Bone asymmetries in the limbs of children tennis players: testing the combined effects of age, sex, training time, and maturity status

Inter-arm bone mass and size asymmetries in children tennis players are maturity status specific: a 9-month study on the effects of training time across pubertal change and somatic growth

PURPOSE

Bone growth with exercise is best assessed by tennis-induced inter-arm asymmetries. Yet, the effects of training and maturation across puberty were unclear. This study explored arm bone growth across 9 months of training in 46 tennis players 7-14 years (25 boys, 21 girls).

METHODS

Bone mineral content (BMC) and bone area (BA) were measured from DXA scans. Pubertal status was assessed by Tanner stage (TS) and somatic growth by maturity offset (MO). Children were grouped as pre- (TS I-I), early (TS I-II), and mid/late pubertal (TS II-III).

RESULTS

Training time (TT) change in the three groups was 160-170, 190-230, and 200-220 h, respectively. Bone asymmetries were large in all groups (d > 0.8, P < 0.001): 5-18 g (9-21%) and 9-17 g (17-23%) in girls and boys, respectively, for BMC, and 5-15 cm2 (6-13%) and 9-15 cm2 (12-15%) in girls and boys (10-13%), respectively, for BA. BMC and BA change asymmetry peaked at pre-puberty in girls (56%, 46%) and at early puberty in boys (57%, 43%). Asymmetry gains varied with baseline asymmetry (41%) and change in TT (38%) and TS (17%) in BMC, and with baseline asymmetry (58%) and change in MO (17%) and TS (12%) in BA.

CONCLUSION

All bone asymmetries were substantial. Tennis-induced bone gains were higher at pre- to early puberty in girls and at early to mid/late puberty in boys. Training enhanced mostly bone mass and maturity status enhanced mostly bone size; sex was not bone-change modeling impactful. Implications are discussed considering certain limitations.

Intra-observer reproducibility and inter-observer agreement of Fels skeletal age assessments among male tennis players 8-16 years

BACKGROUND

Skeletal age (SA) is an estimate of biological maturity status that is commonly used in sport-related medical examinations. This study considered intra-observer reproducibility and inter-observer agreement of SA assessments among male tennis players.

METHODS

SA was assessed with the Fels method in 97 male tennis players with chronological ages (CA) spanning 8.7-16.8 years. Radiographs were evaluated by two independent trained observers. Based on the difference between SA and CA, players were classified as late, average or early maturing; if a player was skeletally mature, he was noted as such as an SA is not assigned.

RESULTS

The magnitude of intra-individual differences between repeated SA assessments were d = 0.008 year (observer A) and d = 0.001 year (observer B); the respective coefficients of variation were 1.11% and 1.75%. Inter-observer mean differences were negligible (t = 1.252, p = 0.210) and the intra-class correlation coefficient was nearly perfect (ICC = 0.995). Concordance of classifications of players by maturity status between observers was 90%.

CONCLUSION

Fels SA assessments were highly reproducible and showed an acceptable level of inter-observer agreement between trained examiners. Classifications of players by skeletal maturity status based on assessments of the two observers were highly concordant, though not 100%. The results highlight the importance of experienced observers in skeletal maturity assessments.

Lumbar spine bone mineral adaptation: cricket fast bowlers versus controls

Elite adult male fast bowlers have high lumbar spine bone mineral, particularly on the contralateral side to their bowling arm. It is thought that bone possesses its greatest ability to adapt to loading during adolescence, but it is unknown at what age the greatest changes in lumbar bone mineral and asymmetry develops in fast bowlers.

Objectives

This study aims to evaluate the adaptation of the lumbar vertebrae in fast bowlers compared to controls and how this is associated with age.

Methods

91 male fast bowlers and 84 male controls aged 14-24 years had between one and three annual anterior-posterior lumbar spine dual-energy-X-ray absorptiometry scans. Total (L1-L4) and regional ipsilateral and contralateral L3 and L4 (respective to bowling arm) bone mineral density and content (BMD/C) were derived. Multilevel models examined the differences in lumbar bone mineral trajectories between fast bowlers and controls.

Results

At L1-L4 BMC and BMD, and contralateral BMD sites, fast bowlers demonstrated a greater negative quadratic pattern to their accrual trajectories than controls. Fast bowlers had greater increases in BMC in L1-L4 between 14 and 24 years of 55% compared with controls (41%). Within vertebra, asymmetry was evident in all fast bowlers and increased by up to 13% in favour of the contralateral side.

