Search Results

Recent studies have brought new insights into the evaluation of power-force-velocity profiles in both ballistic push-offs (eg, jumps) and sprint movements. These are major physical components of performance in many sports, and the methods the authors developed and validated are based on data that are now rather simple to obtain in field conditions (eg, body mass, jump height, sprint times, or velocity). The promising aspect of these approaches is that they allow for more individualized and accurate evaluation, monitoring, and training practices, the success of which is highly dependent on the correct collection, generation, and interpretation of athletes’ mechanical outputs. The authors therefore wanted to provide a practical vade mecum to sports practitioners interested in implementing these power-force-velocity–profiling approaches. After providing a summary of theoretical and practical definitions for the main variables, the authors first detail how vertical profiling can be used to manage ballistic push-off performance, with emphasis on the concept of optimal force–velocity profile and the associated force–velocity imbalance. Furthermore, they discuss these same concepts with regard to horizontal profiling in the management of sprinting performance. These sections are illustrated by typical examples from the authors’ practice. Finally, they provide a practical and operational synthesis and outline future challenges that will help further develop these approaches.

Background: Approach speed is a major determinant of pole-vault performance. Athletic jump events such as long jump, triple jump, and pole vault can utilize an elevated track for the runway. Feedback from athletes indicates a benefit of using an elevated track on their results. However, there is no evidence that elevated tracks increase athletes’ performance. Purpose: To investigate the potential advantage of using an elevated track during elite pole-vault competitions on run-up speed parameters. Methods: Performance and run-up criteria (speed, stride rate, contact, and aerial time) were measured from 20 high-level male pole-vaulters during official competitions on either a regular or an elevated track. Parameters comparisons were made between both conditions, and run-up parameters were confronted to speed modification on the elevated track. Results: Statistical analyses indicated that for the elevated track, there was a small improvement in final speed (1.1%), stride rate (1.1%), and takeoff distance (3.1%) and a small reduction in aerial time (−1.9%). The study highlighted different individual responses depending on athletes’ capabilities. The authors noted that speed improvement was largely correlated with stride-rate improvement (r = .61) and contact-time reduction (r = −.51) for slower athletes. Conclusions: Elevated tracks can increase final approach speed in pole vault and positively influence performance. Interindividual responses were observed in these findings.

The purpose of this investigation was to analyze the validity of an iPhone application (Runmatic) for measuring running mechanics. To do this, 96 steps from 12 different runs at speeds ranging from 2.77–5.55 m·s⁻¹ were recorded simultaneously with Runmatic, as well as with an opto-electronic device installed on a motorized treadmill to measure the contact and aerial time of each step. Additionally, several running mechanics variables were calculated using the contact and aerial times measured, and previously validated equations. Several statistics were computed to test the validity and reliability of Runmatic in comparison with the opto-electronic device for the measurement of contact time, aerial time, vertical oscillation, leg stiffness, maximum relative force, and step frequency. The running mechanics values obtained with both the app and the opto-electronic device showed a high degree of correlation (r = .94–.99, p < .001). Moreover, there was very close agreement between instruments as revealed by the ICC (2,1) (ICC = 0.965–0.991). Finally, both Runmatic and the opto-electronic device showed almost identical reliability levels when measuring each set of 8 steps for every run recorded. In conclusion, Runmatic has been proven to be a highly reliable tool for measuring the running mechanics studied in this work.

