Relationship between Muscle-Tendon Stiffness and Drop Jump Performance in Young Male Basketball Players during Developmental Stages

Background: The relationship between stiffness and drop jump performance in athletes in various stages of development has yet to be fully investigated. The first aim of this study was to investigate the association between the stiffness of the patellar and quadriceps tendon (PT, QT), gastrocnemius–Achilles tendon unit (GAT), and rectus femoris (RF) using drop jump (DJ) performance in young basketball players. The second aim was to investigate possible variations in the stiffness levels of those tissues in different developmental stages. Methods: The stiffness levels of the GAT, PT, QT, and RF were measured in both limbs in 73 male basketball players aged 12 to 18 years. The reactive strength index (RSI), contact time (CT) and jump height (JH) during 30 and 40 cm DJs were also measured. Results: Pearson correlation coefficients showed a significant association between DJ performance and PT, QT, GAT, and RF dynamic stiffness. Moreover, the youngest subjects were found to have lower stiffness values than the older ones. Conclusions: Tissue stiffness can affect athletic performance by modifying the stretch-shortening cycle in young basketball players. Stiffness of muscles and tendons increases during the maturation process. Further investigations could shed light on the effect of training on the stiffness of muscles and tendons

Effects of fatigue on muscle stiffness and intermittent sprinting during cycling

Purpose: It was recently demonstrated that musculoarticular (MA) stiffness is related to sprint cycling performance in nonfatigued conditions. This study examined whether relatively stiffer cyclists were more effective at sprinting under fatigued conditions, as occurs during endurance cycling competitions. Methods: MA stiffness of the quadriceps was assessed in 21 trained male cyclists (28.7 ± 9.5 yr, 1.74 ± 0.08 m, 67.5 ± 7.2 kg). Participants also performed a maximal 6-s sprint on a cycle ergometer to assess peak power output (PO peak ), peak crank torque (CT peak ), and peak rate of crank torque development (RCTD peak ). A cycling fatigue protocol then required cyclists to pedal at 30%, 35%, and 40% of PO peak and sprint at the end of each stage. Surface EMG was recorded from vastus lateralis during each sprint and analyzed in the time domain as integrated EMG (iEMG) and in the frequency domain as instantaneous median frequency (MDF) adopting a continuous wavelet transform. Participants were then retested for MA stiffness. Results: MA stiffness (-12%) was significantly reduced after the cycling protocol. Further, PO peak , CT peak , RCTD peak , and iEMG were reduced by 20%, 15%, 13%, and 20%, respectively, after the fatigue protocol (P < 0.05). When the cyclists were divided into relatively stiff (SG) and relatively compliant groups (CG), only SG exhibited significant decreases in MA stiffness, C T peak , RCTD peak (P < 0.05), and instantaneous MDF (R = 0.705). Conclusions: Whereas neuromechanical parameters were generally reduced under conditions of fatigue, stiff and compliant cyclists were affected differently, with the sprint abilities of SG decreased to the level of CG. It seems important for endurance cyclists to incorporate training strategies to maintain MA stiffness during competition to offset declines in sprint performance. © 2011 by the American College of Sports Medicine

Regional Hypertrophy: The Effect of Exercises at Long and Short Muscle Lengths in Recreationally Trained Women

The aim of the present study was to analyse the role of exercises' resistance profile in regional hypertrophy. Thirty-eight healthy women completed a 9-week resistance training program consisting of either 4 sets of 12 repetitions to volitional failure of inclined bicep curls (INC group) or preacher curls (PREA group), three times per week. Pre- and post-intervention muscle thickness was measured using B-mode ultrasound imaging with a linear-array transducer. Scan acquisition sites were determined by measuring 50%, 60% and 70% of the distance between the posterior crest of the acromion and the olecranon. Statistical significance was set at p < 0.05. No region of the INC group grew when comparing pre- to post-intervention. The 70% region of the PREA group grew significantly (muscle thickness increased from 2.7 ± 0.43 cm to 2.94 ± 0.44 cm). We found no growth differences between regions when analysing per group (p = 0.274), region (p = 0.571) or group*region (p = 0.367). Our results show that the distal region of the arm grows in response to the preacher curl that places the highest amount of strain in the range of motion in which the arm muscles are more elongated

Efectos del sistema de pedaleo no circular q-ring sobre el rendimiento en el sprint de la disciplina ciclista BMX

