Fysiqal
Cardio
Cardio

Long Slow Distance (LSD)

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DefinitionA short reference note, not a full lesson.
Definition

Extended-duration, low-to-moderate-intensity continuous training that builds the aerobic "base" — high volume, easy pace, long time on task.

Detail

Long slow distance is a continuous-training method emphasizing duration over intensity: covering a relatively long distance (or long time) at an easy, sustainable pace. The intensity is typically low to low-moderate — roughly the LISS/zone-2 range, comfortably below the lactate threshold — so the session can last from 45 minutes to several hours.

LSD is the classic "base training" tool in endurance sport. Its purpose is to drive the peripheral and central aerobic adaptations that come from large volumes of easy work: increased mitochondrial density and capillarization, improved fat oxidation, greater plasma volume and stroke volume, and improved fatigue resistance (see Cardiac Adaptations to Endurance Training and Steady-State vs. Interval Adaptations). Because it is low intensity, weekly volume can be high without excessive recovery cost, which is why polarized endurance programs spend the large majority of their time here (see Training-Intensity Distribution (Polarized / Threshold / Pyramidal)).

LSD overlaps heavily with LISS (Low-Intensity Steady State) and Zone 2 Training; the term is most associated with running and other distance sports and connotes specifically the long end of easy continuous work.

Key facts

  • Long duration (≈45 min to several hours) at easy, sub-threshold intensity.
  • Primary "base"/volume builder in endurance training.
  • Adaptations: more mitochondria, capillaries, plasma/stroke volume; better fat oxidation and fatigue resistance.
  • Forms the bulk of training time in polarized models (~80% easy).

Connections

Sources

Cited in text — not yet linked
Established endurance-training consensus; intensity-distribution evidence from training-distribution literature (polarized vs. threshold models).

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Atlas Connections

Cardiac Adaptations to Endurance Training
Endurance training enlarges and strengthens the heart's pumping capacity — a bigger stroke volume and higher max cardiac output that lower resting heart rate and raise VO2max.
LISS (Low-Intensity Steady State)
Easy, conversational, continuous cardio held at a low intensity for a longer time — gentle on the body, sustainable, and the easiest aerobic dose for beginners.
MICT (Moderate-Intensity Continuous Training)
Continuous cardio at a moderate intensity — the workhorse method behind the public-health "150–300 minutes a week" target and the standard comparison for HIIT studies.
Running / Jogging (Cardio Modality)
A high-impact, high-intensity modality that easily reaches vigorous effort and builds endurance efficiently — but carries the most overuse-injury risk, so mileage must be progressed carefully.
Steady-State (Continuous) TrainingClosely related
Sustained aerobic exercise held at a constant, submaximal intensity for an extended block of time — the backbone method of cardiorespiratory training.
Steady-State vs. Interval Adaptations
Continuous and interval training overlap a lot, but continuous work excels at building aerobic-base/peripheral adaptations and fatigue resistance, while intervals are more time-efficient for pushing VO2max and high-intensity tolerance.
Training-Intensity Distribution (Polarized / Threshold / Pyramidal)
How a week's training time is split across easy, moderate, and hard zones — the main models being polarized (mostly easy + some very hard), threshold (lots of moderate), and pyramidal (a tapering pyramid from easy to hard).
Zone 2 Training
Steady aerobic work held just below the first lactate threshold (LT1) — an easy, conversational intensity that maximizes mitochondrial and fat-oxidation adaptations per unit of fatigue.
Oxygen (Aerobic) Energy SystemClosely related
The slow-but-unlimited pathway that uses oxygen to burn carbohydrate, fat (and a little protein) for ATP — the primary fuel for endurance and the engine that restores the anaerobic systems.