OpenUCT :: Browsing by Department "MRC/UCT RU for Exercise and Sport Medicine"

Browsing by Department "MRC/UCT RU for Exercise and Sport Medicine"

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Open Access
A 12 week pre-season fitnes training programme for senior male high school rugby players : the effect of supervision on anthropometric, physiological and physical performance variables
(1998) Clark, David Rodney; Lambert, Michael I
The study comprises of two sections; i) a survey to determine the attitude towards fitness training for rugby and the current fitness training habits of elite high school rugby players in their penultimate year at school, ii) a training study on a sample of the same population group, to measure the effect of a 12 week fitness training programme, based on scientific principles, on anthropometric, physiological and performance variables. The training study also measured the efficacy of training supervision compared no supervision on these variables.
Open Access
A comparison of indices of glucose metabolism in five black populations: data from modeling the epidemiologic transition study (METS)
(2015-09-15) Atiase, Yacoba; Farni, Kathryn; Plange-Rhule, Jacob; Luke, Amy; Bovet, Pascal; Forrester, Terrence G; Lambert, Vicki; Levitt, Naomi S; Kliethermes, Stephanie; Cao, Guichan; Durazo-Arvizu, Ramon A; Cooper, Richard S; Dugas, Lara R
Background: Globally, Africans and African Americans experience a disproportionate burden of type 2 diabetes, compared to other race and ethnic groups. The aim of the study was to examine the association of plasma glucose with indices of glucose metabolism in young adults of African origin from 5 different countries. Methods: We identified participants from the Modeling the Epidemiologic Transition Study, an international study of weight change and cardiovascular disease (CVD) risk in five populations of African origin: USA (US), Jamaica, Ghana, South Africa, and Seychelles. For the current study, we included 667 participants (34.8 ± 6.3 years), with measures of plasma glucose, insulin, leptin, and adiponectin, as well as moderate and vigorous physical activity (MVPA, minutes/day [min/day]), daily sedentary time (min/day), anthropometrics, and body composition. Results: Among the 282 men, body mass index (BMI) ranged from 22.1 to 29.6 kg/m2 in men and from 25.8 to 34.8 kg/m2 in 385 women. MVPA ranged from 26.2 to 47.1 min/day in men, and from 14.3 to 27.3 min/day in women and correlated with adiposity (BMI, waist size, and % body fat) only among US males after controlling for age. Plasma glucose ranged from 4.6 ± 0.8 mmol/L in the South African men to 5.8 mmol/L US men, while the overall prevalence for diabetes was very low, except in the US men and women (6.7 and 12 %, respectively). Using multivariate linear regression, glucose was associated with BMI, age, sex, smoking hypertension, daily sedentary time but not daily MVPA. Conclusion: Obesity, metabolic risk, and other potential determinants vary significantly between populations at differing stages of the epidemiologic transition, requiring tailored public health policies to address local population characteristics.
Open Access
A mixed ecologic-cohort comparison of physical activity & weight among young adults from five populations of African origin
(2014-04-24) Luke, Amy; Bovet, Pascal; Plange-Rhule, Jacob; Forrester, Terrence E; Lambert, Estelle V; Schoeller, Dale A; Dugas, Lara R; Durazo-Arvizu, Ramon A; Shoham, David A; Cao, Guichan; Brage, Soren; Ekelund, Ulf; Cooper, Richard S
Abstract Background Examination of patterns and intensity of physical activity (PA) across cultures where obesity prevalence varies widely provides insight into one aspect of the ongoing epidemiologic transition. The primary hypothesis being addressed is whether low levels of PA are associated with excess weight and adiposity. Methods We recruited young adults from five countries (500 per country, 2500 total, ages 25–45 years), spanning the range of obesity prevalence. Men and women were recruited from a suburb of Chicago, Illinois, USA; urban Jamaica; rural Ghana; peri-urban South Africa; and the Seychelles. PA was measured using accelerometry and expressed as minutes per day of moderate-to-vigorous activity or sedentary behavior. Results Obesity (BMI ≥ 30) prevalence ranged from 1.4% (Ghanaian men) to 63.8% (US women). South African men were the most active, followed by Ghanaian men. Relatively small differences were observed across sites among women; however, women in Ghana accumulated the most activity. Within site-gender sub-groups, the correlation of activity with BMI and other measures of adiposity was inconsistent; the combined correlation across sites was -0.17 for men and -0.11 for women. In the ecological analysis time spent in moderate-to-vigorous activity was inversely associated with BMI (r = -0.71). Conclusion These analyses suggest that persons with greater adiposity tend to engage in less PA, although the associations are weak and the direction of causality cannot be inferred because measurements are cross-sectional. Longitudinal data will be required to elucidate direction of association.
