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Hermann Zbinden-Foncea, Isabel Rada, Jesus Gomez, Marco Kokaly, Trent Stellingwerff, Louise Deldicque and Luis Peñailillo

significant jump-performance improvements in elite female players. 18 To test jump ability, the countermovement jump (CMJ) is commonly used since it replicates jumps performed during a real game. Furthermore, the CMJ has been shown to be one of the best tests to detect neuromuscular fatigue due to its high

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Sahar Boozari, Mohammad Ali Sanjari, Ali Amiri and Ismail Ebrahimi Takamjani

, proprioception, power, and pain. 2 , 3 , 5 , 6 Some have suggested that the effects of KT would be more beneficial if they also existed in functional situations, high-load tasks, or fatiguing circumstances. 5 – 7 A popular use of KT is in sports activities, such as countermovement jump (CMJ). 5 , 6 , 8 – 11

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Jeffrey D. Simpson, Ludmila Cosio-Lima, Eric M. Scudamore, Eric K. O’Neal, Ethan M. Stewart, Brandon L. Miller, Harish Chander and Adam C. Knight

Wearing a weighted vest (WV) during daily living activities and training (WVDT), 1 – 3 or during daily living only, 4 – 6 is one form of external loading used to enhance countermovement jump (CMJ) and sprinting performance. The theoretical benefits of WVDT were supported in a seminal

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Malachy P. McHugh, Tom Clifford, Will Abbott, Susan Y. Kwiecien, Ian J. Kremenic, Joseph J. DeVita and Glyn Howatson

Countermovement jump (CMJ) tests are commonly used to assess recovery of muscle function following strenuous exercise. Impairments in CMJ have been demonstrated on the days following various forms of exercise including drop jump protocols, 1 – 3 repeated sprint, and simulated field sport tests 4

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Adam Grainger, Paul Comfort and Shane Heffernan

Purpose:

Partial body cryotherapy (PBC) has been shown to be beneficial for post-exercise recovery, however, no study has demonstrated the effectiveness of PBC as a recovery modality following elite rugby union (RU) training. RU is a unique sport that involves high velocity collisions with minimal protective wear and may represent a situation that could induce greater performance decrements than other sports, thus PBC could be beneficial. The application of PBC in ‘real-world’, as opposed to the laboratory setting, has rarely been investigated during the competitive phase of a playing season and warranted investigation.

Methods:

In a counterbalanced sequential research design, professional rugby athletes (n = 18, age, 25.4 ± 4.0 years; training age, 7.2 ± 4.0 years; mass, 99.8 ± 10.6 kg and height 188.3 ± 6.0 cm) were assigned to a 12-week PBC intervention, washout period (4 weeks) and reassessed as their own controls. Total self-reported well-being, muscle soreness, sleep quality and countermovement jump (CMJ) height were assessed pre and 40 hours post ‘real world’ training (field and gym). Wilcoxon signed rank tests and Cohen’s d were used for statistical analysis.

Results:

No differences were observed in the PBC or control conditions (p > 0.05; d 0.00-0.14) for well-being (-0.02 ± 0.08% vs. 0.01 ± 0.06%), muscle soreness (-0.01 ± 0.11% vs. 0.01 ± 0.16%), sleep quality (-0.03 ± 0.14% vs 0.10 ± 0.29%) or CMJ height (36.48 to 36.59 vs 38.13 to 37.52 cm; p = 0.54).

Conclusions:

These results suggest that the administration of PBC is ineffective at enabling the restoration of selected performance parameters during the performance maintenance phase of the competitive season. To ascertain the appropriation of its use, future investigations should seek to assess the use of cryotherapies at various phases of the elite rugby union competitive season.

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Kym J. Williams, Dale W. Chapman, Elissa J. Phillips and Nick Ball

quasi-linear force–velocity relationship is reported, 4 with empirical evidence supporting a load equal to body mass as the optimal load to maximize system power during a countermovement jump (CMJ). 5 – 7 Long-term specialized training can have a profound influence on a muscle’s contractile profile, 8

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Adam Grainger, Paul Comfort and Shane Heffernan

activities. 2 , 3 Evidence to support delayed restoration after “rugby match play” is well documented. 3 , 4 McLellan et al 4 assessed markers of postmatch fatigue in elite rugby league, showing that countermovement jump (CMJ) peak power was reduced for up to 48 hours and that creatine kinase and cortisol

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Joel M. Garrett, Stuart R. Graham, Roger G. Eston, Darren J. Burgess, Lachlan J. Garrett, John Jakeman and Kevin Norton

after games and training. 1 , 5 For the monitoring of neuromuscular fatigue (NMF) within high-performance team sports environments, the countermovement jump (CMJ) test is recognized as the reference standard test. 6 , 7 It has been shown to possess both robust reliability and validity 1 , 6 , 8 , 9

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Rob Gathercole, Ben Sporer, Trent Stellingwerff and Gord Sleivert

Purpose:

To examine the reliability and magnitude of change after fatiguing exercise in the countermovement-jump (CMJ) test and determine its suitability for the assessment of fatigue-induced changes in neuromuscular (NM) function. A secondary aim was to examine the usefulness of a set of alternative CMJ variables (CMJ-ALT) related to CMJ mechanics.

Methods:

Eleven male college-level team-sport athletes performed 6 CMJ trials on 6 occasions. A total of 22 variables, 16 typical (CMJ-TYP) and 6 CMJ-ALT, were examined. CMJ reproducibility (coefficient of variation; CV) was examined on participants’ first 3 visits. The next 3 visits (at 0, 24, and 72 h postexercise) followed a fatiguing high-intensity intermittent-exercise running protocol. Meaningful differences in CMJ performance were examined through effect sizes (ES) and comparisons to interday CV.

Results:

Most CMJ variables exhibited intraday (n = 20) and interday (n = 21) CVs of <10%. ESs ranging from trivial to moderate were observed in 18 variables at 0 h (immediately postfatigue). Mean power, peak velocity, flight time, force at zero velocity, and area under the force–velocity trace showed changes greater than the CV in most individuals. At 24 h, most variables displayed trends toward a return to baseline. At 72 h, small increases were observed in time-related CMJ variables, with mean changes also greater than the CV.

Conclusions:

The CMJ test appears a suitable athlete-monitoring method for NM-fatigue detection. However, the current approach (ie, CMJ-TYP) may overlook a number of key fatigue-related changes, and so practitioners are advised to also adopt variables that reflect the NM strategy used.

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Mostafa Afifi and Richard N. Hinrichs

It is common practice to study jump landing mechanics by having subjects step off a box set at a certain height instead of landing from a jump. This practice assumes that the landing mechanics are similar between stepping off a box and a countermovement jump as long as the heights can be matched. The mechanics of the two methods had never been compared when landing from identical heights. Thus, the purpose of this study was to compare the mechanics of landing from a countermovement jump to landing from a step-off. Participants performed three maximal countermovement jumps. The mechanics of one countermovement jump was compared with a center of mass fall height matched step-off landing. The step-off landing showed a more rapid time to peak ground reaction force (GRF) in both genders and greater GRF peak and loading rate in males only. No difference was observed between joint angles at initial contact; however, the countermovement jump showed significantly greater joint flexion angles at peak GRF for both genders. EMG showed greater muscle activity during the countermovement jump condition in all subjects. It was concluded that countermovement jump landings are different from step-off landings; thus, results from analyses involving step-off landings should be taken with caution if the aim is to relate them to landing from a jump.