Personal fitness has become a numbers game. Thanks to today’s tech, anyone with a pair of running shoes and a smart device can get the full baseball-card treatment — which is to say, an exhaustive breakdown of their athletic ability in several rows of serious stats. Steps taken. Calories burned. Rises and falls in heartbeat. It’s satisfying to have exercise so thoroughly documented. But making sense of that much data can leave you

feelinThe Apple Watch Series 3 is the first fitness-focused smartwatch that moves beyond displaying endless streams of information to serve up actual solutions. Apple’s updated Workout and Activity apps sync seamlessly from watch to phone to track your fitness goals, measure your progress, and integrate appropriate coaching — telling you what you should be doing, and for how long — into your otherwise aimless data-collection regimen. More impressively, the watch’s new GymKit feature works with the machines you’re already using at the gym (so long as that gym is Equinox and those machines are new LifeFitness models, at least for now). With a swipe of your watch on your treadmill’s sensor, the machine communicates its own data directly to your watch, and your watch transposes its comprehensive records onto the machine’s screens. That means you’re fully informed about your body’s current and ongoing performance — and ready to conq

KNOW YOUR CARDIO MACHINES

The gym is full of choices. Here’s how to dedicate your energy

TREADMILL

Best for: Race training, burning fat

Avoid if: You’re just trying to build muscle

Aim for: 20 to 30 minutes of moderate intensity

STATIONARY BIKE

Best for: The injury-prone, avid cyclists, weight loss

Avoid if: You’re pressed for time

Aim for: Longer workouts of at least 30 to 40 minutes

ROWING

Best for: Endurance training, rest days from weights

Avoid if: You don’t know how to row (take a class to avoid injury)

Aim for: 20 minutes is a solid full-body workout

ELLIPTICAL

Best for: Low-impact, full-body workouts

Avoid if: You don’t like the unnatural movement

Aim for: 150 minutes a week

KNOW YOUR METRICS

A quick primer on wading through the data (if you happen to be a 35-year-old man of average size and fitness level)

HEART RATE

Measures: How intensely you’re working

Which tells you: If you’re over- or underdoing that HIIT workout

Target: 90 to 150 beats per minute for optimal conditioning

CALORIES

Measures: How much energy you’re burning

Which tells you: That you’re tearing through fuel rather than storing fat

Target: 500 calories per gym session for moderate weight loss

STEPS

Measures: How far you’ve walked (duh)

Which tells you: Whether your day includes enough light activity

Target: 10,000 to 15,000 steps per day. And always take the stairs