Browsing by Author "McKune, Andrew James."

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Association between physical fitness and job performance in South African fire-fighters.
(2012) Schmidt, Carl.; McKune, Andrew James.
Aim. Accurate correlations between a wide range of physical fitness measures and occupational demands are needed in order to identify specific fitness tests and training needs for firefighters. Methods. Forty-eight experienced, professional firefighters (29 ± 7.24 yrs) participated in fitness and job performance testing sessions each spaced a week apart. Analysis was performed using Pearson moment correlation coefficients and multiple linear regression with alpha set at p≤.05. Results. Significant correlations (p≤.01) were found between a job performance task (Revised Grinder) and the following: lean muscle mass (r = -.69), overall fitness (r = -.62), height (r = -.62), strength endurance: deadlift (r = -.54), bent-over row (r = -.51), bench press (r = -.51), shoulder press (r = -.46); maximal strength: hand grip strength (r = -.57), bench press (r = -.51), anaerobic capacity: 400m (r = .50), and aerobic capacity: multistage shuttle run (r = -.46). Multiple linear regression determined that lean muscle mass and aerobic capacity account for 82% of the variation in the job performance task. Conclusion. It is apparent that firefighting taxes virtually all aspects of physical fitness. This data can help the exercise specialist choose appropriate tests and prescribe specific fitness programmes for firefighters. Traditional firefighter exercise programmes focusing mainly on cardiovascular fitness should be replaced with physical conditioning programmes that address all components of fitness. Cardiovascular fitness testing should include the performance of job-related tasks to improve test validity.
Diet and supplementation practice in professional Ethiopian football players : effects on performance and recovery.
(2018) Masho, Tesfaye Berhane.; McKune, Andrew James.; Van Heerden, Jaques Johan.
The game of football places high physiological demands on players, who are expected to react by carrying out a range of physical activities at different intensities. Such movement patterns contribute to a high energy turnover in both training and match-play, which in turn must be sustained by the intake of adequate fuel sources. In this thesis, three studies were undertaken with the intention of gaining greater insight into, and adding to the body of knowledge of, football nutrition in Ethiopia. The studies included an evaluation of the impact of a sports nutrition education programme on the dietary, sports nutrition and supplement practices of the Ethiopian national football squad during the period 2012 to 2014 (Study 1). The dietary intake, sports nutrition and supplementation practices of professional Ethiopian football players currently playing in Ethiopian Premier League clubs (Study 2) were then studied, as well as the relationships between training load, energy balance, performance and recovery (Study 3). Study – 1. Football players require adequate knowledge of nutrition to allow correct selection and consumption of food and fluids to meet their performance, body composition and overall health needs. The aim of this study was to examine the effect of a sports nutrition intervention on the nutrition knowledge and dietary choices of the players who were members of the Ethiopian national football squad between 2012 and 2014. The following sports nutrition topics were discussed: timing of nutrition, recovery, hydration, post exercise physiological perceptions, macronutrients, sports drinks, fruit and vegetables, alcohol and its impact on performance. Participants attended nutrition education sessions for six months, each one 20 to 30 minutes in duration. Interview and focus group discussions were administered to 20 Ethiopian national squad players and the head and two assistant coaches working with them. The data were analysed using manual coding matrices. The analysis of the interview data revealed that all the national team players exhibited significant knowledge of football nutrition after the nutrition education intervention. The intervention helped them to adhere to proper dietary and recovery procedures, and also significantly helped the players understand dietary CHOs as a vital source of fuel for football which as a result benefited them to change their misconception they had about CHO before the intervention. Some players had believed, at the beginning of the intervention, that alcohol had an ergogenic effect. In conclusion, this study revealed that nutrition education for professional football players can have positive results. The education programme must be entertaining and should not be too long. Based on these findings, was concluded that football players in Ethiopia would benefit from nutrition education targeting an improvement in nutrition knowledge and dietary practices. Key words: Ethiopian national squad football players, dietary practices, Nutrition education, nutrition knowledge. Study – 2. Similarly, to other professional football players, Ethiopian players require appropriate nutritional intake because of the physiological demands of the game. To understand the dietary practices and nutrition plans of these players, a dietary assessment of current Ethiopian professional players was conducted. The aim of this study was to assess the dietary intake of 126 players age M = 27.3, ±SD = 3.0 years), weight M = 72.4, ±SD = 7.0 kg, height M = 1.77, ±SD = .06 m, BMI M = 23.1, ±SD = 1.6 kg.m2 from seven Ethiopian premier league football clubs; during a competitive week, over a four-day period. Food was weighed and means (standard deviation) and 95% confidence limits were calculated and compared across clubs using one-way analysis of variance followed by Bonferroni post-hoc testing. There were significant differences in dietary macronutrient composition across the teams in the four study periods, the dietary intake in g/day and in g/kg of body weight for CHO on Thursday was significantly different M = 344.6, ± SD = 12.5, p = 0.030, g/day compared with Monday’s dietary CHO intake, in g/day and in g/kg of body