Issue #12: Maintaining Strength & Aerobic Fitness with Minimal Training

✍️ Author’s Note

Welcome to this edition of the Threshold Lab newsletter! I’m Stephen Pelkofer, an aspiring HYROX Elite 15 athlete with a men’s pro personal best of 59:41 and men’s pro doubles best of 51:39.

The goal of this newsletter each week is to pick a training topic related to running or HYROX, do deep research into it, and provide actionable protocols that the reader can take away and apply to their training immediately. Let me read the research, listen to the experts, and then give you the tools to make it work for you.

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👨‍💻 Introduction

Topic: Maintaining Strength & Aerobic Fitness with Minimal Training

Life happens: injuries, travel, work deadlines, family commitments, races. You can’t always keep your perfect training schedule. But how much fitness do you actually lose if you cut back? And what’s the smallest dose of training you can get away with to maintain your hard-earned gains?

A recent study looked at exactly that among recreational athletes: how strength, muscle mass, and aerobic fitness hold up when you go from regular concurrent training (strength + cardio) to either one session per week, one session every two weeks, or no training at all. The findings are encouraging, especially if you’re worried about losing fitness in the off-season or during a busy stretch.

For this research, I focused on this paper: Effect of Different Reduced Training Frequencies after 12 Weeks of Concurrent Resistance and Aerobic Training on Muscle Strength and Morphology

⚡ Fast Finds for the busy reader

• One workout a week = full maintenance → Strength, muscle, and VO₂max held steady for 3 months.
  

• One workout every two weeks = ~90-95% maintenance → Small drops, but still kept most gains.
  

• Zero training = rapid loss → Nearly all progress gone within 12 weeks.

🔬 Deep Dive

Study design:
Researchers recruited 27 healthy women aged 18-26 years with no structured strength or aerobic training in the last 2 years. These weren’t elite athletes, more like the recreationally active population many of us coach or train alongside.

Phase 1: Building the fitness base

• 12 weeks of structured concurrent training

• 2 sessions per week

• Each ~1 hour session included:

  • Lower-body heavy strength work (progressive loading leg press sets up to ~80-85% 1RM)

  • High-intensity aerobic work (bike intervals: 10 × 60 seconds at 100% of maximal aerobic power, 60 sec rest)

This was enough to produce clear gains in:

• Max strength (Leg Press 1-RM): increased ~29%

• Aerobic capacity (VO₂max): increased ~20%

• Quadriceps muscle size: increased ~13%

Phase 2: Maintenance test
After the initial 12 weeks, participants were randomly assigned to one of three groups for another 12 weeks:

1. G7: Same style of workout once per week (n=10)

2. G14: Same workout once every two weeks (n=10)

3. GD: Stopped training completely (n=7)

The key here: intensity and volume within each session stayed the same as the peak of the original program. The only thing that changed was how often they trained.

Phase 3: Full detraining
After the 12-week maintenance phase, everyone stopped training for another 12 weeks to see how long gains lasted without any training stimulus.

What was measured throughout the study:

• Strength: Leg press 1-RM

• Aerobic power: Maximal aerobic power test on a cycle ergometer

• Muscle size: Quadriceps cross-sectional area via ultrasound

Results:

• G7 (weekly): Maintained nearly 100% of strength, muscle size, and VO₂max for the entire 12-week reduced phase.
  

• G14 (every 2 weeks): Small drops in everything (~4-9%) but still kept ~90-95% of initial gains from just 6 sessions in 12 weeks. This group also kept almost 100% of the gains in the first 6 weeks.
  

• GD (no training): Lost nearly all improvements within 12 weeks.
  

• Note: After the full-detraining phase (phase 3), all groups reverted to their original baseline for the metrics measured.

Key takeaway: The minimum effective maintenance dose for strength + aerobic fitness, at least for recreational-level athletes, is surprisingly small if you maintain intensity. Check out the appendix for some cool charts from this paper!

Time for the lab notes ⬇️

🧪 Lab Notes

In every issue of this newsletter, the “Lab Notes” are going to be the protocols that you can apply to your training and routine right away. The goal of this section is to translate the science into actionable steps for the reader, whether you’re a recreational runner/HYROX competitor, or someone pushing the limits of their peak potential.

• Maintaining fitness through a busy schedule or injury

  • If you are injured or have a busy schedule for a period of time, don’t panic about losing all of the fitness gains you have recently made.

  • While you won’t be progressing, your gains will not disappear after a week of rest and they can be maintained with minimal doses of intensity each week.

  • If you are injured and worried about losing aerobic fitness, look for an alternative, low-impact, cardio activity that does not aggravate your injury. If you can do this activity once per week at a moderately intense level, it’s likely that you won’t lose fitness for at least 12 weeks.

• Plan training blocks wisely

  • You don’t need to progress everything all at once (and you likely can’t).

  • Putting something like max strength into maintenance mode while focusing on aerobic power development for a 6 week block is a smart way to plan.

  • ⬆️ This way, you make meaningful progress in an area while preserving the area that you might already excel at.

• HYROX Athletes

  • It can be temping to work on running and the eight different movements all year long – this will probably lead to minimal gains after a certain period of quick adaptations occur.

  • You are better off structuring blocks to work on your weaknesses while maintaining the other things.

  • For example, my 1:1 athletes that are in their “off-season” are focusing on foundational aerobic and strength endurance work, while touching HYROX specific workouts maybe once every 10-14 days.

That’s it for this edition of the Threshold Lab. If you enjoyed this and found it useful, please share it with a friend!

📈 Appendix

Figures from the paper: