Exercise Physiology: Energy, Nutrition and Human Performance

The two Yo-Yo intermittent recovery (IR) tests evaluate an individual's ability to repeatedly perform intense exercise. The Yo-Yo IR level 1 (Yo-Yo IR1) test focuses on the capacity to carry out intermittent exercise leading to a maximal activation of the aerobic system, whereas Yo-Yo IR level 2 (Yo-Yo IR2) determines an individual's ability to recover from repeated exercise with a high contribution from the anaerobic system. Evaluations of elite athletes in various sports involving intermittent exercise showed that the higher the level of competition the better an athlete performs in the Yo-Yo IR tests. Performance in the Yo-Yo IR tests for young athletes increases with rising age. The Yo-Yo IR tests have shown to be a more sensitive measure of changes in performance than maximum oxygen uptake. The Yo-Yo IR tests provide a simple and valid way to obtain important information of an individual's capacity to perform repeated intense exercise and to examine changes in performance.

https://www.fedecoltenis.com/userfiles/Capacitacion/2013/YOYO%20RECOVERY%20TEST.pdf

The Yo-Yo intermittent recovery test : a useful tool for evaluation of physical performance in intermittent sports.

At present, no agreement on a precise definition of agility within the sports science community exists. The term is applied to a broad range of sport contexts, but with such great inconsistency, it further complicates our understanding of what trainable components may enhance agility. A new definition of agility is proposed: "a rapid whole-body movement with change of velocity or direction in response to a stimulus". Agility has relationships with trainable physical qualities such as strength, power and technique, as well as cognitive components such as visual-scanning techniques, visual-scanning speed and anticipation. Agility testing is generally confined to tests of physical components such as change of direction speed, or cognitive components such as anticipation and pattern recognition. New tests of agility that combine physical and cognitive measures are encouraged.

/pdf/agility-literature-review-classifications-training-and-21h3p91kzr.pdf

Agility literature review: Classifications, training and testing

Background: A high level of strength is inherent in elite soccer play, but the relation between maximal strength and sprint and jumping performance has not been studied thoroughly. Objective: To determine whether maximal strength correlates with sprint and vertical jump height in elite male soccer players. Methods: Seventeen international male soccer players (mean (SD) age 25.8 (2.9) years, height 177.3 (4.1) cm, weight 76.5 (7.6) kg, and maximal oxygen uptake 65.7 (4.3) ml/kg/min) were tested for maximal strength in half squats and sprinting ability (0–30 m and 10 m shuttle run sprint) and vertical jumping height. Result: There was a strong correlation between maximal strength in half squats and sprint performance and jumping height. Conclusions: Maximal strength in half squats determines sprint performance and jumping height in high level soccer players. High squat strength did not imply reduced maximal oxygen consumption. Elite soccer players should focus on maximal strength training, with emphasis on maximal mobilisation of concentric movements, which may improve their sprinting and jumping performance.

https://bjsm.bmj.com/content/bjsports/38/3/285.full.pdf

Strong correlation of maximal squat strength with sprint performance and vertical jump height in elite soccer players

The primary aim of this study was to determine reliability and factorial validity of squat (SJ) and countermovement jump (CMJ) tests. The secondary aim was to compare 3 popular methods for the estimation of vertical jumping height. Physical education students (n = 93) performed 7 explosive power tests: 5 different vertical jumps (Sargent jump, Abalakow's jump with arm swing and without arm swing, SJ, and CMJ) and 2 horizontal jumps (standing long jump and standing triple jump). The greatest reliability among all jumping tests (Cronbach's alpha = 0.97 and 0.98) had SJ and CMJ. The reliability alpha coefficients for other jumps were also high and varied between 0.93 and 0.96. Within-subject variation (CV) in jumping tests ranged between 2.4 and 4.6%, the values being lowest in both horizontal jumps and CMJ. Factor analysis resulted in the extraction of only 1 significant principal component, which explained 66.43% of the variance of all 7 jumping tests. Since all jumping tests had high correlation coefficients with the principal component (r = 0.76-0.87), it was interpreted as the explosive power factor. The CMJ test showed the highest relationship with the explosive power factor (r = 0.87), that is, the greatest factorial validity. Other jumping tests had lower but relatively homogeneous correlation with the explosive power factor extracted. Based on the results of this study, it can be concluded that CMJ and SJ, measured by means of contact mat and digital timer, are the most reliable and valid field tests for the estimation of explosive power of the lower limbs in physically active men.

