It’s great to be back in the gym after a relaxing weekend. My mom came to visit Emily and I from Raleigh, NC so it was nice to have some down time to hang out with her. As you can imagine, my schedule keeps my pretty busy, so I don’t get to spend as much time with friends and family as I’d like!
As I mentioned last week, I’ve been reading quite a bit of research on energy systems recently. Understanding where energy for certain activities comes from will help make training more specific and appropriate to the demands of the sport (and the position in some cases). In general, it is traditionally thought that:
Naturally, this is a grossly oversimplified view of energy systems training, which is the major reason for this discussion. It’s important to realize that the intensity of movement is equally, if not more important in determining energy system contribution than the duration of the activity. In other words, if you walk for 12 seconds, you won’t be relying on the ATP-PCr System as your primary energy source; it’s a low intensity activity that doesn’t require a huge surge of energy production. As your body performs work, it breaks down ATP. Replenishment of ATP is needed to continue to do work. Naturally, the higher the intensity of the activity, the faster the breakdown of ATP and therefore, the faster the replenishment source needs to be. This is why high intensity activities rely on the ATP-PCr system; it’s the fastest replenishment source. Unfortunately, this supply is limited, so as stores become depleted, the body must rely on other energy systems for the replenishment of ATP. Because these other systems cannot replenish ATP as rapidly, performance decreases. This is an underlying reason why someone can run a 4.3s 40-yard dash (120 feet at 27.9 ft/second), but not a 3:09 mile (5,280 feet at 27.9 ft/second). Simply, the rate at which energy can be resupplied is a limiting factor in maintaining high level performance.
After reading the above paragraph, it’s reasonable to think that the systems are activated in the presented sequence; the next being activated when the former is depleted. In other words, Anaerobic Glycolysis System becomes active when the ATP-PCr System depletes, the Aerobic Glycolysis System becomes active when the Anaerobic Glycolysis System depletes, and so on. In fact, this isn’t too far off of how this is typically presented in undergraduate academic programs. In reality, almost ALL systems are always active to some degree during every activity and preceding activity will play a role in which system predominates.
One illustration of this comes from a 1999 study from Parolin et al. titled “Regulation of skeletal muscle glycogen phosphorylase and PDH during maximal intermittent exercise.” As an aside, I find that I’m a little embarrassed when research of this magnitude is over 10 years old before I come across it!
The study looked at the contribution of ATP regeneration from PCr, glycolysis, and oxidative (aerobic) systems during a repeat high intensity sprint task. More specifically, the subjects were asked to perform 3 30-second maximum effort cycling sprints at 100 RPMs, separated by 4 minutes of rest. The authors compared the first and third cycling effort using the following time periods:
What they found was fascinating.
This is just a snapshot of a myriad of results from the authors’ analyses, but taken together this study demonstrates:
In other words:
Again, there is much more discussion to be had on the methods and results of this study, but it provides reasonable evidence for the importance of developing aerobic systems even in sports that are seemingly anaerobic dominant, such as ice hockey. As I’ve alluded to in the past, there are appropriate times of year and methods to develop this system, but the idea that hockey players ONLY need to do high intensity intervals from 30-45s is just as misguided as the idea that they only need to go for long jogs or bike rides to develop their conditioning.
To your success,
P.S. Special thanks to Joel Jamieson for directing me to this study.
P.S.2. If you want a structured off-ice hockey conditioning system, check this out: Ultimate Hockey Training!
Parolin, M., Cheseley, A., Matsos, M., et al. (1999). Regulation of skeletal muscle glycogen phosphorylase and PDH during maximal intermittent exercise. American Journal of Physiology, 277: E890-900
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Kevin has rapidly established himself as a leader in the field of physical preparation and sports science for ice hockey. He is currently the Head Performance Coach for the Boston Bruins, where he oversees all aspects of designing and implementing the team’s performance training program, as well as monitoring the players’ performance, workload and recovery. Prior to Boston, Kevin spent 2 years as an Assistant Strength and Conditioning Coach for the San Jose Sharks after serving as the Director of Performance at Endeavor Sports Performance in Pitman, NJ. He also spent 5 years as a Strength and Conditioning Coach with USA Hockey’s Women’s Olympic Hockey Team, and has been an invited speaker at conferences hosted by the NHL, NSCA, and USA Hockey.