Neuromuscular (NM) fatigue can be defined as an exercise-induced decrease in skill-based performance and/or capacity that originates within the NM system (i.e. between activation of the primary motor cortex to the performance of the contractile apparatus (Bigland-Ritchie, 1981)) (Boyas & Guével, 2011). NM fatigue is a fundamental component of athlete training and competition, required for both optimal adaptation and performance. However, in the short-term, NM fatigue can decrease performance and increase injury risk, whilst its accumulation can produce long-term deleterious performance and health consequences. Consequently, athlete fatigue monitoring is recommended for precise management of athlete training adaptation and recovery practices. Regular NM function measurement is a key component of athlete fatigue monitoring; still the best means of assessing fatigue-induced effects on NM function is presently unclear. A broader understanding of the most suitable NM testing methods, and associated NM constructs, would therefore be of value to sport practitioners. As elaborated below, this dissertation aimed to first identify the most suitable NM function test, and then develop the testing technique to better determine the NM responses associated with acute fatigue, an accumulation of exercise stress (i.e. accumulated fatigue), and post-exercise recovery. A secondary aim was to provide a greater understanding of the NM responses elicited by fatiguing exercise. First, the suitability of four NM function tests (e.g. countermovement jump (CMJ), squat jump (SJ), drop jump (DJ), 20-m sprint (SPRINT)) for the regular measurement of NM fatigue was examined. Assessment of test repeatability (mean coefficient of variation for various measures of force, velocity, power, impulse and flight time; SPRINT: 1.2%; CMJ: 3.0%; SJ: 3.5%; DJ: 4.8%) and sensitivity to NM fatigue (substantial post-exercise changes observed up to; SPRINT: 0-hr post; SJ: 24-hr post; CMJ & DJ: 72-hr post) revealed the CMJ test to be the most suitable, with it highly repeatable and sensitive to fatigue-induced changes immediately following fatiguing exercise and during post-exercise recovery. Subsequent investigations further explored the use of CMJ testing for NM fatigue detection. Second, CMJ responses to acute NM fatigue and during post-exercise recovery were examined in recreational athletes. As part of this process, two analytic approaches, anticipated to decrease measurement error and improve test sensitivity through the examination of CMJ mechanics, were utilised. Fatiguing exercise resulted in a biphasic recovery profile. Immediate decreases were evident in most CMJ variables (i.e. small-to-moderate changes), followed by mechanical changes indicative of NM fatigue (i.e. small changes in CMJ time- and rate-based variables) at 72-hour. Observation of mechanical changes at 72-hour, supported the use of the two adopted CMJ analytic approaches. Third, the developed methodology was used with elite snowboard-cross athletes to examine fatigue- and training-induced changes in NM function. Compared to concentric CMJ variables (i.e. peak/mean power/force/velocity), mechanical CMJ changes were more marked following both the fatiguing protocol (ES: moderate-to-large vs. small-to-moderate) and the 19-week training block (large-to-extremely large vs. small-to-very large). The more apparent mechanical changes observed in this highly-trained population (vs. the recreational athletes in Chapter 3) indicated that CMJ mechanical analysis may be of particular value in athlete populations. Fourth, the CMJ testing techniques were used to examine NM changes associated with accumulated fatigue (i.e. an accumulation of exercise and/or non-exercise stress) in a highly-trained population. Alongside increased training loads and decreased wellness, substantial changes in CMJ mechanics (e.g. time to peak force, force at zero velocity) and jump outcome (e.g. flight time, peak displacement) were observed, thereby supporting the inclusion of mechanical CMJ assessment for the monitoring of accumulated NM fatigue effects. This series of investigations support the use of CMJ testing for athlete NM fatigue monitoring, and highlight that NM fatigue can manifest as alterations in the mechanical strategies used to accomplish a task. These changes appear evident in response to acute fatigue (Chapters 3 and 4), alongside increases in training load (Chapters 4 and 5) and during post-exercise recovery (Chapter 3). Practitioners should therefore incorporate analyses of CMJ mechanics to provide a more comprehensive assessment of fatigue- and training-induced changes in NM function. / Graduate / gatherco@uvic.ca

