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 rt.osistance to torsion is achieved hy modifying bone shape and mass, not necessarily bone density.

MMP2 and MMP9 plasma levels as markers of bone remodeling : a study on young male tennis players

Introduction
Our goal is to study the effects of tennis practice in pre-pubescent boys on bone remodeling, by means of enzyme activity involved in balance of matrix remodeling (MMP2 and MMP9).
Results
Mineral bone density has been found higher in the dominant arm (P < 0.0001) as well as MMP2 and MMP9 levels in plasma (P < 0.05).
Conclusion
Tennis practice in children increases bone remodeling, which can be assessed by MMP dosage, in addition of densitometry technique.

Highlights from the tennis Australia heritage collections : mini-exhibition in the player cafe, Rod Laver Arena

Summary : This 'mini-exhibition' arose as an opportunity to showcase recent acquisitions as well as established holdings of significant items of tennis related heritage within the Tennis Australia Heritage Collections. In general, the Collections have two main strengths, and the mini-exhibition was designed to communicate these. The first strength is the ability to show the evolution of tennis technology and practices over time, from the beginnings of modern tennis in the 1860s, to today. This evolution is a result of tennis being influenced by changes in the wider world, such as the Industrial Revolution. The second strength of the Collections is in showing the impact and influence of tennis on society. Many items in the Collections are evidence of the immense and enduring popularity of the sport across the world. The Collections contain many beautiful, rare and fascinating items of decorative arts, fashion, literature and social history which feature tennis as a motif. These items show the reverse influence - the deep impression tennis has made outside of the sport itself.  This mini-exhibition focuses on these two themes. Some displays focus on the first theme. They demonstrate the evolution of tennis racquets, tennis balls, instructional publications and other tennis related equipment over the past century and a half. Other displays focus on the second theme. There are cases which examine tennis' influence upon global popular culture, in board games, fashion and decorative arts from around the world.  The mini-exhibition includes items from the U.s, U.K., Germany, France, Austria, Japan and Australia, demonstrating the global phenomenon that tennis quickly became, and showcasing the international scope of the Collections.  Each case contains text panels listing the objects and their specifications, and panels providing contextual information about the display. The miniexhibition is expected to be on display until November 2009. A case-bycase breakdown of objects, with images and a layout map follows.

Tennis Australia : a case study of financial management for sport development at the club level

There has been substantial work that examines financial management in professional sport which has assisted scholars and practitioners to better understand processes and policies to ensure teams and leagues are sustainable (Andreff & Staudohar, 2000; Howard & Crompton, 2004; Kraekel, 2007; Lewis, Sexton, & Lock, 2007; Li, Hofacre, & Mahony, 2001). However, there has been a paucity of scholarly research that examines financial management at the grass roots levels of sport, and how this integrates with national sport organisation strategic planning, with the exception of the recent work by Havaris and Danylchuk (2007). This study aims to add to this gap in knowledge by examining financial management at the club level of tennis in Australia.

Tennis playing initiated before puberty leads to greater skeletal benefits in peri-pubertal boys than girls when training is maintained

Introduction: The purpose of the study was to compare the exercise-induced changes in bone mass and geometry between boys and girls.

Methods: Eighty competitive tennis players (43 boys, 37 girls) aged 7–19 years participated. Pubertal status was self-assessed using Tanner stages (TS 1–5). The dominant and nondominant humeri were compared for DXA-derived bone mass (BMC) and MRI-derived bone geometry [total bone area (TA), medullary area (MA) and cortical bone area (CA)].

Results/Discussion: Exercise-induced side-to-side differences in BMC, TA and CA were significant from TS1 to 5 in boys and girls (p < 0.06). Pre-pubertal (TS1) girls and boys show similar side-to-side difference in BMC after adjustment for training volume (19% vs. 15%, ns). Similar findings were found forTA and CA. In contrast, during puberty (TS2-4) boys displayed greater side-to-side differences than girls for BMC (27% vs. 18%, p < 0.05), TA (13–15% vs. 8%, p < 0.05) and CA (32% vs. 20%, p < 0.01), even after adjustment for tennis history. Girls partly compensated for the lack of an exercise-induced increase in bone size by a reduction of the medullary cavity on the dominant side (−5.5 to −13%, p < 0.05). In post-puberty (TS 5 or postmenarche), the size of the medullary cavity remained smaller on the dominant side in girls (−5% to −9%, p = 0.1–0.05??) whereas no such reduction was observed in boys.

Conclusion: Regular exercise initiated before puberty and maintained throughout puberty leads to greater skeletal benefits in peri-pubertal boys than girls for bone mass and bone size, two of the major determinants of bone strength.

Effects of long-term tennis playing on the muscle-bone relationship in the dominant and non-dominant forearms

The relationship between muscle strength and bone mineral density illustrates the positive effect of mechanical loading on bone. But local and systemic factors may affect both muscle and bone tissues. This study investigated the effects of long-term tennis playing on the relationship between lean tissue mass and bone mineral content in the forearms, taking the body dimensions into account. Fifty-two tennis players (age 24.2 +/- 5.8 yrs, 16.2 +/- 6.1 yrs of practice) were recruited. Lean tissue mass (LTM), bone area, bone mineral content (BMC), and bone mineral density were measured at the forearms from a DXA whole-body scan. Grip strength was assessed with a dynamometer. A marked side-to-side difference (p < 0.0001) was found in favor of the dominant forearm in all parameters. Bone area and BMC correlated with grip strength on both sides (r = 0.81 - 0.84, p < 0.0001). The correlations were still significant after adjusting for whole-body BMC body height, or forearm length. This result reinforced the putative role of the muscles in the mechanical loading on bones. In addition, forearm BMC adjusted to LTM or grip strength was higher on the dominant side, suggesting that tennis playing exerts a direct effect on bone.

