When older women lift weights for 8 weeks, their muscles don’t get much bigger, but they do get stronger and walk faster—so it seems like something other than bigger muscles is helping them move better.

A randomized controlled trial enrolling 100+ healthy older women (age ≥65), assigning them to either 8 weeks of supervised resistance training (3x/week, 70-80% 1RM, 3 sets of 8-12 reps) or a non-exercising control group, with pre- and post-intervention measurements of skeletal muscle mass (via DEXA), maximal strength (1RM leg press), and walking speed (4-meter gait speed), controlling for baseline nutrition and activity levels.

A longitudinal study tracking 50 older women undergoing 8 weeks of standardized resistance training, measuring skeletal muscle mass (MRI or DEXA), strength (isokinetic dynamometry), and walking speed at baseline, week 4, and week 8, with statistical modeling to assess whether changes in muscle mass correlate with functional gains.

A case-control study comparing 20 older women who showed no muscle mass gain but improved strength/walking speed after 8 weeks of resistance training ('functional responders') with 20 matched women who gained muscle mass but showed no functional improvement ('non-responders'), analyzing training adherence, muscle fiber type, and neural adaptations.

A meta-analysis pooling all published RCTs (n≥5) of resistance training in older women lasting exactly 8 weeks, with standardized reporting of skeletal muscle mass (DEXA), strength (1RM), and walking speed, to determine whether changes in muscle mass are consistently dissociated from functional improvements.

A series of N-of-1 trials in 5 older women undergoing 8 weeks of resistance training with daily monitoring of muscle mass (ultrasound), strength (handheld dynamometer), and walking speed, to identify individual patterns where functional gains occur without measurable muscle hypertrophy.