A biomechanical investigation of contemporary powerlifting training practices and their potential application to athletic development.

The contemporary training practices of powerlifters are presently being adopted by athletes from a variety of sports, seeking to improve their performance. The aims of this PhD were to: 1) identify the contemporary training practices of powerlifters; 2) investigate the biomechanical stimulus the training practices create; and 3) assess whether the training practices have the potential to improve the athletic performance of general athletes. The aims were achieved through the completion of five related studies. The first study employed questionnaires and interviews to identify the contemporary training practices used by elite powerlifters. The results demonstrated that elite powerlifters used a wide variety of training practices, many of which would not have been attributed to the group based on previous literature. The practices were categorised based on their underlying mechanical principles, so that the essential features could be investigated in the subsequent studies. A regression-based approach was used in the second study to identify the biomechanical variables associated with performance of common sporting tasks. Maximum force production, power, velocity and rate of force development (RFD) were shown to explain a large percentage of variation in performance of tasks such as sprinting, jumping and changing direction (adjusted R2 ranged from 0.43 to 0.86). These mechanical variables were then measured in a series of experimental studies to assess the potential of the contemporary powerlifting practices to improve athletes' physical performance. Assessments were based on a central paradigm in strength and conditioning, which asserts that improvements in the ability to express biomechanical variables (e.g. force and power) are best obtained with training practices that maximise acute production of the same variable. Based on the categorisation of the mechanical principles underlying the assessed training practices, three experimental studies were conducted that investigated: 1) the practice of performing traditional resistance exercises at maximum velocity; 2) the effects of manipulating the external resistance through the use of variable resistance material (chain resistance) and an unconventional barbell (the hexagonal barbell); and 3) the effects of altering the movement strategy used to perform the squat. The results of the studies clearly demonstrated that each of the practices investigated could be used to substantially alter - and, in most cases, enhance - the biomechanical stimulus created. The practice of performing traditional resistance exercises at maximum velocity revealed that all key mechanical variables were significantly increased (p < 0.05) compared with the standard practice of performing repetitions with a sub-maximum velocity. The results additionally demonstrated that, when performing a traditional resistance exercise such as the deadlift at maximum velocity, experienced resistance trained athletes could accelerate the load for the majority (75% to 90%+) of the movement. The second experimental study featuring the separate use of chain resistance and the hexagonal barbell to alter the characteristics of the external resistance demonstrated contrasting effects. The change in position of the external resistance when using the hexagonal barbell significantly (p < 0.05) increased the participants' ability to produce high force, power, velocity and RFD values across a range of loads in comparison with the same movement performed with a traditional straight barbell. In contrast, the results from the study evaluating the effects of adding chain resistance showed that, whilst force values were increased with the addition of chains, velocity, power and RFD values substantially decreased compared to standard repetitions performed with only barbell resistance. The results also demonstrated that the effects of the chain resistance were more noticeable with heavier chain and barbell loads. The final experiment investigated the effects of altering the movement strategy used to perform the back squat exercise. The results confirmed that changes to the movement strategy had a significant effect on a range of kinematic and kinetic variables. In particular, the contemporary techniques promoted by powerlifters resulted in substantial kinematic and kinetic changes at the hip and reduced kinetic output at the ankle joint. Collectively, the work from this PhD supports the selective use of contemporary powerlifting training practices for the development of athletic potential. Future research should build on the framework created in this thesis, progressing to longitudinal and ultimately implementation studies to increase the likelihood of transferring the results to practice

Comparative effect size distributions in strength and conditioning and implications for future research: a meta-analysis.