Conclusions

Lumbar vertebral adaptation to fast bowling substantially increased with age, particularly on the contralateral side. The greatest accrual was during late adolescence and early adulthood, which may correspond with the increasing physiological demands of adult professional sport.

STRENGTH TRAINING IN THE LOWER LIMBS OF SOCCER PLAYERS

ABSTRACT Introduction: The isometric weight training method combines the benefits of physical endurance and hypertrophy. This teaching method performs the isometric exercise with the appropriate body weight. Objective: Study the effects of isometric training with weights on soccer players’ explosive strength of the lower limbs. Methods: Twenty soccer players were randomly selected and divided equally into experimental and control groups. The real training situation of the athletes was used. The experimental group adopted the isometrics teaching method with weight, while the control group used conventional muscle strength training. The lower limb strength of the two groups of athletes was compared before and after the experiment. Results: The extensor force growth rate in the experimental groups was significantly increased at medium, high and low speeds, while the peak torque did not show significant changes. The soccer players had their muscle strength improved. There was a significant difference between the two groups (P<0.05). Conclusion: Isometric weight training significantly improves mid and fast-extensor muscle strength in young soccer players. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Bone Tissue Responsiveness To Mechanical Loading-Possible Long-Term Implications of Swimming on Bone Health and Bone Development

PURPOSE OF REVIEW

To revisit the bone tissue mechanotransduction mechanisms behind the bone tissue response to mechanical loading and, within this context, explore the possible negative influence of regular swimming practice on bone health, particularly during the growth and development period.

RECENT FINDINGS

Bone is a dynamic tissue, responsive to mechanical loading and unloading, being these adaptative responses more intense during the growth and development period. Cross-sectional studies usually report a lower bone mass in swimmers compared to athletes engaged in weigh-bearing sports. However, studies with animal models show contradictory findings about the effect of swimming on bone health, highlighting the need for longitudinal studies. Due to its microgravity characteristics, swimming seems to impair bone mass, but mostly at the lower limbs. It is unkown if there is a causal relationship between swimming and low BMD or if other confounding factors, such as a natural selection whithin the sport, are the cause.

Physical Fitness and Upper Limb Asymmetry in Young Padel Players: Differences between Genders and Categories

This study aimed to assess the physical fitness and upper body asymmetries of young padel players aged between 13 and 16 years and to determine the possible differences between genders and categories. A total of 60 padel players were divided into four groups: under-14 male (n = 15; age: 13.75 ± 0.45 years; height: 1.64 ± 0.07 m; weight: 54.7 ± 8.3 kg), under-14 female (n = 15; age: 13.75 ± 0.44 years; height: 1.60 ± 0.05 m; weight: 51.5 ± 6.0 kg), under-16 male (n = 15; age: 15.44 ± 0.51 years; height:1.71 ± 0.04 m; weight: 63.88 ± 6.2 kg) and under-16 female (n = 15; age:15.46 ± 0.52 years; height:1.63 ± 0.05 m; weight: 55.08 ± 3.6 kg). Handgrip strength, ischiosural flexibility, gestural speed of the dominant arm, vertical jump, cardiorespiratory capacity, lateral movement, lateral acceleration and reaction time were measured. Male players showed better results in manual grip strength, vertical jump power, cardiorespiratory capacity and lateral movement (p < 0.05). Moreover, males presented a higher percentage of asymmetry in upper limb strength. Female players showed better reaction time and greater flexibility (p < 0.05). Regarding the differences between categories, the under-16 players showed greater flexibility, gestural speed, vertical jump power, cardiorespiratory capacity and lateral movement compared to the under-14 players. These results can be used as reference values for coaches/physical trainers of younger categories to improve health control and physical performance planning.

Age-Related, Sport-Specific Dysfunctions of the Shoulder and Pelvic Girdle in Athletes Table Tennis Players. Observational Study

