Of course there could be a million studies in here.. There are some other VJ studies in the other topics, but regardless, any study related to vertical jump can be put in here.



1. The influence of squat depth on maximal vertical jump performance





2. Effects of ballistic training on preseason preparation of elite volleyball players.







3. INFLUENCE OF TRAINING BACKGROUND ON JUMPING HEIGHT

wow squid would probably get a massive erection if he discovered that the rfd wasnt important in jumping.

very nice article, quick overview & nice comparison charts.. very useful.

peace!

yup, regardless of explosive work, excessive strength work can still cause decreases in RFD, especially when the weights get very big. If one is allowed to move heavy weight slowly, then those gains in strength won't translate well to improving explosive strength, at all, in fact it will hurt it.. for example, say you squat 2xBW in 2s, well, if you become squat-obsessed and end up squatting 2.5xBW in 5-6 seconds, those gains in maximal strength past 2x probably won't transfer well to explosive movements.. an emphasis on bar speed has to be there, otherwise you're just training slow like a power lifter.. oly lifters with huge squats, usually do them very fast.. check the 69kg lifter thread in the oly lifting subforum, boevsky 3.6xBW squat, very fast.. then check his oly lifting performance.. just clean's the bar like it's nothing.. so ya that power translates, but obviously, if he had a 3.6xBW PL squat that takes 5+ seconds, that power definitely wouldn't be there in his oly's/explosive movements.

pc

Agreed. However, consider this possibility:

Athlete A:

Squats 2.0xbw in 2s

Three months later

Squats 2.5xbw in 4s
Squats 2.0xbw in 1.75s

I think going from a 2xbw squat to a 2.5xbw squat is more effective in increasing the amount of time it takes to squat 2xbw (in terms of how long the rep takes) versus incorporating RFD work and not increasing to a 2.5xbw squat.
Not only that, but the RFD work may fade away over time once you switch to more strength oriented work, and you wouldn't be able to keep up with that 2xbw squatting speed.

I prefer strength work over RFD work pretty much all the time. Plyos, on the other hand, are a bit of a different story imo (yes I know they increase RFD as well).

well sure but i'm talking incorporating RFD work WHILE you increase to 2.5xBW squat.. i'm saying that has to be utilized, to make sure squat gains always have a speed emphasis.. explosive RFD work while utilizing max strength methods, results in faster reps than if you had just been squatting alone, at least that's been my experience and what i've seen in the field..



to me, it's not about it 'fading', it's about using it as a constant tool to stimulate/potentiate better squat/jump sessions.

sure it fades fast, but that's because the body 'wants to get slower' to lift more weight.. it's a highly type IIa low velocity stimulus.





yes most of us need strength work more than pure rfd work, that's if we had to choose.. but i'm for both concurrently.

ya plyos are still RFD work.. for resistance RFD work, I like REA squat, jump squat, and/or REA low squat ankle hops.

really love those REA LSAH's.

pc

well I prefer reactive/plyos over traditional rfd work (jump squat, oly's), for sure, but traditional rfd work is more necessary for people who are interested in SVJ.

regardless, depth jumps can still improve SVJ.. other reactive work, for example, bounds & other rebounding drills, are less effective at increasing RFD without considerable preloading..

so, if you're more into RVJ (short run ups or full), then ya, you could definitely just focus completely on reactive work.. your more intense exercises would be:

- depth jumps & single leg bounds

Accessory reactive work would be:
- MR drills (half tucks, pogos, double leg bounds)
- jump rope/sprints

so, when it comes to generating forces without considerable preload, oly's/jump squats/rea squat etc will yield more gains.

pc

add these to index when you get "unlazy":



http://www.springerlink.com/content/w0281m2811x34132/


A work-energy approach to determine individual joint contributions to vertical jump performance

C. L. Hubley and R. P. Wells

Abstract
A work-energy approach was used to determine the contributions of the muscles crossing the hip, knee and ankle joints to the total positive work done during maximal vertical jumps. It was found that the average relative contributions of the ankle and hip muscles were approximately 23 and 28% respectively, with the remaining 49% of the work being done by the muscles acting at the knee joint. The efficiency of jumping, i.e. the ratio of potential energy gained to the net mechanical work done by the muscles acting at the three lower limb joints was nearly 1.0. These results stress the importance of all three major leg extensor muscle groups to the performance of an explosive activity such as vertical jumping. It is suggested that the work-energy approach supplies useful information concerning joint contributions without the problems associated with other techniques.
















