Resistance Training for the Lower Body

"I'm a runner...that's all I do for my legs."

"I use the Elliptical machine and I can feel it working my legs."

When I recommend lower body resistance training to my clients, I am often met with responses like those listed above. There seems to be a lack of understanding that cardiovascular exercise (i.e. running, Elliptical) and resistance training have very different purposes and effects on the body. This post defines and provides background information on cardiovascular exercise and resistance training. It then explores four important reasons to include lower body resistance exercises in your program.

Cardiovascular endurance exercise, what most gym-goers refer to as simply "cardio," is any strenuous activity requiring the body's large muscle groups for a prolonged period of time. There are many benefits of cardio but the main function is to improve the heart's ability to deliver oxygen to the working muscles and for the muscles to become more efficient at generating energy with that oxygen. The muscular adaptations that occur in response to cardio are to the extent that they help the heart and vascular system deliver and use available oxygen.

Resistance training, what we more commonly think of as weight training, involves using external resistance to improve muscular strength and/or muscular endurance at a particular muscle or group of muscles.

Muscular strength is the ability of a muscle to produce maximal force. To improve muscular strength, one would train using weights that fatigue a muscle in 4-8 repetitions.

Muscular endurance is the ability of a muscle to generate a submaximal force over a given period of time or for a given number of repetitions. To improve muscular endurance, one would train using weights that fatigue a muscle in 12-15 repetitions. *Note the difference between muscular and cardiovascular endurance training: Muscular endurance training fatigues a muscle, or group of muscles, in 12-15 repetitions; cardiovascular endurance training allows for thousands of repetitions in a group of muscles.

The benefits of resistance training not associated with cardiovascular exercise include:

- Muscular hypertrophy (aka increase in muscle size): Hypertrophy is usually associated with resistance training in the 8-12 repetition range and employing at least 4 sets for each muscle. Performing only cardiovascular exercise will not lead to an increase in muscle size for the legs. This is important to consider for those looking to improve body composition by increasing overall muscle mass. While muscular hypertrophy in the upper body muscles may be aesthetically appealing, the majority of our lean muscle is concentrated in the quadriceps, hamstrings, and gluteal muscles of the lower body.

- Enhanced strength of connective tissue: As muscles adapt to the stimulus provided by resistance training, so do the connective tissues - tendons, ligaments, and cartilage - around them. Unlike running which tends to aggravate and lead to deterioration of connective tissue in the knee especially, resistance training provides a stimulus to the structures at this joint so they adapt and grow stronger.

- Preventing Osteoporosis: Unlike cardiovascular exercise, resistance training provides enough force to the bones to generate an increase in bone mineral density. Put another way, running and lifting weights for your upper body only will not prevent osteoporosis in the bones of the lower body.

- Increased circulation of anabolic hormones: Anabolic hormones like testosterone (ladies, we have this too) and growth hormone help synthesize muscle tissue from the proteins we eat. Resistance training, unlike cardiovascular exercise, causes a significant increase of anabolic hormones in the bloodstream. This response is even greater when lower body exercises are included. So what? In one Denmark study, scientists measured the arm strength of a group of subjects and then divided them into two groups. One group trained only with arm exercises (A group) while the other trained their arms and legs (AL group). Both groups spent the same amount of time training their arms, but the AL group also performed leg exercises as part of their resistance training program. At the end of the experiment, the A group had increased their arm strength by 9%, while the AL group had improved their arm strength by 37%! By recruiting large muscle groups through resistance training, the AL group stimulated a massive response of anabolic steroids which led to greater gains in their upper bodies.