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THE EFFECT OF MUSCLE STRENGTH NORMALIZATION PROCEEDURES ON DECISIONS TO RETURN TO SPORT
Get PDFThe objective of this study was to evaluate different methods of normalizing and reporting muscle strength for making decisions about return to sport following an anterior cruciate ligament injury. 42 participants performed 5 isometric knee extensions on an isokinetic dynamometer. The peak force as well as the rate of torque development were determined and expressed either as the average of 4 trials or the peak value. In addition, the limb symmetry index was determined for each condition and compared. Using the peak method resulted in significantly higher values (
A PILOT STUDY ASSESSING EFFECTS OF TAPING THE ANKLE TENDONS ON POSTURAL CONTROL UNDER UNPREDICTABLE PERTURBATION
Get PDFUnpredictable external perturbation significantly degrades balance and increases the risk of falls, so methods to improve postural control under such perturbation are expected to be beneficial. Considering the important role of somatosensory feedback from ankle tendons in balance regulation, we proposed that applying adhesive elastic tapes to the ankle tendons may affect the postural control. In this initial pilot study, we recruited four healthy young adults and instructed them to balance under forward and backward perturbation which was applied at unpredictable timing by an electrically controlled actuator. The task was performed with and without the application of tapes. We found that cutaneous stimulation to the ankle tendons significantly reduced the peak displacement of the center of pressure (p = 0.008), and changed activations of multiple muscles (gastrocnemius medialis: p = 0.041, biceps femoris: p = 0.023, and erector spinae: p = 0.035) under forward direction perturbation. In contrast, no significant difference was observed under backward direction perturbation. Our findings suggest that cutaneous stimulation by applying adhesive elastic tapes can affect the postural control under unpredictable external perturbation, but its effect may depend on the direction of the perturbation
EXPLORING DIFFERENCES IN ELECTROMYOGRAPHY AND GROUND REACTION FORCES BETWEEN FRONT AND BACK SQUATS BEFORE AND AFTER A FATIGUING PROTOCOL
Get PDFLimited research has been conducted to explore differences in biomechanical and physiological demands of the front and back squat, especially in response to fatigue where technique may be altered. This study investigated differences in electromyography and ground reaction forces during a 3-repetition maximum back and front squat before and after a fatiguing protocol in 30 males. Mean and peak activation of the semitendinosus was greater in the back squat than the front squat (p \u3c 0.05). There were no differences in quadricep activation between back and front squats. There were no differences in electromyography as a result of fatigue, however, force production decreased for back squats following fatigue (p \u3c 0.01). This research disputed the notion that front squats have a greater quadricep focus, however lends support to the hypothesis that quadricep activation equal to the back squat can be achieved with lighter absolute load in a front squat. The finding of lower ground reaction forces for the back squat following the fatiguing protocol in addition to no differences in electromyography between front and back squats indicates greater effects of the fatiguing protocol on back squat performance
THE USE OF INERTIAL MEASUREMENT UNITS TO IDENTIFY BIOMECHANICAL FACTORS OF PERFORMANCE IN CRICKET FAST BOWLERS
Get PDFThe role of a cricket bowler is to deliver the ball in such a way as to minimise batsmen scoring runs or get them out. Fast bowlers utilise the pace of delivery as a key tool to achieve this. The purpose of this study was to use inertial measurement units (IMUs) to investigate the relationship between IMU derived spinal kinematics, lower limb accelerations and ball release speed in cricket fast bowlers. Sacral vertical loading rate at back-foot impact and thoracic lateral flexion at front-foot impact displayed significant positive relationships with ball release speed (r=.521 and .629 respectively). Consequently, this study highlights IMUs are able to effectively identify trends in fast bowling performance and hence, larger accelerations at back-foot impact with increased lateral flexion at front-foot impact were effective strategies to increase ball release speed for the bowlers measured in this study
ASSOCIATIONS BETWEEN EXERCISE-INDUCED FLATTENING OF FOOT ARCH AND FATIGUE OF EXTRINSIC AND INTRINSIC FOOT MUSCLES
Get PDFWe aimed to examine the associations between exercise-induced flattening of the foot arch and fatigue of extrinsic and intrinsic foot muscles. Fifteen male participants repeated 100 hops/set until they could no longer maintain the hop frequency or had completed 30 sets. The sagittal plane range of motion (ROM) of the midfoot during stance phase significantly decreased at the final set compared to the initial set (-8.8°). After the fatigue task, MRI T2 relaxation time in all measured extrinsic and intrinsic foot muscles significantly increased (17.2‒37.4%); however, only its increase in the tibialis posterior (TP) correlated with the relative change in midfoot ROM (r = 0.684). These results suggest that fatigue of TP is associated with the occurrence of flattening of the foot arch. This study provides a clinical implication that monitoring midfoot kinematics can be used to assess the condition of TP
KINETIC STRATEGIES OF GYMNASTICS LANDINGS
