Development of Upper-Extremity Morphological Asymmetries in Male and Female Elite Youth Tennis Players: A Longitudinal Study.

PURPOSE: This 2-year longitudinal study examined the development of upper-extremity bone mineral density (BMD), bone mineral content (BMC), and lean mass (LM) asymmetry magnitudes in male and female youth tennis players. METHODS: Dominant and nondominant upper-extremity BMD, BMC, and LM values of 49 male and 31 female players were measured yearly using dual X-ray absorptiometry. From these values, asymmetry magnitudes were calculated and expressed as a percentage. Maturity offset was estimated using anthropometric measurements. Linear mixed effect models examined the development of BMD, BMC, and LM asymmetry magnitudes according to players' maturity offset, sex, and training volume. RESULTS: Adjusted for sex and training volume, a 1-year increment in maturity offset was associated with a significant increase in BMD (1.3% [2.2%]; P < .001) and BMC (0.6% [2.4%]; P = .011) asymmetry magnitudes. Male players displayed significantly higher LM asymmetry magnitudes (Δ3.2% [8.4%]; P = .002) compared with their female counterparts. Training volume was not significantly associated with asymmetry magnitude development. CONCLUSION: In contrast to LM, male and female youth tennis players' upper-extremity bones are still responsive to mechanical loading with a significant increase in BMD and BMC asymmetry magnitudes according to maturity offset.

Change of Direction Asymmetry in Youth Elite Tennis Players: A Longitudinal Study.

Longitudinal investigations into the development of inter-limb asymmetry in sports are scarce. This study examined the development of change of direction (COD) asymmetry magnitude in youth elite tennis players. Dominant (overall best performance) and non-dominant (best performance on the other side) scores and COD asymmetry magnitude were quantified annually (up to six years) in 323 male and 235 female players (ages 6 to13 years). Linear mixed effects regression models examined the development of COD performance and asymmetry magnitude according to players' chronological age and sex. Kappa coefficients examined the consistency for the direction of asymmetry across test occasions. Regardless of sex, COD performance significantly improved (p<0.001) while COD asymmetry magnitude significantly decreased (- 0.17±0.87% / year) with increasing chronological age. Regardless of age, males showed significantly lower COD times (- 0.111±0.091 s) and lower COD asymmetry magnitude (- 0.30±1.00%) compared to females. The slight and poor (k-value=0.02-0.00) kappa coefficients for males and females, respectively, highlight the direction specificity of functional asymmetry. These data show that whereas performance of the COD test improved, the magnitude of COD asymmetry declined across chronological age in youth tennis players.

Development of upper and lower extremity functional asymmetries in male and female elite youth tennis players: a longitudinal study.

BACKGROUND: This longitudinal study aimed to examine the development of both upper and lower extremity functional performances, together with asymmetry magnitudes and directionality in youth tennis players. METHODS: Dominant and non-dominant physical performance values of 90 players (53 males, 37 females) were determined yearly (with monitoring up to 3 years) using unilateral strength, power, speed and agility tests from which asymmetry magnitude percentages were calculated. Linear mixed effect models examined the development of performance values according to youth players' maturity offset, performance dominance, sex and training volume. Similarly, the development of functional asymmetry magnitudes was examined according to players' maturity offset, sex and training volume. Kappa coefficients (k) examined the consistency in directionality across test occasions. RESULTS: Regardless of sex, the dominant and non-dominant physical performance values of every test significantly (P<0.05) improved with increasing maturity offset. No sex differences were apparent except for strength and power related tests where male players performed significantly better. Functional asymmetry magnitudes (ranging from 2.0 to 15.9%) did not significantly change with increasing maturity offset (range=-0.3-0.4% per year). Training volume was not significantly associated with the performance values and asymmetry magnitudes. The dominant upper extremity (which holds the tennis racket) consistently displayed the dominant performance value (k value: 1.00) across test occasions, which was not the case at lower extremity level (k value range: -0.28-0.31). CONCLUSIONS: The functional asymmetry magnitudes did not change significantly with youth tennis players' maturity offset over a 3-year period.

Morphological and functional asymmetry in elite youth tennis players compared to sex- and age-matched controls.

