Technique and timing in women's inward two and one half somersault tuck (405C) and the men's inward two and one half somersault pike (405B) 3 m springboard dives

The purpose of this study was to compare the inward two and one half somersault dive in a tuck position (405C) performed by females (n = 22) and the inward two and one half somersault dive in a pike position (405B) performed by males (n = 24) to determine changes required by females to successfully perform 405B. Key performance variables in inward dives were also compared to those of backward dives. Video data of the dives performed at the 1999 FINA World Diving Cup were captured and digitized to obtain times and postures of the divers at specific events including takeoff and entry. Estimates of flight height and mass-normalised work done on the springboard were obtained from flight times. Some females worked the springboard strongly enough to generate sufficient height and rotation to perform 405B. Males performed 405B comfortably because they achieved better height and rotation than the females. A comparison of backward and inward dives revealed that divers are able to attain greater height in backward dives than inward dives.     

Technique and timing in the women's reverse two and one half somersault tuck (305C) and the men's reverse two and one half somersault pike (305B) 3m springboard dives

The purpose of this study was to compare the reverse two and one half somersault dive in a tuck position (305C) performed by females (n = 24), and the reverse two and one half somersault dive in a pike position (305B) performed by males (n = 21), to determine changes required by females to successfully perform 305B. Key performance variables in reverse dives were also compared to those of forward dives. Video data of the dives performed at the 1999 FINA World Diving Cup were captured and digitised to obtain times and postures of the divers at specific events including hurdle landing, takeoff, and entry. Estimates of hurdle flight height and mass-normalised work done on the springboard were obtained from hurdle and flight times. The males did more work on the springboard to achieve greater height and rotation than females. Females performing 305C had less hip and knee flexion at hurdle landing than males performing 305B and took longer to achieve maximum hip flexion after takeoff from the springboard. To progress from 305C to 305B females need to adjust their techniques to put more energy into the system. Desirable changes include increased height in the hurdle and increased hip and knee flexion prior to hurdle landing. Comparison of results for reverse dives with data previously presented for forward dives indicated that divers are more limited in the number of somersaults and dive position in reverse dives than forward dives despite equivalent or better height in reverse dives than forward dives.     

Diving

The purpose of this study was to compare the backward two and one half somersault dive in a tuck position (205C) performed by females (n = 22) and the backward two and one half somersault dive in a pike position (205B) performed by males (n = 27) and by females (n = 6) to determine changes required by females to successfully perform 205B. Video data of the dives performed at the 1999 FINA World Diving Cup were captured and digitised to obtain times and postures of the divers at specific events including maximum depression, takeoff, and entry. Estimates of mass‐normalised work done on the springboard were obtained from flight times. Males performed 31% more mass‐normalised work on the springboard to gain height than females. Based on the dive scores and the short time to extend and prepare for entry it was concluded that females are not yet able to perform 205B with the same quality as they perform 205C. Females performing backward dives need to adjust their techniques to allow increased work on the springboard to generate height and rotation. Also, faster contraction of the hip flexors may allow them to achieve the tightest position more quickly to complete rotations with more time to prepare for entry.     

Diving

The purpose of this study was to compare the reverse two and one half somersault dive in a tuck position (305C) performed by females (n = 24), and the reverse two and one half somersault dive in a pike position (305B) performed by males (n = 21), to determine changes required by females to successfully perform 305B. Key performance variables in reverse dives were also compared to those of forward dives. Video data of the dives performed at the 1999 FINA World Diving Cup were captured and digitised to obtain times and postures of the divers at specific events including hurdle landing, takeoff, and entry. Estimates of hurdle flight height and mass‐normalised work done on the springboard were obtained from hurdle and flight times. The males did more work on the springboard to achieve greater height and rotation than females. Females performing 305C had less hip and knee flexion at hurdle landing than males performing 305B and took longer to achieve maximum hip flexion after takeoff from the springboard. To progress from 305C to 305B females need to adjust their techniques to put more energy into the system. Desirable changes include increased height in the hurdle and increased hip and knee flexion prior to hurdle landing. Comparison of results for reverse dives with data previously presented for forward dives indicated that divers are more limited in the number of somersaults and dive position in reverse dives than forward dives despite equivalent or better height in reverse dives than forward dives.     