weight, M = 308.3, ± SD = 96.4 g/day. The study revealed a dietary CHO intake was below the recommendation of 500-600 g/day. With great significant difference among clubs ranging from M = 459.9, ± SD = 104.1, p < 0.001. g/day to M = 256.0, ± SD = 58.5, p < 0.001 The mean dietary CHO, compositions in g/kg of body weight, across the teams were significantly different ranging from, 3.6 (.9) g/kg of body weight to 6.1 (1.3) g/kg of body weight.; In conclusion, the results show that the nutritional intake of the players was not optimal unlike protein and fat the mean daily CHO intake of Ethiopian professional football players was lower than recommended. These findings may have both short- and long-term negative consequences on the performance and recovery as well as health of the players. On the basis of our results, we recommended that nutritional education should be given to the players at an early age and should continue throughout adolescence. Key words: Ethiopian premier league, Dietary macronutrient intake, dietary assessment. Study – 3. It is important that football training load, which includes functional testing, is closely linked with optimal energy intake. This enhances performance and recovery process between training sessions. The aim of this study was to investigate the associations between dietary practice and performance and recovery of twenty professional Ethiopian football players from the same team (M = 23.8, ± SD = 3.3 years). During an intense seven-day, (Monday to Sunday) pre-season training period, food was weighed and recorded, and total and macronutrient energy intake was determined, and energy expenditure calculated. Performance testing (Yo-Yo Intermittent Recovery Test Level 1 (YYIR1) was also performed pre- and post the seven-day period. Data were expressed as the mean (standard deviation). A one-way ANOVA, with Bonferroni posthock testing, paired t-tests, Pearson correlation, and multiple regression were used in the statistical analysis. The mean dietary intake for protein was significantly higher in terms of daily intake in grams and per kilogram of body weight across the seven days ranging from M = 257, ± SD = 44, p < 0.001 g/day, to M = 168, ± SD = 24, p < 0.001, g/day. And M = 3.6, ± SD = .7, p < 0.001 g/kg of body weight to M = 2.3, ± SD = .4, p < 0.001 g/kg of body weight. Overall, our results show that the nutritional intake of the players was not optimal and resulted in a high mean daily energy deficit of M = -144.8, ± SD = 1111.7 calories was observed between the energy intake of M = 3765.1, ± SD = 1104.7 calories and the energy expenditure of M = 3909.9, ± SD = 191.2 calories. The study revealed that dietary fat was the highest source of energy, which is not the preferred fuel for football players. The mean distance covered post the seven days of training for the YYIR1 significantly decreased by 25% (pre: M = 2266 ± SD = 526 m versus post: M = 1666 ± SD = 456 m). This result represented a 10% decrease in VO2max values among the study participants from session 1 pre: M = 55.4 ± SD = 4.4 ml/kg/min versus post: M = 50.4 ± SD = 3.8 ml/kg/min. In summary, the YYIRT1 result may have been related to the energy deficit of the players over the seven days of pre-season training. In addition, players consumed higher levels of dietary fat and low levels of CHO during intense training, which is not the recommended for optimal performance and recovery in professional football players Key words: Preseason training, YYIRT1, energy balance and training load. In conclusion, the studies included in this thesis found that 1) elite Ethiopian football players benefitted from a sports nutrition education intervention, 2) there is a disparity in macronutrient composition across football teams participating in the Ethiopian Premier League and 3) energy deficit during a week of intense preseason training is associated with reduced performance and recovery of players.
The effects of a structured group exercise program on functional fitness of older persons living in old age homes within the eThekwini Municipality, South Africa.
(2014) Chetty, Levin.; Ramklass, Serela Samita.; McKune, Andrew James.
Aim: The study aimed to determine the effects of a structured group exercise program on functional fitness of older persons living in five old age homes within the eThekwini Municipality of South Africa. Population: The study population comprised men and women aged 60 years and older, who reside in an old age home within the eThekwini Municipality. Design: A quasi-experimental design was used to compare the effect of a 12 week group exercise program on two groups of participants using pre-test post-test procedures. Methodology: Twenty participants each were selected from five old age homes. Participants were randomly allocated into either an experimental group or a comparison group at each site. The experimental group participated in the exercise intervention three times weekly for 12 weeks, while the comparison group received the same intervention twice weekly for 12 weeks. The prescribed intervention was guided by the recommendations outlined by the American College of Sports Medicine (ACSM) and American Heart Association (AHA) respectively. It comprised of warm-up, balance, endurance, resistance and cool-down components. Assessments of upper and lower body strength and flexibility, aerobic endurance, agility and balance were conducted before and after the intervention using the Senior Functional Fitness Test. Data was analysed using Microsoft Excel 2013 and Statistical Package for Social Sciences version 20.1. Results: Comparisons of baseline and post-intervention measures showed greater improvements in upper and lower body strength and flexibility, as well as aerobic endurance capacity (p < 0.05). But, no improvements were observed in participant’s agility and balance levels. With regards to training frequency, no significant difference in functional fitness measures was observed between both groups following the 12 week intervention program. Conclusion: Twelve weeks of multifaceted group exercise training, at least two times per week can be used as an effective strategy to promote functional fitness in the elderly population.