The aim of this study was to evaluate the possible benefits of using a non-circular chain-wheel system QRing (Q) versus a conventional one (NQ) on the performance in the Bicycle Moto Cross (BMX) sprint cycling discipline. Fourteen riders belonging to the Spanish National Team performed a sprint test (3.95 s of duration, randomized and counterbalanced), from the starting gate ramp in a BMX track. The T-Test contrast analysis for related samples showed no statistically significant differences for the variables Average Speed (Vmean) and Time in 31m (T31m) between Q and NQ, when considering the group as a whole. However, when the analysis considered two groups separately: Experts vs Novice, we found significant differences for Q vs NQ within the Experts (Vmean: 5.91±0.03 vs.5.81±0.05 m/s; T31m: 3.21±0.02 vs 3.23 ± 0.02 s; P <0.05); what meant an improvement up to 40 cm in the distance covered within this first 3.95 seconds. Hence, our results suggest that the non-circular chain-wheel system Q-Ring improves sprint performance in BMX, provided the riders have a conditional level enough to ensure the capacity to develop the pedaling properly, despite of the strength needed.El objetivo de este estudio ha sido evaluar los efectos de un sistema de plato no circular de desarrollo variable Q-Ring (Q) frente a uno convencional (NQ) sobre el rendimiento en el sprint ciclista de Bicicleta de Moto Cross (BMX). Catorce deportistas pertenecientes a la Selección Nacional Española han realizado un test de sprint, desde la rampa de salida, en una pista de BMX (3.95 s de duración; orden randomizado y contrabalanceado). El análisis de contraste prueba T para muestras relacionadas no muestra diferencias estadísticamente significativas para las variables Velocidad media (Vmedia) y Tiempo en 31m (T31m) entre Q y NQ cuando considera al grupo en su conjunto. Sin embargo, al dividir la muestra entre deportistas Expertos y Noveles, encontramos diferencias a favor de Q respecto de NQ entre los Expertos (Vmedia: 5.91±0.03 vs 5.81±0.05 m/s; T31m: 3.21±0.02 vs 3.23±0.02 s; P < 0.05), diferencias que se traducen hasta en 40 cm de ganancia en los 3.95 primeros segundos de carrera. Estos resultados sugieren que el sistema Q mejora el rendimiento en el sprint de la especialidad ciclista BMX siempre que el deportista posea la capacidad de mover adecuadamente su desarrollo

A directional ellipse to describe directional behavior and player activity area in soccer

This study aimed to compare four standard deviational ellipse models to assess directional behavior and player activity area in four small-sided games (SSG) of soccer played on pitches with the same width (40 m) and different lengths (30, 40, 50, and 60 m). Fourteen participants played four 7-a-side SSGs on each of the four pitch sizes. Based on GPS data, four ellipse models were calculated for each outfield player and pitch size: major ranges (MR) measuring standard deviation in fixed length and width directions, linear regression assuming length (LRLvsW) or width (LRWvsL) as the independent variable, and principal component analysis (PCA) assuming both length and width as independent variables. Slope, area, semi-major and semi-minor axes, and eccentricity were calculated for each ellipse model. The PCA and LRLvsW models showed similar and valid results for each variable, especially for larger pitch sizes. LRWvsL showed unreliable results. The length axis should be considered as the independent axis when assessing the main direction of players’ movements and playing area through a standard deviational ellipse in soccer. This methodology could also be applied to evaluate a team’s labor distribution and spatial distribution of its players

Moderate intensity active recovery improves performance in a second wingate test in cyclists

Background: The aim of the present study was to compare the effects of active (AR) vs. passive recovery (PR) between two Wingate Anaerobic Tests (WAnT) on power output, blood lactate (BLa) and oxygen consumption (VO2) in a second WAnT. Methods: Twelve well-trained cyclists underwent three experimental sessions. In the first session, they completed an incremental test for maximum oxygen consumption (V O2max) and lactate threshold determination. In the second and third sessions, cyclists completed, in random order, two WAnT tests separated by 30-min recovery intervals, during which they performed an AR at 70% of the V O2 at lactate threshold (V O2LT) or a PR. The cardiorespiratory, metabolic, and mechanical responses in the two recovery conditions were compared. Results: No differences were found in the VO2-on kinetics between WAnT tests (p > 0.05). As expected, blood lactate kinetics showed a greater clearance (from the 7th to the 31st min, p  0.05). Mean and peak power, and total work were significantly higher in the second WAnT after AR (p < 0.001), while the power decline was also lower in this condition (p < 0.05). Conclusion: The submaximal active recovery strategy used in the present study can induce an improvement in mechanical power and total work during a second WAnT. This suggests that AR of submaximal intensity can induce a post-activation performance enhancement when used during the recovery phase between maximal anaerobic efforts

