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1.
J Sports Sci ; 38(9): 1053-1061, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32290783

RESUMO

The study aim was to investigate ball movement patterns using network analysis techniques, to compare between successful and unsuccessful outcomes and teams in the Australian Football League (AFL). This analysis focused on possession chains starting from a kick-in (n = 1,720), drawn from all games played in the 2015 AFL Premiership season (18 teams, 206 games). Player interactions were quantified using four network metrics: cluster coefficient, degree centrality, network density, and entropy. Three-way ANOVA with Tukey post hoc and ω2 effect sizes were calculated to assess whether differences existed between kick-in outcomes, ladder brackets, and match outcomes for each network metric. No significant differences were observed between ladder brackets or match outcomes for any network metric. More successful kick-in chains were characterised by lower density (ω2 = 0.26, large effect; F(9, 1678) = 66.6, p < 0.00) and higher entropy (ω2 = 0.17, large effect; F(9, 1678) = 39.6, p < 0.00). This suggests that chains resulting in successful kick-in outcomes exhibited lower interconnectedness, with a high number of players involved, and lower predictability in ball movement patterns. These findings have practical value for coaches and performance analysts and support further applications of network analysis in Australian football.


Assuntos
Desempenho Atlético/fisiologia , Comportamento Competitivo/fisiologia , Futebol/fisiologia , Austrália , Processos Grupais , Humanos , Movimento , Equipamentos Esportivos , Análise e Desempenho de Tarefas
2.
J Sports Sci ; 38(8): 945-952, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32172671

RESUMO

Modified sports, whereby equipment and rules are manipulated to facilitate skill performance, have been shown to promote skill learning and potentially increase participation. However, it is currently unexplored how key stakeholders - coaches and key figures working in National associations - who are critical stakeholders in implementing and delivering sport programmes, perceive modified sport. This study explored how tennis coaches and key figures working within tennis National associations perceived the impact of implementing a modified tennis campaign on participation and skill development in children and adults. Key figures and coaches around the world completed an online questionnaire. Both groups considered that modified tennis was positively associated with increasing and sustaining participation, skill learning, talent development and people's attitude towards tennis. Furthermore, participants thought that a rule change (i.e., use of a low-compression ball in children competitions) and the campaign's core messages (i.e., "serve, rally, score" and "easy, fun, and healthy") have been critical for the success of the campaign. These results support previous research on the positive impact of modified tennis on skill development and provide a further impetus on implementing modified sports to increase participation. Other sports can adopt similar strategies to improve their modified programmes.


Assuntos
Destreza Motora/fisiologia , Participação dos Interessados , Tênis/fisiologia , Adulto , Aptidão , Criança , Desenho de Equipamento , Humanos , Pessoa de Meia-Idade , Organizações , Percepção , Equipamentos Esportivos , Inquéritos e Questionários
3.
J Sports Sci ; 38(8): 886-896, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32122274

RESUMO

Spatio-temporal data in sport is increasing rapidly, however suitable statistical methods for analysing this data are underdeveloped. The current study establishes the need for spatial statistical methods, propose a Bayesian hierarchical model as an appropriate method for comparing spatial variables, and test this model across three spatial scales. The need for spatial statistical methods was established through the identification of spatial autocorrelation. This necessitated the use of a Bayesian hierarchical model to test for an association between spatial ball movement entropy and spatial effectiveness. Posterior distribution results showed a generally positive association such that increases in entropy were associated with increases in effectiveness. The strength and confidence of the associations were impacted by the spatial scale, with the 6 × 6 grid showing the most conclusive evidence of a positive relationship; the 4 × 4 grid was mostly positive, however with a large variation; and finally, the basket-centric scale results were less conclusive. The results of the current study demonstrate the suitability of a Bayesian hierarchical model for testing for associations or differences between spatial variables. With the increase in spatial analyses in sport, this study presents an appropriate statistical method for dealing with complex problems associated with spatial analyses.


