Shut up, legs: Fighting Parkinson’s with cycling and robotics

The effects of Parkinson’s are destructive: muscle tremors take hold, and the ravages of the disease render them stiff and slow. Now, a chance discovery by a US doctor has led to a breakthrough treatment which combines cycling with a cutting-edge robotic exoskeleton.

About 127,000 people in the UK are currently diagnosed with Parkinson’s

, with up to a million more sufferers living in the US. The disease progressively damages parts of the brain, with symptoms arising when the levels of a chemical messenger in the brain, dopamine, drop below normal levels. Medication can help, as can physiotherapy, but this unusual development delivers a surprising, two-wheeled twist.

A bicycle made for two

The discovery came during a roadtrip across Iowa. Dr Jay Alberts was working in the Biomedical Engineering Department at the Cleveland Clinic, Ohio, when he volunteered to take a friend with Parkinson’s on a week-long tandem ride across the American heartland. His motivation was simple: to demonstrate how an active lifestyle could, and should, be maintained after diagnosis.

To prepare, his friend trained for the trip on an exercise bike, pedalling at a steady rate of 60rpm. However, the trip provided her with an unexpected challenge: the tandem’s shared drive chain forced her to pedal roughly 40% faster in order to match Alberts’ swifter 85 rpm. Just two days into the trip, they were both surprised to notice that her symptoms had improved.

Amazingly, it wasn’t just her legs that showed fewer symptoms – her handwriting was better, too. Alberts decided to investigate.

He recruited 10 patients to take part in sessions on a tandem exercise bike. A qualified trainer sat on the front, as “captain”, and the patients sat behind, as “stoker”. The patients had to pedal as quickly as the fully-fit trainer for an hour each time, three times a week for two months.

The results were extraordinary and supported Jay’s suspicions. They showed a remarkable 35% improvement in motor functions and the effects persisted even four weeks after the tandem sessions had ended.

Significantly, the improvements were evident in the upper body, not just in the muscles that had done the pedalling. This was evidence that the assisted exercise had led to beneficial changes in the brain.

All this would be excellent news, if only tandem exercise bikes were common and easily accessible to Parkinson’s patients. Unfortunately, they are very rare. What’s more, it becomes increasingly costly if the sessions are one-to-one and require the services of a trainer to lead each workout.

A spin class – with a robotic twist

Fortunately, engineers at Kyungpook National University, South Korea, are developing an exoskeleton that could solve these problems.

The concept involves strapping robotic exoskeletal limbs to a rider’s own legs. These act as a stabilising force, making sure the wearer uses their own muscles in the right way to maximise the benefit of the exercise, and assisting them by adding power from in-built motors. Sensors in the electro-mechanical legs detect the how hard the wearer is pushing on the pedals, and automatically adjust how much assistance to give.

This frees the patient to ride on a common, single-saddle, static exercise bicycle on their own – no tandem required. What’s more, a personal trainer wouldn’t be tied to a single person during the session, and could attend to other patients at the same time.

It’s an ingenious solution. Instead of a tandem captain expertly regulating the forces and cadence, the robotic legs would be programmed to make sure the wearer is exerting enough effort during the exercise session to help alleviate their condition for weeks to come.

The results provide a ray of hope for sufferers worldwide. It’s thought that intense cycling can improve a variety of muscle functions, not just in the legs, if practiced in the early stages of the condition. By helping patients pedal more quickly, and smoothly, than they could unaided, the symptoms of Parkinson’s can be reduced.

It’s not about the bike

Building a powered machine that interacts intimately with the movement of a human being isn’t easy. The motorised limbs have to accurately track and mimic the kinematics of the hip, knee and ankle joints, so sensitive control mechanisms must be in place. After all, nobody will want to wear the device if it could manipulate their legs in an unsafe way.

It’s an immensely complex undertaking. The exoskeleton has sensors to measure the loads, angles and pitch at each joint, and to constantly monitor the pressure bearing down on each pedal. The data is analysed by the controlling computer, a 32-bit ARM Cortex chip. Commands are then sent to the 90W motors at the hips and more powerful 120W motors at the knees.

The first flush of experiments have confirmed that the system design is robust, but more work needs to be done to refine the design. The prototype will need more modifications and better sensors in order for the motion of the exoskeleton to conform more closely to the movement of human legs while pedalling.

There’s still a long way to go with this exceptional project but, when complete, it will offer hope of a better quality of life to Parkinson’s sufferers across the globe.