Effects of the JAQBLOQ Forearm and Straight Arm Plank on Core Muscle Activation

Performing a plank has various benefits for all fitness levels. There are several different types of planks that can be performed, with or without equipment: straight arm, forearm and side plank. When one has a shoulder or arm injury, he or she will not be able to safely perform a plank. A piece of fitness equipment was recently designed to aid people with injuries so they can still perform a plank; the JAQBLOQ. It is a 12x13x14" high density EVA foam block used to assist one during a plank where the participant rests his or her chest on it. This study examined the difference between EMG muscle activation in the anterior deltoid, rectus abdominus and external oblique during the JAQBLOQ plank, forearm plank, and straight arm plank. There were 20 participants recruited for this study; 10 men and 10 women. One subject was excluded for his or her inability to complete the required tasks. Participants that were physically active with no shoulder injuries in the past six months, no cosmetic surgery in the past year, no orthopedic shoulder, back or neck surgery, and not currently pregnant, were recruited for the study. Participants were recruited based on a BMI less than or equal to 25 kg m-2. They were instructed to hold each plank for 30 seconds with a five-minute rest in between. Results showed that during testing, participants' anterior deltoid produced activations of 4.1 ± 7.2% maximal voluntary isometric contraction (MVIC) for JAQBLOQ, 39.1 ± 23.8% MVIC for straight arm, and 42.0±20.9% MVIC for forearm. There was higher average muscle activation in the rectus abdominis during the forearm 30.2 ± 26.0 as opposed to straight arm 20.1 ± 16.7 and JAQBLOQ 5.3 ± 4.3. There was higher average muscle activation in the external obliques during forearm 29.7 ± 14.0 as opposed to straight arm 22.2 ± 12.5 and JAQBLOQ 17.7 ± 15.9. There was a significant difference (p<0.001) in EMO activity during the planks. The JAQBLOQ plank had significantly less EMO activity than the straight arm plank. The JAQBLOQ plank had significantly less EMO activity than the forearm plank. The straight arm plank had significantly less EMO activity than the forearm plank. The greater activation of the deltoid during the straight arm and forearm planks compared to the JAQBLOQ plank demonstrates that the JAQBLOQ was successful in greatly reducing the effort required by the shoulders. Regarding abdominal muscles, the JAQBLOQ plank reduced activation of the recuts abdominis while still eliciting good activation of the external obliques. In addition, there was higher muscle activation in the abdominals and deltoid during the forearm plank in comparison to the JAQBLOQ plank and straight arm plank.