Target practice: How identifying motor synergies can enhance athletic training

How does a high-performance athlete get even better?

On the face of it, the answer seems simple: train harder. However, a recent study led by former PhD student Dr. Devon Frayne and Dr. Stephen Brown in the Department of Human Health and Nutritional Sciences suggests that a different approach may provide a more targeted form of training.

In a paper published in the Journal of Sports Sciences, the team of researchers compared how novice and experienced Nordic skiers moved during a bout of simulated skiing exercise. Their goal was to assess differences in motor synergies—essentially, processes by which the central nervous system can activate several muscles and move several joints cooperatively to complete a particular task.

“Motor synergies is a term that encompasses how people coordinate movements. Take a hand, for example: there’s a vast number of degrees of freedom. Each finger has several knuckles that can move in many different ways,” explains Brown. “Motor synergies is the idea that the brain can simplify the degrees of freedom by creating patterns where muscles and joints work together to achieve a common goal.”

When a motor synergy is developed, muscles and joints work as a cohesive unit, resulting in more controlled, consistent movement. Identifying motor synergies in sports movements might allow coaches and athletes to pinpoint areas where training might be most impactful, since they can be acquired with time and practice.

“We wanted to determine if athletes were prioritizing the control of certain movement features more than others, and if athletes’ control differed from that of inexperienced people,” says Frayne.

In order to identify motor synergies in Nordic skiers, the researchers recruited experienced skiers—individuals who had been skiing for years, some competing at the national level. By contrast, the inexperienced cohort comprised novices who had never skied before. All participants were set the same exercise task and wore reflective dots on different parts of their body, which allowed their movements to be tracked by multiple cameras.

Bringing Nordic skiing—also known as cross-country skiing—into the lab meant participants used a machine instead of gliding along a snowy track.

“We used a Skierg, which is like a rowing ergometer but for Nordic skiing. It measures power output based on how fast and how hard the user pulls,” explains Brown.

The Skierg simulates double-poling, a technique often used in Nordic ski racing. From a stationary standing position, users pull down with both hands simultaneously, reproducing the motion skiers use when pushing down with their poles.

Both experienced and novice participants displayed some form of motor synergy in their hands, upper arms, and whole-body centre of mass, suggesting that these components are crucial to the skiing movement and unlikely to change with experience. However, there were differences in where the motor synergies were expressed—and only experienced skiers also exhibited motor synergies in their trunk.

“Novices mostly focused on their hands, whereas experienced skiers used their whole body,” says Brown. “The latter were subconsciously controlling the movement of their trunk to a much greater extent, which tells us that this is something they learned over time.”

While motor synergies can be used to help athletes approach training from a novel angle, these findings are also meaningful for anyone looking to improve their performance at a given task.

“Measuring motor synergies is useful for exploring key movement features,” explains Frayne. “We can use this technique to determine which variables are relevant to the performance of a task and, from there, monitor changes in response to different interventions.”

By providing an early indication of the impact of interventions on the musculoskeletal system, measuring motor synergies can be meaningful in a variety of contexts, including physical therapy programs.

Of course, the results from this study are useful for any Nordic skier wishing to improve their technique.

“If someone wanted to begin training, they could see from our findings that hand velocity and trunk velocity during the early part of the movement are key variables to monitor training progress,” says Frayne.

Future studies are already in the works to monitor motor synergies and short-term adaptations to exercise—research that will benefit anyone looking to teach their brains to control movements in different ways, from weekend warriors to competitive racers.

Read the full study in the Journal of Sports Sciences.

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