Do you even exercise, ref? Exploring habits of Spanish basketball referees during practice and matches.

Background: Basketball referees are a vital part of the organised competition system, although they remain an "outgroup" in sport. While physical development and fitness programming are deemed necessary for basketball officiating excellence, there is a paucity of literature exploring strategies for physical fitness management in this population. Methods: This research was a nationwide cross-sectional, self-administered online survey conducted in 2021. A sample of 628 (531 males, 97 females) referees from 18 regional referee organisations in Spain provided individual responses to gather information on demographic details, level of participation in refereeing, physical fitness practices, and match-day exercise-based regimens. The data were described using summary statistics, and the associations of the assessed variables were subsequently calculated using contingency tables. Results: Our findings reveal that a large fraction of the Spanish basketball referee population focuses on aerobic (83%) and strength (73.6%) activities, while less attention is paid to speed (36.9%) and flexibility (23.2%), and agility, coordination, and balance tasks are somewhat overlooked. No significant differences were observed among the referee categories regarding weekly training days or session duration, with most training for 15-60 min per session. Elite referees were more likely to hire personal trainers and engage in strength and flexibility exercises. Sub-elite referees showed a higher tendency to perform stretching and joint mobility activities post-match, while regional referees did so less frequently. Approximately 30.7% of referees across all competitive levels engaged in re-warm-up (RW-U) activities, with stretching and joint mobility being the most prevalent. Conclusions: Spanish basketball referees participate in routine physical exercise and fitness practices, irrespective of their competition level. While warm-up activities are prevalent, some sub-elite and regional referees do not consistently perform them, and re-warm-up routines are not extensively embraced.

Joint movement patterns differ among male recreational runners with different running style.

The purpose of this study was to analyse the differences in joint kinematic patterns among runners with different spatiotemporal characteristics in the running cycle. Lower extremity kinematic data and spatiotemporal stride parameters were collected for ninety-two recreational runners during a treadmill run at a self-selected comfortable speed. A K-means clustering analysis was conducted on normalised stride cadence and Duty Factor to identify running style. Cluster 1 characterised by reduced stance times and low Duty Factor; Cluster 2, long stance times and low stride cadence; Cluster 3, high Duty Factor and stride cadence. Functional principal component analysis was used to identify patterns of variability between runners. Runners who used a combination of high cadence and Duty Factor showed differences in hip, knee and ankle sagittal kinematics compared to other runners. On the contrary, the joint kinematics was not altered when the Duty Factor was increased along with a decrease in the stride cadence. This study has demonstrated that the combination of several spatial-temporal parameters of the running cycle should be considered when analysing the movement pattern of the lower limb.

Changes in Muscle Deoxygenation During Squat Exercise After 6-Week Resistance Training With Different Percentages of Velocity Loss.

ABSTRACT: Costilla, M, Casals, C, Marín-Galindo, A, Sánchez-Sixto, A, Muñoz-López, A, Sañudo, B, Corral-Pérez, J, and Ponce-González, JG. Changes in muscle deoxygenation during squat exercise after 6-week resistance training with different percentages of velocity loss. J Strength Cond Res 37(8): 1573-1580, 2023-The present study compared, for the first time, the effects of 6 weeks of 20% (20VL) vs. 40% (40VL) velocity loss (VL) resistance training (RT) programs on muscle oxygen dynamics during the squat exercise. Twenty-three young men (21.4 ± 2.4 years) were randomly allocated into the 20VL group ( n = 8), 40VL group ( n = 7), or control group (CG; n = 8). The RT program consisted of 3 sets of Smith machine back squat exercise at 20VL or 40VL with a 3-minute rest between sets, twice per week for 6 weeks. Tissue oxygenation index (TOI) was measured using near-infrared spectroscopy in the vastus medialis and vastus lateralis during a squat test (8-repetition 1 m·s -1 load test), and the maximum (maxTOI) and minimum (minTOI) TOIs were measured during a 3-min recovery period. After the 6-week RT program, TOI increased significantly at the beginning of the test in both muscles (during the first 4 repetitions in the vastus lateralis and 5 repetitions in the vastus medialis) in the 20VL group ( p < 0.05), with nonsignificant changes in the 40VL group and CG. The maxTOI was significantly increased in the vastus medialis (+3.76%) and vastus lateralis (+3.97%) after the training only in the 20VL group ( p < 0.05). The minTOI in the vastus medialis reached during the test remained unchanged postintervention for both training groups, with the CG showing significantly higher values compared with the 20VL group (+14.1%; p < 0.05). In conclusion, depending on the VL reached during a squat RT program, different changes in muscle oxygen dynamics can be expected. Training at 20% of VL improves metabolic efficiency and the reoxygenation peak after the set.

