M Sayers

Effective attacking strategies in rugby union

Abstract Evasive change-of-direction manoeuvres (agility skills) are a fundamental ability in rugby union. In this study, we explored the attributes of agility skill execution as they relate to effective attacking strategies in rugby union. Seven Super 14 games were coded using variables that assessed team patterns and individual movement characteristics during attacking ball carries. The results indicated that tackle-breaks are a key determinant of try-scoring ability and team success in rugby union. The ability of the attacking ball carrier to receive the ball at high speed with at least two body lengths from the defence line against an isolated defender promoted tackle-breaks. Furthermore, the execution of a side-step evasive manoeuvre at a change of direction angle of 20–60° and a distance of one to two body lengths from the defence, and then straightening the running line following the initial direction change at an angle of 20–60°, was associated with tackle-breaks. This study provides critical insight regarding the attributes of agility skill execution that are associated with effective ball carries in rugby union.

Contact Skills Predicting Tackle-Breaks in Rugby Union

Contact skills are fundamental attributes of performance in rugby union. This study explored how the qualities of contact intensity and fending strategies related to tackle outcome in rugby union. Seven Super 14 games were coded using numerous quantitative and qualitative variables that assessed team patterns and individual skill execution during attacking ball carries. A variety of contact skills were shown to contribute significantly to the prediction of tackle-breaks. It was shown that 92% of tackle-breaks occurred as a result of poor defensive positioning. In addition, strong contact intensity and active fending strategies predicted 86% of poor defensive positions. Notably, active fend strategies were associated with positive phase outcomes when running straight at the defence and when using evasive methods of attack. This study provided critical insight regarding how the qualities of contact intensity and fending strategies influence effective ball carries in rugby union.

Characteristics of effective ball carries in Super 12 rugby

This study examined the determinants of effective ball carries in rugby union. Forty-eight games from the 2003 Super 12 season were analysed involving 6 teams including 90 players. Quantitative and qualitative analyses were undertaken on both individual skills and the combination of skills involved in each ball carry. Results indicated that players received the ball most often at cruising speed (41.7%) and ran the ball with moderate intensity (75.8%). The most common Running Pattern was Oblique (63.8%), while the most used Evasion Pattern was a forward step (24.7%). Pearson Chi Square (χ2) analyses showed that players who received the ball at higher speeds, ran with greater intensity, and used either Oblique Running Patterns or a forward step Evasion Pattern, were likely to be successful in the tackle and record positive phase outcomes (p <.001). Mann-Whitney U analyses showed that high ranked teams had higher reception speeds (U = 2584197.5, p =.001) and greater running intensities than low ranked teams (U = 2567508, p <.001). It was concluded that the maintenance of forward momentum, while avoiding contact through effective Running and Evasion Patterns was crucial in determining the effectiveness of ball carries.

Mechanisms of anterior cruciate ligament injuries in elite women’s netball: a systematic video analysis

ABSTRACT This study involved a systematic video analysis of 16 anterior cruciate ligament (ACL) injuries sustained by elite-level netball players during televised games in order to describe the game situation, the movement patterns involved, the player’s behaviour, and a potential injury mechanism. Eight of the ACL injuries were classified as “indirect contact” and eight as “non-contact”. Two common scenarios were identified. In Scenario A the player was jumping to receive or intercept a pass and whilst competing for the ball experienced a perturbation in the air. As a result the player’s landing was unbalanced with loading occurring predominantly on the knee of the injured side. In Scenario B the player was generally in a good position at ground contact, but then noticeably altered the alignment of the trunk before the landing was completed. This involved rotating and laterally flexing the trunk without altering the alignment of the feet. Apparent knee valgus collapse on the knee of the injured side was observed in 3/6 Scenario A cases and 5/6 Scenario B cases. Players may benefit from landing training programmes that incorporate tasks that use a ball and include decision-making components or require players to learn to cope with being unbalanced.

