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.

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