Acute Effects of Intermittent Physical Activity on Perceptions of Exercise-Related Fatigue in Children

Purpose: To investigate the acute effects of intermittent activity performed at varying intensities on the perceptions of exercise-related fatigue in children. Methods: A total of 30 children completed 4 experimental conditions in random order, which consisted of 8 hours of sitting interrupted with 20 two-minute low-, moderate-, or high-intensity activity breaks or 20 two-minute sedentary breaks. The perceptions of exercise-related fatigue were determined via the Subjective Exercise Experience Scale at the beginning (0 breaks), middle (after 10 breaks), and end (after 20 breaks) of each condition. Results: The average heart rate was significantly higher with increasing exercise intensity (sedentary: 89.6 ± 1.2 beats/min, low: 114.6 ± 1.8 beats/min, moderate: 147.2 ± 1.8 beats/min, and high: 172.3 ± 1.8 beats/min, P < .0001). There was no significant main effect of condition (sedentary: −0.5 ± 0.6, low: −1.0 ± 0.7, moderate: −0.2 ± 0.5, and high: −0.6 ± 1.2; P = .86) and time (10–0 breaks: −0.7 ± 0.5 and 20–0 breaks: −0.5 ± 0.5; P = .45), nor time by condition interaction (P = .99) on change in exercise-related fatigue. Conclusions: Incorporating intermittent activity into physical activity programs may help to reduce barriers to regular exercise by minimizing perceptions of exercise-related fatigue in children.

Perfil de entrenamiento y rendimiento en bodyboarders de élite

El surf puede considerarse una actividad intermitente, con el nivel de condición física a contribuir para un mejor rendimiento tanto en el entrenamiento como en la competición. A pesar de algunos conocimientos sobre los niveles de aptitud de los surfistas de élite, la investigación que examina el perfil de entrenamiento de Bodyboarders de elite y su influencia en los resultados de la competición es limitada. Durante el Viana World Bodyboard Pro, 49 bodyboarders de élite respondieron un cuestionario retrospectivo. La correlación de Spearmen y la prueba de Mann-Whitney se aplicaron para determinar posibles asociaciones y comparaciones entre grupos. La clasificación final en lo circuito mundial está influenciada por la práctica de Entrenamiento Físico y tener entrenador (p<0.05). El bodyboard es más que un deporte recreativo que necesita una nueva visión sobre la planificación específica. Especialmente para atletas junior, el entrenamiento físico es un factor clave para lograr un mejor rendimiento. Surfing can be considered an intermittent activity with different intensities, were fitness level of surfing athletes contributes to a better performance in both training and competition. Despite some knowledge about the fitness levels of elite surfers, there is limited published research examining the training profile of elite Bodyboarders and is influence in competition outcomes. During the Viana World Bodyboard Pro in Viana do Castelo, 49 elite bodyboarders, replied a retrospective questionnaire that include training habits. Spearmen correlation and Mann-Whitney test was applied to determine possible associations and comparation between groups. The ending ranking in the world tour is influenced by the practice of Physical Training and the fact that have a coach (p< 0.05). Bodyboarding is more than a recreational sport needing a new insight regarding sports specific season plan, that allow athletes compete at higher level. Specially for Junior athlete’s, physical training is key factor for accomplish better performance.

Static and dynamic reliability of WIMU PRO™ accelerometers according to anatomical placement

