Prologue: I write these blogs to separate what’s popular from what’s most impactful in preventive cardiology and healthy aging. As you may know from my earlier posts, I am skeptical - but not dismissive - of many modern health tools and trends. Today, I want to highlight approaches that are actionable and reflect my core belief: lifestyle is the most powerful medicine when used thoughtfully.
Why Generic Activity Goals Fall Short
Most people are familiar with broad health advice like “10,000 steps a day” or “30–60 minutes of daily activity.” These goals are useful starting points for sedentary people, but they fall short for weight loss and long-term fitness. They are enough to keep a person upright and mobile, but not enough to age well, avoid injury, stay strong, or recover from illness. Once a basic foundation is in place, we need to do better at guiding people toward exercise that maintains strength and independence. In that spirit, I want to explore three approaches that go beyond generic advice and can make exercise truly impactful.
VO₂ Max: The Gold Standard for Fitness
We often tell patients to “move more,” but rarely give them a roadmap for how to move in a way that improves cardiorespiratory fitness and metabolic efficiency. Cardiorespiratory fitness, best measured by VO₂ max (the amount of oxygen your body can use, adjusted for body weight), is the single best descriptor of overall cardiopulmonary health and one of the strongest independent predictors of all-cause and cardiovascular mortality (Kodama, 2009). Even small increases in VO₂ max are linked to reduced mortality risk. The American Heart Association has recommended that cardiorespiratory fitness be assessed as a “vital sign” in clinical practice (Ross, 2016).
In clinic, I’ve observed that people often misjudge their fitness level. When asked about activity, they tend to recall what they used to do - playing on a sports team in high school, running 5Ks in their forties, or describing their most active years - rather than their current routine. Self-reported activity often is inaccurate compared with objective testing, which is why experts emphasize measuring it directly (Ross, 2016).
VO₂ max testing helps solve that problem by providing a precise measurement. More importantly, it offers actionable insights: personalized heart rate zones for training, identification of the heart rate where fat oxidation peaks, and a clearer sense of what “moderate intensity” really means. This matters because regular exercise at moderate or higher intensity can raise VO₂ max enough to reduce mortality risk by 10–15% (Kodama, 2009). As always, the point is not the measurement itself, but the interventions and outcomes that follow.
If VO₂ max were a lab test, we would order it; if exercise were a drug, we would prescribe it. Although VO₂ max can be estimated from activity levels or step tests, direct measurement is far more precise, especially in people who are older, less conditioned, or returning to exercise after time away. NB: Don’t rely on your Apple Watch - it’s not accurate for VO₂ max.
Beyond the Scale: Why Body Composition Matters
Most people don’t lose muscle gradually. Instead, they experience stepwise drops, often after illness, injury, or hospitalization - and many never fully regain muscle mass or strength, accelerating age-related physical decline. The problem is that most people don’t even realize it’s happening, because their body weight hasn’t changed very much.
That’s where DEXA scanning is valuable. Unlike a bathroom scale, it separates fat from muscle and shows exactly where fat is stored. It quantifies total and regional fat, identifies visceral fat around the organs, measures muscle mass, and assesses bone density. Muscle and visceral fat can shift even when the scale stays the same. More importantly, DEXA scanning can help align your exercise and nutrition choices with the outcomes you want: building muscle, reducing visceral fat, or improving bone density.
Excess visceral fat, even in people who appear “normal weight,” drives metabolic dysfunction (Fox, 2007). The combination of high fat and low muscle - “sarcopenic obesity”- is especially common in adults over 60 years old and increases the risk of falls, frailty, disability, and cardiovascular disease (Batsis, 2018). Importantly, DEXA scans can reveal shifts in muscle and fat distribution that remain invisible on routine weight checks, providing patients with encouragement and clarity when tracking changes.
Those details matter because they determine whether you are simply lighter on the scale or genuinely stronger, healthier, and more resilient. If the scale told the whole story, we wouldn’t need DEXA scans - but healthy aging depends on what lies beneath. NB: Home scales that estimate body composition are not accurate enough to guide health decisions.
Why a Personal Trainer Beats Going It Alone
Exercise prescriptions look simple on paper, but in practice, most people struggle with consistency, technique, and progression. This is where a skilled trainer can be transformative. A good trainer provides accountability, teaches proper form, prevents injury (so you don’t go backwards), and helps translate abstract goals into practical, personalized plans.
The evidence supports this. Supervised training is consistently more effective than unsupervised exercise, particularly in older adults. Structured programs with coaching lead to greater gains in strength, balance, and functional capacity compared to exercising alone. Even short-term guidance can establish better habits, and ongoing coaching helps sustain them. Trainers also can adapt workouts during times of injury, illness, or travel, which are the very times people are most likely to regress.
The practical takeaway: a trainer is not an indulgence - they are a partner who ensures your effort translates into results.
Pulling It All Together
Step counts and generic exercise advice may keep us moving, but they rarely change outcomes on their own. VO₂ max testing shows us how fit we really are and helps guide an exercise prescription, DEXA scanning reveals what the scale can’t, and a skilled trainer helps turn effort into lasting progress. Together, these tools transform exercise from something vague into something personalized and actionable.
These are not luxury extras reserved for elite athletes. They are practical, underused tools that can benefit most people, especially those beginning to exercise after years of inactivity, recovering from illness or injury, or anyone who has hit a plateau and wants to train more effectively.
Of course, not everyone has access to these tools, and cost can be a barrier. But the larger point is this: they help, but the true benefit comes from the habits they reinforce - exercising smarter, preserving muscle, reducing harmful fat, and staying accountable. Once again, it is your actions that matter - not the measurements themselves.
References:
Kodama S, et al. Cardiorespiratory fitness as a quantitative predictor of all-cause mortality and cardiovascular events: a meta-analysis. JAMA 2009;301:2024.
Ross R, et al. Importance of assessing cardiorespiratory fitness in clinical practice: a case for fitness as a clinical vital sign. Circulation 2016;134:e653.
Batsis JA, et al. Sarcopenic obesity in older adults: aetiology, epidemiology and treatment strategies. Prog Cardiovasc Dis 2018;61:182.
Fox CS, et al. Abdominal visceral and subcutaneous adipose tissue compartments: association with metabolic risk factors in the Framingham Heart Study. Circulation 2007;116:39.
A few people asked me where to get testing and training. I highly recommend DexaFit Madison (https://www.madison.dexafit.com/) for V02 max stress testing and DEXA scanning. They are extremely professional and provide very high quality service; so high that my research lab uses their services for one of our major grants! For training, I highly recommend Ezra Miller (https://http://www.empowerfitnesspt.com/ - he especially excels at training middle- and older-aged people, building strength, and injury prevention. He is in Florida but provides wonderful remote services.
I can’t give medical advice about stress testing in your situation, but DEXA is meaningfully more accurate than BIA. They correlate, but agreement and reproducibility of most BIA systems not well enough to be useful. Ultimately, it depends on your goals - they will determine if the DEXA data would be useful and actionable for you. Since you’re already so attentive the gains might be less so - it depends on the specifics.