1,149 research outputs found
Determinants of performance in paced and maximal 800-m running time trials
No full textPurpose: We aimed to identify the underpinning physiological and speed/mechanical
determinants of different types of 800-m running time trials (i.e., with a positive or negative
pacing strategy) and key components within each 800-m time trial (i.e., first and final 200-m).
Methods: Twenty trained male 800-m runners (800-m personal best time (min:s):
1:55.10±0:04.44) completed a maximal 800-m time trial (800MAX) and one pacing trial, whereby
runners were paced for the first lap and speed was reduced by 7.5% (800PACE) relative to 800MAX,
while the last lap was completed in the fastest time possible. Anaerobic speed reserve, running
economy, the velocity corresponding with VO2peak (VVO2peak), maximal sprint speed (MAXSS),
maximal accumulated oxygen deficit and sprint force-velocity-power profiles were derived from
laboratory and field testing. Carnosine content was quantified by proton magnetic resonance
spectroscopy in the gastrocnemius and soleus and expressed as a carnosine aggregate Z-score
(CAZ-score) to estimate muscle typology. Data were analysed using multiple stepwise regression
analysis.
Results: MAXSS and vVO2peak largely explained the variation in 800MAX time (r2
=0.570; P=0.020), while MAXSS was the best explanatory variable for the first 200-m time in 800MAX
(adjusted r2 =0.661, P<0.001). Runners with a higher CAZ-score (i.e., higher estimated
percentage of type II fibres) reduced their last lap time to a greater extent in 800PACE relative to
800MAX (adjusted r2 =0.413, P<0.001), while better maintenance of mechanical effectiveness
during sprinting, a higher CAZ-score and vVO2peak was associated with a faster final 200-m time
during 800PACE (adjusted r2 =0.761, P=0.001).
Conclusion: These findings highlight that diversity in the physiological and speed/mechanical
characteristics of male middle-distance runners may be associated with their suitability for
different 800-m racing strategies in order to have the best chance of winning
Impact of Lower Limb Muscle Morphology on Sprint Performance
No full textThe ability to rapidly accelerate and reach maximal sprinting velocity is paramount to success in running-based sports. However, there is a lack of scientific literature examining the muscular determinants of overground sprint acceleration and maximal velocity in athletes. The purpose of this study was to 1) identify the spatial patterns of lower limb muscle volumes and peak cross-sectional areas in sub-elite rugby league athletes who were affiliated with a National Rugby League (NRL) club; and 2) identify if spatial differences in normalised muscle volumes and peak cross-sectionals area were associated with 10-m sprint times, 30-m sprint times and peak sprint velocity. Nineteen male under-20 rugby league athletes (mean ± SD, age, 19.2 ± 0.7 years; height, 180.7 ± 5.6 cm; mass, 89.9 ± 10.0 kg) from a single NRL club, performed a series of 30-m sprints in order to derive 10-m sprint times, 30-m sprint times and peak sprint velocity. Magnetic Resonance (MR) imaging was used to calculate the normalised muscle volumes and peak cross-sectional areas of the gluteus maximus (GMAX), medius (GMED) and minimus (GMIN), tensor fascia latae (TFL), sartorius (SART), iliopsoas (ILIOP), gracilis (GR), adductor magnus, longus and brevis (ADD), rectus femoris (RF), vastus lateralis (VL), vastus intermedius (VI), vastus medialis (VM), semimembranosus (SM), semitendinosus (ST), biceps femoris long head (BFLH), biceps femoris short head (BFSH), soleus (SOL), gastrocnemius medialis (GM) and gastrocnemius lateralis (GL). Stepwise linear regression models were used to determine the extent to which sprint performance was explained by muscle morphology. The results revealed that variation in 10-m sprint times was best explained by ADD peak CSA (r2 = 0.582, p = 0.005) and TFL and VI normalised volume (r2 = 0.570, p = 0.026). Variation in 30-m sprint times were best explained by ADD, VI and VM peak CSA (r2 = 0.751, p = 0.030) and ILIOP and TFL normalised muscle volumes (r2 = 0.672, p = 0.021). Variation in peak sprint velocity was best explained by GMIN and GL peak CSA (r2 = 0.445, p = 0.029) and ILIOP, GL, RECF and ADD normalised muscle volume (r2 = 0.820, p = 0.035). The findings of this study demonstrate that sub-elite male rugby league athletes display non-uniform patterns of lower limb muscle size and suggest the possibility that preferential hypertrophy of the proximal hip- and knee-spanning muscles may have important implications for improving sprint acceleration and maximal velocity performance.Thesis (Masters)Master of Medical Research (MMedRes)School of Pharmacy & Med SciGriffith HealthFull Tex
Determinants of last lap speed in paced and maximal 1500-m time trials
No full textPurpose: The present study identified the physiological and performance characteristics that are deterministic during a maximal 1500-m time trial and in paced 1500-m time trials, with an all-out last lap.
