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Biomedical subjects

R M Daly

Publications and source records attributed to R M Daly.

13 recordsLinked to original sources
PubMed2006

Lifetime sport and leisure activity participation is associated with greater bone size, quality and strength in older men.

INTRODUCTION: It remains uncertain whether long-term participation in regular weight-bearing exercise confers an advantage to bone structure and strength in old age. The aim of this study was to investigate the relationship between lifetime sport and leisure activity participation on bone material and structural properties at the axial and appendicular skeleton in older men (>50 years). METHODS: We used dual-energy X-ray absorptiometry (DXA) to assess hip, spine and ultradistal (UD) radius areal bone mineral density (aBMD) (n=161), quantitative ultrasound (QUS) to measure heel bone quality (n=161), and quantitative computed tomography (QCT) to assess volumetric BMD, bone geometry and strength at the spine (L(1)-L(3)) and mid-femur (n=111). Current (>50+ years) and past hours of sport and leisure activity participation during adolescence (13-18 years) and adulthood (19-50 years) were assessed by questionnaire. This information was used to calculate the total time (min) spent participating in sport and leisure activities and an osteogenic index (OI) score for each participant, which provides a measure of participation in weight-bearing activities. RESULTS: Regression analysis revealed that a greater lifetime (13-50+ years) and mid-adulthood (19-50 years) OI, but not total time (min), was associated with a greater mid-femur total and cortical area, cortical bone mineral content (BMC), and the polar moment of inertia (I (p)) and heel VOS (p ranging from <0.05 to <0.01). These results were independent of age, height (or femoral length) and weight (or muscle cross-sectional area). Adolescent OI scores were not found to be significant predictors of bone structure or strength. Furthermore, no significant relationships were detected with areal or volumetric BMD at any site. Subjects were then categorized into either a high (H) or low/non-impact (L) group during adolescence (13-18 years) and adulthood (19-50+ years) according to their OI scores during each of these periods. Three groups were subsequently formed to reflect weight-bearing impact categories during adolescence and then adulthood: LL, HL and HH. Compared to the LL group, mid-femur total and cortical area, cortical BMC and I (p) were 6.5-14.2% higher in the HH group. No differences were detected between the LL and HL groups. CONCLUSIONS: In conclusion, these findings indicate that long-term regular participation in sport and leisure activities categorized according to an osteogenic index [but not the total time (min) spent participating in all sport and leisure activities] was an important determinant of bone size, quality and strength, but not BMD, at loaded sites in older men. Furthermore, continued participation in weight-bearing exercise in early to mid-adulthood appears to be important for reducing the risk of low bone strength in old age.

Absorptiometry, Photon↗
PubMed2004

The relationship between muscle size and bone geometry during growth and in response to exercise.

As muscles become larger and stronger during growth and in response to increased loading, bones should adapt by adding mass, size, and strength. In this unilateral model, we tested the hypothesis that (1) the relationship between muscle size and bone mass and geometry (nonplaying arm) would not change during different stages of puberty and (2) exercise would not alter the relationship between muscle and bone, that is, additional loading would result in a similar unit increment in both muscle and bone mass, bone size, and bending strength during growth. We studied 47 competitive female tennis players aged 8-17 years. Total, cortical, and medullary cross-sectional areas, muscle area, and the polar second moment of area (I(p)) were calculated in the playing and nonplaying arms using magnetic resonance imaging (MRI); BMC was assessed by DXA. Growth effects: In the nonplaying arm in pre-, peri- and post-pubertal players, muscle area was linearly associated BMC, total and cortical area, and I(p) (r = 0.56-0.81, P < 0.09 to < 0.001), independent of age. No detectable differences were found between pubertal groups for the slope of the relationship between muscle and bone traits. Post-pubertal players, however, had a higher BMC and cortical area relative to muscle area (i.e., higher intercept) than pre- and peri-pubertal players (P < 0.05 to < 0.01), independent of age; pre- and peri-pubertal players had a greater medullary area relative to muscle area than post-pubertal players (P < 0.05 to < 0.01). Exercise effects: Comparison of the side-to-side differences revealed that muscle and bone traits were 6-13% greater in the playing arm in pre-pubertal players, and did not increase with advancing maturation. In all players, the percent (and absolute) side-to-side differences in muscle area were positively correlated with the percent (and absolute) differences in BMC, total and cortical area, and I(p) (r = 0.36-0.40, P < 0.05 to < 0.001). However, the side-to-side differences in muscle area only accounted for 11.8-15.9% of the variance of the differences in bone mass, bone size, and bending strength. This suggests that other factors associated with loading distinct from muscle size itself contributed to the bones adaptive response during growth. Therefore, the unifying hypothesis that larger muscles induced by exercise led to a proportional increase in bone mass, bone size, and bending strength appears to be simplistic and denies the influence of other factors in the development of bone mass and bone shape.

