Metrics

A rolling picture of how fit you are, built from the last six weeks of training. It rises slowly when you train consistently and drops when you rest or get sick. Think of it as your aerobic base. Gains are slow, so a single hard week barely moves it.

How tired your body is from recent training, based on the last seven to ten days. It spikes fast after a hard week and drops quickly when you ease off. High fatigue after a big training block is expected and normal.

The difference between your fitness and your fatigue. Positive form means you are rested and ready to perform. Negative form means you are deep in a training block and carrying some tiredness. Zero is neutral. For a race or a key session, aim for a small positive number. Deep in a build phase it is normal to be negative.

Compares how hard you have trained in the last week versus the last month. A ratio near 1.0 means your recent training matches your normal load, which is the sweet spot. Going well above 1.3 is where injury risk starts to climb. The most common cause of overuse injuries is ramping up too fast, so this number helps you see that before you feel it.

Calculated from your cycling power output, specifically how hard you worked relative to your FTP and for how long. The most precise TLS method for cyclists with a power meter.

The running version, calculated from your pace and how hard that pace was relative to your threshold. A tempo run at a tough pace scores higher than an easy jog of the same length.

Built entirely from your heart rate during the workout. Useful when you do not have a power meter or GPS, and it still captures how hard your body worked. Heat, caffeine, or stress can push heart rate up without you actually working harder, so this number can run a bit high on those days.

Power-based TLS for skiing and rollerskiing. One hour at your threshold pole power equals 100 TLS points.

A TLS score based on how much air you breathed per minute. Requires a breathing sensor. Useful as a backup when other sensors are missing.

The simplest method: your perceived effort on a 1 to 10 scale, multiplied by how many minutes you trained. No sensors required. Surprisingly accurate for tracking overall training stress, especially for gym sessions, strength work, or anything wearables do not capture well.

The highest average power you can hold for about an hour. It is the anchor for all of your power zones, so everything else is measured relative to this number. Retest every 6 to 8 weeks since it changes as you get fitter.

A smarter version of average power that accounts for the fact that surging hard for 30 seconds costs more energy than holding the same average power steadily. A hilly, punchy ride will have a higher SP than a smooth one. If SP is much higher than your average wattage, your effort was very uneven.

How hard this specific workout was relative to your FTP. 1.0 means you essentially rode at threshold the whole time. Most training sessions sit between 0.65 (easy) and 0.85 (solid). Racing might push above 1.0.

How smooth or spiky your power output was. 1.0 is perfectly steady. Above 1.05 means a lot of surges and soft-pedaling. A flat time trial might be 1.01, and a punchy criterium might be 1.10 or higher.

Similar to FTP, and it represents the highest power you can sustain aerobically for a long time. Think of it as a slightly more precise ceiling than FTP, derived from testing efforts at multiple durations.

Your sprint battery, meaning the finite amount of energy available for efforts above CP. Every surge, attack, and hard kick draws it down. It slowly recharges when you back off below CP. Once empty, you crack.

A live chart of how much of that battery you have left during a workout. Starts full, drops during hard efforts, and slowly recovers during easier riding. Hitting zero means you are cooked.

The best average power you have ever held for each duration, like 5 seconds, 1 minute, 5 minutes, 20 minutes, and so on. Your power curve is a fingerprint of your strengths. A good sprinter has a very steep curve, and a good time trialist has a flatter one that stays high out to 60 minutes.

How much speed you get per heartbeat. Higher EF means you are moving faster for the same cardiovascular effort, which is a clear sign of improving fitness. Watch it trend upward over a training season. It naturally drops when you are fatigued or in the heat.

Your FTP equivalent for ski and rollerski. The highest average pole power you can hold for about an hour. It anchors all your Nordic intensity zones.

For pole-power data, SP smooths out the natural pulses of poling, like pushing hard and then gliding, to give a truer picture of how hard you actually worked.

How hard this ski or rollerski session was relative to your pFTP. Same concept as Intensity Factor for cycling.

The pace you could hold for about an hour in a race. Your anchor for running intensity zones, the same way FTP anchors cycling zones. Sessions at or near threshold pace are hard but sustainable.

Your pace converted to what it would feel like on flat ground. When you grind up a steep hill and slow to a crawl, your grade-adjusted pace is actually faster than your clock pace, because you were working hard. When you cruise down a descent, it is slower than your clock pace, because gravity did some of the work. This lets a hilly trail run be fairly compared to a flat road run, and it is what feeds your runTLS score.

The heart rate at which your body shifts from burning mostly fat to producing lactate faster than it can clear it. It is the anchor for your heart rate zones, similar to how FTP anchors power zones.

The highest heart rate your heart can reach. Used as a reference for setting zones if you do not have a threshold heart rate. It does not change much with fitness, and naturally decreases a little with age.

Your heart rate first thing in the morning before getting up. A gradual rise in resting HR over several days is a classic early warning sign of overtraining, illness, or poor recovery. Five to seven beats above your normal baseline is worth taking seriously.

Measures whether your heart rate drifted upward during a long workout even though your pace or power stayed the same. Low decoupling, under around 5%, means your aerobic base held steady. High decoupling means your body was working progressively harder to maintain the same output. Decoupling above 5% on an easy long run or ride usually means you went out too hard, got dehydrated, or your aerobic base needs more work.

The intensity where your breathing first noticeably picks up, which is roughly the top of Zone 2. Staying below VT1 is true easy aerobic training.

The intensity where breathing becomes heavy and sustained conversation stops. Close to lactate threshold. Above VT2 is genuine hard work.

Zone 1: Recovery

Very easy, barely breaking a sweat. Used for active recovery days, warm-ups, and cool-downs. Should feel almost too easy.

Zone 2: Aerobic Base

Comfortable, conversational effort. The workhorse of endurance training, so the bulk of your volume should live here. It builds fat-burning efficiency and your aerobic foundation. Most athletes go too hard in Zone 2. You should genuinely be able to hold a full conversation.

Zone 3: Tempo

Moderate-hard. Breathing is elevated and conversation is possible but requires effort. Efficient but metabolically costly, so use it intentionally, not as a default.

Zone 4: Threshold

Hard, sustainable for 20 to 60 minutes. Right around your lactate threshold. Classic interval sessions target this zone. Very effective, but demands real recovery afterward.

Zone 5: VO2max

Very hard, 3 to 8 minute efforts at your limit. Pushes your maximum oxygen uptake and builds raw aerobic power. You cannot sustain this for long.

Zone 6: Anaerobic / Sprint

All-out efforts lasting seconds to 2 minutes. Builds neuromuscular power and sprint capacity. Recovery requirements are high.

A simple 1 to 10 scale for how hard the workout felt overall. 1 is nearly asleep and 10 is maximum effort. No sensor required, just honest self-reflection right after finishing. Surprisingly accurate, since athletes' perceived effort tracks actual physiological load closely when rated honestly.

How well the session went compared to the plan. Did you hit the targets, stay in the right zones, complete the intervals? A useful flag for both athletes and coaches when something is consistently off.