Placebo Effect of Caffeine on Physiological Parameters and Physical Performance.

This study aimed to analyse the placebo effect associated with a high dose of caffeine (9 mg/kg) on heart rate and its variability and on strength tests. METHODS: 18 participants experienced in strength training (19.7 ± 2.3 years; 72.2 ± 15.0 kg; 169.6 ± 9.0 cm) performed two days of trials (caffeine-informed/placebo-ingested (placebo) and non-ingested (control)). Firstly, heart rate and its variability were measured while participants lay down for 15 min. After that, bench press and squat tests were performed at 3 different loads (50%, 75% and 90% of 1RM). Perception of performance, effort and side effects were also evaluated. RESULTS: no differences were found in the vast majority of strength variables analysed. Resting heart rate decreased in the placebo trial (60.39 ± 10.18 bpm control vs. 57.56 ± 9.50 bpm placebo, p = 0.040), and mean RR increased (1020.1 ± 172.9 ms control vs. 1071.5 ± 185.7 ms placebo, p = 0.032). Heart rate variability and perception of performance and effort were similar between conditions (p > 0.05 in all cases). Side effects such as activeness and nervousness were reported while consuming the placebo. CONCLUSIONS: the placebo effect did not modify performance in the majority of the strength test variables, HRV and perception of performance and effort. However, resting heart rate was reduced, mean RR increased, and some side effects appeared in the placebo trial.

A Five-Week Periodized Carbohydrate Diet Does Not Improve Maximal Lactate Steady-State Exercise Capacity and Substrate Oxidation in Well-Trained Cyclists compared to a High-Carbohydrate Diet.

There is a growing interest in studies involving carbohydrate (CHO) manipulation and subsequent adaptations to endurance training. This study aimed to analyze whether a periodized carbohydrate feeding strategy based on a daily training session has any advantages compared to a high-carbohydrate diet in well-trained cyclists. Seventeen trained cyclists (VO2peak = 70.8 ± 6.5 mL·kg-1·min-1) were divided into two groups, a periodized (PCHO) group and a high-carbohydrate (HCHO) group. Both groups performed the same training sessions for five weeks. In the PCHO group, 13 training sessions were performed with low carbohydrate availability. In the HCHO group, all sessions were completed following previous carbohydrate intake to ensure high pre-exercise glycogen levels. In both groups, there was an increase in the maximal lactate steady state (MLSS) (PCHO: 244.1 ± 29.9 W to 253.2 ± 28.4 W; p = 0.008; HCHO: 235.8 ± 21.4 W to 246.9 ± 16.7 W; p = 0.012) but not in the time to exhaustion at MLSS intensity. Both groups increased the percentage of muscle mass (PCHO: p = 0.021; HCHO: p = 0.042) and decreased the percent body fat (PCHO: p = 0.021; HCHO: p = 0.012). We found no differences in carbohydrate or lipid oxidation, heart rate, and post-exercise lactate concentration. Periodizing the CHO intake in well-trained cyclists during a 5-week intervention did not elicit superior results to an energy intake-matched high-carbohydrate diet in any of the measured outcomes.

A Retrospective Analysis of High Resolution Ultrasound Evaluation of the "Split Fat Sign" in Peripheral Nerve Sheath Tumors.

Peripheral nerve sheath tumors (PNST) comprise schwannomas and neurofibromas. The finding of increased adipose tissue around benign PNSTs has been described as the "split fat sign" on magnetic resonance imaging exams, which is suggestive of an intramuscular or intermuscular location of the tumor. However, few studies have described this sign as a salient ultrasound feature of PNSTs. The main purpose of this study was to retrospectively evaluate the presence of increased fatty tissue deposition around benign PNSTs diagnosed by high-resolution ultrasound. In addition, we aimed to corroborate the presence of vascularization around the affected area. A retrospective analysis of ten cases of PNSTs and two cases of post-traumatic neuromas diagnosed by high-resolution ultrasound was performed with a Logiq® P8 ultrasound with a 2-11 MHz multifrequency linear probe L3-12-D (central frequency: 10 MHz). Localized types of neurofibromas and schwannomas in any location were seen as predominantly hypoechoic tumors with an oval or fusiform shape. Exiting and entering nerves (tail sign) were observed in six cases, showing localized lesions both in intermuscular and subcutaneous locations. The presence of increased hyperechoic tissue (the split fat sign) was noted in cases of solitary intermuscular and intramuscular peripheral nerve sheath tumors, mainly the schwannomas. Though small tumors did not demonstrate the tail sign, the increase in adipose tissue and vascularity on US was well demonstrated. In conclusion, the nerve in continuity forms the basis of the ultrasonographic diagnosis of PNSTs. However, high-resolution US can convincingly demonstrate the increased presence of fat in the upper and lower poles as well as circumferentially in intermuscular or intramuscular benign PNSTs.

