Sprint Intervals vs. Endurance Training on your bike?
Updated: Oct 25, 2018
Can you grab the same benefits sprinting on your bike than you can on longer rides?
The purpose of this post is to evaluate the changes in physiological and exercise adaptations after low volume sprint interval training (SIT) and high volume endurance training (ET).
My thesis work has led me to an article that has given me some new insight on this topic.
I think the main question is, can this truly benefit an athlete who is racing at any distance? Can someone who is training for an ironman rely only on short term sprint interval training? Hard for me to believe.
Athletes across the nation are constantly puzzled with what type of training to complete at what time during the year. Some coaches are a HUGE fan of long distance endurance training at a low percentage of your FTP or VO2max. These coaches believe that this training will help you go faster by training slower. Is this true? Well, this blog post should finalize a couple ideas.
So, What were the Methods!?
In a study performed by researchers at McMaster University in Ontario, Canada, 16 subjects were split into two groups. One group performed sprint interval training for 2.5 hours per week, 3 sessions per week for 2 weeks. The other group, labeled the endurance group, exercised 10 hours per week for the 2 weeks. The endurance group exercised at 65% of their VO2peak for 90-120 min while the sprint group performed 4-6 intervals of 30 seconds max effort on a bike with 4 min of recovery.
How were the results measured?
To measure the effects of these different treatments, These subjects went through pre-tests. This involved a 50 kj time trial, a 750 kj time trial, and the sprint group performed a Wingate test while the endurance group performed a sub max bike test. There were also biopsy samples taken of the muscle so the researchers could measure the oxidative capacity of the muscle.
DRUM ROLL PLEASE
There were similar improvements seen in both groups! What is crazy is the sprint group only exercised 2.5 hours per week while the other group spent 10 hours a week! Think of the savings on time! This gave the sprint group more time to spend tackling other aspects of their life. For the nerds out there, the buffering capacity of the muscle, increase in watts, increase in the capacity of glycogen in the muscle increased similarly in both groups!
Now, looking at the statistics in the study and at the actual results, it looks like the sprint group actually did show more improvement across the board in all categories. The 750 kJ cycling test decreased after training by 10.1% and 7.5% in the sprint and endurance groups, respectively. After the training protocol, there was a corresponding increase in mean power output during the 750 kJ time trial from 212 ± 17 to 234 ± 16 W in the sprint group and from 199 ± 13 to 212 ± 12 W in the endurance group Although the amount of improvement was smaller, the time required to complete the 50 kJ test also decreased after training by 4.1% in the sprint group (Post: 113 ± 6 versus Pre: 117 ± 6 s) and 3.5% in the endurance group (Post: 122 ± 10 versus Pre: 115 ± 9 s). Following training, mean power output during the 50 kJ time trial increased from 435 ± 23 to 453 ± 25 W in the sprint group and 416 ± 39 to 433 ± 40 W in the endurance group.
So moving forward with training, If you're looking for a time saving way to see improvements in fitness, go with sprint interval training. However, this does not take the place of endurance training for long distance events! You should not believe that be performing sprints 3 times a week for 6-12 weeks you'll be ready for an ironman! This study did not measure fatigue of the subjects and it only lasted 2 weeks. Imagine if you did these hard sprints for many weeks. What do you think would happen to your body? First, in my opinion, you would stop adapting from the exercise by doing the same training again and again. Second you're asking yourself for injury. This type of training put's the body under much more force that endurance training at 65% of VO2peak.
Training distance is going to teach your muscles and your body so many other positive aspects. Maybe this is leading to another post on those benefits versus the sprint interval benefits. Who has measured this? I'll have to dig into a study that tries to show the opposite or measures different aspects of human physiology.