Individualized Training Based on Force-Velocity Profiling During Jumping in Ballet Dancers

Effects of force- and velocity-oriented conditioning activities on jump height in strength-deficient male participants

Introduction

Various factors are known to influence the effectiveness of post-activation performance enhancement (PAPE) protocols. However, whether individual's force-velocity (FV) profile affects the impact of conditioning activity (CA) remains unclear. This study examined whether PAPE is influenced by addressing individual strength deficits, identified through FV profiling, using either force- or velocity-oriented conditioning. Specifically, we (i) assessed the effectiveness of force-oriented (PAPE-F) and velocity-oriented (PAPE-V) protocols on acute jump height (JH) performance in individuals with strength deficits and (ii) investigated whether the magnitude of force-velocity imbalance (FVimb) is significantly associated with PAPE in JH.

Methods

Twenty-five young (19-27 years), resistance-trained male individuals (≥2 years of continuous training) who exhibited a strength deficit, determined by FVimb in the squat jump (SJ), were included in this study. They performed either three sets of five assisted jumps (PAPE-V; load reduced by 30% of body mass) or three four-second sets of maximal isometric contractions (PAPE-F), each with 1 min rest intervals. JH was measured at baseline and 3, 6, and 9 min post-CA.

Results

A three-way (group × condition × time) repeated measures ANOVA revealed significant effects of time (F = 7.78; partial-η2 = 0.14; p < 0.01) and a significant condition × time interaction (F = 16.57; partial-η2 = 0.26; p < 0.01) for JH. The Bonferroni post hoc test revealed significant within-group improvements after PAPE-F at the 6th min (p < 0.01; ES = 0.32) and 9th min (p < 0.01; ES = 0.33) compared to baseline and after PAPE-V at the 3rd min (p < 0.01; ES = 0.24), 6th min (p < 0.01; ES = 0.36), and 9th min (p < 0.01; ES = 0.30) compared to baseline. Linear regression models showed that individuals with lower FVimb exhibited greater PAPE effects following the PAPE-F protocol (β = 0.63; R2 = 40; p = 0.03), but no significant associations were observed between these two variables for the PAPE-V protocol (R2 = 0.19; p = 0.53).

Discussion

These results suggest that individuals can achieve comparable acute JH improvements using force- or velocity-oriented CAs, although force-oriented CA may promote greater gains in individuals with lower FVimb.

Frequency of Upper Body Muscular Demands in Contemporary and Ballet Dance Performance: A Cross Sectional Performance Analysis

Introduction: There is currently little research relating specifically to the muscular strength and endurance requirements of the upper body such as lifts at varying heights, ground floor contact with the hands and inversions such as handstands. Enhanced understanding of muscular demands can inform training program design to build physical tolerance to meet the demand of the activity. The aim of this study was to ascertain the frequency of upper body muscular skills in contemporary and ballet dance performance. Methods: Analysis of 46 individual ballet performers (F = 23, M = 23) from 12 performances (duration 63.5 ± 44.5 minutes) and 44 individual contemporary performers (F = 21, M = 23) from 12 performances (duration 35.7 ± 4.3 minutes) was carried out. Frequency of upper body skills was recorded using Dartfish Easytag-Note and converted to mean frequency per minute of total performance and per performance by genre and by sex. Differences in frequency between genre were analyzed via Mann-Whitney U. Phase two analyzed differences between sex via Mann-Whitney U. Finally, analysis of differences between sex within dance genre was carried out via Wilcoxon signed rank test. Significance was accepted at P < .05. Results: A significant difference was apparent between ballet and contemporary dance for holding own weight (P < .05) with a greater total mean frequency within contemporary performances of 8.50 ± 9.03 compared to a total mean frequency of 1.51 ± 3.13 within ballet performances. Additionally, there was a significant difference for above shoulder assisted lift (P < .05) when comparing male dancers, with male contemporary dancers carrying out significantly more (9.82 ± 8.56) per performance than male ballet dancers (2.33 ± 4.66). A higher mean frequency of below shoulder lifts than above shoulder lifts was also noted, with the majority of above shoulder lifts remaining at eye level. Conclusion: Training programs must prepare dancers for upper body movements that consider differing biomechanical demands of a variety of lifts and inversions.

