Description:
Aim To critically review the evidence to determine the efficacy and effectiveness of protective equipment, rule changes, neck strength and legislation in reducing sport concussion risk. Methods Electronic databases, grey literature and bibliographies were used to search the evidence using Medical Subject Headings and text words. Inclusion/ exclusion criteria were used to select articles for the clinical equipment studies. The quality of evidence was assessed using epidemiological criteria regarding internal/external validity (eg, strength of design, sample size/power, bias and confounding). Results No new valid, conclusive evidence was provided to suggest the use of headgear in rugby, or mouth guards in American football, significantly reduced players' risk of concussion. No evidence was provided to suggest an association between neck strength increases and concussion risk reduction. There was evidence in ice hockey to suggest fair-play rules and eliminating body checking among 11-years-olds to 12-years-olds were effective injury prevention strategies. Evidence is lacking on the effects of legislation on concussion prevention. Equipment self-selection bias was a common limitation, as was the lack of measurement and control for potential confounding variables. Lastly, helmets need to be able to protect from impacts resulting in a head change in velocities of up to 10 and 7 m/s in professional American and Australian football, respectively, as well as reduce head resultant linear and angular acceleration to below 50 g and 1500 rad/s2, respectively, to optimise their effectiveness. Conclusions A multifactorial approach is needed for concussion prevention. Future well-designed and sportspecific prospective analytical studies of sufficient power are warranted.
Description:
Objective: To identify risk factors for injury to cricket fast bowlers using field-based tests. Design: Prospective cohort study. Setting: High performance Australian cricket. Participants: Ninety-one male adolescent and adult fast bowlers (aged 12-33 years). Assessment of risk factors: A field-based pre-participation screening, consisting of musculoskeletal, fitness and anthropometric assessments and analysis of bowling technique was undertaken. Bowlers were prospectively monitored over the 2003-4 season and bowling workload and injuries were recorded. Logistic regression was used to identify injury risk factors. Main outcome measurement: Repetitive microtrauma injury to the trunk, back or lower limb associated with fast bowling. Results: Two variables were identified as independent predictors of injury in the multivariate logistic regression analysis. Bowlers with hip internal rotation of <= 30 degrees on the leg ipsilateral to the bowling arm were at a significantly reduced risk of injury (OR 0.20, 95% CI 0.06 to 0.73) compared with bowlers with >40 degrees of rotation. Bowlers with an ankle dorsiflexion lunge of 12.1-14.0 cm on the leg contralateral to the bowling arm were at a significantly increased risk (OR 4.03, 95% CI 1.07 to 15.21) than bowlers with a lunge of >14 cm. Bowlers with a lunge of (12 cm were also at an increased risk, but not significantly so (OR 1.38, 95% CI 0.40 to 4.84). Conclusions: Biomechanical research is needed to investigate how these two intrinsic risk factors increase injury risk so that appropriate interventions can be developed.
Description:
Training for muscle hypertrophy can be expected to induce some increase in total body mass, and this can have positive or negative consequences for athletic performance. Positive effects may be increased strength, increased resistance to being pushed aside, and greater momentum when running, whereas possible negative effects may be reduced capacity to accelerate, decelerate, change direction, and jump. These possible effects of gaining muscle and total body mass suggest that strength and conditioning coaches should give thoughtful consideration to the amount of hypertrophy training prescribed throughout an athletes's development and should be determined by the specific needs of the athlete.
Description:
TRAINING FOR MUSCLE HYPERTROPHY CAN BE EXPECTED TO INDUCE SOME INCREASE IN TOTAL BODY MASS, AND THIS CAN HAVE POSITIVE OR NEGATIVE CONSEQUENCES FOR ATHLETIC PERFORMANCE. POSITIVE EFFECTS MAY BE INCREASED STRENGTH, INCREASED RESISTANCE TO BEING PUSHED ASIDE, AND GREATER MOMENTUM WHEN RUNNING, WHEREAS POSSIBLE NEGATIVE EFFECTS MAY BE REDUCED CAPACITY TO ACCELERATE, DECELERATE, CHANGE DIRECTION, AND JUMP. THESE POSSIBLE EFFECTS OF GAINING MUSCLE AND TOTAL BODY MASS SUGGEST THAT STRENGTH AND CONDITIONING COACHES SHOULD GIVE THOUGHTFUL CONSIDERATION TO THE AMOUNT OF HYPERTROPHY TRAINING PRESCRIBED THROUGHOUT AN ATHLETE'S DEVELOPMENT AND SHOULD BE DETERMINED BY THE SPECIFIC NEEDS OF THE ATHLETE.