Effects of group exercise on salivary biomarkers of mucosal immunity and hypothalamic-pituitary adrenal axis activation in older persons living in aged care facilities.
(2015) Dudhrajh, Prathna Abhimun.; McKune, Andrew James.; Ramklass, Serela Samita.
Abstract available in PDF file.
Effects of high or moderate intensity training on inflammation and endothelial function in insulin resistance.
(2019) Thaane, Tshidi.; McKune, Andrew James.; Motala, Ayesha Ahmed.
Exercise training improves insulin resistance (IR) via numerous mechanisms including improved endothelial function and reduced systemic inflammation. However, it is unclear whether high intensity interval training (HIIT) offers superior benefit when compared with continuous moderate intensity training (CMIT) in a clinical population. This thesis reports findings from a clinical trial designed to determine the effects of short-term high or moderate intensity training on inflammation and endothelial function in overweight/obese adults with IR. Furthermore, the thesis provides a report on factors associated with IR in this population. Clinical examinations (body composition), blood tests [serum insulin and serum C-reactive protein (CRP), plasma glucose] and physiological tests (microvascular function and aerobic fitness tests) were undertaken on consenting individuals who volunteered to participate in the study. Study participants were stratified into IR and insulin sensitive (IS) groups based on their homeostatic model assessment (HOMA-IR) scores. The IR and IS groups were each further randomized into control (CNT), HIIT or CMIT sub-groups. The HIIT and CMIT sub-groups underwent baseline measures and exercise training for 10 consecutive days, followed by a repeat of baseline measures. The CNT sub-group was tested at baseline and post follow-up without taking part in the exercise intervention. When compared with CMIT, HIIT produced a greater improvement in markers of IR [(HOMA-IR); 32% vs. 9% by CMIT] and endothelial function [(PORHmax and MV); 37.59% and 27.45%, respectively, vs. 8.24% and -25.71%, respectively, by CMIT]. These improvements occurred without changes in body fat or aerobic fitness. Cohen’s (d) effect sizes indicated that the improvements produced by HIIT were large, while those of CMIT were unclear, suggesting that HIIT may be the ideal mode of training when the primary goal is to improve IR and endothelial function in overweight/obese adults. Cross-sectional analysis of baseline data indicated that the acute-phase inflammatory protein, CRP, was strongly associated with IR in black Africans. However, this association was only significant in males. Suggesting that CRP has potential clinical application as a maker of systemic inflammation in this population. The gender of the patient, however, must be taken into consideration.
The effects of music tempo on performance, psychological and physiological variables during 20 km cycling in well-trained cyclists.
(2013) Dyer, Barry.; McKune, Andrew James.
Introduction Music is commonly used to accompany exercise and has been viewed as a type of legal performance enhancing drug due to its beneficial effects such as reduced RPE, increased work output, enhanced mood, enhanced motor skill acquisition, and increased performance during a variety of exercise tasks. Despite the fact that athletes report using music before, during and after training to increase performance and self-regulate mood, the majority of evidence available has been based on untrained, non-athletic populations. This highlights the need for further research into the effects of music on well-trained individuals engaging in exercise. Objectives The purpose of this study was to investigate the effects of different music tempi on performance, psychological and physiological responses of well-trained, experienced cyclists to time trial cycling. Methods Ten male road cyclists (age:35yrs ± 7, VO2 peak: 5.6 L/min ± 0.4; sum of 7 skinfolds: 58 ± 9.4) performed four 20km time-trials on a Computrainer™ Pro 3D electromagnetically braked indoor cycle trainer over a period of four weeks. The time-trials were spaced a week apart. The music conditions for each trial were randomised between fast-tempo (140 bpm), medium-tempo (120 bpm), slow-tempo (100 bpm), and no-music. Measures recorded during the time-trials included (1) physiological: heart rate, oxygen consumption, breathing frequency, respiratory exchange ratio, (2) psychological: mood states (Profile of Mood States (POMS) pre and post time-trial), (3) Performance: peak and average power output, time to completion, pedal cadence and (4) rating of perceived exertion. Averaged data were compared using one-way analysis of variance. Data for heart rate, oxygen consumption, breathing frequency, RPE, cadence and power output were also collected at three minute intervals during each trial. These were compared using two factor (time x condition) repeated measures analysis of variance. For all data sets, where a significant difference was observed, a Bonferroni post-hoc test was used to determine specific differences. Significance was set at P < 0.05. Results Results revealed no significant changes in physiological variables or performance variables. Total mood disturbance and tension as measured by the POMS were increased significantly in response to the fast-tempo trial. Conclusion Fast tempo music is often perceived as highly motivational and results in increased arousal in the listener. It is likely that prolonged exposure to arousing stimuli such as fast tempo music in conjunction with the intense sensations associated with time-trial exercise could have led to the disturbances in mood state observed during the fast-tempo music trial.
Five minute recordings of heart rate variability in physically active students : reliability and gender characteristics.
