Using the force-velocity imbalance to individualise training
A research review from the Performance Digest
Get instant access to over 1,000 must-know sports science studies without paying a penny. You’ll get the latest research on Strength & Conditioning, Nutrition, Coaching, Recovery, Technology, Rehab, and Youth Development.
By James de Lacy
25th October 2019 | 3 min read
Contents of Research Review
For each individual, an optimal force-velocity (F-V) relationship exists that maximises lower-limb ballistic performance (e.g. vertical jump) and represents the optimal balance between force and velocity qualities. Thus, F-V profiling may provide a more accurate representation of an athlete’s maximal force production capabilities. At this point in time, only one study has investigated the effects of an optimised training program based on individual F-V profiles (see HERE). However, the duration of this study was reasonably short (9 weeks), which may have resulted in only some subjects reaching an optimal F-V profile.
Therefore, the aims of this study were to:
1) Analyse the individual adaptation in F-V profile until every subject reached their optimal profile; and
2) Study the individual F-V profile in response to a three week detraining period.
All sixty subjects (age = 23.7 ± 3.7 yr) were trained professional futsal or semi-professional soccer and rugby players. The squat jump (SJ) was used to determine each subjects F-V profile in a Smith machine. Five to eight progressive loads where used after bodyweight ranging from 15- 90kg.
Subjects were assigned to one of four groups based on their F-V profile in relation to their optimal profile (F-V imbalance). 100% was considered perfectly balanced and the exercise prescription of each group included:
Once the subjects F-V imbalance reached the next groups range, they changed training group. As each got closer to their optimal profiles, F-V profiling was monitored every two weeks then eventually every week. Once a well-balanced profile was reached (defined as 90-110%), targeted training stopped.
HFD and LFD groups:
HVD and LVD groups:
SJ height was significantly correlated with differences in both F-V imbalance (explained variance of 48.2%) and maximal power (explained variance of 37.7%)
Based on the results from this study, it seems the larger the initial deficit, the longer the training intervention needs to be to reach an optimal profile. Furthermore, F-V imbalance change had a greater effect on jump performance than maximal power change. It is important to note that an improvement in maximal power may not incur an increase in jump height, which provides practical significance to coaches looking to maximise jump height with their athletes. This highlights that focusing on reducing the F-V imbalance may provide greater performance improvements when compared to traditional programming.
Rather than a “one-size-fits-all” approach, F-V profiling can provide individual information not only on training content but also training duration. Given the ease of measurement, it could be recommended to monitor F-V profiles regularly to adjust athletes in different groups throughout a training period (e.g. every three weeks). The image below shows the training guidelines for each group. The My Jump 2 app is the easiest, low-cost way of monitoring F-V profiles. SJ’s performed over 4 progressive loads can be performed at the end of the warm-up and will only take approximately 10 min for a small group of athletes. These are the loading guidelines I have used successfully:
Males – 0, 20, 40, 60kg.
Females – 0, 15, 30, 45kg.
To touch on the de-training period in the present study, only one other study has looked at changes in F-V profiles during a tapering period (see HERE). This previous study showed a “performance rebound” (improvement in performance after a de-training period) while the present study did not, which indicates changes in F-V profiles during de-training or tapering may be influenced by prior training. Furthermore, in Issue #32 of the Performance Digest, I reviewed a paper that showed a lot of strength can be retained after a 20 week detraining period. The present study showed all variables can be retained after three weeks of de-training potentially allowing resistance training to be left during small periods of training/competition depending on the sporting culture.
There is one pertinent question that must be asked before embarking on balancing everyone’s F-V profile: Will a well-balanced profile for sports that have positions that require high force or velocity outputs hurt or enhance their sport performance? For example, a prop in rugby union requires the ability to produce large amounts of force during scrummaging. An initial F-V profile will reflect this likely showing a high velocity deficit. Neglecting high-load exercise for the sake of balancing the F-V profile and improving jump performance may leave the athlete lacking in the specific area they need to play their sport well.”
The full study can be read here.
Every coach understands the importance of staying up-to-date with the latest sports performance research like this, but none have the time, energy, or even enjoys spending hours upon hours searching through PubMed and other academic journals. Instead, your precious time is better-spent coaching, programming, and managing all the other more important aspects of your job.
The Performance Digest is a monthly summary of the latest sports performance research reviewed by our team of hand-selected experts. We sift through the 1,000+ studies published in the realms of sports performance every, single month and review only those which are important to you. Each monthly issues contains 19 research reviews in all of the following disciplines:
This comprehensive topic base ensures you’re constantly expanding your knowledge and accelerating your career as quickly as humanly possible. The reviews are also hyper-focused, 1-page summaries, meaning there’s no jargon or wasted time. We cut right to the chase and tell you what you need to know so you can get back to coaching.
Join the thousands of other coaches who read it every, single month. Click here to grab your FREE copy…