Rugby Union Contact Skills Alter Evasive Agility Performance during Attacking Ball Carries

Rugby union is a collision sport where evasive agility running patterns and the tackle contest determine the effectiveness of attacking ball carries. This study used three-dimensional kinematic analysis to examine the running technique of eight highly trained rugby union players during three rugby based reactive (in response to a defender positioned at the side-step) agility conditions (non-contact, contact and fend). The fend condition involved pushing a defender away with the upper body during the side-step and both fend and contact conditions required impact with an additional defender at the straighten-step, simulating a rugby tackle. Results demonstrated that a reduction in the relative height of the centre of mass relative to standing height (%CM) occurred at the straighten-step during the contact condition (47.2 ±1.9 %CM) compared to the non-contact condition (49.1 ±1.8 %CM, p <.001). The fend condition was then shown to increase %CM at the straighten-step (48.4 ±2.7 %CM) when compared to the contact condition (47.2 ±1.9 %CM, p = .017). However this difference was not observed at tackle impact during the straighten-step, with similar %CM values for fend (45.1 ±3.4 %CM) and contact conditions (44.6 ±2.6 %CM, p = .205). Further analysis showed that the number of steps displayed between the side-step and straighten-step (transition phase) altered the %CM, with one step during the transition phase increasing %CM (49.3 ±1.5 %CM) compared to two transition phase steps (46.9 ±1.6 %CM, p < .001) and no transition phase steps (46.5 ±1.6 %CM, p < .001). The changes to running technique during agility conditions involving tackle situations highlight the need for running programs in rugby union to meet the specific requirements of match-play activities.

Effect of whole-body contrast-water therapy on recovery from intense exercise of short duration

Abstract Athletes often use contrast-water therapy as a recovery modality to reduce training fatigue. However, there is debate regarding the effectiveness of this practice, particularly when active and passive recovery regimens are more readily accessible. Fourteen male state-level hockey players participated in three experimental sessions involving two 30-s maximal-intensity Wingate ergometer tests interspersed by a 12-min recovery period. Three different recovery protocols were assessed. Passive recovery involved sitting while active recovery comprised low-intensity cycling. Contrast-water therapy recovery involved three cycles of alternate immersion in heated (38°C) and cool (15°C) water for 3.5 min and 30 s respectively. Heart rate, blood lactate concentration, and ratings of fatigue were assessed immediately before (baseline) and after the first Wingate test, 3 min and 7 min into and at the end of the recovery period, and immediately after the second Wingate test. Blood pressure was assessed at baseline, immediately before recovery, and immediately after recovery. Heart rate remained elevated 3 min and 7 min into as well as after active recovery compared with both contrast-water therapy (P<0.001) and passive recovery (P<0.001), and was elevated 3 min into and after contrast-water therapy recovery compared with passive recovery (P<0.001). Blood lactate concentration was significantly lowered 7 min into and after active recovery (P<0.001) and contrast-water therapy (P<0.001) compared with passive recovery, but no significant difference was observed between active recovery and contrast-water therapy. Rating of fatigue was significantly lower for contrast-water therapy (P<0.001) compared with passive recovery and active recovery, the latter two being similar. However, no significant differences were found between the recovery modalities for any of the test or retest Wingate performance indices. Although contrast-water therapy offered similar benefits to well-established active recovery protocols, it also resulted in reduced ratings of fatigue and a faster return to baseline for some variables. Although restricted to a limited time frame, these findings reflect that the subtle effects from contrast-water therapy may translate to important practical differences that can influence the recovery choices of athletes, particularly when engaged in intense events/training where the recovery period is limited.

Tibial displacement and rotation during seated knee extension and wall squatting: A comparative study of tibiofemoral kinematics between chronic unilateral anterior cruciate ligament deficient and healthy knees

BACKGROUND Following anterior cruciate ligament (ACL) rupture, the knee becomes unstable with alterations in joint kinematics including anterior tibial displacement (ATD), and internal tibial rotation. Therapeutic exercises that promote faulty kinematics should be discouraged, especially early post-reconstruction, to avoid graft stretching and possibly longer-term osteoarthritis. Our study aimed to compare ATD and tibial rotation during two commonly prescribed exercises, namely: open kinetic chain (OKC) seated extension and closed kinetic chain (CKC) single leg wall squatting in ACL-deficient and healthy knees. METHODS Eight ACL-deficient patients and eight healthy subjects matched for age, gender and sports history were assessed using Qualisys 3D-Motion Analysis System to track 17 infrared markers while performing a seated knee extension with 3kg weight and a unilateral wall squat. We developed a model to measure joint kinematics through 70° of knee flexion and extension. ANOVA and paired t-tests compared relative ATD and tibial rotation between exercises and groups at 10° increments of flexion and extension. RESULTS We found increased ATD in the wall squat compared to the seated extension (p=0.049). There was no difference in ATD between the healthy and ACL-deficient knees but overall the tibia was significantly more internally rotated (p=0.003) in ACL-deficient knees, irrespective of the exercise, possibly interfering with the screw-home mechanism. CONCLUSIONS CKC exercises, in particular wall squats, are not necessarily safer for patients with ACL-deficiency and possibly ACL-reconstruction; although generalization should only be made with appropriate caution. Clinicians require a detailed knowledge of the effect of exercise on knee joint kinematics.