The effect of topical thiocolchicoside in preventing and reducing the increase of muscle tone, stiffness, and soreness: A real-life study on top-level road cyclists during stage competition

In professional road cyclists, the majority of overuse injuries affect the lower limbs and are mostly represented by contractures or muscle shortening, characterized by an increase of tone and stiffness and a variation of elasticity. Treatment and prevention of these specific conditions may include physical, supplementary, and pharmacologic support. The aim of this real-life study was to determine: first, the alterations of tone, stiffness, elasticity, and soreness of rectus femoris (RF) and biceps femoris (BF) in top class cyclists engaged in 3 multistage races, and second, whether any variable in the management of the athletes may affect the prevention and/or reduction of such alterations.Twenty-three professional cyclists competing in 3 international, cycling stage races were assessed. Athletes could receive, upon the approval of the medical staff, physical, dietary, and/or pharmacological management which could include treatments with topical over-the-counter myorelaxants to prevent and/or reduce muscle contractures. MyotonPro was used to daily measure tone, stiffness, and elasticity in RF and BF in relaxed and contracted state after every stage. In parallel, BF and RF soreness was also assessed with a Likert scale.All athletes received the same general massage management; none of them received dietary supplements; some of the athletes were treated with a topical myorelaxant thiocolchicoside (TCC 0.25%) foam 3 times daily. TCC was identified as the only variable able to affect these muscle parameters in the cyclists. Tone, stiffness (regardless of the state), and soreness significantly increased over time either in BF or RF in all athletes. In the group of athletes that used TCC (n = 11; TCC+) the increase in tone, stiffness, and soreness was significantly lower than in the group not receiving TCC (n = 12; No-TCC). Elasticity varied coherently with tone and stiffness.A very intense and protracted sport activity increases muscular tone, stiffness, and soreness over time. Topical TCC foam significantly attenuates these alterations and might represent an efficient strategy both to prevent and manage contractures and their consequences in professional cyclists as well in athletes from other disciplines involving similar workloads

On the origin of rural landscapes: Looking for physico-chemical fingerprints of historical agricultural practice in the Atlantic Basque Country (N Spain)

Evolution and change in agricultural practice is a major factor in the codification of social relations and represents one of the main resources employed by human societies to establish a durable relationship with their environment. Using a multi-proxy integrated approach, this paper seeks to decipher the long-term dynamics that have shaped agricultural landscapes in the Basque Country (N Spain). Social and economic indicators (archival records, toponymy and oral sources) are used along with geological core sampling (geochemistry, magnetic, palynological and carpological analyses) to reconstruct a diachronic sequence of human settlement and agricultural management in the village of Aizarna over the last ~1500 years. The oldest records obtained refer to non-agricultural human activities dating back to the Roman period. Later on, traces of agricultural landscape-transformation can be divided into four main phases: 1) the onset of terraced agriculture, defined by the clearance and terracing of previous forested areas during the Early Middle Ages; 2) a Late Medieval reorganisation, with new terraces being (re)constructed close to dispersed farmsteads, linked to the emergence of the modern rural landscape; 3) a new model of intensive polyculture developed during the Modern period as a consequence of the introduction of new crops of American origin; and 4) the mechanisation and commercialisation of the agricultural production over the 20th century. These results provide a valuable pathway for the investigation of currently inhabited rural contexts, and offer, for the first time in this region, an overview on long-term landscape construction in the Atlantic areas of the Basque Country.Fieldwork was funded by the Culture Department of the Provincial Government of Gipuzkoa, and by the Project “Peasant Agency and socio-political complexity in the northwest of the Iberian Peninsula during the Middle Ages” (Ministry of Economy, AEI/FEDER EU HUM2016-76094-C4-2-R), jointly participated in by the Research Group on Heritage and Cultural Landscapes (Basque Government, IT936-16) and the Group of Rural Studies (UPV/EHU-CSIC Associated Unit). Á. Carrancho acknowledges the financial support given by the Consejería de Educación, Junta de Castilla y León (project BU235P18) with also FEDER funding