Effects of Different Velocity Loss Thresholds on Passive Contractile Properties and Muscle Oxygenation in the Squat Exercise Using Free Weights.

ABSTRACT: Muñoz-López, A, Marín-Galindo, A, Corral-Pérez, J, Costilla, M, Sánchez-Sixto, A, Sañudo, B, Casals, C, and Ponce-González, JG. Effects of different velocity loss thresholds on passive contractile properties and muscle oxygenation in the squat exercise using free weights. J Strength Cond Res 36(11): 3056-3064, 2022-The current study assessed the impact between different velocity loss thresholds on changes in the muscle contractile properties and muscle oxygenation after a single resistance training (RT) session. Thirty physically active men participated in a crossover study performing 3 sets of the squat exercise at a lifted speed of ≈0.75 m·s -1 , with 2 different velocity loss thresholds: 20% (VL20) vs 40% (VL40) in a randomized order. Contractile properties of the knee extensor muscles were tested using tensiomyography. In addition, muscle oxygenation was continuously measured from baseline until the end of the exercise session. The vastus lateralis showed a significant moment by condition interaction in time delay ( p = 0.044), muscle displacement ( p = 0.001), and contraction velocity ( p = 0.007), with greater reductions in VL40. In both trainings, oxygenated hemoglobin and tissue oxygen index decreased, whereas deoxygenated hemoglobin increased (moment as the main effect, p < 0.05), but without a moment by condition interaction. VL40 showed a lower deoxygenation slope in set 1 (-0.468%·s -1 , p = 0.001) and set 3 (-0.474%·s -1 , p = 0.037) as well as higher losses in set 1 (-41.50%, p = 0.003), set 2 (-41.84%, p = 0.002), and set 3 (-62.51%, p < 0.001), compared with VL20. No differences were found in the recovery period between conditions. In conclusion, during the RT program design, coaches and athletes should consider that VL40 produces higher mechanical and neuromuscular impairments than VL20, which seems to be necessary for hypertrophy to occur; however, VL40 also produces a longer period of lower oxygen supply than VL20, which can induce fast-to-slow muscle fiber transition.

Effects of Plyometric Vs. Combined Plyometric Training on Vertical Jump Biomechanics in Female Basketball Players.

The purpose of this study was to assess and compare the effects of plyometric training and combined training programs on vertical jump kinematics and kinetics of female basketball players. Thirty-six female basketball players were included in the study and further divided into three groups: plyometric training, n = 11; combined training n =13; and a control group, n =12. Combined training comprised full squat exercise with low resistance (50-65% 1RM) and low volume (3-6 repetitions/set) combined with repeated jumps. Plyometric training included drop jumps and repeated jumps. Both training methods showed a moderate increase in jump performance, although combined training achieved substantially higher values than plyometric training alone. After plyometric training, the vertical velocity and displacement of the center of mass of the countermovement jump increased, while force variables decreased. Combined training increased power, vertical velocity and displacement of the center of mass, but force variables remained unchanged. Both training methods improved jump height, velocity and displacement of the center of mass. Combined training maintained force measures while plyometric training decreased them. These results indicate that combined training might provide better outcomes on jump performance than plyometric training alone. It also appears important to measure biomechanical variables to appropriately interpret the effects of different training methods.

Verbal instructions affect reactive strength index modified and time-series waveforms in basketball players.

This study aimed to determine the effects of different verbal instructions, intended to affect the countermovement jump (CMJ) execution time, on the reactive strength index modified (RSIMod) and the time-series waveforms. Thirteen male basketball players performed six CMJs on a force plate with two different verbal instructions: 'jump as high as possible' (CMJhigh) and 'jump as high and as fast as possible' (CMJfast). Force-, power-, velocity-, and displacement-series waveforms, RSIMod and jump height were compared between conditions using statistical parametric mapping procedures. CMJfast showed greater values in RSIMod (p = 0.002) despite no differences in jump height (p = 0.345). Unweighting force (between 18% and 33% of total time) was lower in the CMJfast compared to CMJhigh. Larger force (between 53% and 63% of total time), velocity (between 31% and 48% of total time) and power (between 43% and 56% of total time) were found in the CMJfast compared to CMJhigh. These findings suggest that commanding athletes to jump as high and fast as possible increases rapid force production. Additionally, the results highlight the relevance of the countermovement phase in jumping and show that RSIMod could increase without power output modifications during propulsion, despite previous studies having reported positive associations between RSIMod propulsion power.

