There are two major benefits that require challenging weights
Strength.
Gaining strength is the most fundamental benefit of strength training. Strength, though, is largely dependent on how much you lift. Lifting heavier weights is substantially more effective for building strength. This change can’t be made up for by performing extra sets. Strength is a benefit that can only be maximized through the use of challenging weight loads.
Bone Density.
Strength training is also known for its ability to strengthen bones. This benefit is only fully realized when challenging weight loads are used. In fact, light weight training has a minimal impact on bone strength.
Two of the most important and generally desired benefits of strength training are only fully obtained through the use of challenging weights. As you can see, lifting a challenging weight load is important.
Lifting with Light Weights
When we’re able to choose for ourselves, we tend to use weights that are too light. We underestimate what the “right” weight load is. This makes sense because light weights are comfortable and challenging weights are uncomfortable. And lifting light weights is better than lifting no weights at all.
So, why strain if we don’t have to?
Aside from being comfortable, another common reason people gravitate towards lifting lighter weights is because we tend to associate “challenging” with “dangerous.” Lifting challenging weights is not the cause of injuries.
In fact, exercise injuries generally occur with free weight accidents (i.e. dropping the weights), broken equipment, or with high impact activities (jumping, aerobics classes, etc.). You won’t face those issues with me as a trainer if you were wondering…
Also, the amount of weight you lift matters. No amount of lifting light weights adds up to the value of lifting challenging weights.
People often push back on weight increases, even when getting stronger. This is one area where a personal trainer is important. Trainers understand what an effective weight load is and will choose that weight load, even if it makes the trainee a little uncomfortable at the start of the exercise. They know when the member has gotten stronger or is too strong for the previous weight load. Trainers also know why challenging weight loads are important.
What Does a “Challenging” Weight Mean?
“Challenging” can be tough to define, especially when every exercise results in muscle failure (the inability to lift the weight again). Muscle failure can happen with heavy or light weights. Light weights simply require more time to reach that end point.
Here are two ways that you can gauge if your weight load is heavy enough:
Rate the difficulty on the first repetition.
An ideal weight load should present some challenge on the first rep. During the first rep, rate the difficulty on a scale of 1-10 (1 = “I can do this all day” and 10 = “This is impossible”). The ideal weight should fall in the 6-8 range on the first rep.
You reach muscle failure within 60-90 seconds.
This is a better indicator of how to determine if the weight choice is correct. If you reach muscle failure within 60-90 seconds, the weight is the perfect balance between light enough to allow for proper form while being heavy enough to improve strength and bone density.
Summary: Lifting Heavy Weights vs. Light Weights
If you prefer strength training with weights that are “easy” or “comfortable,” you are like most people. Push past that initial reaction and embrace more challenging weight loads! Light weights won’t lead to achieving all of the benefits that strength training can provide. Specifically, if you want to maximize your strength and bone density, use weights that are moderately difficult from the start of the set. If you can leg press 80kg , leg press 80 kg – not 60 kg.
Your weight should lead you to achieve muscle failure in the 60-90-second time range.