Jan Bourgois

A multidisciplinary selection model for youth soccer: the Ghent Youth Soccer Project

Objectives: To determine the relationships between physical and performance characteristics and level of skill in youth soccer players aged 12–16 years. Methods: Anthropometry, maturity status, functional and sport-specific parameters were assessed in elite, sub-elite, and non-elite youth players in four age groups: U13 (n = 117), U14 (n = 136), U15 (n = 138) and U16 (n = 99). Results: Multivariate analyses of covariance by age group with maturity status as the covariate showed that elite players scored better than the non-elite players on strength, flexibility, speed, aerobic endurance, anaerobic capacity and several technical skills (p<0.05). Stepwise discriminant analyses showed that running speed and technical skills were the most important characteristics in U13 and U14 players, while cardiorespiratory endurance was more important in U15 and U16 players. The results suggest that discriminating characteristics change with competitive age levels. Conclusions: Characteristics that discriminate youth soccer players vary by age group. Talent identification models should thus be dynamic and provide opportunities for changing parameters in a long-term developmental context.

Effects of three different training modalities on the cross sectional area of the lumbar multifidus muscle in patients with chronic low back pain

Objectives—To determine the effect of different training schedules on the cross sectional area (CSA) of the lumbar multifidus muscle in patients with chronic low back pain. Methods—Each of 59 nine patients was randomly assigned to one of three programmes: 10 weeks of stabilisation training (group 1; n = 19); 10 weeks of stabilisation training combined with dynamic resistance training (group 2; n = 20); 10 weeks of stabilisation training combined with dynamic-static resistance training (group 3; n = 20). Before and after 10 weeks of training, multifidus CSAs were measured from standard computed tomography images at three different levels (upper end plate of L3 and L4, and lower end plate of L4). Results—The CSA of the multifidus muscle was significantly increased at all levels after training in group 3. In contrast, no significant differences were found in groups 1 and 2. Conclusions—General stabilisation exercises and dynamic intensive lumbar resistance training have no significant effect on the CSA of the lumbar multifidus muscle in patients with chronic low back pain. The static holding component between the concentric and eccentric phase was found to be critical in inducing muscle hypertrophy during the first 10 weeks. Treatment consisting of stabilisation training combined with an intensive lumbar dynamic-static strengthening programme seems to be the most appropriate method of restoring the size of the multifidus muscle.

Important role of muscle carnosine in rowing performance

The role of the presence of carnosine (β-alanyl-L-histidine) in millimolar concentrations in human skeletal muscle is poorly understood. Chronic oral β-alanine supplementation is shown to elevate muscle carnosine content and improve anaerobic exercise performance during some laboratory tests, mainly in the untrained. It remains to be determined whether carnosine loading can improve single competition-like events in elite athletes. The aims of the present study were to investigate if performance is related to the muscle carnosine content and if β-alanine supplementation improves performance in highly trained rowers. Eighteen Belgian elite rowers were supplemented for 7 wk with either placebo or β-alanine (5 g/day). Before and following supplementation, muscle carnosine content in soleus and gastrocnemius medialis was measured by proton magnetic resonance spectroscopy ((1)H-MRS) and the performance was evaluated in a 2,000-m ergometer test. At baseline, there was a strong positive correlation between 100-, 500-, 2,000-, and 6,000-m speed and muscle carnosine content. After β-alanine supplementation, the carnosine content increased by 45.3% in soleus and 28.2% in gastrocnemius. Following supplementation, the β-alanine group was 4.3 s faster than the placebo group, whereas before supplementation they were 0.3 s slower (P = 0.07). Muscle carnosine elevation was positively correlated to 2,000-m performance enhancement (P = 0.042 and r = 0.498). It can be concluded that the positive correlation between baseline muscle carnosine levels and rowing performance and the positive correlation between changes in muscle carnosine and performance improvement suggest that muscle carnosine is a new determinant of rowing performance.