Open Access
A model for presenting accelerometer paradata in large studies: ISCOLE
(2015-04-20) Tudor-Locke, Catrine; Mire, Emily F; Dentro, Kara N; Barreira, Tiago V; Schuna, John M; Zhao, Pei; Tremblay, Mark S; Standage, Martyn; Sarmiento, Olga L; Onywera, Vincent; Olds, Tim; Matsudo, Victor; Maia, José; Maher, Carol; Lambert, Estelle V; Kurpad, Anura; Kuriyan, Rebecca; Hu, Gang; Fogelholm, Mikael; Chaput, Jean-Philippe; Church, Timothy S; Katzmarzyk, Peter T
Abstract Background We present a model for reporting accelerometer paradata (process-related data produced from survey administration) collected in the International Study of Childhood Obesity Lifestyle and the Environment (ISCOLE), a multi-national investigation of >7000 children (averaging 10.5 years of age) sampled from 12 different developed and developing countries and five continents. Methods ISCOLE employed a 24-hr waist worn 7-day protocol using the ActiGraph GT3X+. Checklists, flow charts, and systematic data queries documented accelerometer paradata from enrollment to data collection and treatment. Paradata included counts of consented and eligible participants, accelerometers distributed for initial and additional monitoring (site specific decisions in the face of initial monitoring failure), inadequate data (e.g., lost/malfunction, insufficient wear time), and averages for waking wear time, valid days of data, participants with valid data (≥4 valid days of data, including 1 weekend day), and minutes with implausibly high values (≥20,000 activity counts/min). Results Of 7806 consented participants, 7372 were deemed eligible to participate, 7314 accelerometers were distributed for initial monitoring and another 106 for additional monitoring. 414 accelerometer data files were inadequate (primarily due to insufficient wear time). Only 29 accelerometers were lost during the implementation of ISCOLE worldwide. The final locked data file consisted of 6553 participant files (90.0% relative to number of participants who completed monitoring) with valid waking wear time, averaging 6.5 valid days and 888.4 minutes/day (14.8 hours). We documented 4762 minutes with implausibly high activity count values from 695 unique participants (9.4% of eligible participants and <0.01% of all minutes). Conclusions Detailed accelerometer paradata is useful for standardizing communication, facilitating study management, improving the representative qualities of surveys, tracking study endpoint attainment, comparing studies, and ultimately anticipating and controlling costs. Trial registration ClinicalTrials.gov: NCT01722500
Open Access
A novel approach to enhance ACL injury prevention programs
(Springer Berlin Heidelberg, 2018-06-18) Gokeler, Alli; Seil, Romain; Kerkhoffs, Gino; Verhagen, Evert
Abstract Efficacy studies have demonstrated decreased anterior cruciate ligament (ACL) injury rates for athletes participating in injury prevention programs. Typically, ACL injury prevention programs entail a combination of plyometrics, strength training, agility and balance exercises. Unfortunately, improvements of movement patterns are not sustained over time. The reason may be related to the type of instructions given during training. Encouraging athletes to consciously control knee movements during exercises may not be optimal for the acquisition of complex motor skills as needed in complex sports environments. In the motor learning domain, these types of instructions are defined as an internal attentional focus. An internal focus, on one’s own movements results in a more conscious type of control that may hamper motor learning. It has been established in numerous studies that an external focus of attention facilitates motor learning more effectively due to the utilization of automatic motor control. Subsequently, the athlete has more recourses available to anticipate on situations on the field and take appropriate feed forward directed actions. The purpose of this manuscript was to present methods to optimize motor skill acquisition of athletes and elaborate on athletes’ behavior.
