Is Jumping Really Bad for Your Knees? What Research Reveals About Cartilage, Bone Strength, and Muscular Strength
For many women, a diagnosis of knee osteoarthritis leads to a familiar recommendation: be careful with impact.
Running, jumping, hopping, and other higher-impact activities may seem like exactly the types of exercise someone with an arthritic knee should avoid. At the same time, impact exercise can provide an important stimulus for maintaining bone strength after menopause (especially at the neck of the femur).
That creates an important question and the topic of this article.
Can postmenopausal women with knee osteoarthritis perform impact exercise without damaging their knees?
A 2017 randomized controlled trial by Multanen and colleagues provides useful insight. The researchers followed postmenopausal women with mild knee osteoarthritis for an entire year while one group performed progressively more challenging high-impact exercise. They measured not only bone outcomes, but also the biochemical composition of knee cartilage using MRI.
Who Participated in the Study?
The researchers initially recruited women from the Jyväskylä region of Finland through newspaper advertisements.
A total of 298 postmenopausal women expressed interest. After telephone interviews, clinical examinations, knee and lumbar-spine X-rays, and DXA testing, only 80 women met all of the study requirements and were randomized.
To participate, the women had to:
- Be postmenopausal
- Be between 50 and 65 years old
- Experience knee pain on most days
- Have radiographic evidence of mild tibiofemoral knee osteoarthritis, classified as Kellgren-Lawrence grade 1 or 2
- Perform no more than two sessions of intensive exercise per week at baseline
- Be medically capable of participating in the exercise program
Women were excluded for several reasons, including osteoporosis, BMI greater than 35 kg/m², previous knee surgery, knee instability, inflammatory joint disease, recent intra-articular steroid injections, or contraindications to MRI or the contrast agent used for cartilage imaging.
The osteoporosis exclusion is especially important.
Women with a proximal-femur T-score below −2.5 were excluded. Of the final screening group, two women were specifically excluded because their proximal-femur T-score was below this threshold.
So although this study has implications for bone-health programming, it was not a study of women with established osteoporosis.
At baseline, the exercise group had an average age of about 58 years and an average BMI of 27.1 kg/m². Approximately 68% of participants had Kellgren-Lawrence grade 2 OA and 32% had grade 1. The control group had a very similar distribution.
How Was the Study Designed?
The 80 women were randomly assigned to one of two groups:
- 40 women to the high-impact exercise group
- 40 women to the control group
Randomization was computer generated and stratified by osteoarthritis severity so that Kellgren-Lawrence grades 1 and 2 were appropriately represented in both groups.
Two women assigned to exercise withdrew immediately after randomization and another two were lost during follow-up. Ultimately, 36 women in the exercise group and all 40 women in the control group completed the 12-month assessment.
The control group was asked to continue its normal leisure-time activity. To help maintain participation in the study, the researchers offered control participants social meetings approximately every three months that included lectures on topics such as healthy lifestyle and relaxation.
Most outcome assessors were blinded to which group participants belonged to, reducing the risk that knowledge of group assignment would influence the measurements.
What Did the Exercise Program Actually Involve?
The exercise intervention lasted 12 months.
Participants were prescribed:
3 supervised sessions per week, approximately 55 minutes each.
The sessions consisted primarily of high-impact aerobic and step-aerobic exercise performed to music. Training included:
- Stepping
- Jumping
- Rapid changes of direction
- Higher-impact aerobic movements
- Progressive jumping over obstacles
Knee movement during the sessions ranged from approximately 5 degrees of flexion (near full extension) to about 70 degrees of flexion.
One of the most important details of the study is that the exercise was progressive.
The loading was increased approximately every three months. Progression included increasing both the height of the step and the height of obstacles participants were asked to jump over.
The women therefore did not begin the study immediately performing the most demanding jumps.
They were progressively exposed to greater impact over the course of a full year.
All sessions were supervised by instructors who had been specifically trained to deliver the program.