Methods: Thirty-two trained middle-distance runners (n = 21 male, VO2peak: 72.1 ± 3.2; n = 11, female, VO2peak: 61.2 ± 3.7 mL kg−1 min−1) completed a 1500-m time trial in the fastest time possible (1500FAST) as well as a 1500MOD and 1500SLOW trial whereby mean speed was reduced during the 0–1100 m by 5% and 10%, respectively. Anaerobic speed reserve (ASR), running economy (RE), the velocity corresponding with VO2peak (VVO2peak), maximal sprint speed (MSS) and maximal accumulated oxygen deficit (MAOD) were determined during additional testing. Carnosine content was quantified by proton magnetic resonance spectroscopy in the gastrocnemius and expressed as a Z-score to estimate muscle fibre typology.
Results: 1500FAST time was best explained by RE and VVO2peak in female runners (adjusted r2 = 0.80, P < 0.001), in addition to the 0–1100-m speed relative to VVO2peak in male runners (adjusted r2 = 0.72, P < 0.001). Runners with a higher gastrocnemius carnosine Z-score (i.e., higher estimated percentage of type II fibres) and greater MAOD, reduced their last lap time to a greater extent in the paced 1500-m trials. Neither ASR nor MSS was associated with last lap time in the paced trials.
Conclusion: These findings suggest that VVO2 peak and RE are key determinants of 1500-m running performance with a sustained pace from the start, while a higher carnosine Z-score and MAOD are more important for last lap speed in tactical 1500-m races
Metabolic consequences of β-alanine supplementation during exhaustive supramaximal cycling and 4000-m time-trial performance
No full textThe present study investigated the effects of β-alanine supplementation on the resultant blood acidosis, lactate accumulation, and energy provision during supramaximal-intensity cycling, as well as the aerobic and anaerobic contribution to power output during a 4000-m cycling time trial (TT). Seventeen trained cyclists (maximal oxygen uptake = 4.47 ± 0.55 L·min−1) were administered 6.4 g of β-alanine (n = 9) or placebo (n = 8) daily for 4 weeks. Participants performed a supramaximal cycling test to exhaustion (equivalent to 120% maximal oxygen uptake) before (PreExh) and after (PostExh) the 4-week supplementation period, as well as an additional postsupplementation supramaximal cycling test identical in duration and power output to PreExh (PostMatch). Anaerobic capacity was quantified and blood pH, lactate, and bicarbonate concentrations were measured pre-, immediately post-, and 5 min postexercise. Subjects also performed a 4000-m cycling TT before and after supplementation while the aerobic and anaerobic contributions to power output were quantified. β-Alanine supplementation increased time to exhaustion (+12.8 ± 8.2 s; P = 0.041) and anaerobic capacity (+1.1 ± 0.7 kJ; P = 0.048) in PostExh compared with PreExh. Performance time in the 4000-m TT was reduced following β-alanine supplementation (−6.3 ± 4.6 s; P = 0.034) and the mean anaerobic power output was likely to be greater (+6.2 ± 4.5 W; P = 0.035). β-Alanine supplementation increased time to exhaustion concomitant with an augmented anaerobic capacity during supramaximal intensity cycling, which was also mirrored by a meaningful increase in the anaerobic contribution to power output during a 4000-m cycling TT, resulting in an enhanced overall performance.Griffith Health, School of Allied Health SciencesFull Tex
Characterising the movement patterns of women's beach volleyball using global positioning systems
No full textThe aim of this thesis was to describe the movement patterns of women’s beach volleyball using global positioning systems (GPS) technology. This aim was completed in two parts: Part A involved the investigation of the level of agreement between an emerging GPS system (VX Sport VX235 Log, Visuallex Sport International Ltd, Lower Hutt, New Zealand) and a well- established GPS system (Catapult MinimaxX S4, Catapult Innovations, Melbourne Australia). We recruited five semi-professional beach volleyball athletes who wore the two GPS units (sampling at 10 Hz) simultaneously during a training session which involved beach volleyball drills and simulated match-play. A paired sample t-test with statistical significant set to p<0.05 was applied to examine whether differences existed in the