New guides target strength training for runners and military

The Numbers Behind the Shift

A study published in JAMA Networks this February found a connection between greater muscular strength and lower mortality in women aged 63 to 99, even among those not meeting guideline-recommended activity levels. A separate Mayo Clinic study of 3,889 adults produced a sharper signal: participants in the lowest muscle power bracket carried roughly six times the mortality risk of those in the highest bracket. Low strength, after adjusting for other factors, was not significantly associated with mortality.

The distinction is mechanical. Strength is the maximum force a muscle can produce. Power is the rate at which that force is applied — the ability to catch a stumble, clear a curb, or rise from a chair before momentum dissipates. Dr. Karlie Intlekofer, Global Research Scientist at Matrix Fitness, identifies power as the more decisive variable for fall risk and the preservation of independent movement.

Why Power Erodes Faster

Power output depends heavily on fast-twitch motor units, which decline more rapidly than slow-twitch fibers with age. The mechanism: neural drive and fiber-type composition shift earlier than absolute force capacity. A lifter can retain one-rep-max strength deeper into older age while losing the rate component well before. Standard machine-based loading — fixed weight, controlled tempo — trains force production without systematically stressing speed.

Translating the Research into Programming

Three levers force the issue:

• Intent to move fast. Light-to-moderate loads driven with maximum concentric velocity target the rate component. Heavy slow grinding does not.
• Speed as a progress metric. Bar velocity or jump height tracked across sessions reveals decay long before load stalls.
• Ballistic work early in the session. Jumps, med ball throws, and explosive variations recruit the fast-twitch pool when the nervous system is freshest.

The new tools — the NASM report and LiftTrack's Garmin-linked platform — both attempt to externalize feedback loops most lifters lack. Whether they change behavior or simply quantify existing stagnation remains the open variable.