OpenUCT :: Browsing by Author "Derman, Wayne"

Browsing by Author "Derman, Wayne"

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Open Access
Body composition and physical performance characteristics of elite senior and U19 South African rugby union players
(2000) Scales, Nicola; Derman, Wayne; Lambert, Mike
Bibliography: leaves 126-134.
Open Access
Clinical and imaging features of the lumbar spine in elite male schoolboy cricketers : the effect of a pre-season lumbar stabilisation intervention
(2008) Aginsky, Kerith Dana; Derman, Wayne; Gray, J
Current evidence indicates that schoolboy cricketers are at a high risk of injury to the lumbar spine. This is particularly relevant in the case of fast bowlers who bowl with a high degree of shoulder counter-rotation. There, however, is a lack of evidence in the literature with respect to injury research of all cricketing disciplines, as fast bowlers receive the most attention. After reviewing the literature it was evident that the effect of a cricket-specific lumbar stabilisation exercise intervention in an attempt to reduce lower back pain and alter other physiological variables, had never been studied. Previous interventions in cricketers have focused only on fast bowlers in an attempt to decrease the degree of shoulder counter-rotation. However, these studies either took two years to observe a decrease or were unsuccessful.
Open Access
Comparative effects of calcium channel antagonism and beta-1 selective blockade on exercise performance in physically active hypertensive patients
(1997) Selvey, Christine Enid; Derman, Wayne
The current recommendations by the American Heart Association for health promotion are that all persons should partake in regular physical activity in order to reduce the risk of cardiovascular disease. Regular physical exercise reduces blood pressure and is an important component of the management of hypertension. It is therefore important that patients with hypertension participate in habitual physical exercise. Many hypertensive patients who exercise will require anti-hypertensive medication. However, some antihypertensive agents cause fatigue during exercise. In order for patients to gain the full benefits of an active lifestyle, it is important that the prescribed antihypertensive agent does not prevent them performing and enjoying sustained exercise. It has been well documented that β-blockers cause premature fatigue during physical exercise. The effects on exercise performance of other first line antihypertensive medications, such as calcium channel antagonists have not been extensively investigated. In particular, the effects of these agents on prolonged submaximal exercise endurance have not been well studied. The object of this thesis was to compare the effects of isradipine, a dihydropyridine calcium channel antagonist, to those of atenolol, a β₁-selective antagonist, on maximal and submaximal exercise performance and on short duration high-intensity exercise in physically active hypertensive patients. The study design was a crossover trial where drug treatments were double blinded and randomised. Physically active volunteers with mild to moderate hypertension were recruited. 11 subjects performed i) progressive exercise to exhaustion for determination of maximal oxygen consumption (VO₂max), maximal work load and cardiorespiratory responses to maximal exercise, ii) prolonged submaximal exercise for determination of exercise endurance, cardiorespiratory responses and ratings of perceived exertion (APE), and iii) short duration, high intensity exercise consisting of a 30 second maximal exercise test (Wingate test) to determine skeletal muscle power output, following 4 weeks ingestion of isradipine (2.5mg bd), atenolol (50mg bd) or placebo. Diastolic blood pressure at rest was reduced by both atenolol and isradipine, but was lowered to a greater extent by atenolol (83.3 vs 89.0 vs 96.1 mmHg, atenolol vs isradipine vs placebo, p<.0005). Systolic blood pressure at rest tended to be similarly reduced by both agents, but was significantly reduced during maximal and submaximal exercise by atenolol only (p<.001, atenolol vs isradipine, placebo). Heart rate at rest and during maximal and submaximal exercise was decreased by atenolol only (p<.0005, atenolol vs isradipine, placebo). Maximal exercise performance was reduced after atenolol ingestion compared to placebo but not after isradipine ingestion. Peak workload achieved during the maximal exercise test was decreased after atenolol but unchanged after isradipine ingestion (214 vs 243 W, atenolol vs placebo, p<.01). Similarly, VO₂max was reduced after atenolol compared to placebo but was unchanged after isradipine ingestion (33.6 vs 36.4, 33.6 vs 36.1 mlO₂/kg/min, atenolol vs placebo, atenolol vs isradipine, p<.05). Both atenolol and isradipine ingestion reduced submaximal endurance time compared to placebo (27.8 vs 46.4, 34.4 vs 46.4 min, atenolol vs placebo, isradipine vs placebo, p<.005), and increased rating of perceived exertion (APE) after 30 min of submaximal exercise (p<.05). Submaximal oxygen consumption (VO₂), ventilation, respiratory exchange ratio (REA) and blood lactate, glucose and free fatty acid concentrations were not altered after the ingestion of either agent. Neither agent influenced peak skeletal muscle power, total work done, or rate of fatigue during the Wingate test compared to placebo. The results of these studies indicate that impaired performance and increased RPE during submaximal exercise after ingestion of either atenolol or isradipine is not due to alterations of ventilation, VO₂, RER, or blood lactate, glucose and free fatty acid concentrations during prolonged submaximal exercise. Similarly, reduced submaximal exercise performance after atenolol or isradipine ingestion is not due to factors which would also limit the ability of skeletal muscle to perform short duration, high intensity exercise before a bout of prolonged exercise. This study demonstrates that prolonged submaximal exercise testing can reveal an impairment in exercise performance after ingestion of antihypertensive medication which is not evident during maximal exercise testing. This finding is important as prolonged submaximal exercise is the form of exercise which most hypertensive patients actually perform. Further research is required on the effects of anti-hypertensive medications on submaximal exercise performance before firm recommendations can be made regarding medications most suitable for the physically active hypertensive patient. The results of these and other studies indicate that it is not yet possible to make claims that the calcium channel antagonist agents are without effect on physical exercise performance in physically active hypertensive patients.