Adolescent↗
PubMed2003

Associations between self-reported dental status and diet.

The purpose of this study was to develop a battery of dental, nutritional and psychological health survey measures and to use this survey instrument to explore links between age, tooth loss and dietary risk. The survey was undertaken in a dental school and hospital. Forty-nine consecutive patients (age range 25-74 years) participated in this pilot study and completed the health survey instrument. A quarter of the patients reported changing dietary habits due to dental problems, 56% reported difficulty in chewing as a result of problems with their teeth or dentures, and 36% reported having to interrupt meals due to dental difficulties. Tooth number was associated with MNA scores (0.35, P=0.03, Pearson's correlation coefficient) and reported number of foods eaten (0.33, P=0.04, Pearson's correlation coefficient) from the questionnaire checklist. Lower MNA scores were associated with age (F=6.54; d.f.=1, 46; P<0.01) indicating that older adults were more at risk of poor nutritional status. Overall health was not rated as an important factor influencing food choice, and only 14% of the sample felt that they had nutritional problems. Poor diet and impaired food choice was associated with declining numbers of teeth and increasing age. Older adults may require dietary advice to increase awareness of the importance of a healthy diet.

Adult↗
PubMed2002

The effect of mechanical loading on the size and shape of bone in pre-, peri-, and postpubertal girls: a study in tennis players.

Exercise during growth results in biologically important increases in bone mineral content (BMC). The aim of this study was to determine whether the effects of loading were site specific and depended on the maturational stage of the region. BMC and humeral dimensions were determined using DXA and magnetic resonance imaging (MRI) of the loaded and nonloaded arms in 47 competitive female tennis players aged 8-17 years. Periosteal (external) cross-sectional area (CSA), cortical area, medullary area, and the polar second moments of area (I(P), mm4) were calculated at the mid and distal sites in the loaded and nonloaded arms. BMC and I(P) of the humerus were 11-14% greater in the loaded arm than in the nonloaded arm in prepubertal players and did not increase further in peri- or postpubertal players despite longer duration of loading (both, p < 0.01). The higher BMC was the result of a 7-11% greater cortical area in the prepubertal players due to greater periosteal than medullary expansion at the midhumerus and a greater periosteal expansion alone at the distal humerus. Loading late in puberty resulted in medullary contraction. Growth and the effects of loading are region and surface specific, with periosteal apposition before puberty accounting for the increase in the bone's resistance to torsion and endocortical contraction contributing late in puberty conferring little increase in resistance to torsion. Increasing the bone's resistance to torsion is achieved by modifying bone shape and mass, not necessarily bone density.

Adolescent↗
PubMed2001

Balancing the risk of injury to gymnasts: how effective are the counter measures?

