimal criterion is often used to determine the optimal time for collecting blood samples so that they provide maximum information regarding the population PK parameters. However, collecting blood samples at the D-optimal time points is often difficult. Instead, the sampling time point chosen from a suitable time interval or window can ease the process. The proposed method is conceptually simple and considers the average value and standard deviation of D-optimal time points up to create sampling windows. Random time points can be chosen from these windows then to collect blood samples from the next cohort. The nonlinear random-effects model has been used to model the PK data. Also, we employ the continual reassessment method for dose allocation to the patients. Comparisons of the accuracy and precision for the PK parameter estimates obtained at the D-optimal and random time points are also presented. The results are convincing enough to suggest the proposed method as a useful tool for blood sample collection.

Utilization of remote sensing for estimation of scale of cutting and growing of forest zones

2017 ◽  
Vol 920 (2) ◽  
pp. 57-60
Author(s):  
F.E. Guliyeva
Keyword(s):  
Remote Sensing ◽  
Fixed Time ◽  
Time Interval ◽  
Time Points ◽  
Average Value ◽  
Time Period ◽  
Remote Estimation ◽  
The Given ◽  
Forest Cutting

The study of results of relevant works on remote sensing of forests has shown that the known methods of remote estimation of forest cuts and growth don’t allow to calculate the objective average value of forests cut volume during the fixed time period. The existing mathematical estimates are not monotonous and make it possible to estimate primitively the scale of cutting by computing the ratio of data in two fixed time points. In the article the extreme properties of the considered estimates for deforestation and reforestation models are researched. The extreme features of integrated averaged values of given estimates upon limitations applied on variables, characterizing the deforestation and reforestation processes are studied. The integrated parameter, making it possible to calculate the averaged value of estimates of forest cutting, computed for all fixed time period with a fixed step is suggested. It is shown mathematically that the given estimate has a monotonous feature in regard of value of given time interval and make it possible to evaluate objectively the scales of forest cutting.

scholarly journals Caffeine improves biochemical and specific performance after judo training: a double-blind crossover study in a real judo training situation

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Kelvin Euton Oliveira Carmo ◽  
Diego Ignácio Valenzuela Pérez ◽  
Charles Nardelli Valido ◽  
Jymmys Lopes dos Santos ◽  
Bianca Miarka ◽  
...  
Keyword(s):  
Heart Rate ◽  
Uric Acid ◽  
Body Mass ◽  
Perceived Exertion ◽  
Rating Of Perceived Exertion ◽  
Power Performance ◽  
Double Blind ◽  
Biochemical Effect ◽  
Plasma Uric Acid ◽  
Hemodynamic Variables

Abstract Background Nutritional ergogenic aids are foods or nutrients that can improve physical performance. Among these foods with ergogenic properties, caffeine has shown that it can increase the fat catabolism, strength, and improve the cognition and time reaction of an athlete, therefore, it is hoped that it can improve the performance of judokas. This study through a double-blind crossover (supplement X placebo) protocol, investigated the effects caffeine supplementation (single capsule containing 5 mg/kg body mass intake 60 min before the session) on biochemical, anthropometrical, physical, subjective and hemodynamic variables measured before, during and after two typical judo trainingcxs sessions (120-min: 40-min of gymnastics; 40-min of specific technics and; 40-min of judo combat). Methods 8 high-level athletes (21.4 ± 2.0 years; 83.6 ± 15.2 kg; 1.8 ± 0.1 m; 17.9 ± 7.0 Fat%) were evaluated before and after each training for body mass, hydration, upper and lower limb power, performance in the special judo fitness test (SJFT), free fatty acids (FFA) in plasma, uric acid, glucose, lactate, heart rate, and pain. In addition, heart rate, FFA in plasma, uric acid, glucose, lactate, rating of perceived exertion and pain were assessed during the training. Results At 120 min, supplementation resulted in a higher concentration of plasma FFA (1.5 ± 0.5 vs. 1.0 ± 0.3 mmol/L; p = 0.047) and lactate (4.9 ± 1.8 vs. 3.0 ± 1.2 mmol/L; p = 0.047), and a lower concentration of uric acid (5.4 ± 0.9 vs. 7.0 ± 1.5 mg/dL; p = 0.04). Supplementation also resulted in performance maintenance (fatigue index) in the SJFT (Δ0.3 ± 2.0 vs Δ1.7 ± 2.5, for caffeine and placebo respectively, p = 0.046). No adverse effects were observed. Conclusion Based on the applied dose, intake time, and sample of this study, we can conclude that caffeine produces an ergogenic biochemical effect, and improves performance in judo athletes.

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