measurements of total distance (m), average speed (m∙min-1), max velocity (m∙s-1) and the distance (m) covered in five distinct velocity zones during a beach volleyball training session between the two different brands of GPS units. Significantly greater average speed (38.3 ± 5.66 m∙min-1, p = 0.009), and the distance covered between speeds of 4-8 km∙h-1 (248 ± 207 m, p = 0.008) and 16-20.5 km∙h-1 (8.78 ± 7.40 m, p = 0.006) were reported by the Catapult S4 units compared to the VX235 GPS units (35.9 ± 3.45 m∙min-1, 206 ± 168 m and 1.64 ± 2.62 m respectively), in conjunction with the VX235 units reporting a greater max velocity (4.37 ± 0.68 m∙s-1, p = 0.013) compared to the Catapult S4 units (4.07 ± 0.60 m∙s-1). These results demonstrate that differences exists between the emerging VX235 GPS system and the well-established Catapult S4 GPS system for measuring the movement patterns during beach volleyball, supporting the notion that further validation of GPS units against other practically applied and validated athlete movement trackers is required to further understand the ability of GPS systems to measure the movement patterns of beach volleyball.
Part B of this thesis involved the application of the 10 Hz VX235 GPS unit to quantify the movement patterns of women’s beach volleyball match-play. Specifically the VX235 GPS unit was worn by twenty female beach volleyball athletes during competition matches from the U23 Australian beach volleyball championship (n=10) and the Queensland Open tournament (n=10). The results form Part B of this thesis describe women’s beach volleyball athletes as covering a total distance of 555 ± 129 m and an average speed of 36.2 ± 3.2 m∙min-1, in addition to the majority of the distance covered occurred at speeds between 0-3.9 km∙h-1 (274 ± 63.6 m) and 3.9-7.8 km∙h-1 (203 ± 57.3) during match-play. The magnitude of these physical measures resulted in an average heart rate of 159 ± 12.0 bpm and 71.3 ± 30.4% of time with a heart rate ≤168 bpm. An independent sample t-test with statistical significant set to p5 points). A paired sample t-test with statistical significant set to p 5). In addition all physiological measures of heart rate displayed no significant difference between sets that ended with a small score margin and sets that ended with a large score margin with the exception of the percentage of time spent with a heart rate between 80-85% of each athletes age-predicted max heart rate which was significantly greater for sets that ended with a small score margin (25.8 ± 16.3%, p = 0.013) compared to sets that ended with a large score margin (16.0 ± 17.1%). The results from Part B of this thesis were the first to identify the movement patterns of women’s beach volleyball and provide insight into the presence of fatigue and the effect of score margin differential. The results provide information to assist in preparing women’s beach volleyball athletes for the demands they are likely to undertake during competitive match-play.Thesis (Masters)Master of Medical Research (MMedRes)School of Medical ScienceGriffith HealthFull Tex
Muscle Fiber Typology is Associated with Determinants of Performance in Elite-Level Swimmers
No full textThe determinants of sporting performance are important when attempting to identify and influence world-class and elite sporting results. This is highly relevant in swimming, as the complexities the aquatic environment creates for swimmers could mean that the determining characteristics could be of greater influence to their overall performance. However, the physiological determinants of world-class and elite swimming performance are underexplored in scientific research because of the complexity the water creates. For example, a protocol to measure gas exchange during swimming has not been developed with the level of accuracy, which can be obtained from a running on a treadmill or cycling on an ergometer. Consequently, research in swimming has primarily focused on the determinants that can be measured or monitored on land, opposed to in the water. In light of the restrictions or undeveloped methodology in swimming, the aim of this thesis was to explore a potential physical characteristic that could be deterministic of swimming performance – muscle fiber typology.