Description:
Training for muscle hypertrophy can be expected to induce some increase in total body mass, and this can have positive or negative consequences for athletic performance. Positive effects may be increased strength, increased resistance to being pushed aside, and greater momentum when running, whereas possible negative effects may be reduced capacity to accelerate, decelerate, change direction, and jump. These possible effects of gaining muscle and total body mass suggest that strength and conditioning coaches should give thoughtful consideration to the amount of hypertrophy training prescribed throughout an athletes's development and should be determined by the specific needs of the athlete.
Description:
TRAINING FOR MUSCLE HYPERTROPHY CAN BE EXPECTED TO INDUCE SOME INCREASE IN TOTAL BODY MASS, AND THIS CAN HAVE POSITIVE OR NEGATIVE CONSEQUENCES FOR ATHLETIC PERFORMANCE. POSITIVE EFFECTS MAY BE INCREASED STRENGTH, INCREASED RESISTANCE TO BEING PUSHED ASIDE, AND GREATER MOMENTUM WHEN RUNNING, WHEREAS POSSIBLE NEGATIVE EFFECTS MAY BE REDUCED CAPACITY TO ACCELERATE, DECELERATE, CHANGE DIRECTION, AND JUMP. THESE POSSIBLE EFFECTS OF GAINING MUSCLE AND TOTAL BODY MASS SUGGEST THAT STRENGTH AND CONDITIONING COACHES SHOULD GIVE THOUGHTFUL CONSIDERATION TO THE AMOUNT OF HYPERTROPHY TRAINING PRESCRIBED THROUGHOUT AN ATHLETE'S DEVELOPMENT AND SHOULD BE DETERMINED BY THE SPECIFIC NEEDS OF THE ATHLETE.
Description:
Objective: To identify studies that report three-dimensional (3D) biomechanical analysis of jump-landing tasks in relation to athletes with current patellar tendinopathy (PT), and/or asymptomatic with history of PT or patellar tendon abnormality (PTA) on diagnostic imaging. Methods: Five electronic databases were searched. Included articles were required to: (1) investigate the 3D biomechanics of a jump-landing task; (2) be cross-sectional or longitudinal in design; and (3) include participants that had symptomatic PT, were asymptomatic with a history of PT, asymptomatic with PTA on diagnostic imaging and/or asymptomatic with an unknown pathology or PT history. Results: Thirty-seven statistically significant jump-landing variables were associated with PT, history of PT and/or PTA. The only consistent variable that could be replicated between studies was knee flexion angle at initial foot-ground contact (IC) and an altered hip flexion/extension strategy during a horizontal land phase of a vertical stop-jump. Conclusion: Isolated vertical landings or take-offs alone may not be sensitive enough to identify key jump-landing variables associated with PT, thus clinicians and researchers should incorporate a whole jump-landing task with a horizontal landing component. Sagital plane hip and knee kinematics in a horizontal landing phase appear to provide the most valuable information for evaluating those with PT. (C) 2020 Elsevier Ltd. All rights reserved.
Description:
Some occupational health and safety hazards associated with sheep shearing are related to shearing shed design. One aspect is the floor of the catching pen, from which sheep are caught and dragged to the shearing workstation. Floors can be constructed from various materials, and may be level or gently sloping. An experiment was conducted using eight experienced shearers as participants to measure the force exerted by a shearer when dragging a sheep. Results showed that significant changes in mean dragging force occurred with changes in both surface texture and slope. The mean dragging forces for different floor textures and slopes ranged from 359 N (36.6 kg) to 423N (43.2 kg), and were close to the maximum acceptable limits for pulling forces for the most capable of males. The best floor tested was a floor sloped at 1:10 constructed of timber battens oriented parallel to the path of the drag, which resulted in a mean dragging force 63.6N (15%) lower than the worst combination.