Influencia del ciclo menstrual en el rendimiento físico y cognitivo en mujeres eumenorreicas / Influence of the menstrual cycle on physical and cognitive performance in eumenorrheic women

Introducción: Las hormonas sexuales femeninas propias del ciclo menstrual no solo tienen funciones reproductivas, tambiéninfluyen en otros sistemas fisiológicos pudiendo afectar al rendimiento deportivo y cognitivo. El propósito del presente estudioha sido evaluar distintos aspectos como la composición corporal, la resistencia, la fuerza muscular y algunas capacidadescognitivas en diferentes etapas del ciclo menstrual. Material y método: En el estudio participaron ocho mujeres jóvenes eumenorreicas (edad = 23,1 ± 4,4 años) con ciclosmenstruales regulares. Se realizó una prueba de densitometría y una bioimpedancia para estudiar la composición corporal, unaprueba de memoria visual a corto plazo y un test de tiempo de reacción para evaluar habilidades cognitivas y se analizaroncaracterísticas del músculo (grosor y rigidez del recto anterior y fuerza muscular) junto a una prueba de esfuerzo para evaluarel rendimiento durante las fases folicular media (FF) y lútea media (FL) del ciclo menstrual de las participantes. Resultados: Durante la fase folicular las participantes registraron un mayor tiempo total (FF = 488,5 ± 93,18 s vs. FL = 468,6± 81,29 s; p = 0,015) y una frecuencia cardiaca inicial menor (FF = 83,3 ± 10,23 PPM vs. FL = 92,9 ± 7,67 PPM; p = 0,034) en laprueba de esfuerzo. Además, Respecto a las habilidades cognitivas, en la fase folicular se obtuvieron mejores resultados enel tiempo de reacción tanto con la mano derecha (FF = 0,426 ± 0,082 s vs. FL = 0,453 ± 0,087 s; p = 0,036) como con la manoizquierda (FF = 0,435 ± 0,096 s vs. FL = 0,466 ± 0,077 s; p = 0,034). Por otro lado, se encontró un mayor porcentaje de grasa(FF = 27,3 ± 5,1% vs. FL = 27,9 ± 5,0%; p = 0,041) en la fase lútea. Conclusión: El rendimiento en resistencia y en aspectos cognitivos como es el tiempo de reacción fue mejor en la FaseFolicular mientras que se observó un mayor porcentaje de grasa en la Fase Lútea. Sin embargo, la memoria, la fuerza y lascaracterísticas...(AU)

Introduction: The female sexual hormones typical of the menstrual cycle not only have reproductive functions, they alsoinfluence other physiological systems and can affect sports and cognitive performance. The purpose of this study has beento evaluate different aspects such as body composition, endurance, muscle strength and some cognitive abilities at differentstages of the menstrual cycle. Material and method: Eight young eumenorrheic women (age = 23.1 ± 4.4 years) with regular menstrual cycles participatedin the study. A densitometry and bioimpedance test were performed to study body composition, a short-term visual memorytest and a reaction time test to assess cognitive abilities, and muscle characteristics (thickness and stiffness of the anteriorrectus and muscle strength) along with a progressive test to exhaustion were analyzed to assess performance during themid-follicular (FF) and mid-luteal (FL) phases of the participants’ menstrual cycle. Results: During the follicular phase, the participants registered a greater total time (FF = 488.5 ± 93.18 s vs. FL = 468.6 ± 81.29 s;P = 0.015) and a lower initial heart rate (FF = 83.3 ± 10.23 PPM vs. FL = 92.9 ± 7.67 PPM; P = 0.034) in the progressive test toexhaustion. Regarding cognitive abilities, in the follicular phase, better results were obtained in reaction time both with theright hand (FF = 0.426 ± 0.082 s vs. FL = 0.453 ± 0.087 s; P = 0.036) and with the left hand (FF = 0.435 ± 0.096 s vs. FL = 0.466 ±0.077 s; P = 0.034). On the other hand, a higher percentage of fat (FF = 27.3 ± 5.1% vs. FL = 27.9 ± 5.0%; P = 0.041) was foundin the luteal phase. Conclusion: Performance in endurance and in cognitive test, such as reaction time was better in the Follicular Phase, whilea higher percentage of fat was observed in the Luteal Phase. However, memory, strength and muscular characteristics werenot affected by the hormonal fluctuations of the menstrual cycle.(AU)

Five-Compressions Protocol as a Valid Myotonometric Method to Assess the Stiffness of the Lower Limbs: A Brief Report.