Technique and timing in women's and men's reverse one and one half somersault with two and one half twists (5335D) and men's reverse one and one half somersault with three and one half twists (5337D) 3 m springboard dives

The purpose of this study was to compare timing and technique of males and females performing reverse twisting dives in elite international competition. Video data of the dives performed at the 1999 FINA World Diving Cup were captured and digitised to obtain times and postures of the divers at specific events including takeoff and entry. Estimates of flight height and mass-normalised work done on the springboard were obtained from flight times. The data indicated that many males are able to complete an additional twist rotation because they attain more height, and therefore more time in the air, than females.     

Hip extension during the come-out of multiple forward and inward pike somersaulting dives is controlled by eccentric contraction of the hip flexors

Abstract

A modelling approach was used in the present study to investigate the role of the hip muscles during the come-out of forward and inward multiple somersaulting dives in a pike position. A planar two-segment model was used to simulate the somersault and come-out of three commonly performed dives from a 3-m springboard: forward two-and-one-half somersault pike dive (105B), forward three-and-one-half somersault pike dive (107B), and inward two-and-one-half somersault pike dive (405B). Three simulations were run for each dive: (1) hip angle was constrained to be constant, (2) hip torque was removed after 0.1 s, and (3) hip angle was constrained to a typical come-out time history used by elite divers. Simulation results indicated that hip flexion torque was required both to maintain a rigid pike position during somersault (range = 205.5–282.3 Nm) and to control the hip extension movement during the come-out (peak torque range = 355.8–548.1 Nm) in forward and inward multiple somersaulting dives. Coaches and divers should be aware that dry-land exercise drills producing hip extension movement by concentric actions of the hip extensor muscles do not replicate the neuromuscular control during the come-out of fast rotating dives.     

The validation and application of Inertial Measurement Units to springboard diving

Inertial Measurement Units (IMUs) may offer an ecologically valid, reliable, and practical method for biomechanical performance analysis. With such potential in mind, Part 1 of this study examined the accuracy of IMUs gyroscopes with an optical system (Cortex 3.3). A calibration formula standardised the IMUs angular velocity output with the optical system. The percentage differences between the two measures = 0.5% (p < 0.05), suggest IMU’s efficacy for application. In Part 2, the aim was to examine and understand how dive flight angular velocity time series plots change and increase according to dive degree of difficulty. With IMUs attached to three competitive divers performing forward somersault dives, dive flight kinematics were assessed. Biomechanically, a 4½ tuck somersault dive differed to lower degree of difficulty dives in terms of: (1) a rotational delay immediately after takeoff (to gain greater vertical translation); (2) increased total time of flight; (3) greater muscle effort to resist increased centrifugal forces produced by the increased angular velocity (1,090 °/s); and (4) greater eccentric control during deceleration allow a safe and vertical entry into the water. IMUs can be effectively utilised and integrated into contexts such as springboard diving for performance analysis and optimisation purposes.     

双杠屈体后空翻两周成挂臂的技术特征及教法

以运动生物力学对双杠屈体后空翻（超E组的高难度动作）进行研究和技术分析，总结动作的技术规律和先进的教学方法。以此指导我国优秀运动员黄旭在短时间内高标准地掌握这一动作，于国内、外比赛获得成功。     

Whole-body and multi-joint kinematic control strategy variability during backward rotating dismounts from beam