Background: Postural skills are fundamental in motor activities, so far no evidence of a direct relationship has been found, it is therefore recommended to consider the following directions, the higher the level of sports competition, the better the body posture; or better athletes also have a better body posture. Around the age of 11-14 years, it is a period of aggressive development, if the rapid growth of the bone system is not associated and symmetrical with the development of soft tissues serious postural deficiencies may develop in table tennis players. Methods: We used the web camera – photographic method (38) related to the Sensor Medica software that allows the acquisition of images in order to detect postural deficiencies and we considered it necessary to have a clear image of the level of technical-tactical training of female juniors III using 5 tests specific to topspin attack in order to assess the influence of body posture on such tests. Eighteen female juniors III (the mean ± SD age, height and weight were 11.1 ± 0.2 years, 147.7 ± 2.6 cm, 39.0 ± 2.0 kg). Descriptive statistical analysis was performed on the procedures for establishing the normality of data distribution, Levene's Test for Equality of Variances, the t test for independent samples. The confidence interval was set at 95% (p < 0.05), Results and Conclusions: Since Sig. (2-tailed) or p < α = 0.001 and taking into account that the confidence interval limits for the difference between the sample mean and the reference value (95% CI for the mean difference) do not contain the zero value, it is accepted that there are statistically significant differences between the shoulder inclination for the female athletes in the sample studied and the reference value. We identified that at the level of alignment between anatomical landmarks, the percentage of deficiency of the entire lot of female juniors III in the case of shoulders is 100% and at the level of PSIS is 66%, which validates several studies that stated that in this period of aggressive growth correlated with repetitive unilateral executions specific to the topspin attack lead to postural deficiencies. In terms of the influence of body posture on the quality level, we identified that Group 1 – (without PSIS imbalance) has a higher average overall efficiency of the 5 tests (11.33) compared to Group 2 (8.58), even if from a statistical point of view these differences are not significant. Keywords: Body posture, Asimmetry, Topspin attack, Table tennis, Sensor Medica,

Bone Microarchitecture and Strength Adaptation to Physical Activity: A Within-Subject Controlled HRpQCT Study

PURPOSE

Physical activity benefits bone mass and cortical bone size. The current study assessed the impact of chronic (≥10 yr) physical activity on trabecular microarchitectural properties and microfinite element analyses of estimated bone strength.

METHODS

Female collegiate-level tennis players (n = 15; age = 20.3 ± 0.9 yr) were used as a within-subject controlled model of chronic unilateral upper-extremity physical activity. Racquet-to-nonracquet arm differences at the distal radius and radial diaphysis were assessed using high-resolution peripheral quantitative computed tomography. The distal tibia and the tibial diaphysis in both legs were also assessed, and cross-country runners (n = 15; age = 20.8 ± 1.2 yr) included as controls.

RESULTS

The distal radius of the racquet arm had 11.8% (95% confidence interval [CI] = 7.9% to 15.7%) greater trabecular bone volume/tissue volume, with trabeculae that were greater in number, thickness, connectivity, and proximity to each other than that in the nonracquet arm (all P < 0.01). Combined with enhanced cortical bone properties, the microarchitectural advantages at the distal radius contributed a 18.7% (95% CI = 13.0% to 24.4%) racquet-to-nonracquet arm difference in predicted load before failure. At the radial diaphysis, predicted load to failure was 9.6% (95% CI = 6.7% to 12.6%) greater in the racquet versus nonracquet arm. There were fewer and smaller side-to-side differences at the distal tibia; however, the tibial diaphysis in the leg opposite the racquet arm was larger with a thicker cortex and had 4.4% (95% CI = 1.7% to 7.1%) greater strength than the contralateral leg.

CONCLUSION

Chronically elevated physical activity enhances trabecular microarchitecture and microfinite element estimated strength, furthering observations from short-term longitudinal studies. The data also demonstrate that tennis players exhibit crossed symmetry wherein the leg opposite the racquet arm possesses enhanced tibial properties compared with in the contralateral leg.

Benefits of Regular Table Tennis Practice in Body Composition and Physical Fitness Compared to Physically Active Children Aged 10-11 Years

The aim of this study was to identify the differences in body composition and physical fitness between children who played table tennis regularly during a two-year period compared to physically active children who were not engaged in a regular activity. Three hundred seventy-four children aged 10 to 11 years were divided into two groups: table tennis players (n = 109 boys and 73 girls) and physically active group (n = 88 boys and 104 girls). Anthropometric analysis included body mass index, skinfolds, perimeters and bone diameters. Somatotype and body composition were determined according to age-specific equations. Physical fitness assessment included hand grip dynamometry (strength), sit-and-reach test (range of movement) and maximal multistage 20 m shuttle run test (cardiovascular fitness). The result show that children who regularly played table tennis had greater bone development and superior physical fitness compared to those who were physically active but not engaged in a regular physical activity. This is the largest study to date presenting data about the potential of table tennis to benefit health in children. These results constitute an important first step in clarifying the effectiveness of table tennis as a health-promotion strategy to encourage children to undertake regular physical activity and limit sedentary behavior.