Optimal Performance Benefits Research Articles

What Should We Do About Habitual Caffeine Use in Athletes?

Caffeine is a well-established ergogenic aid, demonstrated to enhance performance across a wide range of capacities through a variety of mechanisms. As such, it is frequently used by both athletes and non-athletes alike. As a result, caffeine ingestion is ubiquitous in modern society, with athletes typically being exposed to regular non-supplemental caffeine through a variety of sources. Previously, it has been suggested that regular caffeine use may lead to habituation and subsequently a reduction in the expected ergogenic effects, thereby blunting caffeine’s performance-enhancing impact during critical training and performance events. In order to mitigate this expected performance loss, some practitioners recommended a pre-competition withdrawal period to restore the optimal performance benefits of caffeine supplementation. However, at present the evidence base exploring both caffeine habituation and withdrawal strategies in athletes is surprisingly small. Accordingly, despite the prevalence of caffeine use within athletic populations, formulating evidence-led guidelines is difficult. Here, we review the available research regarding habitual caffeine use in athletes and seek to derive rational interpretations of what is currently known—and what else we need to know—regarding habitual caffeine use in athletes, and how athletes and performance staff may pragmatically approach these important, complex, and yet under-explored phenomena.

Challenges and progress toward efficient gradual typing (invited talk)

Mixing static and dynamic type checking in the same language is catching on, with the TypeScript and Flow variants of JavaScript, the MyPy and Reticulated variants of Python, the Strongtalk and Gradualtalk variants of Smalltalk, as well as Typed Racket, Typed Clojure, and Perl 6. The gradual typing approach to such mixing seeks to protect the statically typed code from the dynamically typed code, allowing compilers to leverage type information when optimizing the static code. Unfortunately, ensuring soundness requires runtime checking at the boundaries of typed and untyped code, and the cost of this checking can drown out the performance benefits of optimization. For example, in Typed Racket, some partially typed programs are 1000X slower than the untyped or fully typed version of the same program. But all is not lost! In this talk I present the results of ongoing research to tame the runtime overheads of gradual typing in the context of a prototype compiler, named Grift, that we are developing at Indiana University.

Cricket pace bowling: The trade-off between optimising knee angle for performance advantages v. injury prevention

Background. The cricket pace bowler utilises various strategies, including a more extended front knee angle, to achieve optimal performance benefits. At times this is done to the detriment of injury prevention.Objective. To investigate the relationship between three-dimensional (3D) knee kinematics during pace bowling action, injury incidence and bowling performance at the start and end of a cricket season.Methods. Knee angle and ball release (BR) speed of injury-free premier league (club level) cricket pace bowlers over the age of 18 years were measured at the start and end of the cricket season. Kinematic, injury- and bowling performance-related (BR speed and accuracy) data were analysed using paired and independent Student's t-tests, Pearson's correlation coefficient,χ2 test and a two-way analysis of covariance with repeated measures.Results. Thirty-one bowlers participated in this study, and kinematic data of a subset of 17 were analysed. Nine bowlers (53%) sustained injuries during the cricket season. No statistically significant relationship was found between knee angle and injury. Bowlers who did not sustain an injury bowled with more knee flexion at the start of the season (mean (standard deviation) 157.07° (12.02°)) than at the end of it (163.95° (6.97°)) (p=0.01). There was no interaction between accuracy and knee angle. There was a good to excellent inverse correlation between BR speed and knee angle among bowlers who remained injury free (r=.0.79; p=0.18).Conclusion. Bowlers who remain injury free during the course of the season may use strategies other than the front knee angle to facilitate high BR speeds. Technique-related variables which are more 'protective' against injuries while allowing for higher BR speeds should be further investigated among bowlers.

The moderating role of contextual factors on quality management practices

This study investigates how contextual factors influence the relationship between Quality Management (QM) practices and manufacturing performance. It contributes to the contingency theory of QM effectiveness. Drawing on the management literature, we differentiate two different groups of QM practices: Quality Exploitation and Quality Exploration. The analysis empirically investigates the internal fit with organizational structure and the external fit with environmental uncertainty on the relationship between Quality Exploration, Quality Exploitation, and operational performance. The data comes from a survey of 238 manufacturing plants in three industries across eight countries. Regression analyses show that both internal fit with the organizational structure and external fit with the environment affect performance. The findings also provide insights for managers on how to customize QM programs to achieve optimal performance benefits. In stable environments Quality Exploitation practices provide the best performance outcomes, while in a dynamic environment Quality Exploration practices with an organic organizational structure give the best results.

Postactivation Potentiation in Professional Rugby Players: Optimal Recovery

Following a bout of high-intensity exercise of short duration (preload stimulus), the muscle is in both a fatigued and a potentiated (referred to as postactivation potentiation) state. Consequently, subsequent muscle performance depends on the balance between these 2 factors. To date, there is no uniform agreement about the optimal recovery required between the preload stimulus and subsequent muscle performance to gain optimal performance benefits. The aim of the present study was to determine the optimal recovery time required to observe enhanced muscle performance following the preload stimulus. Twenty-three professional rugby players (13 senior international players) performed 7 countermovement jumps (CMJs) and 7 ballistic bench throws at the following time points after a preload stimulus (3 repetition maximum [3RM]): baseline, approximately 15 seconds, and 4, 8, 12, 16, and 20 minutes. Their peak power output (PPO) was determined at each time point. Statistical analyses revealed a significant decrease in PPO for both the upper (856 +/- 121 W vs. 816 +/- 121 W, p < 0.001) and the lower (4,568 +/- 509 W vs. 4,430 +/- 495 W, p = 0.005) body when the explosive activity was performed approximately 15 seconds after the preload stimulus. However, when 12 minutes was allowed between the preload stimulus and the CMJ and ballistic bench throws, PPO was increased by 8.0 +/- 8.0% and 5.3 +/- 4.5%, respectively. Based on the above results, we conclude that muscle performance (e.g., power) can be significantly enhanced following a bout of heavy exercise (preload stimulus) in both the upper and the lower body, provided that adequate recovery (8-12 minutes) is given between the preload stimulus and the explosive activity.

Organizing forms in change management: The role of structures, processes and boundaries in a longitudinal case analysis

This paper examines change management at William Angliss Institute of Technical and Further Education (TAFE) against the three organizational dimensions of structures, processes and boundaries identified by the INNFORM Study. Its experience confirms that even when an organization adopts a systemic approach and implements change across each design dimension, optimal performance benefits depend on mutually reinforcing and complementary changes. Furthermore, improvement to processes, particularly communications and human resources practices, plays a pivotal role, as complementary change across all dimensions depends ultimately on the contribution and commitment of organization members. Case findings also highlight the need for ambidextrous forms of organizing that combine ‘controllability’ with ‘responsiveness’. The conceptual notion of organizing dualities has been employed to provide a practical interpretation of the ostensibly competing imperatives implied by ambidexterity. This case explores the dualities that can be demonstrated for the INNFORM triumvirate of structures, processes and boundaries. The dualities interpretation emphasizes an acceptance of texture and the simultaneous presence of what are conventionally viewed as incompatible organizing forms. This was considered a useful conceptual vehicle in the analysis of a case study covering nearly ten years of serious change interventions, where one theoretical view can be misleading in understanding the subtleties and complexities of the actual changes that occurred.