Relationship between Isokinetic Knee Strength and Speed, Agility, and Explosive Power in Elite Soccer Players

The aim of this study was to determine the relationship between the isokinetic characteristics of knee extensors and flexors with selected motor abilities: Speed, agility, and explosive power of lower extremities of professional football players in the preparation period of a yearly training cycle. Twenty-one players (age: 24.5 ± 3.9 years; body mass: 76.7 ± 4.7 kg and body height: 183.5 ± 5.5 cm) playing in the highest Polish soccer league participated in the study. The isokinetic concentric torque of the knee extensors and flexors was measured at 300°/s, 180°/s, and 60°/s velocities. Sprint performance was assessed in the 30 m sprint test (standing start). The forward, lateral, and backward movements were assessed using the T-Test of agility. Explosive power was quantified by performing the squat jump (SJ) and countermovement (CMJ), using the force platform. Due to sport-specific demands of soccer activities measured in this experiment, the relationships between peak torque (PT) and the 30 m sprint, T-Test of agility, and power of vertical jumps (SJ and CMJ) were low or medium at speeds of 60°/s and 300°/s. One of the main reasons for the lack of high dependence of the above-mentioned factors are that the measurements were performed during the initial training period where the level of individual abilities is at a low level. Additionally, this experiment may also indicate that the measurement of isokinetic knee flexion and extension peak is effective when performed at the correct angular velocity in relation to the evaluation of the intended motion structure.

Levels of Agreement for the Direction of Inter-Limb Asymmetry during Four Simple Change-of-Direction Tests in Young Male Handball Players: A Pilot Study

The purpose of this pilot study was to investigate the effects of change-of-direction (CoD) angle (90° vs. 180°) and the inclusion of acceleration approach on total task time, CoD deficit, and agreement regarding inter-limb asymmetry direction across CoD tasks. The sample included 13 young male handball players (age: 22.4 ± 3.2 years). The CoD tasks were performed over a 10 m distance with 90° and 180° turns. Both CoD tasks were performed under two conditions: (1) from the standing start and, (2) with a 10 m prior acceleration approach. Linear sprint times over a 10 m distance were also recorded for the purpose of determining the CoD deficit. The differences between the outcomes of different test variants were assessed with pairwise t-tests and associated Cohen’s d effect size. The agreement in terms of inter-limb asymmetry direction was assessed descriptively, using percentage of agreement. Results showed that the inclusion of the 10 m approach reduced the total task time (mean differences ranging between 0.26 and 0.35 s; d = 2.27–4.02; p < 0.002). The differences between 90° and 180° turn times were statistically significant under both conditions: (a) without approach (0.44–0.48 s; d = 4.72–4.84; all p < 0.001), and (b) with approach (0.50–0.54 s; d = 4.41–5.03; p < 0.001). The agreement regarding inter-limb asymmetry direction among the tasks was 30.7–61.5%. The differences between the tasks could be explained by the angle–velocity trade-off. The results of this study imply that the CoD tasks should not be used interchangeably when assessing inter-limb asymmetries.

Exploring Performances of Electric Micro-Mobility Vehicles and Behavioural Patterns of Riders for In-Depth Accident Analysis

(1) Background: Electric micro-mobility vehicles (i.e., e-bikes and e-scooters) represent a fast-growing portion of the circulating fleet, leading to a multiplication of accident cases also attributable to risky behaviours adopted by the riders. Still, data on vehicle performance and rider behaviour are sparse and difficult to interpret (if not unavailable). Information regarding the overall accident dynamics can, however, aid in identifying users’ risky riding behaviour that actually led to a harmful event, allowing one to propose efficient strategies and policies to reduce the occurrence of road criticalities. (2) Methods: Speed and acceleration data of six cyclists of traditional and electric bikes were extracted from six closed-circuit experiments and real road tests performed in the city of Florence (Italy) to derive their behavioural patterns in diverse road contexts. (3) Results: The application of analysis of variance and linear regression procedures to such data highlights differences between men and women in terms of performance/behaviour in standing start; additionally, the use of e-bikes favours a higher speed ride in correspondence to roundabouts and roads with/without the right of way. To thoroughly assess the rider’s responsibilities in an eventual accident, an ancillary procedure was highlighted to evaluate whether a micro-mobility vehicle complies with the applicable regulations. (4) Conclusion: With these results, the prospective recognition of rider behaviour was facilitated during the investigation process, and the abilities to extract such relevant information from in-depth accident data wereconsequently enhanced.

The Occurrence of Different Vertical Jump Types in Basketball Competition and their Relationship with Lower-Body Speed-Strength Qualities.

