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Lower-Extremity Isokinetic Strength Profiling in Professional Rugby League and Rugby Union

Scott R. Brown, Matt Brughelli, Peter C. Griffiths, and John B. Cronin

Purpose:

While several studies have documented isokinetic knee strength in junior and senior rugby league players, investigations of isokinetic knee and hip strength in professional rugby union players are limited. The purpose of this study was to provide lower-extremity strength profiles and compare isokinetic knee and hip strength of professional rugby league and rugby union players.

Participants:

32 professional rugby league and 25 professional rugby union players.

Methods:

Cross-sectional analysis. Isokinetic dynamometry was used to evaluate peak torque and strength ratios of the dominant and nondominant legs during seated knee-extension/flexion and supine hip-extension/flexion actions at 60°/s.

Results:

Forwards from both codes were taller and heavier and had a higher body-mass index than the backs of each code. Rugby union forwards produced significantly (P < .05) greater peak torque during knee flexion in the dominant and nondominant legs (ES = 1.81 and 2.02) compared with rugby league forwards. Rugby league backs produced significantly greater hip-extension peak torque in the dominant and nondominant legs (ES = 0.83 and 0.77) compared with rugby union backs. There were no significant differences in hamstring-to-quadriceps ratios between code, position, or leg. Rugby union forwards and backs produced significantly greater knee-flexion-to-hip-extension ratios in the dominant and nondominant legs (ES = 1.49–2.26) than rugby union players.

Conclusions:

It seems that the joint torque profiles of players from rugby league and union codes differ, which may be attributed to the different demands of each code.

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Running Mechanics and Metabolic Responses With Water Bottles and Bottle Belt Holders

Heather K. Vincent, Laura A. Zdziarski, Kyle Fallgatter, Giorgio Negron, Cong Chen, Trevor Leavitt, MaryBeth Horodyski, Joseph G. Wasser, and Kevin R. Vincent

higher loads occurred, which can impact rates of oxygen use, energy expenditure, and injury risk while running. 11 Increasing loads (in the range of 30% of body weight in a weight vest) lengthen the stance time and magnitude of GRFs, thereby increasing the susceptibility to lower-extremity bony stress

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Improvement of Flutter-Kick Performance in Novice Surface Combat Swimmers With Increased Hip Strength

Anne Z. Beethe, Elizabeth F. Nagle, Mita Lovalekar, Takashi Nagai, Bradley C. Nindl, and Christopher Connaboy

flexion during maximal dolphin kick, reporting changes in lower-extremity kinematics and an overall decrease in swimming velocity of 0.32 m·s −1 . Bowes et al 16 examined accidental cold-water immersions investigating winter clothing or a swimsuit, finding winter clothing decreased total distance

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Is Soleus Muscle-Tendon-Unit Behavior Related to Ground-Force Application During the Sprint Start?

Erik Schrödter, Gert-Peter Brüggemann, and Steffen Willwacher

Purpose:

To describe the stretch-shortening behavior of ankle plantar-flexing muscle–tendon units (MTUs) during the push-off in a sprint start.

Methods:

Fifty-four male (100-m personal best: 9.58–12.07 s) and 34 female (100-m personal best: 11.05–14.00 s) sprinters were analyzed using an instrumented starting block and 2-dimensional high-speed video imaging. Analysis was performed separately for front and rear legs, while accounting for block obliquities and performance levels.

Results:

The results showed clear signs of a dorsiflexion in the upper ankle joint (front block 15.8° ± 7.4°, 95% CI 13.2–18.2°; rear block 8.0° ± 5.7°, 95% CI 6.4–9.7°) preceding plantar flexion. When observed in their natural block settings, the athletes’ block obliquity did not significantly affect push-off characteristics. It seems that the stretch-shortening-cycle-like motion of the soleus MTU has an enhancing influence on push-off force generation.

Conclusion:

This study provides the first systematic observation of ankle-joint stretch-shortening behavior for sprinters of a wide range of performance levels. The findings highlight the importance of reactive-type training for the improvement of starting performance. Nonetheless, future studies need to resolve the independent contributions of tendinous and muscle-fascicle structures to overall MTU performance.