Open Access
A practical guide to the use of nutritional supplements in South Africa
(2004) Meltzer, Shelly; Kohler, Ryan; Jakoet, Ismail; Noakes, Tim D
Sportspersons should ensure that the decision to use a dietary supplement is a safe one. Unlike medicines, which are regulated by the Medicines Control Council, there is no governing body to control and regulate the supplement industry in South Africa. As a result many supplements may contain banned substances and there is a chance that not all the ingredients are accurately listed on the label of a supplement product. National and international sporting bodies place the responsibility of using supplements on the sportsperson. The legal clause ‘strict liability’ means that the sportsperson is responsible for any and all substances appearing in their urine and blood.
Open Access
Accuracy of reporting food energy intake: Influence of ethnicity and body weight status in South African women
(2010) Mchiza, Z J; Goedecke, Julia; Lambert, Estelle
The current study sought to identify characteristics that may be associated with the misreporting of food energy intake (EI) in urban South African women. A total of 198 women (61 black, 76 of mixed ancestry, 61 white) completed a quantified food frequency questionnaire, from which daily energy and macronutrient intake were calculated. Body composition (body mass index [BMI], percentage of body fat), body image (Feel-Ideal Difference index and Body Shape questions) and socio-economic status (SES) (household density and asset index) were also measured. Food EI in relation to estimated basal metabolic rate ratio that was less than 1.05 represented under-reporting, whereas a ratio greater than 2.28 represented over-reporting. Results suggested that 26% of the participants under-reported, 64% adequately reported and 10% over-reported. Participants who under-reported had a higher BMI (p < 0.01) and higher percentage of body fat (p < 0.05) than those who adequately and over-reported. The majority of under-reporters were black (38%) versus 21% under-reporters of mixed ancestry and 20% white under-reporters (p < 0.01). Eighty-three per cent of black under-reporters were obese. On the other hand, a majority (63%) of overweight women of mixed ancestry and a majority (50%) of white normal-weight women under-reported their food EI. Under-reporters reported a lower intake of dietary fat (p < 0.01) and a higher intake of dietary protein (p < 0.01) than adequate or over-reporters. Food EI reporting was not influenced by SES or body image. In conclusion, results suggest that food EI reporting is influenced by body size, and may be ethnic-specific in South African women.
Open Access
Accuracy of the prediction of Ironman performance : relationship to training history, muscle pain and relative perception of effort during, and recovery after the race
(2010) Spijkerman, Ronel; Lambert, Mike; Burgess, Theresa
With regards to swimming, cycling and running, several studies have investigated the physiological and genetic contribution of performance in athletes, different training programs and athletes' adaptation to these programs. Other studies have investigated levels of pain and relative perception of effort (RPE) and the athlete's ability to recover after endurance races... The aim of this thesis is to review the literture which discusses the background to the questions outlined above (Chapter 2), followed by a study which attempts to answer these questions (Chapter 3). The aim of the study was to establish whether the training methods in preparation for the Ironman were related to subjective pain and perception of effort during the race, and the recovery time after the race. The study was designed to establish whether there were differences in these variables between triathletes who predicted their finishing time accurately compared to those triathletes wo under-or over-predicted their performance.
Open Access
Achilles tendon ultrasound findings in triathletes before and after the ironman triathlon
(2006) Schwabe, Karen; Schwellnus, Martin
The aim of this prospective cohort study therefoew was to assess the morphological and blood flow changes in the Achille tendons of triathletes competing in the 2006 South African Ironman Triathlon.
Open Access
Age-related decrements in cycling and running performance
(2004) St Clair Gibson, A; Lambert, M I; Noakes, T D
Objective. This study examined age-related decrements in athletic performance during running and cycling activities. Design. The age group winning times for males aged between 18 and 70 years competing in the 1999 Argus cycle tour (103 km) and 1999 Comrades running marathon (90 km), South Africa's premier endurance cycling and running events respectively, were examined. Main outcome measures. The relationship between speed (cycling and running respectively) and age was calculated using a 4th order polynomial function. The derivative of each of these functions was determined and then the slope of the function corresponding to each age was calculated. Results. The rate of decline in running speed occurred at an earlier age (~ 32 years) during the running race compared with the cycling tour (~ 55 years). Conclusions. These findings establish a trend that there is ‘accelerated' aging during running which can perhaps be attributed to the increased weight-bearing stress on the muscles during running compared with cycling.