Currently, the use of accelerometry to analyze training and competition is on the increase. Thus, accelerometers must be reliable when calculating different variables from raw data. The purpose of this investigation was to assess the reliability of triaxial accelerometers that contain inertial devices for measuring external loads in sports. Four and eight WIMU PRO™ inertial devices (RealTrack Systems, Almeria, Spain) were assessed in laboratory and specific sport conditions, respectively. The laboratory test was performed in static (with and without stress) and dynamic (10 and 30 Hz vibrations) conditions. In addition, two tests were performed during continuous and intermittent activity: (1) an incremental progressive running test on the treadmill and (2) 5 min of a Soccer-Specific Aerobic Field Test (SAFT90), where the devices were placed on ankle, knee, lower back and scapulae. Direct assessment of the accelerometers by calculating a vector magnitude, expressed as total acceleration (AcelT), was used for reliability using bias, ±95% limits of agreement and coefficient of variation. A t-test and Pearson’s r were performed for test–retest reliability. In the laboratory assessments, an excellent within- and between-device static (with and without stress) and dynamic reliability were found (coefficient of variation = 0.23%–0.78%). A very high reliability was also observed in the incremental treadmill test (coefficient of variation = 2.20%) and SAFT90 (coefficient of variation = 2.96%) with a nearly perfect correlation between devices ( r = 0.99–1.00). Finally, in the between-sessions reliability analysis, excellent results ( p = 0.46–0.98; t = 0.01–0.73) and a very strong correlation ( r = 0.86–0.96) was found with p values greater than 0.05 indicating no differences between the tests. In conclusion, the accelerometers of the tested device have shown excellent results for within- and between-device reliability and in test–retest analysis. Thus, this device can calculate all variables that depend on accelerometry measurement such as PlayerLoad™ or impacts in different ranges, and in different anatomical locations.

Acute Compensatory Responses to Interrupting Prolonged Sitting With Intermittent Activity in Preadolescent Children

Purpose: The purpose of this study was to compare the effects of intermittent activity performed at varying intensities and of prolonged sitting on physical activity compensation. Methods: A total of 33 children (14 boys and 19 girls; age 7–11 y; 24% overweight/obese; 61% nonwhite) completed 4 experimental conditions in random order: 8 hours of sitting interrupted with 20 two-minute low-, moderate-, or high-intensity activity breaks or 20 two-minute sedentary computer game breaks. Physical activity energy expenditure (PAEE) was assessed via accelerometry to establish baseline PAEE and throughout each condition day (8-h in-lab PAEE, out-of-lab PAEE, and 3-d postcondition). Results: Compared with baseline PAEE, total daily PAEE was significantly higher during the high-intensity condition day (153 ± 43 kcal, P = .03), unchanged during the low-intensity (−40 ± 23 kcal, P > .05) and moderate-intensity condition days (−11 ± 18 kcal, P > .05), and decreased in response to prolonged sitting (−79 ± 22 kcal, P = .03). There were no significant differences in PAEE 3-day postcondition across conditions (P > .05). Conclusion: Despite the varying levels of PAEE accumulated during the 8-hour laboratory conditions, out-of-lab PAEE during each condition day and 3-day postcondition did not change from the baseline. These findings provide preliminary evidence that spontaneous physical activity in children does not change in response to intermittent activity or prolonged sitting.

High-Intensity Warm-Ups: Effects During Subsequent Intermittent Exercise

High-intensity, short-duration warm-up techniques improve acute physical performance, but sparse research has examined their consequence when followed by intermittent activity, which is pertinent to team sports. The authors compared a 5-repetition-maximum (5RM) leg-press, a small-sided game (SSG), and a current team-sport warm-up in 10 semiprofessional soccer players after 2 intermittent-activity protocols consisting of 15 repetitions of a 60-s circuit that included sprinting, slalom, walking, jogging, decelerations, changes of direction, backward running, and striding activities. There was a large improvement in countermovement-jump height in the 5RM after the 1st intermittent-activity protocol (mean, ±90% CL 6.0, ±4.0%, P = .03) and a small improvement after the 2nd (4.6, ±4.0%, P = .04) compared with team sport. Reactive agility was moderately faster via 5RM after the 1st intermittent-activity protocol (3.1, ±2.6%: P = .04) and the 2nd (5.7, ±2.7%, P = .001) than via SSG. There was a small improvement in reactive agility after the 1st intermittent-activity protocol in the 5RM, compared with team sport (3.3, ±2.9%, P = .04). There was a small improvement in mean 20-m-sprint times after both intermittent-activity protocols in the 5RM, compared with SSG (4.2, ±2.0%, P = .01, and 4.3, ±2.0%, P = .01) and, after the 1st intermittent-activity protocol only, compared with team sport (4.2, ±2.1%, P = 0.02). Small increases in blood lactate concentration were observed (46.7, ±18.6%, P = .01) in the 5RM compared with the SSG after the 2nd intermittent-activity protocol. Improved performances after the 5RM warm-up should encourage practitioners to reduce activity time and include high-intensity tasks in team-sport warmups aimed at inducing a potentiating effect.