The objective of this study was to evaluate the validity of a short assessment MyotonPRO protocol to measure the stiffness of the superficial muscles and tendons of the lower limbs. The stiffness of the dominant lower limb vastus lateralis (VL), rectus femoris (RF) and patellar tendon (PT) was evaluated in 52 healthy participants (26.9 ± 3.4 years) with two MyotonPRO protocols: the standard protocol (10 mechanical taps) and the short protocol (five mechanical taps). The myotonometry was performed at the midpoint of the length from the upper pole of the patella to the greater trochanter for the VL, and to the anterior superior iliac spine for the RF. The PT was evaluated 1 cm caudal from the inferior pole of the patella. Pearson's correlation coefficients were calculated to determine the relationships between protocols. The validity of the short protocol was evaluated with Student's t-test. High positive correlations were observed between the short and standard protocols in the stiffness of the VL (r = 0.959; p < 0.001), the RF (r = 0.967; p < 0.001) and the PT (r = 0.953; p < 0.001) and no differences were found between both protocols in the stiffness assessment of the VL, RF and PT (p > 0.05). Therefore, the five-compressions protocol is a valid protocol for the assessment of lower limb mechanical properties.

The Applicability of Shear Wave Elastography to Assess Myotendinous Stiffness of Lower Limbs during an Incremental Isometric Strength Test.

The aim of the study was to describe the applicability of shear wave elastography to assess muscular and tendinous stiffness of the lower limbs during an incremental isometric strength test and to differentiate the stiffness evolution between superficial and deep muscle regions. Dominant rectus femoris and patellar tendons of 30 physically active people (28.3 ± 9.2 years, 173.2 ± 7.7 cm, 76.2 ± 12.6 kg) were measured in different isometric strength conditions (relaxed muscle, and at 10%, 20%, 30%, 40%, 50% and 60% of maximal voluntary contraction (MVC)). The percentage of success was >85% at all muscle contraction intensities for rectus femoris muscles but only in a relaxed condition for patellar tendons. Rectus femoris stiffness significantly increased compared to the relaxed condition from 30% to 60% MVC (p ≤ 0.011) in superficial muscle regions, and from 10% to 60% MVC (p ≤ 0.002) in deep muscle regions. Deep muscle regions showed higher stiffness values than superficial muscle regions at 30% MVC (51.46 ± 38.17 vs. 31.83 ± 17.05 kPa; p = 0.019), 40% MVC (75.21 ± 42.27 vs. 51.25 ± 28.90 kPa; p = 0.018), 50% MCV (85.34 ± 45.05 vs. 61.16 ± 37.03 kPa; p = 0.034) and 60% MVC (109.29 ± 40.04 vs. 76.67 ± 36.07 kPa; p = 0.002). Rectus femoris stiffness increased during the incremental isometric contraction test, and inter-region differences were found at 30% MVC.

The Effects of Eccentric Contraction Execution Time on the Properties of the Patellar Tendon.

The purpose of this study was to assess the effects of eccentric contraction execution time on the morphological and elastic properties of the patellar tendon (PT) in a six-week, single-leg decline squat (SLDS) exercise training program. In addition, the effects of a six-week detraining period on the same variables were evaluated. Fifty participants were randomized into the control group (CG; n = 15), experimental group 1 (EG6s; n = 17; eccentric contraction execution time = 6 s) and experimental group 2 (EG3s; n = 18; eccentric contraction execution time = 3 s). The thickness and elastographic index (EI) in different regions of interest (ROIs) in the PT were measured after 6 weeks of eccentric training using the single-leg decline squat exercise (three sessions per week, 80% of the eccentric one-repetition maximum) and after 6 weeks of detraining. There was an increase in the thickness of the PT in the different ROIs analyzed in both experimental groups at the end of the training period. Especially worth noting was the increase in the thickness of the PT at the proximal level in EG3s (p = 0.001), and the increase at the distal level in EG6s (p = 0.001). On the other hand, there was a reduction in EI in EG6S at the end of the intervention program (p = 0.021), and both experimental groups increased EI in the three regions of interest analyzed after the detraining period (p < 0.01). In conclusion, the execution time of the eccentric contraction in the SLDS exercise determines the anatomical level of the morphological adaptations in the PT. These morphological adaptations are lost after 6 weeks of detraining, producing an increase in tendon stiffness.

