Seasonal dynamics of macrophyte abundance in two regulated streams

This study analysed seasonal dynamics of macrophyte abundance in two perennial lowland regulated streams (Stream 1 and 2) in the Danube basin (Slovakia). Assessments of macrophyte abundance and environmental characteristics were accomplished 7 times during the vegetation period in 2005 within a 100 m long section. Statistically significant differences in total abundance of macrophytes as well as an abundance of macrophyte groups (hydrophytes, amphiphytes, helophytes) and Potamogeton nodosus were detected among months within the vegetation period. Abundance fluctuations for individual macrophyte groups and species were moderate in Stream 1 and much stronger in Stream 2. Only amphiphytes showed bimodal temporal distribution in Stream 1, but the abundance of this group was low, reflecting more or less random occurrence of species in vegetation period. Multiple linear regression revealed that water depths and air temperature are the most significant environmental variables affecting the seasonal pattern of total as well as dominating group abundance in Stream 1 and 2, respectively. In all cases, abundances are significantly influenced by the abundance of the respective group in the preceding month. Culmination time differed between streams for all macrophyte groups except helophytes. Total abundance culminated 0.57 month later in the Stream 1 compared to Stream 2.     

Players’ physical performance in LaLiga across the season: insights for competition continuation after COVID-19

Due to the COVID-19 outbreak, professional football players competing in LaLiga were confined at home for ~8 weeks and then they were allowed to train to prepare the first competitive match for 4 weeks. As the duration of summer break in the prior four seasons of LaLiga (from 2015-2016 to 2018-2019) was of similar length to the suspension of the championship due to COVID-19 (~12 weeks), we have analysed the running performance of teams competing in LaLiga in these four seasons to anticipate players’ physical performance after the resumption of the competition. The analysis includes the average running distance per game for each of the 38 matchdays that compose LaLiga. One-way ANOVA revealed that there was a main effect of the matchday on total running distance per match (p = 0.001), and in the distance covered between 14.0 and 20.9 km/h (p < 0.001), between 21.0 and 23.9 km/h (p < 0.001) and at above 24.0 km/h (p < 0.001). Overall, the post-hoc analysis revealed that the running patterns progressively increased during the first 8-10 matchdays and then reached a plateau which was significantly different to matchday-1 (p < 0.05). This analysis reveals that, in the prior four competitive seasons of LaLiga, players’ physical performance was lower at the beginning of the season and the teams needed approximately 8-10 matchdays to reach a steady state running performance. These data suggest that football players will progressively increase their performance across the 11 matchdays remaining to complete LaLiga.     

Mechanical energy contribution of the metatarsophalangeal joint to running and sprinting

Despite the fact that a number of studies have investigated lower extremity energy generation during locomotion, the influence of the metatarsophalangeal (MP) joint remained unknown. The purpose of this study was to determine the relative contribution of the MP joint to the total mechanical energy in running and sprinting. A sagittal plane analysis was performed on data collected from 10 trained male athletes (five runners and five sprinters). The MP moment was assumed to be negligible until the ground reaction force acted distal to the joint. During running, once the ground reaction force crossed the MP joint, the MP moment was plantarflexor for the remainder of ground contact with average peak values of 59.9 Nm. The MP joint moment was plantarflexor throughout the stance phase for sprinting with average peak values of 112.4 Nm. Since the MP joint was dorsiflexing throughout the majority of the stance phase the joint absorbed large amounts of energy, on average 20.9 J during running and 47.8 J during sprinting. A lack of plantarflexion of the MP joint resulted in a lack of energy generation during take-off. Thus, the energy that was absorbed at the joint was dissipated in the shoe and foot structures.