ACWR
Acute:Chronic Workload Ratio = ATL/CTL. Injury risk indicator. <0.8 = detraining; 0.8–1.3 = optimal; 1.3–1.5 = alert; >1.5 = high risk.
Training metrics glossary
Every term you see in Vetta (and most training apps) explained in plain language. Each one in 1-2 sentences.
ATL
Acute Training Load: 7-day TSS average. Reflects recent fatigue.
CSS
Critical Swim Speed. The pace (s/100m) you can sustain for one hour swimming. Defines S1-S5 zones.
CTL
Chronic Training Load: exponential 42-day average of TSS. Reflects your aerobic fitness base.
EF
Efficiency Factor: ratio of normalized power (or pace) to average HR. Goes up as you get fitter (more output for the same cardiovascular cost). Tracks aerobic fitness without testing.
EPOC
Excess Post-exercise Oxygen Consumption: the 'afterburn' after intense training. You burn more calories 12-48h after vs normal rest. Higher with hard intervals than LSD.
FI
Fatigue Index: how much your output drops between the first and last rep of a set. <5% = well-recovered; >15% = fatigued, drop the volume.
FTP
Functional Threshold Power. The wattage you can sustain for one hour on the bike. Defines Coggan P1-P7 zones.
GAP
Grade Adjusted Pace. Pace adjusted for elevation gain/loss. Key in trail to train by real intensity, not raw watch pace.
HRV
HRV (heart rate variability): the variation in time between heartbeats. High HRV = parasympathetic (recovered) nervous system. Low HRV = sympathetic (stressed or fatigued). Better readiness predictor than resting HR alone.
LT
Lactate Threshold: the point where lactate accumulates faster than it clears. ~85-90% of max HR in trained athletes. Defines threshold zones (Z3/Z4).
MAF
MAF (Maximum Aerobic Function): Phil Maffetone's method defining max aerobic HR as 180 - age +/- a health/training adjustment. Useful for pure aerobic base training when lactate testing isn't available.
PP
Peak Power: best wattage sustained over a window (5s, 1min, 5min, 20min, etc.). Defines your power curve — the basis of cycling zones.
RMR
Resting Metabolic Rate: calories your body burns at complete rest, maintaining vitals only. 70kg athlete: ~1500-1800 kcal/day baseline. Higher with more muscle.
RPE
Rate of Perceived Exertion: 1-10 scale of how hard the workout felt. Useful when you don't have GPS/HR.
TSB
Training Stress Balance = CTL − ATL. Today's form. +5 to +20 = race-ready; -10 to +5 = productive; < -20 = overreached.
TSS
Training Stress Score. A load measure combining duration and intensity. 100 TSS = 1 hour at threshold (FTP/CSS). Add weekly TSS → weekly load.
VDOT
Jack Daniels' VDOT: estimates your VO2max from your best recent race time. Vetta uses the median of the top-3 of the last 28 days.
Z2
Zone 2: low aerobic intensity (60-70% max HR or 65-80% Karvonen). The 'volume' zone — where aerobic base is built. Conversational, you can hold sentences.
capilarizacion
Capillarization: increase in capillary count per muscle fiber. Key adaptation from sustained Z2 aerobic training. More capillaries = better oxygen and fuel delivery to muscle. Takes 8-12 weeks of aerobic base to develop.
deload
Deload week: every 3-4 loading weeks, a week with -40% volume to allow adaptation. NOT a week off — an easy week.
drift
Cardiovascular drift: how much HR rises during a long steady-pace session. >5% in 1h suggests fatigue, dehydration or heat. Key in aerobic long runs.
fartlek
Fartlek (Swedish for 'speed play'): unstructured pace changes during a session. Useful to vary intensity without the rigidity of timed intervals.
fast_twitch
Fast-twitch fibers (type II): explosive muscle fibers, high power, low endurance. Subtypes IIa (intermediate, semi-oxidative) and IIx (pure anaerobic). Sprinters/throwers have more type II. Endurance distances use mostly type I (slow) + IIa.
lactato
Lactate: byproduct of glycolytic metabolism. NOT the villain causing fatigue — it's usable fuel for the heart and other muscles. The "lactate threshold" (LT) is the intensity above which the body can't clear lactate as fast as it's produced.
macrociclo
Macrocycle: full training cycle, typically 12-24 weeks toward an A-race. Made of mesocycles.
mesociclo
Mesocycle: 3-6 week block with a specific focus (base, strength, specific, taper). Your macrocycle is made of 3-5 mesocycles.
microciclo
Microcycle: 7-day block — your training week. Vetta builds microcycles respecting safe ramp and periodization.
mitocondria
Mitochondrion: cellular organelle where ATP is produced aerobically. Long Z2 training increases mitochondrial size, density and efficiency — the biological engine of aerobic performance. More durable and deep adaptation than VO2max.
plasma_volume
Plasma volume: amount of plasma (liquid blood component). Rises 5-15% with aerobic training and heat acclimation. More plasma = better cooling and oxygen transport. The first measurable physical adaptation — in 5-7 days.
ramp
Ramp = how much load goes up week over week. >+10% raises injury risk; Vetta caps at +8%.
ramp_seguro
Safe ramp: maximum weekly load increase the body absorbs without raising injury risk. Banister's rule: +5-10% TSS/week. Vetta caps at +8% automatically.
sleep_debt
Sleep debt: accumulated deficit of sleep vs your real need (7-9h). 1 night of <6h = 1.5 days of poor performance. Doesn't 'catch up' by sleeping more on the weekend.
sliding_filament
Sliding filament theory: Huxley's model (1954) explaining how muscle contracts. Actin and myosin filaments slide past each other consuming ATP. The biophysical basis of muscle performance and why fibers tear with eccentric repetitions.
supercompensacion
Supercompensation: your body doesn't just recover after a session — it adapts to a higher level. The window is 24-72h. Training during that window = progress. Before = overtraining.
taper
Taper: 30-50% volume reduction in the 2-3 weeks before an A-race, keeping intensity. Lets fatigue drop without losing fitness.