Adaptations to sprint exercise

Question 1

What variables could you adjust in an interval exercise session that would impact adaptation?

Answer 1

> intensity
> duration (reps, rest)
> modality
> number of reps
> frequency

Question 2

What HR/VO2 max values define ‘HIIT’ training?

Answer 2

> 85% VO2 max or HR max during the intervals.

Question 3

Which metabolic pathways provide the majority
of energy for ATP resynthesis during repeated
sprints?

Answer 3

PCr and oxidative metabolism

Question 4

Can HIIT provide superior aerobic adaptations to steady state exercise?

Answer 4

Yas,
when overall exercise dose is matched, there’s good evidence that superior physiological adaptations can be achieved with HIIT
- (Gibala, 2015)

Question 5

Outline the findings of the MacInnis et al (2017) study that compared 30 mins cycling at 50% Wmax vs. 4 x 5 mins at 65% Wmax.

Answer 5

HIIT trained leg saw greater improvements in citrate synthase (mitochondrial enzyme) than the moderate intensity continuous training (MICT) leg.

Question 6

Are the positive effects of HIIT over MICT seen in unhealthy populations as well as healthy ones?
Provide evidence

Answer 6

Yas,

Weston et al (2014) showed in a meta-analysis, that HIIT was superior to MICT in improving the cardiorespiratory fitness (VO2 max) of individuals with chronic cardiometabolic lifestyle diseases.

Karstoft et al (2015) showed interval walking to improve cardiometabolic health markers to greater extent than continuous waking in type 2 diabetics.

over the course of 12 weeks, HIIT improved VO2 max by 46% vs. 14% increase for MICT in heart failure patients.
A difference of approximately 1 MET.
greater improvements in endothelial function also observed.
- (Wisloff et al, 2007)

Question 7

How much better is HIIT for improving VO2 max than MICT?

Answer 7

over the course of 12 weeks, HIIT improved VO2 max by 46% vs. 14% increase for MICT in heart failure patients.
A difference of approximately 1 MET.
- (Wisloff et al, 2007)

Question 8

What effect does a 1 MET increase in VO2 max have on risk of all-cause mortality?

Answer 8

reduces risk of all-cause mortality by 19%

Question 9

Is HIIT safe?

Answer 9

results are not conclusive.

studies tend to screen out the most at risk individuals.

Question 10

What is Sprint Interval Training (SIT)?

Answer 10

interval training with supramaxaimal / all out efforts.

Question 11

What are some of the benefits of SIT?

Answer 11

> similar (or superior) physiological adaptations to traditional aerobic exercise
dramatically lower volume
far less time commitment

• (Gibala, 2015)

Question 12

Summarise the findings of Burgomaster et al (2005)

Answer 12

found that 2 weeks of SIT dramatically improved active, healthy, young males’ cycle endurance capacity over a control group.
Activity of citrate synthase also was significantly improved.

X should have compared to another condition (e.g. MICT)

Question 13

How many sprints should be performed in a SIT protocol?

Answer 13

just 2 sprints (20 s) in a ten minute period can increase VO2 max by 10-14% over 6 weeks. fewer sprints also reduces total session RPE.
- (Metcalfe et al, 2012)

as sprint number increases past 2, there’s a trend towards lower values of VO2 max change.
- (Songsorn et al, 2016)

Question 14

How long should the SIT intervals be?

Answer 14

20-30 s is optimal.
under 20 s = too low volume
over 30 s = reduced intensity

Question 15

What physiological measures related to performance does SIT improve?

Answer 15

> greater contribution of fat to energy demands during sub max exercise
sparing of muscle glycogen in sub max exercise

• (Burgomaster et al, 2008)

Question 16

What effect does SIT have on pyruvate production during sub-maximal exercise?

Answer 16

less pyruvate produced
more of the pyruvate that is produced enters oxidative metabolism in the mitochondria.
- (Burgomaster et al, 2006)

Question 17

What is the result of less pyruvate production on the muscle environment?

Answer 17

less lactate and H ion accumulation in muscle and better regulation of muscle pH.

Question 18

Would SIT training have an influence on the performance of already trained runners?

Answer 18

Bangsbo et al (2009) found that substituting one high volume running day for a SIT session over 10 weeks improved the 3km and 10km performance of trained, healthy runners.

Question 19

So SIT improves performance… well i’m not Usain Bolt, I just want to get some lean ass arteries.
What can you tell me doc?

Answer 19

just 2 weeks (15 mins) of SIT training dramatically increases glucose tolersance and improves insulin response.

i. e. improved insulin sensitivity.
- (Babraj et al, 2009)

Question 20

So HIIT improves aerobic performance… well I am Usain Bolt, I want to get some lean ass 100m times.
What can you tell me doc?

Answer 20

A HIIT protocol over 5 weeks can improve mean power output in young men during repeat sprints
- (Ortenblad et al, 2000)

HIIT training improves ATP maintenance post-sprint.
- (Barnett et al, 2004)