Sprints & Sprinting: A Further Examination

Admit it. It's kind of refreshing isn't it? The wind whipping against you as each muscle group works in swift synergy while you power along like some kid who just knocked off a 7-11.

Sure, there's the burn deep down in your lungs and the inevitable fatigue that even the best of us occasionally succumb to during our more difficult roadwork sessions, but there's also quite a bit of gain to be derived from that pain, especially when you really start getting it all shored down - the integrated, sprint - incorporating split, the proper form and technique, and the right strategies and techniques for reaping the most out of your sprint sessions.

So what am I going to contribute to the vast wealth of sprint savvy, sagacity, and know-how already out and about in various training circles, methodologies and programs? Yeah. So ... how 'bout them Sox? But with all seriousness, what I'm looking to do with this sequel of sorts is incorporate several different proximate bodies of theory involving sprinting and sprint-training into a single, comprehensive 'Sprinting how-to' for the bodybuilder and/or fitness-minded reader. So without further ado, let's get this bad-boy off and running.

Finding Your Ying Yang With Tha' Sprint Thang

Now this is where it gets tricky. On one hand, improving mobility, flexibility and anaerobic endurance threshold will obviously improve one's sprinting.

However, since we're using sprinting as one of several different interrelated means to an end, we need to strike a delicate balance between honing our sprinting abilities in said specific mean without diminishing ourselves in other areas which might ultimately hinder our progression toward that oh-so-money end (re: "being swole").

But as I said before, there's a little more to it than simply going out, hauling ass until hyperventilation sets in, and then stopping for a bit to breathe into a paper baggy. So let's break it down.

Sprinting With An Emphasis On Fat Loss

As I demonstrated in Part I, pretty much any form of consistent sprint training will result in adaptive modifications to skeletal muscular metabolism which will promote fatty-acid oxidation and favorable nutrient partitioning. Yeah, "sprinting good for fat loss" - big surprise, I know. So we're going to mold a little meat onto the maxim, because honestly, we know a bit more than that - and we can do better.

First off, different diets and training regimens work for different people, with each offering its own benefits and shortcomings. Unfortunately, this also means I really can't make 'blanket' recommendations regarding sprint training, because a drug-free carb cycling dieter and a steroid using HST dieter have far different parameters and potential for incorporating sprint work into their split. Even two 'regular dieters' would have far different capacities for sprint work if one was doing a ketogenic diet and the second a high carb, low fat diet.

Still, for the sake of this article not deforesting a small South American province every time somebody goes to print a copy, I'm essentially going to assume you are either:

1. Following a cyclical diet with periods of low or no carbs interspersed with infrequent, planned carbohydrate over-feedings or carb-ups.

2. Following a traditional high-protein, moderate carb, roughly isocaloric and reduced calorie diet.

For a genetically average drug-free athlete looking to lose weight who is already strength training 3-to-4 times per week, you should really be performing two (perhaps only one; three if you're really willing to push it) HIIT sessions in a given 7-day split.

Shorter, Repetitive Interval Sprinting Session

Personally, I feel one session should involve shorter, repetitive interval sprinting at 90-95% intensity with a work: rest ratio of somewhere between 1:2 and 1:5, depending on trained state. This could be as simple as 10-15 second (or 80-100m) sprints performed 8-12 times, with walk or jog recovery.

This weekly session will prompt high levels of AMPk activation (especially throughout the lower body) to optimize cellular and enzymatic activity conducive to fat-burning, and also stimulate more long-term augmentative adaptations in terms of mitochondrial biogenesis and glycogen-storage potential.

Second Session

For our second session, we're going to lengthen our intervals while slightly decreasing work intensity so that we're performing our intervals at about 85%-90% of VO2max/perceived maximum potential exertion. These are anaerobic-glycolytic sprints, 200-400m in length. Aim to keep rest intervals between 1-2 minutes.

Note:

I'm just going to come right out and say that 400m should be considered significantly superior in efficacy compared to 200m sprints, but be forewarned, doing 400m repeats is kind of like taking a caning to the lungs, so I'd much rather you train at your own initial fitness level rather than prefontaining yourself into the ER on the first day of your diet.

Sprint-Induced AMPk

'Wait,' I'm sure some of you are asking; 'didn't you just say a few issues back that virtually all cellular AMPk signaling is triggered in response to the first few seconds of the sprint? Why in god's name would I want to keep going for that long?' Well mi amigo, the answer is simple. Sprint-induced AMPk activation triggers a lot of fat-burning; sprint-induced AMPk activation in glycogen depleted or semi glycogen depleted states triggers significantly more.

