Hockey Conditioning: Combating Fatigue

A couple days ago, I outlined a terrific review article on what factors limit repeat sprint performance. If you missed it, you can check it out here: Hockey Conditioning: Understanding Fatigue. Repeat sprint performance, as the authors of that review defined, includes repeated maximum intensity efforts of <10s with <60s rest in between. Most people reading this are probably familiar with the idea that most of you reading this are familiar with the fact that an average hockey shift will fluctuate between ~30-75s depending on the position and level. What many people overlook, however, is that these shifts don’t involve 100% efforts the entire time the player is on the ice. Even the average excessively hyper 11-year-old hopped up on the donut holes and Monster their parents bought them as a pre-game meal couldn’t go 60s at this intensity.

If your son looks like this, he probably doesn’t need another energy drink.

There are inherent physiological mechanisms that will begin to limit performance if a certain intensity is maintained for prolonged periods of time (e.g. 10+ seconds). Elite level hockey players are very efficient at managing their fatigue during a shift. They intersperse periods of all-out efforts with periods of gliding, lighter skating, and repositioning, and when this isn’t possible, they keep their shift short to minimize the accumulated fatigue. Most don’t know they do this; it feels natural to them. For our purposes, the most important thing to recognize here is that a 45s shift is comprised of several significantly shorter high intensity efforts separated by periods of lower intensity efforts and/or stoppages. For this reason, understanding the mechanisms underlying performance decrements in repeat sprint ability is essential, as this is EXACTLY the quality hockey players want to train to ensure that they’re as fast at the start of the game as they were at the beginning.

Today, I want to explore the companion research review article from Bishop et al., 2011, titled “Repeated-Sprint Ability – Part II: Recommendations for Training”.  Before we get into it, I think it’s important to point out that recommendations on how to improve ANY physical quality always need to be kept in perspective. There are psychological, physiological, and training “age” considerations, but even within any combination of those cohorts, there are always appropriate times in the hockey calendar and obligatory progressions leading up to any given training practice; this is especially true of conditioning. My hope is that you won’t simply read “this is the best way to improve repeat sprint ability” and just use the recommendations from this article repeatedly year-round. This will invariably lead to decrements in OTHER physical qualities, which will negatively effect on-ice performance. Everything in training needs to be kept in context.

Training Recommendations to Improve Repeat Sprint Ability (RSA)
The authors kicked off the article by pointing out that having a “good” RSA is more about having a high average sprint speed, than just a low drop-off. In the case of the latter, a marathon runner would have a relatively low drop-off, but their starting speed wouldn’t be very fast, and therefore not adequate within the context of hockey speed. This, again, simply illustrates the trade-off between maximum speed and maximum endurance. Below is a list of take-home points from the article that help explain which types of training will help improve RSA. If you haven’t already, please read this article (Hockey Conditioning: Understanding Fatigue) before continuing on with the list below, as these points may not make sense without understanding how they affect one or more of the RSA fatigue mechanisms!