Influence of Test Distance on Change of Direction Speed Test Results

Abstract Sayers, MGL. Influence of test distance on change of direction speed test results. J Strength Cond Res 29(9): 2412–2416, 2015—This study assessed the relationships between linear running velocity and change of direction (CoD) ability and how assessing CoD ability over distances ⩽5 m influences test reliability. Participants (n = 15) from amateur rugby league teams performed 3 trials of a 20-m sprint test (light gates at 5, 10, and 20 m) and 6 trials of the 5-0-5 agility test. Twelve participants repeated the 5-0-5 test several weeks later. A three-dimensional motion capture system (250 Hz) was used to track the center of mass at 0.3, 0.5, and 1.0 m either side of the turn and identify specific CoD phase times. Pearsons correlations showed strong significant relationships between the 5-0-5 time and 5-m (r = 0.89, p < 0.001), 10-m (r = 0.91, p < 0.001), and 20-m sprint times (r = 0.93, p < 0.001). However, the strength of these relationships decreased (r < 0.65, p > 0.05) when CoD ability was measured over distances less than 0.5 m. Analysis of coefficient of variation (CV%) data indicated that the 5-0-5 test had high intratest (CV% = 2.8) and intertest reliability (CV% = 1.3), with these data decreasing for distances less than 1 m (CV% = 3.5–6.9). Specific movement phase times were the least reliable measures of CoD ability (CV% = 4.7–53.6). Results suggest a bias between high-speed linear running ability and 5-0-5 time. However, an effective compromise can be found between test reliability and the external validity by assessing CoD ability over 1 m. Findings indicate that the current practice of assessing CoD ability over large distances in questionable.

Front-crawl stroke-coordination and symmetry: A comparison between timing and net drag force protocols

Abstract This study compared stroke-coordination and symmetry using traditional timing methods and net drag force profiles. Twenty elite front-crawl swimmers Federation Internationale de Natation (FINA ranking 908 ± 59) were tested to identify the influence of both gender and breathing. A total of six randomised free-swimming trials were conducted: (i) three breathing, (ii) three non-breathing. Net drag forces were measured using an assisted towing device and the magnitude and location of minimum and maximum was determined to create a stroke symmetry index. Within the breathing condition, there were significant differences between the two symmetry index methods. Using the timing index, all 10 female participants, and seven males, illustrated symmetrical timing. For the net drag force profile, only three females and zero males exhibited a symmetrical minimum net drag force; and only four females and two males demonstrated a symmetrical maximum net drag force index. No differences existed within the non-breathing condition. There was a small (5.2%) difference in the location of maximum net drag force, when stratifying by gender. During the breathing condition, gender also influenced the percentage of overlap for the breathing stroke by 25.2%, and 14.6 % for the non-breathing stroke. A combination of the traditional timing based and net drag force based profile can guide future swimming technique intervention strategies.

Changes in drive phase lower limb kinematics during a 60 min cycling time trial

OBJECTIVES The aim of this study was to evaluate changes in the three dimensional lower limb kinematics during a simulated cycling time trial. DESIGN Repeated measures. METHODS Ten experienced male road cyclists performed a 60 min cycling test at a workload based on previous onset of blood lactate accumulation (OBLA) testing. The time trial (TT) was divided into six 10 min periods consisting of 8 min cycling at steady state (88% of OBLA) followed by a 90 s effort phase (140% of OBLA) and a 30 s recovery phase (60% of OBLA). Three-dimensional kinematic data (200 Hz) were recorded in the last minute of each steady state phase with specific attention directed at changes in range of motion (ROM) and consistency of orientation at the hip, knee and ankle joints during drive phase. RESULTS from repeated measures ANOVA indicated a mean effect for test duration on the drive phase ROM in both hip extension (p=0.027) and ankle dorsi flexion (p<0.001). The SD of the mean tibial rotation during the drive phase was the only measure of movement consistency that showed an effect for test duration (p=0.031). CONCLUSIONS These findings indicated that participants tended to increase the ROM in hip extension and ankle flexion during drive phase at the end of a TT. Changes in the consistency of tibial rotation during the drive phase may be an important indicator of fatigue and should be monitored by coaches during training due to its possible relationship with injury and fatigue.