The purpose of this dissertation was to better understand position specific physical qualities and how they relate to high speed running performance throughout the course of a competitive collegiate soccer season. The amount of literature devoted to female soccer players is scarce when compared to the vast amount of literature associated with male soccer players. The objectives of this dissertation were: 1) to determine if playing position has an influence on physical qualities such as speed, change of direction ability, countermovement jump performance, relative strength, rate of force development, and intermittent endurance capacity, 2) investigate the differences between high and lower caliber players as defined by minutes played per match when considering the physical qualities mentioned previously, 3) and finally to assess the influence of physical qualities and playing position on high speed running performance throughout the course of a competitive season. Data from 57 Division I Women’s Collegiate soccer players from a single institution were used. The influence of playing position and caliber of play on physical qualities were assessed using both laboratory and field based testing assessments. It appears that attacking based players (forward, wide midfielder, and attacking midfielder) were faster compared to defensive based players (central defensive midfielder, central defender, and goalkeeper) when assessed during 20 m sprint assessments and change of direction ability assessments. The only variable to differentiate between caliber of play was the Yo-Yo Intermittent Recovery Test – Level 1 (YYIRT1), indicating that higher caliber players possess greater intermittent endurance capacity compared to lower caliber players. Playing position was the major contributor when assessing high speed running performance during competition, explaining almost 70% of the variance. These findings highlight the impact of tactical factors on physical performance during competition and the need for position based assessments to better identify relevant physical qualities with respect to playing position in Division I Women’s Collegiate Soccer players. Further research is needed with a wider range of players from various levels to determine if these findings exist across all levels or are unique to the institution used during these investigations.

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Maximum physical performance tests appear to best reflect athletes’ training status and readiness to perform; however, it is unfeasible for practitioners to implement physical performance tests while trying to minimise the effects of fatigue during training. Subjective self-reported well-being measures have therefore been purported as a tool for monitoring athletes’ readiness to perform without exertion. The purpose of the current study was to establish the nature and strength of the relationship between changes in physical performance test scores and changes in well-being scores in student soccer players. For the purpose of this investigation, the physical performance test scores (jump height (JH), 10 m and 40 m sprint tests, 5-0-5 and YO-YO) and well-being scores (fatigue, energy, stress, motivation, soreness, sleep and total well-being score (TWS)) were collected for 48 male student soccer players at three time points (testing observation one: T1; testing observation two: T2; testing observation three: T3) over a period of two weeks in order to assess percentage change scores for physical performance test scores and well-being scores between T1 and T2, T2 and T3, and T1 and T3. Once percentage change scores (physical performance test scores and well-being scores) for each comparative pair of testing observations were calculated, Spearman’s rank order correlation coefficients (r) were calculated to evaluate the nature and strength of the relationships between changes in well-being scores and physical performance test scores. The principal findings of this study were that over two weeks of training, improved JH was associated with better motivation and worse fatigue, soreness and TWS. Faster 10 m and 40 m sprint times were associated with worse energy, stress, sleep and TWS. Faster 5-0-5 time was associated with worse fatigue, stress, sleep and TWS. Longer YO-YO distance was associated with worse motivation, stress, sleep and TWS. However, in many instances, correlations between physical performance test scores and well-being scores were small to trivial. Numerous contradicting correlations were also found across all comparative pairs of testing observations. The take-home message of this study is that subjective measures of well-being may not be purported as good measures for assessing athletes’ readiness to perform. Thus, physical performance tests are the ultimate indicator of athletes’ readiness to perform in this regard. Our findings suggest that during pre-season, worse well-being may be reported; however, athletes’ readiness to perform may not be negatively affected. Coaches and sport scientists should consider measuring both subjective self-reported measures of well-being and physical performance tests as these measures appear to be assessing two separate concepts. / Dissertation (MSc (Sport Science))--University of Pretoria, 2019. / Physiology / MSc (Sport Science) / Unrestricted

The purpose of this study was to compare changes in static and countermovement jump variables across a competitive season of collegiate soccer to estimated training load and subjective measures of fatigue. Monitoring data from 21 male collegiate soccer players were retrospectively examined. Nine vertical jump sessions occurred across the season in addition to daily training load assessment and daily mood-state assessment. Group average changes from the first testing session were calculated and compared to the group average training load for the 7 days preceding each vertical jump testing session for static and countermovement jump height and allometrically scaled peak power. Statistical analysis demonstrated strong relationships between changes in vertical jump height for both conditions, allometrically scaled peak power for static jumps, and estimated training load. The results indicate changes in static jump height and allometrically scaled peak power may be more useful athlete fatigue monitoring tools than countermovement jump variables.

Physiological performance has been commonly scaled for body size using various methods to scale anthropometrics, but a paucity of data exists on scaling muscle size. The aim of this thesis was to elucidate the optimal method to scale height (HT), body mass (BM), lean body mass (LBM), and muscle cross-sectional area (CSA) when scaling weightlifting performance for body size. 26 weightlifters (13 male, 13 female) participated in this study. The measurements collected were the snatch (SN), clean and jerk (CJ), isometric peak force (IPF), and countermovement jump height (CMJH). HT, LBM, BM, and vastus lateralis CSA were scaled using the ratio standard and allometry. Competition performance scaled for allometrically scaled CSA possessed greater relationships to CMJH (r = 0.60 – 0.78) than the ratio standard (r = 0.56 – 0.58). These findings suggest that allometrically scaling CSA may be superior when scaling weightlifting performance for CSA.

