Beyond mere aesthetics, strength training plays a prominent role in leading a healthier, longer, and more active life. It's not just about looking strong on the outside; it's about being strong, both inside and out. Studies show that strength training is one of the most effective ways to strengthen healthspan, the number of years in your life marked by vitality and good health. Strength training even a few times a week allows you to reap benefits related to bone health, metabolism, heart health, cognition, and even lifespan itself. 
It’s well-established that exercise is critical for health and healthspan, yet over 60% of US adults do not get enough strength-based exercise, marked at two sessions per week. [3,4] To live your best life in the later decades, you need to prioritize building strength and muscle today. What you do for your body in your 30s, 40s, and 50s sets the stage for how your body will perform in the decades ahead. So, let's explore how strength-based training can unlock a healthier longer life.
What is strength training?
Strength training, also known as resistance training, is a form of exercise that uses resistance to build muscle. Resistance comes in many forms, like resistance bands, free weights, weight machines, household objects, and even your own body weight. By progressively adding more resistance, muscles can adapt and take on more weight as they build stronger over time. 
How strength training builds muscle mass
Strength training builds muscle mass by causing small microscopic tears in the muscle fibers. The body then repairs these tears by fusing new protein strands into the muscles, increasing muscle mass and ability to generate more force. This process is called muscle protein synthesis. 
What determines your ability to maintain and build strength?
Your ability to build and maintain strength depends on the interplay between your genetics, lifestyle, and environment. Genetics can influence susceptibility to certain health outcomes, while lifestyle choices can significantly impact the health outcome itself.
Here are two examples of genetic insights InsideTracker provides that can be modified by lifestyle:
- Age-related muscle weakness refers to the tendency to lose muscle strength in old age. Weaker muscles are less able to support activities of daily living, physical activity, and balance, making muscle weakness a strong predictor of poor health outcomes and aging. In fact, while muscle mass and muscle strength generally go hand-in-hand, studies show that the latter might be a better independent predictor of health aging.  Muscle weakness results from genetics and lifestyle factors like nutrition and exercise. Engaging in resistance training is one way to leverage lifestyle habits to overcome a genetic predisposition for muscle weakness. 
- Bone mineral density (BMD) measures the mineral content of bones. A higher bone mineral density is indicative of bone strength. Genetics can determine whether you possess a risk of having lower bone density. But it’s your lifestyle factors, like resistance training, that can help influence your actual bone mineral density. 
Strength training and lifespanThere are many health benefits of participating in strength training, and it turns out strength training can also lengthen the lifespan (the number of years in life). In a meta-analysis of 16 studies and data from over 1.5 million subjects, muscle-strengthening activities were associated with nearly a 10-17% lower risk of cardiovascular disease, cancer, diabetes, lung cancer, and all-cause mortality.  The study observed a J-shaped association between muscle-strengthening activities and disease risk-reduction, with a maximum risk reduction observed at 30-60 minutes of resistance training per week. While more research is required to better understand the dose-response relationship, there are clear healthspan-related benefits of resistance training at relatively low durations.
Building muscle, bone strength, and endurance through strength training
By building lean muscle mass through regular strength training, you can help maintain mobility, independence, and healthspan well into old age. Here’s a look at how strength training benefits muscle strength, bone health, and endurance.
Muscle health and strength
Age-related loss of muscle mass and strength, known as sarcopenia, can begin as early as age 40. And with each passing decade, you can expect to lose 3-8% of muscle mass if you don’t counteract it.  To put this into perspective, you can lose up to 50% of your muscle mass by your 80s due to inactivity. 
Strength training is effective at combating sarcopenia through muscle repair and regeneration, and can help prevent muscle loss while adding new lean muscle tissue. Consistent strength training is key to keeping muscles strong into your later years. [6,9]
Resistance training can improve other aspects of health in addition to combatting sarcopenia. The exercise can improve hand grip strength in older adults, a proxy for full-body strength, that has longevity benefits.  And in one randomized controlled trial, adults over the age of 65 who engaged in resistance training, including squatting, were able to increase lower limb strength and better maintain balance. 
Throughout aging, bone mineral density tends to decline. This is partly due to hormonal shifts experienced in aging, and at a population level, also due to an increasingly inactive older population. It’s so common that it now has a term to describe it: osteoporosis—a disease that occurs when bone mineral density and bone strength decline. In one semi-randomized controlled trial, when men with low bone mineral density at baseline participated in resistance training twice a week, they were able to improve their bone strength.  While the condition affects both men and women, females experience osteoporosis at over four times the rate of men, making it critically important for women to take preventative action. 
Strength training isn't solely about building muscle. Studies show that resistance training can significantly improve measures of endurance, making it a valuable addition to any fitness routine.