Open Access
Critical analysis of techniques for normalising electromyographic data : from laboratory to clinical research
(2008) Albertus, Yumna; Lambert, Mike; Derman, Wayne; Tucker, Ross; Noakes, Tim
Measurements of muscle activity derived from surface EMG electrodes are variable due to both intrinsic and extrinsic factors. The intrinsic factors are endogenous in nature (features within the body) and include muscle fiber type, muscle fiber diameter and length, the amount of tissue between muscle and electrode, and depth and location of muscle with respect to the placement of electrodes (24). These biological factors vary between subjects and cannot be controlled. The extrinsic factors are experimental variables which are influenced by the researcher and can be controlled to some extent. Examples of extrinsic factors include the location, area, orientation, shape of electrodes and the distance between electrodes (interelectrode distance). In order to measure biological variation in the EMG signal, which is important in studies where surface EMG is used to gain understanding of physiological regulation, it is important to minimise the variation caused by these factors. This is in part achieved through the appropriate method of normalisation. The isometric maximal voluntary contraction (MVC) has been used as a standardmethod of normalisation for both static and dynamic exercises. However, researchers have recently improved the methods of normalisation by developing alternative techniques for the measurement of EMG during dynamic activities. By using the same type of movement for normalisation as during the trial, experimental errors can be reduced. The appropriate method of normalisation is defined as a method that is capable of showing repeatability, reliability (low intra-subject variation) and sensitivity to changes in EMG amplitude that is due to biological change and not the contribution of experimental factors. The aim of this thesis was to critically analyse alternative methods of EMG normalisation during dynamic exercise. The data should provide possible guidelines to researchers who are planning studies involving measurement of EMG activity during cycling, running and in clinical populations. Furthermore, the thesis aimed to illustrate that decisions regarding the most appropriate method of normalisation should be based on the study design, research question (absolute muscle activity or changes in muscle pattern) and the muscles being investigated.
Open Access
The effects of amlodipine on exercise performance in mild to moderate essential hypertensives
(1997) Gillies, Hunter Campbell; Derman, Wayne
The effect of the long acting dihydropyridine calcium channel antagonist, amlodipine, on the exercise performance of hypertensive patients is not known. The aim of this study was to determine the effects of amlodipine on maximal (MAX), prolonged submaximal (PSX) and on skeletal muscle function (SMF) in patients with mild hypertension. In a double-blind randomised crossover trial, ten physically active hypertensive patients performed i) graded exercise to exhaustion for determination of maximal oxygen consumption (VO₂ₘₐₓ), peak heart rate (HR) and systolic blood pressure (SBP); ii) PSX at 75% VO₂ₘₐₓ to determine, cardiorespiratory responses, cardiac output (Q), blood lactate [La], free fatty acid [FFA], glucose [G] concentrations and ratings of perceived exertion (RPE), and iii) tests of isometric SMF including maximal voluntary contraction (MVC) and time to fatigue (TTF) during repetitve isometric MVC's. Tests were performed following two week ingestion of amlodipine (5 mg daily) or placebo seperated by a two week washout period. Resting SBP was decreased following ingestion of amlodipine (142 ± 13 vs l33 ± 12 mmHg; vs placebo: [mean± SD]; P<0.05). However, VO₂ₘₐₓ ( 31 ± 5 vs 33 ± 5 mlO₂.kg.min⁻¹ ; amlodipine vs placebo), peak heart rate ( 167 ± 12 vs 165 ± l6b.min⁻¹;amlodipine vs placebo)and peak SBP(l8l ±21 vs 170± 16mmHg; amlodipine vs placebo) were not reduced following ingestion of amlodipine. Submaximal cycling time. VO₂, Q, BP, HR, ventilation, RPE, [FFA], [La] and [G] during PSX were unaltered following ingestion of amlodipine. Similarly ingestion of amlodipine did not alter tests of isometric SMF. These data suggest that: i) ingestion of amlodipine lowers resting SBP but does not alter the normal haemodynamic response during exercise; ii) MAX, PSX exercise performance and SMF are unaltered following ingestion of amlodipine in athletic hypertensive patients. These findings suggest that the regulatory mechanisms which maintain haemodynamic homeostasis during maximal and submaximal exercise are not influenced by ingestion of amlodipine in athletic hypertensive patients.
Open Access
The effects of an ultra-endurance event on heart rate variability and cognitive performance during induced stress in Ironman triathletes
(2009) Joubert, Ilse; Derman, Wayne
The effects of long-term participation in ultra-endurance exercise on the cardiovascular system have recently been the subject of much interest. It is well known that HRV, a marker of autonomic activity, is enhanced with long-term aerobic exercise training. However, after acute exercise, HRV is reduced, but recovers over time depending on the intensity of the prior bout of exercise. A limitation of previous research is that exercise bouts of only up to 120 minutes have been studied. A modified Stroop Task is a laboratory stressor to assess executive cognitive function by means of reaction time and accuracy. The resting HRV is directly related to these prefrontal neural functions, but the effect of an altered HRV on cognitive function has never been investigated. We determined the effects of an ultra duration (10 – 15 hours) exercise event on parameters of HRV and cognitive function during a Modified Stroop Task, 60 – 200 minutes after the 2007 South African Ironman Triathlon event (3,6km swim; 180 Km cycle; 42,2 Km run). 1 Female and 13 male competing triathletes (IRON; ages 33.7±7.9) and 7 control subjects (CON; 2 female and 5 males aged 42 ±4.5) completed a Modified Stroop Task before and after the event. The individual HRV parameters, heart rate (HR), respiratory frequency (RF), reaction time (RT) and % of mistakes made were recorded via the Biopac MP150WSW System (Goletta, California, USA). Data was transformed by auto regressive analyses (Biomedical signal analysis group, University of Kuopio, Finland) into LF (0.04 - 0.15 Hz) and HF (0.15 - 0.5 Hz) components. Additional calculations included %LF and %HF as well as the central or peak frequencies in both the LF and HF bands.