Force-velocity-power profiling in flywheel squats: Differences between sports and association with countermovement jump and change of direction performance

The objectives of our study were 1) to examine whether the force-velocity-power (FvP) outcomes in the concentric and eccentric phases of flywheel (FW) squats differ among sports disciplines and 2) to investigate the association between FvP outcome variables and two key sport-performance indicators: countermovement jump height (CMJ) and change of direction (CoD) time involving 90° or 180° turns. Tests were performed by 469 athletes from five different sport disciplines and physical education students. Our results showed that FvP outcomes, when measured during the eccentric phase of the FW squat, effectively differed between athletes from different sports. However, during the concentric phase of the squat, only for the slope variable differences between sports were found. Contrary to our hypothesis, there were no statistically significant correlations between FW squat FvP outcomes and CMJ or CoD test results. These results suggest that FvP outcomes derived from FW squats may lack external validity and cannot be reliably used as a predictor of athletes' jumping and agility performance. The paper discusses possible reasons for the larger differences between sports in eccentric FvP outcomes, as well as the absence of correlations between FvP outcomes and functional tests.

Force-Velocity Profiling in Club-Based Field Hockey Players: Analyzing the Relationships between Mechanical Characteristics, Sex, and Positional Demands

The purpose of this study was to investigate differences between sex and positional demands in club-based field hockey players by analyzing vertical force-velocity characteristics. Thirty-three club-based field hockey athletes (16 males - age: 24.8 ± 7.3yrs, body mass: 76.8 ± 8.2kg, height: 1.79 ± 0.05m; 17 females - age: 22.3 ± 4.2yrs, body mass: 65.2 ± 7.6kg, height: 1.66 ± 0.05m) were classified into two key positional groups (attacker or defender) based on dominant field position during gameplay. Force-velocity (F-v) profiles were established by performing countermovement jumps (CMJ) using a three-point loading protocol ranging from body mass (i.e., zero external mass, 0%) to loads corresponding to 25% and 50% of their own body mass. Across all loads, between-trial reliability of F-v and CMJ variables was determined by intraclass correlation coefficients (ICCs) and coefficient of variation (CV) and deemed to be acceptable (ICC: 0.87-0.95, CV% 2.8-8.2). Analysis by sex identified male athletes had significantly greater differences in all F-v variables (12.81-40.58%, p ≤ 0.001, ES = 1.10-3.19), a more enhanced F-v profile (i.e., greater theoretical maximal force, velocity, and power values), plus overall stronger correlations between relative maximal power (P_MAX) and jump height (r = 0.67, p ≤ 0.06) when compared to female athletes (-0.71≤ r ≥ 0.60, p = 0.08). Male attackers demonstrated a more 'velocity-oriented' F-v profile compared to defenders due to significant mean differences in theoretical maximal velocity (v₀) (6.64%, p ≤ 0.05, ES: 1.11), however differences in absolute and relative theoretical force (F₀) (15.43%, p ≤ 0.01, ES = 1.39) led to female attackers displaying a more 'force-oriented' profile in comparison to defenders. The observed mechanical differences identify the underpinning characteristics of position specific expression of P_MAX should be reflected in training programmes. Therefore, our findings suggest F-v profiling is acceptable to differentiate between sex and positional demands in club-based field hockey players. Furthermore, it is recommended field hockey players explore a range of loads and exercises across the F-v continuum through on-field and gym-based field hockey strength and conditioning practices to account for sex and positional mechanical differences.

Measurement Agreement Between Samozino's Method and Force Plate Force-Velocity Profiles During Barbell and Hexbar Countermovement Jumps

