Thesis (Ed. D.)--University of Massachusetts, Amherst, 2005. / Includes bibliographical references (leaves 243-254). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Thesis (Ed. D.)--University of Massachusetts, Amherst, 2005. / Includes bibliographical references (leaves 243-254).

Thesis (M.Sc.)--York University, 2005. Graduate Programme in Kinesiology and Health Science. / Typescript. Includes bibliographical references (leaves 59-63). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR11744

One of the most popular sports globally, soccer has seen a rise in the demands of the game over recent years. An increase in intensity and playing demands, coupled with growing social and economic pressures on soccer players means that optimal preparation is of paramount importance. Recent research has found the modern game, depending on positional role, to consist of approximately 60% more sprint distance in the English Premier League, which was also found to be the case for frequency and success of discrete technical actions (Bush et al., 2015). As a result, the focus on soccer training and player preparedness is becoming more prevalent in scientific research. By designing the appropriate training load, and thus periodization strategies, the aim is to achieve peak fitness in the most efficient way, whilst minimising the risk of injury and illness. Traditionally, training intensity has been based on heart rate responses, however, the emergence of tracking microtechnology such as global positioning system (GPS) and inertial sensors are now able to further quantify biomechanical load as well as physiological stress. Detailed pictures of internal and external loading indices such as these then combine to produce a more holistic view of training load experience by the player during typical drills and phases of training in soccer. The premise of this research is to gain greater understanding of the physical demands of common training methodologies in elite soccer to support optimal match performance. The coaching process may then benefit from being able to prescribe the most effective training to support these. The first experimental chapter in this thesis began by quantify gross training loads of the pre-season and in-season phases in soccer. A broader picture of the training loads inherent in these distinct phases brought more detail as to the type and extent of external loading experienced by soccer players at these times, and how the inclusion of match play influences weekly training rhythms. Training volume (total distance) was found to be high at the start compared to the end of pre-season (37 kilometres and 28 kilometres), where high cardiovascular loads were attained as part of the conditioning focus. This progressed transiently, however, to involve higher-speed, acceleration and change-of-direction stimuli at the end of pre-season compared to the start and to that in-season (1.18 kilometres, 0.70 kilometres and 0.42 kilometres high-intensity running; with 37, 25 and 23 accelerations >3m/s2 respectively) . The decrease in volume and increase in maximal anaerobic activity was evident in the training focus as friendly matches were introduced before the competitive season. The influence of match-play as being a large physical dose in the training week may then determine the change in weekly periodisation and how resulting training loads applied and tapered, if necessary. The focus of research was then directed more specifically to the most common mode of training in soccer, that also featured regularly in the pre-season period in the present study, small-sided games (SSG). The subsequent studies examined numerous manipulations of this specific form of soccer conditioning, such as player numbers as well as absolute and relative playing space available. In contrast to some previous literature, changing the number of players did not seem to influence training responses significantly, although playing format in the possession style brought about larger effects for heart rate (89.9%HRmax) and average velocity (7.6km/h-1). However, the following studies (Chapters 5, 6 and 7) revealed a greater influence of relative playing space available to players in SSG. The larger area at their disposal brought about greater aerobic responses (~90%HRmax), by allowing higher average and peak velocities (>25km/h-1), as well as greater distance acceleration behaviour at greater thresholds (>2.8m/s2). Furthermore, the data points towards space as being a large determinant in strategy of the player in small-sided games (SSG), subsequently shaping their movement behaviour and resulting physical responses. For example, higher average velocities in a possession format (8km/h-1) reflects higher work rate and heart rate load but makes achieving significant neuromuscular accelerations at a high level difficult given higher starting velocities prior to the most intense accelerations (4.2km/h-1). By altering space available and even through intentional numerical imbalances in team numbers, it may be easier for coaches to achieve the desired stimulus for the session or individual player, whether that is for aerobic and neuromuscular conditioning. Large effects were found for heart rate being higher in the underloaded team (85-90%HRmax) compared to the team with more players (80-85%HRmax) as well as for RPE (5AU versus 7AU). This was also apparent for meterage and therefore average velocity. It would also seem neuromuscular load through high acceleration and deceleration efforts were more pronounced with less numbers (given the need to press and close down opponents) and in a larger area relative to the number of players on the underloaded team. The peak accelerations and deceleration achieved was also higher when playing with less players (3-6.2m/s2 and 3-6.1m/s2) Having detailed ways in which to reach desired physical loading responses in common small training formats, Chapter 8 compared SSG to larger 9v9 formats with full-size 11v11 friendly matches. This enabled absolute and relative comparisons to be made and to understand the extent to which smaller training formats are able to replicate the required movements to be successful in competition. In relative terms, it was revealed that relative acceleration distance and Player Load were higher in smaller 4v4 games than match-play (1.1m.min-1 and 0.3m.min-1 >3m/s2; 16.9AU versus 12AU). Although the smallest format did not replicate the high-velocity demands of matches, the results confirmed their efficacy in providing significant neuromuscular load during the training week, which may then be supplemented by high-intensity interval running in order to gain exposure to more maximal speed work. In summary, the data presented provide valuable information from GPS and inertial sensor microtechnology which may then be used to understand training better to manipulate types of load according to physical conditioning objectives. For example, a library of resources to direct planning of drills of varying cardiovascular, neuromuscular and perceptual load can be created to give more confidence in session outcomes. Combining external and internal load data of common soccer training drills, and their application across different phases and training objectives may give coaches a powerful tool to plan and periodize training.