Assuntos
Basquetebol/fisiologia , Basquetebol/estatística & dados numéricos , Teorema de Bayes , Entropia , Feminino , Humanos , Movimento , Análise Espacial , Equipamentos Esportivos
4.
Int J Sports Med ; 41(6): 419-423, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32045949

RESUMO

This study examined how the volume of trunk muscles and its bilateral asymmetry are related to club head speed in golfers. Fourteen right-handed male golfers performed five driver shots, and the club head speed for each trial was calculated from a three-dimensional reflective marker position of the club head immediately before impact. The volume of each side of the rectus abdominis, erector spinae, psoas major, quadratus lumborum, lateral abdominal wall muscle, and multifidus was determined using magnetic resonance imaging. For each muscle, the ratio of the larger to smaller side in muscle volume was calculated to assess bilateral asymmetry. The club head speed correlated positively with the volume of each side of the rectus abdominis and erector spinae, left quadratus lumborum, and the asymmetric ratio of the psoas major (r=0.595-0.747), but negatively with the asymmetric ratio of the quadratus lumborum (r=-0.641). Multiple regression analysis revealed that the right erector spinae volume and the asymmetric ratio of the psoas major were significant contributors for the club head speed (R2=0.797). These results indicate that the variation in the club head speed can be strongly explained by the absolute volume and bilateral asymmetry of specific trunk muscles.


Assuntos
Golfe/fisiologia , Músculo Esquelético/fisiologia , Equipamentos Esportivos , Tronco/fisiologia , Aceleração , Humanos , Masculino , Força Muscular/fisiologia , Músculo Esquelético/diagnóstico por imagem , Análise e Desempenho de Tarefas , Adulto Jovem
5.
J Sports Sci ; 38(5): 511-517, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31902294

RESUMO

This study investigated the effects of a 4-week training with hand paddles (HPD) on front-crawl swimming performance (SP), clean swimming speed (SPEED), stroke rate (SR), stroke length (SL) and tethered force (TF). Twenty swimmers (10 men and 10 women) were paired according to performance and gender, and were randomly assigned to control (CON, 22.4 ± 2.3 years) or HPD (21.8 ± 1.9 years) groups. During 4 weeks both groups performed the same training, except for a sprint training set (3 times/week, 10 × 10 strokes all-out, 1-min rest) completed with (HPD = 320 cm2) and without (CON) paddles. Afterwards, both groups performed the same training over a 2-week taper period. SP, SPEED, SR, SL and TF were assessed before (PRE) and after the 4-week period (POST), after the first (T1) and second taper weeks (T2). Swimmers rated their perceived exertion for the sprint training set (RPETS) and the training session for determining internal training load (ITL). SP, SPEED, SR, SL and TF did not change from PRE to POST, T1 and T2. ITL and RPETS were not different between groups. Training 4 weeks with HPD does not affect swimming performance, so the use of HPD remains unsupported in such period.


Assuntos
Desempenho Atlético/fisiologia , Equipamentos Esportivos , Natação/fisiologia , Feminino , Mãos , Humanos , Masculino , Fatores de Tempo , Adulto Jovem
6.
Eur J Sport Sci ; 20(1): 35-42, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31057063

RESUMO

Dynamic bike fitting often includes the optimisation of lower limb joint kinematics while participants undertake sub-maximal intensity cycling; however, this practice might not be appropriate for sprint cycling. This study aimed to determine if trained cyclists maintain lower limb angles, defined during dynamic sub-maximal bike fitting, while completing seated sprint cycling. Fifteen competitive cyclists completed two testing sessions. Dynamic bike fitting was undertaken during the first session, where handlebar positions were identified to produce pre-determined hip flexion angles (70°-110°) during sub-maximal cycling using an inertial-based motion tracking system. In the second session, full body kinematics were determined during two 6-s sprints performed at each of the pre-determined handlebar positions. During sprinting, measured right hip angles were only different at 110°, when compared with 90° (p < 0.01, d = 0.95), and 80° (p < 0.01, d = 1.49). For the left leg, measured hip angles differed between 110° vs. 90° (p < 0.01, d = 1.52), 110° vs. 80° (p < 0.01, d = 2.09), and 100° vs. 80° (p = 0.04, d = 1.06). Even though changes in bike configuration resulted in 10° increments of hip flexion during dynamic sub-maximal bike fitting, these hip angles were not replicated during sprinting. Therefore, dynamic sub-maximal bike fitting leading to changes in handlebar positions that produce hip angles of 80°-100° might not influence cycling performance due to acute changes in the body position of cyclists on the bicycle during a sprint.