Chronic fatigue affects athletes' abilities to maintain force and power capabilities over the course of a season. The ability for sport scientists and coaches to monitor and manage fatigue is beneficial for all sports, especially those with lengthy seasons. Although methods of monitoring and managing fatigue have been suggested for various sports, there is currently limited research examining methods of monitoring fatigue in baseball over the course of a season. To effectively maintain peak performance, potential methods for monitoring and managing fatigue in baseball players need to be discussed.

Purpose: To examine the validity of 2 kinematic systems for assessing mean velocity (MV), peak velocity (PV), mean force (MF), peak force (PF), mean power (MP), and peak power (PP) during the full-depth free-weight back squat performed with maximal concentric effort. Methods: Ten strength-Trained men (26.1 ± 3.0 y, 1.81 ± 0.07 m, 82.0 ± 10.6 kg) performed three 1-repetition-maximum (1RM) trials on 3 separate days, encompassing lifts performed at 6 relative intensities including 20%, 40%, 60%, 80%, 90%, and 100% of 1RM. Each repetition was simultaneously recorded by a PUSH band and commercial linear position transducer (LPT) (GymAware [GYM]) and compared with measurements collected by a laboratory-based testing device consisting of 4 LPTs and a force plate. Results: Trials 2 and 3 were used for validity analyses. Combining all 120 repetitions indicated that the GYM was highly valid for assessing all criterion variables while the PUSH was only highly valid for estimations of PF (r = .94, CV = 5.4%, ES = 0.28, SEE = 135.5 N). At each relative intensity, the GYM was highly valid for assessing all criterion variables except for PP at 20% (ES = 0.81) and 40% (ES = 0.67) of 1RM. Moreover, the PUSH was only able to accurately estimate PF across all relative intensities (r = .92-.98, CV = 4.0-8.3%, ES = 0.04-0.26, SEE = 79.8-213.1 N). Conclusions: PUSH accuracy for determining MV, PV, MF, MP, and PP across all 6 relative intensities was questionable for the back squat, yet the GYM was highly valid at assessing all criterion variables, with some caution given to estimations of MP and PP performed at lighter loads.

The primary aim of this study was to examine the time course of change in muscle morphology and vertical jump performance in weightlifters preparing for a national competition. The secondary aim of this study is to examine how perceived recovery and stress state corresponds with alterations in training load leading up to competition. Eleven Olympic Training Site weightlifters completed a 4-week peaking phase for a national competition. Body mass, stress and recovery psychometric measures, and unloaded/loaded (20kg) squat jump height (SJH) were measured weekly and at the competition site. Vastus lateralis cross-sectional area (CSA), muscle thickness (MT) and pennation angle (PA) ultrasound measurements were taken prior to and following the training protocol. In competition, 6 athletes set a personal best in snatch, clean and jerk and/or total. These results suggest that improvements in the loaded SJ and psychometric measures correspond to successful competition performance in some weightlifters. Notably, most weightlifters appeared to be peaked within 3 days of competition.

Purpose: The purpose of this training, monitoring study was to investigate how alterations in training variables affect changes among underlying mechanisms of performance and weightlifting performance and whether certain variables are better suited for monitoring the training process than others. Additionally, the importance of including barbell displacement in volume load (VL) calculations was investigated. Subjects: Seven (4 males, 3 females) competitive weightlifters participated in the study dealing with alterations of underlying mechanisms and performance while 8 weightlifters (5 males, 3 females) participated in the investigation of exercise displacement. Methods: The weightlifters participated in a 20-week periodized resistance training plan. Measurements of maximal strength and explosive strength from the isometric mid-thigh pull (IMTP) and static jumps (SJ) with 0kg, 11kg, and 20kg were taken toward the end of each training block (weeks 1, 6, 10, 13, 17, and 20). Weightlifting performance was measured at weeks 0, 7, 11, and 20. The detailed monitoring of VL consisted of recording the load, rep count, and with and without displacement for every set for 20 weeks. Results: Very strong correlations were displayed between weightlifting performances and isometric rate of force development (RFD), isometric peak force (PF), and peak power (PP) at 0kg, 11kg, and 20kg. During periods of higher volume loads RFD was depressed to a much greater extent than peak force (PF). For the males, similar to RFD, JH at 20kg responded in a manner fitting an expected fatigue response compared to JH at 0kg and 11kg. VL correlated very strongly to VL with displacement; however, statistically significant differences existed for percent change (4 of the 7 time periods measured) Conclusions: PF is more resistant to volume alterations than RFD and JH at 20kg. Thus RFD and JH at 20kg appear to be superior monitoring metrics. The testing period in which preparedness was the highest happened in concert with a taper. Based on correlations, PF, RFD, and PP are variables on which coaches should focus for enhancing performance. A strong relationship exists between VL and VL with displacement; however, changes from one period to the next are not always the same.