There was a great study conducted at the University of Kentucky on the:
COMPARISON OF MUSCLE ACTIVATION AND KINEMATICS DURING THE DEADLIFT USING A DOUBLE‐PRONATED AND OVERHAND/UNDERHAND GRIP
Although the findings may seem mostly "common sense," I still felt as though this should be worthy of sharing, especially those of you who partake in the barbell deadlift on a regular basis.
So what can we summarize from these findings?
- Using an overhand/underhand grip can produce some bilateral asymmetries in muscle activation and joint angles. In other words, your arms will react differently based on what arm is facing palm forward and which one is facing palm backwards.
- Injury rates and/or asymmetries in strength or hypertrophic gains have yet to be fully determined from using an overhand/underhand grip, although it is still recommended to use a double overhand grip.
- Generally, lifters will use a double overhand grip for most "working" lifts, and just use a overhand/underhand grip for max lifts to aid in grip strength, however this study recommends using lifting aids such as wrist straps instead.
- If, however, an individual wishes to increase grip strength, then lifting straps should be avoided (less muscle activation in the forearms when wrist straps are used), and an overhand/underhand grip can be utilized. However, lifters should practice "flip-flopping" their grip in order to practice having a supinated grip with both hands/arms.
- It is common for individuals to prefer one hand/arm over the other when supinating/pronating their grips, but good training practice should take precedence here and train both sides equally to balance asymmetries.