The Physical Performance Test as a predictor of frequent fallers: a prospective community-based cohort study

Objective: To construct a risk model in order to identify elderly individuals at risk of frequent falling. Design: Prospective community-based cohort study over 12 months. Setting: Baseline measures were performed at a local community centre. Subjects: Two hundred and sixty-three community-dwelling elderly people (mean age 72 years). Measurements: A variety of variables were evaluated, including medical, psychological, sensory, physical and postural control measurements. Fall incidence was monitored retrospectively and during one-year follow-up. Results: Logistic regression analysis showed that polypharmacia was the most prominent medical fall predictor with an odds ratio (OR) of 1.29 (P =0.005), poor visual acuity the best sensory predictor (OR=0.84; P =0.009) and general fear of falling the most crucial psychological predictor (OR=3.25; P B=0.001). Increased postural sway in near-tandem stance with eyes open was selected as the best balance predictor for falls (OR=5.60; P =0.010), followed by delayed anteroposterior movement velocity during rhythmic weight shifts (OR=0.42; P =0.004). The best physical predictor was a low score on the Physical Performance Test (OR=4.16; P <0.001), followed by decreased maximal handgrip strength (OR=0.87; P <0.001) and increased timed chair-stands (OR=1.13; P <0.003). Step-by-step regression analysis revealed a risk model for the prediction of future falls, as a combination of the Physical Performance Test and maximal handgrip strength. Conclusion: This study confirms the multicausality of falls, since medical, psychological, sensory, postural control as well as physical variables provides a predictive value. The composed fall risk model was mainly physically oriented.

The effects of three different training modalities on the cross-sectional area of the paravertebral muscles.

The purpose of this study was to determine the effect of different training schedules on the cross‐sectional area (CSA) of the paravertebral muscles (PA) in chronic low back pain (CLBP) patients. To achieve this goal 59 patients were randomly assigned to three different 10‐week rehabilitation programs: stabilization training (group 1, n=19), stabilization training combined with dynamic resistance training (group 2, n=20) and stabilization training combined with dynamic‐static resistance training (group 3, n=20). The CSA of the PA was derived from standard computerized tomography (CT) images at three different levels. The CSA of the PA was found to increase statistically in group 2 (upper end‐plate of L4) and group 3 (upper end‐plate of L3 and lower end‐plate of L4). In contrast, no statistical differences over time were found in group 1. Since stabilization exercises have no effect on the CSA of the PA, intensive lumbar resistance training seems to be necessary to restore the size of the PA in CLBP patients with atrophied back muscles. No systematic difference in hypertrophy between dynamic and dynamic‐static strengthening training modes was found.

Bradycardia, ventricular pauses, syncope, and sports

16 athletic patients were examined because of syncope, Stokes-Adams attacks, or both. The life-threatening condition required pacemaker implantation in 7 patients. 8 of the 9 other subjects became symptom-free after stopping heavy physical training. 37 top-ranking athletes underwent 24 h Holter monitoring. Pauses longer than 2 s occurred in 19% and resulted from sinus arrest. The longest pause lasted 2.5 s. Second-degree atrioventricular block was noted in 13%.

Physical fitness of elite Belgian soccer players by player position.

Abstract Boone, J, Vaeyens, R, Steyaert, A, Vanden Bossche, L, and Bourgois, J. Physical fitness of elite Belgian soccer players by player position. J Strength Cond Res 26(8): 2051–2057, 2012—The purpose of this study was to gain an insight into the physical and physiological profile of elite Belgian soccer players with specific regard to the players position on the field. The sample consisted of 289 adult players from 6 different first division teams. The players were divided into 5 subgroups (goalkeepers, center backs, full backs, midfielders, and strikers) according to their self-reported best position on the field. The subjects performed anaerobic (10-m sprint, 5 × 10-m shuttle run [SR], squat jump [SJ], and countermovement jump [CMJ]) and aerobic (incremental running protocol) laboratory tests. The strikers had significantly shorter sprinting times (5-, 5- to 10-m time, and SR) compared with the midfielders, center backs, and goalkeepers, whereas the full backs were also significantly faster compared with the goalkeepers and the center backs. The goalkeepers and the center backs displayed higher jumping heights (total mean SJ = 40.7 ± 4.6 cm and CMJ = 43.1 ± 4.9 cm) compared with the other 3 positions, whereas the strikers also jumped higher than the full backs and the midfielders did. Regarding the aerobic performance, both full backs and the midfielders (61.2 ± 2.7 and 60.4 ± 2.8 ml·min−1·kg−1, respectively) had a higher V[Combining Dot Above]O2max compared with the strikers, center backs, and goalkeepers (56.8 ± 3.1, 55.6 ± 3.5, and 52.1 ± 5.0 ml·min−1·kg−1, respectively). From this study, it could be concluded that players in different positions have different physiological characteristics. The results of this study might provide useful insights for individualized conditional training programs for soccer players. Aside from the predominant technical and tactical skills, a physical profile that is well adjusted to the position on the field might enhance game performance.

