Ezzedine Bouhlel

Relationships of Peak Leg Power, 1 Maximal Repetition Half Back Squat, and Leg Muscle Volume to 5-m Sprint Performance of Junior Soccer Players

Chelly, MS, Chérif, N, Ben Amar, M, Hermassi, S, Fathloun, M, Bouhlel, E, Tabka, Z, and Shephard, RJ. Relationships of peak leg power, 1 maximal repetition half back squat, and leg muscle volume to 5-m sprint performance of junior soccer players. J Strength Cond Res 24(1): 266-271, 2010-Performance over very short distances (1-5 m) is important in soccer. We investigated this in 23 male regional-level soccer players aged 17.2 ± 0.7 years, filming body markers to determine the average velocity and acceleration over the first step (VS and AS) and the first 5 m (V5, A5). Data were related to scores on a force-velocity test, squat jump (SJ), countermovement jump (CMJ), and 1 maximal repetition (1 RM) half back squat. Leg and thigh muscle volumes were also assessed anthropometrically. V5 was positively correlated with leg and thigh muscle volumes (r = 0.61, p < 0.05; r = 0.43, p < 0.05, respectively), SJ power (absolute and relative to body mass, r = 0.45, p < 0.05; r = 0.43, p < 0.05, respectively), absolute force-velocity leg power (r = 0.49, p < 0.05), and 1 RM half back squat (r = 0.66, p < 0.001). The use of dimensional exponents did not change coefficients materially. VS was also correlated with leg muscle volume and 1 RM back half squat (r = 0.56, p < 0.01; r = 0.58, p < 0.01, respectively) and more weakly with force-velocity leg power and SJ force (r = 0.49, p < 0.05; r = 0.46, p < 0.5, respectively). However, the CMJ was unrelated to velocity or acceleration. Sprinting ability is correlated with measures of power and force such as the force-velocity test, SJ, and 1 RM half back squat; such measures thus offer useful guidance to soccer coaches who wish to improve the short-distance velocity of their players.

Ramadan fasting and the GH/IGF-1 axis of trained men during submaximal exercise.

Aims: The aim of this study was to explore possible changes in body composition, blood glucose regulation, plasma growth hormone (GH), insulin-like growth factor 1 (IGF-1), insulin-like growth factor-binding protein-3 (IGFBP-3), and insulin concentrations of trained athletes in response to the intermittent fasting and dehydration of Ramadan observance. Methods: Nine trained male rugby players (age 19 ± 2 years, height 1.78 ± 0.74 m) were tested 3 times: before Ramadan (C), at the end of the first week (R1), and during the fourth week (R2). They performed a progressive cycle ergometer test at each visit. The work rate was increased in 6-min stages corresponding to 20, 30, 40, 50 and 60% of &Wdot; max. Substrate oxidation was evaluated by indirect calorimetry. On each occasion, substrate and plasma hormone concentrations were measured at rest and at the end of the exercise. Results: Ramadan fasting induced a significant decrease in body mass and body fat (R2 vs. C, p < 0.001). Plasma concentrations of glucose, insulin, GH, IGF-1 and IGFBP-3 did not change significantly between C and R2, either at rest or following exercise. Conclusion: Ramadan fasting induces positive changes in body composition without disturbing glucose regulation or activity of the GH/IGF-1 system.

Crossover and maximal fat-oxidation points in sedentary healthy subjects: Methodological issues

AIM Our study aimed to assess the influence of protocol on the crossover point and maximal fat-oxidation (LIPOX(max)) values in sedentary, but otherwise healthy, young men. METHODS Maximal oxygen intake was assessed in 23 subjects, using a progressive maximal cycle ergometer test. Twelve sedentary males (aged 20.5±1.0 years) whose directly measured maximal aerobic power (MAP) values were lower than their theoretical maximal values (tMAP) were selected from this group. These individuals performed, in random sequence, three submaximal graded exercise tests, separated by three-day intervals; work rates were based on the tMAP in one test and on MAP in the remaining two. The third test was used to assess the reliability of data. Heart rate, respiratory parameters, blood lactate, the crossover point and LIPOX(max) values were measured during each of these tests. RESULTS The crossover point and LIPOX(max) values were significantly lower when the testing protocol was based on tMAP rather than on MAP (P<0.001). Respiratory exchange ratios were significantly lower with MAP than with tMAP at 30, 40, 50 and 60% of maximal aerobic power (P<0.01). At the crossover point, lactate and 5-min postexercise oxygen consumption (EPOC(5 min)) values were significantly higher using tMAP rather than MAP (P<0.001). During the first 5 min of recovery, EPOC(5 min) and blood lactate were significantly correlated (r=0.89; P<0.001). CONCLUSION Our data show that, to assess the crossover point and LIPOX(max) values for research purposes, the protocol must be based on the measured MAP rather than on a theoretical value. Such a determination should improve individualization of training for initially sedentary subjects.