In fact, it has been conclusively demonstrated that systemic fat oxidation increases both at rest and during aerobic exercise when muscle glycogen stores (termed glucosyl units or GUs) dip below roughly 70 mmol/kg^{1, 2}. Now, average resting muscle glycogen stores in active individuals typically range from 100 to as high as 130 mmol/kg in elite athletes^{1, 2}. But if you're sprint training-particularly while following a reduced carbohydrate diet, the sub-70 mmol/kg level can be reached and depleted quickly.

And it's here, with this readily available 2-pronged anaerobic training punch, that we can really get lipolysis and FFA-oxidation soaring. This is achieved by getting both anaerobic energy-metabolism adaptation and widespread glycogen depletion in tandem.

Research & Precision

There's our window. Now let's try to exploit it with some research and precision. Studies have looked at glycolysis rates in human skeletal muscle in response to moderate to high intensity sprint exercise (~95% of VO2 Max). Those studies have basically established that the net or average glycogen breakdown in response to a moderate sprint is generally ~ 4.3 mmol/kg per minute of activity, which is roughly equivalent to running a single fast quarter mile (400m)³.

Hockey Study

Another study, this time using a group of hockey players, found that performing ten 60-second speed skating intervals at 120% of VO2 Max resulted in the depletion of almost 60% of glycogen stored in the vastus lateralis portion of the quadriceps, with other leg muscles showing similar rates of depletion⁴.

The researchers who ran the study noted that the hockey players who performed the interval sessions showed levels of glycogen depletion that were highly analogous to levels of depletion seen in the leg muscles of cyclists who performed similar sprint intervals.

Quad Study

Finally, a third study that examined quadriceps glycogen depletion patterns following 30 second maximal effort treadmill sprints found that a single, full-on sprint resulted in an on-average degradation of 24% of vastus lateralis glycogen stores⁵.

Lower-Body Depletion Lifting

Obviously, sprinting hits the legs hardest, which means glycogen stores are going to be taxed disproportionately in the quadriceps, hamstrings and calves in proportion to the degree of upper-body muscle recruitment.

So for athletes looking to deplete glycogen stores below 70 mmol/kg, one option - albeit not a fun one - would be to substitute lower-body depletion lifting for the two above recommended sprint sessions. This would then allow for the athlete to reap the additional metabolic benefits of sprint training in addition to achieving the desired level of lower-body depletion.

Even if depletion isn't your primary goal, as a dieter you should still be actively looking to get glycogen stores below that 70 mmol/kg threshold, as it will augment FFA oxidation levels on a 24-hour basis and amplify the amount of fat you can burn during your lower-intensity aerobic cardio sessions. Few things facilitate the above like sprint training.

Now, couple this with all the adaptive cellular responses elicited by sprint work, and I think it's clear why sprinting is the gold medal standard of fat-loss cardio.

Tremblay et al, in their 1994 study "Impact of exercise intensity on body fatness and skeletal muscle metabolism" noted that 15 weeks of HIIT training resulted in a significantly more pronounced reduction in subcutaneous adiposity compared to the ET ('endurance training') control group despite its lower energy cost⁶.

In fact, "when corrected for the energy cost of training, the decrease in the sum of six subcutaneous skin folds induced by the HIIT program was nin-fold greater than by the ET program"⁶.

However, most dieters (especially those looking to lose weight without the assistance of anabolic and/or anti-catabolic drugs) need to keep in mind that leg training volume must be reduced to accommodate for potential sprint-induced wear-and-tear to the legs.

I think a balanced max for leg volume is two intensive sprint sessions and two bouts of lower-body strength work (with weights heavy and working sets in the 3-6 rep range) per week. Yes, even a lot of you natural trainees could probably get away with more, but I see no need for them to.

Sprint Splits

So with that established, here are a few proposed sprint splits for you can feel free to tweak and test out:

Sprinting With An Emphasis On Nutrient Partitioning

Ah yes, the other side of the coin: the guy looking to pack on quality mass without tacking on a subcutaneous spare tire in the process. Fret not: the puissant partitioning benefits sprint training bestows can be of use to you as well. Feel free to 'verbally Falluja' me all the live-long day because I'm going to say it again: I strongly encourage natural bodybuilders on a mass phase to incorporate HIIT sprinting into their splits.

