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PERFORMANCE GAINS IN RELAY SWIMMING (PART II) – THE MOTIVATION GAINS COMPONENT
Get PDFThe purpose of this study was to test whether swimmers become further motivated by swimming in a relay team compared to swimming on their own, which results in increased performance. Particularly, we assume that this increased motivation results in a performance that even exceeds their best performance achieved in individual competitions (their personal best). However, because the often-observed performance gains in relay swimming are the sum of relay start benefits and increased motivation caused by teamwork it is necessary to determine the advantage that is caused by a relay start (Fischer, 2017; Qiu et al., 2021) to accurately evaluate relay versus individual performances. But to date, the proportion of these two components remains unclear. The results of the current research show that most of the fastest swimmers from the last 20 years swam faster in a relay race. Thus, they exceeded their personal best (from an individual race) in a relay race due to the social influences of the team membership. Furthermore, the share of the performance that is due to increased motivation is markedly larger than that of the relay start benefit. This study is the first quantifying the motivation gains component in relay swimming
INFLUENCE OF TRUNK EXTENSION TECHNIQUE ON PERFORMANCE AND CORE STABILITY DURING ERGOMETER ROWING
Get PDFThis study had for purpose to evaluate the impact of using a different timing of trunk extension on performance parameters and on core stability during ergometer rowing. 16 expert rowers took part in this study. Each subject rowed with 3 different trunk extension timings on a RowPerfect 3. An early trunk extension technique was detrimental to performance and induced more activity of trunk extensors. The usual legs-trunk-arms kinematics sequence seems to be more performant despite not being the least demanding on core stability
PREDICTORS OF PELVIC ACCELERATION DURING TREADMILL RUNNING AT DIFFERENT STRIDE FREQUENCIES
Get PDFThe aim of this study was to examine predictors of peak vertical and anteroposterior pelvic acceleration during treadmill running. Participants ran at 9 km∙h-1 at their preferred stride frequency and at ± 5% of their preferred stride frequency. Coordinate and acceleration data were collected using a motion capture system and inertial measurement units. Linear mixed models showed that for every one standard deviation increase in the anteroposterior displacement from knee to ankle at initial contact, vertical pelvic acceleration increased by 2.18 m∙s-2 (p = 0.046). Additionally, for every one standard deviation increase in stride frequency, peak anteroposterior pelvic acceleration increased by 0.68 m∙s-2 (p = 0.035). Runners who suffer from injuries or pain at the pelvis may benefit from decreasing the anteroposterior displacement from their knee to their ankle at initial contact and reducing their stride frequency
SURFACE MEASURED ACCELERATIONS DURING CRICKET FAST-BOWLING
Get PDFThe aim of this research was to quantify the magnitude and timing of surface measured accelerations during the fast-bowling action. Eleven males performed 6 maximum velocity deliveries with accelerometers positioned over: both ankles; knees; hips; L5; L1; and the C7 vertebrae. Accelerometer signals exhibited decreased peak and increased time to peak acceleration from the ankle to the C7 sensor. Even when distal accelerations were largest at front foot contact, the body was still able to dissipate more than 90% of the acceleration. Active and passive mechanisms such as joint compliance and spinal compression within the body therefore likely contribute to the progressive attenuation of accelerations. The effects of such compliance on investigations of the intersegmental forces and moments during cricket fast-bowling via inverse dynamics warrants further investigation.
