Screen media usage, sleep time and socio-demographic features are related to adolescents' academic performance, but interrelations are little explored. This paper describes these interrelations and behavioral profiles clustered in low and high academic performance. A nationally representative sample of 3,095 Spanish adolescents, aged 12 to 18, was surveyed on 15 variables linked to the purpose of the study. A Self-Organizing Maps analysis established non-linear interrelationships among these variables and identified behavior patterns in subsequent cluster analyses. Topological interrelationships established from the 15 emerging maps indicated that boys used more passive videogames and computers for playing than girls, who tended to use mobile phones to communicate with others. Adolescents with the highest academic performance were the youngest. They slept more and spent less time using sedentary screen media when compared to those with the lowest performance, and they also showed topological relationships with higher socioeconomic status adolescents. Cluster 1 grouped boys who spent more than 5.5 hours daily using sedentary screen media. Their academic performance was low and they slept an average of 8 hours daily. Cluster 2 gathered girls with an excellent academic performance, who slept nearly 9 hours per day, and devoted less time daily to sedentary screen media. Academic performance was directly related to sleep time and socioeconomic status, but inversely related to overall sedentary screen media usage. Profiles from the two clusters were strongly differentiated by gender, age, sedentary screen media usage, sleep time and academic achievement. Girls with the highest academic results had a medium socioeconomic status in Cluster 2. Findings may contribute to establishing recommendations about the timing and duration of screen media usage in adolescents and appropriate sleep time needed to successfully meet the demands of school academics and to improve interventions targeting to affect behavioral change.

Fibromyalgia (FM) is a chronic syndrome characterized by widespread pain and other physical and psychological features. In this study, we aimed to analyze the effect of a low-intensity physical exercise (PE) program, combining endurance training and coordination, on psychological aspects (i.e., pain catastrophizing, anxiety, depression, stress), pain perception (i.e., pain acceptance, pressure pain threshold (PPT), and quality of life and physical conditioning (i.e., self-perceived functional capacity, endurance and functional capacity, power and velocity) in women with FM. For this purpose, a randomized controlled trial was carried out. Thirty-two women with FM were randomly allocated to a PE group (PEG, n = 16), performing an eight-week low-intensity PE program and a control group (CG, n = 16). Pain catastrophizing, anxiety, depression, stress, pain acceptance, PPT, quality of life, self-perceived functional capacity, endurance and functional capacity, power, and velocity were assessed before and after the intervention. We observed a significant improvement in all studied variables in the PEG after the intervention (p < 0.05). In contrast, the CG showed no improvements in any variable, which further displayed poorer values for PPT (p < 0.05). In conclusion, a low-intensity combined PE program, including endurance training and coordination, improves psychological variables, pain perception, quality of life, and physical conditioning in women with FM.

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Study design: Cross-sectional validation study. Objectives: The goals of this study were to validate the use of accelerometers by means of multiple linear models (MLMs) to estimate the O 2 consumption (VO 2 ) in paraplegic persons and to determine the best placement for accelerometers on the human body. Setting: Non-hospitalized paraplegics' community. Methods: Twenty participants (age ¼ 40.03 years, weight ¼ 75.8 kg and height ¼ 1.76 m) completed sedentary, propulsion and housework activities for 10 min each. A portable gas analyzer was used to record VO 2 . Additionally, four accelerometers (placed on the non-dominant chest, non-dominant waist and both wrists) were used to collect second-by-second acceleration signals. Minute-byminute VO 2 (ml kg À1 min À1 ) collected from minutes 4 to 7 was used as the dependent variable. Thirty-six features extracted from the acceleration signals were used as independent variables. These variables were, for each axis including the resultant vector, the percentiles 10th, 25th, 50th, 75th and 90th; the autocorrelation with lag of 1 s and three variables extracted from wavelet analysis. The independent variables that were determined to be statistically significant using the forward stepwise method were subsequently analyzed using MLMs. Results: The model obtained for the non-dominant wrist was the most accurate (VO 2 ¼ 4.0558 À0.0318Y 25 þ 0.0107Y 90 þ 0.0051 Y ND2 À0.0061Z ND2 þ 0.0357VR 50 ) with an r-value of 0.86 and a root mean square error of 2.23 ml kg À1 min À1 . Conclusions: The use of MLMs is appropriate to estimate VO 2 by accelerometer data in paraplegic persons. The model obtained to the non-dominant wrist accelerometer (best placement) data improves the previous models for this population.

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The relationship among physical activity, physical fitness and academic achievement in adolescents has been widely studied; however, controversy concerning this topic persists. The methods used thus far to analyse the relationship between these variables have included mostly traditional lineal analysis according to the available literature. The aim of this study was to perform a visual analysis of this relationship with self-organizing maps and to monitor the subject's evolution during the 4 years of secondary school. Four hundred and forty-four students participated in the study. The physical activity and physical fitness of the participants were measured, and the participants' grade point averages were obtained from the five participant institutions. Four main clusters representing two primary student profiles with few differences between boys and girls were observed. The clustering demonstrated that students with higher energy expenditure and better physical fitness exhibited lower body mass index (BMI) and higher academic performance, whereas those adolescents with lower energy expenditure exhibited worse physical fitness, higher BMI and lower academic performance. With respect to the evolution of the students during the 4 years, ∼25% of the students originally clustered in a negative profile moved to a positive profile, and there was no movement in the opposite direction.

The main objective of this study was to examine the effect of different judo training loads on heart rate variability (HRV) measurements, to determine if they can be used as valid indicators in monitoring stress and recovery in judo athletes. Fourteen male national-standard judo athletes were randomly divided into 2 groups, and each group followed a different type of training, namely, a high training load (HTL) and a moderate training load program (MTL). Data collection included HRV measurements, a Recovery Stress Questionnaire for athletes (RESTQ-SPORT), and strength measurements, 4 weeks before and after the training program. The HTL group had lower square root of the mean squared difference of successive RR intervals, very low frequency, high frequency, short-term variability, short-range scaling exponents, general recovery, sport-specific recovery, general stress, maximum strength, maximum power, and higher low/high frequency ratio at posttest compared with pretest (p ≤ 0.05). The HTL group showed lower short-range and long-range scaling exponents, general recovery, sport-specific recovery, and higher general stress than the MTL group in posttest measurements (p ≤ 0.05). In conclusion, judo athletes enrolled in an HTL program showed an imbalance of the autonomic nervous system with decreased vagal modulation, together with a decrease in strength parameters, higher markers for stress, and a lower perception of recovery.

Study design: Time series design. Objectives: To determine the effects of a shoulder resistance training programme on isokinetic and isometric strength, body composition, pain and functionality in paraplegic subjects. Setting: University of Valencia, Valencia, Spain. Methods: A total of 15 subjects with thoracic spinal cord injury (SCI) performed three testing sessions with an 8-week period between the sessions. Subjects were not disturbed between the first and the second testing sessions. Subjects performed an 8-week resistance training programme after the second testing session. Variations in isometric and isokinetic shoulder muscle strength, body composition, reported pain and shoulder functionality were evaluated. Results: The training programme produced a significant increase (Po0.05) in the isometric and isokinetic strength of several shoulder movements as well as an increase (Po0.05) in arm fat-free mass and a decrease in arm fat mass (FM). Furthermore, reported pain was decreased, (Po0.05) and upper-limb functionality was increased (Po0.05). Conclusion: Implementing resistance training programmes as physical therapy in SCI subjects effectively increases strength, muscle mass and upper-limb functionality, whereas decreasing FM and pain perception.