The muscle-building narrative after age 50 isn’t pretty. According to doomers online, your testosterone levels are falling, your energy levels are in massive decline, and everything seems to throw your back out.

But contrary to popular belief, you can still muscle up. And Bryan Krahn, 53 years old and as strong as he’s ever been, is proof. The trainer still works out four or five days a week and has maintained a muscular 210-pound physique.

That doesn’t mean he trains exactly like he did in his 20s. Instead, over the last three decades, he’s made a series of adjustments, shifting his fitness priorities (much less bench pressing) and experimenting with new gym ideas. All that trial and error helped Krahn develop these four critical post-50 training principles, which will allow you to push your muscle-building limits for decades to come without crushing your body.

Like most guys, Krahn relied on dumbbells and barbells for years. But about a decade ago, those exercises started to hurt his joints. He has since shifted his focus to training that minimises his risk of getting hurt. He is quick to note this isn’t about being overly cautious – avoiding injury is not the same as training scared.

Part of the fix for Krahn involved taking a little bit of time off. The other part: he headed to a section of the gym that guys often forget about: the machine area. Because yes, dumbbells and barbells and kettlebells seem to build more ‘functional’ strength (so the narrative goes). But as you get older, those tools don’t always work as well with your joints.

‘Within four or five months, I have no pain, and I’m strong on these machines,’ Krahn says. ‘Cables are indispensable as you get older.’

Machines allow you to focus on doing movements along very fixed tracks, and that lets you concentrate on generating the maximum amount of force with your muscles. That’s a key mechanic for growth.

‘And if you’re a beginner, generating that force isn’t always easy with free weights,’ says MH Fitness Director Ebenezer Samuel, C.S.C.S. ‘Inserting one machine exercise in your routines near the end can ensure you get a chance to push your limits just a bit.’

Two machines to consider: a cable row machine, which blasts your back, and the leg press machine, which ensures you can challenge hamstrings, glutes, and quads with relatively heavy loads.

A bonus: experimenting with machines just may reignite your passion for the gym, too. Krahn says the machines allow him to enjoy his workouts – much like he did in his 20s.

‘I love going to the gym again,’ he says.

From barbell bench presses to back squats to barbell deadlifts, some lifts in the gym are so popular and widespread, they might feel mandatory. But no – Krahn says you don’t have to commit to any of them.

Krahn learned that when training arms. Yes, he loved skull crushers, a triceps exercise that can be notoriously tough on the elbows. But he swapped in triceps pressdowns and still built the muscle he was chasing. He did the same with his biceps work, swapping out supinated dumbbell biceps curls for hammer curls.

‘As soon as something feels off, let’s try a variation,’ he says.

Exercise physiologist and strength coach Dr. Pat Davidson agrees. Most lifts that guys think are mandatory can easily be replaced.

‘So many people just get emotionally attached to an exercise,’ Davidson says. ‘Don’t marry an exercise.’

Krahn says machines are especially valuable here, too.

‘It’s so difficult to get hurt (on machines),’ he says. ‘You can kind of unleash that side of yourself and really push into failure.’

Major lesson: The moment you feel pain in your joints, consider finding a substitute lift for the exercise that’s caused you pain. Don’t wait.

These days, Krahn thinks about building more than muscle. He also wants to maintain his body’s ability to be powerful. What does it mean to be powerful? Muscles produce force – but they also need the ability to produce that force very quickly, which happens whenever you jump, hop, or begin to run.

And sure, plyometric exercises can train power. But once you’re in your 50s, your body can’t always absorb that pounding. That’s why Krahn loves sled pushes.

He uses the move as a warm-up, especially on upper-body days when he’s focused on a variety of push activities. Pushing a weighted sled is a move that can build glutes, quads, and hamstrings, and light up your core. It also quietly trains something called triple extension, the act of straightening your knee, hip, and ankle joints all at once – which is a key to running and jumping.

The best part of a sled push, Davidson says: you get to build power without much injury risk.

‘Anytime you’re in a forward lean acceleration posture, it’s much safer,’ Davidson says. ‘It’s almost a Smith machine of running.’

Consider doing two to three sets of 30-second sled pushes to start your next workout.

Short on time? If Krahn has only 15 minutes in a day, he’ll walk. It’s a non-negotiable in his life.

‘I get a lot done in that 15 minutes,’ he says. ‘I don’t lift weights every day, but I walk every day.’

There are a lot of reasons to add walking into your daily routine. For Krahn, walking gives him the mental reprieve to step away from his responsibilities and keep his mind refreshed. Walking also keeps your body moving, limiting your sedentary time.

At 50, it’s not always about going hard or pushing your limits. Walking keeps your body moving in a joint-friendly manner, even when you’re fatigued (while sneaking in some light calorie burn, too). Daily walking also helps to lower the risk of heart disease, a concern at any age but especially for older adults.

‘Right now, that’s the number one killer in the US,’ Mario Mejia, PT, DPT, physical therapist at Next Play Physical Therapy & Performance, previously told MH. ‘Heart disease can happen anytime but as we age, physiologically there are differences in the heart, lungs, and bone structure.’