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.

Throughout the sport-science and sports-medicine literature, the term “elite” subjects might be one of the most overused and ill-defined terms. Currently, there is no common perspective or terminology to characterize the caliber and training status of an individual or cohort. This paper presents a 6-tiered Participant Classification Framework whereby all individuals across a spectrum of exercise backgrounds and athletic abilities can be classified. The Participant Classification Framework uses training volume and performance metrics to classify a participant to one of the following: Tier 0: Sedentary; Tier 1: Recreationally Active; Tier 2: Trained/Developmental; Tier 3: Highly Trained/National Level; Tier 4: Elite/International Level; or Tier 5: World Class. We suggest the Participant Classification Framework can be used to classify participants both prospectively (as part of study participant recruitment) and retrospectively (during systematic reviews and/or meta-analyses). Discussion around how the Participant Classification Framework can be tailored toward different sports, athletes, and/or events has occurred, and sport-specific examples provided. Additional nuances such as depth of sport participation, nationality differences, and gender parity within a sport are all discussed. Finally, chronological age with reference to the junior and masters athlete, as well as the Paralympic athlete, and their inclusion within the Participant Classification Framework has also been considered. It is our intention that this framework be widely implemented to systematically classify participants in research featuring exercise, sport, performance, health, and/or fitness outcomes going forward, providing the much-needed uniformity to classification practices.

Research has often examined the relationship between 1 or 2 measures of strength and change of direction (COD) ability reporting inconsistent relationships to performance. These inconsistencies may be the result of the strength assessment used and the assumption that 1 measure of strength can represent all "types" of strength required during a COD task. Therefore the purpose of this study was to determine the relationship between several lower-body strength and power measures, COD, and agility performance. Twelve (n = 12) elite female basketball athletes completed a maximal dynamic back squat, isometric midthigh pull, eccentric and concentric only back squat, and a countermovement jump, followed by 2 COD tests (505 and T-test) and a reactive agility test. Pearson product-moment correlation and stepwise regression analysis were performed on all variables. The percentage contribution of each strength measure to an athletes total strength score was also determined. Our results demonstrated that both COD tests were significantly correlated to maximal dynamic, isometric, concentric, and eccentric strength (r = -0.79 to -0.89), with eccentric strength identified as the sole predictor of COD performance. Agility performance did not correlate with any measure of strength (r = -0.08 to -0.36), whereas lower-body power demonstrated no correlation to either agility or COD performance (r = -0.19 to -0.46). These findings demonstrate the importance of multiple strength components for COD ability, highlighting eccentric strength as a deterministic factor of COD performance. Coaches should aim to develop a well-rounded strength base in athletes; ensuring eccentric strength is developed as effectively as the often-emphasized concentric or overall dynamic strength capacity.

While studies have investigated speed and change of direction speed in rugby league players, no study has investigated the reactive agility of these athletes. In addition, the relationship among speed, change of direction speed, and reactive agility within the specific context of rugby league has not been determined. With this in mind, the purpose of this study was to investigate a wide range of speed, change of direction speed, and reactive agility tests commonly used by rugby league coaches to determine which, if any tests discriminated higher and lesser skilled players, and to investigate the relationship among speed, change of direction speed, and reactive agility in these athletes. Forty-two rugby league players completed tests of speed (5 m, 10 m, and 20 m sprint), change of direction speed ('L' run, 505 test, and modified 505 test), and reactive agility. The validity of the tests to discriminate higher and lesser skilled competitors was evaluated by testing first grade (N = 12) and second grade (N = 30) players. First grade players had faster speed, and movement and decision times on the reactive agility test than second grade players. No significant differences were detected between first and second grade players for change of direction speed. While movement times on the reactive agility test were significantly related to 10 m and 20 m sprint times and change of direction speed, no significant relationships were detected among measures of decision time and response accuracy during the reactive agility test and measures of linear speed and change of direction speed. These findings question the validity of preplanned change of direction speed tests for discriminating higher and lesser skilled rugby league players, while also highlighting the contribution of perceptual skill to agility in these athletes.

Change of direction (COD) and agility require the integration of multiple components to produce a faster performance. However, the mechanisms contributing to a faster performance without the confounding factor of athlete expertise or gender is currently unknown. Therefore, the purpose of this study was to assess body composition, strength, and kinetic profile required for a faster COD and agility performance across multiple directional changes. Six faster and 6 slower (n = 12) elite female basketball athletes completed a maximal dynamic back squat; eccentric and concentric only back squat; isometric midthigh pull; whole-body scan to determine lean, fat, and total mass; 505 COD test; T-test; and a multidirectional agility test over in-ground force plates to obtain relevant kinetic measures. Group (faster and slower) by test (2 × 3) multivariate analyses of variance with follow-up analyses of variance were conducted to examine differences between faster and slower groups and each COD and agility test (p ≤ 0.05). Faster athletes during the 505 COD test produced significantly greater vertical force (p = 0.002) and eccentric and isometric strength capacity (p = 0.001). Faster agility and T-test athletes demonstrated significantly shorter contact times (p = 0.001), greater propulsive impulse (p = 0.02), isometric strength, and relative lean mass compared with slower athletes. Differences between faster athletes across each test seem to be attributed to the mechanical demands of the directional change, increasing force and impulse application as the degree of directional change increased. These findings indicate that different mechanical properties are required to produce a faster COD and agility performances, and the importance of a greater strength capacity to enable greater mechanical adjustment through force production and body control, during different directional changes.