For many sporting activities, initial speed rather than maximal speed would be considered of greater importance to successful performance. The purpose of this study was to identify the relationship ...between strength and power and measures of first-step quickness (5-m time), acceleration (10-m time), and maximal speed (30-m time). The maximal strength (3 repetition maximum 3RM), power (30-kg jump squat, countermovement, and drop jumps), isokinetic strength measures (hamstring and quadriceps peak torques and ratios at 60 degrees .s(-1) and 300 degrees .s(-1)) and 5-m, 10-m, and 30-m sprint times of 26 part-time and full-time professional rugby league players (age 23.2 +/- 3.3 years) were measured. To examine the importance of the strength and power measures on sprint performance, a correlational approach and a comparison between means of the fastest and slowest players was used. The correlations between the 3RM, drop jump, isokinetic strength measures, and the 3 measures of sport speed were nonsignificant. Correlations between the jump squat (height and relative power output) and countermovement jump height and the 3 speed measures were significant (r = -0.43 to -0.66, p < 0.05). The squat and countermovement jump heights as well as squat jump relative power output were the only variables found to be significantly greater in the fast players. It was suggested that improving the power to weight ratio as well as plyometric training involving countermovement and loaded jump-squat training may be more effective for enhancing sport speed in elite players.
Introduction: Flywheel training devices have initially been used as means of astronaut conditioning in outer space during long missions. The system uses a rotating disc to store the energy during the ...concentric phase of the movement and converts it to resistance during the eccentric phase. The inertia of the flywheel offers the load of the exercise performed. Later, these devices started being used in injury rehabilitation and performance training. Objective: The objective of the study was to measure the effect of isoinertial exercises using a flywheel training device on lower limb power and stability. Also, we wanted to verify if a positive correlation can be found between force, power and stability. Methods: 15 female volleyball players were included in the study N=15. During 4 months the subjects trained twice a week using the flywheel device. Initial and final tests were performed using OptoJump, Y balance test and the device’s own measuring system. The measured parameters were average power, average force, jump height and composite reach distance index. Results: Significant improvement have been found between the initial and final results for power, force, jump height and composite reach distance index p<.01. Conclusions A flywheel isoinertial training device can be seen as a viable alternative for power and stability development for volleyball players.
We consider the Korteweg–de Vries (KdV) equation, by employing the recursion operator of the KdV equation, some new operator identities for the higher order linearized Hamiltonians around one soliton ...are verified, it follows that the linearized operators can be diagonalized to their constant coefficient counterparts. The linearized operators around the KdV multi-solitons are isoinertial and the discrete eigenvalues of which are determined. As a direct consequence, we give a new proof of the stability of the KdV multi-solitons and extend the approaches of Maddocks and Sachs (1993) and Neves and Lopes (2006). Finally, some discussions of the KdV H−1 conservation law are presented by evaluating the inverse recursion operator of the KdV equation.
The aim of this study was to evaluate the effects of varying flywheel inertia on velocity and power during flywheel squats. Fifteen healthy physically active males performed 6 maximal effort flywheel ...half-squats at each of 0.029, 0.061, 0.089 and 0.121 kg·m
2
, with velocity recorded via 3D motion capture and power recorded via inbuilt transducer. Peak concentric velocity (χ2 = 37.9; p < 0.001), peak eccentric velocity (χ2 = 24.9; p < 0.001), mean concentric velocity (F(3) = 52.7; p < 0.001) and mean eccentric velocity (χ2 = 16.8; p < 0.001) all tended to decrease with increases in flywheel inertia, whereas the ratio of peak eccentric to peak concentric power (F(3) = 4.26; p = 0.010) tended to increase. Flywheel inertia had no significant effect on peak concentric or eccentric power, or the ratio of eccentric to concentric peak or mean velocities. The best fit subject-specific inertia-velocity relationships were reported for peak concentric velocity (median linear R
2
= 0.95, median logarithmic R
2
= 0.97). The results suggest that velocity, rather than power, should be used to prescribe and monitor flywheel squat exercise intensities, and that individualized linear relationships between inertia and peak concentric velocity can be used for this purpose.