Influence of Secondary School Students' Physical Fitness on Sports Performance during an Ultimate Frisbee Competition.

The aim of the present study was to investigate the effect of secondary school students' fitness profile on physical and technical−tactical performance in simulated competition conditions of ultimate frisbee when there is no previous experience in the practice of the sport. Forty-three secondary school students participated in this research. The students were divided into two groups according to their results in the Assessing Levels of Physical Activity and fitness test battery (ALPHA fitness test): poor physical fitness (PPF) (N = 24; age: 14.9 ± 0.8 years; height: 166.1 ± 10.9 cm; body mass: 62.2 ± 11.0 kg; ALPHA fitness score: 2.7 ± 0.7 points) and good physical fitness (GPF) (N = 19; age: 14.5 ± 0.6 years; height: 165.9 ± 5.8 cm; body mass: 58.9 ± 7.5 kg; ALPHA fitness score: 4.4 ± 0.3 points). Physical variables during the ultimate frisbee match were assessed using Global Positioning System technology. The matches were video-recorded, and individual technical actions were noted afterwards. The GPF group showed higher values for running (p = 0.039), high-speed running (p = 0.015), sprinting (p = 0.022) and total distance covered (p = 0.025) than the PPF group. In addition, more passes (p = 0.019), offensive decision making (p = 0.009) and player participation (p = 0.046) were recorded in the GPF group than the PPF group. Correlational analysis revealed a positive relationship (p < 0.05) between individual participation and the meters covered for jogging, running, running at high speed and sprinting during the game. In conclusion, although the students were novices in ultimate frisbee, the high physical fitness level had a positive effect on the game performance. Physical education teachers should consider this information when introducing new sports into their physical education classes.

Effects of Plyometric Training on Lower Body Muscle Architecture, Tendon Structure, Stiffness and Physical Performance: A Systematic Review and Meta-analysis.

BACKGROUND: Plyometric training (PT) has been widely studied in sport science. However, there is no review that determines the impact of PT on the structural variables and mechanical properties of the lower limbs and physical performance. OBJECTIVE: The aim of this systematic review and meta-analysis was to determine the effects of PT on lower body muscle architecture, tendon structure, stiffness and physical performance. METHODS: Five electronic databases were analysed. The inclusion criteria were: (1) Availability in English; (2) Experimental studies that included a PT of at least eight sessions; and (3) Healthy adults subjects. Four meta-analyses were performed using Review Manager software: (1) muscle architecture; (2) tendon structure; (3) muscle and tendon stiffness; (4) physical performance. RESULTS: From 1008 search records, 32 studies were eligible for meta-analysis. Muscle architecture meta-analysis found a moderate effect of PT on muscle thickness (Standard Mean Difference (SMD): 0.59; [95% Confidence Interval (CI) 0.47, 0.71]) and fascicle length (SMD: 0.51; [95% CI 0.26, 0.76]), and a small effect of PT on pennation angle (SMD: 0.29; [95% CI 0.02, 0.57]). The meta-analysis found a moderate effect of PT on tendon stiffness (SMD: 0.55; [95% CI 0.28, 0.82]). The lower body physical performance meta-analysis found a moderate effect of PT on jumping (SMD: 0.61; [95% CI 0.47, 0.74]) and strength (SMD: 0.57; [95% CI 0.42, 0.73]). CONCLUSION: PT increased the thickness, pennation angle and fascicle length of the evaluated muscles. In addition, plyometrics is an effective tool for increasing tendon stiffness and improving jump and strength performance of the lower body.

Effects of Eccentric Single-Leg Decline Squat Training Performed With Different Execution Times on Maximal Strength and Muscle Contraction Properties of the Knee Extensor Muscles.

