Journal Publications

ABSTRACT

Objectives: The aim of this study was to examine the influence of a 10 min lower-body self-myofascial release (SMFR) protocol on countermovement jump (CMJ) performance and CMJ forcetime variables in pre-elite Rugby Union players, and to assess if differences exist between groups; forwards vs. backs. Design: Pre-elite male Rugby Union academy players (n=20) volunteered for the study and were categorized as forwards (FWD) or backs (BK). Testing occurred in a sequenced mixed design involving TEST (repeated; Control vs. SMFR) and GROUP (FWDvs. BK). Methods: Irrespective of player position, all subjects completed baseline assessments consisting of dynamic warm-up (DYN) and 6 CMJs, followed by 20 min complete rest, then 10 min lower-body SMFR protocol, and subsequent DYN and CMJ re-test. Participants performed the SMFR exercises to 9 various sites over the lower extremities on both sides of the body. The data from the best 3 jumps relative to jump height were averaged and used for analysis. Results: The SMFR had no significant effect on CMJ height for GROUP (p=0.139). Significant differences in concentric force were found for GROUP (p=0.004) and TEST (p=0.04). For eccentric rate of force development (RFD) there was a significant effect for TEST (p=0.008). For concentric impulse there was a significant difference for GROUP (p=0.016). Conclusion: The SMFR protocol combined with DYN affected CMJ force-time variables positively without deteriorating jump height in pre-elite academy Rugby Union players. Strength and conditioning coaches can prescribe SMFR with DYN prior to training and competition in Rugby Union to enhance force production capabilities in dynamic multi-joint movements without negatively affecting an individual performance

ABSTRACT

Muscle contractile properties have previously been distinguished by fiber typing muscle samples obtained from needle biopsy; however due to conflicting evidence regarding sampling bias and the related need for multiple biopsies, it is not certain if these results are a reliable reflection of whole muscle fiber type expression. Inter-correlations between laboratory and field-based measures of muscle contractile power were used to determine which assessments best discriminate between participants of varying sprint performance, and indirectly reveal potential for power vs. endurance exercise performance. Healthy active male (n=32) and female (n=17) participants were recruited from the Central West region of New South Wales. Isometric rate of force development (RFD) and isokinetic torque were assessed at different velocities. A counter movement jump (CMJ) test was implemented to assess concentric and eccentric RFD. A modified Wingate test was used to assess peak power expressed as Watts using a stationary start to the onset of decreased cadence. A 20m sprint was used as a field-based measurement of exercise performance, recording split times at 2m, 10m and 20m, and interval times from 2-10m, 2-20m, and 10-20m. Over 85% (r2=0.851) of 10-20m sprint running performance variance was significantly accounted for by a multiple regression model consisting of peak Watts per kilogram body mass during the modified Wingate (pkWkg), sex, and peak concentric rate of force development (pkcRFDkg). Results indicate a highly significant and predictive relationship between performance measures assessed by the modified Wingate test and sprint running performance in both males and females. Laboratory power tests alone seem sensitive enough to ascertain suitability for power vs. endurance performance potential.

ABSTRACT

The increased training demands placed on elite athletes are well established. As such, monitoring recovery as a means of managing and decreasing the risk of non-functional overreaching and overtraining is common, the importance of monitoring sleep variables is still widely overlooked. Adequate sleep quality and quantity is essential for the necessary psychological and physiological recovery from cumulative training stimuli. However little is known regarding the objective sleep characteristics of elite athletes. While several methods are currently available to monitoring both subjective and objective sleep variables, many are considered somewhat invasive, expensive, and labour intrusive, and hence not practical to be implemented in an elite sport environment. A PubMed search including the following keywords in different combinations: ‘sleep’, ‘sleep loss’, ‘sleep deprivation’, ‘sleep extension’, ‘recovery’, ‘fatigue’, ‘training’, ‘stress’, ‘travel’, ‘nap’, and ‘smartphones’ was used, with all titles and abstracts carefully read and relevant articles retrieved for review. This review outlines the effects of acute and chronic sleep deprivation on physical, cognitive and performance outcomes; and presents newly developed Smartphone applications for monitoring sleep variables which can be effectively implemented in an elite sport environment. The role of sleep in recovery is a complex phenomenon, however in a practical sense; monitoring sleep through the use of Smartphone technology may allow various sleep variables to be monitored accurately and easily. Such data may assist to identify athletes that require sleep hygiene education, and this may assist recovery and enhance performance. Therefore, Smartphone technology could assist athletes in achieving a ‘competitive edge’ through improving one of the most efficacious recovery strategies available, that of sleep.

ABSTRACT

Introduction: Understanding the specific physiology of females of different ages and fitness status during exercise will improve exercise prescription for females for sport, and also in the prevention and rehabilitation of chronic disease. Previously, we have documented a significant gender influence in a multiple regression model of determinants to short distance sprint performance. The purpose of this research was to further explore the male vs. female differences in laboratory measures of muscular power to improve our understanding of specific physiological differences between males and females during intense exercise. Methods: 49 healthy active males (n = 32) and females (n = 17) participants performed four assessments of muscle contractile function in random order, with 15 min of rest between each task. Testing consisted of (1) the isometric rate of force development (RFD); (2) isokinetic torque at different velocities; (3) a counter movement jump (CMJ); (4) a modified Wingate test from a stationary start, and (5) a 20 m running sprint with recorded split times at 2 m, 10 m and 20 m, and different interval times. Correlations between variables were performed using Pearson bivariate correlations. Differences between males vs. females for all variables were performed using independent t-tests and statistical significance was accepted at p < 0.05. Results: There were large and significant differences between males vs. females for almost all variables. The more meaningful variable differences (males vs. females, respectively) were peakWatts/kg (10.5 ± 1.7 vs. 7.5 ± 1.0), time to peak power (7.8 ± 1.6 vs. 9.2 ± 2.0 s), all sprint running variables, peak torque at 180/s/kg (1.5 ± 0.03 vs. 0.92 ± 0.34), and the isokinetic torque slope (−0.32 ± 0.12 vs. −0.24 ± 0.09). Assessing correlations and slope response differences for select variables between males and females revealed evidence in support of different physiology. For example, female subjects had <50% of the male slope profile for 10–20 m sprint performance vs. peakWatts/kg (−13.02 vs. −6.043W/kg/s), revealing the differences were more involved than simply being less physically fit. Slope differences were also seen in the isokinetic peak torque at 180◦/s data (−79.06 vs. −115.8 N m for males vs. females). Discussion: Multiple measures of muscular power during intense exercise were very different between males and females, even when correcting for body mass differences. The power profile of females differs to males, revealing more complex physiological determinants than simply mass, fitness or body composition correction. Further research needs to be conducted to ascertain the determinants to female vs. male muscular power, and quantify differences in chronic adaptations to intense exercise training.