Muscle mass and strength correlate closely with health span and lifespan. This is supported by numerous studies of strength including grip strength, a marker for overall body strength, which show a close relationship to longevity. It also makes sense that our ability to maintain functions such as getting up off the floor, gardening, and traveling requires the coordination of well-functioning upper and lower body muscles.
The decline in muscle mass is associated with an increase in fat mass and a change in body composition that is linked to insulin resistance in older populations. These changes along with joint stiffness, kyphotic posture, and osteoporosis likely contribute to systemic inflammation and chronic diseases such as diabetes, heart disease, and cancer.
AGE and MUSCLE MASS
To efficiently optimize muscle mass and strength it is helpful to understand the evolution of our muscles across a lifespan and the exercise tactics that shape the evolution. Typically, humans are in a muscle-building phase through age 25. Between 25 and 35 years our overall muscle mass is stable. For most people, a slow decline of 3-8% per decade occurs between 35 and 75. The decline is accelerated during periods of chronic injury or illness if one is sedentary. After 75 years of age, there is a more precipitous change as most people experience a mutually reinforcing steep decline in muscle mass and physical activity. Also with age, we preferentially lose type 2 fast twitch muscle involved in power and speed and preserve type 1 slow twitch muscle that supports endurance.
EXERCISE APPROACH TO MAXIMIZE MUSCLE MASS
Resistance exercise with weights or bands is essential to optimize muscle size and function. Below are the concepts that support a successful program
PROGRESSIVE OVERLOAD VERSUS LOAD- is it better to lift light or heavy weights?
The key to building stronger, bigger muscles is progressive overload, gradually increasing the stress placed on a muscle by increasing mechanical load (weight) or volume (the number of repetitions within a set or the total number of sets). Bodies are adaptive entities. When we expose our bodies to small incremental changes in acute stress followed by recovery, they remodel to handle that stress. The progressive overload concept is the key. A person can train with light or heavy weights and build muscle size and power if they challenge their muscles. For athletes focused on achieving a 1 repetition maximum in a single lift there may be a strength-related advantage in that particular exercise with heavy load training. This benefit dissipates when the strength testing is conducted on a different modality from the one that was used in training. For example, testing on an isometric device in someone training with barbells.
In regards to hypertrophy, a 2017 meta-analysis of 21 studies showed there is no difference in gains in muscle size with light versus heavy loads.
As we age, it may be advantageous to shift toward low and medium loads to avoid injury. Consistent exercise is a cornerstone of healthy aging in part because older muscles atrophy at a faster rate during sedentary periods.
REPETITIONS PER SET-how many repetitions should I include in each set if I am trying to build muscle size, muscle strength, or endurance?
The historical description of repetition ranges suggests that 1-5 is the strength zone, 8- 12 is the hypertrophy (maximum muscle building) zone and >15 is the endurance zone. Recent data shows that muscle strength will increase in all 3 zones and similar gains in muscle size are achieved with up to 30 repetitions per set.
To improve strength, 3-5 sets (assuming 8-12 repetitions per set) per week is equally effective as a higher training volume of 10-15 sets per week. This approach is more time-efficient and results in greater adherence. Of note, some studies show increasing gains in muscle size with up to 30 sets per muscle group per week.
WORKOUT INTENSITY- should I exercise to point of muscle failure?
While working your muscles to failure will create slightly more muscle hypertrophy it will also require considerably more recovery time (related to delayed onset muscle soreness) and possibly a higher risk of injury. When doing sets of resistance exercises it is reasonable to stop when you are 2-3 repetitions short of your maximum effort. For example, if you can do sets of 20 pushups, stop at 17. When 17 pushups become easier, you can add additional repetitions. Particularly with lower loads, training with a high level of effort is essential for achieving increases in muscle mass.
COMBINING CARDIO AND RESISTANCE TRAINING- should I do my weights before my cardio? Will my cardio training undermine my resistance training?
Moderate amounts of cardio exercise (30-45 mins per day) will not impede your ability to gain muscle mass. If combining resistance and cardio in a single workout it may be best to start with resistance to ensure that you commit a high level of energy to your resistance session. Better options include separating your cardio and resistance sessions into morning and afternoon workouts or alternate-day workouts. Of note, the two types of cardio workouts that promote gains in muscle size are biking and high-intensity running intervals.
GENDER DIFFERENCES IN TRAINING: Do men and women benefit from different types of training?
There is limited data to explain the sex-related difference in neuromuscular performance. One study has noted that women are more resistant to fatigue. This may have implications for training regimens and recovery intervals.
CONCLUSIONS:
STRENGTH: Lifting heavier versus lighter loads will increase the ability to perform the exercise that is trained. Lifting heavier versus lighter loads will not provide significant changes in strength when testing is carried out on a different modality such as training with free weights and testing the same muscles on an isometric device.
MUSCLE SIZE: Lifting with heavier or lighter weights and lower or higher repetitions will achieve similar gains in muscle mass.
WORKOUT RECOMMENDATIONS
- WORKOUT FREQUENCY and DURATION: Aim for two resistance sessions per week lasting 30 -60 minutes per session. Younger exercisers seeking increased muscle size will favor longer sessions.
- NUMBER OF SETS PER MUSCLE GROUP PER WK: 4 sets per muscle group per week for strength and 6-10 sets per muscle group per week to optimize muscle size.
- REPETITIONS PER SET: 8-12 repetitions per set to achieve balanced gains in muscle size and strength.
- WORKOUT INTENSITY: Moderate intensity. Aim for 2-3 repetitions short of failure to achieve significant gains in mass and strength with a lower risk of injury.
Bradford Rabin MD is a concierge medicine doctor caring for patients in the San Francisco Bay Area including Palo Alto, Menlo Park, Los Altos, Portola Valley, and Woodside.