Analysis of Differences in Running Demands between Official Matches and Transition Games of Young Professional Soccer Players according to the Playing Position

The aim of this study was to compare the running demands of transition games (TGs) and official matches, analysing their requirements according to the performance of each position. An observational design was used to examine the activity of 20 soccer players during official matches and TGs. GPS technology was used to monitor the total distance covered (DC), distance at speeds between 14-17.9 km•h-1, 18-21 km•h-1, and above 21 km•h-1, peak speed, accelerations and decelerations above 2.5 m•s-2, and Player Load for both activities. All players were assigned to groups: centre-backs (CBs), fullbacks (FBs), defensive midfielders (DMFs), offensive midfielders (OMFs), wide midfielders (WMFs) and strikers (Ss). TGs showed greater total DC, DC 14-17.9 km•h-1, DC 18-21 km•h-1, DC >21 km•h-1, accelerations and decelerations >2.5 m•s-2, and Player Load (p < 0.01). CBs, FBs and Ss showed more DC, DC 14-17.9 km•h-1, DC 18-21 km•h-1, DC >21 km•h-1, accelerations and decelerations >2.5 m•s-2 and Player Load in TGs (p < 0.01). In the midfielder positions, transition game players showed greater DC 18-21 km•h-1, DC >21 km•h-1, accelerations and decelerations >2.5 m•s-2 than in matches (p < 0.05). DMFs showed higher total DC (p < 0.05) and WMFs greater DC and DC 14-17.9 km•h-1 (p < 0.01) in these drills. During transition games CBs showed greater DC 14-17.9 km•h-1 than FBs, and greater DC than Ss (p < 0.05). FBs performed more decelerations >2.5 m•s-2 than DMFs and OMFs (p < 0.05). TGs produced a homogenized load in soccer players, independent of their position, which exceeded the external load of official matches.

Concurrent validity and between-unit reliability of a foot-mounted inertial measurement unit to measure velocity during team sport activity

The concurrent validity and between-unit reliability of a foot-mounted inertial measurement unit (F-IMU) was investigated during linear and change of direction running drills. Sixteen individuals performed four repetitions of two drills (maximal acceleration and flying 10 m sprint) and five repetitions of a multi-directional movement protocol. Participants wore two F-IMUs (Playermaker) and 10 retro-reflective markers to allow for comparisons to the criterion system (Qualisys). Validity of the F-IMU derived velocity was assessed via root-mean-square error (RMSE), 95% limits of agreement (LoA) and mean difference with 95% confidence interval (CI). Between-unit reliability was assessed via intraclass correlation (ICC) with 90% CI and 95% LoA. The mean difference for instantaneous velocity for all participants and drills combined was -0.048 ± 0.581 m ∙ s^-1, the LoA were from -1.09 to -1.186 m ∙ s^-1 and RMSE was 0.583 m ∙ s^-1. The ICC ranged from 0.84 to 1, with LoA from -7.412 to 2.924 m ∙ s^-1. Differences were dependent on the reference speed, with the greatest absolute difference (-0.66 m ∙ s^-1) found at velocities above 7 m ∙ s^-1. Between-unit reliability of the F-IMU ranges from good to excellent for all locomotor characteristics. Playermaker has good agreement with 3D motion capture for velocity and good to excellent between-unit reliability.

Effects of internal exposure to neutron-activated 56MnO2 powder on locomotor activity in rats

At the detonation of the atomic bombing in Hiroshima and Nagasaki, a significant amount of radionuclides was produced by the neutron induced activation. The residual radiation from the explosion is crucial to the health risk of the people who entered these cities after the bombing and might have inhaled these radioactive materials. Because 56Mn is one of the major radionuclides produced in soil and have not been studied until now, we had conducted a series of experiments using rats to investigate the biological impacts of exposure of 56MnO2 particles. In these experiments, the rats' spontaneous locomotor activity was also assessed to examine the possible effects of 56Mn on their behavior. However, the locomotor activity data obtained from an individual experiment failed to identify radiation effects due to the large variation among animals and the small sample size. In the present study, all available data from our previous studies on 56MnO2 exposure (0.02-0.15 Gy of whole-body doses) as well as 60Co-γ exposure (at 2-5 Gy of whole-body doses) were pooled. Our statistical method, which takes into account individual differences and daily fluctuations, successfully identified a decrease in locomotor activity caused by 56MnO2 exposure, where the changes were gradual and reached the maximum reduction around 2 weeks after exposure. In contrast, exposure to 60Co-γ rays produced the highest decline of activity within one day. These results suggest that internal exposure to 56Mn at whole-body doses of even less than 0.15 Gy may have a long-lasting impact on locomotor activity.

Monitoring Elite Soccer Players' External Loads Using Real-Time Data

PURPOSE

To assess the validity of measuring locomotor activities and PlayerLoad using real-time (RT) data collection during soccer training.

METHODS

Twenty-nine English soccer players participated. Each player wore the same MEMS device (Micromechanical Electrical Systems; S5, Optimeye; CatapultSports, Melbourne, Australia) during 21 training sessions (N = 331 data sets) in the 2015-16 and 2016-17 seasons. An RT receiver (TRX; Catapultsports, Melbourne, Australia) was used to collect the locomotor activities and PlayerLoad data in RT and compared with the postevent downloaded (PED) data. PlayerLoad and locomotor activities (total distance covered; total high-speed running distance covered, >5.5#x00A0;m/s; total sprinting distance covered, >7 m/s; maximum velocity) were analyzed.

RESULTS

Correlations were near perfect for all variables analyzed (r = .98-1.00), with a varied level of noise between RT and PED also (0.3-9.7% coefficient of variation).

CONCLUSIONS

Locomotor activities and PlayerLoad can use both RT and PED concurrently to quantify a player's physical output during a training session. Caution should be taken with higher-velocity-based locomotor activities during RT compared to PED.

Varied behavioral responses induced by morphine in the tree shrew: a possible model for human opiate addiction

Tree shrews represent a suitable animal model to study the pathogenesis of human diseases as they are phylogenetically close to primates and have a well-developed central nervous system that possesses many homologies with primates. Therefore, in our study, we investigated whether tree shrews can be used to explore the addictive behaviors induced by morphine. Firstly, to investigate the psychoactive effect of morphine on tree shrews’ behavior, the number of jumping and shuttling, which represent the vertical and horizontal locomotor activity respectively, was examined following the injection of different dosage of morphine. Our results showed intramuscular (IM) injection of morphine (5 or 10 mg/kg) significantly increased the locomotor activity of tree shrews 30–60 min post-injection. Then, using the conditioned place preference/aversion (CPP/CPA) paradigm, we found morphine-conditioned tree shrews exhibited place preference in the morphine-paired chamber on the test day. In addition, naloxone-precipitated withdrawal induced place aversion in the chronic morphine-dependent tree shrews. We evaluated the craving for morphine drinking by assessing the break point that reflects the maximum effort animals will expend to get the drug. Our data showed the break point was significantly increased when compared to the baseline on the 1st, 7th and 14th day after the abstinence. Moreover, in the intravenous morphine self-administration experiment, tree shrews conditioned with morphine responded on the active lever significantly more frequently than on the inactive lever after training. These results suggest that tree shrew may be a potential candidate for study the addictive behaviors and the underling neurological mechanisms.