(2011) Sookan, Takshita.; McKune, Andrew James.
Introduction Heart rate variability (HRV) is regarded as a useful, non-invasive method for investigating the autonomic nervous system (ANS). Over the past decade there has been an increase in the number of HRV investigations in the disciplines of medical, sport and exercise science. Despite the extensive use of HRV in investigations of ANS functioning, there are questions relating to the reliability of the technique. Therefore, HRV reliability studies for different population groups have been advocated. Furthermore, research on gender differences in HRV is contradictory. This has resulted in the need to investigate gender characteristics in HRV. Objectives The objective of this study was to evaluate the reliability of short-term (5min) recordings of HRV, and to determine the association between HRV and gender. Methods Forty four physically active students (n= 21, age= 21.17 (1.55) males and n=23, age= 19.75 (1.76) females) participated in the study. Heart rate variability parameters were determined from five minute recording of interbeat intervals (IBI) using a Suunto t6 heart rate monitor (HRM). Testing was repeated over 4 consecutive days under the same conditions. The following HRV time and frequency domain measures were calculated using Kubios HRV Software Version 2.0: mean heart rate (HR), standard deviation of normal to normal intervals (SDNN), root mean square of successive differences (RMSSD), percentage of beats that changed more than 50 ms from the previous beat (pNN50), low frequency in normalized units (LFnu), high frequency in normalized units (HFnu) and low frequency to high frequency ratio in normalized units (LF/HFnu ratio). The data was summarized using routine descriptive statistics. Relative reliability was calculated using interclass correlation coefficients (ICC) (ICC of >0.80 indicated good to excellent reliability) and absolute reliability using typical error of measurement (TEM) and TEM as a percentage of the mean score (TEM%). This statistical measures were computed for days 2 vs 3 (REL 1), 3 vs 4 (REL 2). Day 1 was used as a familiarization day. An unpaired T-test was used to determine whether there were any differences between males and females for the above HRV parameters. Significance was set at p .0.05. Results The ICCs for both REL 1 and REL 2 indicated good to excellent (ICC >0.8) reliability for IBIs and pNN50 for the time domain results. In general, the time domain results had a higher relative reliability than the frequency domain results. Males had an overall lower relative reliability than females for frequency domain parameters. Absolute reliability for REL 2 showed a slightly lower TEM value as compared to REL 1.The largest gender differences in TEM were seen in the frequency domain parameters. Specifically, for males, the TEM was higher than females for the LF/HFnu ratio (REL 2: 116%), the HFnu (REL 1: 90%) and the LFnu (REL 1: 68%). Overall the TEM% was relatively high in most HRV parameters specifically for LF/HFnu (REL 1: 31.4% females and 48.1% males; REL 2: 29.7% females and 40.4% males). These findings indicate that males have decreased absolute reliability compared to females and that random error is greater in men for the frequency domain parameters. Gender differences illustrated significant differences for resting HR (16% higher in females (p < 0.0001)), IBIs (21% higher in females (p <0.0001)) and LF/HFnu ratio (41% higher in males (p = 0.003)). The findings indicate that females have higher total HRV. Conclusions Short term recordings of HRV over consecutive days using the Suunto t6 HRM and Kubios custom HRV software are reliable depending on the HRV parameter being analysed. Overall, the relative reliability results suggest that HRV using the Suunto t6 and Kubios is good. However, the absolute reliability results suggest low reliability. In particular, males demonstrated a poorer absolute reliability (high TEM and TEM%) than females, suggesting a larger day to day random error in males. Furthermore, specific HRV measures differed between males and females demonstrating that females have higher parasympathetic modulation compared to men. The overall higher HRV in females could explain the possible cardio-protective mechanism observed in premenopausal women. Key words: Heart rate variability, Parasympathetic, Reliability, Interbeat Intervals
Long distance running in Ethiopian athletes: a search for optimal altitude training.
(2018) Tola, Zeru Bekele.; McKune, Andrew James.
