Training in Zone 4 to Increase Muscular Endurance

training at zone 4 to increase muscular endurance

Last week I wrote about planning for the Base 3 block of my winter training.

The primary goal of the Base 3 period is to improve my muscular endurance while continuing to develop my aerobic efficiency.

The key to improving my muscular endurance over the next 4 weeks will come from increased time riding at my lactate threshold (or zone 4 / FTP). Let’s take a deeper dive into these zone 4 workouts and why they are so important.

What is muscular endurance and why is it so important?

Muscular endurance refers to our muscles’ ability to sustain repeated contractions against resistance for extended periods of time.

For a competitive cyclist, greater muscular endurance will mean less fatigue at the end of races, allowing for higher power outputs in the critical final stages of a race. 

Think of being able to solo away from the bunch in the last 5 miles of a road race, or resisting fatigue enough in the frantic final laps of a crit to be in a position to contest the sprint.

How I’ll be increasing my muscular endurance

I’m using one of Joe Friel’s methods for training in zone 4 during the Base 3 period, which is to focus on intervals of 6 – 12 minutes in length performed in zone 4 (91 – 105% of FTP). Each rest interval between the work intervals should be no longer than 25% of the work interval duration.

The goal of these workouts is to accumulate a total of 20 to 40 minutes cumulative time in zone 4 across each workout.

I’ve scheduled one of these zone 4 / FTP workouts into each week of my 4 week Base 3 block, with the 20 – 40 minute range allowing for plenty of room to increase the total duration at zone 4 across the Base 3 period.

My own tip for maximising the muscular endurance and aerobic benefits of these sessions is to ride an extended amount of time in zone 2 before starting the intervals. I’ll be aiming 90 minutes – 2.5 hours zone 2 before each interval block.

Below is an outline of the interval blocks of each of the workouts, highlighting how they increase throughout my 4 week Base 3 block.

  • Week 1 – 3 x 8 minute intervals at 91 – 105% of FTP with 2 minute rest in between (50 – 60% of FTP) (Total time in zone 4 = 24 minutes)
  • Week 2 – 3 x 10 minute intervals at 91 – 105% of FTP with 2.5 minute rest in between (50 – 60% of FTP) (Total time in zone 4 = 30 minutes)
  • Week 3 – 4 x 8 minute intervals at 91 – 105% of FTP with 2 minute rest in between (50 – 60% of FTP) (Total time in zone 4 = 32 minutes)
  • Week 4 – 4 x 10 minute intervals at 91 – 105% of FTP with 2.5 minute rest in between (50 – 60% of FTP) (Total time in zone 4 = 40 minutes)
FTP workout
Week 1 – FTP workout (3 hours)
FTP workout
Week 2 – FTP Workout (2.5 hours)
FTP workout
Week 3 – FTP workout (3+ hours)
FTP workout
Week 4 – FTP workout (3.5 hours)

Below is the post workout analysis from my first of these sessions – week 1’s 3 x 8 workout. I rode these intervals on Box Hill, Surrey. Note the total duration of nearly 27 minutes spent in zone 4 and nearly 90 minutes of time at zone 2 before starting the intervals.

Post – workout analysis for 3 x 8 zone 4 workout

Other FTP workouts for increasing muscular endurance

Note: these workouts assume the use of a power meter, although heart rate zones can also be used.

Classic 2 x 20 

The classic FTP workout. Tried and tested for many years by professionals and amateurs alike. 20 minutes will feel like a long time and this workout will train you physically and mentally to work for longer durations right on the limit.

  • After a sufficient warm up, ride for 20 minutes at 91 – 105% of your FTP.
  • Recover for 10 minutes at upper zone 1 / lower zone 2
  • Ride another 20 minutes at 91 – 105% of FTP

3 x 15 alternative

An alternative to the classic 2 x 20 session. 3 x 15 minutes gives you an extra 15 minutes of work time compared to the traditional 2 x 20 session. Also as each work block is 5 minutes shorter in duration, you can perform these at the higher end of your zone 4 range.

  • After sufficient warm up, ride for 15 minutes at 91 – 105% of your FTP. If you can, aim to stay at the upper end of this range. 
  • Recover for 8 minutes in upper zone 1 / lower zone 2
  • Repeat 3 times for a total of ~45 minutes at the upper end of zone 4 which is a significant amount of training load.

Over / Unders

The goal here is to alternate between riding just above, and just below your FTP. This is a great way to build your body’s tolerance to lactate acid.

After sufficient warm up you will perform 2 x 21 minute blocks of work. Each block consists of the following:

  • 2 minutes at 110% of threshold
  • 1 minute at 90% of threshold
  • Repeated 7 times = 21 minutes

Thanks for reading, I hope these inspire you to get out there and train these longer zone 4 intervals to improve your muscular endurance.

Catch you soon

Sam @smhdgs