ABSTRACT

Hicks, DS, Drummond, C, and Williams, KJ. Measurement agreement between Samozino's method and force plate force-velocity profiles during barbell and hexbar countermovement jumps. J Strength Cond Res 36(12): 3290-3300, 2022-This study aimed to measure agreement between using Samozino's method and force plates to determine mean force, velocity, and power during unloaded and loaded barbell and hexbar countermovement jumps. Twenty-one subjects performed countermovement jumps against incremental loads using both loading conditions. Ground reaction force was recorded using a dual-force plate system (1,000 Hz) and used as the criterion method to compare with Samozino's method. Reliability and validity was determined by intraclass correlation coefficients (ICCs), coefficient of variation (CV), limits of agreement plots, and least products regression analysis. Samozino's method provided acceptable levels of reliability for mean force, velocity, and power (ICC > 0.90, CV% < 5.5) across both loading conditions. Limits of agreement analysis showed the mean bias was 2.7, 15.4, and 7.2% during barbell countermovement jumps and 1.8, 12.4, and 5.0% during hexbar countermovement jumps for mean force, velocity, and power, respectively. Based on these findings, Samozino's method not only is reliable when measuring mean force, velocity, and power during loaded and unloaded barbell and hexbar countermovement jumps but also identifies limitations regarding concurrent validity compared with the gold standard. Across loading conditions, Samozino's method overestimated mean force (0.5-4.5%) and underestimated mean velocity (11.81-16.78%) and mean power (2.26-7.85%) compared with the force plates. Because of fixed and proportional bias between criterion and predictor, the results do not support the use of Samozino's method to measure mean force, velocity, and power. Therefore, it is not recommended for practitioners to use Samozino's method to estimate mechanical variables during loaded and unloaded countermovement jump actions using a barbell and hexbar.

Effectiveness of individualized training based on force-velocity profiling on physical function in older men

The study aimed to investigate the effectiveness of an individualized power training program based on force–velocity (FV) profiling on physical function, muscle morphology, and neuromuscular adaptations in older men. Forty‐nine healthy men (68 ± 5 years) completed a 10‐week training period to enhance muscular power. They were randomized to either a generic power training group (GPT) or an individualized power training group (IPT). Unlike generic training, individualized training was based on low‐ or high‐resistance exercises, from an initial force–velocity profile. Lower‐limb FV profile was measured in a pneumatic leg‐press, and physical function was assessed as timed up‐and‐go time (TUG), sit‐to‐stand power, grip strength, and stair‐climbing time (loaded [20kg] and unloaded). Vastus lateralis morphology was measured with ultrasonography. Rate of force development (RFD) and rate of myoelectric activity (RMA) were measured during an isometric knee extension. The GPT group improved loaded stair‐climbing time (6.3 ± 3.8 vs. 2.3% ± 7.3%, p = 0.04) more than IPT. Both groups improved stair‐climbing time, sit to stand, and leg press power, grip strength, muscle thickness, pennation angle, fascicle length, and RMA from baseline (p < 0.05). Only GPT increased loaded stair‐climbing time and RFD (p < 0.05). An individualized power training program based on FV profiling did not improve physical function to a greater degree than generic power training. A generic power training approach combining both heavy and low loads might be advantageous through eliciting both force‐ and velocity‐related neuromuscular adaptions with a concomitant increase in muscular power and physical function in older men.

The Effect of 16 Weeks of Lower-Limb Strength Training in Jumping Performance of Ballet Dancers

Jumping ability is considered a determinant of performance success. It is identified as one of the predictors and talent identification in many sports and dance. This study aimed to investigate the effect of 16 weeks of lower-limb strength training on the jumping performance of ballet dancers. A total of 24 participants from the same dance school were randomly selected in the control group [CG; n = 10; aged 13.00 (1.49) years; 43.09 (9.48) kg and 1.53 (0.11) m] and the intervention group [IG; n = 14; aged 12.43 (1.45) years; 38.21 (4.38) kg and 1.51 (0.07) m], evaluated before and after the applied strength training program mainly using the body weight of each participant. Jump performance was assessed using MyJump2, a scientifically validated mobile phone app. Intergroup and intragroup comparisons were assessed, and the magnitude of change was calculated using the effect size (ES). While CG significantly decreased the relative power over time (p < 0.001, ES = −0.29: small), results from the intragroup comparisons suggest that IG significantly increased the countermovement jump (CMJ) height (p < 0.001, ES = 1.21: large), the relative force (p < 0.001, ES = 0.86: moderate), maximal velocity (p < 0.001, ES = 1.15: moderate), and relative power (p < 0.001, ES = 1.37: large). We concluded that a 16-week strength training program of lower limbs is an effective way to improve CMJ height in young dancers. Supplementary strength training appears to be the determinant for the improvement of the jumping performance of ballet dancers.