For younger adults, strength training can lead to notable increases in VO2max, a key indicator of endurance, with one study reporting improvements ranging from 3.5-13.6%. Older adults can also reap the benefits, as resistance training has been shown to enhance cardiorespiratory fitness. Whether the goal is to hike in your later years or to simply keep up with daily activities, strength training can boost your ability to actively participate in many aspects of life. [13,14]
Metabolic benefits of strength training
Metabolism encompasses the chemical processes that provide the body with energy, and metabolic benefits can also result from strength training. Incorporating resistance training into your fitness routine improves body composition measures and reduces the risk of metabolic syndrome, a precursor to type 2 diabetes.
Strength training can improve measures of body composition like fat mass and waist circumference, which are associated with several poor health outcomes. In one randomized controlled trial, sedentary adults that began resistance training significantly reduced their waist circumference in as little as eight weeks. 
As women age, hormonal shifts can make weight and fat loss challenging, but resistance training can assist. Postmenopausal women who resistance trained saw a 10% improvement in body fat percentage compared to baseline, according to one trial. 
Metabolic syndrome and type 2 diabetes
Building muscle mass through strength training is also critically important for blood sugar control. Properly managing blood sugar is a cornerstone of preventing metabolic syndrome, and muscle plays a notable role; some experts describe muscle as a “metabolic sink” for blood glucose disposal.
A meta-analysis in Diabetes Care found that all forms of exercise improved measures of blood sugar control significantly. In fact, the researchers found that the effects of exercise were similar to those of dietary, drug, and insulin treatments in managing blood sugar of participants with type 2 diabetes. 
And while aerobic exercise alone can improve metabolic syndrome, combining resistance and aerobic training appears to be even more effective. These paired exercises have also been shown to improve triglycerides and blood glucose levels. 
Strength training can reduce the risk of the leading cause of death: heart disease
In the United States, someone has a heart attack every 40 seconds.  In fact, heart disease is the leading cause of death in both men and women in the US. The troubling fact is that heart disease has been the leading cause of death for over a century—meaning current strategies haven’t been effective in preventing and treating heart disease at the population level. 
The good news? Studies conclusively show that strength training effectively improves the cardiovascular profile.
The heart is a muscle that performs best when trained. Numerous studies have highlighted strength training's potential to lower the risk factors associated with heart disease in both men and women, contributing to a healthier cardiovascular profile. A randomized controlled trial of 69 adults found that as little as eight weeks of resistance training reduced risk factors associated with heart disease. Many other studies show that strength training is effective in lowering elevated blood cholesterol levels, which are known to impact heart health. 
Research has shown that engaging in regular strength training sessions can effectively lower inflammation levels in the body, particularly high-sensitivity C-reactive protein (hsCRP). One study found that strength training significantly reduced hsCRP levels by 11 and 39% at 16 and 32 weeks compared to baseline. Reductions in hsCRP were also associated with improvements in strength and fat loss. 
These reductions in inflammation are closely associated with improvements in both cardiovascular health and overall well-being. By incorporating strength training into your fitness routine, you can strengthen muscles including your cardiac muscles—a crucial factor in reducing the risk of heart disease.
Cognitive benefits of strength training
Strength training is not only beneficial for the body but also the mind. In fact, studies show that strength training elicits cognitive benefits both immediately and over the long term.
Mood and depressive symptoms
The benefits of strength training may manifest differently from person to person. At the group level, studies have shown that resistance training can improve mood and symptoms of cognitive disorders like depression and anxiety. A meta-analysis found that resistance training could improve the quality of life and depressive symptoms in older adults.  Studies on the impact of strength training on other populations that range in sex and age show similar results.
Reduced risk of cognitive decline
Strength training can also have cognitive implications realized in later decades. Cognitive abilities like learning, memory, and reaction time can start to slip over the years, but lifestyle factors like resistance training can promote mental sharpness as aging progresses In one meta-analysis of those over the age of 50, participating in 45-60 minutes of moderate-intensity resistance training sessions was associated with a significantly improved cognitive function compared to those who didn’t exercise at all.  And it turns out that pairing resistance training with mental tasks may produce better results. A study on older adults found that simultaneously performing mental tasks and resistance training was more effective at improving working memory than without resistance training. 
Strength training is more than just a means to build muscle; it is a holistic approach to enhancing healthspan and extending one's overall lifespan. Conclusive research shows that strength training positively impacts muscle and bone health, body composition, metabolism, heart health, cognition, lifespan, and more. While you may have genetic propensity to age-related muscle weakness or low bone mineral density, lifestyle habits like resistance training can mediate that risk. Including strength-based exercises in your regimen, even a couple times a week, can be a pivotal step towards a healthier longer life.