Controlled experimental designs are frequently used in strength and conditioning (S&C) to determine which interventions are most effective. The purpose of this large meta-analysis was to quantify the distribution of comparative effect sizes in S&C to determine likely magnitudes and inform future research regarding sample sizes and inference methods. Baseline and follow-up data were extracted from a large database of studies comparing at least two active S&C interventions. Pairwise comparative standardised mean difference effect sizes were calculated and categorised according to the outcome domain measured. Hierarchical Bayesian meta-analyses and meta-regressions were used to model overall comparative effect size distributions and correlations, respectively. The direction of comparative effect sizes within a study were assigned arbitrarily (e.g. A vs. B, or B vs. A), with bootstrapping performed to ensure effect size distributions were symmetric and centred on zero. The middle 25, 50, and 75% of distributions were used to define small, medium, and large thresholds, respectively. A total of 3874 pairwise effect sizes were obtained from 417 studies comprising 958 active interventions. Threshold values were estimated as: small = 0.14 [95%CrI: 0.12 to 0.15]; medium: 0.29 [95%CrI: 0.28 to 0.30]; and large = 0.51 [95%CrI: 0.50 to 0.53]. No differences were identified in the threshold values across different outcome domains. Correlations ranged widely (0.06 ≤ r ≤0.36), but were larger when outcomes within the same outcome domain were considered. The finding that comparative effect sizes in S&C are typically below 0.30 and can be moderately correlated has important implications for future research. Sample sizes should be substantively increased to appropriately power controlled trials with pre-post intervention data. Alpha adjustment approaches used to control for multiple testing should account for correlations between outcomes and not assume independence

Workplace interventions to improve sitting posture: a systematic review.

Evaluate the effectiveness of workplace interventions to improve sitting posture of workers that spend long periods of time seated at a visual display terminal. A systematic review of randomised controlled trials, non-randomised controlled trials and single-group intervention trials featuring workplace interventions with pre- and follow-up measurements of sitting posture was conducted (registered in PROSPERO, CRD#42015027648). Nine databases were searched for studies available between January 2005 and February 2016. 2519 articles were screened with 12 studies meeting the inclusion criteria. The included studies featured various ergonomic workplace interventions and comprised 4 randomised controlled trial (n = 457), 2 non-randomised controlled trials (n = 416) and 6 single-group intervention trials (n = 328). Due to clinical and methodological heterogeneity, pooling of data was not completed and a narrative summary of findings was developed using the Grading of Recommendations Assessment Development and Evaluation (GRADE) framework. The evidence for four review outcomes was assessed with medium to large positive improvements obtained for the majority of studies investigating changes to gross sitting posture, whereas mixed findings were obtained for more specific local segment assessments of sitting posture. The overall evidence quality for all review outcomes were identified as either 'low' or 'very low'. There is evidence which is limited in quality to indicate that ergonomic workplace interventions can improve gross sitting posture. More high quality research across a range of intervention types is required with longer follow-up durations and more advanced methods to assess sitting posture with greater frequency and less bias

Dose-response modelling of resistance exercise across outcome domains in strength and conditioning: a meta-analysis.

Resistance exercise is the most common training modality included within strength and conditioning (S&C) practice. Understanding dose-response relationships between resistance training and a range of outcomes relevant to physical and sporting performance is of primary importance for quality S&C prescription. The aim of this meta-analysis was to use contemporary modelling techniques to investigate resistance-only and resistance-dominant training interventions, and explore relationships between training variables (frequency, volume, intensity), participant characteristics (training status, sex) and improvements across a range of outcome domains including maximum strength, power, vertical jump, change of direction, and sprinting performance. Data were obtained from a database of training studies conducted between 1962-2018, which comprised healthy trained or untrained adults engaged in resistance-only or resistance-dominant interventions. Studies were not required to include a control group. Standardized mean difference effect sizes were calculated and interventions categorized according to a range of training variables describing frequency (number of sessions per week), volume (number of sets and repetitions performed), overall intensity (intensity of effort and load, categorised as low, medium, or high), and intensity of load (represented as % 1RM prescribed). Contemporary modelling techniques including Bayesian mixed effects meta-analytic models were fitted to investigate linear and non-linear dose-responses with models compared based on predictive accuracy. Data from a total of 295 studies comprising 535 groups and 6710 participants were included with analyses conducted on time points ≤26 weeks. The best performing model included: duration from baseline, average number of sets, and the main and interaction effects between outcome domain and intensity of load (%1RM) expressed non-linearly. Model performance was not improved by the inclusion of participant training status or sex. The current meta-analysis represents the most comprehensive investigation of dose-response relationships across a range of outcome domains commonly targeted within strength and conditioning to date. Results demonstrate the magnitude of improvements are predominantly influenced by training intensity of load and the outcome measured. When considering the effects of intensity as a %1RM, profiles differ across outcome domains with maximum strength likely to be maximised with the heaviest loads, vertical jump performance likely to be maximised with relatively light loads (~30%1RM), and power likely to be maximised with low to moderate loads (40-70% 1RM)

Effects of self-monitoring of heart rate and additional sprint running on exercise intensity and technical performance during small-sided games in soccer.