Get PDFOrganisation and magnitude of lower limb kinetics during landing can contribute to knowledge of injury. Our aim was to quantify leg stiffness and temporal organisation of joint moments of two different landing styles. Four female gymnasts performed 20 landings in the women’s and men’s landing style. Synchronised kinematic (250 Hz) and kinetic (1000 Hz) data were used to describe the leg and joint stiffness, and the sequencing of the peak joint moments. Leg stiffness demonstrated lower variability compared to the associated joint level, suggesting joint level control. Group relative timing of the lower extremity joint moments presented distal-proximal sequencing, although individuals presented a variety of landing strategies. This study highlights the individualised signature strategies in landing, and consequently the importance of a single-subject design when examining injury risk
THE VALIDITY OF MEASURING SKIPPING CADENCE WITH A NOVEL WEARABLE SENSOR - SINTEC SMART PATCH
Get PDFThe aim of this study was to test the validity of running cadence assessed with a novel smart patch designed within a SINTEC Horizon 2020 project. Participants performed 3 consecutive 20-seconds skipping with increasing intensity (slow, medium, fast). Cadence was derived from raw data from a “SINTEC” smart patch, Dytran accelerometers, and HBM bilateral force plates. Data from all devices were compared using Bland-Altman analysis and Wilcoxon signed-rank test. The mean bias between cadence measured with Dytran accelerometer and force plates with ‘’SINTEC’’ smart patch was 0.08 and -0.17 steps/min, respectively. In addition, there were no statistically significant difference between the mean cadence determined with different sensors/devices. Therefore, we can conclude that the measurement of cadence using a novel SINTEC smart patch showed good validity
EFFECTS OF SHOD AND BAREFOOT RUNNING ON THE IN VIVO KINEMATICS OF THE FIRST METATARSOPHALANGEAL JOINT
Get PDFThe purpose of this study is to investigate the differences of the first metatarsophalangeal joint’s 6 degree-of-freedom (6DOF) kinematics during shod and barefoot conditions by using a high-speed dual fluoroscopic imaging system (DFIS). Fifteen healthy male runners were recruited. Computed tomography (CT) scans were taken of each participant’s right foot for the construction of 3D models and local coordinate system. The fluoroscopic images of the right foot during the stance period were acquired under shod and barefoot condition with rearfoot strike pattern Radiographic images were acquired at 100 Hz while the participants ran at a speed of 3±5% m/s in a track and 6DOF kinematics were calculated by 2D-3D registration. Paired sample t-test was used to compare the kinematic characteristics of the first MTPJ 6DOF kinematics between shod and barefoot. Compared with barefoot, wearing shoes 1) decreased the peak medial, posterior, and superior translation of the first MTPJ during stance (P ＜ 0.05); 2) decreased maximum extension angle, minimum extension angle, and flexion/extension range of motion of the first MTPJ during stance (P ＜ 0.05); 3) increased minimum adduction angle of the first MTPJ during stance (P ＜ 0.05). It suggests that shoes may affect the function of the first MTPJ and increase the risk of hallux valgus. Our study makes up for the deficiency of traditional motion measurement methods that only focus on the sagittal flexion and extension movement of the first MTPJ and provides a more comprehensive understanding of the potential relationship between joint motion and injurie
A COMPARISON OF UNMATCHED AND MATCHED FILTERING APPROACHES FOR KNEE JOINT STIFFNESS CALCULATION DURING RUNNING
Get PDFThis study compared typical measures of knee joint moment, angle and stiffness in eight recreational runners during distance running after digitally filtering ground contact force and lower limb motion data using 20-20 Hz and 50-8 Hz cut-off frequencies, respectively. The matched 20 Hz approach clearly removed some higher frequency oscillation signals in the knee moment curves and produced a better linear regression fit to calculate joint stiffness from the knee moment-angle relationship. However, knee joint stiffness values over the first half of running stance were no different between the two filtering approaches. It remains to be determined whether improved linear fit can lead to greater sensitivity in the joint stiffness estimations to detect changes that may result from factors such as fatigue or footwear interventions
Marx, Critical Theory, and the Treadmill of Production of Value: Why Environmental Sociology Needs a Critique of Capital
Get PDFThis chapter explores the domestication of Marx’s critique of political economy within Marxist-oriented environmental sociology, and treadmill of production (ToP) theory, in particular. The aim is to explicate the theoretical resources for a rigorous critique of capital-induced planetary degradation. Shortcomings of ToP theory pertaining to the conceptualization of capital and value are identified. The reasons for these shortcomings, including how they might be addressed, are elaborated by reconsidering key aspects of Marx’s critical theory of modern capitalist society. The chapter contributes to current discussions in both critical theory and environmental sociology by demonstrating the continued relevance of Marx’s critical theory for understanding the political-economic, social, and ideational dimensions of planetary degradation. In contrast to ToP theory, which critically examines the production of wealth by counterposing finitude and limits against the expansionary tendencies of economic growth, the critical theory approach advanced in this chapter conceptualizes the acceleration of environmental degradation following World War II in terms of a ToP of value, whereby the necessity of the value form is continuously established in the present. The chapter discusses how Marxian critical theory facilitates a critical examination of the widespread growth of environmentalism as concomitant with the spread of neoliberal capitalism