The aim of this study was to develop insight into the whole-body and multi-joint kinematic control strategy variability associated with the execution of fundamental backward rotating dismounts from beam. Two-dimensional joint centre coordinate data were obtained for ten backward piked and backward tucked somersault dismount skills performed by four female gymnasts (N = 80 trials). Gymnast-specific and group variability in whole-body and multi-joint discrete kinematic measures were compared for the aerial and impact phase of backward piked and backward tucked skills. The backward tucked skill was executed using a more variable knee joint angular velocity at take-off (mean difference in standard deviation ± SD: -2.6 ± 1.0 rad · s(-1); P < 0.01) than the backward piked skill. The variability in the whole-body and multi-joint kinematic responses produced between the impact phases of each skill was gymnast-specific. The greater variability in the localized knee joint action at take-off was considered indicative of the diverse shape element demands and key performance outcomes of the two skills. Self-selected modulations to the multi-joint kinematic strategy used in the impact phase suggested customization of the joint loading adjustments in executing the fundamental dismount skills.     

Comparative analysis of selected biomechanic characteristics between a support backward swing and support swing for the 1 1/4 straddle-piked forward salto on the parallel bars

The aim of our research was to study the relationships between performance variables in a support backward swing (SBS), which was used as a progressive step in the learning procedure for a 1 1/4 straddle-piked front somersault and the swing prior to a 1 1/4 straddle-piked front somersault from support to bent arm support on the parallel bars (5/4S). Mitja Petkovsek, parallel bars gold medallist at the 2000 EC in Bremen, performed these elements. Kinematic analysis involved CMAS software (Praha, 1993), and the Suskana body segment model that has 17 points and 15 segments. Kinetic variables were estimated using 2D IMGIM software, which has 8 points and 6 segments (Colja and Cuk, 1994). The results indicated that some kinematic aspects of the two types of swings were similar but there were important differences in kinetic aspects of the motion. During the swing for the 5/4S, force and torque were higher than in the SBS.     

Stride Adjustments during a Running Approach toward a Force Plate

Purpose

Previous research demonstrating that specific performance outcome goals can be achieved in different ways is functionally significant for springboard divers whose performance environment can vary extensively. This body of work raises questions about the traditional approach of balking (terminating the takeoff) by elite divers aiming to perform only identical, invariant movement patterns during practice.

Method

A 12-week training program (2 times per day; 6.5 hr per day) was implemented with 4 elite female springboard divers to encourage them to adapt movement patterns under variable takeoff conditions and complete intended dives, rather than balk.

Results

Intraindividual analyses revealed small increases in variability in the board-work component of each diver's pretraining and posttraining program reverse-dive takeoffs. No topological differences were observed between movement patterns of dives completed pretraining and posttraining. Differences were noted in the amount of movement variability under different training conditions (evidenced by higher normalized root mean square error indexes posttraining). An increase in the number of completed dives (from 78.91%–86.84% to 95.59%–99.29%) and a decrease in the frequency of balked takeoffs (from 13.16%–19.41% to 0.63%–4.41%) showed that the elite athletes were able to adapt their behaviors during the training program. These findings coincided with greater consistency in the divers' performance during practice as scored by qualified judges.

Conclusion

Results suggested that on completion of training, athletes were capable of successfully adapting their movement patterns under more varied takeoff conditions to achieve greater consistency and stability of performance outcomes.     

The physical demands of professional soccer goalkeepers throughout a week-long competitive microcycle and transiently throughout match-play

ABSTRACT

The physical demands of English Premier League soccer goalkeepers were quantified during training and match-play in a two-part study. Goalkeeper-specific micromechanical electrical systems (MEMS) devices, profiled training and match-day activities throughout one competitive week (n=8; part A). Changes in MEMS-derived outputs were also profiled throughout match-play (100 matches; n=8, 18±14 observations per goalkeeper; part B). In part A, goalkeeping-training elicited the most dives (51±11) versus all activities (all p≤0.030) except shooting-training (p=0.069). Small-sided games elicited the fewest (5±3) dives (all p≤0.012). High-speed distance covered in match (103±72 m) was similar to goalkeeping-training (p=0.484), while exceeding shooting-training, small-sided games, pre-match shooting, and pre-match warm-up (all p=0.012). Most changes of direction (34±12) and explosive efforts (70±18) occurred during goalkeeping-training, with values exceeding match (both p=0.012). In part B, between-half reductions in total distance, but increased high-speed changes of direction and explosive efforts, occurred (both p≤0.05). Excluding the number of high jumps, all variables differed from 0-15-min during at least one match epoch, with more dives (1.3±1.4 vs 1.0±1.1) and explosive efforts (2.5±2.4 vs 2.0±1.8) performed between 75-90-min versus 0-15-min (all p<0.05). These data highlight the differing physical demands of various activities performed by professional soccer goalkeepers throughout a competitive week.     

