The Truth About Heavy Weights

One of the most misunderstood aspects of resistance exercise is the role of load (weight). As practitioners, it is common to hear a client raise concern over a weight that is “too heavy.” When this issue arises it is typically for two reasons. 1) They assume that a heavier weight puts them at a higher risk for injury. 2) They believe that a heavier weight elicits bigger, bulkier muscles. A simple YouTube search will provide a convincing confirmation bias to both of these assertions, but when we examine the peer reviewed research on this topic we see essentially the opposite conclusion.

Using a heavier load typically requires a higher level of effort from the exerciser, and this added effort stimulates a number of physiological processes (increased breathing rate, increased heart rate, increased physical demand from skeletal and musculoskeletal system, increased blood pressure). For novice lifters, this can be very intimidating and even fear inducing. In turn, they tend to shy away from heavier loads assuming that the increased physiological demand is putting them at risk for injury–but there’s so much more to consider. All too often when we lift weights we pay little or no attention to the speed of movement and rather are just concerned with achieving an arbitrary number of repetitions. This in turn leads to incorporating an extreme level of momentum (sometimes literally to the point of throwing weights) which inevitably leads to injury. We then turn around and blame our ailment on the weight–never even considering that the weight itself is not the issue but rather how we lifted that very weight that was the source of our issue. When a heavy load is lifted correctly (in the absence of momentum through a full range of motion), the forces the joints and soft tissues experience are extremely minimal and often times do not exceed the common forces we expose our joints to on a daily basis.

The second misunderstanding when it comes to heavy weights is that they cause muscles to get big and bulky (hypertrophy). This is yet again another confirmation bias at play. We assume heavy weights cause big muscles and then we see people with big muscles lifting heavy weights. Basic human anatomy shows us that muscle size is largely determined by numerous genetic factors such as length of muscle fibers, size of muscle fibers, number of fibers in a given muscle, hormonal profile, muscle protein turnover and satellite cell proliferation. From a training perspective, muscle hypertrophy appears to be stimulated most by taking a set to the point of muscle failure despite the load being lifted. A recent study out of McMaster University in Canada came to this conclusion when studying loads impact on muscle hypertrophy, “Muscular hypertrophy is similar between lower-load (30–50 %1RM) and higher-load (>70 %1RM) resistance exercise training when loads are lifted to the point of volitional fatigue; thus, load does not mediate resistance exercise training induced muscular hypertrophy.”

The reality is that heavy weights are not something that should be feared and avoided but rather utilized and applied correctly. In fact, they are an essential tenant to getting stronger. The fundamental problem with heavy weights is when they are lifted incorrectly (incorporating momentum into the movement) which drastically increases our risk for injury. When lifting weights, our focus should be on eliminating momentum and embracing the challenge of lifting the weight in a slow controlled manner through a full range of motion. This is how the best results are achieved.