ABSTRACT: Abián-Vicén, J, Martínez, F, Jiménez, F, and Abián, P. Effects of eccentric single-leg decline squat training performed with different execution times on maximal strength and muscle contraction properties of the knee extensor muscles. J Strength Cond Res 36(11): 3040-3047, 2022-The eccentric phase of the single-leg decline squat (SLDS e ) has been described as a method to maximally load the knee extensor and has been used as an easy and effective rehabilitation exercise for patellar tendinopathy. The purpose of this study was to examine the impact of 6-week SLDS e training with 2 technical execution times on changes related to strength and muscle contractile properties. Thirty-six healthy volunteers were randomly divided into 3 groups: a control group (CG, n = 13, no training), a slow training group ( n = 11, SLDS e in 6 seconds), and a fast training group ( n = 12, SLDS e in 3 seconds). Subjects completed a 6-week SLDS e training program (80% of eccentric one repetation maximum [1RM]) 3 days a week. Pre, post, and 6-week follow-up of maximal dynamic and isometric strength and muscle contractile properties were assessed. After 6 weeks, training maximal loads showed a significant increase ( p < 0.05) in 1RM of the SLDS e (∼92-95%), the concentric peak torque at 180°·s -1 (∼38%) and 60°·s -1 (∼25%), and the extension isometric peak torque (∼12%), with no differences between both experimental groups. Moreover, a decrease ( p < 0.05) was found in the contraction time of the vastus medialis (VM) and the response time of the 3 analyzed quadriceps muscles. After the 6-week detraining period, there was a decrease in strength in all tests and in both experimental groups (1RM = 28-37%, isometric and isokinetic tests = 7-17%) and all contractile properties returned to baseline, except for the response time of the vastus lateralis in the fast training group and the contraction time of the VM in the STG. In conclusion, the SLDS e training protocol produced significant increases in muscle strength, showing important neuromuscular changes regardless of the technical execution time. It was also found that the training reduced the response and contraction time of the knee extensor musculature.

Genotype Distribution of the ACTN3 p.R577X Polymorphism in Elite Badminton Players: A Preliminary Study.

α-Actinin-3 is a protein with a structural role at the sarcomeric Z-line in skeletal muscle. As it is only present in fast-type muscle fibers, α-actinin-3 is considered a key mechanical component to produce high-intensity muscle contractions and to withstand external tension applied to the skeletal muscle. α-Actinin-3 is encoded by the gene ACTN3, which has a single-nucleotide polymorphism (p.R577X; rs1815739) that affects the expression of α-actinin-3 due to the presence of a stop codon. Individuals homozygous for the 577R allele (i.e., RR genotype) and RX heterozygotes express functional α-actinin-3, while those homozygous for the 577X (i.e., XX genotype) express a non-functional protein. There is ample evidence to support the associations between the ACTN3 genotype and athletic performance, with higher frequencies of the 577R allele in elite and professional sprint and power athletes than in control populations. This suggests a beneficial influence of possessing functional α-actinin-3 to become an elite athlete in power-based disciplines. However, no previous investigation has determined the frequency of the ACTN3 genotypes in elite badminton players, despite this sport being characterized by high-intensity actions of intermittent nature such as changes of direction, accelerations, jumps and smashes. The purpose of this study was to analyze ACTN3 R577X genotype frequencies in professional badminton players to establish whether this polymorphism is associated with elite athlete status. A total of 53 European Caucasian professional badminton players competing in the 2018 European Badminton Championships volunteered to participate in the study. Thirty-one were men (26.2 ± 4.4 years) and twenty-two were women (23.4 ± 4.5 years). Chi-squared tests were used to analyze the differences in the distribution of ACTN3 genotypes (RR, RX and XX) between categories and sexes. The ACTN3 RR genotype was the most frequent in the sample of professional badminton players (RR = 49.1%, RX = 22.6% and XX = 28.3%). None of the badminton players ranked in the world's top ten possessed the XX genotype (RX = 60%, RR = 40%). The distribution of the ACTN3 genotypes was similar between male and female professional badminton players (men: RR = 45.2%, RX = 25.8% and XX = 29.0%; women: RR = 54.5%, RX = 18.2% and XX = 27.3%; χ2 = 0.58; p = 0.750). The distribution of the ACTN3 genotypes in badminton players was different from the 1000 genome database for the European population (χ2 = 15.5; p < 0.001), with an overrepresentation of the RR genotype (p < 0.05) and an underrepresentation of the RX genotype (p < 0.01). In conclusion, the expression of functional α-actinin-3, associated with RR and RX genotypes in the ACTN3 gene may confer an advantage for reaching the status of elite athlete in badminton, and especially the world's top-ten ranking. Large-scale studies with different ethnic backgrounds are needed to confirm the association of the R allele of ACTN3 with badminton performance.

Elite Badminton Is Getting Older: Ages of the Top 100 Ranked Badminton Players from 1994 to 2020.

The purpose of this study was to determine the evolution of the age of badminton players in the top 100 of the World Ranking for men and women from 1994 to 2020. Data were collected from badminton players participating in the top 100 World Rankings (4800 entries: 1233 players; 595 men and 638 women) from 1994 to 2020. The mean age of the top 100 and the average highest ranking of the players were analysed for both genders. The mean age of the male players in the World Ranking increased from 23.7 ± 3.2 years in 1994 to 26.3 ± 4.4 years in 2020 (p < 0.001) and in female players, from 22.8 ± 3.8 years in 1994 to 24.7 ± 3.3 years in 2020 (p < 0.001). In addition, women recorded a younger age at entry into the top 100 and when reaching their best ranking. Additionally, there has been a clear increase in Asian players in the top 100 of the World Ranking in recent years, reaching over 60%. These data could be used to develop and organise training plans in this sport, optimising and maximising players' performance.

