Monday 3 September 2018

Full vs. Partial Range of Motion: Which is Best for Optimal Muscle Growth?

Building muscle is hard work. If you are going to tackle the challenge, you want to make it as efficient as possible. That means getting your training variables right. This includes not only sets and reps but also range of motion. Should you use full or partial range of motion? Is one more effective for building muscle? Let’s look at what the latest research has to say. 

In this month’s Journal of Strength & Condition Research, they published a review on full vs. partial range of motion training for muscle growth. I did the grunt work for you and went through the article. Below are the key takeaway points and some practical applications for you.

Newmire, D. E., & Willoughby, D. S. (2018). Partial Compared with Full Range of Motion Resistance Training for Muscle Hypertrophy: A Brief Review and an Identification of Potential Mechanisms. Journal of Strength and Conditioning Research, 32(9), 2652-2664. doi:10.1519/jsc.0000000000002723

Note: throughout the rest of this post, I will use ROM for “range of motion”

  • For muscle hypertrophy, ACSM (American College of Sports Medicine) recommends 7-12 reps with 70-85%1RM for 1-3 sets. They don’t give guidelines for ROM.
  • We generally say that full ROM is best, but at this point in the research, it is far from a being a closed case.
  • Some muscles are multi-joint. Take the triceps long head for example. It crosses the shoulder and elbow joint and thus does shoulder and elbow extension. As a result, you can’t train its full range of motion with only one exercise. 
  • Research shows that both full and partial ROM training can improve strength.
  • Some research shows partials can be helpful with hypertrophy and rehab. 
  • There is some concern in the research that partial ROM may decrease flexibility.
  • Optimal force production & muscle recruitment requires optimal myosin and actin cross-bridge formation. Is this something to consider in the discussion about optimal ROM?
  • Most ROM research uses single joint exercises (e.g. biceps curls). Currently, there is no established optimal ROM for multi-joint exercises. We need a lot more research to fully understand this.
  • With multijoint exercises, you have multiple muscles working at the same time. The optimal length for each muscle can be at different parts of the movement.
  • Pinto et al. (2012) compared machine biceps curls done with 0-130 degrees vs. 50-100 degrees. Full ROM increased muscle mass by 9.7%. Partial ROM training increased hypertrophy by 7.8%. For strength, full ROM increased strength by 25.7%. Partial ROM training increased strength by 16%.
  • McMahon et al. (2014) found greater muscle growth with squatting 0-90 degrees than squatting 0-50 degrees.
  • Bloomquist et al. (2013) also demonstrated greater hypertrophy with deep squats (0-120 degrees) compared to partial squats (0-60 degrees). It should be noted that there was some possible discrepancy with hypertrophy measurements.

The authors also looked at potential mechanisms to isolate and investigate. Here are some additional considerations: 

  • Partial ROM means less mechanical work. Remember work is calculated as force x distance. If you move the same weight for the same total reps but use a shorter ROM, you are doing less work.
  • Greater ROM may increase time under tension, which may lead to optimal hypertrophy stimulus.
  • Paoli et al. did EMG research on the DB Shoulder Press. They found that partial range reduces recruitment of other assistance muscles (e.g. upper traps, triceps).
  • Some research as also shown that hypertrophy gains can be non-uniform (i.e. different amounts of muscle growth at different spots of the same muscle). 

Practical Applications
Okay, so what does all this mean for you?

Based on the available research, this is far from being a closed case. However, based on what we do know, full range of motion seems to be better than partial range of motion.

When training for hypertrophy, keeping tension on the muscle is important. If you are using free weights, they need to be moving up against gravity to provide tension for your muscles. For example, I coach clients or students doing DB chest flies to stop before they get to the top since the last part of the motion has you moving the weights sideways. 

If you want to build muscle, check your ego at the door. Most guys naturally gravitate to easier ranges of motion so they can use more weight. However, more weight in an easier position just means more joint stress. A classic example of this is squat depth. As you could see from the research above, deeper squats yield better results. This is because the squat is just too mechanically efficient at the top. Effective hypertrophy training is about making exercises as hard on the muscles as safely possible. 

In your efforts to use a full range of motion, be sure that you are using YOUR full range of motion. For example, if you have long arms, you might exceed your natural shoulder joint range of motion trying to touch your chest with the bar when doing rowing or bench presses. Here is an example of this with DB bench press:

Since you are reading my blog, you probably want to get bigger and stronger. The law of specificity applies to range of motion. You won’t gain strength in a range that you don’t train.

As mentioned above, when you are doing exercises that involve multiple muscles, the dominant muscle may change depending on the range of motion. For example, in a bench press, the chest tends to be more dominant at the bottom while the triceps are more dominant at the top. If your goal is to target your triceps, you could do a floor press to limit the range of motion to the top part of the movement. 

Track your own results. As with many things training related, the current scientific body of knowledge leaves us with many unanswered questions. There is more research to be done. I’ll do my best to update you on new research, but be sure to do your own research on your body. Whatever ROM you decide to use, stay consistent with it and carefully measure your results. 

1 comment:

  1. Great write up Andrew. Maybe in a blog post in the future you could write about how partial ROM ca help strength development.