Effects of mental imagery on muscular strength in healthy and patient participants: A systematic review

The aims of the present review were to (i) provide a critical overview of the current literature on the effects of mental imagery on muscular strength in healthy participants and patients with immobilization of the upper extremity (i.e., hand) and anterior cruciate ligament (ACL), (ii) identify potential moderators and mediators of the “mental imagery-strength performance” relationship and (iii)determine the relative contribution of electromyography(EMG) and brain activities, neural and physiological adaptations in the mental imagery-strength performance relationship. This paper also discusses the theoretical and practical implications of the contemporary literature and suggests possible directions for future research. Overall, the results reveal that the combination of mental imagery and physical practice is more efficient than, or at least comparable to, physical execution with respect to strength performance. Imagery prevention intervention was also effective in reducing of strength loss after short-term muscle immobilization and ACL. The present review also indicates advantageous effects of internal imagery (range from 2.6 to 136.3%) for strength performance compared with external imagery (range from 4.8 to 23.2%). Typically, mental imagery with muscular activity was higher in active than passive muscles, and imagining “lifting a heavy object” resulted in more EMG activity compared with imagining “lifting a lighter object”. Thus, in samples of students, novices, or youth male and female athletes, internal mental imagery has a greater effect on muscle strength than external mental imagery does. Imagery ability, controllability, past experiences, and self-efficacy have been shown to be the variables mediating the effect of mental imagery on strength performance. Finally, the greater effects of internal imagery than those of external imagery could be explained in terms of neural adaptations, stronger brain activation, higher muscle excitation, greater somatic and sensorimotor activation and physiological responses such as blood pressure, heart rate, and respiration rate

The Importance of Monitoring Sleep within Adolescent Athletes: Athletic, Academic, and Health Considerations

Opinion piece

Sleep Medication and Athletic Performance—The Evidence for Practitioners and Future Research Directions

Opinion piece

Anthropometric and physical characteristics allow differentiation of young female volleyball players according to playing position and level of expertise

The aim of our study was to determine the differences in some anthropometric and physical performance variables of young Croatian female volleyball players (aged 13 to 15) in relation to playing position (i.e., independent variable) and performance level within each position (i.e., independent variable). Players were categorized according to playing position (i.e., role) as middle blockers (n=28), opposite hitters (n=41), passer-hitters (n=54), setters (n=30), and liberos (n=28). Within each position, players were divided into a more successful group and a less successful group according to team ranking in the latest regional championship and player quality within the team. Height and body mass, somatotype by the Heath-Carter method, and four tests of lower body power, speed, agility and upper body power (i.e., dependent variables) were assessed. Players in different positions differed significantly in height and all three somatotype components, but no significant differences were found in body mass, body mass index or measured physical performance variables. Players of different performance level differed significantly in both anthropometric and physical performance variables. Generally, middle blockers were taller, more ectomorphic, less mesomorphic and endomorphic, whereas liberos were shorter, less ectomorphic, more mesomorphic and endomorphic than players in other positions. More successful players in all positions had a lower body mass index, were less mesomorphic and endomorphic, and more ectomorphic than less successful players. Furthermore, more successful players showed better lower body power, speed, agility and upper body power. The results of this study can potentially provide coaches with useful indications about the use of somatotype selection and physical performance assessment for talent identification and development

Greater effects of high- compared with moderate-intensity interval training on cardio-metabolic variables, blood leptin concentration and ratings of perceived exertion in obese adolescent females

This study examined the effects of high- vs. moderate-intensity interval training on cardiovascular fitness, leptin levels and ratings of perceived exertion (RPE) in obese female adolescents. Forty-seven participants were randomly assigned to one of three groups receiving either a 1:1 ratio of 15 s of effort comprising moderate-intensity interval training (MIIT at 80% maximal aerobic speed: MAS) or high-intensity interval training (HIIT at 100% MAS), with matched 15 s recovery at 50% MAS, thrice weekly, or a no-training control group. The HIIT and MIIT groups showed improved (p < 0.05) body mass (BM), BMI Z-score, and percentage of body fat (%BF). Only the HIIT group showed decreased waist circumference (WC) (p = 0.017). The effect of exercise on maximal oxygen uptake (VO2max) was significant (p = 0.019, ES = 0.48 and p = 0.010, ES = 0.57, HIIT and MIIT, respectively). The decrease of rate-pressure product (RPP) (p < 0.05, ES = 0.53 and ES = 0.46, HIIT and MIIT, respectively) followed the positive changes in resting heart rate and blood pressures. Blood glucose, insulin level and the homeostasis model assessment index for insulin decreased (p < 0.05) in both training groups. Significant decreases occurred in blood leptin (p = 0.021, ES = 0.67 and p = 0.011, ES = 0.73) and in RPE (p = 0.001, ES = 0.76 and p = 0.017, ES = 0.57) in HIIT and MIIT, respectively. In the post-intervention period, blood leptin was strongly associated with %BF (p < 0.001) and VO2max (p < 0.01) in the HIIT and MIIT groups, respectively, while RPE was strongly associated with BM (p < 0.01) in the HIIT group. The results suggest that high-intensity interval training may produce more positive effects on health determinants in comparison with the same training mode at a moderate intensity.Ministry of Higher Education, Scientific Research and Technology of Tunisia