In study 1, peer-reviewed literature that described the age, height and body mass of Olympic level swimmers was reviewed to better understand whether these characteristics were deterministic to performance at the highest level of swimming competition, and whether these are still valuable to assess. In addition to this collation of literature, this study also assembled original data on the age, height and body mass of freestyle swimmers at the 1968, 1992 and 2016 Olympic Games. Data from all 4 swimming strokes was also collected form the 2016 Olympic Games in order to describe the current state of these characteristics in world-class swimmers. This assemblage of data highlighted that both female and male FR swimmers were taller at the 1992 (175.0 ± 6.1 cm and 189.0 ± 6.7 cm) Olympic Games compared to FR swimmers at the 1968 (168.2 ± 4.1 cm and 180.9 ± 5.8 cm) Olympic Games and there was no further significant changes in height from 1992 to 2016 (173.2 ± 6.5 cm and 189.0 ± 6.3 cm). Body mass followed the same trend with both females and males increasing from 1968 to 1992 (58.8 ± 0.8 kg to 63.6 ± 0.9 kg; 76.0 ± 0.8 kg to 80.5 ± 0.9 kg respectively) and then also plateauing from 1992 to 2016 (2016: 64.6 ± 0.7 kg and 80.5 ± 0.8 kg). However, the age of female and males differed; female swimmers continually increased in age from 1968 to 1992 to 2016 (16.7 ± 2.1, 19.7 ± 2.4 to 22.7 yr) whereas the male swimmers’ age followed a similar trend and plateau to height and body mass (20.1 ± 2.4, 21.8 ± 2.9 to 22.6 ± 2.8 yr). The plateau in age (males only), height and body mass, suggested that these characteristics may be exhausted in their ability to be deterministic of swimming performance at the world-class and elite level. Indeed, these characteristics could not differentiate between truly world-class swimmers and their elite counterparts. Therefore, it was concluded that new or alternative physical determinants of performance warranted exploration in order to provide new avenues for swimming coaches and applied sports scientists to progress the training and talent identification process of elite swimmers.
With new determinants of swimming performance needing to be explored, and a novel non-invasive method of determining muscle fiber typology recently developed, the consequent studies directed their focus on the influence muscle fiber typology has on the key performance determinants. The non-invasive estimation of muscle fiber typology is determined from the measurement of muscle carnosine which is a stable intramuscular metabolite that is two-fold higher in concentration in type II muscle fibers. Study two and three specifically investigated the influence muscle fiber typology has on race specific determinants of performance. Study 2 recruited 46 world-class swimmers, determined their muscle fiber typology using the non-invasive protocol and investigated the influence muscle fiber typology had on the start and turn segments of career best competitive performance. The results suggested that muscle fiber typology was not found to be influential in start time, turn time or turn out time when swimmers competing in all strokes and events were collectively analysed. However, when the start, turn and turn out time were found to be significantly faster in 100-m events compared to events greater than 200-m. It was then discovered that those swimmers who possessed a greater estimated proportion of type II muscle fibers had a quicker start time to 15 m (p = 0.02), whereas turn time and turn out time were not found to be significantly influenced by muscle fiber typology (p = 0.12 and 0.12 respectively). From a practical perspective this was highlighted in the 100-m freestyle, whereby swimmers with a greater estimated proportion of type II muscle fibers were 0.25 s (CI 90%, 0.17 s) faster to 15 m.
Study 3 investigated how the pacing strategy of 200-m freestyle swimmers was influenced by muscle fiber typology. After the recruitment of 25 world-class 200-m freestyle swimmers, they too had their muscle fiber typology estimated with the non-invasive methodology, and it was determined that swimmers with divergent muscle fiber typology did pace the 200-m freestyle differently. Swimmers with greater estimated proportions of type II muscle fibers spent a significantly larger percentage of overall race time on the third lap compared to those swimmers with greater estimated proportions of type I fibers (p = 0.02). It was highlight that this difference could be because of the energetic demands of this lap may be preferential for swimmers with greater proportions of type I muscle fibers given that this lap has the greatest contribution from aerobic energy metabolism. Interestingly, the overall performance times did not differ when swimmers with greater estimated proportions of type II fibers were compared to those with greater proportions of type I fibers. In contrast, there were substantial difference in the relative percentage of time spent on each lap. It was concluded that muscle fiber typology is influential in the pacing strategy of swimmers competing in the 200-m freestyle event, and consequently the relationship between pacing strategy of other events should be explored in relation to muscle fiber typology.
