Understanding training load (sRPE)

What it is

Training load is a single number combining the perceived intensity of a session and its duration. It gives you one figure per session, in arbitrary units (AU), comparable from week to week. Unbrokn uses Foster's sRPE method (1998), validated and used across almost every sport.

How it's calculated

The formula is simple: load = RPE (1-10) × duration (minutes). Example: 60 minutes at RPE 7 = 420 AU. A heavy strength session at RPE 9 for 75 minutes = 675 AU. A 30-minute mobility flow at RPE 3 = 90 AU.

The RPE scale is the Borg CR-10 scale, where 1 = very easy and 10 = maximal effort close to failure. The athlete enters RPE and duration at the end of the session via the debrief.

The 12-week chart

From an athlete's profile, Evolution tab, the Training load chart stacks daily AU over 12 weeks. You spot at a glance:

• Spikes: too-quick load ramps.
• Dips: undertraining (holidays, sickness).
• Plateaus: consistency.

Monotony and strain

Foster also defined two derived indicators:

• Monotony = weekly average load / standard deviation. A very uniform week (all sessions identical) yields high monotony. Alert threshold: 1.5. Above 2.0, overtraining risk rises.
• Strain = weekly load × monotony. That's accumulated fatigue. Foster's thresholds: 4500 (caution), 6000 (illness/injury risk).

Unbrokn computes both in the background and triggers an alert when an athlete crosses the thresholds. The athlete shows up in Athletes to watch.

How to use it

• Avoid weekly load increases above 10%.
• Alternate: 3 ramps then 1 deload (-40 to -50%).
• If monotony exceeds 2.0, break the routine: insert an easy session or a different sport.
• Cross load with the wellness score: stable load but falling wellness = warning signal.

Known limits

sRPE depends on the athlete's input quality. If they consistently under- or over-estimate their RPE, the load is biased. Calibrate athletes early: show them the scale, give concrete examples at each level. Expect 3 to 6 months for an athlete to become reliable on RPE.

Source

Foster C. (1998). Monitoring training in athletes with reference to overtraining syndrome. Medicine and Science in Sports and Exercise, 30(7), 1164-1168.