Association between vitamin A and E and apolipoprotein A and B levels in type 2 diabetes

Objective. To determine the relationship between serum vitamin A and E and apolipoprotein levels in type 2 diabetic patients. Setting. Shariati Hospital, Tehran, Iran. Subjects and methods. One hundred and seventeen eligible type 2 diabetic patients who attended the Endocrine Research and Metabolism Center between 2002 and 2004 were enrolled in the study. Blood samples were collected after a 12 - 14-hour overnight fast for the measurement of serum levels of total cholesterol, triglyceride, high-density lipoprotein (HDL), low-density lipoprotein (LDL), apolipoprotein (apo) A1 and apoB, and vitamins A and E. Anthropometric indices were determined by physical examination. Data were analysed statistically using Pearson's coefficient, multiple regression, and partial and bivariate correlations. Results. The mean body mass index (BMI) of the subjects was 27.4 ± 3.7 kg/m2. The mean (± standard deviation (SD)) serum levels of vitamins A and E were 0.5 ± 0.1 &#956;g/ml and 9.5 ± 2.6 &#956;g/ml, respectively. There were no significant differences in the plasma levels of vitamins A and E in males and females. Mean serum levels of vitamins A and E were within the normal range for both sexes. Serum lipid levels (total cholesterol, triglyceride and apoB) correlated with serum levels of vitamin E (p < 0.05). Serum levels of vitamins A and E were also correlated (p < 0.05). Standardised vitamin E levels showed significant negative correlation with most studied lipid profiles (p < 0.05). Conclusion. This study found that mean serum levels of the natural antioxidants vitamin E, and especially vitamin A, were close to the lower end of the normal range of these antioxidants in type 2 diabetics. Also, serum vitamin E and standardised vitamin E levels were important predictors of serum apoA1 levels in these patients. South African Journal of Clinical Nutrition Vol. 19(1) 2006: 39-4

Effect of melatonin ingestion on physical performance, metabolic responses, and recovery after an intermittent training session

Objectives Fatigue is a limiting factor for sport performance. For this reason, optimal recovery after training is just as critical as the training program itself, if not more. Indeed, there is a need for strategies that can facilitate recovery after training, and one such strategy is the ingestion of supplements like melatonin (MEL). This study aimed to evaluate if MEL intake could improve recovery of athletes after an intermittent training session (ITS). Methods Fifteen elite female athletes (17.4 ± 0.4 years, 76.4 ± 5.6 kg, 1.76 ± 0.04 m; mean ± standard deviation) participated in two testing campaigns. During each period, they performed a battery of physical and cognitive tests before and after an ITS, as well as after ingesting MEL (6 mg tablet) or placebo in a randomized design. The ITS comprised the modified agility T-test, squat jump, counter movement jump, maximum standing ball-throw velocity test, maximum jump ball-throw velocity test, and 20-m sprint. Oral temperature (OT) and vigilance were evaluated before and after the ITS. Rating of perceived exertion (RPE), blood lactate [La], and glucose [Gl] were recorded after each ITS. Results Short-term performance, recovery of physical performance, and OT were not affected by MEL ingestion after the ITS. Moreover, MEL did not affect cognitive performance or RPE scores after the ITS. However, [La] and [Gl] (p < 0.05 for both) were decreased after MEL ingestion. Conclusion: MEL has no effect on the recovery of physical performance but may affect glucose utilization and lactate metabolism during the team-handball training session

Time interval moderates the relationship between psyching-up and actual sprint performance