BACKGROUND: To minimise injury risk and maximise gymnastics performance, coaches, parents, and health professionals working with young gymnasts need to understand and practise safe gymnastics. AIMS: To (a) identify the various injury counter measures specific to gymnastics, (b) critically review the literature describing each injury prevention measure, and (c) assess, using available risk factor and injury data, the weight of evidence to support each of these counter measures. Specific recommendations for further research and implementation strategies to prevent injury and improve safety are also given. METHODS: The relevant literature was identified through the use of Medline (1966 to May 1998) and SPORT Discus (1975 to May 1998) searches, hand searching of journals and reference lists, and discussions with key Australian gymnastics organisations. RESULTS: The key gymnastics injury counter measures identified in this review include coaching (physical preparation, education, spotting, and performance technique), equipment, and the health support system (medical screening, treatment, and rehabilitation). Categorisation of the type of evidence for the effectiveness of each of these counter measures in preventing injury showed that most of it is based on informal opinion/anecdotal evidence, uncontrolled data based studies, and several prospective epidemiological studies. There is no evidence from formally controlled trials or specific evaluation studies of counter measures for gymnastics. CONCLUSIONS: Although gymnastics is a sport associated with young participants and frequent high volume, high impact training, there is a paucity of information on injury risk factors and the effectiveness of injury practices. Further controlled trials are needed to examine the extent to which injury prevention counter measures can prevent or reduce the occurrence of injury and re-injury. Particular attention should be devoted to improving training facilities, the design and testing of apparatus and personal equipment used by gymnasts, and coaching and the role of spotting in preventing injury.

Athletic Injuries↗
PubMed2000

Short stature in competitive prepubertal and early pubertal male gymnasts: the result of selection bias or intense training?

OBJECTIVES: To determine whether high-volume, high-impact physical training in prepubertal and early pubertal male gymnasts is associated with reduced statural and segmental growth and reduced serum insulin-like growth factor-I (IGF-I) and increased cortisol (C) levels. STUDY DESIGN: Height, sitting height, leg length, and segmental lengths (humerus, radius, femur, and tibia) and breadths (biacromial and bi-iliac), diet, serum IGF-I, testosterone, and C were measured in competitive male gymnasts and normoactive children (Tanner stage < or = 2) every 3 to 4 months over an 18-month period. RESULTS: At baseline, gymnasts (n = 31) were 0.7 years older than members of the control group (P <.05, n = 50) but were no different in terms of biologic maturity. Age-adjusted z scores showed that the gymnasts were shorter than members of the control group (-0.5 +/- 0.2 SD, P <.05) because of reduced leg length (-0.8 +/- 0.2 SD, P <.001) but not sitting height. Segmental lengths and bi-iliac breadth age-adjusted z scores were also reduced in the gymnasts (P ranging <.05 to <.001). No difference was detected for serum IGF-I or C. After 18 months of follow-up, no differences were found for rates of change in height, sitting height or leg length, segmental lengths, IGF-I, or C between those gymnasts and control subjects who remained prepubertal and early pubertal (gymnasts n = 18; control group n = 35). However, the magnitudes of baseline differences in anthropometric measures (z scores) persisted throughout the study. CONCLUSION: Short stature in these competitive male gymnasts was due to a reduced leg length but not sitting height. The lack of a difference in growth rates, IGF-I, and diet over the 18-month period indicates that the short stature reported in male gymnasts is due to selection bias rather than gymnastics training.

Adolescent↗
PubMed1999

Effects of high-impact exercise on ultrasonic and biochemical indices of skeletal status: A prospective study in young male gymnasts.

Physical activity has been proposed as one strategy to enhance bone mineral acquisition during growth. The aim of this study was to determine whether frequent impact loading associated with gymnastics training confers a skeletal benefit on pre- and peripubertal male gymnasts. We measured broadband ultrasonic attenuation (BUA, dB/MHz) at the calcaneus (CBUA); ultrasound velocity (m/s) at the calcaneus (CVOS), distal radius (RVOS) and phalanx (PVOS); serum osteocalcin (OC); total alkaline phosphatase (ALP) and insulin-like growth factor-I (IGF-I) every 3-4 months over an 18-month period in elite male gymnasts and matched normoactive controls (pubertal stage </=2). Ground reaction forces of common gymnastics maneuvers were determined using a force platform and loading histories of the upper and lower extremities approximated from video recordings. Ultrasound results were expressed as a standardized score (Z score) adjusted for age, height, and weight. At baseline, no differences were detected between the gymnasts (n = 31) and controls (n = 50) for CBUA, although ultrasound velocity at each site was higher in the gymnasts (0.6-1.5 SD) than the predicted mean in controls (p </= 0. 001). Over 18 months, CBUA Z scores increased significantly in the gymnasts from baseline (0.3 vs. 1.0, p < 0.05, n = 18). In contrast, ultrasound velocity did not increase in either group, although CVOS and RVOS remained significantly higher in gymnasts compared with controls (range p < 0.01 and < 0.001). No differences between groups were found for OC, ALP, or IGF-I at any time. Gymnastics training was associated with on average 102 and 217 impacts per session on the upper and lower extremities, respectively, with peak magnitudes of 3.6 and 10.4 times body weight. These results suggest that frequent high-impact, weight-bearing exercise during the pre and peripubertal period may enhance the mechanical competence of the skeleton, perhaps offering an important strategy for osteoporosis prevention if the benefits are maintained.