How Much Training Did They Actually Do?
Although three sessions per week were prescribed, average attendance was 68%.
That worked out to approximately:
2.1 exercise sessions per week on average.
This is useful when interpreting the results because the improvements occurred even though participants did not complete every scheduled session.
How High Was the Impact?
The researchers did something particularly valuable: they actually measured impact exposure rather than simply labeling the program “high impact.”
Participants wore accelerometer-based movement monitors during selected exercise sessions. Exercise impacts were divided into five acceleration ranges:
| Acceleration | Example activity |
| 0.3–1.0 g | Walking |
| 1.1–2.4 g | Stepping |
| 2.5–3.8 g | Jogging |
| 3.9–5.3 g | Running and jumping |
| 5.4–9.3 g | Jumping and drop-jumping |
Across the measured exercise program, participants accumulated substantially more impact loading than controls. The researchers also measured normal daily physical activity outside of training and found no meaningful difference between groups, supporting the conclusion that the difference in loading was primarily produced by the exercise intervention itself.
One caution is important here: these numbers represent accelerometer-measured acceleration, not direct ground-reaction forces expressed as multiples of bodyweight. They should not be interpreted as saying the knee experienced nine times bodyweight during a jump.
How Did the Researchers Measure Bone Strength?
Rather than looking only at standard bone mineral density, the investigators used DXA-based advanced hip analysis to estimate the geometry and structural strength of the femoral neck.
They measured:
- Cross-sectional area
- Femoral-neck width
- Section modulus, which is an estimate of the bone’s resistance to bending
This matters because fracture resistance depends on more than the amount of mineral present in the bone. Bone geometry and the distribution of that mineral also influence structural strength.
What Happened to Femoral-Neck Strength?
After 12 months, the exercise group had significantly better femoral-neck bending strength than the control group.
The between-group difference was approximately 4.4%, and after adjusting for age, height, body mass, and baseline values, the treatment effect remained approximately 4.0%.
The DXA-derived section modulus increased from an average of about 640 to 658 mm³ in the exercise group, while the control group declined from approximately 609 to 600 mm³. The adjusted difference between groups was statistically significant.
The researchers also found that greater total physical-activity loading was associated with greater improvements in femoral-neck bending strength.
The relationship was modest but statistically significant:
r = 0.29, p = 0.012.
Interestingly, the study did not find significant between-group differences in femoral-neck cross-sectional area or external width. The authors suggested that the improvement in estimated bending strength could potentially reflect changes in bone geometry or the distribution of mineral within the femoral neck, although the study did not use CT imaging capable of directly confirming this explanation.
What Happened to the Knee Cartilage?
This was perhaps the most clinically interesting part of the study.
Researchers examined the biochemical composition of cartilage using two quantitative MRI techniques:
T2 mapping provides information related to the collagen network and water content of cartilage.
dGEMRIC (delayed gadolinium-enhanced MRI of cartilage) provides information related to glycosaminoglycan content, an important component of cartilage structure.
The researchers focused on the weight-bearing cartilage of the medial and lateral femoral condyles…the areas most exposed to loading during the exercise program.
After 12 months, there were no statistically significant detrimental differences between the exercise and control groups in either T2 or dGEMRIC measurements.
In other words, a year of progressively increased high-impact exercise did not produce measurable deterioration in the biochemical composition of the load-bearing knee cartilage in these women.
What About Pain and Function?
The researchers also tracked clinically relevant osteoarthritis symptoms using the WOMAC questionnaire.
At the end of the study, there were no significant differences between groups in knee pain, stiffness, or physical function.
A related publication using this same study population also found improvements in several measures of physical performance, including approximately 11% greater knee-extension strength and approximately 4% greater aerobic capacity in the exercise group. That analysis also found favorable changes in some measurements of patellar cartilage.
So the exercise program did more than expose the participants to impact. It also improved aspects of physical capacity that are important for maintaining function with age.
