aqua fitness

Navigating Knee Pain: How Aquatic Exercise Can Be Used To Support Your Workouts

Dr Sophie Heywood, PhD from Hydro Functional Fitness explains how aqua-based activities can help keep people with a history of knee issues, engaged in exercise for the long-term.

It’s not your imagination; you are likely to be working with more people with knee pain in recent times. The total number of knee injuries have been increasing over the last 20 years, as has the prevalence of knee osteoarthritis. Fitness professionals play a key role in the team effort to keep people with a history of knee issues engaged in exercise in the long term.

Most knee pain is ‘chronic’ or ‘persistent’. This means it’s been around for a good couple of months or longer, in some cases, years. If your client is over 45 years old and has pain on activity or movement (and less than 30 minutes of morning stiffness), then they’re likely to have knee osteoarthritis. The risk factors to developing knee arthritis are surprising to some as it’s not really about just getting older, many of your younger clients may fit in this category. Some of the risk factors can include previous injury (such as a meniscal tear or ligament injury like an anterior cruciate ligament rupture), being overweight or obese or having an occupation that involved a lot of load on the knee like being a tradie. A family history of osteoarthritis is also a risk factor.

For people with knee osteoarthritis, research shows that the health benefits of physical activity are significant and exercise is recommended for everyone with knee osteoarthritis, regardless of the severity, how much pain people have or how hard it is for them to move around (NICE, UKAmerican College of RheumatologyOARSI, Royal Australian College of GPs).

Here is an overview of five key considerations when you’re working with someone with knee osteoarthritis.

graded exposure to load

Start gradually and build up slowly based on how your client’s pain system tolerates any new exercises. This is called ‘graded exposure to load’. We do want to reinforce the resistance training principle ‘progressive overload’ for strength gains, but keeping any changes or increases in resistance with exercise slow and steady will work best.

Aquatic exercise can be a more gentle way to start with exercise to build confidence and see some early improvements in muscle performance. With water up to the waist, there is 50 per cent less body weight load (and 70 per cent less body weight load in chest deep water). Exercises in water can be less painful than exercises on land for people with knee osteoarthritis and people recognise it is lower load and creates less strain on the joint.

effective exercise options

Specifically for knee osteoarthritis, the most beneficial types of exercise in most guidelines are cardiovascular exercise and lower limb strengthening (in particular it’s useful to strengthen quadriceps and hamstrings to support and steady the knee joint as well as gluteals and the calf muscles). Balance exercises are also useful for some people and if stiffness is a problem, stretching may be good. All of these types of exercises can be done in water if someone isn’t tolerating them in the gym.

education about pain with exercise is important

Small amounts of joint pain during and after exercise with arthritis is normal. Pain does not necessarily mean there is damage being caused to the joint. The fitness professional is ideally placed to reinforce this. In time, with slow and small increases in exercise, the whole system will become less sensitive and your client’s pain will improve. In reality, this may take several months but the aim is for the joint pain to be at a ‘reasonable’ level from the client’s perspective and ideally not more than a couple of hours after exercise. Delayed onset muscular soreness (DOMS) can, of course, mean it’s not unusual to have discomfort for 48 hours after exercise. However, if your client has pain beyond DOMS for more than 24 hours, you can recalibrate and do less next time; or have them consult a health professional if it doesn’t settle. The key is to understand and educate clients that pain does not always equate to damage having been sustained.

supporting your client for long-term success with exercise


For any specific workout or exercise program to be a success, your client must feel like they have some input and control. Be open to them guiding how you progress and keep checking in often on how they are feeling, their confidence, feedback from their health professional team, their motivation levels and goals. The biggest blocker for people sticking with exercise in the long-term is often a bad experience with being pushed too hard and too quickly with exercise. Incorporate rest days and general advice on wellbeing.

Pain does not necessarily mean there is damage being caused to the joint.

use lower-load exercise options in a flare

High-impact activities might not be the right fit for your client if they are struggling with increased knee pain or in a flare (which is a short-term exacerbation of pain). As a fitness professional, guide them toward lower-impact exercises at this time. Cycling, or a cross-trainer are all good options with isometric strengthening progressing slowly back to low levels of resistance.

Swimming can be a good option for cardiovascular conditioning. Shallow water aquatic exercise has been shown to be just as effective in improving pain and walking for people with knee osteoarthritis. In a survey of more than 500 people, nearly three-quarters of people with knee pain have tried aquatic exercise to help manage their knee pain and this could be a good option, for a period of time to help your clients manage their pain, stay engaged with exercise and get the best results in the longer term.

Sophie Heywood2

Dr Sophie Heywood, PhD

Dr Sophie is an APA Sports and Exercise Physiotherapist with a PhD in the biomechanics of functional exercise and aquatic rehabilitation for people with knee osteoarthritis. Sophie works at Hydro Functional Fitness, the Melbourne Sports Medicine Centre and St Vincent’s Hospital Melbourne. Hydro Functional Fitness is innovating with more ways to keep people exercising successfully in water and offers online aquatic exercise programs for people with musculoskeletal conditions.