Bone geometry in response to long-term tennis playing and its relationship with muscle volume : a quantitative magnetic resonance imaging study in tennis players

The benefit of impact-loading activity for bone strength depends on whether the additional bone mineral content (BMC) accrued at loaded sites is due to an increased bone size, volumetric bone mineral density (vBMD) or both. Using magnetic resonance imaging (MRI) and dual energy X-ray absorptiometry (DXA), the aim of this study was to characterize the geometric changes of the dominant radius in response to long-term tennis playing and to assess the influence of muscle forces on bone tissue by investigating the muscle–bone relationship. Twenty tennis players (10 men and 10 women, mean age: 23.1 ± 4.7 years, with 14.3 ± 3.4 years of playing) were recruited. The total bone volume, cortical volume, sub-cortical volume and muscle volume were measured at both distal radii by MRI. BMC was assessed by DXA and was divided by the total bone volume to derive vBMD. Grip strength was evaluated with a dynamometer. Significant side-to-side differences (P < 0.0001) were found in muscle volume (+9.7%), grip strength (+13.3%), BMC (+13.5%), total bone volume (+10.3%) and sub-cortical volume (+20.6%), but not in cortical volume (+2.6%, ns). The asymmetry in total bone volume explained 75% of the variance in BMC asymmetry (P < 0.0001). vBMD was slightly higher on the dominant side (+3.3%, P < 0.05). Grip strength and muscle volume correlated with all bone variables (except vBMD) on both sides (r = 0.48–0.86, P < 0.05–0.0001) but the asymmetries in muscle parameters did not correlate with those in bone parameters. After adjustment for muscle volume or grip strength, BMC was still greater on the dominant side. This study showed that the greater BMC induced by long-term tennis playing at the dominant radius was associated to a marked increase in bone size and a slight improvement in volumetric BMD, thereby improving bone strength. In addition to the muscle contractions, other mechanical stimuli seemed to exert a direct effect on bone tissue, contributing to the specific bone response to tennis playing.

Cortical and trabecular bone at the forearm show different adaptation patterns in response to tennis playing

Bone responds to impact-loading activity by increasing its size and/or density. The aim of this study was to compare the magnitude and modality of the bone response between cortical and trabecular bone in the forearms of tennis players. Bone area, bone mineral content (BMC), and bone mineral density (BMD) of the ulna and radius were measured by dual-energy X-ray absorptiometry (DXA) in 57 players (24.5 ± 5.7 yr old), at three sites: the ultradistal region (50% trabecular bone), the mid-distal regions, and third-distal (mainly cortical bone). At the ultradistal radius, the side-to-side difference in BMD was larger than in bone area (8.4 ± 5.2% and 4.9 ± 4.0%, respectively, p < 0.01). In the cortical sites, the asymmetry was lower (p < 0.01) in BMD than in bone area (mid-distal radius: 4.0 ± 4.3% vs 11.7 ± 6.8%; third-distal radius: 5.0 ± 4.8% vs 8.4 ± 6.2%). The asymmetry in bone area explained 33% of the variance of the asymmetry in BMC at the ultradistal radius, 66% at the mid-distal radius, and 53% at the third-distal radius. The ulna displayed similar results. Cortical and trabecular bone seem to respond differently to mechanical loading. The first one mainly increases its size, whereas the second one preferentially increases its density.

Short-term and long-term site-specific effects of tennis playing on trabecular and cortical bone at the distal radius

Mechanical loading during growth magnifies the normal increase in bone diameter occurring in long bone shafts, but the response to loading in long bone ends remains unclear. The aim of the study was to investigate the effects of tennis playing during growth at the distal radius, comparing the bone response at trabecular and cortical skeletal sites. The influence of training duration was examined by studying bone response in short-term (children) and long-term (young adults) perspectives. Bone area, bone mineral content (BMC), and bone mineral density (BMD) of the radius were measured by DXA in 28 young (11.6 ± 1.4 years old) and 47 adult tennis players (22.3 ± 2.7 years old), and 70 age-matched controls (12 children, 58 adults) at three sites: the ultradistal region (trabecular), the mid-distal region, and the third-distal region (cortical). At the ultradistal radius, young and adult tennis players displayed similar side-to-side differences, the asymmetry in BMC reaching 16.3% and 13.8%, respectively (P < 0.0001). At the mid- and third-distal radius, the asymmetry was much greater in adults than in children (P < 0.0001) for all the bone parameters (mid-distal radius, +6.6% versus +15.6%; third-distal radius, +6.9% versus +13.3%, for BMC). Epiphyseal bone enduring longitudinal growth showed a great capacity to respond to mechanical loading in children. Prolonging tennis playing into adulthood was associated with further increase in bone mineralization at diaphyseal skeletal sites. These findings illustrate the benefits of practicing impact-loading sports during growth and maintaining physical activity into adulthood to enhance bone mass accrual and prevent fractures later in life.

Asymmetry in volume between dominant and nondominant upper limbs in young tennis players

This study aimed at demonstrating the asymmetry in volume between the dominant and nondominant upper limbs in tennis players, controlled for maturity status. Upper limb volumes on both sides were calculated in 72 tennis players and 84 control subjects, using the truncated cone method. The participants’ maturity status was determined using the predicted age at peak height velocity (PHV). The results showed significant larger side-to-side asymmetry in volume in tennis groups than
in control groups. These findings suggested that, even before PHV, specific-sport adaptations occurred in the dominant upper limb in tennis players.