The purpose of this study was to assess whether relatively simple interventions including self monitoring of heart rate and the use of targeted sprints for those with the lowest relative HR values (%HRmax) could be used to increase exercise intensity during small sided games (SSGs) in soccer. A secondary aim of the study was to assess the effect of these interventions on overall gameplay. Fourteen male semi-professional players performed SSGs (6 vs. 6) under four conditions including a control, a self-monitoring approach where players monitored their own HR via a wristwatch, and two sprint conditions where players with HR values below 90%HRmax performed sprints either during the game or during the recovery period between games. A linear mixed effects model was used to test for main effects whilst accounting for covariances between observations made on the same player. The results identified relatively small but significant differences in average %HRmax (p<0.001) and RPE values (p<0.001) between the three modified conditions and the control. No significant differences were found between any of the modified conditions for measures of exercise intensity. On average, the modified conditions resulted in a 3.7% increase in %HRmax values and a 9.3% increase in RPE. The results from this study demonstrate that exercise intensity of SSGs in soccer can be increased by relatively simple and practical manipulations, the most basic of which requires only the use of inexpensive HR monitors

Spatial-temporal metrics to assess collective behavior in football: a systematic review and assessment of research quality and applicability.

Extensive research has been conducted to investigate collective behaviour of football players using spatial-temporal data. The purpose of this systematic review was to synthesise and evaluate the applicability of this research by reviewing information presented in previous studies and its capacity to clearly describe the analysis approaches and practical applications of findings. Eighty-five studies were included in the review with approaches assigned to 4 categories of metrics (1: spaces; 2: distances; 3) position; 4: numerical relations) and 2 analysis methods (predictability and synchronisation). The review identified that authors descriptions of metrics generally focussed on operationalised definitions and provided limited translation to game scenarios or coaching strategies. Similarly, a substantive percentage of studies (22%) did provide any practical applications, and where these were provided, they were generally broad and provided limited actionable information that could be used directly by practitioners to inform training. Where specific applications were provided these were consistent with a dynamic systems perspective of collective behaviour and focused on organismic, environmental and task constraints that could be manipulated. The findings of the present review highlight the innovative practices of the research base and identify several areas for development to increase understanding and uptake in practice

Interpreting magnitude of change in strength and conditioning: effect size selection, threshold values and Bayesian updating.

The magnitude of change following strength and conditioning (S&C) training can be evaluated comparing effect sizes to threshold values. This study conducted a series of meta-analyses and compiled results to identify thresholds specific to S&C, and create prior distributions for Bayesian updating. Pre- and post-training data from S&C interventions were translated into standardised mean difference (SMDpre) and percentage improvement (%Improve) effect sizes. Four-level Bayesian hierarchical meta-analysis models were conducted to compare effect sizes, develop prior distributions, and estimate 0.25-, 0.5-, and 0.75-quantiles to determine small, medium, and large thresholds respectively. Data from 643 studies comprising 6574 effect sizes were included in the analyses. Large differences in distributions for both SMDpre and %Improve were identified across outcome domains (strength, power, jump and sprint performance), with analyses of the tails of the distributions indicating potential large overestimations of SMDpre values. Future evaluations of S&C training will be improved using Bayesian approaches featuring the information and priors developed in this study. To facilitate an uptake of Bayesian methods within S&C, an easily accessible tool employing intuitive Bayesian updating was created. It is recommended that the tool and specific thresholds be used instead of isolated effect size calculations and Cohen's generic values when evaluating S&C training

The effects of creatine supplementation combined with resistance training on regional measures of muscle hypertrophy: a systematic review with meta-analysis.