Assuntos
Ciclismo/fisiologia , Extremidade Inferior/fisiologia , Postura , Equipamentos Esportivos , Adolescente , Adulto , Fenômenos Biomecânicos , Feminino , Articulação do Quadril , Humanos , Articulação do Joelho , Masculino , Amplitude de Movimento Articular , Adulto Jovem
7.
J Sci Med Sport ; 23(3): 222-236, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31690492

RESUMO

OBJECTIVES: Equestrian helmets are designed to pass certification standards based on linear drop tests onto rigid steel surfaces. However, concussions in equestrian sports occur most commonly when a rider is thrown off a horse and obliquely impacts a compliant surface such as turf or sand. This paper seeks to elucidate the mechanics of such impacts and thereby propose corresponding thresholds for the occurrence of concussion that can improve equestrian helmet standards and designs. DESIGN: The present study examined the biomechanics of real-world equestrian accidents and developed thresholds for the occurrence of concussive injury. METHODS: Twenty-five concussive and 25 non-concussive falls in equestrian sports were reconstructed using a combination of video analysis, computational and physical reconstruction methods. These represented male and female accidents from horse racing and the cross-country phase of eventing. RESULTS: The resulting thresholds for concussion [59g, 2700rad/s2, 28rad/s, 0.24 (MPS), 6.6kPa and 0.27 (CSMD10) for 50% risk] were consistent with those reported in the literature and represent a unique combination of head kinematic thresholds compared to other sports. Current equestrian helmet standards commonly use a threshold of 250g and a linear drop to a steel anvil resulting in less than 15ms impacts. This investigation found that concussive equestrian accidents occurred from oblique impacts to turf or sand with lower magnitude and longer duration impacts (<130g and >20ms). This suggests that current equestrian helmet standards may not adequately represent real-world concussive impact conditions and, consequently, there is an urgent need to assess the protective capacity of equestrian helmets under real-world conditions.


Assuntos
Traumatismos em Atletas/diagnóstico , Concussão Encefálica/diagnóstico , Dispositivos de Proteção da Cabeça/normas , Equipamentos Esportivos/normas , Aceleração , Acidentes por Quedas , Animais , Traumatismos em Atletas/prevenção & controle , Fenômenos Biomecânicos , Concussão Encefálica/prevenção & controle , Feminino , Cavalos , Humanos , Irlanda , Masculino , Esportes , Reino Unido
8.
J Strength Cond Res ; 34(1): 1-10, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31373978

RESUMO

Silva, FHO, Arantes, FJ, Gregorio, FC, Santos, FRA, Fidale, TM, Bérzin, F, Bigaton, DR, and Lizardo, FB. Comparison of the electromyographic activity of the trunk and rectus femoris muscles during traditional crunch and exercise using the 5-minute Shaper device. J Strength Cond Res 34(1): 1-10, 2020-Different training devices are available to trigger greater activation of the abdominal muscles compared with that achieved during traditional abdominal exercises. This study aimed to compare the electromyographic (EMG) activity of the upper and lower rectus abdominis, external oblique abdominis, erector spinae, and rectus femoris (RF) muscles during traditional crunch and exercise using the 5-minute Shaper device. A convenience sample of 15 healthy men (mean ± SD; age: 23.65 ± 4.49 years, body fat percentage: 14.26 ± 3.56%) was selected. All men regularly participated in physical activity. Electromyographic data were collected for 5 repetitions of each abdominal exercise (traditional crunch and exercise using the 5-minute Shaper device at beginner, intermediate, advanced, and extreme levels) in a randomized and counterbalanced manner. Data were collected using simple differential surface electrodes and analyzed using repeated-measures analysis of variance (p < 0.05). Electromyographic signals were quantified using a root-mean-square analysis and normalized using the maximum voluntary isometric contraction. Traditional crunch produced greater or similar EMG activity in the abdominal muscles and minimized RF activity compared to the 5-minute Shaper device, hence, traditional crunch is preferred for training, especially for individuals with weak abdominal musculature and lower back problems. Therefore, the use of the 5-minute Shaper device may be questioned when it is intended to intensify the activity of the abdominal muscles; however, this apparatus may be used if greater variations in training are desired, depending on individual preferences.


