Science Behind Strength and Endurance Training
Goals
Before we get into the science behind training we have to talk about goals. Goals are one of the most important parts of training. What do you want to accomplish? Do you want to be stronger? do you want more endurance? do you want to loose weight? Are you trying to learn a new skill?
Whatever your goal is focus on that. If it is a general or difficult goal to attain structure your program to be a road map towards that goal. Smaller attainable goals along the way will not only keep you motivated, but will allow you to objectively track your progress.
Science behind Training
To truly understand what you are trying to accomplish with training you need to understand the science behind it. Here is a simplified explanation of some of the key components.
Anaerobic vs. Aerobic
The Anaerobic system
This system functions without oxygen and results in a large output of energy. The problem is it isn’t sustainable and results in lactic acid build up in the muscles. Think of this system as the fuel source for those taking part in sports that require short burst of energy such as sprinting.
Aerobic System
This system functions with oxygen but does not provide as much energy. This is system is used for low intensity exercises but will not result in a build up of lactic acid meaning that you can continue to use this energy source for long periods of time. This system is utilized more in long distance athletes.
We must realize that these systems work together. generally in day to day activities our aerobic system is paramount, however if we decide to go for a work out or climb or run we will require more energy. If we hit the Anaerobic threshold the anaerobic system kicks in to supply the remainder of the energy demanded of the activity.
Muscle fibers
There are 3 different types of muscle fibers. The type of fibers recruited for the activity will depend on its intensity. Therefore your training intensity dictates which muscle fibers you are stimulating and which will adapt to meet the activities demand.
Slow twitch (ST) fibers: ST fibers are particularly good at processing oxygen and therefore use primarily the aerobic system. ST fibers characteristics include high capiliarization (more blood vessels = more oxygen supply), high density of mitochondria (the powerhouse of the cell) and have a small diameter (less contractile force). These fibers are recruited for low to moderate intensity activities that can be sustained for long periods of time.
Fatigue - Resistant Fast Twitch Type IIB (FTa): FTa fibers compared to ST fibers are larger in diameter (approximately 5x the contractile force) and have lower mitochondrial density. These fibers are recruited as the intensity of the activity rises. and are generally used in long term anaerobic activities. This means during the activity you have hit the anaerobic threshold but you are not at 100% exertion. These fibers are extremely important in training as they are a in between fiber that can be trained to more closely resemble the fibers on either side of the spectrum.
Fast Twitch Type IIB (FT): FT fibers are our strongest fibers with the largest diameter. they are activated when taking part in activities that are reaching our maximal strength. These fibers use the anaerobic system and are easily fatigued, generally in under 1 minute of activity. These fibers are only activated when nearing maximum effort, thus a strong neuromuscular connection must be present to train theses fibers.
Let's look at two of the most common goals in training increasing strength and increasing endurance and how we can apply what we have discussed above.
Increase Strength
If increasing strength is your goal you must assess your starting point and work your way up. Beginner vs. Advanced strength training blog post is a good place to find more information on this.
After you have established your starting point you need to determine what your goal requires.
Is it pure anaerobic strength you're looking for that is only required in short bursts (Fast Twitch Type IIB muscle fibers)?
Is it anaerobic strength that you must maintain for over a minute (Fast Twitch Type IIA muscle fibers)?
do you only need moderate strength over a long period of time where you would be training a mix of aerobic and anaerobic systems (Slow Twitch and Fast Twitch Type IIA muscle fibers)?
All of these factors will play a roll in structuring your training program. Generally speaking a strength specific program will have a focus on Fast twitch fiber (IIA and IIB) and working primarily with the anaerobic system. This is done by spending time maximizing contraction with ample rest between sets to allow recovery.
After you have determined your starting point and your goal your program should be structured to fit that goal. There are a few key things to keep in mind that hold true for most strength programs.
It takes an average of 6 weeks to accomplish strength gains through muscle development, so consistency will be key. Your programs should always be longer than 6 weeks if this is your goal.
If you are not challenged you are not changing. Once you have ramped up to a point in your training that your strength gains are coming from muscle development you should be pushing yourself. if you are doing traditional exercises you should be shooting for 6-8 reps before failure. Remember training is introducing stress to the targeted body segment and allowing the body to adapt to that stress. At this point you need to change or increase the stress in a step wise progression to continue seeing results.
Get a good sleep. The importance of sleep can be seen in our past blog post Why do we sleep?. Sleep is incredibly important in recovery one of the main benefit we see that is linked to training is the increase in growth hormone when we sleep. This increase is very important when you are trying to build muscle.
Protein is the building blocks of muscle. If you are training to increase strength you are making micro tears in the muscle. if you do not have adequate calories through nutrition and most importantly adequate protein you will be taking protein from other parts of your body. You don’t want to build a deck by taking wood from your house.
Water. Hydration is important in any form of training. you will not be able to perform or challenge yourself unless your muscles are adequately hydrated.
Increase Endurance
Generally speaking programs aimed to increase endurance will focus on slow twitch and fast twitch type IIA muscle fibers.
If increasing endurance is your goal you will be working to increase your anaerobic threshold. Spending long amounts of time under lower exertion and progressively longer times at moderate exertion will stimulate the body to adapt. Adaptation happens by increasing capillaries and blood flow to the area (increase oxygen), increased amounts of mitochondria, and increasing aerobic enzymes (allows more efficient aerobic system). This will allow the body to perform at a higher intensity of activity before transitioning to an anaerobic biased system, therefore you will be more resistant to fatigue.
The same rules will apply to endurance training as far as rest, nutrition and hydration, but how you structure your program will change.
You will be focused on challenging your time of exertion rather than your max power. If you are in the gym you will be using lighter weight with increased repetitions aiming for 12-15 repetitions. cardiovascular exercises will become very important as you move forward in an endurance program. You are adapting your body to become very efficient by increasing capillary density (increasing blood flow, mitochondrial density and aerobic enzymes. Your training goals will largely dictate the time and or distances you will have in your program. For example a marathon runner will train differently for endurance than a big wall climber even though endurance is required for both activities.
We are what we continually do
At the end of the day this is what it boils down to. someone that spends there time running marathons is not going to be the best power lifter and vice versa. This is why it is so important to have a goal in mind. To get the best results for your effort make a program that make sense with your goals, be consistent with your training and nutrition, allow yourself adequate rest and you will see the benefits.
References
Skinner JS, Mclellan TH. The Transition from Aerobic to Anaerobic Metabolism. Research Quarterly for Exercise and Sport. 1980 Mar 1;51(1):234–48.
Cunningham D, Faulkner J. The effect of training on aerobic and anaerobic metabolism during a short exhaustive run. Medicine and Science in Sports. 1969 Jun 1;1(2):65–9.
Howald H, Hoppeler H, Claassen H, Mathieu O, Straub R. Influences of endurance training on the ultrastructural composition of the different muscle fiber types in humans. Pflugers Arch. 1985 Apr 1;403(4):369–76.