Besides examining upper and lower limb morphological and functional asymmetry magnitudes, this study examined the relationship between lean mass and functional asymmetry in terms of magnitude and direction in 41 youth tennis players versus 41 controls. Asymmetry magnitude was determined using anthropometric measurements (circumferences, widths), bioelectrical impedance analysis (lean mass) and a test battery (handgrip strength, seated medicine ball throw, plate tapping, single leg countermovement jump, single leg forward hop test, 6 m single leg hop test, 505 change of direction). ANOVAs compared the dominant (overall highest/best value) against the non-dominant (highest/best value of opposing limb) result. Linear regressions explored the relationship between lean mass and functional asymmetry magnitudes. Kappa coefficients examined asymmetry direction consistency between the limb displaying the highest lean mass value and the limb performing dominantly across tests. Significant asymmetry magnitudes (p < 0.05) were found for all upper and lower limb outcome measures. No significant relationship was apparent between lean mass and functional asymmetry magnitude (r-value = -0.283-0.262). Despite finding (almost) perfect consistency in asymmetry direction (k-value = 0.84-1.00) for the upper limb, poor to slight consistency (k-value = -0.03-0.15) was found for the lower limb. Therefore, lean mass and functional asymmetry should be examined independently.

International vs. national female tennis players: a comparison of upper and lower extremity functional asymmetries.

BACKGROUND: Asymmetries have been reported to negatively impact sport performance. This study examined the magnitude and direction of whole-body functional asymmetry in international versus national female tennis players. METHODS: Ten internationally and twelve nationally ranked tennis players participated. Upper extremity functional asymmetries (or side-to-side performance differences) were evaluated using handgrip strength, seated shot-put throw and plate tapping. Lower extremity functional asymmetries were determined using the single leg countermovement jump, single leg forward hop test, 6 m single leg hop test, 505 changes of direction (time and deficit), and Y-balance test (anterior, posteromedial, posterolateral). ANOVAs were used to compare the dominant (overall best or fastest result of a specific test) versus non-dominant performance values (best or fastest result of the corresponding extremity) within the internationally versus nationally ranked players. Functional asymmetry magnitudes differences (expressed as a precentage) were examined using Mann-Whitney U tests. Kappa coefficients examined the consistency as to which extremity performed dominantly across tests. RESULTS: Significant asymmetries for every upper and lower extremity test were found. The functional asymmetry magnitude was significantly (P=0.020) higher on the single leg forward hop test for the nationally (6.3%) versus internationally ranked players (2.9%). Kappa coefficients showed perfect levels of consistency regarding all upper extremity tests (k=1.00), indicating true limb dominance whereas more variance was found as to which lower extremity performed dominantly across tests (k range=-0.067-0.174). CONCLUSIONS: The included female tennis players displayed significant whole-body functional asymmetries. Poor consistency as to which lower extremity performed dominantly across tests warrants individual asymmetry monitoring.

Bioelectrical impedance analysis as a means of quantifying upper and lower limb asymmetry in youth elite tennis players: An explorative study.

This study aimed to examine side-to-side differences in phase angle (PhA) in both upper and lower limbs of youth elite tennis players. Among other outcomes, PhA was directly determined using segmental multifrequency bioelectrical impedance analysis (BIA) in 26 tennis players (11.6 ± 1.1 years, 54% boys) and compared against a sex- and age-matched reference population. Significant upper limb asymmetry in PhA (p < 0.001), with a higher value on the dominant side of the body, was observed in the tennis players. At lower limb level, the tennis players showed a tendency towards a significantly higher PhA in the contralateral compared to the ipsilateral limb (p = 0.089). Using vector analysis (BIVA), a significant degree of PhA asymmetry (p = 0.002) was only reflected in the tennis players' upper limb. Additional segmental outcomes also demonstrated a significant degree of upper limb asymmetry in terms of tennis players' lean mass (p < 0.001), total segmental water (p < 0.001), fat mass (p < 0.001), extracellular water (p < 0.001) and extracellular water ratio (p < 0.001), whereas lower limb asymmetry was only observed in tennis players' fat mass (p = 0.037) and extracellular water (p = 0.001). This is the first study to report significantly more pronounced BIA-based side-to-side differences in youth elite tennis players compared to a non-athletic reference population at the upper limb level, whereas no significant between-group differences in the lower limbs were found. This explorative study should trigger future research to further scrutinize the role of BI(V)A as a promising field-method in monitoring bodily asymmetries in youth elite tennis players in view of sport performance and athletic health.HighlightsBioelectrical Impedance Analysis is a promising field-method to monitor side-to-side asymmetry in youth elite tennis players.Youth elite tennis players displayed a more pronounced degree of BIA-based side-to-side differences compared to a non-athletic reference population at the upper limb level, whereas whilst between-group differences appeared to be less evident in the lower limbs.Future research is warranted to scrutinize whether and to what extent these degrees of segmental bodily asymmetry may be related to injury risk (prevention) and athletic development of (pre)adolescent tennis players.

No Relationship between Lean Mass and Functional Asymmetry in High-Level Female Tennis Players.