Assuntos
Músculos Abdominais/fisiologia , Eletromiografia , Músculo Quadríceps/fisiologia , Equipamentos Esportivos , Adulto , Dorso , Exercício Físico , Humanos , Masculino , Tronco , Adulto Jovem
9.
J Sports Sci ; 38(3): 296-303, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31783720

RESUMO

The purpose of this study was to examine the accuracy of methods to estimate ball spin rate and spin axis direction using multi-camera tracking technology. The method implemented by Hawk-Eye and a theoretical ball trajectory model were assessed for their accuracy against high speed-vision. A theoretical ball trajectory model was found to estimate ball spin rate and the spin axis direction more accurately than the method used by Hawk-Eye. The superior performance of the ball trajectory model was indicated by a lower mean bias and standard deviation (2.92 ± 222.76) than Hawk-Eye (-100.01 ± 542.44), as well as narrower limits of agreement and a 327.63 RPM lower RMSE. Spin rates less than 4500 RPM were estimated with the highest accuracy, but neither method was able to consistently and accurately estimate spin rates >4500 RPM. The application of a trajectory model to multi-camera ball tracking data provides a practical and non-invasive method to accurately estimate the spin imparted when hitting, allowing for large-scale collection of spin rates during matches.


Assuntos
Destreza Motora/fisiologia , Equipamentos Esportivos , Tênis/fisiologia , Fenômenos Biomecânicos , Interpretação Estatística de Dados , Humanos , Masculino , Rotação , Análise e Desempenho de Tarefas , Estudos de Tempo e Movimento
10.
Sports Biomech ; 19(2): 168-179, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29877754

RESUMO

The aim of this study was to investigate whether changes on foot-stretcher height were associated with characteristics of better rowing performance. Ten male rowers performed a 200 m rowing trial at their racing rate at each of three foot-stretcher heights. A single scull was equipped with an accelerometer to collect boat acceleration, an impeller with embedded magnets to collect boat speed, specially designed gate sensors to collect gate force and angle, and a compact string potentiometer to collect leg drive length. All sensor signals were sampled at 50 Hz. A one-way repeated measures ANOVA showed that raising foot-stretcher position had a significant reduction on total gate angle and leg drive length. However, a raised foot-stretcher position had a deeper negative peak of boat acceleration at the catch, a lower boat fluctuation, a faster leg drive speed, a larger gate force for the port and starboard side separately. This could be attributed to the optimisation of the magnitude and direction of the foot force with a raised foot-stretcher position. Although there was a significant negative influence of a raised foot-stretcher position on two kinematic variables, biomechanical evidence suggested that a raised foot-stretcher position could contribute to the improvement of rowing performance.


Assuntos
Desempenho Atlético/fisiologia , Pé/fisiologia , Navios/instrumentação , Equipamentos Esportivos , Esportes Aquáticos/fisiologia , Aceleração , Adulto , Fenômenos Biomecânicos , Humanos , Perna (Membro)/fisiologia , Masculino , Adulto Jovem
11.
Sports Biomech ; 19(2): 245-257, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29920153

RESUMO

Knee functional disorders are one of the most common lower extremity non-traumatic injuries reported by cyclists. Incorrect bicycle configuration may predispose cyclist to injury but the evidence of an effect of saddle setback on knee pain remains inconclusive. The aim of this study was to determine the effect of saddle setback on knee joint forces during pedalling using a musculoskeletal modelling approach. Ten cyclists were assessed under three saddle setback conditions (range of changes in saddle position ~6 cm) while pedalling at a steady power output of 200 W and cadence of 90 rpm. A cycling musculoskeletal model was developed and knee joint forces were estimated using an inverse dynamics method associated with a static optimisation procedure. Our results indicate that moving the saddle forwards was not associated with an increase of patellofemoral joint forces. On the contrary, the tibiofemoral mean and peak compression force were 14 and 15% higher in the Backward than in the Forward condition, respectively. The peak compression force was related to neither pedal force nor quadriceps muscle force but coincided with the eccentric contraction of knee flexor muscles. These findings should benefit bike fitting practitioners and coaches in the design of specific training/rehabilitation protocols.