ABSTRACT Background The extended dominance of Ethiopian and Kenyan middle- and long- distance athletes in world athletics has resulted in researchers proposing numerous explanations to explain this success. Genetic predisposition, anthropometric, physiological, biochemical and biomechanical characteristics, environmental factors like living and training at high altitude, active lifestyles during childhood as well as nutritional practices, have all been major focus areas of past studies that involved east African endurance athletes. Of all the proposed variables, researchers have acknowledged the positive role of environmental factors in the success of these athletes. Despite the past attempts to investigate the major factors that contributed to the successes of east African athletes, to the best of the authors’ knowledge, limited studies have addressed each of the proposed physiological and environmental variables in the Ethiopian athletes, compared with the number of studies conducted on Kenyan athletes. Purpose The primary purpose of this research was to test a natural altitude training model and examine whether it enhanced the long-distance performance of junior Ethiopian athletes. The research also examined a variety of environmental factors associated with these junior athletes that included daily distance travelled to and from school, mode of transport to and from school as well as physical activity patterns after school. These factors were compared between the junior athletes who participated in the altitude training study, current and retired World and Olympic level long-distance Ethiopian athletes. The energy intake, macronutrient breakdown and energy expenditure of the junior athletes during the altitude training camp were also analysed. Methods Demographic Characteristics Study: A total of 83 endurance runners were involved in this study. The athletes were classified into three separate groups based on their current performance status and age as retired elite (n = 32), current elite (n = 31) and academy junior athletes (n = 20). The average ages of the athletes in the three groups were 38±7.6, 25±4.5, and 18±1.2 years for retired elite, current elite and junior group athletes, respectively. The study primarily employed a xvi questionnaire survey design to gather the demographic characteristics of the athletes. Along with the questionnaire, the altitudes where the athletes were born and trained, as well as the home to school distance of the athletes were measured. Data were collected from the retired athletes through both self- and interviewer-administered questionnaires and forms. Self-administered questionnaires were used to collect data from the current elite and academy junior athletes. Only 46.8% of the retired elites (n=15) filled in the questionnaire and the rest 53.2% (n=17) of the retired elite athletes responded to the questionnaire via telephone. The home to school distance of 71.8% (n = 23) and 58.1% (n = 18) of retired and current elite athletes, respectively, was measured physically using a watch with Global Positioning System (Garmin forerunner, 910X). Macronutrient Intake and Energy Balance Study: In this study, twenty (male = 16 and female = 4) junior long-distance athletes participated. The athletes were attending an eight-week training in the camp where they were living in and training in and around Tirunesh Dibaba National Athletics Training Centre (TDNATC) located at an altitude of 2500m (7°57′N latitude and 39°7′E longitude). The study used the three-day direct dietary record method. Nude body weight measurements were taken before and after the three assessment days. All food measurements were carried out when the three meals were served: breakfast (8:00 – 9:00am), lunch (12:00 am – 1:00pm), and dinner (6:00 – 7:00pm). All the measurements were taken and recorded by the principal investigator, together with the head coach of the athletes, using a digital weighing scale readable to 1 gram (Salter Housewares LTD, England) and the dietary analysis of each individual athlete, including the total energy intake, and the energy contribution and gram values for carbohydrate, fat and protein from the consumed foods was performed using the nutritional software package Nutritics (v3.7, University Edition). Training type, intensity and duration, as well as external load, including distance, time covered and speed of the training were recorded in a daily training diary over the three consecutive days. Total energy expenditure of each study participant was calculated from basal metabolic rate (BMR) using the Schofield equation (1985) and the physical activity ratio (PAR), and physical activity level (PAL). xvii Altitude Training Study: A total of 20 (male = 16 and female = 4) junior long distance athletes lived and trained in and around the Athletes Tirunesh Dibaba National Athletics Training Centre were recruited for the study. The study applied the balanced, randomised, experimental design. Before the athletes were randomly assigned to the live high - train high (LH-TH) control (n = 10 ) and live high - train high train low (LH-THTL) experimental (n = 10 ) groups, they were tested on a 5km track race at baseline (end of four pre-experimental weeks) and then assigned equally into the two groups based on their 5km performance (time) and gender. The study lasted for a continuous eight weeks where all the athletes lived in every day of the week, and trained light and moderate intensity sessions at an altitude of 2500m a.s.l. four times per week. In addition, the LH-TH and LH-THTL groups trained separately at 2500m and 1470m a.s.l. in high intensity sessions two days per week, respectively. During the study time, different haematological, autonomic, neuromuscular, subjective training monitor and five kilometre performance time trial tests were conducted. Resting haematological tests were conducted three times (baseline, week four and week eight). Sample blood was drawn from a cubital vein under standard conditions (off-training days, between 08:30 and 09:30 a.m. before breakfast and after a 10 minute rest period in a sitting position) in the haematology laboratory of the College of Health Sciences of Arsi University, Ethiopia at the specified time for complete blood count ( CBC) analysis. Like the haematological tests, three consecutive vagal related heart rate measurements (heart rate variability and one- and two-minute heart rate recovery measurements) were taken at baseline, week 4 and week 8. The heart rate variability measurements were taken early in the morning, before the athletes left for training, in their bedrooms (before leaving their beds). The one- and two-minute heart rate recovery tests were taken as soon as the three 5km time trials were completed at baseline, week 4 and week 8. Along with the CBC and vagal-related heart rate measurements, five consecutive neuromuscular fitness tests (at baseline, week 2, week 4, week 6 and week 8) using the common vertical jump tests (counter movement (CMJ) and squat jump (SJ) test) were conducted after 10 hours of light intensity training. For a total of 47 training sessions, subjective training load responses were collected using a session rating of perceived exertion (session-RPE) methods within 30 minutes after the end of the day’s workout. At baseline, week four and week eight xviii three 5km endurance performance tests were conducted on a 400m standardized synthetic track under standard conditions (at 2500m a.s.l. and between 07:00 – 08:00 a.m.). Results Demographic Characteristics Study: Although the demographic characteristics study identified significant difference between the three groups in the age at which formal training started (p < 0.001), no significant difference was identified between the groups (p > 0.05) regarding the altitudes where the athletes were born and raised. Moreover, the study reported no significant difference in the daily distance covered to and from school between the three groups during their primary education (p > 0.05) but not during their secondary education (p < 0.05). The study also revealed that there were significant regional distribution differences in the three groups (p = 0.002) where 81.3% of retired athletes and 55% of academy junior athletes were from central Ethiopia. There was also no significant difference (p = 0.05) between the three groups in the mode of transportation used to cover the daily distance to and from school. In addition to the above findings, this study also found no statistically significant difference in the types of major out-of-school activities between the three groups of athletes during their childhoods (p > 0.05). Macronutrient Intake and Energy Balance Study: There was a significant difference between the mean total energy intake (14593±895KJ.day-1 ) and mean total energy expenditure (13423± 1134 KJ.day-1 , p < 0.001) during the three days’ dietary assessment. Moreover, the daily total energy intake (EI) and energy expenditure (EE) throughout the three days for all subjects were also compared in the same way as the total EI and EE. In comparison to the daily energy expenditure, on day one there was a mismatch between EI (15682 ± 1599 KJ.day-1 ) and EE (12823 ± 1397KJ.day-1 , p = 0.000), and a positive energy balance was calculated. On day two there was no substantial difference between daily EI (14368 ± 1516KJ.day-1 ) and EE (13688± 1618 KJ.day-1 , p = 0.146). Similarly, there was also no significant difference between the EI (13728±412KJ.day-1 ) and EE (13757± 1390KJ.day-1 , p = 0.919) on day three. This study also confirmed no significant differences in the daily energy expenditure between the three days (p = 0.091). As compared to fat and protein, it appears that CHOs were the major energy source consumed during the three days. The overall proportion of the energy derived from the foods revealed that CHO provided 65.7% (±11.7 %); protein 18.7% (±6.9 %) and fat 15.4% (±4.9 %). xix When the overall proportions of energy intake (KJ) derived from the three macronutrients were analysed on a daily basis, there were statistically significant differences in CHO, protein and fat consumption across the three days, (p < 0.001). Moreover, substantial differences were identified in the day-to-day fat (p < 0.001) and protein (p < 0.001) consumption during the three dietary assessment days. Altitude Training Study Haematological Study: No statistically significant difference in RBC count was observed between the LH - TH and LH - THTL study groups following eight weeks of endurance training (∆0.05; CL ±0.029; p = 0.741; ES = 0.12). After eight weeks of endurance training no significant difference was observed in the haemoglobin concentration (p = 0.926), but substantially declined from baseline to week eight in both groups (Experimental: ∆-0.48; CL±0.46; p = 0.040; ES = - 0.35 and control: ∆-0.51; CL± 0.46; p = 0.030; ES = -0.37). This study also identified no substantial difference in haematocrit value between the two study groups following eight weeks of endurance training (∆0.2; CL±1.9; p = 0.832; ES = 0.06). Vagal-Related Heart Rate Response: The resting HRV (RMSSD) measurements revealed no meaningful differences between the LH-TH and LH - THTL groups (∆-0.18; CL±0.43; p = 0.407; ES = -0.29) from baseline to week eight in the experimental (∆0.05; CL±0.31; p = 0.761; ES = 0.08) and control (∆0.22; CL±0.31; p = 0.145; ES = 0.37) groups; although the changes in both groups were positive. The difference between the experimental and control groups, however, was negative and small (∆-0.29). The regression analysis also revealed no significant differences, both in the one-minute (∆4.4; CL±10.8; p = 0.413; ES = 0.47) and two-minute postexercise heart rate recovery (∆3.1; CL±10.4; p = 0.550; ES = 0.31), between the experimental and control groups. Neuromuscular Fitness/Fatigue Response: The CMJ test results revealed no significant difference between the two study groups following eight weeks of endurance training (∆0.5; CL±4.8; p = 