The relationship between lean mass and functional asymmetry in terms of their magnitude and direction was examined in 22 high-level female tennis players (20.9 ± 3.6 years). Lean mass of both upper and lower extremities was examined using Dual X-ray Absorptiometry. Functional asymmetry was assessed using a battery of field tests (handgrip strength, seated shot-put throw, plate tapping, single leg countermovement jump, single leg forward hop test, 6 m single leg hop test, and 505 change of direction (time and deficit)). Paired sample t-tests compared the dominant (overall highest/best (performance) value) against the non-dominant value (highest/best (performance) value of the opposing extremity). Linear regressions were used to explore the relationship between lean mass and functional asymmetry magnitudes. Kappa coefficients were used to examine the consistency in direction between the extremity displaying the highest lean mass value and the extremity performing dominantly across tests. Significant asymmetry magnitudes (p < 0.05) were found for all upper and lower extremity lean mass and functional values. No relationship was apparent between lean mass and functional asymmetry magnitudes (p-value range = 0.131-0.889). Despite finding perfect consistency in asymmetry direction (k-value = 1.00) for the upper extremity, poor to fair consistency (k-value range = -0.00-0.21) was found for the lower extremity. In conclusion, lean mass and functional asymmetries should be examined independently.

Hydration Status in Adolescent Alpine Skiers During a Training Camp.

Maintaining euhydration is important for optimal health, performance and recovery, but can be challenging for alpine skiers when training in a relatively cold but dry environment. This study aimed to evaluate hydration status, fluid loss and fluid intake in adolescent alpine skiers during a training camp. Twelve athletes aged 14.3 ± 0.9 years volunteered to participate in the study. Athletes resided at an altitude of 1600 m and trained between 1614 and 2164 m. During eight consecutive days, urine specific gravity was measured before each morning training session using a refractometer. Changes in body weight representing fluid loss and ad libitum fluid intake during each morning training session were assessed using a precision scale. Mean pre-training urine specific gravity remained stable throughout the training camp. Individual values ranged between 1.010 and 1.028 g/cm3with 50 to 83% of athletes in a hypohydrated state (urine specific gravity ≥ 1.020 g/cm3). Mean training induced fluid loss remained stable throughout the training camp (range -420 to -587 g) with individual losses up to 1197 g (-3.5%). Fluid intake was significantly lower than fluid loss during each training session. To conclude, urine specific gravity values before training indicated insufficient daily fluid intake in more than half of the athletes. Furthermore, fluid intake during training in adolescent alpine skiers was suboptimal even when drinks were provided ad libitum. Coaches and athletes should be encouraged to carefully monitor hydration status and to ensure that alpine skiers drink sufficiently during and in between training sessions.

The Effect of a Tailored Intervention on Female Soccer Players' Hydration Status.

Numerous studies have reported that athletes' pre-training/-game hydration status is of concern. Up to now, only two cohort studies have examined the effect of an intervention aimed at improving pretraining/-game hydration status; however, without including a control group. Therefore, the aim of this quasi-experimental study was to examine whether and to what extent an individually tailored intervention focused on the benefits of being optimally hydrated before training or game would alter the hydration status of female soccer players. Two teams of young adult female soccer players were allocated to an intervention (n = 22; 19.8 ± 3.0 years) or a control group (n = 15; 22.8 ± 4.0 years). Players in the intervention group received an individually tailored intervention, based on Urine Specific Gravity (USG) measurements, which took place in between two training weeks. Before each training and match play, a urine sample was collected to determine players' hydration status. Mixed modelling was applied to assess within and between differences in hydration status over time. The pre-training/-game hydration status of the intervention group improved significantly, with players' mean USG-value decreasing from 1.013 ± 0.001 g/mL to 1.008 ± 0.002 g/mL (p = 0.005). In contrast, the mean USG-value in the control group increased significantly from 1.012 ± 0.002 g/mL to 1.016 ± 0.002 g/mL (p = 0.023), indicating a deterioration of their pre-training/-game hydration status. The individually tailored intervention did show a positive effect even though female soccer players in the present study were already reasonably well hydrated before the start of the intervention.

Whole-body morphological asymmetries in high-level female tennis players: A cross­sectional study.

This cross-sectional study aimed to examine the degree of whole-body morphological asymmetries in female tennis players. Data were collected in 19 high-level female tennis players (21.3 ± 3.4 years). Based on anthropometric measurements (upper arm, lower arm, wrist, upper leg and lower leg circumferences as well as elbow and knee widths) and dual x-ray absorptiometry research scans (bone mineral density (BMD), bone mineral content (BMC), lean mass (LM), fat mass (FM) as well as humerus, radio-ulnar, femur and tibia bone lengths), within-subject morphological asymmetries for both upper (dominant vs. non-dominant) and lower (contralateral vs. ipsilateral) extremities were examined. Upper arm (p = 0.015), lower arm (p < 0.001) and wrist circumferences (p < 0.001), elbow width (p = 0.049), BMD (p < 0.001), BMC (p < 0.001), LM (p = 0.001), humerus (p = 0.003) and radio-ulnar bone length (p < 0.001) were all greater in the dominant upper extremity. BMC (p < 0.001) and LM (p < 0.001) were greater in the contralateral lower extremity, whereas FM (p = 0.028) was greater in the ipsilateral lower extremity. This is the first study to report significant side-to-side differences in both upper and lower extremities in high-level female tennis players.