Open Access
Exercise tolerance and skeletal muscle structure and function in patients with chronic obstructive pulminary disease
(1998) Coleman, Kirsty Lee; Derman, Wayne
Exercise intolerance is well documented in patients with chronic obstructive pulmonary disease (COPD). Historically, this exercise intolerance has been attributed to the central factors of lung damage and subsequent heart failure. However, recent evidence suggests that (i) patients with cardiac and renal failure suffer from skeletal muscle (SM) abnormalities that impair exercise tolerance and (ii) patients with chronic obstructive pulmonary disease (COPD) may have metabolic and functional abnormalities of SM. However, no studies have conducted a detailed investigation of SM structure and function and their relation to exercise tolerance in patients with COPD.
Open Access
Exercise training in patients with peripheral vascular disease
(2003) Parr, Bridget Marianne; Derman, Wayne
Patients with peripheral vascular disease (PVD) suffer from the symptom of intermittent claudication and are walking intolerant. However, it is not clear what contributes to walking intolerance in patients with PVD.
Open Access
Illness and injuries in athletes with visual impairment at the London 2012 Paralympic Games
(2017) Stopforth, Louise; Derman, Wayne; Albertus, Yumna
Background: Participation in sport by athletes with impairment has grown and evolved rapidly since the inception of the Paralympic Games. Athletes with visual impairment were first included in the Paralympic Games in 1976. Surveillance of illnesses and injuries forms the first important step in determination of the epidemiology and an understanding of the risk factors for both illness and injuries in these populations. Thus, surveillance can therefore assist medical teams in implementing prevention strategies. Few studies have evaluated the incidence of illness and injuries amongst athletes with impairment. For this reason, a novel web based injury and illness surveillance system (WEBIISS) was developed for use by the team physicians at the London 2012 Paralympic Games. To our knowledge, no study has specifically researched the epidemiology of illness and injuries in athletes with visual impairment during a major sport event such as the Paralympic Games. Objective: To determine the incidence associated with illness and injuries in athletes with visual impairment during the London 2012 Paralympic Games. We further aim to describe any differences between sports, age groups, gender and body systems affected in this cohort of athletes. Methods: This study was a retrospective analysis of a component of the large prospective cohort study on the epidemiology of injury and illness conducted over a 14-day period at the London 2012 Paralympic Games. The data from 711 of the 791 athletes with visual impairment who participated in the London 2012 Paralympic Games were analyzed. The following data sources were used: Firstly, de-identified information regarding age, gender, impairment, country code and sports code of athletes obtained from the International Paralympic Committee database. Secondly, information collected from the electronic medical data capture system (EMDCS) used at all the London Organizing Committee for the Olympic and Paralympic Games (LOCOG) medical stations; and thirdly a novel web-based injury and illness surveillance system (WEB-IISS) used by the team physicians. This is the most comprehensive reporting system used in elite athletes with impairment to date. Data were collected on a daily basis from 3 days prior to the start of the Paralympic Games (pre-competition period) until the last day of the 11-day Paralympic Games (competition period). Definitions: In order to determine the nature and extent of illnesses and injuries as well to enable uniformity in research studies evaluating the data collected during the London 2012 Paralympic Games, the following definitions were implemented: Illness was defined as 'any newly acquired illness as well as exacerbation of pre-existing illness that occurred during training or competition, and during or immediately before the London 2012 Paralympic Games'. Injury was defined as 'any newly acquired injury as well as exacerbation of pre-existing injury that occurred during training and/or competition period of the London 2012 Paralympic Games'. Incidence rate (IR) of illness or injury is the number of illnesses or injuries per 1000 athlete days. Incidence proportion (IP) of illness or injury is the proportion of athletes affected by illness or injury (n/100). Results: Incidence rate of illness (IR 11.9; 95% CI 9.0 - 15.7) was similar to incidence rate of injuries (IR 14.5; 95% CI 11.3 - 18.5) in VI athletes. The IR of illness for VI athletes (IR 11.9; 95% CI 9.0 - 15.7) compared well to that of illness for all impairment groups (IR 12.7; 95% CI 10.2 - 16.0). Furthermore, the IR of injuries for VI athletes (IR 14.5; 95% CI 11.3 -18.5) compared well to that of injuries for al impairment groups (IR 12.6; 95% CI 10.3 - 15.4). Gender and age did not affect the risk of illness or injuries in VI athletes. Furthermore, there was a higher IR of illness for swimmers with visual impairment compared to other sports, but this was not statistically significant. The IR of illness for VI athletes participating in swimming was 12.5 (95% CI 8.8 - 17.8) compared to that of VI non-swimmers, IR 11.8 (95% CI 8.9 - 15.6). Participation in athletics (track and field) was associated with a slightly higher risk for injury for athletes with VI compared to other sports, but this was not statistically significant. The IR of injury was 15.8 (95% CI 11.6 - 21.5) and the IP 22.1 (95% CI 16.3 - 30.1) for VI track and field athletes. The IR of injury was 13.0 (95% CI 9.6 - 17.4) and IP 18.1 (95% CI 13.5 - 24.3) amongst VI athletes not participating in track and field athletics. VI swimmers had a lower IR of injury (IR 4.1; 95% CI 1.8 - 9.5) than VI non-swimmers (IR 16.1; 95% CI 12.6 - 20.7) (p=0.002). There was a higher IR and IP of lower limb injuries compared to upper limb injuries in athletes with visual impairment. The IR for lower limb injuries in athletes with visual impairment was 7.7 (95% CI 5.8 - 10.3) and the IP was 10.8 (95% CI 8.1 - 14.4). The average IR of lower limb injuries for all para-athletes was 4.5 (95% CI 3.5 - 5.7). The IR for upper limb injuries in athletes with visual impairment was 3.0 (95% CI 1.9 - 4.5) and the IP was 4.1 (95% CI 2.7 - 6.3). The average IR for upper limb injuries for all para-athletes was 4.5 (95% CI 3.5 - 5.9). Conclusion: The findings of this study suggest that Paralympic athletes with VI had a similar incidence rate of illness and injury compared to other impairment groups; and IR of illness was similar to that of injuries. Risk of illness or injury was not affected by age group or gender, but rather sport specific differences were observed. Of particular interest was the fact that athletes with VI had a higher incidence rate of lower limb injuries than upper limb injuries.
