Original article written by John Harry, John Krzyszkowski, Katie Harris and colleagues
Background
If you know me, or have had the misfortune of being stuck with me for a prolonged period of time, you will know that I love all things strength and power. Furthermore, you will also probably know that I enjoy new methods of training prescription that account for individual differences and help to attain improved physical qualities. I’m a firm believer that we’re all different and one training methodology, load, or volume will not optimise training for everyone. Consequently, when I saw the recent work led by John Harry accepted into the Journal of Strength and Conditioning Research, I thought this would be a great paper to review.
What the authors did
In this paper, Harry et al., [1], provided an explanation for monitoring or prescribing ballistic exercise intensity according to an athlete’s system momentum during the jump squat.
What the authors found
In this study, the authors demonstrated that the magnitude of momentum at take-off was greater in all loaded jumps compared with the unloaded jumps (which is due to the greater mass on the bar). Furthermore, just from eye-balling the data provided, it’s clear the athletes included had very different load-velocity profiles (particularly participant two, who’s health I’m worried for!!) which is a normal occurrence in testing and profiling.
While there’s a bit of discussion around ‘ideal’ training loads, I am a little wary of stating that this is truly the case because there’s so many factors that determine ‘ideal’. Furthermore, after running some basic stats, the load that enables the greatest momentum from the group average data seems to be a bit hard to establish (somewhere in the 15-45% of 1RM range), and from simulating some of the individual data, it’s probably a little difficult to state if a small increase was indicative of a significant increase in momentum. Nonetheless it’s an interesting read and theoretical concept and I look forward to seeing where the group goes with this next.
Limitations
While an interesting Technical Report, I will note there’s a couple of limitations that make me hesitate before implementing this method with my athletes. First, I think it’s important to acknowledge that there’s no one ‘ideal’ load for developing jump performance. To optimise performance, athlete’s require exposure to a range of loads, velocities, and fatigue to enhance performance. While I don’t think the authors are suggesting that only one load should be trained with, by identifying the peak output you only identify one load. Conversely, it’s important to remember that with velocity-based methods (which was stated to be less applicable than momentum-based methods), practitioners can accurately prescribe intensity from a load-velocity profile, and this can be used to target a range of intensities which is important for ballistic development. Additionally, velocity can be used to mitigate undue fatigue by guiding the termination of exercise (discussed in the next point) [2]. Second, I think there may have been a slight misinterpretation of the velocity-threshold work that was used to justify some statements (particularly that of Pérez-Castilla, García-Ramos [3]) as there’s considerable discussion around 10-20% thresholds and finding loads that caused this magnitude of reduction. Briefly, velocity-loss thresholds in the work by Pérez-Castilla, García-Ramos [3] was used to determine the amount of training volume and fatigue that was induced during a set rather than finding a specific load – which was already established through a given velocity [3]. Therefore, this leads to a bit of ill-conceived discussion around finding loads that meet this amount of velocity loss and perhaps caused some of the confusion around what was most applicable. Third, while it’s an interesting method, I am a little worried what would happen with some individuals and whether it would truly optimise training outcomes. For example, if an athlete presented with a steep load-velocity profile (i.e., they were really explosive but relatively weak), their ‘ideal’ load would be skewed towards the lighter end of the spectrum (e.g., 15% of 1RM). However, training methodology would suggest that rather than doing more light ballistic work, the individual would likely need to focus on more concentric force orientated work. Just a thought and when I model this with data from my own lab, it appears to be the case!
What this means for coaches
The use of momentum for prescription is certainly a fascinating concept and it’s great to see new ways to prescribe training for athletes emerging. If a coach can justify its use based off the biomechanics/physics/physiology, then it may well be a useful tool. Personally, I’ll still be using velocity to help support jump squat prescription as the load velocity profile is remarkably linear and we can use it to accurately expose athletes to a range of intensities which is an important consideration for athletic development. However, all training methods are simply a ‘tool in a toolkit’ and you should use whatever method best suits your needs.
Reviewer’s comments
The work by Harry et al [1] is an intriguing concept and I’m hoping to see some well-controlled training data from their group to help support some of the statements within this manuscript. In the meantime, pray for participant two from this study. With a terminal velocity (V1RM) of ~0.27m∙s-1 in the back squat consistently reported in the literature [4], having a mean take-off velocity of 0.36 in a 60% jump squat doesn’t bode well for them…!
Recommended resources
Read – Momentum: a practical solution to calculate the optimal load for resisted sled sprint training – Peter Tierney and colleagues