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The Effect of Fatigue-Induced Changes in Eggbeater-Kick Kinematics on Performance and Risk of Injury

Nuno Oliveira, David H. Saunders, and Ross H. Sanders

Purpose:

To investigate the effects of fatigue on the vertical force and kinematics of the lower limbs during maximal water polo eggbeater kicking.

Methods:

Twelve male water polo players maintained as high a position as possible while performing the eggbeater kick with the upper limbs raised out of the water until they were unable to keep the top of the sternum (manubrium) above water. Data comprising 27 complete eggbeater-kick cycles were extracted corresponding to 9 cycles of the initial nonfatigued (0%), 50% time point (50%), and final fatigued (100%) periods of the trial. Vertical force, foot speed, and hip-, knee-, and ankle-joint angles were calculated.

Results:

Mean vertical force (0%, 212.2 N; 50%, 184.5 N; 100%, 164.3 N) progressively decreased with time. Speed of the feet (0.4 m/s), hip abduction (2.9°), and flexion (3.6°) decreased with fatigue, while hip internal rotation (3.6°) and ankle inversion (4°) increased with fatigue. Average angular velocity decreased for all joint motions.

Conclusions:

Eggbeater-kick performance decreases with fatigue. Inability to maintain foot speeds and hip and ankle actions with progressing fatigue diminishes the ability of the player to produce vertical force during the cycle. Increased internal rotation of the hip when fatigued and the large eversion/abduction of the ankle during the cycle may be predisposing factors for the prevalence of patellofemoral pain syndrome observed among eggbeater-kick performers. Appropriate training interventions that can limit the effects of fatigue on performance and injury risk should be considered.

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Measuring Muscle Activity in Sprinters Using T2-Weighted Magnetic Resonance Imaging

Takaya Yoshimoto, Yoshihiro Chiba, Hayato Ohnuma, Takuya Yanaka, and Norihide Sugisaki

finish of the sprints. Measurement of Transverse Relaxation Time (T2) The MRI was performed to obtain the T2 of the 14 lower-extremity muscles: the gluteus maximus, rectus femoris, vastus lateralis, vastus intermedius, vastus medialis, sartorius, short head of biceps femoris, long head of biceps femoris

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Biomechanical Determinants of the Reactive Strength Index During Drop Jumps

Kristof Kipp, Michael T. Kiely, Matthew D. Giordanelli, Philip J. Malloy, and Christopher F. Geiser

The Reactive Strength Index (RSI) is a measure often used to quantify dynamic lower-extremity performance during a drop jump (DJ). 1 – 3 The RSI represents a highly reliable (ie, intraclass correlation coefficient > .90) and simple index of performance that is also easy to measure and interpret. 4

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A Comparison of the Isometric Midthigh Pull and Isometric Squat: Intraday Reliability, Usefulness, and the Magnitude of Difference Between Tests

Claire J. Brady, Andrew J. Harrison, Eamonn P. Flanagan, G. Gregory Haff, and Thomas M. Comyns

dysfunction in their upper extremities. Females have shown to be weaker in the upper extremities compared with their male counterparts, 23 possibly leaving females at a disadvantage in demonstrating lower-extremity strength when performing an IMTP compared with the ISqT. In addition, participants in this

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Putting the “I” Back in Team

Patrick Ward, Aaron J. Coutts, Ricard Pruna, and Alan McCall

. Hopkins WG . A spreadsheet for monitoring an individual’s changes and trends . Sport Sci . 2017 ; 21 : 5 – 9 . 10. Kwok OM , Underhill AT , Berry JW , Luo W , Elliot TR , Yoon M . Analyzing longitudinal data with multilevel models: an example with individuals living with lower

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Associations Between Individual Lower-Limb Muscle Volumes and 100-m Sprint Time in Male Sprinters

Norihide Sugisaki, Kai Kobayashi, Hiroyasu Tsuchie, and Hiroaki Kanehisa

running and walking . Gait Posture . 2007 ; 25 ( 3 ): 380 – 384 . PubMed doi:10.1016/j.gaitpost.2006.05.002 16784858 10.1016/j.gaitpost.2006.05.002 23. Mann RA , Moran GT , Dougherty SE . Comparative electromyography of the lower extremity in jogging, running, and sprinting . Am J Sports Med