KEYWORDS: accelerometer, attenuation, inertial measurement unit, ground reaction force
CAN A SIMPLIFIED KNEE ABDUCTION MOMENT ESTIMATION BE USED FOR ATHLETE SCREENING? IMPLICATIONS FOR ACL INJURY PREVENTION
Get PDFThis study aimed to compare a simplified calculation of the knee abduction moment with the traditional inverse dynamics calculation when athletes perform fake-cut maneuvers with different complexities. In the simplified calculation, we multiply the force vector with its lever arm to the knee, projected onto the local coordinate system of the proximal thigh, hence neglecting the inertial contributions from distal segments. We found very strong ranking consistency using Spearman’s rank correlation coefficient when using the simplified method compared to the traditional calculation. Independent of the tasks, the simplified method resulted in higher moments than the inverse dynamics. This was caused by ignoring the moment caused by segment linear acceleration generating a counteracting moment by about 7%. An alternative to the complex calculations of inverse dynamics can be used to investigate the contributions of the GRF magnitude and its lever arm to the knee
COMPARISON OF INDIVIDUAL MUSCLE CONTRIBUTIONS TO GROUND REACTION FORCES DURING JUMP AND CHANGE OF DIRECTION TESTING AFTER ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION
Get PDFThe purpose of this study was to identify the main muscle contributions across a battery of different tasks commonly used to evaluate an athlete’s readiness to return to sport after anterior cruciate ligament injury (ACL) and following ACL reconstruction. These injuries are mostly related to landing and change of direction movements and, due to its high incidence, efforts must be made to better understand the knee soft tissue mechanisms during these types of tasks. Data from a single athlete were analysed for this study. Scaled generic musculoskeletal models, consisting of 12 segments, 23 degrees of freedom and 92 musculotendon actuators were used in OpenSim. The quadriceps were the main contributors to ground reaction forces along the anterior/posterior direction, and, aided by the soleus and gastrocnemii, counteracted most of the effects applied by gravity along the vertical direction. The main contributors to the ground reaction forces during all the tasks are the same muscles that are intimately related to ACL loading, thus making these tasks useful for injury rehabilitation programs
EFFECTS OF AN EXTENSIVE RUNNING BOUT IN NOVICE FEMALE RUNNERS
Get PDFThe purpose of this study was to characterize the spatiotemporal, force, and subjective effects that occur during an extensive run in novice female runners. Foot sole pressure, rate of fatigue, and speed were recorded during a 45-min flat ecological run. No significant effects were found in spatiotemporal, force-time, or rate of fatigue responses outside of the initiation phase of the running bout. When participants were grouped according to their pacing strategy, those with a decreasing speed over time exhibited significant decreases in rate of force development as time progressed. Participants tended to decrease mechanical loading variables, and increase their rate of fatigue throughout the run. Future studies should investigate a larger number of subjects to determine if these tendencies are characteristic of novice female runners
THE EFFECT OF MEASUREMENT ANGLE ON APPROXIMATIONS OF MAXIMUM JOINT TORQUE
Get PDFThe purpose of this study was to investigate the underestimation of maximum knee joint torque using a single joint-angle position for a variety of realistic torque-angle curves. The maximum force production capability of the knee flexors and knee extensors was modelled using literature-based parameters to define a quadratic torque-angle relationship. Model parameters were varied within a normative range and simulated measured torque was compared to true peak torque (model) for a series of commonly tested joint angles. Measurements furthest from the optimal angle for maximum strength were associated with underestimated torques that were 96% and 80% lower than true peak torque. Therefore, it is essential that knee joint torque is measured as close to the optimal angle as possible when attempting to determine maximum strength capability using a single discrete measurement
EFFECTS OF POST-ACTIVATION POTENTIATION ENHANCEMENT ON JUMP ASYMMETRY USING BANDED SQUATS WITH PROFESSIONAL AMERICAN FOOTBALL PLAYERS
Get PDFUnderstanding the effects complex training has on symmetry could potentially supply practitioners with the knowledge to provide safe and effective training for their athletes. The purpose of this study was to determine the effects of post-activation potentiation enhancement (PAPE) using banded squats on symmetry during a countermovement jump (CMJ). Professional American football players (n=8) performed four trials of CMJs on dual force plates to record limb asymmetry and jump height with a set of heavy banded squats between each trial to ensure a potentiation effect was present. There were no significant changes in asymmetry across the 4 trials, p\u3e.05. However, jump height did significantly improve F(3,21) = 3.69, p=0.028. Banded squat training has no effect on jump symmetry
ANALYSIS OF A LATERAL ANKLE SPRAIN INJURY IN BADMINTON WITH A MODEL-BASED IMAGE-MATCHING FORENSIC VIDEO ANALYSIS METHOD
Get PDFAbstract
The purpose of this study was to examine the kinematics of an acute lateral ankle sprain sustained during a televised badminton match. A clip of an acute lateral ankle injury sustained during a match was edited and imported into Poser 4 and Poser Pro Pack to match the badminton court ground line and the player\u27s skeletal model. Internal rotation rose with time and peaked at 57° at 0.28s, plantarflexion peaked at 22° at 0.08s and subsequently decreased, and inversion peaked at 92° at 0.2s. The maximal plantarflexion, internal rotation, and angular velocity of internal rotation were 492°/s, 921°/s, and 969°/s, respectively. After the strike, the ankle injury developed as a result of ankle inversion and internal rotation motions. To reduce ankle injuries in badminton, players should maintain a regulated landing posture while adjusting for environmental conditions and increase their strength and conditioning training on landing skills.
KEYWORDS: acute lateral ankle sprain; biomechanics; injury preventio