This study attempted to test whether the strongest effect of psyching-up (PU) strategy on actual sprint performance can be observed when the strategy is used immediately (or almost) before performance compared with when there is a delay between PU and performance. To do so, 16 male sprinters (age, 20.6 ± 1.3 years; body mass, 77.5 ± 7.1 kg; height, 180.8 ± 5.6 cm) were enrolled in a counterbalanced experimental design in which participants were randomly assigned to 10 sessions (2 [Experimental Condition: imagery vs. distraction] × 5 [Time Intervals: no interval, 1 minute, 2 minutes, 3 minutes, and 5 minutes]). Before performing the experimental tasks, participants rated: (a) the Hooper index, (b) their degree of self-confidence, and (c) after the completion of the experimental test; they rated their perceived effort. Findings showed that the imagery significantly improved sprint performance. Specifically, the imagery enhanced performance on the phase of acceleration (0-10 m) and on the overall sprint (0-30 m) when used immediately before performance and at 1- and 2-minute intervals but not for 3- and 5-minute intervals. These findings support the hypothesis that the potential effect of the PU strategy on performance vanishes over time. The pre-experimental task Hooper and self-efficacy indexes did not change across the 10 experimental sessions, reinforcing the view that the observed performance changes were directly caused by the experimental manipulation and not through any altered status of the athletes (self-efficacy, fatigue/recovery, and stress). The potential mechanisms underlying such a process and practical applications are discussed

Do cognitive training strategies improve motor and positive psychological skills development in soccer players? Insights from a systematic review

Soccer players are required to have well-developed physical, technical and cognitive abilities. The present systematic review, adhering to Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines, examined the effects of cognitive training strategies on motor and positive psychological skills development in soccer performance and identified the potential moderators of the “cognitive training-soccer performance” relationship. Thirteen databases were systematically searched using keywords related to psychological or cognitive training in soccer players. The review is based on 18 studies, employing 584 soccer players aged 7-39 years. Cognitive strategies, particularly imagery, appear to improve sports performance in soccer players. Regarding imagery, the combination of two different types of cognitive imagery training (i.e., cognitive general and cognitive specific) have a positive influence on soccer performance during training, whereas motivational imagery (i.e., motivational general-arousal, motivational general-mastery, and motivational specific) enhance competition performance. Younger soccer players employ cognitive general and cognitive specific imagery techniques to a greater extent than older soccer players. Combined cognitive training strategies were more beneficial than a single cognitive strategy relative to motor skills enhancement in elite (particularly midfielders) and amateur (i.e., when practicing complex and specific soccer skills in precompetitive period) soccer players. In conclusion, it appears that there are differences in cognitive/psychological training interventions, and their efficacy, according to whether they are directed towards training or competition, and the age, standard and playing position of the players

Reliability and validity of the persian version of compulsive eating scale (CES) in overweight or obese women and its relationship with some body composition and dietary intake variables

Objective: Compulsive or binge eating is a kind of disturbed eating behavior, which is mostly observed among dieting women, and is integrated with appetite disorder, and uncontrolled eating of plenty of junk food. The Compulsive Eating Scale (CES) created first by Kagan & Squires in 1984, is an eight-item self-reporting instrument that is made to measure the severity of binge eating disorder. The aim of this study was to provide the reliability and validity of the Persian version of Compulsive Eating Scale (CES) among overweight and obese women in Iran. Method: One hundred and twenty six (N = 126) overweight and obese women consented to participate in this study. We estimated the anthropometric indices, including body weight, height, waist and hip circumferences, a total body fat percentage, and visceral fat level with body analyzer all in standard situations. Then, the participants completed the CES. Next, to assess concurrent validity, Beck Depression Inventory, Spielberger anxiety scale, appetite visual analogue rating scale, Food Craving questionnaire, Three-Factor Eating Questionnaire-R18, and Restraint eating visual analogue rating scale were performed simultaneously. To assess test-retest reliability, CES was repeated for all the participants two weeks later. Moreover, we reported the internal consistency and factor analysis of this questionnaire. Furthermore, we estimated the concurrent correlation of CES with logically relevant questionnaires and body composition and anthropometric indices. Results: Based on the reliability analysis and factor analysis of the principal component by Varimax rotation, we extracted two factors: eating because of negative feelings, and overeating. Internal consistency (Cronbach's alpha) of the CES was 0.85 (Cronbach alpha of the factors was 0.85, and 0.74, respectively). The test-retest correlation of the CES was 0.89. Also, the split-half reliability of the questionnaire was established with the correlation coefficient between Sets I and II. The correlation was 0.85. Conclusion: This study provides preliminary support for the reliability and validity of the Persian version of the CES. This instrument would be helpful in measuring the clinical practice and research studies of obesity, appetite and eating disorders reliably and validly