Bone mineral density of female long distance runners in Nelson Mandela Bay
- Authors: Meier, Catherine Anne
- Date: 2018
- Subjects: Running -- Physiological aspects , Marathon running -- South Africa -- Nelson Mandela Bay Municipality Bones -- Metabolism Mineral metabolism Running -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/22946 , vital:30153
- Description: Long distance running may present positive and negative effects on the bone mineral density (BMD) of such participants. The advantage of high impact loads placed on the body of these runners may be neutralised or reversed, as too high a load may cause a decreased BMD. Furthermore, competitive female runners are generally considered to be leaner than their peers due to the nature of the sport. Therefore, it is expected that the majority of these runners would have a low body fat percentage (BF%) and body mass index (BMI) which may negatively affect the BMD, resulting in impaired bone quality. Due to the general inaccessibility of BMD assessments because of the cost involved, the incidence of risk for lowered BMD among long distance runners and particularly female runners are not readily known. The primary aim of the present study was therefore to determine the BMD rating and its association with body composition (BF% and BMI) and other selected factors among female long distance runners in Nelson Mandela Bay (NMB). The study utilized a quantitative approach and was exploratory, descriptive and non-experimental in nature. Non-probability, convenience sampling was implemented. A total of 40 female long distance runners between the age of 25 and 68 years (with a mean age of 43.6 ± 9.67 years) who have completed at least two marathon events were included in the study. The study utilized a questionnaire to collect demographic and other relevant information from the participants; a stadiometer and an electronic scale to measure height and weight and ultimately calculate BMI; and a bone densitometer with Dual-Energy X-ray Absorptiometry (DXA) (Hologic Discovery W) to determine the various BMD variables required as well as the BF%. Three densitometry scans were performed by a qualified radiographer which presented four analyses namely that of the relevant BMD variables for the hip, lumbar spine and total body, respectively, as well as of the BF% for the total body. The results of the study in respect of the overall BMD profile of the female long distance runners was considered to be normal except for the lumbar spine, found to be osteopenic when considering the mean T-score for this region of those 50 years and older. Overall the participants had an ‘average’ BF% (26.71 ± 6.33%) classification according to the ACSM classification rating system and were classified as ‘normal’ (22.80 ± 2.58 kg/m²) in respect of the BMI category rating. Significant correlations (r ≥ 0.312) were found between BMI and BMD related Z-scores for the hip, lumbar spine and total body, respectively. When considering the effect of selected variables on the various BMD variables, BF% and BMI, respectively, the following significant (p < .05; d > 0.2) results were found: (1) BMD (one or more rating and or Z-score) was positively influenced (had higher ratings) in runners who were overweight, consumed alcoholic beverages of five or less per week and who ran less than 51 km/week, respectively; (2) BMD (one or more rating and or Z-score) was negatively influenced (had lower ratings) in runners who had more full-term pregnancies and among those who were menopausal, respectively; (3) BF% and BMI were both found to be lower in runners who: were not menopausal, competed in six or more ultra-marathon events, completed marathons in less than or equal to three hours and 50 minutes, had an incidence of breaking a bone due to a traumatic event, and engaged in an average weekly running distance of more than 50 km/week, respectively.
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- Date Issued: 2018
The impact of three different footwear conditions on individual biomechanical, physiological and perceptual responses during running.
- Authors: McDougall, Justin John
- Date: 2016
- Subjects: Running -- Physiological aspects , Running shoes -- Physiological aspects , Running -- Health aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5177 , http://hdl.handle.net/10962/d1019988
- Description: Background: Despite the introduction of running footwear in the 1970’s, running injury rates continue to be unacceptably high. The subsequent revival of barefoot running and the introduction of minimalist footwear occurred, in an attempt to reduce injury rates and increase performance. There is much contention in the literature around the effectiveness of these footwear conditions. Furthermore individual responses have recently been proposed to provide more accurate and reflective conclusions than the use of mean data. Objectives: Twofold: a) to compare the biomechanical, physiological and perceptual responses between the shod, minimalist and barefoot footwear conditions and b) to assess and compare individual responses under these footwear conditions. Methods: 26 well-trained, male, habitually shod endurance runners, aged between 18 - 30 years completed three experimental sessions on an indoor runway and motorized treadmill. Each session was completed in either the shod, minimalist or barefoot condition, running at 15km.h-1. Variables assessed included stride rate, stride length, impact peak, vertical impact and average loading rate and strike time (biomechanical); heart rate, oxygen consumption and electromyography (physiological); and rating of perceived exertion and body discomfort (perceptual). Results: Biomechanics – Stride rate and stride length showed a significant (p<0.001) increase and decrease respectively when running in the minimalist or barefoot conditions versus shod. Running barefoot versus the minimalist and shod conditions resulted in a significantly (p<0.001) greater vertical impact loading rate. Strike time was significantly (p=0.008) reduced running in the minimalist and barefoot conditions versus shod. Physiology – Running barefoot versus shod resulted in a significantly (p=0.02) reduced heart rate and Tibialis Anterior activity (p=0.005). There was a large variability in individual responses for many variables, with responders and non-responders seen. Conclusion: The study suggests that there are significant differences between all three forms of running for some variables. It was further noted that there is support for the proposal that individual responses are highly variable and should be analysed accordingly
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- Date Issued: 2016
Energetic and kinematic responses to morphology-normalised speeds of walking and running
- Authors: Williams, Martin Andrew
- Date: 1989
- Subjects: Running -- Physiological aspects , Walking -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5166 , http://hdl.handle.net/10962/d1016240
- Description: This study investigated the influence of human morphology upon selected physiological, biomechanical and psychological responses to horizontal locomotion. In so doing, it was possible to evaluate the effectiveness with which morphology-normalised speeds of walking and running reduced the between-subject variability that is inherent in human locomotor responses. Twenty caucasian males were divided into two groups on the basis of stature - ten subjects in each of a "short" category (<170cm) and a "tall" category (>185cm). All subjects were habituated to treadmill locomotion prior to exposure to three walking treatments (0.83, 1.39 and 1.94m.s⁻¹) and three running treatments (2.50, 3.06 and 3.61m.s⁻¹). During each of these five-minute locomotor conditions, energetic (V02), kinematic (cadence and stride length) and psychophysical (central and local RPE) data were captured. From these data, lines of best fit were calculated for each subject, allowing for a prediction of the abovementioned locomotor variables from known absolute rates of progression. Using suitable regression equations, subject responses to morphology-normalised speeds of walking and running were effectively extrapolated. When the rate of progression was expressed in absolute terms (m.s⁻¹), significant differences (P <0.05) were found between the stature-related groups with respect to both energetic and kinematic locomotor responses. Such differences were successfully eliminated when use was made of locomotor speeds relativised on the basis of morphology. This study concludes that the use of appropriately prescribed morphology-normalised rates of progression are effective in reducing the variability in locomotor responses between subjects differing significantly in stature.