Effect of Supplementary Physical Training on Vertical Jump Height in Professional Ballet Dancers

Dancers require many specific dance skills of a ballistic nature. The design of supplementary training to improve the strength of the lower limbs and jump height is a relevant area of research. The purpose of this study was (1) to compare the effect of plyometric training versus combined training on countermovement jump (CMJ), squat jump (SJ), and sauté in first position (sauté) height and (2) to observe whether changes in CMJ and SJ were associated with changes in sauté in female and male dancers. Eighty-one classical professional ballet dancers (41 women and 40 men, age = 22.9 [3.7] y, body mass = 59.7 [8.6] kg, height = 167.4 [7.3] cm) were divided into a control group and 2 experimental groups: plyometric training and combined training. All groups followed their common routine of training regarding classes and rehearsal practice, whereas the experimental groups added 2 sessions (1 h per session) for 9 weeks of supplementary training. Significant increases (medium to large effect size) in CMJ, SJ, and sauté height were found in the pretest versus posttest comparisons for both experimental groups. Significant, very large correlations were found between the magnitude of improvement in sauté and the magnitude of improvement in CMJ and SJ. Plyometric and combined training programs are effective ways to improve jumping ability in professional dancers. The improvement in CMJ and SJ has a good transference on sauté `performance. These findings support the use of traditional training methods to improve jump height in specific and nonspecific ballet jumping ability.

Isolated Joint Block Progression Training Improves Leaping Performance in Dancers

The purpose of this study was to investigate the effect of a 12-week ankle-specific block progression training program on saut de chat leaping performance [leap height, peak power (PP), joint kinetics and kinematics], maximal voluntary isometric plantar flexion (MVIP) strength, and Achilles tendon (AT) stiffness. Dancers (training group n = 7, control group n = 7) performed MVIP at plantarflexed (10◦) and neutral ankle positions (0◦) followed by ramping isometric contractions equipped with ultrasound to assess strength and AT stiffness, respectively. Dancers also performed saut de chat leaps surrounded by 3-D motion capture atop force platforms to determine center of mass and joint kinematics and kinetics. The training group then followed a 12-week ankle-focused program including isometric, dynamic constant external resistance, accentuated eccentric loading, and plyometric training modalities, while the control group continued dancing normally. We found that the training group's saut de chat ankle PP (59.8%), braking ankle stiffness (69.6%), center of mass PP (11.4%), and leap height (12.1%) significantly increased following training. We further found that the training group's MVIP significantly increased at 10◦ (17.0%) and 0◦ (12.2%) along with AT stiffness (29.6%), while aesthetic leaping measures were unchanged (peak split angle, mean trunk angle, trunk angle range). Ankle-specific block progression training appears to benefit saut de chat leaping performance, PP output, ankle-joint kinetics, maximal strength, and AT stiffness, while not affecting kinematic aesthetic measures. We speculate that the combined training blocks elicited physiological changes and enhanced neuromuscular synchronization for increased saut de chat leaping performance in this cohort of dancers.

Should We Base Training Prescription on the Force-Velocity Profile? Exploratory Study of Its Between-Day Reliability and Differences Between Methods

PURPOSE

To analyze the differences in the force-velocity (F-v) profile assessed under unconstrained (ie, using free weights) and constrained (ie, on a Smith machine) vertical jumps, as well as to determine the between-day reliability.

METHODS

A total of 23 trained participants (18 [1] y) performed an incremental load squat jump test (with ∼35%, 45%, 60%, and 70% of the subjects' body mass) on 2 different days using free weights and a Smith machine. Nine of these participants repeated the tests on 2 other days for an exploratory analysis of between-day reliability. F-v variables (ie, maximum theoretical force [F0], velocity [v0], and power, and the imbalance between the actual and the theoretically optimal F-v profile) were computed from jump height.