Jumps occur frequently in basketball and can be executed from a single-leg take-off following a run-up or bilaterally from a standing start. Understanding the type of jumps performed in competition and how different muscular qualities influence their performance, informs training prescription. Firstly, to quantify the occurrence of different jump types performed in competition an analysis of 15 semi-professional basketball games was undertaken. Secondly, to understand the influence of muscular qualities on performance of different jump types, Semi-professional male basketball players (N=17) performed jump tests; standing vertical jump, running vertical jumps with a double leg take-off (RVJ2) and a single leg take-off (RVJ1) and tests of lower-body speed-strength; reactive strength index (RSI) from a drop jump, counter movement jump (CMJ) and squat jump. A stationary approach was employed for 69%, a running approach for 26% and a one-step approach for 5%. RVJ1 displayed non-significant (P=0.07) moderate correlation with jump height attained from the CMJ (r=0.439) and a very large (r =.806) significant (P<0.01) correlation with RSI. Most jumps were executed from a stationary start with a bilateral take-off while a run-up occurred prior to a substantial proportion of jumps. Jumps with a single-leg take-off from a run-up strongly correlate with RSI.

Balloons on the battlefield: REBOA implementation in the UK Defence Medical Services

Established in 2018, the Defence Endovascular Resuscitation (DefER) group recognised that resuscitative endovascular balloon occlusion of the aorta (REBOA) offered an option to improve survival in battle casualties dying from haemorrhage, particularly in remote and austere surgical settings. Following a successful jHub opportunity assessment, DefER purchased training and operational kit at pace. By 1 April 2019, the first forward surgical group undertook a bespoke endovascular training and assessment package. Results of the pilot were presented back to a jHub 4* Innovation Board, which initially awarded £500 000 to fund the project to full implementation. Med Op Cap provided a solution to establish REBOA as a core capability on to the 370 modules. REBOA catheters and arterial access kit are now available to deployed Role 2 facilities across defence as an adjunct to damage control resuscitation in specific circumstances. REBOA has, from a standing start, gained pan-Defence Medical Services (DMS) endorsement and has been integrated into deployed damage control resuscitation. To establish a new resuscitation capability across all Role 2 platforms within 15 months of inception represents implementation at pace. This agility was unlocked by empowering clinicians to develop the platform in conjunction with commercial procurement. This article describes how this innovative pathway facilitated the rapid introduction of a lifesaving haemorrhage control technique to equip DMS clinicians.

Canonical relations between anthropometric and motor dimensions among 12-year-old students

The aim of this empirical research was to examine the correlations between the groups of variables of anthropometric characteristics (16) and motor skills (21) among 154 students (AM = 11,53 SD = 1,12). The method of canonical correlation analysis was used to assess the correlation between the pairs of linear functions of predictor and criterion variables. The obtained canonical coefficients and canonical weights revealed that, with significance level (p ≤ 0,0,5 or p ≤ 0,01), there is a high level of correlation between linear combinations of the examined morphological characteristics and motor skills, where the explained mutual variance was 80% for the first and 33% for the second canonical function. The extracted relevant canonical pairs were interpreted hypothetically as "integrated morphological factor and the factor of static and repetitive strength and coordination", and the second one was interpreted as "morphological factor and the factor of explosive strength". The set of the first canonical morphological factor and the factor of static and repetitive strength, and coordination, is the maximum weight on the variables body mass, body height, forearm circumference, horizontal reverse plank, knee push-ups, and stick mobility, while the biggest contribution to the structure of the second canonical morphological factor and the factor of static and repetitive strength have variables 20m sprint with standing start, standing long jump, hand tapping and foot tapping. The obtained results of the analyzed bicomponent canonical model reveal more defined and predictable structure of the correlation between anthropometric characteristics and motor manifestations, and therefore give guidelines for planning, developing and controlling the training processes during physical education classes.

Acute Effects of a Speed Training Program on Sprinting Step Kinematics and Performance

The purpose of this study was to examine the effects of speed training on sprint step kinematics and performance in male sprinters. Two groups of seven elite (best 100-m time: 10.37 ± 0.04 s) and seven sub-elite (best 100-m time: 10.71 ± 0.15 s) sprinters were recruited. Sprint performance was assessed in the 20 m (flying start), 40 m (standing start), and 60 m (starting block start). Step kinematics were extracted from the first nine running steps of the 20-m sprint using the Opto-Jump–Microgate system. Explosive power was quantified by performing the CMJ, standing long jump, standing triple jump, and standing five jumps. Significant post-test improvements (p < 0.05) were observed in both groups of sprinters. Performance improved by 0.11 s (elite) and 0.06 s (sub-elite) in the 20-m flying start and by 0.06 s (elite) and 0.08 s (sub-elite) in the 60-m start block start. Strong post-test correlations were observed between 60-m block start performance and standing five jumps (SFJ) in the elite group and between 20-m flying start and 40-m standing start performance and standing long jump (SLJ) and standing triple jump (STJ) in the sub-elite group. Speed training (ST) shows potential in the reduction of step variability and as an effective short-term intervention program in the improvement of sprint performance.