Effect of 12 Weeks Core Training on Core Muscle Performance in Rhythmic Gymnastics.

BACKGROUND: Rhythmic gymnastics performance is characterized by technical elements involving flexibility, aerobic capacity and strength. Increased core strength in rhythmic gymnastics could lead to improved sporting performance. OBJECTIVE: The aim of this study was to analyze the effect of 12 weeks of core muscle training on core muscle performance in rhythmic gymnasts. METHODS: A randomized controlled study involving 24 rhythmic gymnastics was conducted. Participants were randomly assigned to a control group (CG; n = 12; age 13.50 ± 3.17 years) or a training group (TG; n = 12; age 14.41 ± 2.35 years). Body composition, isometric strength of trunk, core endurance and core muscle electromyographic activity were measured (EMG) after 12 weeks of core training. Independent sample t-tests were carried out to compare baseline values between groups. A two-way repeated-measures analysis of variance (ANOVA) (time × group) was applied. RESULTS: The TG improved body composition, trunk lean mass (mean differences MD = -0.31; p = 0.040), lean mass (MD = 0.43; p = 0.037) and bone mass (MD = -0.06; p < 0.001) after training. Core training increased isometric strength of trunk, flexion test (MD = -21.53; p = 0.019) and extension test (MD = 22.7; p = 0.049), as well as the prone bridge core endurance test (MD = -11.27; p = 0.040). The EMG values also increased in the TG in prone bridge for front trunk (MD = -58.58; p = 0.026). CONCLUSIONS: Core strength training leads to improvements in body composition, as well as improvements in trunk strength and increases in muscle electromyographic activity. These improvements could therefore improve performance during competitive rhythmic gymnastics exercises.

AIR-BT, a new badminton-specific incremental easy-to-use test.

BACKGROUND: Badminton is a highly demanding sport characterized by intermittent efforts with energy being provided by both the aerobic and anaerobic systems. To date, no incremental badminton field test has been developed that can be easily used by badminton coaches that requires accessible material for anyone. OBJECTIVES: The purpose of this study was to develop a practical and reliable easy-to use intermittent endurance badminton test for estimating maximal oxygen uptake (VO2max). METHODS: Thirty six Spanish badminton players (age: 24.1±10.3 years) performed, on different days of the same week, four incremental protocols to exhaustion in randomized order: a treadmill incremental test, a Yo-Yo intermittent recovery level 1 test (Yo-Yo IR1) and twice the Abian intermittent recovery badminton test (AIR-BT). Oxygen uptake was determined with a breath-by-breath gas analyzer during the incremental treadmill test, and performance in the Yo-yo IR1 and AIR-BT was recorded. RESULTS: Significant correlations (p<0.001) for Pearson's product moment coefficient were found between the performance in the AIR-BT and the two non-specific incremental tests (VO2max in the Treadmill Test: r = 0.87, distance in the Yo-Yo IR1: r = 0.86). The regression equation to calculate the VO2max from the AIR-BT time [VO2max = 0.023*(AIR-BT time in seconds)+31.334] showed an adjusted R2 of 0.76 and a SEE of 3.34 ml·kg-1·min-1. There was no significant difference between VO2max obtained by the incremental treadmill test and VO2max calculated using the regression equation (p = 0.644). A paired t-test reported no significant differences between day 1 and day 2 in the AIR-BT time (p = 0.753), the Pearson correlation coefficient between both days was: r = 0.88 (p<0.001) and the intraclass correlation coefficient was 0.875. CONCLUSIONS: The AIR-BT is a valid and reliable on-court test for assessing VO2max in badminton players and may be utilized by coaches and physical trainers for cross-sectional comparison of players and for evaluation of longitudinal changes.

Endurance running prevents the age-related decline of calcaneal bone stiffness.