The purpose of this paper was to carry out a systematic review with meta-analysis of randomized controlled trials that examined the combined effects of resistance training (RT) and creatine supplementation on regional changes in muscle mass with direct imaging measures of hypertrophy. Moreover, we performed regression analyses to determine the potential influence of covariates. We included trials of at least 6 weeks in duration that examined the combined effects of creatine supplementation and RT on site-specific direct measures of hypertrophy (magnetic resonance imaging [MRI], computed tomography [CT] or ultrasound) in healthy adults. A total of 44 outcomes were analyzed across 10 studies that met inclusion criteria. Univariate analysis of all standardized outcomes showed a pooled mean estimate of 0.11 (95% Credible Interval [CrI]: -0.02 to 0.25) providing evidence of a very small effect favoring creatine supplementation when combined with RT, compared to RT and placebo. Multivariate analyses found similar small benefits for the combination of creatine supplementation and RT on changes in upper and lower body muscle thickness (0.10-0.16 cm). Analyses of moderating effects indicated a small superior benefit for creatine supplementation on younger compared to older adults (0.17 [95% CrI: -0.09 to 0.45]). In conclusion, results suggest that creatine supplementation combined with RT promotes a small increase in direct measures of skeletal muscle hypertrophy in both the upper and lower body

Exploring the perceptions and experiences of community rehabilitation for long COVID from the perspectives of Scottish General Practitioners and people living with long COVID: a qualitative study.

The objective of this study was to explore the experience of accessing Long COVID community rehabilitation from the perspectives of people with Long COVID and General Practitioners (GPs). This was a qualitative descriptive study, employing one-to-one semi-structured virtual interviews that were analysed using the framework method. The study focused on four NHS Scotland territorial health boards. Participants included eleven people with Long COVID (1 male, 10 female; aged 40-65 [mean 53]), and 13 GPs (5 male, 8 female). Four key themes were identified: i) The lived experience of Long COVID; ii) The challenges of an emergent and complex chronic condition; iii) Systemic challenges for Long COVID service delivery, and iv) Perceptions and experiences of Long COVID and its management, including rehabilitation. The study concluded that there are several patient, GP, and service-level barriers to accessing community rehabilitation for Long COVID. There is a need for greater understanding by the public, GPs, and other potential referrers of the role of community rehabilitation professionals in the management of Long COVID. There is also a need for community rehabilitation services to be well promoted and accessible to the people with Long COVID for whom they may be appropriate. Service providers need to consider availability and accessibility of Long COVID rehabilitation and ensure adequate interprofessional communication and collaboration to enhance the experience for people with Long COVID

Exercise therapy for tendinopathy: a mixed-methods evidence synthesis exploring feasibility, acceptability and effectiveness.

Tendons are cords of strong, flexible tissue that attach muscles to bones, allowing joints to move. Tendinopathy is a common condition that can affect any tendon in the body, causing pain and limiting function. Exercise is often used to treat tendinopathy. We examined over 500 research papers on exercise for tendinopathy. The most common tendons to be studied were the calf (Achilles), knee (patellar), elbow, and shoulder. Strengthening exercise was studied most often, especially in lower limb tendinopathy. Other types of exercise such as stretching, balance and aerobic activity were less common, but were used to some extent in the upper and lower limbs. We found that exercise therapy is safe and beneficial for the tendinopathies that have been studied to date. Exercise may be most beneficial when combined with another intervention such as injection or electrotherapy. Strengthening exercise may be most beneficial for lower limb tendinopathies. However, more research is needed on the type of strengthening and the dosage, such as how many exercises and how much resistance to use. Shoulder tendinopathies may benefit from exercise that targets joint flexibility and position more than strengthening. We also found that people who receive exercise therapy for tendinopathy are generally satisfied with the effect it has on their symptoms. Finally, we found that an individualised, person-centred approach to delivering exercise therapy is valued by people with tendinopathy. They also believe that the patient-healthcare provider relationship is important for promoting the confidence and motivation people need to continue with exercise programmes, especially when they complete them independently. Although we examined a lot of papers, many of the studies were low quality. This means there is still a need for high-quality studies to tell us how effective specific types of exercise are for specific tendinopathies. There is also a need for more studies on patients' and professionals' experiences of receiving or providing exercise for tendinopathy.This project is registered as www.osf.io/a8ewy/ (scoping review); PROSPERO CRD 42020168187 (efficacy reviews); https://osf.io/preprints/sportrxiv/y7sk6/ (efficacy review 1); https://osf.io/preprints/sportrxiv/eyxgk/ (efficacy review 2); https://osf.io/preprints/sportrxiv/mx5pv/ (efficacy review 3); PROSPERO CRD42020164641 (mixed method review)