The influence of the field orientation on physical demands in soccer small-sided games

The aim of this study was to compare the physical demands of SSG with either greater length (SSGlength) or width (SSGwidth) with official soccer matches. Sixteen Brazilian U-20 national-level soccer players participated in two sessions with SSGlength (4v4, 40 m length and 26 m width) and two sessions with SSGwidth (4v4, 26 m length and 40 m width). External and internal load variables were monitored and compared to official games (12.8 ± 8.9 games per player). Data were standardized to the time and compared between the experimental conditions by a one-way analysis of variance (ANOVA) with repeated measures (level of significance set at p < 0.05). The effect size was calculated by the partial ETA squared (ɳ p2). Results showed that the total distance covered during SSGlength was significantly higher compared to official matches (8.1%; p = 0.001) and SSGwidth (5.2%; p = 0.049). Highest values were registered in the matches when compared to SSGlength and SSGwidth for high-speed distance, sprint distance, maximal speed and number of sprints. The number of accelerations was significantly lower during official matches than SSGwidth (36.5%; p = 0.002) and SSGlength (45.0%; p < 0.001). The number of high-speed actions was higher in official games when compared to SSGwidth (47.1%; p < 0.001). No differences were found between matches and SSGlength ( p = 0.059). We concluded that the physical demands of the 4v4 SSGs adopted in this study were different from the physical demands of official match play. The use of a field with a greater width rather than length does not appear to make the physical demands of the SSG more similar to the official games.

Acute and delayed effects of strength training in ball velocity and accuracy in young competition tennis players

This study aimed to investigate the acute and delayed effects of medicine ball throws and resistance training in ball velocity and accuracy of serve, forehand and backhand in young competition tennis players. A crossover-randomized design was used with 10 competition tennis players (6 girls and 4 boys between 14 and 18 years old). The subjects performed 6 stroke test sessions, 3 for each strength protocol. The velocity and accuracy of strokes were measured before (basal situation), 3 minutes, 24 and 48 hours after the protocol. Medicine ball throws protocol was performed by accomplishing 3 sets of 6 repetitions using a 2 kg ball, throwing it at maximal speed. Resistance training protocol was performed by accomplishing 3 sets of 6 repetitions at 75% one-repetition maximum, lifting the load at maximal speed of bench press, dead lift, one hand row and half squat. There were no significant (p > 0.05) differences in all strokes, regarding ball velocity and accuracy after each method and each recovery time, compared to the basal situation. These results suggest that medicine ball throws and resistance training methods have no acute and delayed detrimental effects on stroke velocity and accuracy in young competition tennis players.

Variability of External Intensity Comparisons between Official and Friendly Soccer Matches in Professional Male Players

The aims of this study were to compare the external intensity between official (OMs) and friendly matches (FMs), and between first and second halves in the Iranian Premier League. Twelve players participated in this study (age, 28.6 ± 2.7 years; height, 182.1 ± 8.6 cm; body mass, 75.3 ± 8.2 kg). External intensity was measured by total duration, total distance, average speed, high-speed running distance, sprint distance, maximal speed and body load. In general, there was higher intensity in OMs compared with FMs for all variables. The first half showed higher intensities than the second half, regardless of the type of the match. Specifically, OMs showed higher values for total sprint distance (p = 0.012, ES = 0.59) and maximal speed (p < 0.001, ES = 0.27) but lower value for body load (p = 0.038, ES = −0.42) compared to FMs. The first half of FMs only showed lower value for body load (p = 0.004, ES = −0.38) than FMs, while in the second half of OMs, only total distance showed a higher value than FMs (p = 0.013, ES = 0.96). OMs showed higher demands of high intensity, questioning the original assumption of FMs demands. Depending on the period of the season that FMs are applied, coaches may consider requesting higher demands from their teams.