Open Access
Innovative spinal cord injury rehabilitation in the context of a middle-income country: a pilot randomised control study investigating physiological and psychological effects
(2021) Evans, Robert William; Albertus, Yumna; West, Sacha; Derman, Wayne
A spinal cord injury (SCI) is life-altering, resulting in neurological deficits and a multitude of secondary complications. South Africa holds one of the highest traumatic SCI incidence rates in the world, where the social need for SCI prevention and rehabilitation is immense. Robotic locomotor training (RLT) is a novel rehabilitation technique that may improve health and wellbeing after SCI. A systematic review was conducted across 27 studies and 308 participants to explore the systemic effects of RLT. This review demonstrated that RLT shows promise as a tool for improving neurological rehabilitation outcomes; providing individuals with a SCI the ability to walk safely while improving their walking performance, as well as potentially improving cardiovascular outcomes and psychosocial factors. However, the studies reviewed were non-controlled with small, heterogenous sample sizes. Further high-powered, randomised controlled trials, with homogenous samples, are required to investigate these effects. If widespread adoption of these new technologies is to occur, sound evidence demonstrating efficacy and long-term cost saving is required. This dissertation aimed to explore some of these under-researched areas in a sample of sixteen persons with incomplete tetraplegia. Areas of focus included, 1) rehabilitation feasibility, adherence, and research challenges in an under-resourced environment 2) cardiovascular functioning and adaptation to a rehabilitation programme, and 3) psychological well-being. We implemented two interventions, robotic locomotor training (RLT) and activity-based training (ABT), over a 24-week pilot randomised control trial. Adherence to the interventions was high (93.9 ± 6.2%). Challenges to the study's feasibility included: ethical approval, medical clearance, transport and limited human/financial resources. Cardiovascular parameters demonstrated that efficiency of exoskeleton walking improved during the intervention. RLT may be more effective than ABT in improving cardiac responses to orthostatic stress, with standing heart rate at 24-weeks being significantly lower in the RLT group (75.1 ± 15.0 beats/min) compared to the ABT group (95.6 ± 12.6 beats/min). Standing and RLT had similar effects on the parasympathetic nervous system, whilst both interventions were limited in their effect on brachial and ankle blood pressure. Despite experiencing past trauma, participants possessed psychological resources including resilience, self-efficacy and post-traumatic growth which contributed to high perceptions of quality of life. The use of an exoskeleton may have had a greater positive impact on subjective psychological well-being. Expectations of participants entering the study centred around regaining the ability to walk again, despite past experiences and medical advice suggesting otherwise. Hope aids in buffering against negative emotions, however, a thin line exists between supporting high expectations and confronting unrealistic hope. Initial high expectations of recovery decreased and became more realistic during the intervention. This dissertation demonstrates potential physiological and psychological benefits that RLT provides. Despite this potential, barriers exist in the use of RLT in low- and middle-income countries such as South Africa, primarily due to a lack of financial and human resources. The development of lower-cost exoskeletons would lessen the burden of conducting large-scale trials and increase the likelihood of adopting these innovative rehabilitation tools into current standard of care practices.
Open Access
Medical complications during a community-based mass participation endurance running event – an investigation of the epidemiology and risk factors associated with medical complications, with recommendations for risk mitigation
(2021) Schwabe, Karen; Schwellnus, Martin; Derman, Wayne; Bosch, Andrew
Background: The epidemiology and risk factors associated with medical complications, including life-threatening complications during distance running events has not been well described. The aims of this research were to document the incidence of medical complications (study 1), determine risk factors associated with medical complications (studies 2 and 3), and develop and apply a pre-race medical screening tool to determine the prevalence of chronic disease in race entrants, using a risk stratification model (study 4). Design: Prospective studies Setting: Two Oceans Marathon races (2008-2011) (studies 1-3) and race entrants (2012) Participants: Studies 1-3: 65 865 race starters; 21.1 km (n =39 511), 56 km runners (n=26 354). Study 4: 15 778 race entrants Methods: Study 1: In all 4 years, race day medical complications were recorded and subdivided by severity (serious life-threatening/death), organ system and final diagnosis. Studies 2 and 3: Independent risk factors associated with all medical complications, severity and organ system involvement were determined in 21.1 and 56km runners, using multivariate modeling. Study 4: A pre-race medical screening tool was developed, based on international pre-exercise medical screening guidelines, and administered to all race entrants (2012). The prevalence (%) of runners with four risk categories was determined. Results: The incidence (per 1000 race starters) of all and serious/life-threatening medical complications was 8.27 and 0.56 respectively (study 1). Risk factors associated with medical complications were less experience (56km), slower running pace (56 km) and older females (21.1 km) (studies 2 and 3). 16.8% runners were identified as those that should undergo medical evaluation for suspected cardiac disease with 3.4% reporting existing CVD (very high risk) and 13.4% reporting multiple CVD risk factors (high risk) (study 4). Conclusion: The incidence of all and serious/life-threatening medical complications in the 21.1km and 56km race is 1/121 and 1/1786 race starters respectively. Race experience, running pace and sex are risk factors for medical complications. 16.8% runners have underlying suspected cardiovascular disease. These data formed the basis for the implementation of a pre-race medical screening and risk stratification. The research lays the foundation for a future educational intervention programme to reduce the risk of medical complications in distance running and other endurance events.