1. A high-intensity interval training protocol of 6-12 x 2 mins of work at 100% VO2Max, followed by 1 minute of rest can significantly improve PCr (phosphocreatine) resynthesis/replenishment during the first 60s of recovery following a high-intensity effort. This is especially pertinent in light of the fact that NO changes in the rate of PCr resynthesis have been found following an interval training protocol of 8 x 30s of work at 130% VO2Max followed by 90s of rest, a protocol of 15 x 6s of all-out sprinting followed by 60s of light jogging, or a protocol of 4-7 all out 30s efforts followed by 3-4 minutes of rest. The authors pointed out that some of these results may be explained by the fact that other studies used a 3-minute post-exercise PCr check-in point, which may miss the initial changes in a more rapid resysnthesis. That said, the finding of improved PCr resynthesis in the first 60s following the above protocol is an interesting finding.
2. Changes in enzymes that affect anaerobic glycolysis (such as phosphofructokinase and phosphorylase) are greater following a training protocol that involves repeated 30s sprints compared to one that involves repeated 6s sprints or continuous training.
3. Changes in glycolytic enzymes are also greater following high-intensity intervals that are followed by long rest intervals (10-15 minutes) compared to shorter rest intervals (3-4 minutes), probably as a result of higher peak blood and muscle lactate levels with the longer recovery. Taken together, these results suggest the most optimal way to develop anaerobic performance is to train using 20-30s all-out intervals with ~10-minute rest intervals.
4. There is not a linear relationship between VO2Max and various RSA fatigue measures, indicating that the goal should be to train for an “optimal” VO2Max, not necessarily a “maximal” V02Max.
5. Interval training at approximately 100% VO2Max leads to larger increases in VO2Max than continuous training matched for total work, but only if the continuous training is below ~60% VO2Max, otherwise the differences are negligible.
6. Interval training has the added benefits of augmenting other desired adaptations, such as the rate of PCr resynthesis and muscle buffer capacity. The authors recommend performing high-intensity intervals at ~80-90% VO2Max with rest periods that are shorter (e.g. 1 minute) than the work periods (e.g. 2 minutes).
7. A high-intensity interval training protocol of 6-10 x 2 minutes work at 120-140% of the lactate threshold followed by 1 minute of rest increases muscle buffer capacity, but 30 minutes of continuous training at 80-95% of the lactate threshold does not.
8. Excessive accumulation of H+ during training may actually have a detrimental effect on adaptations to the pH regulatory systems within the muscle. This could result from interval training at intensities >100% VO2Max.
9. Taken together, these results imply that the best way to improve muscle buffer capacity is to train using high-intensity intervals at ~80-90% VO2Max with rest periods that are shorter than the work periods (e.g. 2 minutes on, 1 minute off) to ensure that the working muscles are being trained in a moderately lower pH environment.
10. High-intensity interval training leads to better improvements in muscle buffer capacity and Na+/K+ pump isoform content compared to repeated-sprint training, which has shorter sprint durations at higher intensities with longer rest periods.
11. However, repeated-sprint training leads to better improvements in best sprint time and mean sprint time compared with interval-based training.
12. Interestingly, although not overwhelming, 10-weeks of training 2x/week using small area soccer games (2-4  reps of 2.5-4 minute games) lead to a ~4% improvement in best and mean sprint times during an RSA test, which was the same as an interval training protocol of 12-24 x 15s of work at 105-115% VO2Max followed by 15s of rest.
13. A resistance training protocol involving 2-5 sets of 10-15 maximal repetitions lead to comparable increases in mean work performed during a RSA test (~12%), compared to a high-intensity interval training program (~13%), and a sprint training program (~12%). Resistance training also lead to a ~8-9% increase in first-sprint performance, and ~20% improvement in the sprint decrement score.
14. Greater improvements in RSA have been founding using resistance training protocols that involve 20s of rest between sets, compared to 80s of rest, despite less improvements in maximum strength (20 vs 46%), probably due to the increases in metabolic byproduct accumulation with the shorter rest periods.

Take Home Points
As I mentioned in the intro, it’s always important to understand exactly what physical quality you’re seeking to improve with your training, and to put that within context of the whole training program. The evidence above suggests that one of the better ways to improve RSA is through training with a protocol of 6-10 x 2 minutes of work at ~80-100% VO2Max followed by 1 minute of rest, and with resistance training exercises using relatively high reps and short rest intervals. These things lead to improvements in the rate PCr resynthesis, glycolytic enzymes, muscle buffer capacity, and V02Max, all of which should benefit RSA performance.

While hockey is a very lactate-driven sport, I think there is much to be gained from maximizing the alactic and aerobic systems to minimize the lactic load associated with any given shift. Because the anaerobic-lactic system is associated with significant decrements in performance and longer recovery times, utilizing the “surrounding systems” in the anaerobic-alactic and aerobic systems to the greatest extent possible will likely allow the player to maintain a high level of performance for a longer period of time. This will not only translate into finishing a period strong, it will also translate into finishing a game and even a series of games strong. With this in mind, the improvements in PCr resynthesis (which can be considered a “fuel” for the anaerobic-alactic system) and VO2Max (which is a decent marker of aerobic capacity) are especially appealing.

Ultimately, it’s elite-level conditioning that allows players to exhibit their elite level skill, consistently.

To your success,

Kevin Neeld

P.S. Don’t forget to check out Ultimate Hockey Training, which covers year-round hockey conditioning principles in detail and provides a ton of implementable training progressions!

Reference:
Bishop, D., Girard, O., & Mendez-Villaneuva, A. (2011). Repeated-Sprint Ability – Part 2: Recommendations for Training. Sports Medicine, 41(9), 741-756.

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