Assuntos
Ciclismo/fisiologia , Articulação do Joelho/fisiologia , Equipamentos Esportivos , Adulto , Artralgia/fisiopatologia , Ciclismo/lesões , Fenômenos Biomecânicos , Desenho de Equipamento , Humanos , Masculino , Contração Muscular/fisiologia , Articulação Patelofemoral/fisiologia , Músculo Quadríceps/fisiologia
12.
Sports Biomech ; 19(2): 157-167, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29781789

RESUMO

External supports that reduce ankle joint mobility such as ski-boots can impair postural control of healthy participants. Although this disruptive effect has been attributed to the rigidity of the external supports, the results remained controversial and no study has been conducted in order to evaluate the influence of ski-boots rigidity. Hence, the question about the influence of ankle support rigidity on postural control remains open. This study was therefore undertaken in order to investigate the effect of ski-boots rigidity on postural control. Ten healthy active participants were recruited. The wearing of soft and rigid ski-boots was compared to barefoot while standing on a seesaw generating mediolateral and anteroposterior instability. Centre of pressure displacements were sampled with a force platform. The surface electromyographic activity of the main muscles from the leg, thigh and trunk was recorded. A motion analysis system was also used to calculate the ankle, knee and hip angles. The results did not reveal any negative influence of ski-boot rigidity on postural control but rather suggest a less active postural control with the rigid ski-boots which offered a higher mechanical contribution.


Assuntos
Equilíbrio Postural/fisiologia , Sapatos , Esqui/fisiologia , Equipamentos Esportivos , Adolescente , Tornozelo/fisiologia , Fenômenos Biomecânicos , Eletromiografia , Desenho de Equipamento , Feminino , Quadril/fisiologia , Humanos , Joelho/fisiologia , Masculino , Movimento/fisiologia , Músculo Esquelético/fisiologia , Estudos de Tempo e Movimento , Adulto Jovem
13.
J Sports Sci ; 38(4): 470-475, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31856662

RESUMO

This project examined the interrelationships between power production and upper body kinematics during a series of medicine ball push-press (MBP-P) throws. Twenty-five regular weight trainers (body mass = 86 ± 10 kg) performed a series of ballistic vertical MBP-P throws at loads representing 5% and 10% of their assessed 5RM bench press. Throws were performed lying supine on a force platform (1 kHz) with upper body kinematics assessed using standard infra-red motion capture techniques (0.5 kHz). Gross measures of performance and power production such as peak vertical ball velocity (Velpeak), peak force (Fpeak) and power (Ppeak) were recorded during the propulsive phase of the movement. Comparative analyses indicated that despite significant reductions in Velpeak from the 5% to 10% loads (P < 0.001), Fpeak remained largely unchanged (P = 0.167). Analysis of inter-trial variability showed that the gross measures of performance and power were relatively stable (Coefficient of Variation [CV%] <13%), while most upper limb segmental kinematics varied considerably between trials (CV% up to 70%). This project highlights the complexity of the relationships between power production and upper body kinematics during light load ballistic MBP-P throwing. Additionally, it shows how trained athletes can achieve similar outcomes during ballistic movements using a variety of movement strategies.


Assuntos
Força Muscular/fisiologia , Condicionamento Físico Humano/métodos , Extremidade Superior/fisiologia , Fenômenos Biomecânicos , Teste de Esforço/métodos , Humanos , Condicionamento Físico Humano/fisiologia , Equipamentos Esportivos , Estudos de Tempo e Movimento , Levantamento de Peso/fisiologia
14.
J Sci Med Sport ; 23(1): 15-19, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31501022