Loss of Hypoxia Signaling Limits Physiologic and Muscle Adaptations to Aerobic Exercise in Aging

To assess the differential effects of exercise with age, Young (Y, 10-12 weeks) and Old (O, 23-25 months) mice were subjected to regimented treadmill running or no regimented exercise. Y, trained mice experienced a significant increase in maximal distance running, maximal speed of running, and lean muscle mass in comparison to age-matched, untrained controls. O mice did not improve significantly in any of these measures following training. Transcriptome analysis of gastrocnemius from Y mice demonstrated differential regulation of 120 genes with exercise. None of these genes were similarly regulated in the O group. Genes most upregulated following exercise in Y mice were direct targets of the hypoxia signaling pathway. Immunoblotting demonstrated that aryl hydrocarbon receptor nuclear translocator (ARNT), a critical regulator of hypoxia signaling, increased 3-fold with exercise in Y mice, but this increase was absent in O mice following exercise. To assess whether this loss of ARNT in O muscle impaired the exercise response, we generated a mouse with inducible, skeletal muscle-specific knockout of ARNT (ARNT muscle (m) KO). Following regimented exercise, ARNT mKO mice did not improve maximal distance running, maximal running speed, or lean muscle mass in comparison to untrained ARNT mKO mice. Littermate, age-matched ARNT wild type mice increased significantly in all of these measures following training. Administration of ML228, an ARNT agonist, increased maximal running distance and speed in response to exercise training in O mice. These results suggest that restoration of ARNT and hypoxia signaling may restore the physiologic response to exercise in aging.

Luminescence of Baikal water as a dynamic background of the Baikal-GVD Neutrino Telescope

The Baikal-GVD is a neutrino telescope situated in the deepest freshwater lake in the world — Lake Baikal. The design of the Baikal-GVD trigger system allows also to study the ambient light of the lake. The analysis of the optical light activity of Baikal water, particularly, time and spatial variations of the luminescence activity for data collected in years 2018, 2019, and 2020 is presented. For the first time we observed highly luminescent layer moving upwards with maximal speed of 28 m/day in January 2021.

Development of a New Negative Obstacle Sensor for Augmented Electric Wheelchair

Due to pathologies or age-related problems, in some disabled people, motor impairment is associated with cognitive and/or visual impairments. This combination of limitations unfortunately leads to an inability to move around independently. Indeed, their situation does not allow them to use a conventional electric wheelchair, for safety reasons, and for the moment there is no other technological solution providing safe movement capacity. This lack of access to an autonomous travel solution has the consequence of weakening the intellectual, personal, social, cultural and moral development, as well as the life expectancy, of the people concerned. In this context, our team is working on the development of an optoelectronic system that secures the displacement of electric wheelchairs. This is a large project that requires the development of several functionalities such as: the anti-collision of the wheelchair with its environment, the prevention of falls from the wheelchair on uneven levels, and the adaptation of the system mechanically and electronically to the majority of commercially available electric wheelchair models, among others. In this article, we introduce our solution for detecting dangerous height differences, also called “negative obstacles”, through the creation of a dedicated sensor. This sensor works by optical triangulation and can embed several laser beams in order to extend its detection zone. It has the particularity of being robust in direct sunlight and rain and has a sufficiently high measurement rate to be suitable for the displacement of electric wheelchairs. We develop an adapted algorithm, and point out compromises, in particular between the orientation of the laser beams and the maximal speed of the wheelchair.

From Maximal Force to the Field Equations of General Relativity

We point out that field equations of general relativity are implied by a maximal force given by c4/4G, analogous to the way that special relativity is implied by a maximal speed given by c. We present some of the arguments for this equivalence. The maxi-mal force naturally plays the role of an elastic constant for space-time. Implications of the maximal force for gravitational wave measurements, cosmology and black holes are highlighted. Quantum aspects of the maximal force are discussed.

Determining the Prognostic Validity of the Unilateral Horizontal Cyclic Jumps Test in Sprint Performance