The aims of this thesis were to develop a time efficient field test of the distance-time relationship, assess its validity, reliability and sensitivity and utilise the test to monitor and prescribe endurance training in distance runners. Laboratory-based tests of the distance-time relationship often use lengthy recovery periods between trials, resulting in multiple visits and limiting their practical application. A field-based test, completed in a single visit, could improve the utility of the distance-time relationship. A novel single visit field test comprising of 3 constant-distance trials, separated by a 30-minute recovery, was designed. This test estimates the highest sustainable rate of aerobic metabolism, or critical speed (CS), and the modelled maximum distance performed above CS (D’). When compared to a traditional multi-visit laboratory protocol, field test CS was highly correlated (r=0.89, P0.05) and high typical error (334-1709 s). Non-linear modelling of recovery did not improve the accuracy. A high variability in D’ may in part explain the low predictive ability of the models. The conclusion from this thesis is that the single visit field test is a valid, reliable and sensitive test for CS, which provides a favourable alternative to multi-visit laboratory-based testing.

Critical Power (CP) provides a useful indicator of training status in continuous activities lasting between approximately 2 and 30 minutes. To date, determination of CP has been mostly constrained to the laboratory. The conventional laboratory protocol commonly requires multi-day time-to-exhaustion tests. The thesis below addresses whether CP can a) be determined without multi-day exhaustive trials and b) be determined in the field. Studies compared the findings of conventional laboratory determination methods with novel protocols in which either the testing mode, the recovery period between exhaustive trials, or the environment were manipulated. Study 1 demonstrates that the recently developed 3-min all-out protocol does not result in valid CP values, when using the isokinetic ergometer mode. Results indicated low levels of agreement (mean of 23-45 W) between conventionally determined CP and values derived through the 3-min all-out protocol. The average prediction error associated with the relationship between CP and the 3-min all-out End Power was 7%. In Study 2, values of CP derived through a conventional laboratory CP protocol were compared with those determined outdoors on a cycling track. High levels of agreement (mean of 2 -14 W) were observed between the laboratory and field values of CP. The average prediction error associated with the relationship between laboratory and field CP was 2.2%. Based in the laboratory, Study 3 compares a 24 h recovery protocol with a 3 h and a 30 min recovery protocols. High levels of agreement (mean of -2 - 11 W and -2 - 8 W respectively) were observed across protocols. The average prediction error associated with the relationship between the 24 h and 3 h and the 24 h and 30 min protocols was 2.4% and 3.3% respectively, suggesting that determination of CP could be made more ‘athlete-friendly’ by shortening the conventional 3-day protocol to one day. Study 4 uses three protocols to evaluate the shortened 30 min protocol in ecological valid open road conditions. Values of CP derived from laboratory protocols were compared to a) those derived from pre-planned and ‘grouped’ maximal efforts of 3 min, 7 min and 12 min with a 30 min recovery period between efforts (protocol 1), b) those of discrete and randomly performed, yet still pre-planned maximal efforts of the same durations (protocol 2), and c) to those extracted from self-directed training and racing of these same durations (protocol 3). The average prediction error associated with the relationship between the laboratory and the field values of CP was 3.1% (protocol 1), 4.9% (protocol 2) and 4.1% (protocol 3). Results, whilst providing high levels of agreement, also suggested that in particular protocols 1 and 3 potentially provide a practical and arguably ecologically valid alternative to the conventional laboratory protocol. Study 5 further investigates the overall CP determination procedure by comparing collected values of CP derived through 3 data points with both, CP laboratory and field values derived through 2 data points. High levels of agreement and low prediction errors (average 3.2%) associated with the relationship between 3 data points and 2 data points-derived CP were observed. Studies collectively provide support for the acceptance of field performance testing using CP, with either a 30 min inter-maximal effort recovery period or alternatively the extraction of non-planned specified maximal efforts from training and racing data. Overall the investigations described in the thesis suggest that CP determination is feasible beyond the laboratory and that consumer-level technology provides satisfactory ease and reliability of measurement in this context. Moreover, these novel CP determination methods allow coaches to continuously monitor their athletes.