Open Access
Application of Intervention Mapping to develop a community-based health promotion pre-pregnancy intervention for adolescent girls in rural South Africa: Project Ntshembo (Hope)
(2014-06-20) Draper, Catherine E; Micklesfield, Lisa K; Kahn, Kathleen; Tollman, Stephen M; Pettifor, John M; Dunger, David B; Norris, Shane A
Abstract Background South Africa (SA) is undergoing multiple transitions with an increasing burden of non-communicable diseases and high levels of overweight and obesity in adolescent girls and women. Adolescence is key to addressing trans-generational risk and a window of opportunity to intervene and positively impact on individuals’ health trajectories into adulthood. Using Intervention Mapping (IM), this paper describes the development of the Ntshembo intervention, which is intended to improve the health and well-being of adolescent girls in order to limit the inter-generational transfer of risk of metabolic disease, in particular diabetes risk. Methods This paper describes the application of the first four steps of IM. Evidence is provided to support the selection of four key behavioural objectives: viz. to eat a healthy, balanced diet, increase physical activity, reduce sedentary behaviour, and promote reproductive health. Appropriate behaviour change techniques are suggested and a theoretical framework outlining components of relevant behaviour change theories is presented. It is proposed that the Ntshembo intervention will be community-based, including specialist adolescent community health workers who will deliver a complex intervention comprising of individual, peer, family and community mobilisation components. Conclusions The Ntshembo intervention is novel, both in SA and globally, as it is: (1) based on strong evidence, extensive formative work and best practice from evaluated interventions; (2) combines theory with evidence to inform intervention components; (3) includes multiple domains of influence (community through to the individual); (4) focuses on an at-risk target group; and (5) embeds within existing and planned health service priorities in SA.
Open Access
Are point-of-decision prompts in a sports sciece and medicine centre effective in changing the prevalence of stair usage? A preliminary study
(2009) Pillay, Julian D; Kolbe-Alexander, Tracy; Achmat, Masturah; Carstene, Madelaine; Lambert, Estelle V
Objective. To determine the impact of a signed intervention on promoting stair versus lift usage in a health and fitness facility. Design. A 3-week observational study in which a simple timeseries design of collecting data before, during and after the introduction of an intervention was used. Setting. The Sports Science Institute of South Africa (SSISA): a 5-storey building with a centrally located lift lobby and internal stairwell. Method. Observers were placed unobtrusively on the ground floor, with good visibility of lift/stairwell, to observe ascending movement of students, staff, tenants, visitors and patients 4 hours/day (07h00 - 09h00, 16h00 - 18h00), 4 days/week for 3 weeks. During week 2, motivational signs were displayed on the wall next to the lift and stairs and on the floor leading to the stairwell. In week 3, signage was removed. Factors considered in predicting stair use were gender, phase of intervention, and whether persons were staff/students or visitors. Results. A total of 4 256 person-counts were recorded. Prevalence of stair use increased from 43% before the intervention to 53% during the intervention to 50% after the intervention. Odds of using the stairs during the intervention increased by 45% (odds ratio (OR) 1.45, 95% confidence interval (CI) 1.25 - 1.68) (p<0.00001), were 41% higher for staff/students compared with visitors (p<0.00001) and were 55% greater for women (p<0.00001). These effects did not change significantly after the intervention and stair use remained modestly higher than before the intervention. Conclusion. Signed intervention produced significant increases in stair usage during and after the intervention. These findings support the effectiveness of point-of-decision prompts for changing behaviour, and highlight potential factors influencing the impact of such messages.
Open Access
An assessment of muscle insertion sites and biomechanical beam analaysis in living subjects
(2001) Sanders, Virginia M; Morris, Alan G; Louw, Graham J; Constant, Deborah A
The main aim of this study is to examine the gross morphology of the radial tuberosity, brachialis insertion site and supinator crest in living subjects, and to correlate this with muscle strength.