Open Access
Medical consequences following endurance sports : acute pre-race illness : the effect of a screening and educational intervention program on race participation, inability to finish a race and medical complications during a race
(2015) Van Tonder, Anri; Schwellnus, Martin; Derman, Wayne
The main objectives of this dissertation was: 1) to review the available evidence with respect to the period prevalence of pre-race upper respiratory tract infections (the week before a distance running event) in distance runners, the relationship between exercise and infections, and the possible health consequences of participating in sport whilst suffering from an acute infective illness; 2) to document the period prevalence of runners with an acute illness in the 7-day period prior to an endurance race; 3) to determine the period prevalence of runners who "fail" the "neck check", and would be advised not to participate in the race, 4) to determine the incidence of runners with an acute illness, and who received educational information and guidelines, and who then not start the race, 5) to determine the incidence of runners with an acute illness who chose to start the race, but do not finish the race, and 6) to determine the incidence of runners with an acute illness who chose to start the race, but develop medical complications during the race.
Open Access
Performance and fatigue charateristics of paralympic athletes with cerebral palsy
(2015) Runciman, Phoebe Anne; Derman, Wayne; Tucker, Ross; Ferreira, Suzanne; Albertus-Kajee, Yumna
The studies described in this thesis were the first to investigate in - depth body composition, exercise performance and neuromuscular characteristics of elite Paralympic athletes with cerebral palsy (CP). In the first study, in - depth whole body and site specific body composition was investigated in six athletes with CP using dual - energy x - ray absorptiometry. There were no differences between non - affected and affected sides with respect to bone mineral density and fat mass. Fat free soft tissue mass was lower on the affected side in bot h upper and lower limbs of the athletes. The novel findings of this study provided the first insight into anthropometric and bone physiology of elite Paralympic athletes with CP, and the possible residual effect of CP in these individuals. In the second study, five athletes with CP and 16 able - bodied (AB) age and performance matched controls performed a 30 second Wingate sprint cycle test. Power output was significantly higher in the AB group, although fatigue indices were statistically similar between groups. Muscle activity changed similarly in all muscle groups tested, in both affected and non - affected sides, in both CP and AB groups. However, certain neuromuscular irregularities were identified in the CP group. The similarity in fatigue profile was a novel finding. It was proposed that this similarity in fatigue was the result of long term high level athletic training required for Paralympic competition. Study three tested the similarity in fatigue between CP and AB athletes (that was described in the second study), using an externally paced fatiguing running trial. Six athletes with CP and 12 AB athletes performed one 40 m sprint test and vertical jump tests off both legs, the affected leg individually and the non - affected leg individually, before and after an adapted multistage shuttle run test to exhaustion. The 40 m sprint test, vertical jump off both legs and vertical jump off the affected leg were significantly compromised in the CP group, while vertical jump off the non - affected leg was similar between groups. Both groups fatigued similarly with regard to performance and muscle activity. The third study's finding s generally supported those of the second study. However, it was shown that although athletes with CP may represent a group of individuals who have achieved maximal physiological adaptation toward AB levels, the activity generated by both legs was performed towards the capacity of the affected leg. Study four attempted to elucidate explanations for the novel findings in studies 2 and 3 through investigation of pacing strategies employed by these athletes. Six athletes with CP and 13 AB athletes performed two trials of eight sets of ten shuttles (totalling 1600 m). One trial was distance deceived and the other was non distance deceived. The CP group ran slower than the AB group in both trials, and differences in pacing were observed in the deceived trial in the CP group. This novel study provided evidence for a possible pacing strategy underlying the exercise performance and fatigue profiles observed in the athletes with CP documented in the previous studies. The work described in this thesis lends novel insights and understanding to the physiology and physiological adaptations of highly functioning ambulant athletes with CP. The findings might have important implications with respect to the understanding of rehabilitation, coaching and clinical management of individuals with CP.
Open Access
Physiological effects of heart rate variability biofeedback during laboratory induced congnitive stress
(2012) Prinsloo, Gabriell Elizabeth; Derman, Wayne
Heart rate variability (HRV) biofeedback is effective in reducing stress as well as managing chronic disease. It facilitates easy manipulation of HRV, and, therefore, potentially provides a valuable intervention for altering the activity of the autonomic nervous system. The aim of this thesis was to examine the effects of a single 10 minute episode of HRV biofeedback on measures of HRV and EEG during and immediately after the intervention, measures of HRV and cognitive performance during laboratory induced cognitive stress and subjective feelings of anxiety and relaxation states after testing. Eighteen healthy male volunteers (34 ± 6 years) exposed to work-related stress, were randomised into an HRV biofeedback intervention (BIO) and a comparative intervention group (COM).