0.829; ES = 0.06), although meaningful changes were identified both in the experimental (∆8.3; CL ±3.4; p = 0.001; ES = 0.92) and control (∆7.8; CL ±3.4; p = 0.001; ES = 0.86) groups from baseline to week eight. Significant changes in squat jump ability were xx observed, both in the experimental (∆4.8; CL±2.8; p = 0.001; ES = 0.69) and control (∆2.9; CL±2.8; p = 0.039; ES = 0.42) groups, following eight weeks of endurance training; but not between the groups (∆1.8; CL±3.9; p = 0.353; ES = 0.26). This study also confirmed no significant difference between the two study groups in the eccentric utilisation ratio following eight weeks of endurance training (∆-0.05; CL±0.16; p = 0.511; ES = -0.39). Training Load Response: The results of the analysis identified significant differences between the groups, and for all weekly training load responses of all training sessions, i.e., light, moderate and high-intensity training sessions (p = 0.019) and high intensity training sessions (p = 0.000). However, no substantial difference was identified between groups (p = 0.133) in the weekly load responses to the light and moderate intensity training sessions. Based on the results of the least significant difference, post-hoc meaningful differences were identified between the groups in their weekly load response to the total intensity training at week seven and eight; as well as at weeks one, five, seven and eight for the high intensity training sessions. Out of the 47 training sessions, light intensity sessions (< 4 RPE, less than the first ventilatory threshold) made up 87.2% of sessions in the experimental group and 68.1% in the control group, while 12.8% (Experimental group) and 31.9% (Control group) of the training sessions were completed at RPE > 4 < 7 RPE (between first and second ventilatory threshold). Five Kilometre Endurance Performance: After eight weeks of endurance training no significant difference in the 5km endurance performance was identified between the LH-TH and LH-THTL study groups (∆-12; CL ±25s; p = 0.335). Even though times for the 5km decreased significantly in the experimental group (∆-19; CL±18s; p = 0.037) from baseline to week eight, performance in the control group did not improve significantly (∆-7; CL ±18s; p = 0.440). Conclusions Demographic Characteristic Study: Significant difference was observed between the three groups in the age at which formal training started. However, no significant differences were identified between the three groups in the altitudes where the Ethiopian long-distance athletes were born and raised, the daily distance travelled to and from school, the mode of transportation and the major out-of-school activities during their childhood. Thus, the findings of this study xxi confirmed that the 20 junior athletes who were involved in the study shared common demographic characteristics with the retired and current elite Ethiopian long-distance athletes. Macronutrient Intake and Energy Balance Study: In line with the previous studies conducted on Kenyan and Ethiopian endurance athletes, the young long-distance Ethiopian athletes met the recommended daily macronutrient intake for carbohydrates and protein for endurance athletes. However, the study also identified that the athletes’ dietary fat consumption was below the recommended amount for endurance athletes. Moreover, based on the three-day dietary assessment results, the young Ethiopian endurance athletes were found to be in a state of positive energy balance one week before their first major competition of the year (albeit during the preparation phase of their yearly training plan). Altitude Study: The overall results of the current altitude study revealed that in most of the study variables (i.e., haematological, autonomic, neuromuscular, and endurance performance), except the subjective based training load response, statistically insignificant results were identified between the two study groups. However, when the results of the altitude study variables across time (baseline to week eight) were examined, athletes in the LH-THTL experimental group showed better progress in neuromuscular and lower training load responses which were accompanied with significant five kilometer endurance performance change; and lower or similar progress in haematological and autonomic regulation responses as compared with the LH-TH control group. It is noted that the ultimate purpose of any type of altitude training is enhancing the running performance while minimizing athlete’s susceptibility to injury. Taking these core concepts of athletic training and the physiological and performance changes of the current study in to consideration, the LH-THTL altitude training model was potentially the preferred optimal altitude training model to further enhance the past and existing long-distance performance of Ethiopian endurance athletes although further comprehensive studies are required to confirm the results. Future Directions In order to exhaustively investigate optimal altitude training models that better enhance the longdistance performance of athletes’ native to high altitude, more comprehensive, similar studies xxii should be designed. Moreover, to achieve stronger results, further studies should be conducted using larger sample sizes with balanced gender proportions, along with more subjective and objective training monitoring methods. Furthermore, future studies should consider additional altitude training models, be conducted over longer periods and during different phases of the yearly training plan (preparation, pre-competition, and competition). It is also recommended that future studies should design endurance performance tests at different altitudes (low and high) to enhance the local and international competition performance of Ethiopian long-distance athletes.
Salivary biomarkers of mucosal immunity and sympathetic activation in children : effects of body composition, cardio-respiratory fitness and exercise.
(2012) Konkol, Kristen F.; McKune, Andrew James.