ABSTRACTExercise load is a key component in determining end-point adaptations to resistance exercise. Yet, there is no information regarding the use of different inertia (i.e. loads) during ...iso-inertial flywheel resistance exercise, a very popular high-intensity training model. Thus, this study examined power, work, force and eccentric-overload produced during flywheel resistance exercise with different inertial settings in men and women. Twenty-two women (n=11) and men (n=11) performed unilateral (in both legs) isolated concentric (CON) and coupled CON and eccentric (ECC) exercise in a flywheel knee extension device employing six inertias (0.0125, 0.025, 0.0375, 0.05, 0.075, 0.1 kg*m). Power decreased as higher inertias were used, with men showing greater (P< 0.05) decrements than women (-36% vs. -29% from lowest to highest inertia). In contrast, work increased as higher inertias were employed, independent of sex (P<0.05; ∼48% from lowest to highest inertia). Women increased CON and ECC mean force (46-55%, respectively) more (P<0.05) than men (34-50%, respectively) from the lowest to the highest inertia evaluated, although the opposite was found for peak force data (i.e. peak force increased more in men than in women as inertia was increased). Men, but not women, increased ECC overload from inertia 0.0125 to 0.0375 kg*m. While estimated stretch-shorting cycle use during flywheel exercise was higher (P<0.05) in men (6.6%) than women (4.9%), values were greater for both sexes when using low to -medium inertias. The information gained in this study could help athletes and sport and health professionals to better understand the impact of different inertial settings on skeletal muscle responses to flywheel resistance exercise.
This study aimed to evaluate the effect of flywheel training on female populations, report practical recommendations for practitioners based on the currently available evidence, underline the ...limitations of current literature, and establish future research directions. Studies were searched through the electronic databases (PubMed, SPORTDiscus, and Web of Science) following the preferred reporting items for systematic reviews and meta-analysis statement guidelines. The methodological quality of the seven studies included in this review ranged from 10 to 19 points (good to excellent), with an average score of 14-points (good). These studies were carried out between 2004 and 2019 and comprised a total of 100 female participants. The training duration ranged from 5 weeks to 24 weeks, with volume ranging from 1 to 4 sets and 7 to 12 repetitions, and frequency ranged from 1 to 3 times a week. The contemporary literature suggests that flywheel training is a safe and time-effective strategy to enhance physical outcomes with young and elderly females. With this information, practitioners may be inclined to prescribe flywheel training as an effective countermeasure for injuries or falls and as potent stimulus for physical enhancement.
The aims of the current systematic review were to evaluate the current literature surrounding the chronic effect of flywheel training on the physical capacities of soccer players, and to identify ...areas for future research to establish guidelines for its use.
Studies were identified following a search of electronic databases (PubMed and SPORTDiscus) in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA).
Eleven studies met the inclusion criteria and were included. The methodological quality of the included studies ranged between 10 and 18 with an average score of 15 points using the PEDro scale. The training duration ranged from 6 weeks to 27 weeks, with volume ranging from 1 to 6 sets and 6 to 10 repetitions, and frequency from 1 to 2 times a week. This systematic review reported that a diverse range of flywheel training interventions can effectively improve strength, power, jump, and changes of direction in male soccer players of varying levels.
Flywheel training interventions improve the physical capacities of soccer players of varying levels. Nonetheless, the current literature suggests contrasting evidence regarding flywheel training induced changes in sprint speed and acceleration capacity of soccer players.
Purpose:
To propose the concentric linear velocity measurement as a valid method to quantify load and individualise the prescription of flywheel training, we investigated the relationship between ...inertial load and mean concentric linear velocity (MCLV) during the flywheel squat exercise in a wide spectrum of intensities. In addition, we compared MCLV and subjective rating of perceived exertion (RPE) after each load.
Methods:
Twenty-five physically active men volunteered for this study (26.5 ± 2.9 years, 179.5 ± 4.2 cm, 81.6 ± 8.6 kg). After familiarization, all participants performed two inertial progressive load tests on separated days to determine the flywheel load-velocity profile and its reliability. Each participant performed 5 set of 6 repetitions of the flywheel squat exercise with different inertial loads (0.047, 0.104, 0.161, 0.245, 0.321 kg m
2
) selected in a counterbalanced and randomized order for each testing day. Average MCLV and RPE for each load were compared.
Results:
The inter-session intraclass correlation coefficient (ICC) showed values above 0.9 in all the included outcomes (MCLV: ICC = 0.91; RPE: ICC = 0.93). A significant correlation (
p
< 0.01,
R
2
= 0.80) between inertial load and MCLV was found. Similarly, significant correlation models (
p
< 0.01) were observed between RPE and load (
R
2
= 0.87) and (
R
2
= 0.71) between RPE and MCLV.
Conclusion:
The control of MCLV during flywheel exercise can be proposed as a valid method to quantify load and to individualize the prescription of flywheel training. In addition, RPE responses have demonstrated significant correlations with load and velocity. Therefore, RPE has been proposed as a valid and reliable alternative to control flywheel training.
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