Epidemiological studies have reported that ozone-pollution has a negative impact on human health. This pollutant is associated with high temperatures and is expected to continue to rise with the predicted global warming. People and athletes that exercise outdoors are of particular concern because, the more intense and the more prolonged the activity, the higher the ozone dose delivered to the lungs and potentially the higher the risk for performance impairment, lung function decrement, onset of lung inflammation, lung injury and oxidative stress. The main aim of the studies contained in this thesis was to evaluate the impact of ozone-pollution (0.1 ppm), heat and humidity on well trained runners taking part in an 8 km time trial run. Different end points were investigated for an analysis of the impact on performance outcome, lung function, lung inflammation and oxidative stress. In addition, a second aim was to investigate whether a 2-week supplementation period of vitamin C (500 mg•day-1) and vitamin E (100 IU•day-1) would provide any beneficial effects to the participants. The participants' lung function was measured by spirometry. Lung inflammation and oxidative stress status were assessed by a variety of markers both in the upper respiratory airways, by nasal lavage, and in the plasma. The markers assessed included: neutrophil count, clara cell protein (CC16), interleukin-8 (IL-8), uric acid, GSH/Protein and trolox equivalent antioxidant capacity. The results showed that the athletes performance was significantly decreased in the hot and humid condition (mean ± SD: 32min 35sec ± 2min 25sec) and in the hot, humid and ozone-polluted condition (33min 09sec ± 2min 44sec) when compared with the ozone alone condition (30min 27sec ± 2min 23sec) and the control condition (30min 15sec ± 1min 58seg). Ozone alone had little effect on the performance variable. The participants' lung function was not affected by the adverse environmental conditions. Evidence of early lung epithelial injury, however, was observed by an increase in CC16 in the upper respiratory airways immediately after the exercise trial in the hot, humid and ozone-polluted environment; though this was not observed for any other marker of inflammation at this time point. In this same adverse environmental condition, an increase in the GSH/Protein concentration in the upper respiratory airways was found immediately after the exercise. It was observed that the 2-week supplementation protocol improved the runners' time to complete the 8 km time-trial run in the hot, humid and ozone-polluted environment by 2.6%. In addition, the supplementation was shown to be effective in decreasing the lung inflammation induced by the combination of ozone pollution, heat and intense exercise. This was observed by a smaller increase in the concentration of CC16 in both the upper respiratory airways (0.67 ± 0.5 mg•l-1) and plasma (39.4 ± 17.4 ng•ml-1) in the vitamin treatment compared to the placebo. In addition, in the vitamin treatment the, cortisol concentration (29.2 ± 14.8 ng•ml-1) after the run, the IL-8 concentration (75.8 ± 43.2 pg•ml-1) and neutrophil percentage (22.6 ± 17.2 %) in the airways 6 h after the run were also reduced compared to the values in the placebo treatment (49.9 ± 13.4 ng•ml-1; 126.6 ± 103.2 pg•ml-1; 25.2 ± 22.6 % respectively). Taken into consideration together, these results provide evidence that heat and humidity combined with ozone have a detrimental effect on athletes' performance in an 8 km time trial, it cannot be discounted that this was simply due to the heat and humidity as there was no differences in the two heat performances. The hot, humid and ozone environment elicited an early epithelial damage characterized by increase in CC16 concentration in the airways. Moreover, an increase in the antioxidant concentration in the upper respiratory airways in that same trial, as indicated by the nasal lavage GSH/protein, suggests a protective mechanism against the oxidative stress stimulated by the high intensity exercise in association with ozone, heat and humidity. Heat and humidity alone had a similar detrimental effect in performance. While, ozone alone had little effect on the variables. In addition, it can be suggested that 2 weeks of a low dosage of vitamin C and E supplementation might present some benefits for the performance outcome and immune system of trained individuals when taking part in a running competition in an ozone-polluted, hot and humid environment. These benefits will, however, depend on the regulation of the antioxidants uptake and metabolism of each subject.