Open Access
The association between cardiorespiratory fitness and performance in a submaximal stepping test standardised for external workload
(2016) Huchu, Linet; Lambert, Michael I
Submaximal step tests are used to predict maximal oxygen consumption and work capacity. However, if the external workload is not controlled the interpretation of the test results may be inaccurate. The purpose of the research was to develop a submaximal test of cardiorespiratory fitness using a novel step test designed specifically to overcome the weaknesses of the previously published step tests. A series of studies contributed to the theoretical development of the submaximal step protocol, piloting the protocol, reliability studies, validation of the protocol and finally a cross-validation of the protocol. The first study tested the hypothesis that stepping tests configured for the same external workload, but varying in stepping frequency, elicit the same physiological stress. Participants (n = 31) performed three step tests at 16, 20 and 24 steps per minutes in random order. External workload was standardised at 45 kJ. Energy expenditure, heart rate recovery, rating of perceived exertion, maximum heart rate and total heart beats were significantly different between tests (p < 0.05) with the biggest differences occurring between 16 and 24 steps per minute. Maximum heart rate as a percentage of age predicted heart rate increased from 70% at 16 steps per minute to 81% at 24 steps per minute. The study concluded that standardisation of external workload with different exercise intensities does not result in the same physiological responses. The second study tested the reliability of the step test. Participants (n = 34) performed a step test three times in a week at a cadence of their choice (16, 20 or 24 steps per minute). The study showed that the step test is repeatable for most variables measured and therefore is a reliable test of fitness. The third study used the outcome variables measured during the step test to develop equations which predicted VO₂max measured directly in a maximal test on a treadmill. A diverse sample of participants (n = 273), differing in sex, level of habitual physical activity and age were recruited for the study. Several models for predicting VO₂max were determined. The most parsimonious equation was: VO₂max (ml.kg⁻¹.min⁻¹) = -0.10911 (age) - 0.06178 (body mass) - 0.75481 (body fat %) +0.00208 (METS) + 0.11636 (HRR) - 0.019551 (MHR) + 0.07955 (Av HR) + 83.34846 (R² = 0.75, standard error of estimate = 5.51 ml.kg.min⁻¹) where METS is metabolic equivalent, HRR is heart rate recovery, MHR is maximum heart rate and Av HR is average heart rate. Cross validation was done (n = 50) to test the accuracy of the prediction equation. The relationship between the predicted VO₂max and the measured VO₂max was r = 0.87. In conclusion the standardised step test can predict VO₂max in a heterogeneous population of males and females, varied ages (20 to 60 years), physical activity levels and fitness levels.
Open Access
The association between daily steps and health, and the mediating role of body composition: a pedometer-based, cross-sectional study in an employed South African population
(BioMed Central, 2015-02-22) Pillay, Julian D; van der Ploeg, Hidde P; Kolbe-Alexander, Tracy L; Proper, Karin I; van Stralen, Maartje; Tomaz, Simone A; van Mechelen, Willem; Lambert, Estelle V
Background: Walking is recognized as an easily accessible mode of physical activity and is therefore supported as a strategy to promote health and well-being. To complement walking, pedometers have been identified as a useful tool for monitoring ambulatory physical activity, typically measuring total steps/day. There is, however, little information concerning dose-response for health outcomes in relation to intensity or duration of sustained steps. We aimed to examine this relationship, along with factors that mediate it, among employed adults. Methods: A convenience sample, recruited from work-site health risk screening (N = 312, 37 ± 9 yrs), wore a pedometer for at least three consecutive days. Steps were classified as “aerobic” (≥100 steps/minute and ≥10 consecutive minutes) or “non-aerobic” (<100 steps/minute and/or <10 consecutive minutes). The data were sub-grouped according to intensity-based categories i.e. “no aerobic activity”, “low aerobic activity” (1-20 minutes/day of aerobic activity) and “high aerobic activity” (≥21 minutes/day of aerobic activity), with the latter used as a proxy for current PA guidelines (150-minutes of moderate-intensity PA per week). Health outcomes included blood pressure, body mass index, percentage body fat, waist circumference, blood cholesterol and blood glucose. Analysis of covariance, adjusting for age, gender and total steps/day were used to compare groups according to volume and intensity-based steps categories. A further analysis compared the mediation effect of body fat estimates (percentage body fat, body mass index and waist circumference) on the association between steps and health outcomes, independently. Results: Average steps/day were 6,574 ± 3,541; total steps/day were inversely associated with most health outcomes in the expected direction (p < 0.05). The “no aerobic activity” group was significantly different from the “low aerobic activity” and “high aerobic activity” in percentage body fat and diastolic blood pressure only (P < 0.05). Percentage body fat emerged as the strongest mediator of the relationship between steps and outcomes, while body mass index showed the least mediation effect. Conclusion: The study provides a presentation of cross-sectional pedometer data that relate to a combination of intensity and volume-based steps/day and its relationship to current guidelines. The integration of volume, intensity and duration of ambulatory physical activity in pedometer-based messages is of emerging relevance.
