Spiros Kellis

The effects of a twenty-four-week aquatic training program on muscular strength performance in healthy elderly women.

The purpose of the present study was to determine the effectiveness of a 24-week aquatic training (AT) program, which included both aerobic and resistance components, on muscle strength (isometric and dynamic), flexibility, and functional mobility in healthy women over 60 years of age. Twenty-two subjects were assigned randomly to either an AT (n = 12) or a control (C, n = 10) group. Volunteers participated in a supervised shallow-water exercise program for 60 minutes a day, 3 days a week; the exercise program consisted of a 10-minute warm-up and stretching, 25 minutes of endurance-type exercise (dancing) at 80% of heart rate (HR)max, 20 minutes of upper- and lower-body resistance exercises with specialized water-resistance equipment, and a 5-minute cool down. Maximal isometric torque of knee extensors (KEXT) and knee flexors (KFLEX) were evaluated by a Cybex Norm dynamometer, grip strength (HGR) was evaluated using a Jamar hydraulic dynamometer, and dynamic strength was evaluated via the 3 repetition maximum (3RM) test for chest press, knee extension, lat pull down, and leg press. Jumping performance was evaluated using the squat jump (SJ), functional mobility with the timed up-and-go (TUG) test, and trunk flexion with the sit-and-reach test. Body composition was measured using the bioelectrical impedance method. The AT induced significant improvements in KEXT (10.5%) and KFLEX (13.4%) peak torque, HGR strength (13%), 3RM (25.7–29.4%), SJ (24.6%), sit-and-reach (11.6%), and TUG (19.8%) performance. The AT group demonstrated a significant increase in lean body mass (3.4%). No significant changes in these variables were observed in the C group. The results indicate that AT, with both aerobic and resistance components, is an alternative training method for improving neuromuscular and functional fitness performance in healthy elderly women.

Effects of low- and high-volume resistance exercise on postprandial lipaemia

Postprandial lipaemia (PL) is associated with the metabolic syndrome, CVD and endothelial dysfunction. Aerobic exercise has been shown to reduce PL. Although resistance exercise is recommended for the improvement of the quality of life, management of body weight and prevention of several disorders, its effect on PL has received little attention. The present study examined the effects of low-volume resistance exercise (LVRE) and high-volume resistance exercise (HVRE) on PL. Ten healthy young men performed three trials, each conducted over 2 d. On the afternoon of day 1, they either refrained from exercise (control), performed LVRE (two sets of eight exercises, twelve repetitions at twelve repetitions maximum (RM) in each set; energy expenditure 0 x 76 MJ), or performed HVRE (four sets of eight exercises, twelve repetitions at 12 RM in each set; energy expenditure 1 x 40 MJ). On the morning of day 2 they consumed a meal containing 67 kJ/kg body weight, of which 65 % energy was from fat. Blood samples were obtained in the fasted state and for 6 h postprandially. The total area under the TAG curve (AUC; mmol/l x h) was lower (P<0 x 05) in HVRE (8 x 76 (sd 3 x 20)) and LVRE (9 x 29 (sd 3 x 64)) compared with control (11 x 60 (sd 4 x 35)). The incremental AUC was lower in HVRE compared with control (3 x 07 (sd 2 x 53) v. 5 x 58 (sd 3 x 72)), but not different between LVRE (3 x 86 (sd 2 x 29)) and control. In conclusion, resistance exercise of 1 x 40 MJ (four sets - eight exercises - twelve RM) or 0 x 76 MJ (two sets - eight exercises - twelve RM) before a high-fat meal reduces the total postprandial lipaemic response.

Effects of agonist and antagonist muscle fatigue on muscle coactivation around the knee in pubertal boys.

In many activities the knee joint flexes and extends actively with the involvement of both knee extensor and flexor muscle groups. Consequently the examination of the muscle activity during reciprocal movements may provide useful information on the function of these two muscle groups during fatigued conditions. Therefore, the purpose of this study was to examine the activity of antagonist muscles during a reciprocal isokinetic fatigue test of the knee extensors and flexors. Fifteen healthy pubertal males (age 13.8+/-0.8 years) performed 22 maximal isokinetic concentric efforts of the knee extensors at 60 degrees s(-1). The EMG activity of vastus medialis (VM), vastus lateralis (VL) and biceps femoris (BF) was recorded using surface electrodes. The motion ranged from 100 to 0 degrees of knee flexion. The average moment and average EMG (AEMG) at 10-30 degrees, 31-50 degrees, 51-70 degrees and 71-90 degrees angular position intervals were calculated for each repetition. Twenty efforts were further analyzed. Two-way repeated measures analysis of variance (ANOVA) tests indicated a significant decline of moment during the test (p<0.025). The VM and VL AEMG at longer muscle lengths increased significantly as the test progressed whereas the AEMG at short muscle lengths (10-30 degrees ) did not significantly change. The agonist AEMG of BF during the first repetition demonstrated a significant increase after the ninth repetition (p<0.025). The antagonist AEMG of all muscles did not change significantly during the test. These results indicate that there is consistent antagonist activity during both extension and flexion phases of an isokinetic reciprocal fatigue test. It can be concluded that during an isokinetic reciprocal fatigue test, both knee extensors and flexors are fatigued. However, this condition does not have a significant effect on the EMG patterns of these muscles when acting as antagonists during the test.

