Fitness Articles

Reference Guide to Strength Training

An In-Depth Look

Page 2 of 4

4 Principles of Strength Training
The four principles of strength training are guidelines that will help you strength train safely and effectively to reach your goals.

1. The Tension Principle: The key to developing strength is creating tension within a muscle (or group of muscles). Tension is created by resistance. Resistance can come from weights (like dumbbells), specially-designed strength training machines, resistance bands, or the weight of your own body. There are three methods of resistance:
  • Calisthenics (your own body weight): You can use the weight of your own body to develop muscle, but using body weight alone is less effective for developing larger muscles and greater strength. However, calisthenics adequately improve general muscular fitness and are sufficient to improve muscle tone and maintain one’s current level of muscular strength. Examples include: pushups, crunches, dips, pull ups, lunges, and squats, just to name a few.
  • Fixed Resistance: This method of resistance provides a constant amount of resistance throughout the full range of motion (ROM) of a strength training exercise. This means that the amount of resistance/weight you are lifting does not change during the movement. For example, during a 10-pound curl, you are lifting 10 pounds throughout the motion. Fixed resistance helps to strengthen all the major muscle groups in the body. Examples include: Exercises that use dumbbells (free weights), resistance bands and tubes, and some machines.
  • Variable Resistance: During exercises with variable resistance, the amount of resistance changes as you move through the range of motion. This creates a more consistent effort of exertion throughout the entire exercise. For example, when lifting weights, it is harder to lift up against gravity and easier to lower the weight down with gravity. Specially-designed machines (like Nautilus and Hammer Strength brands) take the angle, movement, and gravity into account so that the release of a biceps curl feels just as hard as the lifting phase of the curl.
2. The Overload Principle: In order to build strength, your muscles must work harder than they are accustomed to. This “overload” will result in increased strength as the body adapts to the stress placed upon it. Everyone begins at a certain level of strength. To become stronger, you must regularly increase the tension (weight or resistance) that your muscles work against, causing them to adapt to a new level. As the muscles respond to an overload, they will grow in size and strength. There are two types of strength overloads:
  • Isometric means “same length.” This is a high-intensity contraction of the muscle with no change in the length of the muscle. In other words, your muscles are working hard but the muscle itself remains static. Isometric exercises are good for variety and some strength maintenance, but they don’t challenge your body enough to build much strength. Learn more about isometric exercise here.
  • Isotonic means “same tension.” When you lift weights or use resistance bands, your muscles are shortening and lengthening against the resistance. This challenges your muscles throughout the entire range of motion. However, the amount of force the muscle generates will change throughout the movement (Force is greater at full contraction/shortening of the muscle). Unlike isometric exercises, this type of contraction does help build strength. Continued ›
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About The Author

Jen Mueller Jen Mueller
Jen received her master's degree in health promotion and education from the University of Cincinnati. A mom and avid marathon runner, she is an ACE-certified personal trainer, health coach, medical exercise specialist and behavior change specialist. See all of Jen's articles.

Member Comments

  • Very helpful. - 2/27/2016 7:38:24 PM
  • i needed to read this!! - 6/15/2014 10:11:00 PM
  • Lots of information here. Thanks. - 5/3/2014 6:23:46 AM
  • I also have to take issue with this concept of HAVING to take a rest day. Do you think MINERS or FARMERS or anyone else that has a physical component to their WORK has the luxury of taking a DAY OFF you are kidding yourself. - 1/26/2014 5:55:07 PM
  • This article is exactly what I have needed! Thank you - 1/25/2014 10:37:41 AM
  • I learned a lot by reading this. I do want to get stronger so it gave me fuel to use to do this. so with workout at home and weight lifting class I can get stronger and see more muscles......I like that. - 1/20/2014 8:00:34 PM
  • I totally disagree with the statement that fewer reps builds stronger muscles. All that matters is that you work the muscle to failure NOT how many time you do a particular exercise,.If that were the case bodyweight exercisers would be hooped. - 12/28/2013 9:47:23 PM
  • I disagree with the statement that strength training strengthens tendons and ligaments. I'd like to see where this has been proven. I have Ehlers Danlos so my tendons and ligaments (and other connective tissue) are too loose, causing my joints to dislocate frequently. Exercising, even gentle and no impact, causes more problems with my joints, not less. I have to pay close attention to everything I do because even one uncontrolled movement causes pain and dislocations. When I was in sports as a kid my joints actually became much worse, not better. Now my hips can dislocate just from walking. Thus my tendons and ligaments became weaker - not stronger - through exercise. If the Ehlers Danlos was diagnosed as a kid I would have been told to exercise less, not be in sports, and I would have had access to doctors who could provide proper braces for my joints well before my joints got to be this bad.

