Muscle Fibre Typology as a Novel Risk Factor for Hamstring Strain Injuries in Professional Football (Soccer): A Prospective Cohort Study.

BACKGROUND: Hamstring strain injuries (HSI) are prevalent in team sports and occur frequently in the later phase of matches. In the search for interindividual factors that determine muscle fatigue and possibly injury risk, muscle fibre typology is a likely candidate. OBJECTIVE: The aim of the study was to determine whether muscle fibre typology is a risk factor for HSI. METHODS: A prospective cohort study was conducted over three seasons in professional football players competing in the Belgian Jupiler Pro League (n = 118) and in the English Premier League (n = 47). A total of 27 HSI were sustained during this period. Muscle fibre typology was non-invasively estimated using proton magnetic resonance spectroscopy and was characterized as a fast, slow, or intermediate typology based on the carnosine concentration in the soleus. A multivariate Cox model was used to identify risk factors for HSI. RESULTS: Football players exhibited a wide variety of muscle typologies (slow 44.9%, intermediate 39.8%, fast 15.3%). In the combined cohort, players with a fast typology displayed a 5.3-fold (95% confidence interval [CI] 1.92-14.8; P = 0.001) higher risk of sustaining an index HSI than slow typology players. This was also independently observed in both leagues separately as, respectively, a 6.7-fold (95% CI 1.3-34.1; P = 0.023) and a 5.1-fold (95% CI 1.2-20.4; P = 0.023) higher chance was found in fast typology players than in slow typology players of the Jupiler Pro League and the Premier League cohort. CONCLUSION: We identified muscle fibre typology as a novel and potent risk factor for HSI in team sports.

Longitudinal Development of Explosive Leg Power from Childhood to Adulthood in Soccer Players.

The aim of the this study was to investigate the development of explosive leg power by using 2 similar jumping protocols (countermovement jump and standing broad jump) in 555 Belgian, high-level young soccer players, aged between 7 and 20 years. The total sample was divided into 3 longitudinal samples related to growth and maturation (pre-teenchildhood: (6-10 years;), early adolescence: (11-16 years;) and late adolescence: (17-20 years)), and 6 multilevel regression models were obtained. Generally, both jumping protocols emphasized that chronological age, body size dimensions (by means of fat mass in the late childhood and early adolescence groups, fat-free mass in the late adolescence group and stature--(not for CMJ in late childhood group) and fat mass in the late childhood and early adolescence groups, and fat-free mass in the late adolescence group) and motor coordination (one item of a 3-component test battery) are longitudinal predictors of explosive leg power from childhood to young adulthood. The contribution of maturational status was not investigated in this study. The present findings highlight the importance of including non-specific motor coordination in soccer talent development programs.

The Yo-Yo intermittent recovery test level 1 is reliable in young high-level soccer players.

The aim of the study was to investigate test reliability of the Yo-Yo intermittent recovery test level 1 (YYIR1) in 36 high-level youth soccer players, aged between 13 and 18 years. Players were divided into three age groups (U15, U17 and U19) and completed three YYIR1 in three consecutive weeks. Pairwise comparisons were used to investigate test reliability (for distances and heart rate responses) using technical error (TE), coefficient of variation (CV), intra-class correlation (ICC) and limits of agreement (LOA) with Bland-Altman plots. The mean YYIR1 distances for the U15, U17 and U19 groups were 2024 ± 470 m, 2404 ± 347 m and 2547 ± 337 m, respectively. The results revealed that the TEs varied between 74 and 172 m, CVs between 3.0 and 7.5%, and ICCs between 0.87 and 0.95 across all age groups for the YYIR1 distance. For heart rate responses, the TEs varied between 1 and 6 bpm, CVs between 0.7 and 4.8%, and ICCs between 0.73 and 0.97. The small ratio LOA revealed that any two YYIR1 performances in one week will not differ by more than 9 to 28% due to measurement error. In summary, the YYIR1 performance and the physiological responses have proven to be highly reliable in a sample of Belgian high-level youth soccer players, aged between 13 and 18 years. The demonstrated high level of intermittent endurance capacity in all age groups may be used for comparison of other prospective young soccer players.

Relative age, biological maturation and anaerobic characteristics in elite youth soccer players.

Being relatively older and having an advanced biological maturation status have been associated with increased likelihood of selection in young elite soccer players. The aims of the study were to investigate the presence of a relative age effect (RAE) and the influence of birth quarter on anthropometry, biological maturity and anaerobic parameters in 374 elite Belgian youth soccer players. The sample was divided into 3 age groups, each subdivided into 4 birth quarters (BQ). Players had their APHV estimated and height, weight, SBJ, CMJ, sprint 5 and 30 m were assessed. Overall, more players were born in BQ1 (42.3%) compared with players born in BQ4 (13.7%). Further, MANCOVA revealed no differences in all parameters between the 4 BQ's, controlled for age and APHV. These results suggest that relatively youngest players can offset the RAE if they enter puberty earlier. Furthermore, the results demonstrated possible differences between BQ1 and BQ4, suggesting that caution is necessary when estimating differences between players because of large discrepancies between statistical and practical significance. These findings also show that coaches should develop realistic expectations of the physical abilities of younger players and these expectations should be made in the context of biological characteristics rather than chronological age-based standards.