Last time I checked, being willing to include a few short, strategic sprint-sessions into your weekly training allotment while hypercaloric tends to lead to the development of a leaner, faster, and stronger athlete. Here, just as with cutting, it's all about priorities.

In this instance, we're trying to foster anabolism, which means we don't want an energy deficit. Quite the contrary. We want to pack in calories (and likely, in conjunction, carbohydrates) to provide enough energy to build on growth stimuli while keeping intramuscular glycogen stores relatively full. Yup, the tried-and-true recipe for growth.

Why So Hard On Sprinting?

But then let me ask all you 'natural' lifters out there: when was the last time you bulked and managed to build all of that bulk above the belt? Yeah, exactly-for a good 98% of you, some of that Weight gainer Uber-Zeros also ended up adding some size to your other ass, which is why even you had to suck up a few weeks of eating salads and suffering the ignominy of having to make the walk of shame with a shopping bag full of "new-and-improved HydroxyClenaphrine."

Oh, but f*ck sprinting. I mean, all it does is elevate intramuscular glycogen storage potential, increase insulin-stimulated glucose transport and carb tolerance. It also elevates FFA oxidation levels, partitions a higher percentage of ingested calories toward muscle, and curtails fat gain by downgrading DGAT1 activity and glucose uptake into adipocytes. This allows ATP to be saved for energy repletion rather than be "misallocated" to synthesize new triacylglycerol (TAG) in your adipocytes.

And I mean, what a joke: a few 100-meter repeat sprints with full recovery will only minimize anaerobic glycolysis, burn maybe two or three hundred calories max, and generate the AMPk activation that gets the ball rolling on all of the above, leaving you free the rest of your day off to eat and grow in the good places while your body tells your fat-deposits they're going to "get nothing and like it."

Oh, and lest I forget to mention - unlike our poor cutter, we've got a caloric surplus going on, which means recovery from said sprint-session(s) is(/are) going to end up being heightened in addition to work capacity. Sure, I suppose that AMPk is going to result in a minor reduction in protein synthesis that might slow gains transiently. But I have still yet to see a well articulated argument as to why this isn't an infinitely worthwhile tradeoff.

Convenient Methods To Augment Partitioning

Look, you can scream 'neural fatigue' or 'distended tendon' all you want, but the fact of the matter is this: if you're looking for convenient methods to significantly augment nutrient partitioning you can either:

1. Use draconian nutrient manipulation schemes (oh, wait, I said 'convenient,' didn't I. Whoops ... )
2. Take drugs, or
3. Exercise more.

Let's go with option "C." And nothing gives you the same kind of bang for your buck as sprinting (10-20 minutes). You're training your whole body. You're training your body in ways that are almost impossible to duplicate in the weight room, no matter how much iron you try to hoist. Do I really need to keep saying this?

Bulkers, you want to keep your sprints and sprint volume short. 100-meter maximum in terms of distance; 10 intervals at most per session. Really, you should be doing 6-10 sprints with full recovery two to three times per week, using proper workout nutrition protocol. This is nothing new and this isn't rocket science. If you cater to the above, you should have no problems with recovery, injury or overtraining.

Sprint Splits

A few example splits are as follows:

That's all there really is to it. So let's all really get to it, run our sprints, and start taking our fitness and physique goals to that next level. Race ya' to the finish perhaps?

Part 1 | Part 2

References

1. John Ivy "Muscle glycogen synthesis before and after exercise" Sports Medicine (1991) 11: 6-19.
2. William M. Sherman "Metabolism of sugars and physical performance" Am J Clin Nutr (1995) 62(suppl): 228S-41S.
3. Vollestad NK, Blom PC. Effect of varying exercise intensity on glycogen depletion in human muscle fibres. Acta Physiol Scand. 1985 Nov;125(3):395-405.
4. Green HJ. Glycogen depletion patterns during continuous and intermittent ice skating. Med Sci Sports. 1978 Fall;10(3):183-7.
5. Greenhaff PL, Nevill ME, Soderlund K, Bodin K, Boobis LH, Williams C, Hultman E. The metabolic responses of human type I and II muscle fibres during maximal treadmill sprinting. J Physiol. 1994 Jul 1;478 ( Pt 1):149-55.
6. Tremblay A, Simoneau JA, Bouchard C. Impact of exercise intensity on body fatness and skeletal muscle metabolism. Metabolism. 1994 Jul;43(7):814-8.