Study 3 highlighted that the marked differences in pacing strategy could be due to the physiological characteristics of different muscle fibers. Therefore, it seemed warranted to explore how different physiological and performance determinants of overall swimming performance are influenced by training volume and whether the muscle fiber typology is a moderating factor in the responses to training volume. Since physiological tests in swimming are under established, the final study implemented a number of swimming performance tests to determine their relationship with muscle fiber typology. Study 4 recruited 10 elite swimmers for a 7 wk training intervention study that increased the training volume by ~ 30% for 3 wk. The key finding from this study was that 200-m time trial performance was significantly impaired following the period of increased volume training (p < 0.01), and the change in time trial performance from pre- to post high volume training was positively associated with muscle fiber typology (r = 0.697, p =0.025). That is, swimmers with a greater estimated proportion of type II muscle fibers had larger decrements in performance.
The findings of this thesis demonstrate that the muscle fiber typology of world-class and elite swimmers is deterministic of swimming performance. It was initially found that previously researched determinants of performance (i.e., age, height and body mass) had started to plateau and may be less relevant for predicting performance, and therefore the exploration of a new determinant of performance is warranted. In light of this, it was found that the novel non-invasive technique to determine muscle fiber typology with the use of magnetic resonance spectroscopy is user friendly in the perception of world-class swimmers and coaches and therefore can be used to study such populations. The muscle fiber typology of swimmers influences determinants of race performance, including the start performance of swimmers in 100-m events and the pacing strategy of swimmers competing in the 200-m freestyle event. The results not only highlight the direct impact muscle fiber typology has on race performance, but also the necessity to individualise racing and training performance in relation to a swimmers muscle fiber typology. Muscle fiber typology has been deemed a moderating factor in how swimmers respond to training overload, with swimmers of greater proportions of type II muscle fiber having greater decrements in performance following high volume training, when compared to those swimmers who possess greater estimated proportions of type I fibers. Collectively, the findings from this group of studies show that muscle fiber typology is influential in the racing and performance determinants of swimming. This research is multi-faceted in that it adds to the knowledge of muscle fiber typology; it’s interaction with swimming performance, and also offers suggestions for how this research can be further explored in the swimming world. Furthermore, this body of work has determined that the non-invasive measurement of muscle fiber typology is embraced by world-class coaches and swimmers.Thesis (PhD Doctorate)Doctor of Philosophy (PhD)School Allied Health SciencesGriffith HealthFull Tex
Determining Optimal Gear Selection and Cadence in Elite Track Cyclists
No full textSelecting the most appropriate gear ratio in track cycling is integral for optimising performance, given the fixed gear ratio on track bicycles. For the flying 200-m time trial (i.e., f200-m track sprint), a gear ratio that facilitates the production of maximal power output (Pmax) is required. Similarly, during standing start events (i.e., pursuits, team sprint, Kilo), a balance between maximising the power production during the acceleration phase and maintenance phase is necessary. Currently, there is no systematic approach to identify and optimise gear ratios for individual athletes specific to their physiological characteristics, individual events, and environmental conditions. As such, within this thesis we will propose a methodological approach to personalise the optimisation of gear selection. This will be accomplished through the following objectives i) critically reviewing the relationship between muscle fibre typology (ratio of Type I and Type II fibres) and cycling efficiency, ii) investigating the impact of muscle fibre typology on cycling efficiency and track sprint cycling characteristics, iii) exploring the validity and agreement of field and laboratory-derived torque-cadence and power-cadence profiles, iv) investigating the effect of cadence on fatigue during maximal sprint cycling, and v) proposing a novel application of these findings to a physics-based model of track sprint cycling to identify individualised optimal gear ratios. [...]Thesis (PhD Doctorate)Doctor of PhilosophySchool of Health Sci & Soc WrkGriffith HealthFull Tex
Strong, Fast, Fit, Lean, and Safe: A Positional Comparison of Physical and Physiological Qualities Within the 2020 Australian Women's Rugby League Team
