Both power and strength training can improve muscle performance in people with Parkinson’s disease, but these improvements may not translate to functional movement, a new study has found.
The study, titled “Power vs strength training to improve muscular strength, power, balance and functional movement in individuals diagnosed with Parkinson’s disease,” was published in Experimental Gerontology.
Strength and power training are forms of progressive resistance training (PRT) — what’s normally called “lifting weights,” although the process often involves more complex machinery than barbells — where a muscle is worked against some form of resistance (e.g. lifting something heavy, in which case the resistance is gravity).
The difference between the two is that strength training focuses on increasing the total resistance that a muscle can move (lifting heavier weights), whereas power training is more concerned with doing lower-resistance reps at faster speeds.
In the study, researchers wanted to find out if PRT improves muscle strength in people with Parkinson’s disease and their ability to function independently. They conducted a clinical trial (NCT03434327) with 35 people with mild-moderate Parkinson’s disease (23 male, 12 female, average age was 71 years), who were randomly assigned to complete a 12-week course of either strength training or power training, consisting of two hour-long sessions per week.
The researchers then assessed the participants’ muscle strength (maximum weight they could move) and power (fastest speed they could move a not-maximum weight), as well as other assessments such as their balance and quality of life.
Patients in both groups showed a significant improvement after the 12-week intervention in their ability to perform chest and leg presses. However, there was no significant difference between the two groups.
The same pattern was observed for muscle power: Participants experienced significant improvement in both chest and leg presses, but there was no difference between the two groups.
Over time, both groups demonstrated a decrease in balance scores (measured via the Berg Balance Assessment) that, while statistically significant, was not considered clinically significant. In other words, the improvement in balance wasn’t due to chance, but it probably didn’t have much impact on the participants’ day-to-day lives.
Other functional measurements, including fear of falling (measured by the Modified Falls Efficacy Scale) and functional mobility (assessed via time-up-and-go test) did not differ between the groups over the course of the study.
Similarly, results from the Parkinson’s Disease Questionnaire-39, an assessment of quality of life for people with Parkinson’s, suggested no differences over time or between the groups in terms of ability to perform tasks required for daily living.
The fact that increased muscle performance didn’t translate into better functionality wasn’t entirely unexpected, the researchers said, noting that past studies have yielded conflicting results in the elderly, and in Parkinson’s patients.
“Given that subjects in both the [power training] and [strength training] groups demonstrated significant improvements in muscular strength and power, both PRT programs appear helpful in addressing these neuromuscular performance variables,” the researchers said.
“Since we did not observe any functional benefit in our sample, the inclusion of movement-specific training components that target balance, mobility and [activities of daily living] performance appears warranted in any PRT program,” they added.