In sports practice, motor tests are commonly used to predict success in specific segments of sprint running, as well as post-injury tests in rehabilitation. The purpose of this analytical cross-sectional study was to determine the prognostic validity of the unilateral horizontal cyclic jumps for a 20 m (UHCJ20m) test on sprint running success. A sample of 118 kinesiology students aged 20.5 ± 1.2 years with an average height of 179.7 ± 6.4 cm and a body mass of 75.6 ± 7.3 kg was used to determine the correlation between the results of the UHCJ20m test and the results of the 20 m sprint start run (MRLS20m), the 20 m sprint flying start run (MRFS20m), and the 100 m run (M100m). The results showed a moderate correlation in all tests (MRLS20m (R = 0.49), MRFS20m (R = 0.53), and M100m (R = 0.38)) with UHCJ20m. In addition to the final result, the multiple regression analysis showed a significant moderate correlation between the kinematic parameters of the UHCJ20m test and the results in the MRLS20m (R = 0.38), MRFS20m (R = 0.49), and M100m (R = 0.37) tests. The stride length (SL) and the contact time (CT) of the UHCJ20m test were statistically significant predictors for the 100 m sprint, the number of steps for MRLS20m, and the SL and the CT for MRFS20m sprint success. Unilateral horizontal cyclic jumps are a significant predictor of success in sprint running, especially for the maximal speed running segment.

Oxidative phenotype induced by aerobic physical training prevents the obesity-linked insulin resistance without changes in gastrocnemius muscle ACE2-Angiotensin(1-7)-Mas axis

Background We investigate the effect of aerobic physical training (APT) on muscle morphofunctional markers and Angiotensin Converting Enzyme 2/Angiotensin 1-7/Mas receptor (ACE2/Ang 1-7/Mas) axis in an obesity-linked insulin resistance (IR) animal model induced by cafeteria diet (CAF). Methods Male C57BL/6J mice were assigned into groups CHOW-SED (chow diet, sedentary; n = 10), CHOW-TR (chow diet, trained; n = 10), CAF-SED (n = 10) and CAF-TR (n = 10). APT consisted in running sessions of 60 min at 60% of maximal speed, 5 days per week for 8 weeks. Results Trained groups had lower body weight and adiposity compared with sedentary groups. CAF-TR improved the glucose and insulin tolerance tests compared with CAF-SED group (AUC = 28.896 ± 1589 vs. 35.200 ± 1076 mg dL−1 120 min−1; kITT = 4.1 ± 0.27 vs. 2.5 ± 0.28% min−1, respectively). CHOW-TR and CAF-TR groups increased exercise tolerance, running intensity at which VO2 max was reached, the expression of p-AMPK, p-ACC and PGC1-α proteins compared with CHOW-SED and CAF-SED. Mithocondrial protein expression of Mfn1, Mfn2 and Drp1 did not change. Lipid deposition reduced in CAF-TR compared with CAF-SED group (3.71 vs. 5.53%/area), but fiber typing, glycogen content, ACE2 activity, Ang 1-7 concentration and Mas receptor expression did not change. Conclusions The APT prevents obesity-linked IR by modifying the skeletal muscle phenotype to one more oxidative independent of changes in the muscle ACE2/Ang 1-7/Mas axis.

The evolutionary biomechanics of locomotor function in giant land animals

ABSTRACT Giant land vertebrates have evolved more than 30 times, notably in dinosaurs and mammals. The evolutionary and biomechanical perspectives considered here unify data from extant and extinct species, assessing current theory regarding how the locomotor biomechanics of giants has evolved. In terrestrial tetrapods, isometric and allometric scaling patterns of bones are evident throughout evolutionary history, reflecting general trends and lineage-specific divergences as animals evolve giant size. Added to data on the scaling of other supportive tissues and neuromuscular control, these patterns illuminate how lineages of giant tetrapods each evolved into robust forms adapted to the constraints of gigantism, but with some morphological variation. Insights from scaling of the leverage of limbs and trends in maximal speed reinforce the idea that, beyond 100–300 kg of body mass, tetrapods reduce their locomotor abilities, and eventually may lose entire behaviours such as galloping or even running. Compared with prehistory, extant megafaunas are depauperate in diversity and morphological disparity; therefore, turning to the fossil record can tell us more about the evolutionary biomechanics of giant tetrapods. Interspecific variation and uncertainty about unknown aspects of form and function in living and extinct taxa still render it impossible to use first principles of theoretical biomechanics to tightly bound the limits of gigantism. Yet sauropod dinosaurs demonstrate that &gt;50 tonne masses repeatedly evolved, with body plans quite different from those of mammalian giants. Considering the largest bipedal dinosaurs, and the disparity in locomotor function of modern megafauna, this shows that even in terrestrial giants there is flexibility allowing divergent locomotor specialisations.