No full textMinahan, C, Newans, T, Quinn, K, Parsonage, J, Buxton, S, and Bellinger, P. Strong, Fast, Fit, Lean, and Safe: A positional comparison of physical and physiological qualities within the 2020 Australian Women's Rugby League team. J Strength Cond Res XX(X): 000-000, 2021-The purpose of the present study was to report the physical and physiological characteristics of elite women Rugby League (RL) players. Thirty-nine women (25.6 ± 4.3 years, 171.3 ± 7.7 cm, 83.5 ± 13.9 kg) from the 2020 Australian women's RL squad were recruited for this study. Players were categorized as adjustables (n = 7), backs (n = 15), or forwards (n = 17) for analysis. Each player was assessed for anthropometry, body composition (dual-energy X-ray absorptiometry), speed (5, 10 and 20 m sprint times), lower-body power (countermovement jump), upper-body power (medicine ball throw and explosive push up force), estimated one repetition maximum (e1RM) bench press, squat and bench pull, isometric mid-thigh pull strength, eccentric knee flexor strength, isometric hip abduction and adduction, and intermittent endurance performance (30-15 intermittent fitness test; 30-15 IFT). Linear mixed models were performed to compare positional groups. Forwards were significantly heavier and had greater fat mass, fat-free mass, and body fat percentage compared with backs and adjustables (P < 0.01). Backs were faster over 20 m compared with forwards (P = 0.025), whereas forwards had a lower 30-15 IFT peak velocity and estimated V[Combining Dot Above]O2peak compared with backs and adjustables. Nonetheless, when including body mass in the model, there were no differences between groups in 30-15 IFT peak velocity. There were no significant differences in other variables. These results provide contemporary benchmark physical, physiological, and anthropometric data for elite women RL players, which can inform recruitment, selection, training, and testing.No Full Tex
Relationships among Muscle Fibre Typology, the Force-Velocity-Power relationship, and the Force-velocity profile during the Squat Jump and Sprinting
No full textBackground: Sport Science researchers have validated a novel methodology to determine the force-velocity profile (SFv) which can be optimized in the vertical profile to maximise an athlete’s power production. This profile represents an extension upon the well-known force-velocity-power relationship (FVPr) which is based on the 1938 Hill model. Early muscle physiology researchers identified that different skeletal muscle fiber typology (MFT) exist and have categorized these fiber types according to contractile characteristics, enzyme activities, morphological, and metabolic properties. The physiological characteristics between MFT display differences in maximum shortening velocity and time to fatigue, which results in contrasting force-velocity-power (FVP) production capabilities during exercise. Human MFT is thought to be largely determined genetically, with little influence from external stimulus (i.e., exercise training), leading to a predisposition for sporting success along a sporting domain spectrum, from sprint to endurance sports. Within elite sport, athletes are tested for jumping and sprinting performance to determine; the suitability of an athlete to a given sport, identify the needs of an athlete, the responses to training, and preparedness of athletes for elite competition. Much research has investigated the FVPr variables and the SFv during jumping and sprinting. To date however, research is yet to investigate important relationships among MFT, the FVPr, and the SFv during jumping and sprinting. As such, further experimental research is required to determine such relationships, and provide important implications for performance professionals and researchers alike.
Objectives: The primary objective of the research study was to to investigate apparent relationships between MFT and the mechanical variables of the SFv and the FVPr during the squat jump and sprinting. A secondary aim was to consider how those relationships may influence exercise performance.
Methodology: Nineteen developing rugby league (RL) athletes were assessed for MFT, as well as the mechanical variables derived from the force- velocity-power (FVP) profiles during the squat jump and sprinting. The FVPr and SFv mechanical variables were acquired by using the computational method for both jumping and sprinting. For jumping, the participants were required to complete a series of un-loaded and loaded barbell squat jumps, whereby the highest jump from each trial was used to determine the jumping FVPr and SFv. For sprinting, two trials of 30 m sprints were completed, whereby split times were recorded at 5 m intervals. The fastest trial from each participant was used to determine the sprinting FVPr, SFv, and mechanical application of force variables. Proton magnetic resonance spectroscopy (1H-MRS) was used to quantify carnosine concentration in the gastrocnemius muscle in order to estimate MFT. The carnosine concentration was compared to that of a control population of active, non-athlete males (n=40), whereby an individual carnosine Z-score was derived for the RL athletes. Carnosine Z-score MFT groups were formed using the known group difference technique, whereby all carnosine Z-scores above zero formed the positive carnosine MFT group (n=9), and below zero formed the negative carnosine MFT group (n=10). SPSS (v26) was used to perform t-tests and spearman’s correlations to determine significant differences and relationships between carnosine Z-score MFT groups and the mechanical variables, while Microsoft Office Excel (2016) was used to analyse group variables data (sample size, mean, and standard deviation) acquired by the t-tests, to calculate Cohen’s d effects size.