Limited research data is available outlining the resistance training characteristics of elite football players. The aim of the first study (Chapter 3) was to compare approaches to calculating resistance training volume during 4 weeks of pre-season training in 23 English Premier League footballers. Volume was calculated using four different methods of quantification; Repetition volume (RV), Set Volume (SV), Volume Load (VL) and Maximum Dynamic Strength Volume Load (MDSVL). Overall there was a significant difference between resistance training volumes calculated by the different methods used to monitor resistance training load (P < 0.001). More specifically, significant differences were observed between RV and SV methods (P < 0.001), RV and MDSVL (P = 0.001), SV and VL (P = 0.010), SV and MDSVL (P = 0.033) and VL and MDSVL (P = 0.002). Only RV and VL methods were similar in the information they provided on training load (P = 0.411). While the lack of a gold standard measure of volume makes it is unclear which, if any, method represents the most accurate measure of volume the discrepancies between methodological approaches highlight that these different approaches are not directly transferable as strategies to monitor resistance training. The understanding of the differences between each method may therefore enable appropriate, situation specific, approaches to be designed and implemented for both practical and research purposes. The aim of the second study (Chapter 4) was to analyse the resistance training loads completed by an elite professional football team across a competitive season. Resistance training data was collected from 31 elite football players competing in the English Premier League over a 46 week period in the 2012-2013 season. A total of 1685 individual training observations were collected during the pre-season and in-season competition phases, with a median of 42 training sessions per player (range = 9 – 124). Training load data was separated into 7 blocks of 6 weeks for analysis. These periods included pre-season (6 weeks duration) and in-season (40 weeks duration) phases. Set volume was selected as a measure of total volume. Data was analysed using 3 separate linear mixed modelling analysis using the statistical software package R (Version 3.0.1). Weekly resistance training frequency (mean±SD) ranged from 1±1 to 2±1 sessions per week during the pre and in season phases. Significant differences in session frequency were seen between weeks 1-6 and weeks 7-12 (pre-season) (P ˂ 0.05), weeks 7-12 and weeks 13-18 (P ˂ 0.05), and weeks 7-12 and weeks 37-42 (P ˂ 0.05). Mean weekly training volume ranged from 18±16 to 30±24 sets.wk-1. The total training volume demonstrates a clear minimum during weeks 7-12. Significant differences in total training volume were also observed between weeks 1-6 and weeks 7-12 (pre-season) (P ˂ 0.01), weeks 7-12 and weeks 13-18 (P ˂ 0.05), and weeks 7-12 and weeks 19-24 (P ˂ 0.05). There was no significant difference in training intensity between weeks 1-6 (pre-season) and weeks 7-12. Training intensity during weeks 1-6 however was significantly lower than during weeks 13-18 (P ˂ 0.05), 19-24 (P ˂ 0.01), 25-30 (P ˂ 0.01), 31-36 (P ˂ 0.05), and 37-42 (P ˂ 0.01). Training intensity during weeks 7-12 was also significantly lower than during weeks 13-18 (P ˂ 0.01), 19-24 (P ˂ 0.05), 25-30 (P ˂ 0.05), 31-36 (P ˂ 0.05), and 37-42 (P ˂ 0.001). The findings would suggest that resistance training loading is limited during different periods of the season. This is predominantly as a consequence of low training frequency, potentially due to a high prevalence of competitive fixtures. The aim of the third study (Chapter 5) was to attempt to quantify the impact of resistance training completed by players, through evaluating the change in the lower body power outputs of an elite professional football team across a competitive season. Resistance training data was collected from 22 elite football players competing in the English Premier League over a 38 week period. A total of 246 individual power output observations were collected during the in-season competition phase. Power output of the lower body was assessed using a pneumatic resistance leg press machine with software and digital display (Keiser Sports Health Equipment Inc., Fresno, Ca). Data was analysed by means of linear mixed modelling analysis using the statistical software package R (Version 3.0.1). Power outputs ranged from 2200W to 4078W with a mean value of 3022±374W. Linear mixed effects show a significant effect of week on power output across the season (coefficient= 7.76W, p=0.0132). Specifically, when accounting for within player effects, power output increased 7.76W per week during the season. Individual weekly power coefficients ranged from +39.9W to -18.13W per