Reliability and factorial validity of squat and countermovement jump tests.

Background. The purpose of this study was to identify the relationships between leg muscle power and sprinting speed with changes of direction. Methods. Experimental design: the study was designed to describe relationships between physical qualities and a component of sports performance. Setting: testing was conducted in an indoor sports hall and a biomechanics laboratory. Participants: 15 male participants were required to be free of injury and have recent experience competing in sports involving sprints with changes of direction. Measures: subjects were timed in 8 m sprints in a straight line and with various changes of direction. They were also tested for bilateral and unilateral leg extensor muscle concentric power output by an isokinetic squat and reactive strength by a drop jump. Results. The correlations between concentric power and straight sprinting speed were non-significant whereas the relationships between reactive strength and straight speed were statistically significant. Correlations between muscle power and speed while changing direction were generally low and non-significant for concentric leg power with some moderate and significant (p<0.05) coefficients found for reactive strength. The participants who turned faster to one side tended to have a reactive strength dominance in the leg responsible for the push-off action. Conclusions. The relationships between leg muscle power and change-of-direction speed were not consistent. Reactive strength as measured by the drop jump appears to have some importance for lateral change-of-direction speed, possibly because of similar push-off actions. It was concluded that reactive strength of the leg extensor muscles has some importance in change-of-direction performance but the other technical and perceptual factors than influence agility performance should also be considered.

Is muscle power related to running speed with changes of direction

Static stretching (SS) is used pervasively throughout the exercise science and sporting communities as a fundamental element of the pre-exercise warm-up procedure. While SS has been proven effective to increase range of motion (ROM), its proposed benefits are questionable and relatively unsubstantiated. Moreover, in recent years researchers have demonstrated that pre-exercise SS may in fact be detrimental to subsequent performance due to impaired force and power output. Yet the practical application of these relatively recent findings is limited due to the prolonged SS protocols utilized. In addition, timelines associated with enhanced ROM and performance decrements have not been established. Thus, the objectives of this study were to determine if a typical SS routine decreased force, activation, and power while improving ROM. Secondly, the study attempted to compare the duration of the performance decrement to the duration of the augmented ROM.

/pdf/an-acute-bout-of-static-stretching-effects-on-force-and-17bwvfbdkf.pdf

An acute bout of static stretching: effects on force and jumping performance.

The purpose of this study was to investigate the relationship between strength measures and sprinting performance, and to determine if these relationships varied for different phases of sprint running. Twenty (11 males and 9 females) elite junior track and field athletes served as subjects. Athletes performed maximum sprints to 50 m from a block start and time to 2.5, 5, 10, 20, 30, 40 and 50 m were recorded by electronic timing gates. The resultant forces applied to the blocks were obtained from two force platforms. Twenty-seven measures of strength and speed-strength (absolute and relative to bodyweight) were collected from the height jumped and the force-time curve recorded from the takeoff phase of vertical jumping movements utilizing pure concentric, stretch shortening cycle (SSC) and isometric muscular contractions. Pearson correlation analysis revealed that the single best predictor of starting performance (2.5 m time) was the peak force (relative to bodyweight) generated during a jump from a 120 degree knee angle (concentric contraction) (r = 0.86, p = 0.0001). The single best correlate of maximum sprinting speed was the force applied at 100 ms (relative to bodyweight) from the start of a loaded jumping action (concentric contraction) (r = 0.80, p = 0.0001). SSC measures and maximum absolute strength were more related to maximum sprinting speed than starting ability. It was concluded that strength qualities were related to sprinting performance and these relationships differed for starting and maximum speed sprinting.

Relationship between strength qualities and sprinting performance

The purpose of this research was to determine whether a loaded countermovement jump (LCMJ) could be enhanced if preceded by a set of half-squats with a 5-RM load. Ten subjects experienced with the squat exercise performed 2 sets of 5 LCMJ, 1 set of 5 squat reps with a 5-RM load, and 1 set of

Warren B. Young

Papers

Agility literature review: Classifications, training and testing

Is muscle power related to running speed with changes of direction

An acute bout of static stretching: effects on force and jumping performance.

Relationship between strength qualities and sprinting performance

Acute Enhancement of Power Performance From Heavy Load Squats