Category Archives: High Intensity Interval Training

CrossFit Training: High Intensity Interval Training.

CrossFit Training is much like High Intensity Interval Training (HIT).  High Intensity Interval Training is also called Sprint Interval Training (SIT). These training methods involve short bursts of activity. These are hot research topics, and hopefully the information gained will give us better insight into training for health and CrossFit WOD performance. A recent paper on triathletes found large improvements in endurance after only two weeks. Training consisted of ten six-second sprints. Two times a week. Athletes also continued their normal patterns of activity. A control group did not do sprints. Both groups did a timed 10K run.  And a “time to exhaustion” test on a stationary bicycle.

Young CrossFit Kid does CrossFit with cycling
CrossFit sometimes including cycling. Father and Son CrossFit WOD

High Intensity Interval Training for CrossFit? Two weeks of very short burst sprints show big improvements in time

The group that trained with very brief sprints improved their 10K time by 10%. Time to exhaustion did not change. Most interestingly blood lactate did not accumulate as fast in HIT-trained athletes.   Accumulation of blood lactate is one of the things that make you feel crappy when you workout.  Feeling crappy later than sooner is better.  Usually.  Maybe you will get through a WOD without feeling like your body is screaming at all.

Extremely short high intensity interval training also improves function in other ways.  For example, it also seems to improve insulin sensitivity.

What does High Intensity Interval Training mean for CrossFit.

What does this mean for CrossFit?   CrossFit naturally includes a lot of high intensity interval training.  Including sprints in your WODs may be a very good idea. Especially if you are not a great runner.   If you are doing a 400m or longer run try doing some very short bursts. It might end up improving your WOD time if you do a WOD with running.  Every repetition counts.  And every second saved lets you do another rep.

Jakeman J, Adamson S, & Babraj J (2012). Extremely short duration high-intensity training substantially improves endurance performance in triathletes. Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme, 37 (5), 976-81 PMID: 22857018

Jakeman J, Adamson S, & Babraj J (2012). Extremely short duration high-intensity training substantially improves endurance performance in triathletes. Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme, 37 (5), 976-81 PMID: 22857018

Babraj JA, Vollaard NB, Keast C, Guppy FM, Cottrell G, & Timmons JA (2009). Extremely short duration high intensity interval training substantially improves insulin action in young healthy males. BMC endocrine disorders, 9 PMID: 19175906

Getting Faster with High Intensity Interval Training.

High Intensity Interval Training is also called Sprint Interval Training. These training methods involve short, intense bursts of activity. These are hot research topics at present. A recent paper on trained triathletes found large improvements in endurance following a two weeks of sprint training.

Exercise and Weight: crossfit women manage both
High Intensity Interval Training and CrossFit

The training consisted of ten six-second sprints. Two times a week. The athletes also continued their normal patterns of activity. A control group did not do the sprints. Both groups did a timed 10K run and a “time to exhaustion” test on a stationary bicycle. Two weeks of very short burst sprints shows big improvement. The group that trained with very brief sprints improved their 10K time by 10%. Time to exhaustion did not change.

Most interestingly blood lactate did not accumulate as fast in HIT-trained athletes. Accumulation of blood lactate is one of the things that make you feel crappy when you are pushing yourself. Feeling crappy later than sooner is better. Usually. Maybe you will get through a WOD without feeling like your body is screaming at all.

Extremely short high intensity interval training also improves function in other ways. For example, it also improves insulin sensitivity.  So there may be some long term benefit too.

What does High Intensity Interval Training mean for CrossFit?

What does this mean for CrossFit? CrossFit naturally includes a lot of high intensity interval training. Including sprints in your WODs may be a very good idea. Especially if you are not a great runner. If you are doing a 400m or longer run try doing some very short bursts. It might end up improving your WOD time if you do a WOD with running. Every repetition counts. And every second saved lets you do another rep. Babraj JA, Vollaard NB, Keast C, Guppy FM, Cottrell G, & Timmons JA (2009). Extremely short duration high intensity interval training substantially improves insulin action in young healthy males. BMC endocrine disorders, 9 PMID: 19175906

Sprint Interval Training. High Intensity Interval Training.

Sprint Interval Training is a training strategy where an athlete goes “all out” for short burst of time.

The terms “Sprint Interval Training” (SIT) and “High Intensity Interval Training” (HIT) are both used by researchers.   SIT/HIT can be short sprints, but it can also consist of short “all out” bursts of other exercises. This exercise strategy is more like CrossFit.  And findings on SIT/HIT can probably be well applied to CrossFit.

Research on SIT/HIT will tell us a lot about what CrossFit does to and for us.  Think Fran and consider the thrusters as the brief rests.  We discussed SIT as HIT in an earlier article.  How good is Sprint Interval Training compared to traditional moderate intensity endurance workouts?  Like running?  Or cycling?

Is Sprint Interval Training or High Intensity Interval Training better than running or cycling?

That question has not been answered yet.  Here’s what is known so far:

  • Both types of training improved aerobic capacity.
  • Both improved insulin sensitivity.
  • And both reduced arterial stiffness.
  • Both forms of training reduce blood glucose levels.