week, thus indicating that the trend for increased power output across the season is not uniform for all the players. These data may suggest that lower body power performance is maintained or minimally enhanced over the course of a full competitive season in elite football players. Combined with the training load data previously examined in this thesis it can be concluded that whilst one resistance training session per week may be sufficient to avoid in season de-training or minimally improve power performance in elite football players, a frequency of two sessions per week may be necessary to obtain significant performance enhancements. In our fourth study (Chapter 6) we provide two case studies that outline and evaluate a structured approach to increasing resistance training loading with the primary goal of developing strength and power during the competitive season in elite football players. The purpose of our initial case was to examine a resistance training programme to enhance strength and power performance, alongside body composition during a period of rehabilitation from injury. The study intervention commenced following two weeks of recovery following the “Laterjet” surgical procedure. Initial assessments were performed for body composition via dual-energy x-ray absorptiometry (DXA) (QDR Series Discovery A, Hologic Inc., Bedford, MA) and lower body power output via using a pneumatic resistance leg press machine with software and digital display (Keiser Sports Health Equipment Inc., Fresno, Ca). Assessments were repeated 8 weeks post-surgery, i.e. following 6 weeks of resistance training. The six-week intervention consisted of three strength training sessions per week for the initial 3 weeks, followed by 2 sessions per week for the subsequent 3 weeks. Training volume (number of sets) equalled a total of 20 sets total per session. Total increase in body mass over the intervention period equated to 5.4kg, of which 4.2 kg increase in lean mass and a 1.3 kg increase in fat mass. Peak power output increased by 21%. Power to weight ratio also increased by 4.4 %. These data illustrate that it is possible to increase physical performance when rapid short-term increase in resistance training load is completed. The purpose of our second case was to examine a resistance training programme to enhance both strength and power performance parameters during a full competitive season. The player plays as a goalkeeper, regularly playing for his club 1st team. Prior to the onset of this case study this player did not present with any current injuries. This season long intervention consisted of two phases of training. Phase 1 was 16 weeks in duration and represented the beginning to the mid-point of the season. During this phase the goal was to gradually and safely increase resistance training loading. Phase 2 was 20 weeks in duration and represented the mid-point to the end of the season. This phase represented a period of consistent high loading following the initial systematic increase in these variables. / Assessment data was collected at the beginning, mid-point and end of the 2013-14 season. The player was first assessed for body composition via DXA (QDR Series Discovery A, Hologic Inc., Bedford, MA). Secondly, lower body power output was assessed using a pneumatic resistance leg press machine with software and digital display (Keiser Sports Health Equipment Inc., Fresno, Ca). Finally, the player’s upper body strength was assessed via 6 repetition maximum assessments of the dumbell bench press and prone row. The player completed a mean weekly volume of 41±24 sets per week and a mean frequency of 2±1 sessions per week for the initial phase of the study. The player completed a greater mean weekly volume in the later phase of the season compared to the initial training period (65±28 set per week vs. 41±24 sets per week in the initial phase of the season). A greater mean session frequency was also associated with the second training phase (3±1 vs. 2±1 session per week). There was a total decrease in body mass over the initial intervention period of 4kg, of which 2.7kg decrease in fat mass and a further 0.9 kg decrease in lean mass. Over the second phase of the intervention there was a total increase in body mass of 1.2kg, of which 2.4kg increase in lean mass and 1.2kg decrease in fat mass. During the initial phase of training peak power output increased by 25%, whilst power to weight ratio increased by 30%. During the later phase peak power output increased by a further 9% whilst the power to weight ratio increased by a further 10%. Upper body pressing (Dumbell Bench press) and upper body pulling (Dumbell Prone pull) strength was also increased by 14% and 21% respectively during the initial phase and a further 19% and 24% respectively during the later phase of the season.