Open Access
The association between exercise-induced muscle damage and cortical activity in the alpha and beta frequency range
(2011) Plattner, Kristina; Lambert, Michael I; Baumeister, Jochen
This thesis examines the regulation of muscle function following exercise-induced muscle damage (EIMD), in an attempt to determine whether regulation occurs primarily in the muscle (neuromuscular) or further upstream. Upstream regulation has been hypothesized to occur in the lower brain structures, but one may assume that the efferent output to the muscle should be guided by the motor and pre-motor cortex alongside other associated cortical areas.
Open Access
Association between smoking and total energy expenditure in a multi-country study
(2014-10-04) Gonseth, Semira; Dugas, Lara; Viswanathan, Barathi; Forrester, Terrence; Lambert, Vicki; Plange-Rhule, Jacob; Durazo-Arvizu, Ramon; Luke, Amy; Schoeller, Dale A; Bovet, Pascal
Abstract Background The association between smoking and total energy expenditure (TEE) is still controversial. We examined this association in a multi-country study where TEE was measured in a subset of participants by the doubly labeled water (DLW) method, the gold standard for this measurement. Methods This study includes 236 participants from five different African origin populations who underwent DLW measurements and had complete data on the main covariates of interest. Self-reported smoking status was categorized as either light (<7 cig/day) or high (≥7 cig/day). Lean body mass was assessed by deuterium dilution and physical activity (PA) by accelerometry. Results The prevalence of smoking was 55% in men and 16% in women with a median of 6.5 cigarettes/day. There was a trend toward lower BMI in smokers than non-smokers (not statistically significant). TEE was strongly correlated with fat-free mass (men: 0.70; women: 0.79) and with body weight (0.59 in both sexes). Using linear regression and adjusting for body weight, study site, age, PA, alcohol intake and occupation, TEE was larger in high smokers than in never smokers among men (difference of 298 kcal/day, p = 0.045) but not among women (162 kcal/day, p = 0.170). The association became slightly weaker in men (254 kcal/day, p = 0.058) and disappeared in women (−76 kcal/day, p = 0.380) when adjusting for fat-free mass instead of body weight. Conclusion There was an association between smoking and TEE among men. However, the lack of an association among women, which may be partly related to the small number of smoking women, also suggests a role of unaccounted confounding factors.
Open Access
The association of the AVPR2 gene with serum sodium and water imbalances during an Ironman Triathlon
(2007) Ah Kun, Maresa; Collins, Malcolm
It is well documented that participation in ultra-endurance events such as the Ironman Triathlon, can be associated with the development of post-race water and sodium imbalances in athletes. Variants within genes that encode for proteins that regulate thirst have been shown to be associated with weight changes during participation in an Ironman Triathlon. Recent evidence of mutations within the arginine vasopressin 2 receptor (AVPR2) gene, which encodes a constitutively active receptor in the collecting tubules of the kidney, resulted in increased water reabsorption and hyponatraemia in two unrelated male infants. This suggests that serum imbalances and hydration status in individuals participating in an endurance event may also be, in part, controlled by variants withink the AVPR2 gene. The aim of this study was to investigate whether polymorphisms within the AVPR2 gene are associated with exercise-associated serum sodium and/or water imbalances in triathletes who particpated in the 2006 South African Ironman Triathlon.
