{"publication_id":"1ad636ff-4af7-42c3-9666-6fec14a4971c","content_hash":"sha256:9094d0afed377c6126d2849ce7ba92aad64f9e6a0bfb48e4b8503ce47cf55eff","nodes":[{"id":"1ad636ff-4af7-42c3-9666-6fec14a4971c","type":"publication","title":"Metformin blunts muscle hypertrophy in response to progressive resistance exercise training in older adults: A"},{"id":"claim_1","type":"claim","text":"10.1111/acel.13039 — role=evidence; design=randomized_trial; population=human; outcome=unspecified; direction=negative; support=direct/high; quote=\"placebo gained more lean body mass (p = .003) and thigh muscle mass (p < .001) than metformin … trend for blunted strength gai …\""},{"id":"claim_2","type":"claim","text":"10.1093/geroni/igy023.2009 — role=evidence; design=randomized_trial; population=human; outcome=unspecified; direction=positive; support=direct/high; quote=\"lean mass increased overall (P < 0.0001), with the metformin group gaining significantly less lean mass than the placebo group (P < 0.01) …\""},{"id":"claim_3","type":"claim","text":"10.3410/f.736671936.793569870 — role=replication; design=randomized_trial; population=human; outcome=unspecified; direction=negative; support=direct/high; quote=\"Faculty Opinions recommendation of Metformin blunts muscle hypertrophy in response to progressive resistance exercise training …\""},{"id":"claim_4","type":"claim","text":"Receipts describe feasibility-scale, randomized, double-blind, placebo-controlled trial evidence in adults aged 65+; no clinical advice is offered."},{"id":"source_1","type":"source","study":"Metformin blunts muscle hypertrophy in response to progressive resistance exercise training in older adults: A randomized, double‐blind, placebo‐controlled, multicenter trial: The MASTERS trial","year":2019,"doi":"10.1111/acel.13039","url":"https://doi.org/10.1111/acel.13039","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Progressive resistance exercise training (PRT) is the most effective known intervention for combating aging skeletal muscle atrophy. However, the hypertrophic response to PRT is variable, and this may be due to muscle inflammation susceptibility. Metformin reduces inflammation, so we hypothesized that metformin would augment the muscle response to PRT in healthy women and men aged 65 and older. In a randomized, double-blind trial, participants received 1,700 mg/day metformin (N = 46) or placebo (N = 48) throughout the study, and all subjects performed 14 weeks of supervised PRT. Although responses to PRT varied, placebo gained more lean body mass (p = .003) and thigh muscle mass (p < .001) than metformin. CT scan showed that increases in thigh muscle area (p = .005) and density (p = .020) were greater in placebo versus metformin. There was a trend for blunted strength gains in metformin that did not reach statistical significance. Analyses of vastus lateralis muscle biopsies showed that metformin did not affect fiber hypertrophy, or increases in satellite cell or macrophage abundance with PRT. However, placebo had decreased type I fiber percentage while metformin did not (p = .007). Metformin led to an increase in AMPK signaling, and a trend for blunted increases in mTORC1 signaling in response to PRT. These results underscore the benefits of PRT in older adults, but metformin negatively impacts the hypertrophic response to resistance training in healthy older individuals. ClinicalTrials.gov Identifier: NCT02308228."},{"id":"source_2","type":"source","study":"METFORMIN TO AUGMENT STRENGTH TRAINING EFFECTIVE RESPONSE IN SENIORS: THE MASTERS TRIAL","year":2018,"doi":"10.1093/geroni/igy023.2009","url":"https://doi.org/10.1093/geroni/igy023.2009","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Resistance training is the most effective method to increase skeletal muscle mass and strength in the elderly; however, the response in older individuals is variable and sometimes completely absent. We hypothesized that metformin would augment elderly participants’ response to training. At two study sites, participants were randomized to metformin or placebo and all performed resistance training for 14 weeks. Ninety-four participants completed the study and results were analyzed per-protocol. DXA showed that lean mass increased overall (P < 0.0001), with the metformin group gaining significantly less lean mass than the placebo group (P < 0.01). Similarly, thigh CT scans indicated that the metformin group gained less (normal density) muscle than placebo (P < 0.01). RNAseq analyses suggest that metformin may blunt training-induced changes in muscle gene expression. These data indicate that adjuvant metformin treatment does not enhance, and may actually blunt, the hypertrophic response to resistance training in elderly individuals."},{"id":"source_3","type":"source","study":"Faculty Opinions recommendation of Metformin blunts muscle hypertrophy in response to progressive resistance exercise training in older adults: A randomized, double-blind, placebo-controlled, multicenter trial: The MASTERS trial.","year":2020,"doi":"10.3410/f.736671936.793569870","url":"https://doi.org/10.3410/f.736671936.793569870","population":"not extracted","intervention_or_exposure":"not extracted","comparator":"not extracted","endpoint":"not extracted","effect":"not extracted","risk_of_bias":"not appraised in public sidecar","directness":"primary","excerpt":"Faculty Opinions recommendation of Metformin blunts muscle hypertrophy in response to progressive resistance exercise training in older adults: A randomized, double-blind, placebo-controlled, multicenter trial: The MASTERS trial."}],"edges":[{"from":"1ad636ff-4af7-42c3-9666-6fec14a4971c","to":"claim_1","type":"contains_claim"},{"from":"1ad636ff-4af7-42c3-9666-6fec14a4971c","to":"claim_2","type":"contains_claim"},{"from":"1ad636ff-4af7-42c3-9666-6fec14a4971c","to":"claim_3","type":"contains_claim"},{"from":"1ad636ff-4af7-42c3-9666-6fec14a4971c","to":"claim_4","type":"contains_claim"}],"screening":{"identified":3,"screened":3,"excluded":0,"included":3,"included_or_retained":3,"flow":["identified","screened","excluded_with_reasons","included"],"wording":"3 candidate receipts retained after source retrieval, deduplication, and topic filtering. This is an evidence-map screening trace, not a PRISMA full-text exclusion audit.","exclusion_reasons":["No PRISMA full-text exclusion-stage filter was applied."]}}