Vedran Hadžić

Quadriceps and hamstrings strength in team sports: Basketball, football and volleyball

Isokinetic strength evaluation of the quadriceps (Q) and hamstrings (H), in both concentric (con) and eccentric (ecc) mode of contraction, is an important part of the comprehensive evaluation and rehabilitation of athletes. Systematic preseason isokinetic evaluation of the knee is very useful in highlighting the athletes at risk for those injuries as well as for the optimization of the training process. The main purpose of this short review was to present the major findings of studies relating to this issue.

The role of radiation therapy in locally advanced breast cancer.

Abstract:  The purpose of the study was to evaluate and compare the impact of postoperative radiotherapy, whether it was based on the clinical stage at presentation of the disease or on the pathological downstaged disease after initial chemotherapy for non‐inflammatory locally advanced breast cancer (LABC). We retrospectively analyzed locoregional recurrence (LRR), relapse free survival (RFS), overall survival (OS) and disease free survival (DFS) in 55 patients treated for non‐inflammatory LABC with neoadjuvant chemotherapy and surgery with or without radiotherapy. The mean follow‐up was 55 months. The 3‐year OS was 74%, DFS 73% and RFS 87%. The OS and DFS benefit was seen in those receiving radiation, with a mean OS of 89 months versus 68 months (p = 0.029) and mean DFS of 72 months versus 54 months (p = 0.029). Total LRR was 11% (8% versus 17% in the non‐radiotherapy group, p = 0.349) and mean RFS of 95 months versus 86 months (p = 0.164). If the treatment planning was to be based on the original extent of the disease, then all patients in our study should have received adjuvant radiotherapy. Significantly lower OS and DFS without the addition of radiotherapy suggests that indication for radiation treatment should be based on the clinical pre‐chemotherapy stage rather than the pathological post‐chemotherapy stage. Radiation should therefore always be considered regardless of the response to initial chemotherapy for non‐inflammatory LABC.

Vertical jump performance of professional male and female volleyball players: effects of playing position and competition level.

Abstract Sattler, T, Hadžić, V, Dervišević, E, and Markovic, G. Vertical jump performance of professional male and female volleyball players: effects of playing position and competition level. J Strength Cond Res 29(6): 1486–1493, 2015—Vertical jump (VJ) performance is an important element for successful volleyball practice. The aims of the study were (a) to explore the overall VJ performance of elite volleyball players of both sexes, (b) to explore the differences in VJ performance among different competition levels and different playing positions, and (c) to evaluate the sex-related differences in the role of the arm swing and 3-step approach with arm swing on the jump height. We assessed the VJ capacity in 253 volleyball players (113 males and 140 females) from Slovenian first and second Volleyball Division. The height of squat jump (SJ), countermovement jump, block jump, and attack jump was tested using an Optojump system. We observed significant differences (p ⩽ 0.05) in VJ height between different levels of play that were most pronounced in the SJ. Position-related differences in VJ performance were observed in male players between receivers and setters (p ⩽ 0.05), whereas in females, VJ performance across different playing positions seems equal. Finally, we found that male players significantly better use the arm swing during VJ than females (p ⩽ 0.05), whereas the use of eccentric part of the jump and approach before the spike to improve VJ performance seem to be equally mastered activity in both sexes. These results could assist coaches in the development of jumping performance in volleyball players. Furthermore, presented normative data for jump heights of elite male and female volleyball players could be useful in selection and profiling of young volleyball players.

Can infrared thermography be used to monitor fatigue during exercise? A case study

Background Infrared thermographic imaging (IRTG) is a safe and reliable technology used to monitor skin temperature. The main aim of our study was to evaluate the relationship between skin temperature changes and muscle fatigue in order to answer the main research question if IRTG can be used to monitor muscle fatigue. Methods This was a case study performed on a 23-year-old trained middle distance runner. After warm-up the subject was exercising on the dynamometer for 7.5 min at 120°/s performing only concentric contractions of quadriceps. At the same time IRTG recording of both (exercising and non-exercising) quadriceps was performed. Results A correlational analysis that was performed in order to quantify the relationship between power and temperature change over time has shown that there is a significant negative correlation between skin temperature increase and power decrease (r = −0.543, p = 0.036) of exercising quadriceps. In linear regression model the exercising quadriceps power could be predicted from skin temperature. No such relationships were noted for the non-exercising limb that served as a control. Conclusion We believe that correlation between skin temperature change and muscle power output as described in this case study deserves further analysis on the larger sample including subjects of the different ages, health status, and physical abilities in order to create a new tool for monitoring the muscle fatigue.

