Selected Activity Risks after ACL Damage

After an ACL injury, (and perhaps other associated knee damage), there are some activities that may present more risk for further damage. This is the case pre-surgery and after surgery to varying degrees. There are just some things that should be either avoided altogether or handled with a great deal more care. Post surgery, over time through rehab, people often can get to near 100% of where they were both for day-to-day activities and even high intensity sports. But along the way, there’s some things to look out for.

Risks for All Phases Post Injury

Unstable Surfaces

Grass, Sand, Gravel, Uneven Trails

These kinds of surfaces can be deceptive. While they may feel manageable at first, they demand constant micro-adjustments from the knee, especially during turning, pivoting, or quick deceleration. That’s risky business when your ACL is compromised or healing.

Tips:

• Avoid trail running or beach sports until cleared by a physical therapist.
• Stick to flat, predictable surfaces when walking.
• Use trekking poles or a cane if needed early on when walking outside. Note that various types of walking sticks and canes are available. They all need to be the appropriate size and should have the proper tips for the surfaces intended to be traversed.

Surfaces in Motion

Boats, Floating Docks, Escalators, Busses, Trains, Trams

Any surface that moves under your feet increases your reliance on reflexive stabilization, something a healing knee can’t reliably provide.

Risks include:

• Sudden slips from unstable footing.
• Jerky balance corrections that stress the healing structures.
• Falls into or against hard objects.

Tips:

• Use handrails generously.
• Avoid boating or dockside activity during early recovery phases.
• Be cautious even months after surgery; balance may lag behind strength gains.
• Wear stable shoes with good grip.

Flying: DVT Risk

Long-haul flights post-surgery carry a heightened risk of deep vein thrombosis (DVT) due to reduced mobility, post-surgical inflammation, and possibly blood clotting medications.

Strategies:

• Discuss with your doctor at what point it’s ok at all to be flying.
• Discuss with your doctor about aspirin or anticoagulants if flying soon after surgery.
• Wear compression stockings during flights.
• Move your ankles in circles or do seated leg pumps every 15–30 minutes.
• Walk the aisle periodically if cleared to bear weight.
• Stay well hydrated.

Other High-Risk Situations

Descending Stairs or Steep Hills

Downhill movements, whether on stairs or sloped terrain, require strong eccentric control of the quadriceps. Without it, the knee may buckle or place excessive strain on healing ligaments. (“eccentric control” will be explained below.)

Tips:

• Learn how to use whatever mobility aids you have to descent appropritely.
• Hold railings and take one step at a time during early rehab.
• Progress to alternating steps only once cleared by your therapist.

Some notes on descending slopes:

Instructions for stairs usually including leading with the bad leg going down. This allows your stronger leg to stay behind and support your body weight as it lowers you down. Handrails should offer additional support and help reduce knee strain.

However, slopes can be different. You need to discuss with your physiotherapist, but some recommend the following:

• Lead with the good leg on slopes. Slopes (especially uneven or steep ones) don’t have the same controlled, step-by-step mechanics as stairs. They demand more eccentric muscle control* (especially from the quads and hamstrings) and more dynamic balance.
• You generally want to lead with the stronger leg and keep the injured leg slightly behind, especially early in recovery.
• This helps reduce the chance of:
  • Buckling or giving way in the injured leg.
  • Overloading the healing knee on uneven ground.
• You may also adopt a slight zig-zag pattern or side-step if the slope is steep, which reduces joint strain.

Sudden Direction Changes

Quick cuts, pivots, or sidesteps, especially common in sports like soccer, basketball, or tennis, are exactly the kind of movements that originally tear ACLs. But the thing is, you don’t have to be playing sports to be faced with this. When you first start going out after surgery, maybe still in your brace, you may find these motions more common than you’d thought about before. Just at a food market, dodging around other shoppers and carts you may find yourself moving laterally in more jerky manners than you have been. What was never even a thought before might all of a sudden be something to take great care with; at least early on until things stabilize.

Tips:

• Avoid any sport that involves rapid lateral motion or unpredictable changes of direction until late-stage rehab.
• Even after return to sport, continue sport-specific agility training with supervision.
• Early on, consider the day-to-day situations where you might get forced into lateral movements.

Lifting or Carrying Heavy Objects

Carrying heavy items (especially while walking, twisting, or on stairs) changes your center of gravity and increases joint loads. This puts the knee in a compromised position for further damage or strain.

Tips:

• Ask for help lifting and carrying during early recovery.
• Use assistive devices like carts or trolleys.
• Re-engage in strength training only under supervision.

Psychological Risk: Overconfidence

Once swelling subsides and walking improves, many people underestimate how much healing is left to do. Just because it “feels fine” doesn’t mean the graft has fully healed or neuromuscular control is back to normal.

Tips:

• Stick to your rehab plan.
• Let milestones be set by objective progress, not just how you feel.
• Track your gains, but stay humble. Your knee is still catching up.

Some Day-to-Day Little Things

We don’t want to be overly paranoid here. We’re trying to get back to normalcy after injury. These are just things to consider a bit as we do that and with which we may need to take some more purposeful care until we’re all the way stable again.

Household Chores: Vacuuming, mopping, or carrying laundry baskets on stairs or over thresholds. Risk: Shifting loads, awkward pivots, or stepping sideways unexpectedly.

Picking Up Children: Risk: Sudden weight shifts or unexpected child movements while you’re off balance. Note: Even squatting or rising from the floor while holding a child can strain the joint.

Walking a Dog: Risk: Dogs lunge or pull quickly, which can cause jerking forces on the knee. Tip: Use a harness with control and avoid leash-handling on stairs or ice.

Showering or Bathing: Risk: Slippery surfaces, narrow entries, awkward standing balance. Tip: Use grab bars, shower stools, and non-slip mats.

Gardening or Yard Work: Risks: Squatting, kneeling, twisting to reach tools or weeds. Tip: Use a small bench or gardening stool instead of deep squats.

Getting In/Out of Cars: Risk: Twisting while stepping in or out, especially with low seats or tight spaces. Tip: Swivel your whole body first, then bring both legs in/out together.

Video Games / VR Headsets: Risk: Sudden reactive movements or pivots while distracted.

Luggage and Travel: Risk: Lifting bags into cars or overhead bins, navigating airport stairs/escalators. Tip: Use roller bags, avoid lifting above shoulder height during early recovery.

Bottom Line

Recovery from an ACL injury is as much about what you don’t do too soon as it is about what you do in rehab. Avoiding risky activities, understanding your environment, and staying honest about your limitations are key to protecting the knee long enough for it to come back stronger.

* About Eccentric Muscle Control

Eccentric muscle control refers to when a muscle lengthens while contracting to control or resist movement, usually to slow something down or absorb force.

In the context of ACL rehab:

When you’re going down stairs or slopes, your quadriceps (front thigh muscles) contract eccentrically to slow the descent of your body and prevent your knee from collapsing forward.

Example:

• When walking down a hill, your quad doesn’t just relax, it actively resists your knee from bending too fast. It’s working hard while lengthening.
• Same with lowering into a squat; your muscles are lengthening under control to manage the descent.

Why it matters in ACL recovery:

• After injury or surgery, eccentric control is often weakened, which makes it harder to handle downhill or stair descents.
• Rebuilding this control is a key focus in later stages of rehab, especially for athletes or people returning to uneven terrain.

Eccentric muscle contraction
Eccentric Muscle Contraction – Science Direct
Understanding Eccentric Muscle Contractions