Arterial stiffness is a risk factor for cardiovascular disease.  Like stroke.  Or heart attack.  Sprint Interval Training can be done in a shorter time than traditional running or cycling.  And it can be done without having a safe place to cycle.  Or run.  Measurable improvements in blood glucose can show up in 2 weeks of 3x a week workouts.   Note that “measurable” change is not the same as “will prevent diabetes.”  More work will need to be done on that.Training produces other adaptive responses.  Including “vascular remodelling.”

So far both endurance training and HIT or SIT training improve vascularization.  Excercise increases growth and development of vascular tissue.  Like capillaries.  And increases blood flow to muscles.  A lot of questions remain.  What happens when training tapers off?  Do improvements only happen in muscles exercised?  Would a runner have a great network of veins and capillaries in legs alone?  Would an intense all over workout like CrossFit give the best over all vascular health?  We’ll see what comes up.

Cocks M, Shaw CS, Shepherd SO, Fisher JP, Ranasinghe AM, Barker TA, Tipton KD, & Wagenmakers AJ (2013). Sprint interval and endurance training are equally effective in increasing muscle microvascular density and eNOS content in sedentary males. The Journal of physiology, 591 (Pt 3), 641-56 PMID: 22946099

Little JP, Gillen JB, Percival ME, Safdar A, Tarnopolsky MA, Punthakee Z, Jung ME, & Gibala MJ (2011). Low-volume high-intensity interval training reduces hyperglycemia and increases muscle mitochondrial capacity in patients with type 2 diabetes. Journal of applied physiology (Bethesda, Md. : 1985), 111 (6), 1554-60 PMID: 21868679

Cocks M, Shaw CS, Shepherd SO, Fisher JP, Ranasinghe AM, Barker TA, Tipton KD, & Wagenmakers AJ (2013). Sprint interval and endurance training are equally effective in increasing muscle microvascular density and eNOS content in sedentary males. The Journal of physiology, 591 (Pt 3), 641-56 PMID: 22946099

CrossFit Fran workout consists of thrusters and pull-ups.

Crossfit High Intensity Interval Workouts

Crossfit – High Intensity Interval Training workouts.

crossfit men discuss womens resistence training
Two ugly crossfit men talk about crossfit, high intensity interval training workouts and WODMASTERS WORKOUT SHIRTS.  Why aren’t they weraing them now?  Get to the shop guys.

Endurance exercise is recommended for cardiovascular health.  Years of research have found that about 30 minutes of cardio will reduce risk of stroke and heart attack.  It will also improve insulin sensitivity, reduce risk of diabetes and improve memory and brain function.  Until very recently, there has been little research on the benefits of CrossFit type exercise on health.  These studies focus on High Intensity Interval Training.  High Intensity Interval Training workouts consist of multiple sets of intense exercise that last 1-4 minutes.  These are spaced with short rest periods.  Or periods of light exercise.

High Intensity Interval Training Workouts with gas mark.
There are so many ways to make life harder. High Intensity Interval Training Workouts can make you hurt faster

Research on this approach to exercise indicates that this approach may number of ways.  These include cardio and respiratory fitness.  And also insulin sensitivity and arterial stiffness.  Arterial stiffness is an indicator for risk of cardiovascular disease.  It is also looking like High Intensity Interval Training may be better at controlling or preventing high blood pressure than the traditional 30 minutes of sustained cardio.

CrossFit Training vs. Running?

The question of is CrossFit better than running is not known yet.  And CrossFit is different than the types of High Intensity Interval Training being tested.  In a nutshell, CrossFit is a fitness program that involves high intensity exercise.  Many different muscle groups are targeted in a CrossFit workout (also known as a CrossFit WOD.)  Workouts may last 5-20 minutes and involve springs, weight lifting, pull-ups and other bodyweight exercises.  If you are wondering “what is CrossFit” try this link. CrossFit exercises may or may not include periods of rest between sets.  However, there is a lot of shifting of focus.  Intensity may be sustained, but not sustained on the same muscle groups.  This might be better for vascular health.

CrossFit High Intensity Interval Training.

crossfit shirt rhino crossfit masters
Stiff, Inflexible, Invincible WODMasters shirt for the Masters CrossFit Athlete. And for other people who may also be stiff and inflexible.

Short periods of high intensity interval training type exercise improve capillary growth.  This allows for greater blood flow to tissues.  Including muscle.   It is possible that intense exercise impacting multiple muscle groups would be better than exercise that impacts only legs (as in running). This is an exciting area of research.  It will be interesting to see what comes up next.  Hopefully more research will be done soon that will look at whether or not CrossFit or High Intensity Interval Training does as well with brain health and control of diabetes.  For a look at recent papers take a look at:

Cocks, M., Shaw, C., Shepherd, S., Fisher, J., Ranasinghe, A., Barker, T., Tipton, K., & Wagenmakers, A. (2012). Sprint interval and endurance training are equally effective in increasing muscle microvascular density and eNOS content in sedentary males The Journal of Physiology, 591 (3), 641-656 DOI: 10.1113/jphysiol.2012.239566

Spence AL, Carter HH, Naylor LH, & Green D (2013). A prospective randomised longitudinal study involving 6-months of endurance or resistance exercise on conduit artery adaptation in humans. The Journal of physiology PMID: 23247114