Open Access
Physiological evaluation of sleep surfaces in healthy volunteers and patients with acute-upon-chronic lower back pain
(1998) Hulse, Bronwyn Leigh; Derman, Wayne
Studies have documented that the use of a lumbar support while in the sitting position results in reduced back and leg pain, centralisation of pain and reduced erector spinae muscle activity in patients with lower back pain (LBP). While the positive effects of a lumbar support in sitting have been studied, few researchers have attempted to document the value of such a support in the supine position. Since many patients with LBP suffer from insomnia and nocturnal discomfort, it may be possible that the use of a foam surface overlay could positively influence their symptoms. Several foam surface overlays are currently used as a popular form of management for patients presenting with LBP. These include the convoluted foam surface ("egg box'' shape), which to my knowledge has not been scientifically studied and the lumbar body support, the value of which has only recently been reported. That study found that patients with chronic LBP have decreased electromyographic (EMG) activity of the erector spinae muscles, lower heart rates (HR) and decreased perception of discomfort (ROD) when lying on this locally designed, triple density, contoured, lumbar body support system (LBS) compared with a conventional flat innerspring mattress (CM). Accordingly the aim of this thesis was to measure the EMG activity, heart rate response, perception of comfort and pattern of pressure distribution after lying on a variety of different surfaces, thus endeavouring to determine a mechanism of action of the LBS. In the first study of this thesis, ten patients with LBP were exposed to a random order, 30 minute period on three sleep surfaces: Lumbar body support on top of a conventional mattress (LBS+ CM), 60 mm convoluted foam surface on top of a conventional mattress (CFS + CM), and a conventional mattress (CM) alone. Each patient acted as his/her own control. Recordings of EMG activity, HR and ROD were measured for each patient. Average HR over the 30 minute period was lower after acute exposure to the LBS+ CM (60 ± 11 b/min) compared to the CM (66 ± 10 b/min, p < 0.05; LBS+ CM vs. CM). Although average HR response to the LBS+ CM was lower compared to CFS + CM (64 ± 9 b/min), this difference was not significant. ROD reported after acute exposure to the LBS+ CM was improved (1.9 ± 0.7 units), compared to the CFS+ CM (3.9 ± 1.0 units) and CM (4.7 ± 2.2 units; p < 0.05). Average EMG activity was lower after 30 minutes on the LBS + CM (2.68 ± 1.1 mv) compared to the CFS+ CM (4.46 ± 2.7 mv) and CM (4.19 ± 2.4 mv; p < 0.05). These results suggest that patients with LBP have reduced EMG activity and HR measurements with lower ROD when lying on a LBS + CM compared with a CM and CFS + CM. The second series of experiments involved a further ten patients with lower back pain, who were required to lie supine in random order on the LBS + CM, on a polystyrene mould (PM) (identical to the shape of the LBS) and on a CM. Recordings of EMG activity, HR and ROD were measured for each patient. Average HR over the 30 minute period was lower on the LBS + CM (60 ± 7 b/min) vs. PM + CM (66 ± 10 b/min) and CM (68 ± 9 b/min; p < 0.01 ). Average ROD was improved when patients lay on the LBS+ CM (1.8 ± 0.6 units) vs. PM + CM (5. 7 ± 2.5 units) and CM (4.1 ± 1.8 units; p < 0.05). Furthermore, average EMG activity was significantly reduced after lying on the LBS + CM (2.5 ± 1.0 mv) vs. PM + CM (4.3 ± 1.9 mv) and CM (4.6 ± 1.8 mv; p < 0.01 ). The findings of this study mirror our initial findings. The elevated EMG activity, heart rate and perception of discomfort after lying on a PM suggests that it could be a combination of both the correct density and the correct contour features that is important in reducing muscle spasm in patients with acute-upon-chronic lower back pain. Average HR over the 30 minute period was lower after acute exposure to the LBS+ CM (60 ± 11 b/min) compared to the CM (66 ± 10 b/min, p < 0.05; LBS+ CM vs. CM). Although average HR response to the LBS+ CM was lower compared to CFS + CM (64 ± 9 b/min), this difference was not significant. ROD reported after acute exposure to the LBS+ CM was improved (1.9 ± 0.7 units), compared to the CFS+ CM (3.9 ± 1.0 units) and CM (4.7 ± 2.2 units; p < 0.05). Average EMG activity was lower after 30 minutes on the LBS + CM (2.68 ± 1.1 mv) compared to the CFS+ CM (4.46 ± 2.7 mv) and CM (4.19 ± 2.4 mv; p < 0.05). These results suggest that patients with LBP have reduced EMG activity and HR measurements with lower ROD when lying on a LBS + CM compared with a CM and CFS + CM. The second series of experiments involved a further ten patients with lower back pain, who were required to lie supine in random order on the LBS + CM, on a polystyrene mould (PM) (identical to the shape of the LBS) and on a CM. Recordings of EMG activity, HR and ROD were measured for each patient. Average HR over the 30 minute period was lower on the LBS + CM (60 ± 7 b/min) vs. PM + CM (66 ± 10 b/min) and CM (68 ± 9 b/min; p < 0.01 ). Average ROD was improved when patients lay on the LBS+ CM (1.8 ± 0.6 units) vs. PM + CM (5. 7 ± 2.5 units) and CM (4.1 ± 1.8 units; p < 0.05). Furthermore, average EMG activity was significantly reduced after lying on the LBS + CM (2.5 ± 1.0 mv) vs. PM + CM (4.3 ± 1.9 mv) and CM (4.6 ± 1.8 mv; p < 0.01 ). The findings of this study mirror our initial findings. The elevated EMG activity, heart rate and perception of discomfort after lying on a PM suggests that it could be a combination of both the correct density and the correct contour features that is important in reducing muscle spasm in patients with acute-upon-chronic lower back pain. body support is altered and pressures are more equally distributed when compared to the pressure distribution of the other surfaces measured, without increases in pressure at any point on the body. Similar average and peak pressure results were obtained for the 90 mm CFS + CM and LBS. Since these results were not mirrored by the 60 mm CFS, the thickness of a foam surface possibly plays a role in reducing pressure. The data of these three separate studies could have implications in the adjunctive treatment of i)low back pain and ii) pressure sores. Firstly, the results of this thesis suggest that the use of a 60 mm foam overlay may not be the optimum form of management for patients presenting with paraspinal muscular spasm. Further, it is postulated, that the density and contour features of the lumbar body support are likely to play a role in reducing EMG activity and heart rate, while improving perception of comfort compared to the flat surfaces (CM and 60 mm CFS), which offer little support to the lumbar region of these patients. X Secondly, either the LBS or 90 mm CFS are likely to reduce the incidence of pressure sores in patients required to lie supine for prolonged periods, due to the reduction in peak and average pressures. In view of the contoured surface, it is unlikely that pressure sores could develop in patients lying on the LBS. This hypothesis needs to be confirmed in longer term studies in patients who are severely debilitated or paraplegic, as they are often most at risk for the development of pressure sores.