Risk Factors for Eating Disorders Among Male Adolescent Athletes / Dejavniki Tveganja Motenj Hranjenja Med Športniki V Adolescenci

Abstract Objective. Eating disorders (ED) are an important and increasing problem in adolescents. The objective of this study was to examine the risk factors and the prevalence of risk for ED among male adolescent elite athletes and nonathletic controls. Differences between male athletes competing in aerobic, anaerobic and aerobic-anaerobic sports were examined as well. Methods. This was a cross-sectional epidemiological study. A cross-sectional questionnaire survey and anthropometric measurements were conducted on 351 adolescents (athletes n = 228; controls n = 123). All participants were aged 15-17 at the time of measuring. Risk for ED was determined using a SCOFF questionnaire. Results. The overall prevalence of the risk for ED in male adolescents was 24.8%, with no significant differences among athletes and controls or different subgroups of athletes (p>0.05), although the highest prevalence (37.2%) was registered in aerobic subgroup of athletes. Higher number of attempts to lose weight was associated with increased risk of ED in each group (athletes and controls). Other predictors referred to lack of breakfast and body composition in aerobic subgroup of athletes and number of meals and training frequency in anaerobic subgroup. The most common reasons for dieting were improvement of sport results (19.6-44.2%) and better self-esteem (41.5%) in athletes and controls respectively. Conclusions. Participation in the competitive sport itself is not associated with the increased risk for ED. It seems that risk factors for ED for adolescent athletes competing in aerobic and anaerobic sports represent a subject that deserves consideration and further investigation in the future IZVLEČEK Namen. Namen raziskave je bil ugotoviti dejavnike tveganja in prevalenco tveganja za motnje hranjenja med športniki adolescenti in kontrolno skupino ter razlike med športniki, ki tekmujejo v aerobnih, anaerobnih in v aerobno-anaerobnih športnih. Metode. Športniki so bili iz 22 različnih športnih panog (N = 228; kontrola N = 123). Merjenci so bili med meritvami stari od 15 do 17 let. Splošen vprašalnik se je nanašal na pogostost in trajanje treninga, zmanjševanje telesne teže, metode, ki so jih za to uporabljali, in prehranjevalne navade. Za oceno tveganja za nastanek motnje hranjenja je bil uporabljen vprašalnik SCOFF. Rezultati. Telesna sestava je bila izmerjena z napravo InBody230. Najvišja prevalenca tveganja za motnje hranjenja je bila opažena v aerobni skupini (37,2 %). Najpogostejši vzrok za zmanjševanje telesne teže je bil med športniki izboljšanje tekmovalnega dosežka (19,6 %-44,2 %), v kontrolni skupini pa dvig samopodobe (41,5 %). Dejavniki tveganja za razvoj motenj hranjenja se med skupinami razlikujejo. Najpogostejši je bil število poizkusov zmanjšanja telesne teže. V aerobni skupini se je kot najpomembnejši dejavnik pokazal zajtrk (p = 0,028). Zaključek. Dejavniki za povečano tveganje motenj hranjenja se v aerobni in aerobno-anaerobni skupini nanašajo na prehranjevalne navade, v anaerobni skupini pa na pogostost treninga. Trenerji so še vedno glavni razlog zmanjševanja telesne teže med športniki adolescenti

Relation of Lean Body Mass and Muscle Performance to Serum Creatinine Concentration in Hemodialysis Patients

Introduction Serum creatinine concentration is an important uremic marker and predictor of survival in dialysis patients. This cross-sectional case-control study was made to quantitatively describe the relation between lean body mass (LBM), physical performance measures, and serum creatinine values. Methods Ninety hemodialysis patients and 106 controls were measured by bioimpedance spectroscopy, handgrip strength, sit-to-stand test, and biochemical serum tests. Univariate and multivariate general linear models were used to analyze quantitative relations. Results At univariate regression LBM accounted for 13.6% variability of serum creatinine concentration. In adjusted analyses with age, height, and body mass, LBM persisted as the only significant predictor of midweek predialysis serum creatinine concentration. Physical performance measures handgrip strength and sit-to-stand performance did not improve prediction of serum creatinine. With addition of serum urea concentration and residual diuresis the predictive value of the regression model improved to account for 45% of serum creatinine variability. Each kg of LBM was associated with 7.7 μmol/l increase in creatinine concentration (95% CI 3.4-12.1, p=0.001). Conclusion Bioimpedance derived LBM has a significant linear relation with predialysis serum creatinine concentrations. Hereby described quantitative relation should help clinicians to better evaluate observed creatinine concentrations of hemodialysis patients when bioimpedance derived LBM is available.

Recommendations for physical activity for pregnant women

Properly selected and prescribed physical activity during pregnancy has a favorable effects on the health of pregnant women and the fetus, and is excellent preparation for childbirth. Absolute and relative contraindications to exercise during pregnancy are well defined, as well as the warning signs to terminate exercise while pregnant. Knowledge of these is essential for physically active pregnant women and exercise professionals that work with pregnant women. Pregnant women should be moderately physically active every day of the week for at least 30 minutes. The term moderate is thoroughly and clearly defined in the guidelines. Resistance exercises during pregnancy are safe but it is advised to use light loads and a large number of repetitions (e.g. 15-20 repetitions). Strength exercises for the pelvic floor muscles deserves a special place during pregnancy. Appropriate forms of physical activity for pregnant women are walking and jogging, swimming and aquatic exercise, cycling, Pilates and yoga, aerobics, fitness and cross-country skiing. Certain forms of physical activity need special adjustments (alpine skiing, ice skating and rollerblading, racket sports, team ball games, horseback riding and scuba diving).