Analysis of Concentric and Eccentric Power in Flywheel Exercises Depending on the Subjects' Strength Level and Body Mass.

ABSTRACT: Asencio, P, García-Valverde, A, Albaladejo-García, C, Beato, M, Moreno-Hernández, FJ, and Sabido, R. Analysis of concentric and eccentric power in flywheel exercises depending on the subjects' strength level and body mass. J Strength Cond Res XX(X): 000-000, 2024-The objective of this study is to describe how flywheel exercise mechanical outputs are affected by the athletes' body mass (BM) and strength level and by the exercise type. Forty-six recreational athletes came to a laboratory 3 times. On the first day, descriptive data, squat (1 repetition maximum: 1RM) and flywheel familiarization were performed. After a second day of familiarization, subjects performed a randomized flywheel exercise-testing protocol of squat and split squat exercises. The variables used for data analysis were peak concentric power and peak eccentric power, eccentric/concentric ratio, and their relationship with 1RM/BM. Subjects were assigned to a stronger or weaker group according to their 1RM/BM ratio. Group differences were found in absolute values of eccentric overload (EOL) (p < 0.01; effect size [ES] = 0.51) and EOL/BM (p < 0.01; ES = 0.46) only in the split squat. Absolute power values in the concentric phase showed differences between inertial load (p < 0.01; ES = 0.41). The stronger group did not present significant differences between inertial loads during squat (p < 0.01; ES = 0.46), but they showed different ratios with light inertias in comparison with the weaker group (p < 0.01; ES = 0.46). There were significant differences between groups with light inertias in split squat (nondominant) and squat exercises (p < 0.05; ES = 0.29) in the eccentric and concentric phases (p < 0.116; ES = 0.20). Squat and split squat exercises present different profiles depending on the training level. In conclusion, it is recommended that practitioners perform a test to understand the inertial load-power profile (concentric, eccentric, and their ratio) for each exercise and also consider the user's strength level for selection of the inertial load and for the exercise to use in training.

Effects of variable intensity and constant intensity flywheel resistance training programs on specific soccer players' performance.

Resistance training programs play a crucial role in optimizing soccer performance. The aim of this study is to compare performance outcomes in sport-specific tasks after implementing two different flywheel resistance training (FRT) programs: variable intensity (VI) and constant intensity (CI). Seventeen (n = 17) amateur footballers were divided into VI and CI groups with the same training volume. For the VI group, a decrease in inertial load was implemented every four sessions, whereas the CI group maintained a constant load during the entire program. After different familiarization sessions and testing (sprint, change of direction, jump, one-repetition maximum and flywheel strength variables), ten sessions of FRT were performed over 5 weeks. Both groups showed similar improvements in the one-repetition maximum (p < 0.01) but the CI group had significant improvements in the 10-m sprint (p = 0.04; ES = 0.72), emphasizing the potential benefits of medium inertial loads to maximize power and specificity in sport tasks. However, no significant differences were observed in the countermovement jump, change of direction and 30-m sprint, possibly attributed to neuromuscular fatigue from a high-volume training schedule and friendly matches. The study highlights the importance of considering training load distribution in FRT programs. The findings emphasize the need for complementary training to maximize the jump and change of direction abilities and caution against high-volume training and friendly match scenarios. In conclusion, FRT programs, whether varying in intensity or not, can yield medium-term performance improvements for soccer players.

The Use of Incremental, Decremental or a Random Order of Loads does not Affect Peak velocity Values during Bench Press Throw Load-velocity Relationships.

The aim of this study was to assess the influence of the load order used (i. e. incremental, decremental or random loads order) during the bench press throw load-velocity profile on peak velocity achieved against four different loads (20-40-60-80% of one repetition maximum [1RM]). Both intraclass correlation coefficient (ICC) and coefficient of variation (CV) were calculated to assess the reliability of the measures. A repeated measures ANOVA was used to assess differences between protocols. A linear regression analysis was performed to assess the load-velocity relationships among the different protocols. Peak velocity showed good to high ICC values independently of the load used (ICC=0.83-0.92). CV scores showed good reliability (ranging between 2.2 and 6.2%). No significant differences in peak velocity attained at each load were found between the three testing protocols (p>0.05). In addition, peak velocity at each load was very large to almost perfect, correlated between protocols (r=0.790-0.920). The linear regression model showed a significant relationship between testing protocols (p<0.001; R2=0.94). In conclusion, due to some ICC scores below 0.9 and R2 below 0.95, the indistinct use of different load-order protocols to assess load-velocity relationships in the bench press throw exercise is not recommended.

Influence of the Strap Rewind Height During a Conical Pulley Exercise.

The use of flywheel devices has increased in popularity within resistance training programs. However, little is known about modifiable variables which may affect power output responses, as the rope length and the height level used in a conical pulley device. The aim of this study was to assess the influence of using three different rope lengths (1.5, 2.5 and 3.5 meters) and four different height levels (L1, L2, L3 and L4) on concentric peak power (PPconc), eccentric peak power (PPecc) and eccentric overload (eccentric/concentric PP ratio; EO) during conical pulley exercises (i.e. seated and stand-up row). A total of 29 recreationally trained subjects (25.3±7.1 years; 1.74±0.06 m; 72.5±8.3 kg) took part in the study. Testing sessions consisted of 1 set of 10 repetitions under each condition; experiment 1: seated row exercise using the three different rope lengths; experiment 2: stand-up row exercise using four different height levels of the conical pulley. Results from experiment 1 did not show differences between rope lengths, although a trend for greater PPecc (ES=0.36-0.38) and EO (ES=0.40-0.41) was found when using longer rope lengths (2.5 and 3.5). Experiment 2 showed significant increases in both PPconc and PPecc as the height level used was closer to the cone base (L4). In contrast, EO values were significantly greater when using upper height levels (L1). These results suggest that the height level used during conical pulley exercises highly influences power output responses. Therefore, this variable should be carefully managed depending on the training goal (e.g. power vs hypertrophy).