Open Access
Profiles of illness and injury among South African elite athletes with disability at the 2012 Summer Paralympic Games
(2016) Constantinou, Demitri; Albertus, Yumna; Derman, Wayne
Epidemiological data is important to better understand injury and illness patterns in para athletes. Medical teams used a web-based injury and illness surveillance system (WEB-IISS system) to all the para-athlete injuries and illnesses during the 2012 London Paralympic games. All team physicians could access the system at any time to log data, providing a vast database for potential research. The relative ease of data collection permits large amounts of data to be analysed, providing important surveillance data on injury and illness. Data on the South African para-athletes, provided by the team's Chief Medical Officer, were assessed and compared to all countries. This study aimed to describe the illness and injury profiles in South African elite paraathletes who participated in the 2012 Summer Paralympic Games; and compare these profiles to data from the other countries that participated. A retrospective sub-analysis of the data-set collected from a large prospective study of injury and illness at the London Summer Paralympic Games in 2012 was compared to data collected on all para-athletes from input by team physicians into the WEB-ISS system. In total, 62 South African para-athletes presented with 19 injuries, with an injury rate of 21.9 per 1000 athlete days. Twenty-five para-athletes presented illness, with an illness rate of 28.8 per 1000 athlete days. The overall injury and illness rate in the South African para-athletes was higher than the injury and illness rate in all para-athlete participants at the London Paralympic Games. The anatomical distribution of injuries (lower limbs, axial and upper limbs) and the nature of illness (respiratory, skin & subcutaneous and digestive systems) were however similar. Causative factors are not evident and need to be further studied. Increased efforts in injury and illness surveillance and preventative programmes should be employed to reduce the incidence of injury and illness, and their severity . Such efforts in para-athlete care should be ongoing with surveillance to monitor and manage trends to ensure the culmination of Paralympic competition does not result in high rates of injury and illness. Education of healthcare providers, para-athletes, coaches and others in the management of para-athletes, is key.
Open Access
Psychological correlates of injury, illness and performance in Ironman triathletes
(2008) Hugo, Daniel; Derman, Wayne; Collins, Malcolm
Background: The association of psychological factors with athletic performance and proneness to injury and illness has been widely recognised as an integral part of athletic preparation, treatment and rehabilitation. The exact nature of this association is still not clear, but it can be hypothesised that better mental health leads to better performance, less injuries and illness and more rapid recovery. Psychological distress is a strong predictor of injury, illness and poor performance, but inherent personality traits have failed to show a constant association with these parameters. Advances in validated psychometric instruments of personality and resilience show promise in their application to further the understanding of the psyche in athletes. Objective: The aim of this study was to evaluate the predictive value of personality traits (novelty seeking, harm avoidance and reward dependence), resilience and general psychological distress in terms of injury, illness and performance in a group of triathletes competing in the 2007 lronman Triathlon. Methods: For this descriptive cross-sectional study, 166 entrants in the 2007 lronman Triathlon were recruited. Each subject completed a detailed, previously validated set of questionnaires during registration prior to the event. Contained in the questionnaire were sections on general demographic information, detailed previous and current medical conditions and injuries, and psychometric instruments (TPQ - a measure of personality, CD-RISC - a measure of resilience, K10). After the event, the official overall finishing times, as well as the split times for the swimming, cycling and running legs, were obtained from the race organisers. Results: Higher NS and RD scores were predictors for faster predicted performance times and higher psychological distress scores was a predictor for slower actual times (r=0.160, P=0.053) and particularly predicted slower cycling times (r=0.026, P=0.002). Higher K10 scores significantly predicted the presence of flu-like symptoms (P=0.019) and higher HA scores significantly predicted nervous system symptoms during exercise (P=0.035). Higher RD scores predicted the absence of nervous system symptoms (P=0.075). Higher K10 scores (P=0.093) and HA scores (P=0.070) were associated with medication use prior to and during the event. Higher resilience scores predicted the occurrence of exercise associated collapse (P=0.081) and absence of EAMC (P=0.075). Higher HA scores predicted GIT symptoms during exercise (P=0.091 ). Higher reward dependence predicted the presence of tendon / ligament injuries (P=0.039) and genital injuries were associated with lower resilience (P=0.098) and higher HA scores (P=0.065). Conclusion: Generally, the results showed only a few consistent findings in terms of identifying predictors, although interesting correlations and trends were observed. Studies on different athletic populations and on a larger scale are needed. Physicians should be aware of the cardinal importance of mental well-being, as this is as vital in the preventative and curative management of the injured, ill or poor performing athlete as optimal physical conditioning.
