Impact exercises are often touted as one of the best ways to build stronger bones, but they’re not suitable—or safe—for everyone.
Dr. Lisa, a physical therapist specializing in osteoporosis and bone health, recently shared her approach to modifying impact exercises so clients can still benefit from ground reaction forces without unnecessary risk.
Her strategies offer a smarter, more personalized path to bone health that doesn’t require risky jumps or movements that might cause injury.
Whether someone is dealing with osteoporosis, arthritis, balance issues, or simply doesn’t feel comfortable with high-impact movements, these modifications provide powerful alternatives.
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Why Impact Matters for Bone Health
Impact exercises work by creating ground reaction forces—multiples of body weight that compress the skeleton in beneficial ways. When the body pushes into the ground, the ground pushes back, creating compression that signals bone cells to strengthen and lay down more bone tissue.
Dr. Lisa explains that good stress from compression tells bone cells they need to be more robust. The goal is achieving between two and four times body weight or more to provide adequate stimulus for bone growth.
That good stress that tells our bone cells, hey, I need to be more robust and lay down more bone.
But traditional high-impact exercises like jumping aren’t appropriate for everyone, especially those with existing fractures, spinal conditions, or joint problems.
The Essential Foundation: Strength Before Impact
Before anyone begins impact training, Dr. Lisa emphasizes establishing a baseline of strength, including foot strength. This foundation is critical for tolerating impact activities safely.
You need strength exercise first before you start impact.
Without adequate strength, the risk of injury increases significantly. Building this base protects joints, improves stability, and prepares the body for progressively greater forces.
Strategy One: Harness Power Training
For clients who aren’t ready for traditional impact exercises, Dr. Lisa turns to power training—using strength combined with speed to manipulate and increase ground reaction forces.
From Slow Squats to Explosive Movement
A standard bodyweight squat performed at normal tempo generates approximately one times body weight. But changing the tempo dramatically alters the equation.
By performing squats explosively—pressing the floor away with speed—ground reaction forces can reach two or more times body weight. This delivers meaningful bone stimulus without leaving the ground.
Adding external weight further increases these forces, creating even greater compression on bones.
- Slow bodyweight squat: 1x body weight
- Explosive bodyweight squat: 2+ times body weight
- Weighted explosive squat: Even greater forces
Strategy Two: Progressive Step Training
Step exercises offer another excellent modification that generates substantial ground reaction forces while remaining accessible.
The Height and Direction Variables
Dr. Lisa uses steps of varying heights and approaches them from different directions to control intensity:
With a 15 cm (6-inch) step:
- Lateral step-up: 2.1 times body weight
- Forward step-up: 2.2 times body weight
Increasing to a 30 cm (12-inch) step:
- Forward step-up: 2.7 times body weight
- Lateral step-up: 3.1 times body weight
Simply raising step height significantly increases ground reaction forces. Lateral stepovers are particularly effective for combining power and speed advantages.
Adding Weight for Greater Impact
For clients who cannot or don’t want to jump but still want impact-like benefits, adding weight to step exercises is transformative. This allows someone to achieve higher ground reaction forces without leaving the ground.
For people who cannot jump, it’s not safe. They don’t want to jump, but they want the benefit of getting more force on their bones like impact. That’s a great way to do it.
Strategy Three: Strategic Stomping
While impact exercises generally benefit the femoral neck and hip more than the lumbar spine, stomping offers a targeted approach that’s gentler on sensitive areas.
Dr. Lisa prefers stomps over heel stomps because they’re typically less irritating to both the back and pelvic floor. A proper stomp can deliver an impressive 4.6 times body weight to the femurs.
How to Incorporate Stomps
Dr. Lisa recommends adding stomps during regular walks:
- Perform 8 to 10 stomps at intervals throughout your walk
- Aim for a total of 40 stomps per session
- Complete 3 to 4 sessions per week
This simple addition transforms an ordinary walk into a successful impact training session without requiring any special equipment or high-risk movements.
The Progressive Approach to Bone Loading
What makes Dr. Lisa’s approach particularly effective is her emphasis on gradual progression. She systematically moves clients up the scale from one times body weight toward the optimal range of two to four times body weight or more.
This progression respects individual limitations while still challenging bones sufficiently to trigger adaptation. It acknowledges that different factors—from osteoporosis severity to spinal conditions, balance issues, arthritis, and joint stability—require personalized modifications.
Finding What Works for Your Body
The beauty of these modifications is they provide options rather than obstacles. Someone doesn’t need to perform “crazy jumps” or movements that feel unsafe to achieve bone-building benefits.
By understanding how ground reaction forces work and strategically manipulating variables like speed, weight, step height, and movement direction, it’s possible to create customized bone-loading programs that feel good while delivering results.
You can still find ways to use ground reaction forces to get more good compression on your skeleton to help your bone cells tell them they want to be stronger for you.
Whether starting with explosive squats, progressing through step variations, or adding stomps to daily walks, these evidence-based modifications make bone health accessible to more people. The key is finding the right intensity and method that balances safety with adequate stimulus—and that formula will look different for everyone.