This investigation presents a comparison of calcaneus bone stiffness of endurance runners of different ages and age-matched controls. We found that there was an age-associated decline in calcaneus bone stiffness in the control group while endurance runners prevented this decline, with a higher effect as the participants increased their age. PURPOSE: Previous investigations have found that endurance runners have higher bone mineral density and other bone quality variables in mechanically loaded bones. However, it is unknown if endurance running might counteract the decline in bone stiffness that occurs with age. The purpose of this study was to compare calcaneus bone stiffness of endurance runners of different ages to age-matched controls. METHODS: In a descriptive cross-sectional study, 182 endurance-trained male runners and 116 healthy untrained male controls underwent an ultrasonographic assessment of the calcaneus bone in the right and left heels. Calcaneal bone stiffness was calculated from assessments of the broadband ultrasound attenuation and the speed of sound. RESULTS: The line of best fit for the association between age and calcaneus stiffness was different between marathoners and controls (Z = - 2.1, P = 0.02). A two-way ANCOVA (condition × age) with body mass, and body mass index as covariates, revealed that there were main effects of condition (F = 26.8, P < 0.01) and age (F = 4.2, P < 0.01) for calcaneus stiffness, with a significant interaction between these two factors (F = 2.8, P = 0.03). The post hoc analysis revealed that calcaneus stiffness was significantly higher in marathoners of 40-44 years (121.5 ± 18.2 vs 101.1 ± 21.3 arbitrary units [A.U.], P = 0.01), 45-49 years (121.5 ± 19.7 vs 104.3 ± 13.4 A.U., P = 0.04), and > 50 years (111.2 ± 17.9 vs 92.4 ± 16.0 A.U., P < 0.01) than their untrained counterparts of the same age with no statistically significant differences in the remaining age groups. CONCLUSION: Endurance runners of > 40 years had higher values of calcaneus stiffness than controls, providing evidence to support the potential effect of endurance running to reduce the age-related decline on calcaneus bone stiffness.

Effects of Cross-Education After 6 Weeks of Eccentric Single-Leg Decline Squats Performed With Different Execution Times: A Randomized Controlled Trial.

BACKGROUND: Cross-education of strength refers to the strength gain that is transferred to the contralateral limb after a unilateral training program. HYPOTHESIS: Unilateral eccentric training using different muscle contraction times would improve the structural and functional properties of the untrained contralateral limb. STUDY DESIGN: Randomized controlled trial. LEVEL OF EVIDENCE: Level 2. METHODS: Thirty-six participants were randomized into a control group, experimental group 1 (EG6s; eccentric contraction runtime = 6 seconds) and experimental group 2 (EG3s; eccentric contraction runtime = 3 seconds). The thickness and elastographic index of the patellar tendon (PT), lean mass and fat percentage of the thigh, contractile properties of the vastus lateralis (VL), as well as isometric, concentric, and eccentric knee extensor peak torques, and eccentric single-leg decline squat (SLDSe) 1 repetition maximum (1-RM) were measured after 6 weeks of SLDSe training (3 times per week, 80% of 1-RM) and after 6 weeks of detraining in the untrained contralateral limb. RESULTS: After training, there was an increase in lean thigh mass of the untrained limb in both groups: EG6s (0.17 ± 0.29 kg;P = 0.03; effect size [ES] = 0.15) and EG3s (0.15 ± 0.23 kg; P = 0.04; ES = 0.19). Likewise, both EG6s (62.30 ± 19.09 kg; P < 0.001; ES = 4.23) and EG3s (68.09 ± 27.49 kg; P < 0.001; ES = 3.40) increased their 1-RM, isometric (EG6s: 48.64 ± 44.82 N·m, P < 0.001, ES = 0.63; EG3s: 34.81 ± 47.30 N·m, P = 0.004, ES = 0.38), concentric at 60 deg/s and 180 deg/s and eccentric at 60 deg/s and 180 deg/s knee extensor peak torques (P < 0.05) in the untrained limb. However, no differences were found in the contractile properties of the VL or in the thickness of the PT after eccentric training in either of the 2 experimental groups. CONCLUSION: Regardless of the runtime of the contraction, 6 weeks of SLSDe was effective for inducing structural and strength adaptations in the contralateral untrained limb. However, most of these adaptations were lost after 6 weeks of detraining. CLINICAL RELEVANCE: Our study suggests that cross-education training can be of great importance for clinical application and musculoskeletal and neuromuscular rehabilitative processes after unilateral injury.

Objective Assessment of Regional Stiffness in Vastus Lateralis with Different Measurement Methods: A Reliability Study.