Muscle metabolism and performance improvement after two training programmes of sprint running differing in rest interval duration

Abstract Repeated-sprint training often involves short sprints separated by inadequate recovery intervals. The effects of interval duration on metabolic and performance parameters are unclear. We compared the effects of two training programmes, differing in rest interval duration, on muscle (vastus lateralis) metabolism and sprint performance. Sixteen men trained three times a week for 8 weeks, each training session comprising 2–3 sets of two 80-m sprints. Sprints were separated by 10 s (n = 8) or 1 min (n = 8). Both training programmes improved performance in the 100-, 200-, and 300-m sprints, but the improvement was greater in the 10-s group during the final 100 m of the 200- and 300-m runs. Independent of interval duration, training mitigated the drop of muscle ATP after two 80-m sprints. The drop in phosphocreatine and the increases in glucose-6-phosphate and fructose-6-phosphate after two 80-m sprints were greater in the 10-s group. In conclusion, training with a limited number of repeated short sprints (≤10 s) may be more effective in improving speed maintenance in 200- and 300-m runs when performed with a 1:1 rather than a 1:6 exercise-to-rest ratio. This may be due to a greater activation of glycolysis caused, in part, by the limited resynthesis of phosphocreatine during the very short rest interval.

Biochemical evaluation of running workouts used in training for the 400-m sprint.

Saraslanidis, PJ, Manetzis, CG, Tsalis, GA, Zafeiridis, AS, Mougios, VG, and Kellis, SE. Biochemical evaluation of running workouts used in training for the 400-m sprint. J Strength Cond Res 23(8): 2266-2271, 2009-A 400-m runner relies primarily on the lactate system for energy production. Although several running distances and schemes are used in training for this event, it is not clear which one(s) causes maximal activation of the lactate system so as to optimize adaptations of the lactic capacity. This study examined the effect of 4 running workouts differing in distance (300 vs. 400 m) and mode of execution (continuous/single vs. intermittent) on stimulation of the lactate system and biochemical markers of metabolism and muscle damage. Twelve young men performed 4 runs at maximal effort: 300, 3 × 100, 400, and 2 × 200 m. Blood was drawn before and after exercise for the measurement of lactate, glucose, creatinine, and creatine kinase (CK). Average speed was higher (p < 0.001) in the 300- vs. 400-m tests (7.52 ± 0.50 vs. 7.08 ± 0.59 m·s−1) and in the intermittent vs. continuous tests (7.45 ± 0.50 vs. 7.15 ± 0.58 m·s−1). Lactate was higher in the intermittent vs. continuous tests (16.3 ± 2.2 vs. 15.0 ± 2.0 mmol·L−1, p < 0.05). Serum glucose, creatinine, and CK increased after exercise (p ≤ 0.001), and glucose was higher in the 400- vs. 300-m trials (5.76 ± 0.46 vs. 5.33 ± 0.30 mmol·L−1, p = 0.032). In conclusion, although all 4 running regimens greatly stimulated the lactate system, it appears that the intermittent workouts are superior compared with continuous ones of the same total distance in increasing the ability for energy production via the lactate system. Thus, intermittent workouts can be successfully used by 400-m athletes to develop specific (speed) endurance and should be considered to precede the continuous runs of racing distance within a macrocycle.

Analysis and comparison of fast break in top level handball matches

The aim of this study was to describe an alternative approach in order to estimate the level of specific endurance (stamina) via video-analysis in handball athletes, which is required during the whole game. One thousand five hundred three (1503) attacks from 15 matches of 8 teams participating in the first division of the 2003 National Men’s Handball Championship were studied. For the analysis, all attacks were recorded and categorized based on the type of fast break. Furthermore, for each type of attack the outcome of the shot (goal, riposte, missed goal) and the offensive errors were recorded. All the fast break attempts (successful ones or not) were taken into consideration. The data analysis was conducted using Crosstabulation and chi-square tests. The results revealed that, during the first half, the 1st and 2nd wave were used in a percentage of 45,9% and 54,1%, respectively (p<0.05), although during the second half the percentage of each type was 63,3% and 36,7%, respectively (p<0.05). The third wave of fast break was not recorded. The number of successful attempts of fast break in the first half (77,1%) was greater than in the 2nd half (66,9%) (p<0.05). During the first half the frequency of the 1st wave (45,9%) was lower than that in the 2nd wave (54,1%) (p<0.05). However, during the second half the 1st wave’s frequency (63,3%) was greater compared to the 2nd wave’s (36,7%) (p<0.05). The form of analysis which was used to record, research and compare the frequency of appearance of fast break showed a reduction of fast break in the second half compared to the first half. There was also a significant difference between the two half times regarding the successful and unsuccessful fast breaks. The results may indicate some influence of training specificity and provide suggestions to coaches regarding the organisation of handball training drills that will possibly lead to an increase in explosive power.