RESUMO

OBJECTIVES: Previous studies comparing shoes based on the amount of midsole cushioning have generally used shoes from multiple manufacturers, where factors outside of stack height may contribute to observed biomechanical differences in running mechanics between shoes. Therefore, the purpose of this study was to compare ground reaction forces and ankle kinematics during running between three shoes (maximal, traditional, and minimal) from the same manufacturer that only varied in stack height. DESIGN: Within-participant repeated measures METHODS: Twenty recreational runners ran overground in the laboratory in three shoe conditions (maximal, traditional, minimal) while three-dimensional kinematic and kinetic data were collected using a 3D motion capture system and two embedded force plates. Repeated measures ANOVAs (α=.05) compared biomechanical data between shoes. RESULTS: While the loading rate was significantly greater in the minimal shoe compared to the maximal shoe, no other differences were seen for the ground reaction force variables. Peak eversion was greater in the maximal and minimal shoe compared to the traditional shoe, while eversion duration and eversion at toe-off were greater in the maximal shoe. CONCLUSIONS: Previously cited differences in ground reaction force parameters between maximal and traditional footwear may be due to factors outside of midsole stack height. The eversion mechanics in the maximal shoes from this study may place runners at a greater risk of injury. Disagreement between previous studies indicates that more research on maximal running shoes is needed.


Assuntos
Corrida , Sapatos , Equipamentos Esportivos , Adulto , Fenômenos Biomecânicos , Desenho de Equipamento , Feminino , Humanos , Masculino , Fotografação/métodos
16.
Curr Sports Med Rep ; 18(12): 490-496, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31834181

RESUMO

Optimal bicycle configuration has been the topic of numerous studies. A majority of these have investigated the optimal saddle height and have used either static kinematics or two-dimensional kinematic measurements. Other joints, such as the hip, shoulder, and elbow joint, have not been investigated to any meaningful extent. There is, therefore, a paucity of data describing the optimal position of the upper body and pelvis in cycling. More recently, it has been recommended that bike fitting be conducted in a dynamic functional manner, as kinematics can be influenced by cycling workload. Full-body three-dimensional kinematics and saddle pressure are newer modalities available to the clinician. This review of the literature investigates the current research pertaining to the configuration of all components of the bicycle, from static methods to dynamic methods, and related to optimal performance and injury prevention. Setting the saddle height using the Holmes static method is optimal for injury prevention and performance. Guidelines for optimal bicycle configuration should take into account the training intensity when assessing kinematics as compensatory lower-limb kinematics occur during higher-power outputs. Optimal KFA using dynamic measurements should range from 33° to 43° at low intensity to 30° to 40° at high intensity when measured at the bottom dead center crank position. Saddle pressure mapping should ideally be performed at an intensity similar to what cyclists will encounter during the majority of their training and racing. Reference values and recommendations for dynamic assessments are still required for all other joints. Furthermore, intrinsic factors, such as training load and flexibility, which may affect bicycle configuration and performance, should be investigated to assess how these may influence the optimal bicycle configuration.


Assuntos
Desempenho Atlético , Ciclismo , Desenho de Equipamento , Equipamentos Esportivos , Fenômenos Biomecânicos , Humanos , Articulações/fisiologia
17.
Wilderness Environ Med ; 30(4): 407-411, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31704133

RESUMO

INTRODUCTION: BASE (buildings, antennae, span, earth) jumping involves jumping from fixed objects with a parachute. This practice is associated with fatal events. Despite considerable evolution in BASE jump practice over the past years, fatalities have increased. Identifying the main causes of fatal events and recommending processes to reduce fatalities is vital for safe BASE jumping practice. METHODS: In an effort to capture worldwide cases between 2007 and 2017, we identified and classified on a Haddon matrix each fatal event from the BASE jumping fatality list. Although not devoid of limitations, this is the most comprehensive list of BASE jumping fatal events and the main source of information on BASE-related fatalities for BASE jump participants. RESULTS: The report noted 223 fatalities, 197 of them being cliff jumps. In addition, 137 fatal jumps were wingsuit jumps. Impact and object strike were the main cause of fatal event (96%). Human factors leading to fatality were mostly low pull/no pull (64%) and bad exits (15%). Equipment factors included off-heading openings, twists, and pilot chute entanglement. Environmental factors included strong wind, poor visibility, and water. CONCLUSIONS: BASE jump practice has undergone radical transformations in the last 10 y, especially linked to the mountain environment and the use of wingsuits. These factors were linked to most fatal events. Key recommendations are basic practical measures, such as ground preparation and equipment checks, and deep technical and personal knowledge that involves regular engagement and significant introspection.