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- Date Issued: 1989
The effects of relative speed on selected physiological, kinematic and psychological responses at walk-to-run and run-to-walk interfaces.
- Authors: Candler, Paul David
- Date: 1987
- Subjects: Walking -- Physiological aspects , Running -- Physiological aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5164 , http://hdl.handle.net/10962/d1016081
- Description: [Conclusions] l) The two forms of human locomotion, walking and running, are distinctly different and in evaluating these gait patterns consideration must be given to this fact. 2) The impression created by the energy cost curves, that there is a single locomotor interface for both walking and running is a false one . There are two distinctly different locomotor interfaces, the walk-to-run interface and the run-to-walk interface. The former appears to correspond with the "metabolic intersection point" and therefore has some metabolic significance. The latter appears to be merely an "overshoot" of the walk-to-run interface and presently has no apparent metabolic significance. 3) Because the walk-to-run interface speed corresponds with the intersection point of the energy cost curves, physiological responses to walking and running at this speed do not differ significantly. However, cadence and stride length patterns for these two locomotor patterns are distinctly different at this point. 4) The identification of single physiological or kinematic factors during perceptions of exertion in any given situation is an extremely difficult if not impossible task. Perceived exertion should therefore be considered a multi-factorial concept and should be evaluated as such. 5) The use of relative speed as a technique for reducing inter-subject variability in physiological and kinematic factors is worthless unless diverse ranges in morphological linearity are a characteristic of one's subject pool
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- Date Issued: 1987
Economy and efficiency of human locomotion
- Authors: Goslin, Brian Richard
- Date: 1985
- Subjects: Walking -- Physiological aspects , Running -- Physiological aspects , Human locomotion
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5142 , http://hdl.handle.net/10962/d1007177 , Walking -- Physiological aspects , Running -- Physiological aspects , Human locomotion
- Description: Human locomotor economy and efficiency are highly variable. This study investigated the role that stature plays in this variation, by evaluating metabolic and respiratory responses to walking and running at speeds set relative to one's stature. Four groups of subjects: male, high V0₂ max (n = 11); male, average V0₂ max (n = 10); female, high V0₂ max (n = 10); and female, average V0₂ max (n = 11) were habituated to treadmill locomotion prior to the measurement of maximal oxygen consumption (V0₂ max). The V0₂ max test entailed 1 km.h⁻¹ increases per min from 3 to 6 km.h⁻¹ walking, and 7 - 17 km.h⁻¹ running then 1% grade increments per min until exhaustion. On each of four other occasions, the subject walked or ran at 6 of a variety of relative speeds - walking at 0.5, 0.7, 0.9, 1.1, 1.3; running at 1.5, 1.7, 1.9 and for selected subjects 2.1, 2.3 and 2.5 statures.s⁻¹ ,and grades - 0%, +3%, -3%. Steady-state respiratory and metabolic responses, and treadmill speed were monitored by an on-line computer system developed for this study. Cadence and RPE were also monitored. All subjects demonstrated an exponential relationship between V0₂ and walking relative speed (st.s⁻¹) (RS) . V0₂ (ml.kg⁻¹.min⁻¹ ) = 4.747 * e(1.371*RS) During running this relationship was essentially linear . The variability of economy at relative speed (9.08%) and absolute speed (9. 01%) did not differ. Male and female subjects did not differ in response to absolute speed but females were more economical at relative speeds (p<0.05). Those with high and average aerobic capacity did not differ in locomotor economy at relative speed. Higher freely-chosen stride length was associated with a higher V0₂ response as velocity increased. The V0₂ of uphill walking was 1.4 times greater than that for downhill walking (running: 1.28 times) . Stride length decreased with increasing speed in uphill locomotion but the reverse was the case for downhill. The economy and efficiency of walking was greater than that of running. Walking economy was maximal between 0.7 and 0.9 st. s⁻¹. Running economy remained essentially unaffected by increased velocity. The setting of locomotor velocity relative to stature does not minimize inter-subject variability in metabolic and respiratory response .
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- Date Issued: 1985