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 dancer's 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.

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

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 non-significant (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.

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

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.

Prediction of peak oxygen uptake from a maximal treadmill test in 12- to 18-year-old active male adolescents.

The aims were to develop and validate a VO(2peak) prediction equation from a treadmill running test in active male adolescents. Eighty-eight athletes (12-18 yrs.) performed a maximal exercise test on a treadmill to assess the actual VO2peak and a 20m Shuttle-Run-Test (20mST). A step-wise linear regression analysis was used and the following equation for estimation of VO(2peak) (mL·kg⁻¹·min⁻¹) = 35.477 + 1.832 × duration in min - 0.010 × duration × body mass in kg was developed. The cross-validation statistics were: R = .54, CE = 0.1 mL·kg⁻¹min⁻¹, SEE = 2.5 mL·kg⁻¹·min⁻¹ (4.6%), and TE = 2.6 mL·kg⁻¹·min⁻¹ (4.9%). The cross-validation values (CE, SEE, and TE) were lower compared with those of previously published equations in adolescents that estimated VO(2peak) using anthropometric data, performance in 20mST, and energy cost at submaximal speeds.

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

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 x 100, 400, and 2 x 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

The contribution of stretch-shortening cycle and arm-swing to vertical jumping performance in children, adolescents, and adult basketball players.

This study examined from childhood to adulthood: (1) the effects of countermovement (use of stretch-shortening cycle-SSC) and arm-swing (AS) on vertical jumping (VJ) performance and (2) the ability to use the SSC and AS during VJ. Male basketball players (n = 106) were divided according to their age into: children (12.0 +/- 0.23), young adolescents (14.5 +/- 0.41), old adolescents (16.9 +/- 0.27), and adults (21.9 +/- 0.32). Each participant executed three maximal squat jumps (SJ), countermovement jumps without arms (CMJ) and with arms (CMJA). The contribution of SSC and AS was calculated by the augmentation (difference and percent change) in performance between CMJ and SJ, and CMJA and CMJ, respectively. CMJA performance was significantly (p < .05) higher than CMJ and SJ, and CMJ was higher than SJ within all age-groups. There were no significant differences (p > .05) among children, young and old adolescents, and adults in the percent contribution of SSC and AS to VJ performance. The variability in the contribution of SSC and AS to VJ performance was about twofold higher in children vs. adults. It appears that the ability to use the SSC and AS is not affected by the maturation process in males, trained in basketball.

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.

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.

The effects of a calisthenics and a light strength training program on lower limb muscle strength and body composition in mature women.

This study evaluated and compared the effectiveness of an aerobics-calisthenics (A-CAL) and an aerobics/weight training (A-WT) programs on lower limb strength and body fat (%). Thirty-five adult women (age 42.1 +/- 5.2 years) were randomly assigned to A-CAL (n = 14), A-WT (n = 14), or a control group (n = 7). The A-CAL and A-WT trained 3 days per week for 10 weeks. Maximal bilateral isometric and isokinetic knee extension (KEXT) and flexion (KFLEX) torque, squat jump (SJ), and body fat (%) were measured before and immediately after training. The results revealed nonsignificant differences between A-CAL and A-WT (p > 0.05). Both A-CAL and A-WT improved SJ (p < 0.001). A-WT increased isometric torque of KEXT and KFLEX (p < 0.05), isokinetic torque of KFLEX (p < 0.05), and decreased body fat (%) (p < 0.05) when compared with controls. In summary, the application of a 10-week light-weight training program improved selected strength parameters of healthy women, compared with controls, but the effectiveness of the calisthenics exercises as an independent form of strength training is dubious.