Purpose: To analyze the reliability and validity of a field computation method based on easy-to-measure data to assess the mean force ( $\overline{F}$ ) and velocity ( $\overline{v}$ ) produced during a ballistic bench-press movement and to verify that the force–velocity profile (F–v) obtained with multiple loaded trials is accurately described. Methods: Twelve participants performed ballistic bench presses against various lifted mass from 30% to 70% of their body mass. For each trial, $\overline{F}$ and $\overline{v}$ were determined from an accelerometer (sampling rate 500 Hz; reference method) and a simple computation method based on upper-limb mass, barbell flight height, and push-off distance. These $\overline{F}$ and $\overline{v}$ data were used to establish the F–v relationship for each individual and method. Results: A strong to almost perfect reliability was observed between the 2 trials (ICC > .90 for $\overline{F}$ and .80 for $\overline{v}$ , CV% < 10%), whatever the considered method. The mechanical variables ( $\overline{F}$ , $\overline{v}$ ) measured with the 2 methods and all the variables extrapolated from the F–v relationships were strongly correlated (r ² > .80, P < .001). The practical differences between the methods for the extrapolated mechanical parameters were all <5%, indicating very probably no differences. Conclusion: The findings suggest that the simple computation method used here provides valid and reliable information on force and velocity produced during ballistic bench press, in line with that observed in laboratory conditions. This simple method is thus a practical tool, requiring only 3 simple parameters (upper-limb mass, barbell flight height, and push-off distance).

Velocity strength training requires exercise modalities that allow athletes to reach very high movement velocity, which is limited during vertical movements involving body weight. Purpose: To quantify the mechanical outputs developed during horizontal squat jumps (HSJs), notably the movement velocity, in comparison with vertical squat jumps (SJs) with and without loads. Methods: Thirteen healthy male athletes performed SJs without additional loads (SJ₀) and with a load of ∼60% of body mass (SJ₆₀), and during HSJs performed lying on a roller device with (assisted HSJ [AHSJ]) and without (HSJ) rubber-band assistance. Instantaneous lower-limb extension velocity, force, and power output were measured and averaged over the push-off phase. Results: The force was significantly higher during SJ₆₀ than during SJ₀, which was higher than during HSJ and AHSJ. Extension velocity was significantly different across all conditions, with 0.86 (0.07), 1.29 (0.10), 1.59 (0.19), and 1.83 (0.19) m·s⁻¹ for SJ₆₀, SJ₀, HSJ, and AHSJ conditions, respectively. Differences in force and velocity values between SJ₀ and the other conditions were large to extremely large. Differences were observed in power values only between SJ₆₀ and SJ₀, SJ₆₀ and AHSJ, and SJ₀ and HSJ. Conclusions: HSJ modalities allow athletes to reach very to extremely largely greater lower-limb extension velocities (HSJ +24.0% [16%], AHSJ +42.8% [17.4%]) compared to those achieved during SJ₀. HSJ and AHSJ modalities are inexpensive and practical modalities to train limb-extension velocity capabilities, that is, the ability of the neuromuscular system to produce force at high contraction velocities.

Purpose: This study aimed to determine relationships between parameters of force-production capacity in sprinting and opposition skill efficiency in rugby union games according to position. Methods: The sprint force–velocity profile of 33 professional rugby union players divided into 2 subgroups (forwards and backs) was measured on a 30-m sprint. Skill efficiencies (in percentage) of offensive duels, tackles, and rucks were assessed using objective criteria during 12 consecutive competitive games. Pearson correlation was used to determine the relationships between parameters of horizontal force-production capacity in sprinting (maximum propulsive power, theoretical maximum force [F ₀], theoretical maximum velocity, maximum ratio of horizontal force [RF_max], and rate of decrease of this ratio of forces with increasing velocity) and skill efficiencies. Two multiple linear regression models were used to observe whether skill efficiencies could depend on determinants of horizontal force application in low- or high-velocity conditions. A first model including F ₀ and theoretical maximum velocity was used as a macroscopic analysis, while a second model including RF_max and rate of decrease of this ratio of forces with increasing velocity was used as microscopic analysis to determine the most significant determinants of skill efficiency. Results: All skill efficiencies were strongly correlated with maximum propulsive power in forwards and backs. In forwards, F ₀ and RF_max were the key predictors of dueling, rucking, and tackling efficiency. In backs, F ₀ was the main predictor of dueling and rucking efficiency, whereas RF_max was the key predictor of dueling and tackling efficiency. F ₀ and theoretical maximum velocity equivalently contributed to tackling performance. Conclusions: In rugby union forward and back players, skill efficiency is correlated with maximum propulsive power and may be more explained by horizontal force-production capacity and mechanical effectiveness at lower velocities than at higher velocities.