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Context: Although balance is generally recognized to be an important feature in ensuring good performance in soccer, its link with functional performance remains mostly unexplored, especially in young athletes.Objective: To investigate changes in balance induced by fatigue for unipedal and bipedal static stances in young soccer players.Design: Crossover study. Setting: Biomechanics laboratory and outdoor soccer field.Patients or Other Participants: Twenty-one male soccer players (age ¼ 14.5 6 0.2 years, height ¼ 164.5 6 5.6 cm, mass ¼ 56.8 6 6.8 kg).Intervention(s): Static balance was assessed with posturalsway analysis in unipedal and bipedal upright stance before and after a fatigue protocol consisting of a repeated sprint ability (RSA) test (2 3 15-m shuttle sprint interspersed with 20 seconds of passive recovery, repeated 6 times).Main Outcome Measure(s): On the basis of the center-ofpressure (COP) time series acquired during the experimental tests, we measured sway area, COP path length, and COP maximum displacement and velocity in the anteroposterior and mediolateral directions. Results:Fatigue increased all sway values in bipedal stance and all values except COP velocity in the mediolateral direction in unipedal stance. Fatigue index (calculated on the basis of RSA performance) was positively correlated with fatigue/rest sway ratio for COP path length and COP velocity in the anteroposterior and mediolateral directions for nondominant single-legged stance.Conclusions: Fatigued players exhibited reduced performance of the postural-control system. Participants with better performance in the RSA test appeared less affected by balance impairment, especially in single-legged stance.Key Words: postural sway, repeated sprint ability test, athletes Key PointsIn young soccer players, balance was adversely affected by fatigue. A moderate correlation existed between balance impairment and repeated sprint ability performance.

In this study, we investigated the static balance of adult and adolescent elite soccer players to understand how expertise and playing position influence postural control. Seventy-one national level players were tested using a force platform to acquire Center-of-Pressure (COP) data in uni- and bipedal stance and calculate sway area (SA), COP path length, velocity and displacements. The results show significant differences in postural sway related to age and playing position only for single-limb stance. In particular, midfielders exhibited significantly lower values of SA with respect to defenders (-48%, p = 0.001) and the under-15 players exhibited SA 42-64% higher than all the others (p = 0.001). In the light of planning training or rehabilitation programs specific for each player's role and age, sway measurements may supply useful, objective and reliable information only for the unipedal test as the bipedal standing appears not challenging enough to let differences in balance abilities emerge.

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The aim of this study was to assess the effects of vigorous exercise on functional abilities by means of a Senior Fitness Test (SFT) in a group of elderly adults. Twenty healthy and inactive people performed vigorous exercise (VE: 12 men and 8 women, aged 69.6 ± 3.9 years). At the beginning of the study (T0) and after 3 months (T1), each subject's functional ability was tested for muscular strength, agility, cardiovascular fitness, flexibility, and balance. The VE was designed with continuous and interval exercise involving large muscle activities. Functional exercises were performed between 60% and 84% of heart rate reserve (HRR) for a duration of 65 minutes. Five out of the 6 SFTs performed were found significantly improved: Chair Stand (T0 12.4 ± 2.4, T1 13.5 ± 2.6, p < 0.01), Arm Curl (T0 14.2 ± 3.6, T1 16.6 ± 3.6, p < 0.01), 2 min step (T0 98.2 ± 15.7, T1 108.9 ± 16.2, p < 0.01), Chair Sit-and-Reach (T0 −9.9 ± 7.7 cm, T1 1.7 ± 6.3 cm, p < 0.01), and Back Scratch (T0 −15.8 ± 10.9 cm, T1 −8.4 ± 13.1 cm, p < 0.01). Our results suggest that a high intensity protocol and functional exercises can improve functional mobility and muscle endurance in those over 65 years of age. SFTs are an effective method for assessing improvements in the functional capacity of elderly adults.

Insulin sensitivity (Si), glucose tolerance, and lipid metabolism were investigated in osteopenic postmenopausal women before and after 6 months of treatment with raloxifene (60 mg/d) or placebo. In a group of women (n = 34), glucose metabolism was evaluated by means of an oral glucose tolerance test (75 g). In another group of women (n = 24), Si and peripheral glucose utilization not dependent on insulin were evaluated by means of a frequently sampled iv glucose tolerance test associated with the minimal model method. No metabolic modification was observed in women receiving placebo. Raloxifene did not significantly modify high density lipoprotein-cholesterol and triglycerides, whereas it significantly decreased low density lipoprotein (LDL) cholesterol (4.84 +/- 0.34 mmol/liter vs. 3.83 +/- 0.49 mmol/liter; P = 0.014) and LDL/high density lipoprotein cholesterol ratio (3.21 +/- 0.31 mmol/liter vs. 2.46 +/- 0.44 mmol/liter; P = 0.012). Fasting levels and responses to the oral glucose tolerance test of glucose, insulin, C-peptide, and C-peptide/insulin were not modified by raloxifene. Similarly, raloxifene did not modify Si (4.22 +/- 4.1 vs. 5.13 +/- 1.75), or insulin (0.025 +/- 0.003 vs. 0.019 +/- 0.002). The present data show that in osteopenic postmenopausal women raloxifene reduces LDL levels but does not modify insulin sensitivity and glucose metabolism.

The aim of this study was to investigate the acute effects of whole-body vibration (WBV) on Repeated Sprint Ability (RSA). Seventeen male soccer players (16.71±0.47 y) performed three RSA tests (Randomized crossover study design). The second RSA test was done with WBV (RSA2) to assess the effect of WBV. The studied variables were: best time (BT), worst time (WT), total time (TT), the fatigue index (FI) of RSA, and post-test blood lactate (BLa). ANOVA with repeated measures showed no differences between RSA1 and RSA3, while there were significant differences in all variables studied. TT= [RSA2 0.93% and 1.68% lower than RSA1 and RSA3 respectively; individual sprints, WBV showed a significant effect at the 5 st sprint: RSA2 2.29% and 2.95% lower than RSA1 and RSA3 respectively (p<0.005), while at the 6 st sprint: RSA2 2.75% and 4.09% lower than RSA1 and RSA3 respectively; p<0.005. In conclusion, when applying WBV during the recovery periods of Repeated Sprint Ability efforts, most of the performance variables improved.

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