Knee Muscles Isokinetic Evaluation after a Six-Month Regular Combined Swim and Dry-Land Strength Training Period in Adolescent Competitive Swimmers

Abstract Previous studies demonstrated significant increases in the shoulder internal rotators’ peak torque values and unilateral muscular imbalances of the shoulder rotators after a competitive swim period. However, there are no similar data concerning the knee muscles. The purpose of the current study was to examine the effects of a six-month training period on knee flexor and extensor peak torque values, examine a possible bilateral strength deficit and evaluate the unilateral strength balance in competitive swimmers. Eleven male adolescent swimmers (age: 14.82 ± 0.45 years) were tested for concentric knee extension and flexion peak torque (60°/s) with an isokinetic dynamometer, before and after a regular combined swim and dry-land strength training period. A trend towards greater improvements in the knee extensor compared to flexor muscles peak torque was observed. Furthermore, the bilateral strength deficit remained almost unchanged, whereas unilateral strength imbalance was increased for both limbs. However, all results were nonsignificant (p > 0.05). According to the data presented, a six-month regular combined swim and dry-land strength training period caused non-significant alterations for all the parameters evaluated during isokinetic testing. This study highlights the fact that competitive adolescent swimmers demonstrated unilateral knee strength imbalances throughout a long period of their yearly training macrocycle.

Reliability of concentric and eccentric strength of hip abductor and adductor muscles in young soccer players

The concentric and eccentric strength profile and muscular balance of the hip joint are important parameters for success in soccer. This study evaluated the reliability for the assessment of hip abduction and adduction isokinetic strength over a range of angular velocities (30 and 90°/s) and types of muscular actions (concentric and eccentric) in young soccer players. The reliability for the assessment of reciprocal (conventional and functional) and bilateral torque ratios was also examined. Fifteen male soccer players (15±1 years) performed two sessions, separated by three days. The testing protocol consisted of five maximal concentric and eccentric hip abductions and adductions of both legs at angular velocities of 30°/s and 90°/s. The peak torque was evaluated in young soccer players using an isokinetic dynamometer (Cybex Norm), and the reciprocal strength ratios (conventional and functional) and bilateral ratios (non-preferred to preferred leg ratios) were calculated. The test-retest reliability for the assessment of peak torque (ICC = 0.71-0.92) and of reciprocal muscle group ratios (ICC = 0.44-0.87) was found to be moderate to high. Bilateral torque ratios exhibited low to moderate reliability (ICC = 0.11-0.64). In conclusion, isokinetic strength of hip abductor and adductor muscles and the conventional and functional strength ratios can be reliably assessed in young soccer players, especially at low angular velocities. The assessment, however, of bilateral strength ratios for hip abductor/adductor muscles should be interpreted with more caution.

Effects of a Modified Ballet Class on Strength and Jumping Ability in College Ballet Dancers

The ability to jump high with precision is an important component of the ballet dancers technique. The aim of this study was to evaluate the effect of a modified ballet class on strength and jumping ability in high level female dancers. Seventeen female ballet students were divided into two groups, experimental and control, and tested before and after an 8-week, 2 times/week intervention for peak torque of knee extensors and flexors at 60°and 180°, and jumping ability (squat jump, countermovement jump, countermovement with arm swing jump, sauté in first position, and sauté in first position with port de bras). Statistical analysis was performed using Analysis of Variance (Anova 2x2) with repeated measure of factor time (pre and post). T-test with Bonferroni adjustment was used to assess any differences between groups. The experimental group showed improvement in height (7.7%), takeoff velocity (4.0%), and power (5.1%) of the squat jump. In addition, increases were revealed in peak (60°, 11.9%; 180°, 7.8%) and relative peak torque (60°, 13.2%; 180°, 9.2%) of the right knee flexors. Moreover, enhancements of the knee flexor-extensor strength ratio in both angular velocities were found (60°, 10.4%; 180°, 9.7%). These outcomes suggest that the proposed program could help ballet dancers improve the height of their vertical jumps and leg strength.