Body Constitution↗
PubMed1998

Hormonal responses to physical training in high-level peripubertal male gymnasts.

The effects of performing intensive training during growth remains controversial, with claims of negative effects upon growth and maturation purportedly due at least in part to a combination of hormonal disturbances and inappropriate nutrition. We examined the training-related responses of total testosterone (T), insulin-like growth factor-1 (IGF-1), cortisol (C) and diet in 16 peripubertal (pubertal stage <2) male gymnasts [mean (SD) age 10.5 (0.9) years, training 17.2 (5.6) h x week(-1)] and 17 controls [mean (SD) age 9.6 (1.2) years] over a 10-month period. Fasted, resting morning blood samples (0730-0900 hours) were taken from all children on Monday, Wednesday and Friday during a single week towards the end of each of three phases of gymnastics training: routine development (RD), precompetition (PC) and strength conditioning (SC). Serum concentrations of T, C and IGF-1 did not differ between the groups at any time. The ratio between IGF-1 and cortisol was significantly reduced in gymnasts relative to controls during RD and SC training (P<0.05), although no differences were detected for the T:C ratio. Diet did not correlate with any of the hormonal measurements, and no intergroup differences were found for the rate of growth in height. In summary, these results suggest that either the gymnastics training performed by these subjects was not intense enough to alter adrenal function, or that the gymnasts were well adapted to the training. In contrast, the reduction in the anabolic to catabolic balance represented by the IGF-1:C ratio is suggestive of a catabolic state, perhaps resulting from overstrain, insufficient recovery and/or inadequate caloric intake relative to energy output. While physical training during growth may induce a catabolic state, further research is needed to determine the biological significance of this finding, particularly with regard to growth and maturation.

Child↗
PubMed1997

Influence of high impact loading on ultrasound bone measurements in children: a cross-sectional report.

Evidence suggests that weight-bearing exercise during the growing years may enhance peak bone mass. The purpose of this study was to compare ultrasound bone measurements, serum alkaline phosphatase (S-ALP), serum osteocalcin (S-OC), and dietary calcium in highly active and normal healthy male children. Subjects were 33 elite and subelite male gymnasts and 40 normoactive controls matched for age (9.4 +/- 1.1 years), height (133.9 +/- 5.9 cm), and weight (30.1 +/- 3.8 kg). Measurements of broadband ultrasound attenuation (dB/MHz) through the calcaneus (CBUA) and ultrasound velocity (m/s) through the calcaneus (CVOS), distal radius (RVOS), and proximal phalanx of the index finger (PVOS) were performed using a Contact Ultrasonic Bone Analyzer (CUBA Research). Gymnasts had significantly greater CVOS (P < 0.001), RVOS (P < 0.0001), and PVOS (P < 0.05). There were no differences in CBUA, S-ALP, or S-OC between groups. RVOS correlated significantly with dietary calcium intake in all subjects (P < 0.05) and training time in the gymnasts (P < 0.05). Though gymnasts had significantly greater calcium intakes than controls (P < 0.05), whose mean value was below the RDA, after controlling for calcium intake in the gymnasts alone, RVOS was still significantly correlated with training time (P < 0.05). These preliminary results suggest that the heavy musculoskeletal loading inherent in gymnastics training produces positive adaptive responses in the growing skeleton. Furthermore, ultrasound appears to provide a safe, noninvasive means of comparing the skeletal status of exercising and normal healthy children, whereas single samples of biochemical markers did not discriminate between the groups.

Bone Density↗