Changes in weight and body composition across five years at university: A prospective observational study.

OBJECTIVES: The transition from high school to college or university has been shown to be a critical period for weight and fat gain. To date, no European data on weight and fat gain over the full trajectory of college or university are available. Therefore, the purpose of the present study was to investigate weight and fat gain among Belgian university students from freshman through senior year of university. METHODS: In this prospective observational study, a total of 340 university students were measured six times, i.e. at baseline (start of the first academic year) and at the start of the second semester of the first, second, third, fourth and fifth academic year. Objective measurements included body weight, height, body mass index (BMI), fat%, fat mass, fat free mass and waist circumference. Multilevel modelling was used to assess anthropometric changes over time according to sex. RESULTS: From freshman through senior year of university, individual weight changes ranged from -5.2 to +15.7kg, and respectively 77.4% and 69.3% of students showed increases in BMI and fat%. Stronger increases in weight and BMI were found for males (5.7kg; 1.6kg/m2; both p<0.001) than females (2.2kg; 0.8kg/m2; both p<0.001) over the 4.5 year measuring period. Similarly, waist circumference increased more in males (4.7cm; p<0.001) than in females (1.0cm; p<0.001). In contrast, females (2.5%; p<0.001) showed a higher increase in fat% than males (1.0%; p = 0.019). Across sexes, the highest weight and fat gains were found during the first semester and during the final year of university. CONCLUSIONS: Belgian university students gain a significant amount of body weight and body fat from freshman through senior year of university. Similar to the first semester, more pronounced increases in weight and fat were observed during the final year of university. Interventions aiming at preventing weight gain at university should not only focus on freshmen but also on senior students.

Upper extremity bone mineral content asymmetries in tennis players: A systematic review and meta-analysis.

The aim of this study was to examine the magnitude of upper extremity bone mineral content (BMC) asymmetries in tennis players. Furthermore, the influence of sex (male versus female versus mixed), chronological age (juniors: < 18 years; adults: 18-39 years and seniors: ≥ 40 years) and starting age (early starters: < 14 years and late starters: > 18 years) on these asymmetries were examined. Two databases were searched for scientific articles that examined upper extremity BMC in tennis players. Pooling of the individual study effect sizes was conducted using the random-effects model. Three subgroup analyses were performed based on sex, chronological age and starting age. Out of the 15 included studies 24 effect sizes were extracted resulting in a significant difference in BMC value between the dominant and nondominant upper extremity of the tennis players (Standardised Mean Difference: 0.85 [95% CI: 0.67-1.03]). The three subgroup analyses all showed medium to strong effect sizes and significant intergroup differences. To conclude, BMC was significantly higher in the dominant upper extremity compared to the nondominant upper extremity in tennis players. Nevertheless, the influence of training volume and playing experience on these asymmetries are yet to be examined.

The hydration status of young female elite soccer players during an official tournament.

BACKGROUND: The hydration status of elite female soccer players is a concern, especially during high-volume training periods or tournaments. Furthermore, scientific literature on this topic is scarce to non-existent. Therefore, the primary aim of this study was to evaluate the hydration status in elite youth female soccer players during an official tournament. The secondary aim was to identify a possible relationship between pre-training hydration status and fluid intake. METHODS: Eighteen players were followed during eight consecutive days. Urine specific gravity was used to assess hydration status. Body weight was monitored before and after every training and match, whilst individual fluid intake was only registered during training. The players were informed about their hydration status on day 5. RESULTS: On days 1 to 4, the percentage of players who were at least minimally hypohydrated ranged between 44% and 78%. On day 5 (rest day), all the players were at least minimally hypohydrated. After the information session on day 5, the relative number of euhydrated players increased to 89% on both day 6 (training day) and day 7 (match day). On the final day (rest day), all players were either minimally hypohydrated or hypohydrated. Furthermore, a moderate and significant negative correlation (r=-0.44; N.=54; P=0.01) was found between fluid intake during and USG value before the training sessions. CONCLUSIONS: The data illustrates that the hydration status of this population of elite youth female soccer players may be suboptimal and is of substantial concern on rest days during this tournament under temperate conditions. Receiving personal advice about rehydration seems to have a positive effect.