https://onlinelibrary.wiley.com/doi/10.1002/lim2.90
Very interesting paper on muscle mass vs strength in predicting cognitive function declines. Strength is what matters.
Here’s a podcast talking about it. (Not mine)
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If my grip strength and powerlift metrics are high, my bodyfat is low and my BMI good, yet my last DEXA said I had a poor appendicular lean mass index (ALMI) vs. my age-matched peers, am I still actually doing okay? Is my ALMI percentile ranking poor because the population is obese? DEXA did tell me that I’m quite lean vs. the population.
I hope that ALM/BMI and strength/weight ratios are more relevant than ALMI, because my ALM/BMI is high vs. the population. Peter Attia’s emphasis on ALMI has had me thinking that I’m severely under-muscled in spite of my strength level, but that never made sense to me. This paper suggests that he’s not considering that overfed people have more muscle, but accrued for non-ideal reasons and consisting of dubious quality.
In addition, when examined as a continuous variable, muscle mass (as FFMI) was not associated with self-reported physical activity levels. This suggests that the majority of muscle mass in this cohort was accrued as a part of greater total body mass. In line with this, higher muscle mass was associated with higher fat mass as well as higher HbA1c, indicating worse glycemic control with increasing total body mass. Associations between muscle mass and health outcomes in datasets such as NHANES are therefore likely to be confounded by the way in which muscle mass is accrued.
Furthermore, Mesinovic and colleagues reported a positive relationship between waist circumference and greater muscle size, but poorer muscle strength and quality.
it is perhaps not surprising that low muscle mass and cognitive function were weakly positively related. Indeed, the opposite of some of the expected relationships were seen, with those in the low ALMI/FFMI groups also having lower HbA1c levels. This may be explained by broader associations between muscle mass, fat mass, and overall health. For instance, the FFMI Z-score was positively associated with HbA1c. In males in particular, those with normal ALMI had higher waist circumferences despite similar levels of body fat. This may suggest that males in the normal ALMI group had higher levels of visceral fat, which is known to be associated with higher levels of systemic inflammation and worse metabolic health.45
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A few thoughts / guesses:
- lifting skill matters, perhaps your strength is more skill based than your peers
- power / strength is also related to the ability to recruit more muscle fibers to work at one time.
- hydration differences?
- fiber type differences: fast twitch are bigger but hold less mitochondria (also counted in muscle mass) than slow twitch. Fast twitch is what we lose as we age.
If you feel strong, you are.
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Hmm, good points to consider. Fast twitch loss does concern me, as box jumps are harder (scarier) than they used to be.
Any middle-aged man who thinks he’s strong should look at female national-level raw powerlifting competition results and prepare to be humbled. 
I have no idea what strong really means. “Strong enough” is a bit easier since I can tie those words to specific tasks.
What I’m still struggling with is whether ALMI is still meaningful if absolute and relative strength are already decent. If muscle mass independent of strength is important for healthspan and/or lifespan, then a hypertrophy-focused program and eating a caloric surplus may be necessary. Yet that means many hours of lifting per week and a lot of mTOR activation. Maybe this isn’t ideal since there’s some (weak) evidence suggesting that too much lifting may increase mortality. Personally, I favor the lifting because I enjoy it.
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Excellent study. (because I like the outcome 
)
Except for some diabetes risk reduction there is no need to overdo it.
"The dose-response meta-regressions suggest that ~30-60 minutes of resistance training per week is associated with the largest risk reduction for all-cause mortality, cardiovascular disease incidence, and cancer rates (Figure 2). Furthermore, for these three outcomes, there appear to be no risk reductions (and possible increases in risk) for individuals performing more than 130-140 minutes of resistance training per week.
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Food for thought. I always squeeze in 3 60 minute resistance training workouts a week but 2 would be healthier I bet. I just like it.
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haha. Yes, well I don’t like the outcome so I’m going to hang my biased hat on these repeated statements: “The overall quality of the evidence on all-cause mortality [CVD, total cancer] was rated as ‘very low’” and pretend I never came across the analysis.
It appears that someone did a review of the review to compound the metas and inject speculation, but it’s paywalled. Optimum Dose of Resistance Exercise for Cardiovascular Health and Longevity: Is More Better? | Current Cardiology Reports
While it remains unclear, postulated mechanisms that may underlie the higher CVD risk and mortality with higher resistance exercise doses include increased arterial stiffness and chronic inflammation.
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I never begrudge people working out as much as they want. When I was young my family couldn’t understand why I wanted to run 2 or 3 miles every day.
It was the endorphins. At mile two, I almost always experienced “runners high” but by mile three it started to decrease.
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