The game of soccer places various physiological demands on players, who are required to respond by carrying out a range of locomotor activities at different intensities. Such activity patterns contribute to a high energy turnover in both training and match-play, which in turn requires the intake of adequate fuel sources to sustain it. Adequate nutrient intake constitutes an important foundation for physical performance by providing fuel for biological work, both short and long term as required throughout the course of a soccer match. Despite the popularity of the sport worldwide, few studies investigating the effect of nutrition on performance in soccer have been conducted to substantiate the effect of optimal nutrition over the duration of a standard soccer match. This dearth of evidence has contributed in turn to a lack of specific nutrition guidelines for soccer players, coaches, sport scientists, nutritionists and club administrators. The aim of this thesis is to investigate the physiological, psychological and sociological aspects of nutrition and soccer, and posit a comprehensive nutritional framework to actively engage soccer players in adopting diets supportive of optimal performance in soccer training and match-play. The researcher set out by hypothesising that an optimal diet positively influences physical performance in soccer match-play. To test this hypothesis, a 90 h diet was developed for the participating semi-professional soccer players. Following implementation of the diet, a 90-minute soccer-specific simulation protocol, BEAST90mod was used to test its effects on physical performance in soccer. The remaining three inter-linked studies were longitudinal in nature, and carried out with participants forming part of the Malta U21 National Soccer Team. In the first instance, players’ habitual dietary intake, expenditure and energy balance was examined. The researcher then gathered information about the players’ knowledge, attitudes, habits, perceptions and barriers towards a diet conducive with optimal soccer performance. The same players finally underwent a 9-month nutritional education and support intervention, the efficacy of which was measured by the researcher throughout the intervention period. The principle aim of the research is to present findings that provide players and stakeholders in soccer a clear indication of the effects of specialist nutrition in soccer, and empower them with a range of appropriate tools and strategies as employed throughout the support programme. It ultimately seeks to improve physical performance in soccer training and match-play by informing sound individual and team approaches to nutritional decision-making.

Unstable shoes are a unique category of footwear that provide a training stimulus during casual wear. Reported therapeutic benefits have led to their commercial success, although enhancing muscle activations and balance, normally associated with instability training devices like wobble boards, are not as effective. Therefore, the aim of this thesis was to develop and evaluate an unstable shoe that provides continually unpredictable perturbations. The notion was that a more challenging, and varied instability, alike uneven terrain, would provide an enhanced training stimulus. The first study investigated if the developed shoe with irregular midsole deformations (IM) was more demanding, alike uneven terrain, it was compared to an irregular surface (IS) and a stable shoe-surface during treadmill walking and running. Generally, IM increased instability compared to the control, demonstrated by a more cautious gait pattern and posture at initial contact, and subjectively perceived as less stable whilst walking and running. Certain responses in IM were similar to IS, such as the increased variability of frontal ankle motion and maximum sagittal knee angle in stance phase. This is proposed to benefit IM wearers by improving the level of functional joint variability. The second study assessed if the varied instability of IM would be more de-stabilising than an unstable shoe (US) by comparing joint stability strategies during walking and running. Results revealed joint stiffness reorganisations between the ankle and knee in IM and US during loading. Further joint stiffness re-distributions and increased ankle co-contraction were found in IM compared to US, indicating additional adaptations are required for stability. The third study revealed IM may similarly be beneficial in gym training, as adaptations were also triggered in forward and lateral lunge movements to maintain stability. Increased gastrocnemius medialis and peroneus longus activations were required for the push-off phase in lunges, which related to ankle position. Investigating short-term training effects after regular IM wear was not feasible with the prototype developed, so instead a 6-week IS walking intervention was undertaken, as similar responses were found to IM during locomotion in the first study. Results showed no significant improvements to ankle muscle strength and postural balance compared to a control group, who did not undertake a training intervention. This research revealed IM provided an innovative stimulus that increased instability compared to an US and simulated certain responses to an IS. Unpredictable instability provided by footwear may have potential use for injury prevention and rehabilitation interventions, but future work needs to assess which populations it benefits.