Single-Arm Resistance Training Study to Determine the Relationship between Training Outcomes and Muscle Growth Factor mRNAs in Older Adults Consuming Numerous Medications and Supplements.

OBJECTIVES

Determine if the muscle mRNA levels of three growth factors (insulin-like growth factor-1 [IGF1], ciliary neurotropic factor [CNTF], and vascular endothelial growth factor-D [VEGFD]) are correlated with muscle size and strength gains from resistance exercise while piloting a training program in older adults taking medications and supplements for age-associated problems.

DESIGN

Single-arm prospective study.

SETTING

US Veterans Affairs hospital.

PARTICIPANTS

Older (70±6 yrs) male Veterans (N=14) of US military service.

INTERVENTION

Thirty-five sessions of high-intensity (80% one-rep max) resistance training including leg press, knee curl, and knee extension to target the thigh muscles.

MEASUREMENTS

Vastus lateralis biopsies were collected and body composition (DEXA) was determined pre- and post-training. Simple Pearson correlations were used to compare training outcomes to growth factor mRNA levels and other independent variables such as medication and supplement use.

RESULTS

Average strength increase for the group was ≥ 25% for each exercise. Subjects averaged taking numerous medications (N=5±3) and supplements (N=2±2). Of the growth factors, a significant correlation (R>0.7, P≤0.003) was only found between pre-training VEGFD and gains in lean thigh mass and extension strength. Mass and strength gains were also correlated with use of α-1 antagonists (R=0.55, P=0.04) and pre-training lean mass (R=0.56, P=0.04), respectively.

CONCLUSIONS

Muscle VEGFD, muscle mass, and use of α-1 antagonists may be predisposing factors that influence the response to training in this population of older adults but additional investigation is required to determine if these relationships are due to muscle angiogenesis and blood supply.