    There are also many cases of people who have torn tendons and ligaments through exercise (ever seen an achilles tendon snap while someone's running?). They're not being strengthened, but being tested and pulled. - 7/15/2012 4:31:51 AM
  • I think this article makes a lot of really good points, and I'm really glad that the "Specificity of Training" principle was included - I just wish the SparkPeople Training Plan Generator would get the message. Since it's well documented that doing a leg day back to back with an arm day is totally fine since you're targetting complete different muscles, it's so *frustrating* that the workout generator *won't let you* enter back to back workouts on different mucles groups, reminding you that you shouldn't train back to back without a rest day (perfectly true, if you're using the same muscles). I realize that this is the wrong place to vent about this, and I've already raised it in the "tech" forum, but it seems I can't help myself - BAH!

    In any case, I was happy to see this idea, and others that are equally important, explained here clearly and accurately. Bravo. - 12/13/2011 11:08:35 AM
  • Don't forget that water exercise, especially vertical exercise like water aerobics, has a strength component. Water resistance is 12x the resistance of air, so every move in every direction is evenly resisted. To add challenge similar to adding weight to dumbells, you can use various devices to increase buoyancy or drag resistance. You can employ speed, acceleration, and direction change to further up the ante. AND there's no danger of dropping a chunk of iron on your toe! - 12/13/2010 1:11:15 PM
  • I have been strength training since 1987. I had a trainer for a couple years. After becoming comfortable at one weight, I increase it just like you're supposed to do. I mostly do machine exercises, but also bicep curls--free weights. However, a few years ago, I was getting strange sensations in my right thigh, sort of like when your arm or hand "go to sleep" and you experience tingling in it. I had that sensation in my right thigh. I went to physical therapy, and now I have specialized stretches to do every day. My thigh has much improved. However, I was told not to do the abductor or adductor machine exercises since they are not at all helpful, and as I remember they are not highly recommended in the Fitness section of SP. I was also doing the back stretch machine, which to me was like rocking and it was even fun. I had worked my way up to putting all the weight blocks on, including even extra weight--over 300 pounds--and I was quite proud of myself, to be able to lift more weight than many of the men. But the physical therapist was very critical of this, saying I would definitely be popping a disk if I continued doing that. She said that someone my age, 63 then, could not do exercises like they could at a younger age. She also nixed the leg pushes I was doing and said I should not be going over 150 lbs. (I was lifting about 100 lbs. more.) So I pass this information on if it can be of use to anyone. And if Jen wants to comment on this or give me some advice, I'd appreciate it, since I want to be sure that what I'm doing is all right. - 12/13/2010 1:00:15 PM
  • I've just started strength training in my pulmonary rehab program and I really excited. I used three different machines yesterday for 10 reps each. Can't wait to get more familiar with the system! - 10/9/2010 1:54:26 PM
  • very good info for the novice! thanks a lot - 10/9/2010 1:47:28 PM
  • It says I read the article in March, but i don't remember reading it before. I enjoyed it and feel that I am still a beginner. At my age, I may never progress any farther.!
    Very informative. - 10/9/2010 11:23:15 AM
  • Great article! I'm reading a lot about strength training and working out with a small weight-lifting class. Up til now, that part of the gym was a black box to me. I ignored it.

    Weight-lifting is fantastic. It makes my gym workouts far more interesting because I mix it up every day. I appreciate and learn from other gym members--many of those exercises are a LOT harder than they look, I had no idea. My body is sculpting as I'm losing weight. At 5'6" and 214 lbs, I'm obese. But I'm a lot stronger than the skinny girls taking the weight training with me. Yay! - 3/3/2010 10:54:57 AM

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