Open Access
Psychological correlates of performance, injury and illness in Two Oceans Ultramarathon athletes
(2014) Baba, Sachin Ramanlali; Derman, Wayne; Collins, Malcolm
Background: It is well accepted that psychological factors play an important role in athletic performance, illness and injury. Yet, few studies have investigated the effects of psychological factors on performance, illness and injury in endurance athletes. While general psychological traits of athletes and the non-athletic population has been described in the past, the specific relationship between psychological factors and their effects on performance in ultra-marathon athletes has not been fully described. Further, unlike their influence in the general population, the influence these psychological factors may have on the onset of injury and illnesses in an athletics population is not as well known. The availability of psychometric instruments that have shown potential when applied specifically to athletic population is promising for application in this area of research. Objective: The aim of this study was to describe the relationship between the psychological factors (personality traits, resilience and general psychological distress scores) and athletic performance and susceptibility to injuries and illnesses prior to the race in a cohort of ultra-marathon runners participating in the 2009 Two Oceans 56 km road ultra-marathon.
Open Access
Respiratory health of the endurance athlete : prevalence of respiratory related conditions/illnesses in endurance athletes
(2011) Cloete, Carolette; Schwellnus, Martin; Derman, Wayne
Background: Endurance athletes, in particular triathletes and ultra-distance runners, undergo high volumes of intense training in preparation for events. There is recent epidemiological evidence that the respiratory tract is the most common system affected by illness in athletes during tournaments. Respiratory tract symptoms have also been shown to affect endurance athletes particularly in the post- event period. However, the prevalence of respiratory related illnesses including respiratory tract symptoms, asthma, and allergies in the pre-race period has not been well studied in endurance athletes. Objective: The main aims of this dissertation were 1) to review the existing literature focussing on the epidemiology, pathogenesis, possible aetiology and management of respiratory tract symptoms, asthma and allergies in athletes, and 2) to conduct an investigation to determine the pre-event period prevalence (6 weeks and 1 week before an event) and nature of respiratory tract symptoms, asthma and allergies in Ironman triathletes and ultra-distance runners. Methods: In the first part of the dissertation, a review of the literature pertaining to respiratory tract symptoms and illness was undertaken. In the second part of the dissertation, a cross-sectional descriptive study was undertaken in 441 triathletes entering the 2006 and 2007 Ironman Triathlon, and 152 ultra- distance runners in the 2009 Two Oceans Ultra-marathon. In the 1 to 3 days before the race (registration period), participants were requested to complete a validated pre-event medical questionnaire containing sections on demographics, training and previous competition, common medical conditions and detailed sections on respiratory symptoms in the 6 weeks and 1 week period before the race, as well as asthma and allergies experienced. Respiratory symptoms were divided into upper respiratory tract symptoms (URTS), lower respiratory tract symptoms (LRTS) and systemic symptoms (SS). All data obtained regarding these respiratory related illnesses were compared between the triathlete group and the ultra- distance runners. Results: The main findings in the experimental section of the dissertation were that 1) triathletes trained significantly more hours in the 6 weeks and 1 week before an event than ultra-distance runners, 2) the period prevalence (6 weeks before the race) of respiratory tract symptoms was 50% of triathletes and 35% of ultra-distance runners, 3) upper respiratory tract symptoms and particularly nasal symptoms (nasal congestion and rhinorrhoea) were significantly more common in triathletes (21 to 27%) in comparison with ultra-distance runners (12 to 17%), 4) systemic symptoms (especially pyrexia) were significantly more common in ultra-distance runners in the 1 week before an event (9.2 vs. 2.4%), 5) the point prevalence of self-reported asthma was low in both study groups (ultra-distance runners 3.4% and triathletes 8.3%) although symptoms of dry cough, wheezing, shortness of breath and "tight" chest were reported by 25 to 80% of athletes in both study populations, 6) in most cases the diagnosis of asthma was made by means of history taking and a physical examination by a physician, 7) majority of triathletes used beta 2-agonists only as the treatment of choice for asthma symptoms, while ultra-distance runners used combinations of corticosteroids and beta 2-agonist inhalers as first line treatment, 8) allergies were reported by 34% of triathletes and 22.3% of ultra-distance runners, 9) most allergic symptoms in both study groups were confined to the upper respiratory tract with hay fever ranging from 77 to 83% and sinusitis 55 to 64.2%, and 10) the most common medication used for allergies by triathletes and ultra- distance runners, were anti-histamine tablets. Conclusion: There is a high period prevalence of respiratory symptoms in triathletes and ultra-distance runners in the 6 weeks before an endurance event. Triathletes had a significantly higher prevalence of upper respiratory tract symptoms (especially nasal symptoms) in comparison to ultra-distance runners, which might be related to allergies and a higher training volume. There also appears to be a lack in proper diagnostic evaluation of asthma in these endurance athletes with suboptimal and improper treatment of asthma and allergies. Approximately 10% of ultra-distance runners had systemic symptoms in the week before the event, indicating a lack of athlete education on possible risks of exercising with a systemic illness.
Open Access
The seasonal and lifetime incidence of low back pain in South African male first league squash players
(1996) Burden, Stephen Barry; Hawley, John; Derman, Wayne
Previous studies have been conducted to determine the incidence of low back pain (LBP) in both the general population as well as in participants of different sporting activities. The purpose of this study was to determine the seasonal and lifetime incidence of LBP in male first league squash players.