The objective of this study was to evaluate the reliability of four methods of assessing vastus lateralis (VL) stiffness, and to describe the influence of structural characteristics on them. The stiffness of the dominant lower-limb's VL was evaluated in 53 healthy participants (28.4 ± 9.1 years) with shear wave elastography (SWE), strain elastography (SE), myotonometry and tensiomyography (TMG). The SWE, SE and myotonometry were performed at 50%, and TMG was assessed at 30%, of the length from the upper pole of the patella to the greater trochanter. The thickness of the VL, adipose tissue and superficial connective tissue was also measured with ultrasound. Three repeated measurements were acquired to assess reliability, using intraclass correlation coefficients (ICC). Pearson's correlation coefficients were calculated to determine the relationships between methodologic assessments and between structural characteristics and stiffness assessments of the VL. Myotonometry (ICC = 0.93; 95%-CI = 0.89,0.96) and TMG (ICC = 0.89; 95%-CI = 0.82,0.94) showed excellent inter-day reliability whereas with SWE (ICC = 0.62; 95%-CI = 0.41,0.77) and SE (ICC = 0.71; 95%-CI = 0.57,0.81) reliability was moderate. Significant correlations were found between myotonometry and VL thickness (r = 0.361; p = 0.008), adipose tissue thickness (r = -0.459; p = 0.001) and superficial connective tissue thickness (r = 0.340; p = 0.013). Myotonometry and TMG showed the best reliability values, although myotonometry stiffness values were influenced by the structural variables of the supra-adjacent tissue.

Morphology of the Patellar Tendon and the Contractility Response of the Quadriceps: Symmetry and Gender Analysis.

The purpose of the study was to describe the differences between the dominant and non-dominant leg regarding contractility response and quadriceps strength and the morphology and stiffness of the patellar tendon (PT) in a group of physically active men and women. Fifty physically active subjects (36 men and 14 women) were evaluated for morphology and stiffness of the PT, contractility response of the rectus femoris of the quadriceps, isometric strength of the quadriceps and hamstrings, and isokinetic strength (concentric and eccentric) at 60°/s of the knee extensors. The measurements were made on the subject's dominant and non-dominant leg. The men showed a greater thickness of the PT in both legs compared to the women. Regarding the contractility response, the women recorded a 10.1 ± 16.2% (p = 0.038) greater contraction time (ct) in the dominant versus the non-dominant leg and the men recorded 11.9% (p = 0.040) higher values in the dominant leg compared to the women. In all the absolute strength measurements the men recorded higher values (p < 0.05) than the women, however, when the values were normalised with respect to the muscle mass of the leg these differences disappeared. The dominant leg showed values of isometric strength and eccentric strength at 60°/s (p < 0.05) greater than the non-dominant leg. The reference values provided in this study of the knee extensors and PT may be useful for detecting possible muscular or tendinous anomalies.

Structural and mechanical properties of the Achilles tendon in senior badminton players: Operated vs. non-injured tendons.

BACKGROUND: The aim of this study was to describe the differences in structural and mechanical properties between operated and non-injured Achilles tendons in senior badminton players who had had Achilles tendon surgery and had returned to play. METHODS: Eighteen players (age = 48.9(10.0)years), assigned to the unilateral Achilles tendon rupture group and 177 non-injured players (age = 55.4(9.4)years), assigned to the control group. A Logiq®S8 ultrasound was used to study tendon structure and elastography index values and a Myoton®PRO hand-held myotonometer was used to record the stiffness of the Achilles tendon. FINDINGS: In Achilles tendon rupture group, operated tendons showed higher values than non-injured ones in thickness (Operated = 9.03(2.67)mm vs. non-injured = 5.88(0.88)mm; P < 0.001), width (Operated = 18.44(3.20)mm vs. non-injured = 16.80(1.97)mm; P = 0.039), cross sectional area (Operated = 140.33(60.29)mm2 vs. non-injured = 74.40(17.09)mm2; P < 0.001) and elastography index (Operated = 2.05(1.35)A.U. vs. non-injured = 1.47(0.62)A.U.; P = 0.025). The bilateral differences shown by the Achilles tendon rupture group were greater than the bilateral differences shown by the control group for thickness (P < 0.001), width (P = 0.001), cross sectional area (P < 0.001), tone (P = 0.006) and dynamic stiffness (Achilles tendon rupture group = 10.85(23.90)N∙m-1. vs. control group = 0.18(18.83)N∙m-1; P = 0.031). INTERPRETATION: Surgery on the Achilles tendon and adaptation to the mobilisation and strength training during rehabilitation could provoke structural and mechanical differences compared to the non-injured tendon. Furthermore, the differences between both Achilles tendons in the Achilles tendon rupture group was higher than the asymmetry observed between dominant and non-dominant Achilles tendons in the control group. In addition, the higher logarithmic decrement values showed by non-injured tendons in the Achilles tendon rupture group could be a tendinous injury risk factor.