Training Load Calculator
Log your weekly sessions, calculate acute & chronic training load, and prevent overtraining
Training Load Calculator
Log your weekly sessions, calculate acute & chronic training load, and prevent overtraining
What is Training Load and Why Should Runners Track It?
Training load quantifies the total physiological stress of your workouts — combining volume (duration) and intensity (RPE or heart rate zone) into a single number. The concept emerged from sports science research in the 1970s through Bannister's TRIMP (Training Impulse) model. For runners, tracking load week to week is the most evidence-based method for balancing fitness development against injury and overtraining risk.
This calculator uses the Session RPE method, developed by Carl Foster (University of Wisconsin, 2001). Session Load = Duration (minutes) × RPE (Borg CR-10 scale, 1–10). The simplicity is its strength — it captures perceived exertion across all session types (running, strength, cross-training) in a single number. The 7-day sum is your Acute Training Load (ATL, representing fatigue), while a 42-day average gives Chronic Training Load (CTL, representing fitness). The difference — Training Stress Balance (TSB = CTL − ATL) — indicates readiness and form.
Research consistently shows that a weekly load increase of more than 10% significantly raises injury risk, particularly for stress fractures, shin splints, and tendinopathy. The 10% rule, while debated in exact percentage, is supported by epidemiological studies and remains the most widely used training progression guideline. This calculator flags weeks where your ramp rate exceeds safe thresholds and provides recommendations based on your current ATL–CTL balance.
How to Use This Calculator
TSB Interpretation
- • TSB > +15 (Fresh): Well rested — ideal for races or hard workouts
- • TSB −5 to +15 (Optimal): Balanced fatigue/fitness — peak training window
- • TSB −5 to −20 (Fatigued): Accumulated fatigue — reduce volume 20–30%
- • TSB < −20 (Overreached): Overtraining risk — take 3–5 days easy or rest
- • Ramp rate > 10%: High injury risk — slow the progression
Why Tracking Training Load Prevents the Injuries That 'Just Happen'
Most running injuries don't feel sudden to the athlete but actually are — a stress fracture or tendinopathy that appears to come from nowhere is usually the endpoint of weeks of accumulating load that outpaced the body's ability to adapt, not a single bad run. Training load tracking makes that slow accumulation visible before it becomes an injury, which is exactly why professional teams treat it as a mandatory monitoring tool rather than an optional extra.
This is standard practice at elite level — professional running and team-sport programmes combine GPS data with daily RPE ratings specifically to catch dangerous load spikes early, while most recreational runners train entirely by feel and only discover they've overreached once symptoms appear, which is a major reason amateur injury rates run considerably higher than professional rates relative to training volume.
The concept translates across sports differently: a marathon runner's load builds gradually over months toward one peak event, while a cricket or football player's load needs managing around a season's worth of matches, meaning team-sport athletes often need to protect recovery windows around fixture congestion rather than following a single linear progression toward one race day.
?Frequently Asked Questions
This calculator uses the Borg CR-10 scale (0–10) where 1 = very easy/recovery run, 3 = comfortable aerobic effort (can hold conversation), 5–6 = moderate to somewhat hard (tempo), 7–8 = hard (threshold/intervals), and 10 = absolute maximum effort. Rate the overall session — not just the hard part. A 60-minute easy run is typically RPE 3; a 45-minute session with 5×1km at 5K pace might be RPE 7. The key is consistency in how you rate effort over time.
Acute Training Load (ATL) is the 7-day rolling average of your daily training load. It reflects current fatigue. Chronic Training Load (CTL) is the 42-day (6-week) rolling average — your fitness base. The concept was developed by Bannister (1991) and popularised in cycling through TrainingPeaks Performance Management Chart. A high CTL with low ATL means you are fit and fresh (positive TSB). High ATL relative to CTL means you have loaded beyond your current fitness base — classic overreaching.
The 10% rule has mixed evidence. A landmark study by Buist et al. (2010, British Journal of Sports Medicine) found that beginners following a novice programme with gradual progression had 50% fewer injuries than those who progressed faster. However, the 10% figure is somewhat arbitrary — the underlying principle (graded exposure, avoiding abrupt load spikes) is robustly supported. For runners with a large CTL base, 10% increases are conservative; for beginners, even 10% can be too much. What matters most is monitoring the acute:chronic load ratio (ideally between 0.8 and 1.3).
Building a meaningful CTL takes 10–16 weeks of consistent training. Since CTL is a 42-day rolling average, changes are gradual by design. A beginner starting from zero might reach a CTL of 30–50 AU/day after 3–4 months. An experienced marathon runner in full training might have a CTL of 70–100 AU/day. CTL drops rapidly during injury or illness (approximately 10–15% per week of inactivity), which is why returning from a break requires 4–8 weeks of gradual build-up before resuming pre-injury load levels.
Yes — negative TSB is normal during a training block. The body adapts to training stress (supercompensation) during recovery after hard periods. Most successful marathon programmes operate with TSB between −10 and −20 during peak training weeks, then taper for 2–3 weeks to bring TSB to +5 to +15 by race day. The danger zone is TSB below −25 for extended periods without recovery, which leads to overtraining syndrome — a prolonged state of underperformance, fatigue, and mood disturbance that can take weeks or months to resolve.
ACWR (popularised by sports scientist Tim Gabbett) compares your recent 7-day load against your rolling 28-day average load, aiming to keep the ratio between roughly 0.8 and 1.3 — the "sweet spot" associated with lower injury risk in his research. It measures similar territory to TSB (Training Stress Balance) used here, but ACWR is more commonly cited in team-sport sports science literature while TSB and the CTL/ATL framework originated in endurance and cycling training.
Running load is fairly predictable and self-directed — a runner controls their own weekly volume and can plan a smooth progression toward a single race. Team-sport athletes have much less control over match scheduling, and load often spikes unpredictably around fixture congestion (multiple matches in a short window), which is why team-sport load monitoring focuses more heavily on managing recovery windows between matches than on a single linear build toward one event.