CoachingAnswer

WHAT IS LONG SLOW DISTANCE TRAINING IN CYCLING?

By Anthony WalshRoadman CyclingUpdated 10 July 2026

ANSWER

Long slow distance (LSD) training is sustained riding at 55-70% of FTP — or roughly 60-75% of maximum heart rate — for 2-5 hours. It builds mitochondrial density, capillarisation, fat oxidation capacity, and connective tissue resilience. Research from the Norwegian University of Science and Technology shows that well-trained cyclists who maintain 75-80% of total training volume at this intensity improve threshold power and time to exhaustion more than cyclists who do the majority of their training at moderate intensity. LSD is the foundation upon which all other training adaptations are built.

KEY TAKEAWAYS

LSD training at 55-70% FTP builds the aerobic infrastructure — mitochondria, capillaries, fat oxidation — that supports all higher-intensity work.
Training must be properly easy: conversational pace, nasal breathing, no burning in the legs. If in doubt, slow down.
Two to three LSD sessions per week of 2-4 hours is sufficient for most amateurs to build a strong aerobic base over 8-12 weeks.
LSD is not the same as moderate intensity — riding at 75-80% FTP is too hard to build base and too easy to build threshold.

WHO THIS IS FOR

IS THIS YOU?

Cyclists who train mostly at moderate intensity and have plateaued

Your training consists of rides that feel moderately hard but never truly easy or truly hard — and your performance has stopped improving despite consistent hours.

Riders building an aerobic base for the season ahead

You are in your off-season or early base phase and want to understand how to structure your easy riding for maximum long-term benefit.

THE ROADMAN VIEW

Long slow distance has a perception problem. It looks and feels unproductive. You are riding slowly, your average speed is embarrassing, and faster riders pass you with alarming frequency. Every instinct says to push harder. But LSD training works precisely because it targets the aerobic adaptations that only occur at low intensity — mitochondrial biogenesis, capillary growth, improved fat oxidation. These adaptations do not happen at tempo or sweetspot intensity.

The concept Anthony returns to repeatedly on the podcast is the polarised model: 80% of your training properly easy, 20% properly hard, and almost nothing in between. The problem is that most amateurs ride at 72-78% of FTP most of the time — too hard to be LSD, too easy to be threshold. This grey zone feels productive but drives neither the aerobic adaptations of easy riding nor the lactate-clearance adaptations of hard riding. LSD done properly should feel almost embarrassingly easy. If it does not feel easy, you are going too hard.

EXPERT EVIDENCE

WHAT THE EXPERTS SAY

Prof Stephen SeilerExercise physiologist, University of Agder, Norway
The training intensity distribution of successful endurance athletes across all sports consistently shows 75-85% of total training volume at low intensity. This is not accidental — low-intensity training drives specific adaptations in mitochondrial density, capillary growth, and substrate utilisation that cannot be replicated at higher intensities. The athlete who trains 80% easy and 20% hard out-adapts the athlete who trains 100% moderate — this finding has been replicated across running, cycling, rowing, and cross-country skiing.

PRACTICAL APPLICATION

DO THIS WEEK

Define your LSD intensity zone precisely
Calculate 55-70% of your FTP or 60-75% of your maximum heart rate. If your FTP is 250 watts, your LSD range is 137-175 watts. If your maximum heart rate is 180 bpm, your LSD range is 108-135 bpm. Set alerts on your bike computer to beep if you exceed the upper limit. Being precise about this prevents drift into moderate intensity.
Build LSD duration progressively over an 8-week base block
Start with rides of 2 hours and add 15-20 minutes per week. By week 8, your long ride should reach 3.5-4 hours. Every fourth week, reduce duration by 25% for recovery. The progressive increase in duration is the primary training stimulus — intensity stays constant throughout the block.
Use the conversation test as a real-time intensity check
You should be able to speak in full sentences throughout an LSD ride. If you can only manage short phrases or are breathing through your mouth, you are too hard. This sounds simple but is remarkably effective at keeping intensity honest, especially on hills where the temptation to push is strongest.

COMMON MISTAKES

WHAT CYCLISTS GET WRONG

MISTAKERiding LSD sessions too fast because easy feels unproductive.
FIXThe adaptations from LSD are intensity-specific — they only occur below the first ventilatory threshold. Riding 10-15% too hard shifts the training effect away from aerobic base building and toward glycolytic work that does not serve the same purpose. Slow down until it actually feels easy.
MISTAKEReplacing all LSD with sweetspot training to be more time-efficient.
FIXSweetspot training is not a substitute for LSD — it targets different physiological systems. Sweetspot improves lactate dynamics and threshold capacity; LSD improves mitochondrial density and fat oxidation. Both are needed, but attempting to build a season on sweetspot alone produces a narrow fitness that breaks down under the demands of long events.
MISTAKEDoing LSD rides without eating because you want to burn fat.
FIXFasted LSD riding increases fat oxidation acutely but also increases cortisol, suppresses the immune system, and reduces the quality of subsequent training sessions. Fuel your LSD rides normally — the fat oxidation adaptations come from the intensity, not from calorie restriction.

FAQ

FREQUENTLY ASKED QUESTIONS

How slow is slow enough for LSD training?

If you can breathe exclusively through your nose, you are in the right zone. If you need to open your mouth to breathe, you are too hard. On a power meter, stay at or below 70% of FTP. On heart rate, stay at or below 75% of maximum. The perceived effort should be 3-4 out of 10 — properly easy.

Is LSD training necessary if I am time-crunched?

Some LSD is necessary even for time-crunched athletes because the aerobic adaptations it drives are not fully replicated by high-intensity training. If you can only train 6-8 hours per week, allocate 4-5 hours to genuine LSD and 2-3 hours to high-intensity work. One long ride per week of 2.5-3 hours provides meaningful aerobic base stimulus.

Can I do LSD training on a turbo trainer?

Yes, but it requires discipline. The lack of terrain variation and environmental stimulation makes it very easy to drift into moderate intensity. Use erg mode set to your LSD wattage, watch a film, and resist the urge to increase power. A 2-hour turbo LSD session is physiologically equivalent to a 2-hour outdoor ride at the same intensity.