Relative age effect and Yo-Yo IR1 in youth soccer.

The aims of the study were to investigate the presence of a relative age effect and the influence of birth quarter on anthropometric characteristics, an estimation of biological maturity and performance in the Yo-Yo Intermittent Recovery Test level 1 in 606 elite, Flemish youth soccer players. The sample was divided into 5 chronological age groups (U10-U19), each subdivided into 4 birth quarters. Players had their APHV estimated and height, weight and Yo-Yo IR1 performance were assessed. Differences between quarters were investigated using uni- and multivariate analyses. Overall, significantly (P<0.001) more players were born in the first quarter (37.6%) compared to the last (13.2%). Further, no significant differences in anthropometric variables and Yo-Yo IR1 performance were found between the 4 birth quarters. However, there was a trend for players born in the first quarter being taller and heavier than players born in the fourth quarter. Players born in the last quarter tended to experience their peak in growth earlier, this may have enabled them to compete physically with their relatively older peers. Our results indicated selection procedures which are focused on the formation of strong physical and physiological homogeneous groups. Relative age and individual biological maturation should be considered when selecting adolescent soccer players.

Which bioequivalence study for a racemic drug? Application to milnacipran.

Milnacipran, a new non tricyclic antidepressant drug, is a racemic mixture (F2207) composed of two enantiomers: F2695 and F2696, both demonstrated to be active. A randomized open label, single-dose latin square study was undertaken in 24 healthy volunteers to compare, based on racemate data, the relative bioavailability of two new formulations to that of a reference formulation. Later on, as suggested by actual regulatory trend, analysis was carried out on enantiomer data, although in a supportive way. Bioequivalence was assessed on calculation of 90% confidence intervals for log-transformed Cmax and AUC(0-infinity) and on Wilcoxon test for Tmax with a 5% level of significance. Based on racemate data, both test formulations were demonstrated to be equivalent to the reference capsule in terms of Cmax and AUC-(0-infinity). Differences in Tmax reached statistical significance, although their mean magnitude was small, and probably not relevant when related to antidepressant long-term therapy. When considering the test capsule - reference capsule comparison, the equivalence demonstrated for the racemate reflect that of each enantiomer. On the contrary, equivalence between the test tablet and the reference capsule demonstrated for the racemate, is not supported by both enantiomers as Cmax of F2696 fails to reach bioequivalence criteria, making more uncertain the conclusion of bioequivalence. From this experience, it seems than when equivalence is demonstrated close to the limits for the racemate, it is difficult, especially for a low variability drug such as milnacipran, to comply with equivalence criteria for both enantiomers.

Pharmacokinetics of milnacipran in liver impairment.

The pharmacokinetics of single 50 mg oral and intravenous doses of milnacipran, a new non tricyclic antidepressant drug, were compared in 11 chronic liver impaired (LI) subjects and in 6 control subjects. Hepatic impairments, classified according to the PUGH scale were moderate (1 grade A), intermediate (6 grade B) and severe (4 grade C). Concentrations of unchanged drug and its conjugated form (its main metabolite) were measured in plasma and urines. In control subjects, milnacipran present high absolute bioavailability (mean value of 90%). Around 50% of the dose are excreted in urines as unchanged, while around 14% are excreted as glucuroconjugate. The remaining is composed of free and conjugated phase I inactive metabolites. Administration of milnacipran in LI subjects results in non significant changes in its pharmacokinetics, although its variability is increased. Unchanged drug exposure is not modified in LI subjects, while plasma levels of the conjugate are slightly decreased compared to the control group. This could either be due to a slight reduction in the conjugation process, or to a change in the distribution of the drug as urine excretion of both unchanged and conjugated forms are not modified compared to the control group. A few LI subjects present supra-bioavailability resulting in higher drug exposure after oral administration than after intravenous infusion. These modifications are not clinically relevant as drug exposure of the parent drug is not modified. As the unchanged drug is the only compound responsible for the activity of milnacipran, no dosage adjustment is needed in patients presenting liver impairment.

Pharmacokinetics of milnacipran in renal impairment.

The pharmacokinetics of a single 50 mg dose of milnacipran, a new non tricyclic antidepressant drug, were compared in 8 chronic renal failure subjects (Clc(reat) between 9 to 84.5 ml.min(-1)) and in 6 healthy volunteers. Concentrations of unchanged (F2207 racemate and F2695 and F2696, enantiomers) and glucuroconjugated drug (main metabolite) were measured using HPLC and GC-MS. As for drugs mainly eliminated via renal route, the pharmacokinetics of milnacipran were markedly affected by impaired renal function with the elimination half-life of severely impaired subject being approximately three times that of the control group. Milnacipran apparent total clearance and renal clearance were positively correlated with glomerular filtration rate, while non-renal clearance and apparent volume of distribution were unaffected by renal impairment. Plasma concentrations of the glucuroconjugate were gradually increased in plasma, while its total urine excretion remained unchanged. As for the racemate, pharmacokinetics of each enantiomer were modified by renal failure, although, as predictable from its higher renal clearance value, it was more marked for F2696 than for F2695. Considering that modifications were shown to be proportional to the degree of renal impairment and that milnacipran presents low variability, the necessary dose adjustment is therefore easy to predict.

Validity of N-acetyl-beta-D-glucosaminidase (NAG) determination in assessing netilmicin nephrotoxicity in preterm babies.

The supposed nephrotoxicity of netilmicin has been assessed in preterm neonates using the urinary excretion of a lysosomal enzyme as marker: N-acetyl-beta-D-glucosaminidase (NAG). 17 male preterm neonates with birth weight appropriate for gestational age were enrolled in a study where 9 received netilmicin therapy since the first day of life and 8 served as control group. We observed a significant increase in urinary NAG/creatinine ratio during the postnatal days in the netilmicin group babies followed by a regular decrease during the days after the end of therapy. If this increase in lysosomal enzymuria such as NAG could reflect netilmicin nephrotoxicity on the proximal tubular cell, many questions remain unanswered about the exact significance of this finding. In particular, its relation with tubular cell dysfunction remains to be established.

[Treatment of AL amyloidosis without myeloma]. / Traitement de l'amylose AL sans myélome.

AL amyloidosis is a serious complication of monoclonal gammopathy. The therapeutic strategy in amyloidosis associated with myeloma is to decrease the amyloidogenic precursor synthetised by the monoclonal plasmocytic proliferation. However, when systemic amyloidosis complicates a so called "benign" monoclonal gammopathy, this therapeutic approach is debatable. We report 10 cases of AL amyloidosis without myeloma treated by chemotherapy. Eight patients were initially given alkylating agents (cyclophosphamide or melphalan) which had no effect on the clinical progression of their systemic amyloidosis or on the plasma concentrations of the precursor. A limited open clinical trial including 4 patients was then undertaken based on the Vincristine, Adriamycine, Dexamethasone combination recently proposed for cases of resistant myeloma. A 50% reduction in the serum monoclonal protein was observed in 2 patients with this treatment. However, the mean survival of the 10 patients (25 months) was not longer than that previously reported for patients receiving more conventional treatment. The results of this limited trial indicate the need for further controlled therapeutic trials with larger numbers of patients in order to assess the effect of polychemotherapy in patients with AL amyloidosis.

Focal glomerulosclerosis associated with Charcot-Marie-Tooth disease.

This report describes a new case of the rare association of focal glomerulosclerosis with a peroneal muscular atrophy of the Charcot-Marie-Tooth type. The young patient was admitted with a nephrotic syndrome. A terminal renal failure rapidly developed. Numerous chronic nephropathies were known in the patient's family. The ultrastructural study of the renal biopsy revealed a focal fusion of the epithelial foot processes, thickened and pleated mesangial basal laminae, vacuolated podocytes and small intranuclear clear inclusions. The Charcot-Marie-Tooth disease was of the hypertrophic type. According to a review of the literature and to further information concerning the follow-up of the 5 previously reported cases, the prognosis of the nephropathy is guarded with progression to end-stage renal disease in a few years. This case represents the 6th reported case of focal glomerulosclerosis associated with Charcot-Marie-Tooth disease.

[Several yellow fever cases in an endemic area in Ivory Coast: serological and epidemiological evidence (author's transl)]. / Diagnostic de plusieurs cas de fièvre jaune en zone d'émergence endémique en Côte-d'Ivoire.

1 - More than hundred febrile haemorrhagic jaundice cases with an unexpectedly high number of death happened in the north-west of the Ivory Coast between October 1977 and December 1977. It was the end of the rainy season and in this area, yellow fever is a dreadful eventuality. 2 - Epidemiological and serological survey was immediately carried out. Presence of numerous yellow fever potential vectors was well known and has been noticed in September 1977; there were some left in December 1977. Therefore no virus was isolated either in September or further. 3 - Haemagglutination-inhibition, complement-fixation and neutralization tests were performed with six flavivirus antigens, i.e. yellow fever, Wesselsbron, West Nile, Ntaya, Uganda S and Zika. 2 or 3 sera from 29 patients and 49 school children who have recent jaundice history, sometimes with haemorrhagic symptoms, were available. Single sera from 52 young rural workers and 402 inhabitants of surrounding villages were examined too. 4 - By the way of clinical, epidemiological, serological evidence, authors concluded 21 cases were certainly yellow fever. Evidence of 2 other cases was demonstrated by specific micropathological features. Furthermore, by serological results, 20 were probably yellow fever, 15 were inconclusive and 476 certainly not. 5 - Authors discussed some specific difficulties of yellow fever retrospective diagnosis in flavivirus endemic area.