Lab Notes · 6 min read

Why we measure your grip, your balance, your heart rate and your posture

Your first visit here is a Longevity Analysis. It takes twenty-five minutes and reads six markers on instruments. People ask why these six, and why a gym is measuring grip strength and balance at all. This Lab Note answers that, one marker at a time.

Grip strength

Grip strength is read on a hand dynamometer. It is how researchers measure whole-body strength, because your grip tracks with the rest of you. You are not training your hands.

The PURE study followed nearly 140,000 adults in seventeen countries. Lower grip strength came with a higher risk of dying from any cause and from heart disease, and the authors found grip was a stronger predictor of both than blood pressure.

Leong et al. (PURE), Lancet 2015;386:266–273

The largest review since pooled more than three million people. The risk kept falling as grip went up, across the whole range it studied.

López-Bueno et al., Ageing Research Reviews 2022;82:101778

Lean muscle mass

Muscle mass relative to your height is called a lean mass index. Older adults with the most muscle for their height lived longer than the ones with the least, whatever the scale said about them.

Srikanthan & Karlamangla, American Journal of Medicine 2014;127(6):547–553

Body fat

Body fat is read by bioimpedance, a small current that tells fat and lean tissue apart. A review of 72 studies found every common measure of fat around the middle rose with the risk of dying from any cause.

Jayedi et al., BMJ 2020;370:m3324

Resting heart rate

Resting heart rate reflects how efficient your heart is. A lower one means more blood moved per beat and the recovery side of your nervous system in charge. The Copenhagen Male Study followed 2,798 men for sixteen years, and their risk of dying rose with every ten beats. A review of more than a million people confirmed it.

Jensen et al., Heart 2013;99(12):882–887

Zhang, Shen & Qi, CMAJ 2016;188(3):E53–E63

Balance

Balance takes input from your eyes, your inner ear and the position sense in your joints. The inner-ear system is called the vestibular system, and the position sense is called proprioception. Adults aged 51 to 75 who could not stand on one leg for ten seconds were far more likely to die over the next seven years than those who could.

Araujo et al., British Journal of Sports Medicine 2022;56(17):975–980

We test it with your eyes closed. That removes vision and tests the vestibular and proprioceptive systems on their own.

Posture

Posture is read with a movement screen. It finds what your body is compensating for, and why something aches. A rounded upper back, called hyperkyphotic posture, went with a higher death rate in older adults followed over several years.

Kado et al., Journal of the American Geriatrics Society 2004;52(10):1662–1667

Why one number

The Longevity Analysis combines them into one score out of 600, a letter grade and a biological age, and runs them again every six weeks on the same instruments, the same way. That is how you know the change is real.

What moves those numbers is training that is heavy enough, every session.

The whole gym runs on an AI-based strength measurement system. Artificial intelligence reads exactly what level of effort you are putting in on every repetition, and it makes sure you are in the right strength-building and muscle-building zone at all times. No junk reps.

The full research for all six is on The Research page.

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Twenty-five minutes. No charge. You walk out with your numbers.

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