Writing in the Archives of Gerontology and Geriatrics, researchers said the study has shown that the combination of catechin-enriched green tea and exercise could have a beneficial effect on muscle strength.
A total of 78 seniors aged 60 and above who reported self-perceived weakness or slowness and took three or fewer cups of green tea per day participated in this 24-week randomized controlled trial.
During the study, they were randomized to undergo an exercise regimen and either consume a catechin-enriched green tea powdered drink or a placebo.
Each 2.3 g soluble powder stick of catechin-enriched green tea contained 306.5 mg catechin. The same amount of the placebo-soluble powder stick had 14.3 mg of catechin.
Participants had to take two sticks of the powdered drink dissolved in water every day for 24 weeks.
The test materials were provided by the Research Institute of ITO EN.
The participants also attended weekly exercise sessions that included lower limbs exercise, resistance training using elastic bands, balance training and dual-task exercises.
To measure the potential effects of green tea catechins, urine samples of the participants were collected at the baseline and the end of the 24-week study.
Knee extension strength improved
Findings showed a significant improvement in knee extension strength among participants who exercised and took green tea as compared to the placebo.
This was when researchers treated participants who developed orthopedic conditions - such as spinal stenosis and spinal and foot fractures unrelated to the intervention — as having missing post-intervention values.
These participants were assigned missing post-intervention values as researchers explained that these orthopedic conditions could plausibly affect the study outcomes.
Based on this assumption, the researchers had indeed found a significant difference in knee extension strength between the intervention and placebo groups.
“Under this assumption, the group × time interaction for knee extension strength became statistically significant, suggesting a between-group difference," researchers wrote.
Analysis of the percentage changes in knee extension strength before and after the study also showed significant differences between the two groups.
“Comparisons of percentage changes between groups based on the intent-to-treat analysis indicated that the percentage change in knee extension strength over 24 weeks differed significantly between the intervention (116.1%) and control (92.6%) groups,” researchers wrote.
The researchers attributed green tea catechins’ benefits to its anti-oxidative, anti-inflammatory and mitochondria-enhancing effects.
They also highlighted that green tea catechins supplementation could increase isokinetic flexor muscle and handgrip strength in a 12-week study.
Aside from knee extension strength, however, there were no statistically significant differences in physical performance tests or muscle mass between the groups before and after the current study.
Effects on Titin N-terminal fragment
Participants who took green tea catechins also showed a decrease — albeit statistically non-significant — in the amount of titin N-terminal fragment in their urine samples.
The urinary titin N-fragment has been reported to be a useful biomarker for the diagnosis of muscle dystrophy, such as amyotrophic lateral sclerosis, muscular dystrophy, and ICU-acquired weakness.
A recent longitudinal study also indicated that higher urinary Titin N-fragment levels predict sarcopenia onset in community-dwelling adults with type 2 diabetes.
“The negative association between the catechin consumption using the study beverages during the 24-week study period and changes in urinary Titin N-terminal fragments, with no association with placebo drink, indicates the positive effects of catechin on muscle damage protection among relatively healthy community-dwelling older adults,” researchers wrote. They have also urged further studies to assess other biomarkers related to muscle health.
Source: Archives of Gerontology and Geriatrics. doi: 10.1016/j.archger.2026.106260. “Effects of catechin-enriched green tea combined with exercise on physical performance and muscle mass in community-dwelling older adults: A cluster-randomized, placebo-controlled trial.” Authors: Hyuma Makizako et al.