The effect of a resistance training programme on the grab,track and swing starts in swimming

The aim of this study was to establish the effectiveness of a resistance training programme, designed to improve vertical jumping ability, on the grab, swing and rear-weighted track starts in swimming. Twenty-three female non-competitive swimmers participated (age 19.9 +/- 2.4 years; mean +/- s). The diving techniques were practised weekly for 8 weeks. The participants were randomly assigned to a control group (n = 11) or a resistance-training group (n = 12), which trained three times a week for 9 weeks. The tests before and after the training programme involved performing each dive technique and six dry-land tests: two countermovement jumps (with and without arms), two isokinetic squats (bar speeds of 0.44 and 0.70 rad x s(-1)) and two overhead throws (with andwithout back extension). A repeated-measures multivariate analysis of variance was used to show that resistance training improved performance in the dry-land tests (P < 0.0001). No significant improvements due to training were found for any temporal, kinematic or kinetic variables within the grab or swing starts. Significant improvements (P < 0.05) were found for the track start for take-off velocity, take-off angle and horizontal impulse. The results suggest that the improved skill of vertical jumping was not transferred directly to the start, particularly in the grab technique. Non-significant trends towards improvement were observed within all starts for vertical force components, suggesting the need to practise the dives to retrain the changed neuromuscular properties.     

Non-exercise estimation of VO(2)max using the International Physical Activity Questionnaire

Non-exercise equations developed from self-reported physical activity can estimate maximal oxygen uptake (VO(2)max) as well as submaximal exercise testing. The International Physical Activity Questionnaire (IPAQ) is the most widely used and validated self-report measure of physical activity. This study aimed to develop and test a VO(2)max estimation equation derived from the IPAQ-Short Form (IPAQ-S). College-aged males and females (n = 80) completed the IPAQ-S and performed a maximal exercise test. The estimation equation was created with multivariate regression in a gender-balanced subsample of participants, equally representing five levels of fitness (n = 50) and validated in the remaining participants (n = 30). The resulting equation explained 43% of the variance in measured VO(2)max (SEE = 5.45 ml·kg(-1)·min(-1)). Estimated VO(2)max for 87% of individuals fell within acceptable limits of error observed with submaximal exercise testing (20% error). The IPAQ-S can be used to successfully estimate VO(2)max as well as submaximal exercise tests. Development of other population-specific estimation equations is warranted.     

Biomechanical differences in double poling between sexes and level of performance during a classical cross-country skiing competition

Biomechanical differences in double poling (DP) between sex and performance level were investigated in female and male cross-country skiers during a classical race (10/15 km). Skiers were divided into faster and slower on basis of race performance: females faster (n=20), females slower (n=20), males faster (n=20), and males slower (n=20). Based on video analysis while DP in a flat section of the track, joint and pole angles at pole plant (PP) and pole-off, cycle characteristics and the use and coordination pattern of heel-raise (raise of heels from the ground to have a higher body position at PP) were analysed. Faster females and males had 4.3% and 7.8% higher DP velocity than their slower counterparts (both P<0.001). Faster males had 6.5% longer cycles than slower males (P<0.001). Faster skiers stopped heel-raise later than slower skiers (females: 2.0±3.4% vs. ?1.0±3.5%, P<0.05; males: 3.9±2.4% vs. 0.8±3.2% of cycle time in relation to PP, P<0.001). At PP, faster skiers and male skiers had a smaller pole angle and greater ankle to hip and ankle to shoulder angle with respect to vertical, resulting in a more distinct forward body lean. However, the majority of the differences are likely due to higher DP velocity.     

