Using Pneumatic Resistance
📝 Weekly paper summary
David Michael Frost
A comparison of the kinematics, kinetics and muscle activity between pneumatic and free weight resistance (Frost et al., 2008)
Category
Cross-sectional study
Context
When training to improve the rate of force development or attain speed-related training adaptations, people will typically lift lighter relative loads to move at faster velocities. However, a challenge with lifting lighter loads very quickly is that individuals spend most of the repetition (more than 50% in some cases) decelerating the load to compensate for the barbell's momentum. Grooving this movement pattern of decelerating during high-velocity training can be problematic. Improving jumping, sprinting, or throwing performance necessitates that the performer is actively accelerating through the entire propulsion phase, not decelerating at the critical moments of the movement.
To combat this, people have suggested using ballistic movements (e.g., throwing the barbell) so the athlete can accelerate for the entire duration of the movement rather than spend so much time decelerating. However, ballistic movements can be difficult or dangerous to perform in most gym environments. An alternative approach would be to use an external load comprised primarily of resistance generated by air pressure (i.e., pneumatic resistance). The advantage of using pneumatic resistance is that because the performer is lifting (virtually) no mass, there is (nearly) no momentum. Therefore, when moving at high velocities, there is no momentum that the individual needs to decelerate. Thus, it's conceivable that pneumatic resistance can provide the benefits of performing ballistic exercises (such that individuals are not grooving a movement pattern where they are decelerating) while alleviating the safety concerns of actually throwing a load.
Therefore, the purpose of this investigation was to examine the kinematics, kinetics, and muscle activity of individuals when performing a bench press with free-weight (either non-ballistically or ballistically) versus pneumatic resistance.
Correctness
There's undoubtedly one interesting part of this study to verify that all participants performed the ballistic exercises with maximal intent. In this study, individuals lifted relative loads ranging from 15-90% of their one-repetition maximum. Therefore, you might wonder how participants felt comfortable throwing a 90%1RM load (or how this even received ethics approval). The answer is that the researchers had a big magnetic particle break that prevented the barbell from crashing down on participants!
If I'm being picky about this study, there are two things I would question. First, I'm unsure what having the barbell "power" data adds to the analysis. I think having information regarding the force and velocities would have been sufficient.
Second, with the introduction of more modern statistical techniques, it becomes easy to look back on some of this older work and see scenarios for improvement. For example, it would have been interesting to use statistical parametric mapping to compare the participants' force and velocity time series instead of just the peaks. There's not much we can fault the authors for about this because they did the best they could at the time, but it's still something to be aware of when interpreting the results.
Contributions
- When lifting the same %1RM, individuals moved fastest when lifting the pneumatic loads; however, movement velocity during the final 10% of the concentric phase when lifting lighter loads was higher for the ballistic bench press versus the pneumatic bench press.
- When lifting the same %1RM, individuals produced more force when performing the ballistic repetitions with free weights (pneumatics and traditional free-weight were similar except for about the last 10% of the repetition, where force falls off drastically for the traditional free-weight bench press). The forces produced when lifting pneumatic resistance were lower relative to conventional free-weight.
- Pneumatics can provide a promising alternative for promoting high velocity-specific training adaptations without the potential safety concerns associated with performing ballistic activities
🧠 Fun fact of the week
When we think of deadly animals, we usually think of large predators. However, the deadliest animal in the world is the mosquito!
🎙 Podcast recommendation
I know I've been giving you a lot of Peter Attia recently, but given how limited I know about the eye going into this one, I found it interesting and think you will too!
🗣 Quote of the week
"Science cannot study what it canot measure accurately and cannot measure what it does not define"
- Quote taken from Implementation Matters: A Review of Research on the Influence of Implementation on Program Outcomes and The Factors Affecting Implementation by Durlak and DuPre (2008; pg. 342)