Quercetin ingestion alters motor unit behavior and enhances improvement in muscle strength following resistance training in older adults: a randomized, double-blind, controlled trial.
Study Goal
The researchers aimed to determine whether daily quercetin glucoside ingestion enhances muscle strength and motor unit adaptations in older adults undergoing resistance training.
Results Summary
Quercetin ingestion (200 mg/day) led to greater improvements in maximal voluntary force compared to placebo, with increased firing rates in motor units with higher recruitment thresholds, suggesting enhanced neuromuscular adaptations. Muscle mass remained unchanged in both groups.
Population
Healthy older adults
Effective Dosage
200 mg/day
Duration
6 weeks
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
quercetin glucoside ingestion | increase | motor unit (MU) with a higher recruitment threshold | older adults | - | can enhance | #1 |
6-week resistance training intervention with the ingestion of quercetin glycosides (QUE) at 200 mg/day | increase | knee extensor maximal voluntary force (MVF) | healthy older adults | 115.1 ± 11.0% | significantly increased | #2 |
6-week resistance training intervention with the ingestion of placebo (PLA) | increase | knee extensor maximal voluntary force (MVF) | healthy older adults | 105.3 ± 4.8% | significantly increased | #3 |
6-week resistance training intervention with the ingestion of quercetin glycosides (QUE) at 200 mg/day | no change | muscle mass | healthy older adults | - | was not changed | #4 |
6-week resistance training intervention with the ingestion of placebo (PLA) | no change | muscle mass | healthy older adults | - | was not changed | #5 |
6-week resistance training intervention with the ingestion of quercetin glycosides (QUE) at 200 mg/day | increase | firing rates of MUs with relatively moderate recruitment thresholds (recruited between 20 and 40%MVF) | healthy older adults | - | were higher | #6 |
6-week resistance training intervention with the ingestion of quercetin glycosides (QUE) at 200 mg/day | increase | firing rates of MUs with relatively higher recruitment thresholds (recruited between 20 and 40%MVF) | healthy older adults | - | were higher | #7 |
QUE ingestion | increase | muscle strength | - | - | explain the greater improvement | #8 |
BACKGROUND: During resistance training, quercetin ingestion can enhance motor unit (MU) with a higher recruitment threshold in older adults. OBJECTIVE: We investigated the effects of daily quercetin glucoside ingestion on chronic adaptations in muscle strength and MU behavior following resistance training in healthy older adults. METHODS: Twenty-six older adults were randomly allocated to two groups that completed 6-week resistance training intervention with the ingestion of either placebo (PLA) or quercetin glycosides (QUE) at 200 mg/day. Maximal voluntary force (MVF) during isometric knee extension, muscle mass, and MU firing behavior during ramp task at 70%MVF were measured before (PRE) and after (POST) intervention. RESULTS: In both groups, knee extensor MVF was significantly increased (both p < 0.001), and the improvement in QUE (115.1 ± 11.0%) was greater than in PLA (105.3 ± 4.8%) (p < 0.001) by the Mann-Whitney test. Muscle mass was not changed from PRE to POST in PLA or QUE (p > 0.050). At POST, firing rates of Mus with relatively moderate (recruited between 20 and 40%MVF) or higher (recruited between 20 and 40%MVF) recruitment thresholds were higher in QUE than PLA (p < 0.050). There was a significant correlation between %change in MVF and %change in firing rates of MUs with a relatively higher recruitment threshold from PRE to POST (p = 0.018, r = 0.642). CONCLUSIONS: These results suggest that the adaptations of MUs with higher recruitment thresholds explain the greater improvement in muscle strength associated with QUE ingestion. CLINICAL TRIAL REGISTRY: UMIN000053019 ( https://rctportal.niph.go.jp/detail/um?trial_id=UMIN000053019 ).