Cycling, Swimming & Endurance Sports

FTP to Training Zones: An Endurance Sport Workflow

Endurance training is most effective when intensity is structured by physiological zones rather than feel alone. These calculators provide the measurements needed to set accurate zones and track progress over a training season.

Establish Your Cycling FTP

Functional Threshold Power (FTP) is the highest average power you can sustain for 60 minutes. Use the Cycling FTP Estimator to calculate it from a standard 20-minute test or a recent race result. A recreational cyclist typically has an FTP of 150-220 watts; trained club cyclists often sit at 230-300 watts; competitive racers exceed 300 watts. With FTP established, the Cycling Power Zone Calculator divides training into seven zones: Zone 1 (recovery, under 55% FTP) through Zone 7 (neuromuscular power, over 150% FTP). For an FTP of 250 watts, Zone 2 (aerobic base) runs from 138-188W, and Zone 5 (VO2max intervals) runs from 301-325W.

Build Your Aerobic Base with Zone 2

Zone 2 training — easy, conversational effort — builds mitochondrial density and fat oxidation capacity. The Zone 2 Training Calculator shows the exact wattage and heart rate range for your aerobic base work. Most endurance coaches recommend 75-80% of total training volume in Zone 2. The Lactate Threshold Estimator finds the inflection point between aerobic and anaerobic metabolism — the power or heart rate above which training becomes unsustainably hard for long durations.

Monitor Training Readiness

The HRV Training Readiness Calculator uses morning heart rate variability data to assess recovery status. High HRV relative to your baseline suggests the nervous system is recovered and ready for hard training. Low HRV after consecutive hard days signals that the body needs easy work or complete rest to adapt. This daily check prevents the chronic fatigue that derails training blocks.

Swimming: Critical Swim Speed and Training Zones

For swimmers, the equivalent of FTP is Critical Swim Speed (CSS) — the pace you can maintain sustainably for a 1,500m effort. The Swim Pace Calculator converts CSS to 100m splits for any target race distance. From CSS, the Swim Training Zones Calculator builds a five-zone structure similar to cycling zones. Zone 2 swimming at 110-115% of CSS (slightly slower than CSS) builds aerobic base, while Zone 4-5 intervals at 95-100% of CSS build threshold capacity. The Swimming Calorie Calculator estimates energy expenditure by stroke type and duration — butterfly burns approximately 40% more calories per minute than freestyle at the same pace.

Equipment and Bike Setup

The Cycling Gear Calculator maps chainring and cassette combinations to speed at any cadence, helping with gear selection for hilly terrain. For a 50-tooth chainring with an 11-speed 11-34 cassette, the easiest gear at 85 rpm produces about 8.5 mph — appropriate for steep climbs. The Bike Fit Calculator uses inseam, torso length, and reach to recommend frame size and saddle height, reducing injury risk and improving power transfer.