Results: MFT was not found to influence the SFv during jumping or sprinting, however, MFT was found to influence the FVPr, with differences for force, velocity, and power between MFT. Moderate associations were also found between carnosine Z-score and the mechanical variables (force-velocity-power). Maximal power output (PMAX) was significantly different between carnosine Z-score MFT groups during jumping (p= 0.041, d=1.01), and was moderately associated with MFT (r=0.598**). PMAX (W/kg) was thought to be most influenced by VO (m/s) (p=0.073, d=0.88) but not FO (N/kg) during the squat jump. FO (N/kg) was not significantly different between groups (p=0.920, d=0.05) and had a negligible association with MFT (r= -0.032). During sprinting the SFv was not significantly different between groups (p=0.224, d=0.58) and was not considered to be influenced by MFT (r= -0.053). PMAX (W/kg) during sprinting was found to have a significant difference between MFT groups (p=<0.001, d=2.12), and seemed to be most influenced by FO (N/kg) (r=0.858**). FO (N/kg) was also significantly different between groups (p=0.019, d=1.19), while VO was not (p=0.216, d=0.59), and VO had a low association to PMAX (r=0.030). PMAX was found to influence RFMAX with a very high correlation (r=0.993**) and RFMAX was found to be significantly different between MFT groups (p=0.001, d=1.97). Exercise performance was most associated with PMAX in both jump height (m) (r=0.801**) and 30-m sprint time (s) (r=-0.893**), and resulted in significant and highly significant differences between groups for the squat jump (p=0.038, d=1.03) and the 30-m sprint time (s) (p=<0.001, d=2.54).
Conclusion: Variation in MFT was not associated with variation in the SFv during the squat jump or sprinting, despite being associated with various mechanical variables derived from the FVPr. MFT was found to influence PMAX differently during the squat jump when compared to sprinting. This is thought to be due to the low velocity constraints of the Squat jump, compared to the high velocity motion of sprinting, which highlights the difference in force production capabilities at high velocities for type IIa/ IIx MFT (Aagaard & Andersen, 1998; Tihanyi, Apor, & Fekete, 1982). The magnitude of difference between PMAX (W/kg) in sprinting when compared to the squat jump supports this inference, and is thought (Aagaard & Andersen, 1998; Tihanyi et al., 1982) to have occurred due to the low velocity constraints during the squat jump. To confirm this finding, future studies investigating associations between MFT and the FVPr, should compare FVP mechanical variables between the squat jump and high velocity jumps, such as a counter movement jump or drop jump. Future research should also aim to determine PMAX (W/kg) thresholds as associated to carnosine Z-score to better advise practitioners in the field; during baseline testing, with exercise prescription, during athlete performance monitoring, and determining athlete suitability for elite sport. While this study has determined an association between MFT, the FVPr, and has demonstrated that MFT has likely influenced the associated exercise performance. It is possible other muscle morphology differences within these groups (pennation angle and cross-sectional area), may also contribute to performance differences found, and is a recommendation for future investigation.Thesis (Masters)Master of Medical Research (MMedRes)School of Medical ScienceGriffith HealthFull Tex
A William Faulkner Remembrance
No full textA day-long program marking the fiftieth anniversary of William Faulkner’s death: 6:30 a.m. to 3:30 p.m. Marathon reading of The Reivers at Rowan Oak (917 Old Taylor Road) 4:15-5:45 p.m. Keynote lectures by author Randall Kenan and biographer Phillip M. Weinstein at Lafayette County Courthouse (1 Courthouse Square). Program for young readers at Square Books Jr. (111 Courthouse Square). 6:00-7:00 p.m. Book signings by Kenan and Weinstein at Off Square Books (129 Courthouse Square) 8:00-10:00 p.m. Screening of The Reivers (1969 adaptation, starring Steve McQueen) at Lyric Theater (1006 Van Buren Avenue
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