Technical and tactical analysis of high level kickboxing matches

The purpose of the study was to analyze the technical and tactical aspects of high level Kickboxing matches. A total of 45 matches (135 rounds) from the World Championship 2009 and 2011 of male kickboxers were analyzed using notational analysis system to determine the technical and tactical aspects (i.e., offensive, defensive techniques and combined actions) considering combat rounds, weight divisions and match outcome. Kickboxers were engaged in offensive actions more than defensive ones (P<0.001). The most used techniques were straight punches, roundhouse kick, block/parry and foot defense (P<0.001), while punch combinations were the most used combination type. Winners used more offensive (i.e., hook punches), defensive techniques (i.e., foot defense and clinch) and punch combinations than losers. Significant interation effect of weight category, match outcome and rounds were found on offensive and defensive techniques. The activity in international kickboxing competitions was modulated by weight categories with a significant effect of combat stage. Winners applied more offensives and defensives techniques than defeated athletes. Our findings suggest that to win a match, athletes should be motivated by developing the most used offensives techniques and coaches should structure specific training to maintain a high rate of techniques ‘delivery during the combat.

Effect of Ramadan intermittent fasting on body composition and neuromuscular performance in young athletes: a pilot study

There is a conflict in the literature with regard to effects of the Ramadan intermittent fasting (RIF) on body composition and neuromuscular performance. The purpose of this pilot study was to examine the effect of the RIF on body mass/composition and neuromuscular performance during maximal voluntary contraction (MVC) and a muscle endurance exercise (Tlim ) of the knee extensors. Eight adolescents (17.2 ± 0.5 years) karate players were tested. Anthropometric variables (i.e. body mass, body mass index, fat mass and lean body mass) were evaluated 7 days before Ramadan (T1), and on days 7 (T2) and 28 (T3) of Ramadan. Each subject performed three MVC and a Tlim at 75% of MVC at T1, T2, and T3. Surface electromyographic (EMG) activity of vastus lateralis and vastus medialis was recorded during these neuromuscular tests. The anthropometric variables were unaltered by RIF. Likewise, there was no significant effect of RIF on the MVC (P = 0.29) and the Tlim (P = 0.22). This result was in accordance with the absence of change in both EMG activity level during MVC and in the rate of changes in EMG parameters (EMG activity level and frequency content) during Tli m . The results of the present study suggest that RIF does not impair maximal force generating capacity and muscle endurance at 75% of MVC. Therefore, Muslim experienced athletes could maintain their neuromuscular performance level by undertaking usual training loads during RIF.

EFFECT OF A PRIOR FORCE-VELOCITY TEST PERFORMED WITH LEGS ON SUBSEQUENT PEAK POWER OUTPUT MEASURED WITH ARMS OR VICE VERSA

Bouhlel, E, Chelly, MS, Gmada, N, Tabka, Z, and Shephard, R. Effect of a prior force-velocity test performed with legs on subsequent peak power output measured with arms or vice versa. J Strength Cond Res 24(x): 000-000, 2010-The aim of this study was to examine whether measurement of peak anaerobic power (Wpeak) by force-velocity test using the arms or the legs influenced the performance obtained when the opposite muscle group was tested. Ten trained male throwers (age: 20.6 ± 2; stature: 1.82 ± 0.06 m; and body mass: 85.5 ± 17.2 kg) performed, on separate days, 2 Monark cycle-ergometer protocols comprising (a) arm cranking (A1) followed by a leg cycling (L2) force-velocity test (series A-L) and (b) a leg cycling (L1) followed by an arm cranking (A2) force-velocity test (series L-A). On each day, 8 minutes of seated rest separated the 2 force-velocity tests. Arterialized capillary blood was collected from the finger tips for blood lactate analysis at rest and at the end of each force-velocity test. Wpeak-A1 and Wpeak-A2 were similar (8.1 ± 1.7 and 8.6 ± 1.5 W·kg−1, respectively). Wpeak-L1 and Wpeak-L2 were 14.0 ± 3 and 13.4 ± 2.8 W·kg−1 (NS). Blood [La] increased significantly after each force-velocity test (p < 0.001), but peak blood [La] did not differ significantly between L1 (6.6 ± 1.2) and L2 (6.2 ± 1.4 mmol·L−1) or between A1 (7.2 ± 1.0) and A2 (7.4 ± 1.6 mmol·L−1). In this population, force-velocity tests performed using the legs or the arms did not induce a significant decrease in force-velocity determinations of peak anaerobic power performed subsequently with the opposite muscle group. In strength-trained athletes, the force-velocity approach can thus be used to measure the peak power output of both the legs and the arms in a single laboratory session, without adversely affecting estimates of an athletes performance.

Contents Vol. 52, 2008

115 New Aspects in Quality and Biofunctionality of Foods First Symposium of the Vienna Research Platform of Nutrition and Food Sciences (VRPNFS) April 25, 2008, Vienna, Austria Guest Editors: Elmadfa, I.; Wagner, K.-H. (Vienna) (available online only) 174 The Official FENS Calendar 175 FENS News 176 IUNS News