In my first guest post I introduced the topic of cross training; specifically that sport participation shouldn’t be the entirety of your fitness regimen. This post will further explain how the body adapts to training and why systematic training is necessary for performance.

Ironically titled Resistance Training 101, the science behind different types of training is far from simple. Brass tax: Changing the amount of weight used and the number of reps performed will elicit a different adaptation from your body. These changes happen on a cellular and neurological level. Just as we hire trained professionals to help us with so many aspects of our lives, so too it is a good idea for how we spend our fitness time. Read more to find out why.

There are three types of muscle fibers, Type I (Slow Twitch), Type IIa (Fast Twitch), and Type IIx (Fast Twitch). Type I are the fibers that are most resistant to fatigue. They get used at all intensities of activity, but don’t have the ability to generate a lot of force. Type IIa fibers are an intermediate step between Type I and Type IIx. Depending on your training goal and the type of training you are doing these fibers can be higher force or more resistant to fatigue. These fibers are utilized at intensities that are too high for Type I alone. Type IIx fibers have the best ability to generate force, but they tire quickly. Type IIx fibers are only recruited at high intensities.

Recruitment refers to how many muscle fibers are being utilized during an exercise, and this is where some of the most sophisticated science comes in:

With high weight and plyometric style training you can lower the threshold that has to be met before your Type IIx fibers are recruited. This means that your existing muscle will have more strength, without changing the size or weight of the muscles. This is simply from improving the communication between the nervous system and muscles so that a higher percentage of fibers are recruited. This should be a big goal for cyclists, or anybody else that needs a high power to weight ratio. This is one of the biggest reasons to do strength or power training, even for endurance sports. Strength gains are made when reps are kept below 8 and the resistance is above 80% of your 1 rep max.

But what about mass or endurance gains? Mass gain is the result of increasing the number of contracting fibers in your muscle cells. This change is elicited by doing multiple sets with about 8 to 12 reps, at 70 to 80% of your one rep max. Endurance gains are made from increasing the number of mitochondria in a muscle cell and the concentration of aerobic enzymes to fuel activity without producing lactate. These changes are generally produced with multiple sets and at least 15 reps, at or below 65% of your one rep max. Opinions may vary on exact rep numbers, but the premise of low reps for strength or power, mid-range reps for mass gain, and high reps for endurance holds true. A resistance training program makes it much easier to elicit the necessary changes to reach your goals.

One of the other big problems posed when you just do a sport activity is that it probably doesn’t work all muscle groups equally. A big reason for this unequal distribution of work is that the majority of our movements are in the sagittal plane, going forward or backwards. To fix these imbalances, we need to do different movements to work the neglected muscles. This is why we do lateral and rotational movements. They help fix stabilizer weaknesses before they become injuries.

When you look at the ability of resistance training to effectively stimulate a specific adaptation in muscles, and to fix imbalances, it’s clear that everybody can benefit from proper resistance training.