Title:    Performance of a two-foot vertical jump: What is more important hip or knee dominance?
Authors:    Patel, Rupesh
Keywords:    vertical jump
strategy
performance
hip
knee
core
Approved Date:    22-Dec-2010
Date Submitted:    22-Dec-2010
Abstract:    Vertical jumping ability is an important fundamental skill for many athletic activities. The present work is focused on developing an understanding of the role of various movement strategies on vertical jump performance. The overall objective of this study was to determine if higher hip than knee joint contribution was more effective in enhancing vertical jump height. Additionally, the study explored possible links between the muscle activity and mechanical outputs, and to develop understanding of the role of the lumbar spine and hip. Twenty male university varsity athletes performed ten repetitions of three jumping strategies: preferred, hip dominant and knee dominant. Kinematics, kinetics and muscle activity of the lower limb and trunk were collected. The main observation was that the vertical jump height was positively associated with higher hip than knee work done. However, the within-subject comparisons between the trained hip and knee dominant tasks did not provide additional support for the importance of the hip. Higher hip work appeared associated with greater biceps femoris than gluteus maximus activity. The knee work increased with higher activity of the vastus lateralis and rectus femoris. Finally, higher trunk muscle activity and tighter coupling were associated with the vertical jump height and the max force. This study provides some evidence that encouraging hip dominance together with higher spine stiffness may improve two-foot vertical jump performance. This work has potential implications for training protocols that may be used to improve vertical jump performance.
















Time-of-day effect on patella tendon stiffness alters vastus lateralis fascicle length but not the quadriceps force–angle relationship

    * N.L. Gladys Onambele-Pearson
            Affiliations
          o Institute of Biophysical and Clinical Research into Human Movement, Department of Exercise and Sport Science, Manchester Metropolitan University, Hassall Road, Alsager, England ST7 2HL, UK
          o Corresponding Author InformationCorresponding author. Tel.: +441612475594; fax: +441612476375.
      email address
    * , Stephen J. Pearson
            Affiliations
          o Centre for Rehabilitation and Human Performance Research, Directorate of Sport, University of Salford Manchester, England M6 6PU, UK

Accepted 4 April 2006. published online 10 July 2006.

    * Abstract
    * Full Text
    * PDF
    * Images
    * References

Abstract
Aim

To examine the time-of-day (TOD) effect on torque–force/angle, fibre length (FL), tendon stiffness (K), stress, and strain using the quadriceps muscle–tendon complex as a model.
Methods

Twelve healthy young men (aged 27±2.0 years) were studied at AM (7h45) and PM (5h45). Maximal isometric contractions were carried out on an isokinetic dynamometer, with real-time recordings of vastus lateralis (VL) FL and patella tendon K using B-mode ultrasonography. Percutaneous electrical twitch doublets superimposed on maximal torque were used to test for muscle activation capacity (AC).
Results

At PM, torque and force increased by 16±3.0% () over 30–90° knee angles. Where the load was standardised (at 250N) in order to discriminate between torque generation capacity and tendon K changes, PM relative to AM, there were 8% and 13% () reductions in relaxed and contracted FL, respectively. Average K decreased by 21% () and the maximal stress and strain were increased at PM by 11% and 16%, respectively (). No TOD effect on AC was seen.
Conclusion

The quadriceps torque or force–angle relationships shift upwards at PM vs. AM, with no shift in the position of the optimal knee angle. This torque or force increase appears not to be centrally modulated. Although K decreases with TOD thereby potentially shortening the working length of the sarcomeres, these changes overall do not affect the ability of the muscle to produce greater torque in the evening.