Open Access
The batting backlift technique in cricket
(2017) Noorbhai, Mohammed Habib; Noakes, Timothy
The batting technique in cricket consists of various elements such as the grip, stance, backlift, downswing, impact with the ball and follow through. Whilst there has been an extensive amount of research into these batting elements, there is little research specifically on the backlift technique. Therefore, we aimed to investigate and provide a scientific understanding of the batting backlift technique (BBT) in cricket. We aimed to investigate the BBT of the most successful batsmen (n = 65) in the last 120 years as well as players in the Indian Premier League (IPL) (n = 30). It was found that these batsmen did not conform to the current cricket coaching method that advocates a straight batting backlift technique (SBBT). Instead, 77% of successful batsmen and 90% of IPL batsmen employed a lateral batting backlift technique (LBBT) in which they lifted their bats in the direction of second slip or beyond with the bat face towards the off-side. Using this technique, both the toe of the bat and face of the bat points directly towards the off-side (usually between slips and point). The number of players using the LBBT was significantly greater than those using the SBBT (χ2 = 19.2, df = 1, p < 0.001). Given these findings, we were curious to determine whether this finding was similar at other levels of cricket. The second study therefore employed biomechanical and video analyses to evaluate the BBT of current semi-professional, professional and international cricketers (n = 155) from South Africa and the United Kingdom. The backlift of these batsmen was then compared to their career statistics. It was found that a LBBT is more prevalent at the highest levels of the professional game and a likely contributor factor for successful batting at the highest level (p≤0.05). The LBBT was also found to positively affect other components of the batting technique such as the stance and scoring areas. We then proceeded to investigate the BBT amongst the lower levels of cricket (junior and adolescent cricketers). The third study consists of an intervention study that employed a biomechanical analysis of coached and uncoached cricketers (n = 80). It was found that more than 70% of uncoached cricketers adopted a LBBT, whereas more than 70% of coached cricketers adopted the SBBT. Having found that the LBBT is a likely contributing factor for past and current successful batsmen, it was then important to understand what BBT the current cricket coaches are teaching at various proficiency levels. The fourth study explored the teachings of the BBT among international cricket coaches (n = 161) using a mixed methods approach through an online evaluation survey. This study was able to show that a majority of cricket coaches teach what is advocated in coaching manuals and mostly coach the SBBT as opposed to the LBBT at various levels of the game. In the fifth and sixth studies, this thesis further describes two innovative coaching tools that can improve and assist with the coaching of the LBBT. Firstly, a novel coaching cricket bat was investigated through a pilot and intervention study. In the pilot group, cricketers using the coaching bat scored approximately 1 more run per ball or an average of approximately three more runs in total when using the coaching bat than the normal bat (F = 6.70, df = 1, p = 0.012). In the intervention study, the experimental group scored double the total number of runs (an additional 16 runs) and an average of approximately 3 more runs per player in the post-match than in the pre-match, which showed a large effect (ES = 5.41) (t = 3.32, df = 5, p = 0.021). The coaching cricket bat might be used to coach young cricket players to hit the ball more effectively as well as how to adopt a more LBBT. Secondly, a mobile application was developed, which can be used by players, coaches and scientists to analyse and improve the BBT among cricketers at all levels. In summary, this thesis has shown that the LBBT is a likely contributing factor to successful batsmanship at all levels of cricket ability (junior cricketers, adolescent cricketers, semi-professional cricketers, professional cricketers, international cricketers and former elite/successful cricketers). Coaching a LBBT to young batsman may be challenging and therefore a coaching cricket bat has been developed and has shown to be a promising training aid for coaching the LBBT to young cricketers. A mobile application has also been designed and tested to assist in the coaching of the BBT in cricket. A way forward for further research in this area of cricket batting is documented at the end of the thesis.
Open Access
Beyond the VO2max plateau a new approach for measuring maximal oxygen uptake
(2013) Beltrami, Fernando Gabe; Noakes, Tim; Wagner, Peter D
Maximal oxygen consumption (VO2max) is typically defined by the presence of the "plateau phenomenon" during incremental exercise tests, in which O2 consumption levels-off in spite of increases in workload. This is thought to reflect a limitation in the capacity of the heart to pump O2 enriched blood to the exercising limbs. Some researchers however question not only the biological validity of the "plateau concept", based on mathematical and methodological issues, but whether O2 delivery to the exercising muscles indeed sets the upper limits for VO2max. This thesis aimed to address some of these controversies.