A home-based multidimensional exercise program reduced physical impairment and fear of falling.

Abstract Objective. To investigate the efficacy of a guided and graded home-based exercise program for improving a range of physical outcomes in older people. Design. Controlled clinical trial of 16 weeks Setting. Two geographical areas in Gent, Belgium Participants. 66 independent-living older people (age: 71-98) with a history of falls and moderate physical impairment Intervention. Twenty-four 30-minute training sessions were given by a trained physiotherapist over a period of 16 weeks in the participant’s home. Different types of exercises on balance, aerobic performance, flexibility, and muscle strength were provided. Main outcome measures. Muscle strength, static and dynamic balance, aerobic performance, activities in daily living, fear of falling and avoidance of daily activities were assessed at baseline and after 16 weeks intervention. Results: At baseline, there were no significant differences in the measured variables between exercise and control groups. After 16 weeks, the exercise group showed significantly improved ankle muscle strength, balance performance and aerobic capacity, and decreased fear of falling, dependency in daily activities and avoidance of daily activities compared to the control group. The improvements in knee muscle strength, timed chair stands, and functional reach were not significant. Conclusion: The home-based, individualized exercise program was effective in reducing several physical factors associated with falls in community-dwelling older people with moderate physical impairment. The decrease in fear of falling and other behavioural variables needs to be considered with care and needs further investigation.

Metabolic and cardiorespiratory responses in young oarsmen during prolonged exercise tests on a rowing ergometer at power outputs corresponding to two concepts of anaerobic threshold

Abstract A group of ten young experienced oarsmen [mean age 17.5 (SD 1.7) years, height 182.5 (SD 5.9) cm, body mass 77.0 (SEM 10.6) kg] exercised in a progressive incremental test (PIE: 50W · 3 min−1) on a rowing ergometer to determine the power output corresponding to the 4 mmol lactate · l−1 anaerobic threshold (AT4) and the individual anaerobic threshold (IAT). Within 10 days they performed at random two 30-min prolonged exercise tests (PET) at power outputs corresponding to AT4 and IAT to demonstrate whether or not a steady-state blood lactate concentration [La−]b could be maintained. Oxygen uptake (V˙O2), heart rate (HR) and [La−]b were measured. The PIE revealed significant lower values at IAT compared to AT4 for power output (P < 0.01), HR (P < 0.01) and V˙O2 (P < 0.01). Coefficients of correlation between AT4 and IAT were 0.68 for power output, 0.79 for HR and 0.70 for V˙O2. All the subjects could complete the PET at IAT and only six out of the ten at AT4. The [La−]b at the end of PET was significantly higher at AT4 compared to IAT (P < 0.01). Similar results were found for V˙O2 (P < 0.01) and for HR (P < 0.01). A steady state of mean blood lactate concentration ([La−]ss was found only for the power output at IAT. From the results of this study, we concluded that both concepts of anaerobic threshold gave different information about submaximal endurance capacity. Only IAT represented on average [La−]ss. It is suggested that more research is needed to elicit optimal guidelines for the intensity of endurance training.

Motor competence assessment in children: Convergent and discriminant validity between the BOT-2 Short Form and KTK testing batteries

This study investigated convergent and discriminant validity between two motor competence assessment instruments in 2485 Flemish children: the Bruininks-Oseretsky Test of Motor Proficiency 2 Short Form (BOT-2 Short Form) and the KörperKoördinationsTest für Kinder (KTK). A Pearson correlation assessed the relationship between BOT-2 Short Form total, gross and fine motor composite scores and KTK Motor Quotient in three age cohorts (6-7, 8-9, 10-11 years). Crosstabs were used to measure agreement in classification in children scoring below percentile 5 and 15 and above percentile 85 and 95. Moderately strong positive (r=0.44-0.64) associations between BOT-2 total and gross motor composite scores and KTK Motor Quotient and weak positive correlations between BOT-2 Short Form fine motor composite and KTK Motor Quotient scores (r=0.25-0.37) were found. Levels of agreement were fair to moderate. Therefore, some proof of convergent and discriminant validity between BOT-2 Short Form and KTK was established in this study, underlining the notion that the evaluation of motor competence should not be based upon a single assessment instrument.