The effect of running speed on joint coupling coordination and its variability in recreational runners.

The purpose of this study was to examine the effect of speed on coordination and its variability in running gait using vector coding analysis. Lower extremity kinematic data were collected for thirteen recreational runners while running at three different speeds in random order: preferred speed, 15% faster and 15% lower than preferred speed. A dynamical systems approach, using vector coding and circular statistics, were used to quantify coordination and its variability for selected hip-knee and knee-ankle joint couplings. The influence of running speed was calculated from the continuous data sets of the running cycle, allowing for the identification of time percentages where differences existed. Results indicate that increases in running speed produced moderate alterations in the frequency of movement patterns which were not enough to alter classification of coordination. No effects of speed on coordination variability were observed. This study has demonstrated that coordination and coordination variability is generally stable in the range of ±15% around of preferred speed in recreational runners.

Application of the principal component waveform analysis to identify improvements in vertical jump performance.

The purpose of this study was to determine the effects of training on the force-, velocity-, and displacement-time curves using principal component analysis (PCA) to examine the pre to post intervention changes. Thirty-four trained women basketball players were randomly divided into training and control groups. The training intervention consisted of full squats combined with repeated jumps. The effects of the intervention were analysed before and after the training period of 6 weeks by comparing the principal component scores. The magnitude of differences within-/between-group were calculated and expressed as standardised differences. After the intervention period, clear changes in principal components were observed in the training group compared to the control group. These were related to the execution of a vertical jump with a faster and deeper countermovement that was stopped with greater force. This resulted in greater force from the start of the upward movement phase which was maintained for a longer time. This increase in force throughout a greater range of motion increased the take-off velocity and consequently jumping height.

Larger Countermovement Increases the Jump Height of Countermovement Jump.

Simulation studies show that jump performance can be improved by increasing the depth of countermovement. The purpose of this study was to determine how modifications to the depth of countermovement lead to changes in jump height and the biomechanical parameters related to center of mass displacement and force application. Twenty-nine competitive males participated in this investigation, performing nine countermovement jumps using a self-selected, a deep, and a shallow crouch position. Jump height and relative net vertical impulse were greater when using a deeper crouch position, compared to the self-selected position. Force application variables did not report differences, when the deeper countermovement was compared to the self-selected countermovement; although, the shallower countermovement showed higher values in force application parameters. The deeper countermovement jumps achieved higher velocities of the center of mass than the self-selected jumps, while shallower jumps produced lower velocities than the self-selected jumps. The results of this investigation were consistent with simulation studies, showing that deep countermovements increase net vertical impulse, leading to a higher jump height. In addition, the maximum downward velocity was higher, when the crouch position was deeper. Conversely, force-applied variables did not change when jump performance was increased.

Full Band Spectra Analysis of Gait Acceleration Signals for Peripheral Arterial Disease Patients.

Peripheral arterial disease (PAD) is an artherosclerotic occlusive disorder of distal arteries, which can give rise to the intermittent claudication (IC) phenomenon, i.e., limb pain and necessity to stop. PAD patients with IC have altered their gait, increasing the fall risk. Several gait analysis works have studied acceleration signals (from sensors) to characterize the gait. One common technique is spectral analysis. However, this approach mainly uses dominant frequency (fd ) to characterize gait patterns, and in a narrow spectral band, disregarding the full spectra information. We propose to use a full band spectral analysis (up to 15 Hz) and the fundamental frequency (f0) in order to completely characterize gait for both control subjects and PAD patients. Acceleration gait signals were recorded using an acquisition equipment consisting of four wireless sensor nodes located at ankle and hip height on both sides. Subjects had to walk, free-fashion, up to 10 min. The analysis of the periodicity of the gait acceleration signals, showed that f0 is statistically higher (p < 0.05) in control subjects (0.9743 ± 0.0716) than in PAD patients (0.8748 ± 0.0438). Moreover, the spectral envelope showed that, in controls, the power spectral density distribution is higher than in PAD patients, and that the power concentration is hither around the fd . In conclusion, full spectra analysis allowed to better characterize gait in PAD patients than classical spectral analysis. It allowed to better discriminate PAD patients and control subjects, and it also showed promising results to assess severity of PAD.