RESULTS

A poor agreement was observed between the F-v variables assessed under constrained and unconstrained conditions (intraclass correlation coefficient [ICC] < .50 for all). The height attained during each single jump performed under both constrained and unconstrained conditions showed an acceptable reliability (coefficient of variation < 10%, ICC > .70). The F-v variables computed under constrained conditions showed an overall good agreement (ICC = .75-.95 for all variables) and no significant differences between days (P > .05), but a high variability for v0, the imbalance between the actual and the theoretically optimal F-v profile, and maximal theoretical power (coefficient of variation = 17.0%-27.4%). No between-day differences were observed for any F-v variable assessed under unconstrained conditions (P > .05), but all of the variables presented a low between-day reliability (coefficient of variation > 10% and ICC < .70 for all).

CONCLUSIONS

F-v variables differed meaningfully when obtained from constrained and unconstrained loaded jumps, and most importantly seemed to present a low between-day reliability.

Force-velocity profiling in athletes: Reliability and agreement across methods

The aim of the study was to examine the test-retest reliability and agreement across methods for assessing individual force-velocity (FV) profiles of the lower limbs in athletes. Using a multicenter approach, 27 male athletes completed all measurements for the main analysis, with up to 82 male and female athletes on some measurements. The athletes were tested twice before and twice after a 2- to 6-month period of regular training and sport participation. The double testing sessions were separated by ~1 week. Individual FV-profiles were acquired from incremental loading protocols in squat jump (SJ), countermovement jump (CMJ) and leg press. A force plate, linear encoder and a flight time calculation method were used for measuring force and velocity during SJ and CMJ. A linear regression was fitted to the average force and velocity values for each individual test to extrapolate the FV-variables: theoretical maximal force (F0), velocity (V0), power (Pmax), and the slope of the FV-profile (SFV). Despite strong linearity (R2>0.95) for individual FV-profiles, the SFV was unreliable for all measurement methods assessed during vertical jumping (coefficient of variation (CV): 14-30%, interclass correlation coefficient (ICC): 0.36-0.79). Only the leg press exercise, of the four FV-variables, showed acceptable reliability (CV:3.7-8.3%, ICC:0.82-0.98). The agreement across methods for F0 and Pmax ranged from (Pearson r): 0.56-0.95, standard error of estimate (SEE%): 5.8-18.8, and for V0 and SFV r: -0.39-0.78, SEE%: 12.2-37.2. With a typical error of 1.5 cm (5-10% CV) in jump height, SFV and V0 cannot be accurately obtained, regardless of the measurement method, using a loading range corresponding to 40-70% of F0. Efforts should be made to either reduce the variation in jumping performance or to assess loads closer to the FV-intercepts. Coaches and researchers should be aware of the poor reliability of the FV-variables obtained from vertical jumping, and of the differences across measurement methods.

Does the initial level of horizontal force determine the magnitude of improvement in acceleration performance in rugby?

This study aimed to observe the effect of 8 weeks of resisted sled training (RST), with optimal loading for maximal power output production and initial levels of force, on the magnitude of improvement in sprint performance and individual sprint mechanical outputs in female amateur rugby union players. The study examined the horizontal Power-Force-Velocity profile (P-F-V profile), which provides a measure of the athlete's individual balance between force and velocity capabilities (S_fv), theoretical maximum force (F₀), theoretical maximum velocity (V₀), maximum power (P_max), the maximum ratio of force (Rf_max) and rate of decrease in ratio of force (D_rf). Thirty-one participants (age = 23.7 ± 3.3years, BM = 69 ± 9Kg, height = 167.5 ± 5.2 cm) were divided into a control group and two experimental groups; forwards (FG) and backs (BG). For 8 consecutive weeks (16 sessions), all groups performed the same training programme: 2 sets of 5 × 30 m, but athletes assigned to FG and BG ran towing a resisted sled attached to their waists, with optimal loading for maximal power output production. Both FG and BG significantly improved (p ≤ 0.05) in 5 and 20 m sprint performance, and in the mechanical properties related to the horizontal P-F-V profile. The correlation between the initial level of horizontal strength and the magnitude of improvement in P_max also suggests that higher levels of horizontal force may lead to greater adaptations in RST. The P-F-V profile is a useful field method for identifying the weakest mechanical variable in rugby players during sprinting and enabling the prescription of individualized training programmes according to specific running performance.