CAPÍTULO VIII RÉGIMEN DISCIPLINARIO
DE LOS DERECHOS, DEBERES, PROHIBICIONES, INHABILIDADES E INCOMPATIBILIDADES
The purpose of this research study was to investigate the BMD of female long distance runners in Nelson Mandela Bay. The study aimed to describe and correlate the BMD, BF% and BMI of the sample participants as well as to identify the relationships that occurred between BMD, BF% and BMI respectively and each of a number of variables. For the purpose of this quantitative research study, a questionnaire as well as anthropometric and densitometry assessments were conducted, and appropriate statistical analyses applied in order to achieve the relevant objectives that were set.
The questionnaire, which constituted the first phase of gathering information, was implemented to identify demographical information, the female reproductive variables, bone health indicators, disease history, medication, lifestyle factors, training load, running shoe used and running style of the runners.
The second phase of assessments included the measuring of height and weight to determine BMI and subsequently facilitating the densitometry scans conducted by radiographers to determine the various BMD variables and BF%. A total of 40 female long distance runners participated in and completed the study. The research study was conducted at the Biokinetics and Sports Science Unit of the High Performance Complex at the Nelson Mandela University.
A final summary of the results obtained are as follows:
There was a total of 40 female runners who participated in the research study. The ages ranged between 26 years and 68 years of age with the majority being in the 31 to 50 years (n = 29) age category. The mean age and standard deviation of the participants involved were 43.6 ± 9.67 years.
The majority of the participants were members of running clubs (80%) and there was a total of 12 different running clubs from which the participants were drawn. The remaining participants met the inclusion criteria of the study but were not registered members of any club.
The BMI of the runners was determined based on the height and weight measurements that were taken. The majority of the participants (n = 34, 85%) were found to be within the ‘normal’ (22.02 ± 1.79 kg/m²) category for the BMI rating with the others (n = 6; 15%) being classified as ‘overweight (27.26 ± 1.67 kg/m²). The overall rating for the sample was also ‘normal’ based on the overall mean BMI (22.80 ± 2.58 kg/m²).
Based on the bone densitometry reports of the BF% of each individual, which were expressed in relation to age and interpreted according to normative data, the runners were classified as follows:
o Excellent (n = 7, 18%) (18.39 ± 3.15%) o Good (n = 7, 18%) (21.79 ± 2.52%) o Average (n = 6, 15%) (26.63 ± 3.13%)
o Below Average (n = 12, 30%) (29.825 ± 2.76%) o Poor (n = 8, 20%) (33.7 ± 4.94%)
The overall rating for the sample was ‘average’ based on the mean BF% of 26.71 ± 6.33% which was interpreted according to the mean age of the sample.
The runners’ mean Z-scores of the femoral neck, the hip total, the lumbar spine and the total body were all considered to be within the normal range. The mean values for the T-scores of the femoral neck, the hip total and the total body were also all considered to be within the normal range, whereas the lumbar spine was classified as osteopenic.
The Pearson-Product Moment Correlation analysis indicated a significant correlation (r ≥ 0.312) between the BMI and the Z-scores of the femoral neck, the hip total, the lumbar spine and the total body as well as the lumbar spine BMD respectively. There were no significant correlations found between BF% and the Z-scores or BMD values.
When comparing the mean values of BMD, BF% and BMI respectively in relation to various variables, inferential statistical analyses revealed no significant relationships in respect of:
The two age categories (Younger, 20-40 years versus Older, 41-70 years);
The age at which menarche occurred (Early, 10-12 years of age versus Late, 13+ years of age);
The use of contraceptive medication (Yes versus No) and the types of contraceptive medication used (Hormonal versus Barrier Methods);
Broken a bone due to a non-traumatic event (Yes versus No);
A family history of osteoporosis (Yes versus No);
The daily intake of medication (Yes versus No);
Cigarette smoking (Yes versus No);
The total number of long distance running years (<11 years versus >10 years);
The total number of marathons completed (≤10 versus ≥11);
The total number of completed long distance running events (<11 versus >10);
The implementation of a strength and conditioning program (Yes versus No).
When comparing BMD, BF% and BMI respectively in relation to a number of variables, inferential statistical analyses revealed specific significant (p < .05; d > 0.2) differences for the following comparisons:
Normal versus overweight (according to BMI classification):
Higher mean femoral neck (1.17 ± 0.75 versus 0.25 ± 0.95) and mean hip total (1.17 ± 0.782 versus 0.36 ± 0.84), Z-scores as well as a higher mean BF% (33.20 ± 3.77 versus 25.57 ± 6.02%) associated with an ‘overweight’ classification.
None versus one or more full-term pregnancies: Lower mean femoral neck Z-score (0.81 ± 0.12 versus 0.90 ± 0.11) associated with
one or more full-term pregnancies.
Menopausal versus non-menopausal females:
Higher mean femoral neck BMD (0.85 ± 0.10 versus 0.76 ± 0.11 g/cm²), mean lumbar BMD (1.05 ± 0.12 versus 0.92 ± 0.11 g/cm²) and mean total BMD (1.20 ± 0.11 versus 1.10 ± 0.11 g/cm²) associated with non-menopausal participants. An elevated mean BF% (31.28 ± 5.35 versus 25.03 ± 5.79%) was found in menopausal participants.
Breaking versus not breaking a bone due to a traumatic event:
A higher mean BMI (23.18 ± 2.57 versus 20.67 ± 1.41 kg/m²) was associated with not breaking a bone due to a traumatic event.
Consuming versus not consuming alcoholic beverages:
Higher mean lumbar BMD (1.05 ± 0.12 versus 0.93 ± 0.11 g/cm²) was associated with consuming alcoholic beverages. A higher mean femoral neck Z-score (0.58 ± 0.98 versus -0.29 ± 0.78) associated with consuming five or fewer alcoholic beverages per week.