Worldwide, overweight/obesity and associated chronic diseases such as type 2 diabetes, have reached epidemic proportions. Statistics show that overweight/obesity and chronic disease is prevalent amongst adults and children in South Africa. In addition to chronic disease/non-communicable diseases, overweight/obesity has been shown to alter immune and sympathetic activation. There is limited information on immune function (mucosal) and sympathetic activation on children both internationally and nationally and in particular investigating these parameters using non-invasive methods such as salivary biomarkers. The aim of this thesis was to investigate the levels of salivary biomarkers of immune function and sympathetic activation in children and determine the association with overweight/obesity, cardiorespiratory fitness (CRF) and increased physical activity (PA). Methods This thesis is divided into six chapters. These include an introductory chapter (Chapter One), a review of the literature (Chapter Two) and then three chapters that are written in article format and that have each been submitted to accredited journals for publication. Chapter Three is a review article that discusses salivary biomarkers in children as they relate to exercise, PA and obesity. Chapter Four is a study that examined salivary biomarkers of mucosal immunity and sympathetic activation as predicted by age, body composition and cardiorespiratory variables in one hundred and thirty-two black South African children (age 10.05 ± 1.68y, 74 females, 58 males). Chapter Five is a study that investigated salivary biomarkers of mucosal immunity and sympathetic activation in response to 12 weeks of soccer training in thirty-four black male South African children (11 – 13y) from a youth football training academy. Chapter Six includes a summary of the research findings, conclusions and well as recommendations for future research. A review of the literature revealed that participation in regular moderate intensity PA or exercise appears to enhance mucosal immunity (increases salivary IgA (sIgA)) in preadolescent children. In contrast, poor fitness and inactivity as well as strenuous training appear to compromise the mucosal immune system thereby increasing the risk of upper respiratory tract infections (URTIs). Children reporting higher levels of body fat and with a greater BMI appear to have lower sIgA levels and a greater incidence of infections. The limited research examining salivary C-reactive protein (sCRP) suggests a strong association between poor cardio-respiratory fitness (CRF) and/or overweight/obesity and inflammatory status in children based on elevated sCRP levels. Research surrounding salivary alpha-amylase (sAA) indicates that exercise can result in a marked increase in sAA as seen by an increase sympathetic activity via increased adrenergic activity in the salivary glands. The limited research suggests exercise may also pose a high stress on young athletes as seen with an increase in sAA. Additionally it appears that BMI may be a strong predictor of stress-induced sAA increases in children. Greater hypothalamic pituitary adrenal (HPA) axis response, as seen by increases in salivary cortisol, appear to be influenced greatly by increases in obesity. Higher salivary cortisol secretions have been observed in obese versus lean children in response to exercise. School study: The outcomes of the one-way ANOVAs examining the differences by body mass index (BMI) categories showed there were significant differences in weight (F = 83.64, df = 2, 129, P < 0.0001), BMI (F = 193.36, df = 2, 129, P < 0.0001), waist-to-hip ratio (F = 193.36, df = 2, 129, P < 0.0001), body fat percentage (F = 336.98, df = 2, 129, P = 0.0001), SBP (F = 5.72, df = 2, 129, P = 0.0042), DBP (F = 291.76, df = 2, 129, P < 0.0001), VO2max (F = 521.00, df = 2, 129, P < 0.0001), sAA concentration (F = 17.05, df = 2, 129, P < 0.0001), sAA secretion rate (F = 15.15, df = 2, 129, P < 0.0001), sIgA concentration (F = 11.30, df = 2, 129, P < 0.0001), and sIgA secretion rate (F = 8.08, df = 2, 129, P = 0.0005), between children of different BMI categories. According to the CDC-BMI-for-age standards, the participants were grouped into the following CDC-BMI-for-age categories: normal weight (< 85th percentile), overweight (≥ 85th percentile to < 95th percentile), and obese (≥ 95th percentile) (Ogden and Flegal, 2010). Tukey’s post hoc analyses revealed that obese children had significantly (P < 0.01) higher weight, BMI, body fat percentage, DBP, SBP, sAA concentration and secretion rate, compared to overweight and normal weight children, as well as a significantly lower aerobic capacity (VO2max) than both normal (P < 0.001) weight and overweight (P < 0.05) children. In addition, sIgA concentration and secretion rate were significantly lower between normal weight and obese children (P < 0.01). Multiple linear regression revealed that BMI, DBP and VO2max predicted sAA. BMI (P = 0.04) and DBP (P = 0.04) were found to be independent predictors of sAA concentration. Age and BMI category predicted sIgA secretion rate. BMI category (P = 0.0006) was found to be an independent predictor of sIgA secretion rate. Soccer study: Significant differences after 12 weeks of soccer specific training were found to be significant between pre vs. post for BMI (P =0.034), waist-to-hip ratio (P = 0.046), age (P < 0.0001), height (P < 0.0001), body fat % (P < 0.0001) and LMM (P < 0.0001). Decreases in BMI, waist-to-hip ratio, body fat % and LMM were found while age and height increased throughout the 12 weeks. Significant differences were also found between sIgA secretion rate pre vs. post training (P =0.025) as increases in these values pre to post were observed. Conclusions The results from the studies on the school children and soccer players suggested that mucosal immune function and sympathetic activation appear to be affected by body composition, CRF and chronic exercise training. The main findings for the school study revealed that BMI, DBP and VO2 predict sAA and that age and BMI category predict sIgA. This study also found that obesity (based on BMI) has a major role to play and that obese children have elevated sAA, lowered sIgA, and poor CRF. The finding of an increase in sIgA secretion rate in the soccer study suggested that a structured 12 week exercise programme can elevate mucosal immune function in youth soccer players. The underlying mechanism responsible may be an exercise-induced increase in the transport of sIgA across the mucosal epithelium and/or enhanced production of IgA in the mucosa via mediating cytokines. The literature review demonstrated that PA and overweight/obesity may have an impact on salivary biomarkers of mucosal immunity and sympathetic activation in children, however further research with regards to optimal intensity, duration and modality need to be assessed in the pre-pubescent population.Physical activity, obesity, immunity, neuro-endocrine, children, salivary biomarkers, sympathetic activation.
The use of laser doppler fluxmetry in the pre-operative assessment of amputation wound healing in the dysvascular patient.
(1997) McKune, Andrew James.; Mars, Maurice.; Robbs, John Vivian.
Abstract available in PDF.