Were There Injuries?
Yes, and this is worth including rather than presenting the study as risk-free.
Six medical consultations were required during exercise for issues including:
- Knee swelling
- Hamstring symptoms
- Ankle sprain
- Low-back pain
- Achilles tendon pain
- Asthma-like symptoms
There were no fall-related injuries during the exercise sessions, and all affected participants returned to training within approximately 5 to 21 days.
This is a useful reminder that “safe” does not mean “nothing uncomfortable ever happened.”
Exercise creates stress, and higher-impact exercise carries some risk. The relevant question is whether that risk is reasonable relative to the potential benefits and whether the program is appropriately screened, supervised, and progressed.
What This Study Does…and Does Not…Tell Us
This study provides good evidence that mild knee osteoarthritis does not automatically require avoiding impact exercise.
These women had documented knee OA and regular knee pain, yet they were able to participate in a progressive jumping and step-aerobic program for one year without measurable deterioration of the cartilage being studied.
At the same time, we should be careful not to apply the findings too broadly.
The participants were relatively young postmenopausal women (roughly their late 50s on average), had only mild radiographic osteoarthritis, were medically screened, and exercised under supervision.
Women with osteoporosis, substantial obesity, knee instability, previous knee surgery, inflammatory arthritis, and several other higher-risk conditions were excluded.
Therefore, this study does not establish that repeated high-impact jumping is appropriate for everyone with arthritis or osteoporosis.
It tells us something more specific and more useful:
When appropriately selected postmenopausal women with mild knee OA were progressively exposed to supervised high-impact exercise, femoral-neck strength improved without evidence of worsening knee-cartilage composition.
The Practical Lesson: Capacity Should Guide Progression
The most important part of this study may not simply be that the women jumped.
It is that the researchers used a 12-month progressive program.
Impact was gradually increased at roughly three-month intervals rather than introduced at maximal intensity immediately.
For someone who has been sedentary, has poor balance, has significant weakness, or has never practiced landing mechanics, jumping may not be the appropriate starting point.
A progression might instead begin with:
- Developing lower-body strength.
- Improving balance and single-leg control.
- Building calf, quadriceps, hamstring, and hip muscle mass.
- Increasing walking and stair tolerance.
- Introducing faster movements and controlled deceleration.
- Progressing to small jumps/hops/bounds (low-level impact).
- Gradually increasing jump height, direction, speed, or volume as appropriate.
The exact progression should depend on the person’s current ability, symptoms, bone health, joint health, training history, and other medical considerations.
That approach is very different from either extreme:
“You have arthritis, so avoid jumping.”
or
“Jumping builds bone, so everyone with low bone density should start jumping.”
Neither statement accounts for the individual.
Final Thoughts
The Multanen study challenges the idea that an arthritic knee must always be protected from impact.
In 80 postmenopausal women with mild knee osteoarthritis, 12 months of supervised, progressively intensified high-impact exercise increased estimated femoral-neck bending strength by roughly 4% without measurable deterioration in load-bearing knee cartilage. Participants also did not experience worsening knee pain, stiffness, or physical function compared with controls.
For women worried about both bone health and arthritis, that is encouraging.
The goal does not necessarily have to be eliminating stress from the joints.
Instead, the goal may be to build enough strength, balance, coordination, and tissue capacity that the body can gradually tolerate more stress.
For some women, that may eventually include jumping and other higher-impact exercise.
For others, the appropriate level of impact may be lower.
The important part is that the decision is based on the individual…not simply on the words “knee osteoarthritis” appearing in a medical chart.
Reference
Multanen J, Rantalainen T, Kautiainen H, et al. Effect of progressive high-impact exercise on femoral neck structural strength in postmenopausal women with mild knee osteoarthritis: a 12-month RCT. Osteoporosis International. 2017;28(4):1323-1333. doi:10.1007/s00198-016-3875-1.