Completing five or fewer versus six or more ultra-marathon running events:
A lower mean BF% (24.67 ± 6.81 versus 28.76 ± 5.21%) and mean BMI (21.86 ± 2.48 versus 23.75 ± 2.38 kg/m²) was associated with completing six or more ultra- marathon running events.
Completing a marathon in under three hours and 50 minutes versus more than three hours and 50 minutes:
A lower mean BF% (23.41 ± 8.03 versus 28.30 ± 4.72%) was associated with completing a marathon event in less than or equal to three hours and 50 minutes, a shorter duration.
Average running distance of 30-50 km/week versus 51-100 km/week:
A higher mean hip total Z-score (0.81 ± 0.77 versus 0.24 ± 0.89) was associated with an average weekly running distance of 30-50 km. A lower mean BF% (24.30 ± 5.31 versus 29.97 ± 6.27%) and mean BMI (21.85 ± 1.97 versus 24.10 ± 2.79 kg/m²) was associated with an average weekly running distance of 51-100 km.
In addition to the significant differences found, other non-significant trends were noted. The following trends are to be observed with caution as they were merely an observation of similarity and not due to any significant differences that were found. The trends were determined if all the variables presented a similar finding. Similarities were noted when the following sets of variables displayed the same trend: femoral neck, the hip total, the lumbar spine and total body for either the BMD or Z-scores respectively and the BF% and BMI.
The mean Z-scores for all variables were higher in the older age group (41-70 years of age) than in the younger age group (20-40 years of age).
The mean BMD and Z-scores for all variables were higher in the group that was classified as ‘overweight’ versus those in the ‘normal’ classification with regard to BMI classification.
The mean BF% and BMI was higher in those who use hormonal contraception as opposed to barrier methods.
The mean Z-scores for all variables were higher in those who had no incidence of breaking a bone due to trauma than in those who had. The BF% was also higher in those who had not broken a bone due to a traumatic event than in those who had.
The mean BMD and Z-scores for all variables were lower in those who take daily medication versus those who do not.
The mean BMD for all variables was higher in those who consume alcoholic beverages compared to those who do not. The mean BMD and Z-scores for all variables were higher in those who consumed five or fewer alcoholic beverages in comparison to those who consume more per week. The mean BF% and BMI was lower in those who consume more than 5 alcoholic beverages per week than in those who consumed 5 or fewer per week.
The mean Z-scores for all variables were lower in those who have participated in fewer than 11 years of long distance running compared to those who have participated in more than 10 years of long distance running. The BF% and BMI was higher in those who have participated in fewer than 11 years of long distance running compared to those who have participated for more than 10 years.
The mean Z-scores for all variables were lower in those who have completed 10 or fewer marathon events than in those who completed more.
The mean BMD for all variables was higher in those who have completed five or fewer ultra-marathon running events, whereas the mean BF% and BMI was lower in those who have completed six or more ultra-marathon running events.
The mean BMD for all variables was higher in those who have participated in fewer than 11 long distance running events, and the mean BF% and BMI was lower in those who have participated in more than 10 long distance running events
The mean BMD for all variables, as well as the mean BF% and BMI, was lower in those who completed a marathon in less than or equal to three hours and 50 minutes than in those who took longer to complete such events.
The mean BMD for all variables was higher in those who incorporate a strength and conditioning program during the week, but the mean Z-scores for all variables were lower in those who incorporate a strength and conditioning program during the week than in those who do not. The mean BF% and BMI was lower for those who implement a strength and conditioning program compared to those who did not.
5.9 CONCLUSION
From the results of the study of 40 female long distance runners, the following conclusions were drawn.
The overall Z-score and T-score values of the runners were found to be within the normal range, but the T-score value of the lumbar spine component was considered to be osteopenic, according to the normative data provided to interpret the Z-scores and T-scores. The overall BMD was found to be normal, as BMD is expressed by means of Z-scores.
The BF% and BMI of the runners overall were classified as ‘average’ and ‘normal’ respectively.
BMD-related Z-scores correlated significantly with the BMI of the runners, but not with their BF%.
BMD (one or more ratings and or Z-score), was positively influenced (had higher ratings), in runners who:
Were overweight.
Consumed five or fewer alcoholic beverages per week.
Ran less than 51 km/week.
BMD (one or more ratings and or Z-score), was negatively influenced (had lower ratings), in runners who:
Had more full-term pregnancies.
Were menopausal.
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 under three hours and 50 minutes.
Have an incidence of breaking a bone due to a traumatic event.
5.10 LIMITATIONS
Certain limitations were associated with this study and the list below needs to be considered.
The relatively small sample size limited the extent and power of the possible statistical analyses and the fact that convenience sampling was used also limits the generalisability of the results. Nevertheless, the results obtained do provide an insight into the BMD status of female long distance runners, an area of research that is otherwise sparsely informed.
The majority (all except two) of the female participants were Caucasian and the results are not reflective of different ethnicities. The study only included female long-distance runners, and the findings are limited to one gender.
To obtain the BMD results from the relevant scans, a qualified radiographer with the expertise to operate the bone densitometer was required. Two radiographers were used for this study due to circumstances out of the control of the primary researcher. This may have influenced the inter-observer reliability. Both were qualified professionals with specific experience in operating the relevant densitometer the impact of this limitation may be negligible.
5.11 RECOMMENDATIONS
The following are recommendations for future research:
The present study should be repeated but with a larger sample of runners and ensuring that there is enough representation of runners from each ten-year age band, including menopausal runners.
The present study should be repeated with other ethnic groups represented.
Experimental or intervention strategies should be implemented to identify the impact on runners and or other females presenting with lower than the norm for age BMD ratings.
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