Heart rate variability is lower in patients with intermittent claudication: a preliminary study / La variabilidad de la frecuencia cardiaca es menor en pacientes con claudicación intermitente: un estudio preliminar

Introduction: Peripheral arterial disease is a chronic disorder affecting blood flow to lower limbs and many patients can develop intermittent claudication (IC). They suffer a blood flow decrease to lower limbs, making impossible to walk short distances without feeling pain or stopping the gait. Heart Rate Variability (HRV) is a non-invasive tool based on the calculation of time variations along consecutive heartbeats. It is reasonable to think that, since HRV assess the autonomic balance through the cardiovascular system, it could be useful in the assessment of patients with IC. Objectives: The aim of this study was to assess if there are differences in resting HRV between patients with IC and age matched controls, both with linear and non-linear analysis, and its possible relation with the gait capacity. Methods: 14 control male subjects (60±5 years) and 14 male IC patients (64±6 years) underwent 10 minutes of HRV analysis. The study calculated Time Domain variables, Poincaré Plot analysis and nonlinear parameters (Entropy and slopes of Detrend Fluctuation Analysis). Results: The main finding of this study is the presence of a clear sympathetic predominance at rest in the IC patients and a significant correlation between the parasympathetic rest tone and the distance covered in the 6MWT when all subjects are included. Conclusions: HRV seems to be an accurate method to detect the sympathetic misbalance present in patients with IC but as a nonspecific finding that could be present in other cardiovascular pathologies. Complex structure of the heartbeat signal is not affected by IC

Introducción: La enfermedad arterial periférica es un trastorno crónico que afecta al flujo sanguíneo de los miembros inferiores y muchos pacientes desarrollan claudicación intermitente (CI), sufriendo una reducción del flujo sanguíneo que les hace imposible caminar cortas distancias sin sufrir dolor o tener que detenerse. La variabilidad de la frecuencia cardiaca (VFC) es una herramienta no invasiva basada en el cálculo de las variaciones de tiempo entre latidos sucesivos. Es razonable pensar que, puesto que la VFC evalúa el balance autonómico a través del sistema cardiovascular, podría ser útil en la valoración de pacientes con CI. Objetivos: Evaluar si hay diferencias en la VFC de reposo entre pacientes con CI y controles de la misma edad (tanto con análisis lineal como no lineal) y su posible relación con la capacidad de marcha. Métodos: Se realiza un análisis de VFC de 10 min a 14 controles (60±5 años) y 14 pacientes con CI (64±6 años). Se calcularon variables del dominio de tiempo, gráfico de Poincaré y parámetros no lineales. Todos los sujetos realizaron a continuación un test de 6 min. Resultados: El principal hallazgo de este estudio es la presencia de un claro predominio simpático en reposo en los pacientes con CI y una correlación significativa entre el tono parasimpático de reposo y la distancia recorrida en el test de 6 min. Conclusiones: La VFC parece ser un método adecuado para detectar la disfunción simpática presente en pacientes con CI pero como un hallazgo inespecífico que puede estar presente en otras patologías vasculares. La estructura compleja de la señal cardiaca no se ve afectada en la CI

Effects of running experience on coordination and its variability in runners.

The purpose of this study was to examine the differences in coordination variability in running gait between trained runners and non-runners using continuous relative phase (CRP) analysis. Lower extremity kinematic data were collected for 22 participants during the stance phase. The participants were assigned to either a runner or non-runner group based on running volume training. Segment coordination and coordination variability were calculated for selected hip-knee and knee-ankle couplings. Independent t-tests and magnitude-based inferences were used to compare the 2 groups. There were limited differences in the CRP and its variability among runners and non-runner groups. The runners group achieved moderately lower coordination compared with non-runners group in the phase angle for hip abduction/adduction and knee flexion/extension. The runners tended to show moderately lower coordination variability in the phase angle for knee flexion/extension and subtalar inversion/eversion in comparison to non-runners group. These results suggested that levels of experience as estimated from weekly training volume had little influence on coordination and its variability.