External work and peak power are reliable measures of ergometer grinding performance when tested under load, deck heel, and grinding direction conditions

The reliability of grinding performance was assessed in 18 current Emirates Team New Zealand America's Cup sailors in two test sessions separated by 5 h using a custom-built ergometer. Sixteen different grinding conditions that varied by load (Light 39 N x m, Moderate 48 N x m, Heavy 68 N x m), deck heel (Flat 0 degrees control, Downhill 25 degrees, Uphill 25 degrees, Right 25 degrees, Left 25 degrees), and grinding direction (forwards, backwards) were assessed using peak power and external work over 5 s during maximal-effort 8-s grinds. Reliability statistics included the difference in mean (M(diff)), standard error of measurement (SEM), and intraclass correlation coefficients (ICC). External work (SEM = 1.6-6.9%; ICC = 0.91-0.99) was a more consistent performance measure than peak power (SEM = 1.3-9.6%; ICC = 0.84-0.99) across all test conditions. Testing under different load conditions resulted in external work SEMs of 1.6-3.9% with performance more reliable in lighter load conditions. Grinding performance during different heel conditions was less reliable (external work SEMs = 4.6-6.9%). Grinding direction (forward or backward) did not appear to affect performance reliability, although external work was 10-15% higher in forward grinding. Reliability is acceptable across various loads, but testing under different heel conditions may need some protocol development to allow the detection of smaller differences in performance.     

The effects of repeated maximal voluntary isokinetic eccentric exercise on recovery from muscle damage

This study investigated whether performing repeated bouts of maximal voluntary isokinetic eccentric exercise (MAX1) on 3 (MAX3) and 6 days (MAX6) after the initial bout would produce significant changes in the indirect markers of muscle damage and total work. A secondary purpose was to determine whether participants' psychological maximal effort was equivalent to the physiological maximal effort during muscle soreness. Male university students were assigned randomly to a control group (n = 12) and a group that repeated the exercise (EX; n = 12). The MAX1 was 3 x 10 repetitions of the nondominant elbow flexors on the Cybex 6000 system at a speed of 60 deg/s. The EX group performed the same exercise 3 days and 6 days after MAX1. The range of motion and maximal isometric force (MIF), muscle soreness index, plasma creatine kinase, and glutamic-oxaloacetate transaminase activities were measured before and every 24 hr for 9 days after MAX1 for both groups. MIF was also assessed once before and immediately after each MAX for the EX group. There were no significant changes (p > .05) between the groups for all criterion measures, except for total amount of work (p < .05). It is concluded that strenuous voluntary isokinetic eccentric exercise performed with damaged muscles does not appear to exacerbate damage or influence the recovery process. Although individuals could perform repeated MAXs, the total work performed was significantly reduced. This has practical implications in strength training for coaches and athletes during muscle damage.     

A comparison of men's and women's strength to body mass ratio and varus/valgus knee angle during jump landings