Description:
Objective: To describe the physiological responses to tournament tennis in relation to prevailing environmental conditions, match notation, and skills that underpin performance. Design: 14 male professional tennis players (mean (SD) age, 21.4 (2.6) years; height, 183.0 (6.9) cm; body mass, 79.2 (6.4) kg) were studied while contesting international tennis tournaments. Environmental conditions, match notation, physiological (core temperature, hydration status, heart rate, blood variables), and performance indices (serve kinematics, serve velocity, error rates) were recorded. Results: Hard and clay court tournaments elicited similar peak core temperature (38.9 (0.3) v 38.5 (0.6)°C) and average heart rate (152 (15) v 146 (19) beats/min) but different body mass deficit (1.05 (0.49) v 0.32 (0.56)%, p<0.05). Average pre-match urine specific gravity was 1.022 (0.004). Time between points was longer during hard court matches (25.1 (4.3) v 17.2 (3.3) s, p<0.05). Qualitative analysis of first and second serves revealed inverse relations between the position of the tossing arm at ball release and the position of the ball toss and progressive match time (respectively, r= -0.74 and r= -0.73, p<0.05) and incurred body mass deficit (r=0.73 and r=0.73, p<0.05). Conclusions: Participants began matches in a poor state of hydration, and experienced moderate thermoregulatory strain and dehydration during competition. These adverse physiological conditions may compromise performance and influence notational analyses.
Description:
It is important to understand factors contributing to and directly causing sports injuries to improve the effectiveness and safety of sports skills. The characteristics of injury events must be evaluated and described meaningfully and reliably. However, many complex skills cannot be effectively investigated quantitatively because of ethical, technological and validity considerations. Increasingly, qualitative methods are being used to investigate human movement for research purposes, but there are concerns about reliability and measurement bias of such methods. Using the tackle in Rugby union as an example, we outline a systematic approach for developing a skill analysis protocol with a focus on improving objectivity, validity and reliability. Characteristics for analysis were selected using qualitative analysis and biomechanical theoretical models and epidemiological and coaching literature. An expert panel comprising subject matter experts provided feedback and the inter-rater reliability of the protocol was assessed using ten trained raters. The inter-rater reliability results were reviewed by the expert panel and the protocol was revised and assessed in a second inter-rater reliability study. Mean agreement in the second study improved and was comparable (52-90% agreement and ICC between 0.6 and 0.9) with other studies that have reported inter-rater reliability of qualitative analysis of human movement.
Description:
Traumatic brain injury (TBI) is the leading cause of death in alpine skiing. It has been found that helmet use can reduce the incidence of head injuries between 15% and 60%. However, knowledge on optimal helmet performance criteria in World Cup alpine skiing is currently limited owing to the lack of biomechanical data from real crash situations. Purpose: This study aimed to estimate impact velocities in a severe TBI case in World Cup alpine skiing. Methods: Video sequences from a TBI case in World Cup alpine skiing were analyzed using a model-based image matching technique. Video sequences from four camera views were obtained in full high-definition (1080p) format. A three-dimensional model of the course was built based on accurate measurements of piste landmarks and matched to the background video footage using the animation software Poser 4. A trunk-neck-head model was used for tracking the skier's trajectory. Results: Immediately before head impact, the downward velocity component was estimated to be 8 m.s(-1). After impact, the upward velocity was 3 m.s(-1), whereas the velocity parallel to the slope surface was reduced from 33 m.s(-1) to 22 m.s(-1). The frontal plane angular velocity of the head changed from 80 radIsj1 left tilt immediately before impact to 20 rad.s(-1) right tilt immediately after impact. Conclusions: A unique combination of high-definition video footage and accurate measurements of landmarks in the slope made possible a high-quality analysis of head impact velocity in a severe TBI case. The estimates can provide crucial information on how to prevent TBI through helmet performance criteria and design.
