Training Intensities

Training intensities divide load into three tiers (LIT, MIT, HIT) so that sessions and races can be prescribed and analysed by their objective load.

Definition

Training intensities are a method of dividing load into three tiers: low, medium and high. Unlike the more finely resolved training zones, this three-way split works both for prescribing sessions and for analysing recorded sessions and races.

The names of the three tiers vary across the literature. obseed uses:

LIT – Low Intensity Training
MIT / SII – Medium Intensity Training, or Stress-Inducing Intensity
HIT – High Intensity Training

Zone	Physiological description	Share of threshold	Typical duration	Purpose
LIT	below VT1, purely aerobic, lactate stable near resting level	bike 50–82 % FTP, run 172–115 % of rFTP pace, HR 60–80 % HRmax	1–6 h	base, fat metabolism, volume
MIT / SII	between VT1 and VT2, lactate elevated, sustained muscular stress	bike 82–105 % FTP, run 115–92 % of rFTP pace, HR 80–90 % HRmax	20–90 min continuous	race-specific endurance, threshold
HIT	above VT2, near VO2max, sustainable only briefly	bike > 105 % FTP, run < 92 % of rFTP pace, HR > 90 % HRmax	30 s – 8 min per interval	VO2max, anaerobic capacity

Effort below the LIT boundary (e.g. power under 50 % FTP) is left unclassified and does not enter the intensity distribution.

Why it matters

The three-way split makes the intensity distribution of a week or block visible at a glance. A polarised distribution of roughly 80 percent LIT and 20 percent HIT is considered especially effective for endurance athletes; a high MIT share, by contrast, is a common pattern among athletes who train a lot but stagnate.

The middle tier deserves particular attention. MIT is the intensity at which the body is placed under sustained stress through muscular work, hence the name «stress-inducing intensity». HIT loads the body more, but intervals there rarely last more than a few minutes, so the deliberate overload can usually be recovered from.

How obseed measures it

obseed classifies every segment of a recording automatically once performance benchmarks are stored. The control metric depends on the data available.

Without specific benchmarks: heart rate (HRmax)

Unclassified: < 60 % HRmax
LIT: 60–80 % HRmax
MIT: 80–90 % HRmax
HIT: > 90 % HRmax

Swimming: Critical Swim Speed (CSS)

Unclassified: pace slower than 122 % of CSS
LIT: 122–102 % of CSS
MIT: 102–92 % of CSS
HIT: faster than 92 % of CSS

Running: functional running pace (rFTP)

Unclassified: pace slower than 172 % of rFTP
LIT: 172–115 % of rFTP
MIT: 115–92 % of rFTP
HIT: faster than 92 % of rFTP

Running additionally checks cadence: a segment only counts as running from 140 steps per minute upwards; below that it remains unclassified.

Cycling: Functional Threshold Power (FTP)

Unclassified: < 50 % FTP
LIT: 50–82 % FTP
MIT: 82–105 % FTP
HIT: > 105 % FTP

Pace values are time per distance (min/km, min/100 m). A numerically smaller value therefore means a higher speed, which is why the percentages look mirrored at first glance: 10:00 min/km equals 6 km/h, 4:00 min/km equals 15 km/h.

With metabolic testing: ventilatory thresholds

If a spiroergometry is available, obseed replaces the percentage boundaries with the measured thresholds. LIT then extends up to VT1, MIT from VT1 to VT2, and HIT begins above VT2; the lower cut-off stays at 50 % of VT2 power or 172 % of VT2 pace.

This is the method obseed prefers, because only measured thresholds reflect actual energy supply. Percentages of an estimated FTP are an average across many athletes and can be a whole intensity tier off for the individual.

Example

A runner with an rFTP of 4:30 min/km completes a 60-minute run. From the rFTP the boundaries follow: LIT from 7:44 to 5:10 min/km, MIT from 5:10 to 4:08 min/km, HIT faster than 4:08 min/km.

LIT upper limit: 4:30 × 1.15 = 5:10 min/km
MIT upper limit: 4:30 × 0.92 = 4:08 min/km

The recording shows 42 minutes at 5:25 min/km, 15 minutes at 4:45 min/km and 3 minutes at 3:55 min/km. obseed logs 70 percent LIT, 25 percent MIT and 5 percent HIT. The planned «easy run» thus spent a quarter of its time in the stress-inducing tier, a typical pattern that leads to silent overload over the weeks.

References

Seiler, S. (2010): What is best practice for training intensity and duration distribution in endurance athletes? International Journal of Sports Physiology and Performance.