An isokinetic dynamometer is worth buying when your clinic makes strength decisions that need a number behind them: return to sport after ACL reconstruction, shoulder rehab in overhead athletes, or tracking strength loss in older adults. If that is a weekly event for your team, a dynamometer pays its way through better decisions and a service you can charge for. If it's a few times a year, a handheld dynamometer and a referral pathway will probably do the job.
This guide covers what an isokinetic system measures, who gets the most out of one, and the questions to settle on space, software, service and budget before you ask for a quote.
What an isokinetic dynamometer does
An isokinetic dynamometer holds a limb at a set angular speed while the patient pushes or pulls as hard as they can. Because the machine controls the speed, it can measure the force produced across the whole range of motion, not just at one point. That gives you peak torque, the angle where it occurs, work, power and fatigue across repeated efforts.
Most modern systems do more than isokinetic work. The ISOFORCE system that Rehab Technology supplies runs six modes: isokinetic, isometric, isotonic, concentric, eccentric and CPM (continuous passive motion). That matters, because the same machine can test a post-op knee in passive mode in week two and run a full return-to-sport battery at month nine.
Who gets the most value from one
Three groups tend to get a fast return.
Sports medicine and physiotherapy practices with a steady ACL, hamstring or shoulder caseload use isokinetic testing to set clear criteria for return to play. Our earlier article on why objective strength testing is changing return-to-play decisions goes into the clinical case in more detail.
Universities and research labs need repeatable, exportable data for studies and teaching. If that's you, the universities and research facilities page shows the wider testing range.
Hospitals and rehab centres use dynamometry for orthopaedic and neurological caseloads, and increasingly for older adults where strength loss drives falls risk and loss of independence.
If your caseload is mostly general musculoskeletal work with the odd post-op knee, be honest about utilisation. A system that sits idle four days a week is hard to justify.
Why the numbers matter for return to sport
Clinicians have long used a limb symmetry index (LSI), the injured side as a percentage of the uninjured side, to judge readiness. The common cut-off is 90%. A 2021 review in the International Journal of Sports Physical Therapy argued that bar is too low. The authors noted that patients who passed 90% still showed meaningful strength deficits in both legs compared with healthy athletes. They suggested athletes aim for 100%, with 90% as the lower limit for isokinetic strength testing.
You can only work to that standard if your measurement is reliable. Handheld devices are useful screening tools, but they depend on the tester's strength and positioning. An isokinetic system fixes the speed, the axis and the stabilisation, so a retest in six weeks is comparing like with like.
Features to compare before you buy
Testing modes. Check you get isokinetic, isometric and isotonic at minimum, plus eccentric work if you treat tendinopathy or hamstring injuries. Passive or CPM mode is useful for early post-op patients.
Joints and movement patterns. Knee and shoulder testing are the core. Ask how many joint patterns the attachments cover and how long a changeover takes. ISOFORCE lists more than 20 joint movement patterns across upper and lower limb.
Software and reports. This is where you will spend most of your time. Look at what the report shows a patient, a surgeon or a coach. Useful outputs include peak torque, force-velocity profiles, limb symmetry, fatigue index and endurance curves. Ask whether data exports cleanly for research or your practice software.
Real-time feedback. On-screen feedback during a test helps patients give a true maximal effort, which improves the quality of the data. It also turns the machine into a training tool between tests.
Seat and stabilisation. Good straps and a firm, adjustable seat are what make results repeatable. Check adjustment for taller athletes and for older or frailer patients who need help to transfer.
Space, power and installation
Measure before you shortlist. The ISOFORCE unit is 200 x 70 x 170 cm (length x width x height), according to the product page. On top of that you need clear room on the working sides for patient transfers, a wheelchair approach if your caseload needs it, and the clinician standing at the console.
Things to confirm with the sales team early:
- Floor loading and access route, including doorways, lifts and stairs on delivery day
- Power supply at the planned spot
- Whether the room doubles as a treatment or gym space, and how you will manage testing sessions around that
Rehab Technology ships Australia-wide. Local technicians cover the capital cities and larger regional centres, and remote sites get a planned technician visit for installation and servicing.
What drives the cost
Isokinetic dynamometers sit at the capital-equipment end of a rehab budget, and pricing is quoted to your setup rather than listed online. The main things that move the number are:
- The attachment package. A knee-and-shoulder kit costs less than a full upper and lower limb set.
- Software options and any research or export add-ons.
- Console choices, for example a touch screen.
- Delivery, site access and installation.
- Ongoing service and calibration.
When you compare quotes, compare the whole-of-life cost, not the sticker. A cheaper unit with slow local service can cost you more in lost testing sessions than it saved up front. Our guide to choosing rehab equipment that delivers long-term ROI walks through that maths.
Questions to ask before you sign
- Who services it locally, and what is the usual response time for a fault?
- How is calibration checked, and how often?
- Which attachments are included, and which are extra?
- Can the software export raw data, and in what format?
- What happens to your stored patient data if you upgrade the computer or console?
Get the answers in writing with the quote. They are easy to ask now and hard to fix after install.
Building the business case
A simple business case answers three questions.
How many tests a week will you run? Count current ACL, shoulder and hamstring patients, plus any athletes or teams you report to.
What will you charge? Many practices bill a formal strength assessment as a separate service with a written report. Check your own fee schedule and what local referrers expect.
What else does it do? Use between tests for isokinetic and eccentric training adds value. So does the referral pull from surgeons and sports teams who want objective clearance data.
If the numbers are marginal, start with a handheld option such as the ActivForce 2 digital dynamometer from the evaluation and measurement range. Track how often you wish you had full isokinetic data. That log becomes your business case later.
About ISOFORCE
ISOFORCE is made in Germany by TUR, a medical technology company that traces its history back to 1904. Rehab Technology supplies it as part of a human performance technology range built around the return-to-play pathway. There are no published Australian case studies yet, so the figures in this guide come from the manufacturer's specifications and independent research.
Frequently asked questions
What is an isokinetic dynamometer used for?
It measures muscle strength at a fixed joint speed through the full range of motion. Clinics use it for return-to-sport testing after ACL and shoulder injuries, tracking strength in orthopaedic and neurological rehab, and research.
Is isokinetic testing better than a handheld dynamometer?
For repeatable return-to-sport decisions, yes. An isokinetic system controls speed, joint axis and stabilisation, so retests compare like with like. Handheld dynamometers are cheaper and portable, and work well as a screening tool.
How much space does an isokinetic dynamometer need?
The ISOFORCE unit measures 200 x 70 x 170 cm. Allow extra clear space on the working sides for patient transfers, wheelchair access and the clinician at the console.
What limb symmetry index should athletes reach before returning to sport?
Ninety per cent has been the common cut-off, but a 2021 review in the International Journal of Sports Physical Therapy recommended aiming for 100%, with 90% as the lower limit for isokinetic strength testing.
Who services isokinetic equipment in Australia?
Rehab Technology ships Australia-wide. Local technicians cover the capital cities and larger regional centres, and remote sites get a planned technician visit.
Next step
If you're weighing up an isokinetic system for a clinic, hospital or lab, the sales team can look at your caseload, room and budget and tell you straight whether it stacks up. Talk to a Specialist.
Sources
- Unverzagt C, Andreyo E, Tompkins J (2021). ACL return to sport testing: it's time to step up our game. International Journal of Sports Physical Therapy.
- ISOFORCE / TUR, About us.
