McGill Big Three

Yes. If the injury really was caused by something as ordinary as climbing stairs with a 25-pound bag, that often suggests the limiting factor wasn’t the bag itself but that one or more of the muscles that stabilize the spine weren’t able to handle the load in that position. The good news is those muscles respond well to training.

Given your routine of tennis, pickleball, and swimming, I would not jump straight to heavy barbell squats. They can be excellent exercises, but they also place significant compressive load on the spine and aren’t the best first step after a recent back strain.

Instead, I’d build strength in this order:

1. Core stability

   
   

   • Modified plank

   • Side plank

   • Bird dog

   • Dead bug

     
     

     These teach the deep abdominal and spinal stabilizers to protect your back during movement.

2. Glute strength

   • Glute bridges

   • Single-leg bridges

   • Step-ups

     
     

     Strong glutes reduce the workload on the lower back when climbing stairs or getting up from the floor.

3. Hip hinge mechanics

   • Bodyweight Romanian deadlift (learning to bend from the hips)

   • Light kettlebell or dumbbell deadlifts once pain-free

     
     

     This is probably the movement pattern most relevant to lifting bags safely.

4. Leg strength

   • Chair squats

   • Goblet squats with a light dumbbell

   • Split squats

     
     

     These strengthen the legs so they do more of the work instead of the back.

5. Carrying exercises

   • Farmer’s carry

   • Suitcase carry (weight in one hand)

     
     

     Since your injury may have occurred while carrying something, these are among the most functional exercises you can do. They train the exact muscles that stabilize your spine while walking with a load.

For someone your age who is already active in racquet sports, one of the best evidence-based routines is often called the McGill Big Three:

• Bird dog

• Side plank

• Curl-up

These were specifically developed to improve spinal stability while minimizing stress on the back.

What about weighted squats?

Eventually, yes—but I’d think of them as an advanced step.

A progression might look like:

• Bodyweight squat → goblet squat → dumbbell squat → heavier squats if you enjoy strength training and remain pain-free.

Your likely weak link

Because you play so much tennis and pickleball, your legs and cardiovascular fitness are already quite good. The more likely issue is that the muscles responsible for stabilizing the trunk while carrying an uneven load haven’t been trained as specifically. That’s why exercises like carries, bird dogs, and side planks may provide more benefit than simply adding heavier squats.

Once this current strain settles down (usually over a few days to a couple of weeks for a mild muscle strain), it would make sense to spend 10–15 minutes, two or three times per week, on these stability exercises. They complement your tennis, pickleball, and swimming and may reduce the chance of another episode from an everyday activity like carrying a bag upstairs.