Assuntos
Traumatismos em Atletas/mortalidade , Causas de Morte , Recreação , Esportes , Feminino , Humanos , Incidência , Masculino , Fatores de Risco , Segurança , Equipamentos Esportivos
19.
Phys Ther Sport ; 40: 238-243, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31634782

RESUMO

OBJECTIVES: To quantify the effects of medicine ball mass (1 kg, 1.5 kg, 2 kg) on the intensity of 90°/90° plyometric throwing exercise. STUDY DESIGN: Controlled laboratory study. SETTING: Biomechanics laboratory. PARTICIPANTS: Fifteen physically active collegiate aged men. MAIN OUTCOME MEASURES: Kinematics of the upper extremity were collected during completion of eight to ten repetitions of 90°/90° plyometric throwing exercise with three different mass medicine balls. Four parameters, medicine ball release and contact momentum, time-to-rebound, and contact time, were computed for each selected repetition and used for statistical analysis. RESULTS: Ball mass did not significantly influence time-to-rebound (P = .718) and had a small (less than 0.05s) effect on ball contact time (P = .039). Ball release momentum was significantly greater (P < .001, 67-123% greater) than ball contact momentum. Medicine ball mass significantly increased both ball release (34-35%) and ball contact (45-67%) momentum however the effect was significantly greater for ball release momentum (P = .005). CONCLUSIONS: These results document the effects of increasing medicine ball mass during 90°/90° plyometric throwing exercise and provide evidence for designing upper extremity plyometric training programs. Based on ball contact momentum being less than ball release momentum, as well as ball mass having greater influence on ball release velocity, we suggest that 90°/90° plyometric throwing exercise is a safe exercise.


Assuntos
Exercício Pliométrico , Equipamentos Esportivos , Pesos e Medidas , Adulto , Fenômenos Biomecânicos , Humanos , Masculino , Extremidade Superior , Adulto Jovem
20.
Eur J Appl Physiol ; 119(11-12): 2579-2587, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31565754

RESUMO

PURPOSE: Previous studies have found an acute performance improvement with longer pole lengths in double poling (DP) at low-to-moderate speeds. We investigated the influence of pole lengths (PL) on O2-cost, 3D kinematics, and performance in DP at moderate-to-high speeds before (Pre) and after (Post) eight training sessions with long poles on a rollerski treadmill. METHODS: Seven male and four female skiers completed tests with two different PLs (84 and 90% of body height). Submaximal O2-cost (1º; 4.5 [females] or 6 m s-1 [males]) and a peak velocity test (1º; ∼ 7.3 m s-1) were assessed before and after a six week training period. The training sessions consisted of 50 min of low-moderate intensity training and 4 × 10 s maximal sprints with PL90%. RESULTS: On average for all tests, PL84% induced 1.0 ± 1.0% higher peak velocity compared to PL90% (mean ± CI) with no difference in vertical displacement of center of mass (COMz). From Pre to Post, peak velocity and cycle time were increased and the displacement of COMz were reduced similarly for both PLs. At moderate speed, PL90% induced less displacement of COMz with subsequent 1.1 ± 0.7% lower O2-cost compared to PL84%. From Pre to Post, the O2-cost and COMz were reduced similarly for both PLs. CONCLUSIONS: Longer PL than skiers self-selected lengths reduce O2-cost at moderate speeds, but induced lower peak velocity. Eight sessions of training with PL90% did not influence the difference between PL84% and PL90% on O2-cost, kinematics or peak velocity.


Assuntos
Desempenho Atlético/fisiologia , Consumo de Oxigênio/fisiologia , Oxigênio/metabolismo , Esqui/fisiologia , Adulto , Fenômenos Biomecânicos , Teste de Esforço/métodos , Feminino , Humanos , Masculino , Equipamentos Esportivos , Adulto Jovem
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