The purpose of this investigation was to compare valgus/varus knee angles during various jumps and lower body strength between males and females relative to body mass. Seventeen recreationally active females (age: 21.94 ± 2.59 years; height: 1.67 ± 0.05 m; mass: 64.42 ± 8.39 kg; percent body fat: 26.89 ± 6.26%; squat one-repetition maximum: 66.18 ± 19.47 kg; squat to body mass ratio: 1.03 ± 0.28) and 13 recreationally active males (age: 21.69 ± 1.65 years; height: 1.77 ± 0.07 m; mass: 72.39 ± 9.23 kg; percent body fat: 13.15 ± 5.18%; squat one-repetition maximum: 115.77 ± 30.40 kg; squat to body mass ratio: 1.59 ± 0.31) performed a one-repetition maximum in the squat and three of each of the following jumps: countermovement jump, 30 cm drop jump, 45 cm drop jump, and 60 cm drop jump. Knee angles were analysed using videography and body composition was analysed by dual-energy X-ray absorptiometry to allow for squat to body mass ratio and squat to fat free mass ratio to be calculated. Significant differences (P ≤ 0.05) were found between male and female one-repetition maximum, male and female squat to body mass ratio, and male and female squat to fat free mass ratio. Significant differences were found between male and female varus/valgus knee positions during maximum flexion of the right and left leg in the countermovement jump, drop jump from 30 cm, drop jump from 45 cm, and drop jump from 60 cm. Correlations between varus/valgus knee angles and squat to body mass ratio for all jumps displayed moderate, non-significant relationships (countermovement jump: r = 0.445; drop jump from 30 cm: r = 0.448; drop jump from 45 cm: r = 0.449; drop jump from 60 cm: r = 0.439). In conclusion, males and females have significantly different lower body strength and varus/valgus knee position when landing from jumps.     

Techniques used in high-scoring and low-scoring 'Roche' vaults performed by elite male gymnasts

The 16 highest-scored Roche vaults (G1) performed during the 2000 Olympic Games were compared with those receiving the 16 lowest-scores (G2). A 16-mm motion picture camera operating at 100 Hz recorded the vaults during the competition. The results of t tests (p < .05) indicated G1, compared to G2, had (a) shorter time of board support, greater normalised average upward vertical force and backward horizontal force exerted by the board, greater change in the vertical velocity while on the board, and greater vertical velocity at board take-off, (b) comparable linear and angular motions in pre-flight, (c) smaller backward horizontal impulse exerted by the horse, smaller loss of the horizontal velocity while on the horse, and greater horizontal and vertical velocities at horse take-off, (d) greater height and larger horizontal distance of post-flight, (e) higher body mass centre at knee release, and (f) higher mass centre, greater normalised moment of inertia, and smaller vertical velocity at mat touchdown. Therefore, gymnasts and coaches should focus on sprinting the approach; blocking and pushing-off the take-off board rapidly and vigorously; departing the board with a large vertical velocity; exerting large downward vertical force and small forward horizontal force from the hand-stand position while on the horse; departing the horse with large horizontal and vertical velocities; and completing the majority of the double salto forward near the peak of trajectory and releasing the knees above the top of the horse to prepare for a controlled landing.     

A lateral ankle sprain during a lateral backward step in badminton: A case report of a televised injury incident

BackgroundThis study presents a kinematic analysis of an acute lateral ankle sprain incurred during a televised badminton match. The kinematics of this injury were compared to those of 19 previously reported cases in the published literature.MethodsFour camera views of an acute lateral ankle sprain incurred during a televised badminton match were synchronized and rendered in 3-dimensional animation software. A badminton court with known dimensions was built in a virtual environment, and a skeletal model scaled to the injured athlete's height was used for skeletal matching. The ankle joint angle and angular velocity profiles of this acute injury were compared to the summarized findings from 19 previously reported cases in the published literature.ResultsAt foot strike, the ankle joint was 2° everted, 33° plantarflexed, and 18° internally rotated. Maximum inversion of 114° and internal rotation of 69° was achieved at 0.24 s and 0.20 s after foot strike, respectively. After the foot strike, the ankle joint moved from an initial position of plantarflexion to dorsiflexion—from 33° plantarflexion to 53° dorsiflexion (range = 86°). Maximum inversion, dorsiflexion, and internal rotation angular velocity were 1262°/s, 961°/s, and 677°/s, respectively, at 0.12 s after foot strike.ConclusionA forefoot landing posture with a plantarflexed and internally rotated ankle joint configuration could incite an acute lateral ankle sprain injury in badminton. Prevention of lateral ankle sprains in badminton should focus on the control and stability of the ankle joint angle during forefoot landings, especially when the athletes perform a combined lateral and backward step.