Description:
Traumatic brain injury (TBI) is the leading cause of death in alpine skiing. It has been found that helmet use can reduce the incidence of head injuries between 15% and 60%. However, knowledge on optimal helmet performance criteria in World Cup alpine skiing is currently limited owing to the lack of biomechanical data from real crash situations. Purpose: This study aimed to estimate impact velocities in a severe TBI case in World Cup alpine skiing. Methods: Video sequences from a TBI case in World Cup alpine skiing were analyzed using a model-based image matching technique. Video sequences from four camera views were obtained in full high-definition (1080p) format. A three-dimensional model of the course was built based on accurate measurements of piste landmarks and matched to the background video footage using the animation software Poser 4. A trunk-neck-head model was used for tracking the skier's trajectory. Results: Immediately before head impact, the downward velocity component was estimated to be 8 m.s(-1). After impact, the upward velocity was 3 m.s(-1), whereas the velocity parallel to the slope surface was reduced from 33 m.s(-1) to 22 m.s(-1). The frontal plane angular velocity of the head changed from 80 radIsj1 left tilt immediately before impact to 20 rad.s(-1) right tilt immediately after impact. Conclusions: A unique combination of high-definition video footage and accurate measurements of landmarks in the slope made possible a high-quality analysis of head impact velocity in a severe TBI case. The estimates can provide crucial information on how to prevent TBI through helmet performance criteria and design.
Description:
The power clean and other weightlifting movements are commonly used in the development of muscle power. However, there is a paucity of research examining the use of the hook grip (HG) in weightlifting performance. Therefore, the purpose of this study was to compare 1-repetition maximum (1RM) and kinetic, kinematic, and qualitative variables across a range of loads (75-100%) during power-clean performance with an HG and a closed grip. A total of 11 well-trained men (power-clean 1RM = 113.4 [15.9] kg, 1.34 × body mass) with at least 3 mo of HG experience volunteered to participate. Following a familiarization session, 1RM testing with the HG and closed grip were completed 5-7 d apart in a randomized order. Barbell kinetic and kinematic variables were recorded via a force platform and dual linear position transducer system. All subjects had a greater 1RM with the HG than with the closed grip (P < .001, effect size [ES] = 0.43). Peak velocity (ES = 0.41-0.70), peak power (ES = 0.43-0.61), peak force (ES = 0.50-0.57), and catch height (ES = 0.40-0.96) were significantly greater (P < .05) when using the HG at all or most of the submaximal intensities. In addition, subjects reported significantly greater perceptions of grip security, power, and technical competency at submaximal but not maximal loads. Athletes and coaches who implement weightlifting movements in their physical preparation should adopt the HG where possible. Furthermore, researchers and sport scientists should control and report the grip type used when performing weightlifting-type movements.
Description:
In rehabilitation for neurological injuries, gravity compensation or deweighting of the upper limb is often performed, as it allows patients with limited muscle activities to realize movements. Deweighting cancels the gravitational effect of the human arm allowing the available muscle forces to produce acceleration, and thus movement of the arm. In robotic devices designed for rehabilitation, deweighting is performed by applying forces to the arm, either joint-by-joint (e.g., with exoskeletons) or at a single point (e.g., with end-effector-based manipulanda). This paper formulates the gravity compensation strategy for spatial (three-dimensional) manipulanda, considers the effect of the force applied by the robotic device on the generalized dynamics of the upper limb and critically evaluates the advantages and limitations of this approach. Additionally, the proposed strategy is validated on the EMU robot, designed with the emphasis on its dynamically transparent mechanical transmission to allow an impedance control approach. The configuration of the EMU robot used in this letter only has 3 degrees of actuation, making it underactuated with respect to the task of regulating a human arm up to the wrist modeled with 4 degrees of freedom. The underactuation resulted in an uncompensated gravity induced moment about the swivel angle axis, which is a line connecting the shoulder and wrist points of the human arm. The experimental validation demonstrates the effectiveness of the proposed gravity compensation technique in cancelling the effect of gravity on the user's arm.