Assessing Utilized Body Weight with Planks

Type:  General Therapy & Training 

Assessing the Amount of Body Weight Utilized When Performing a Pushup or Plank Maneuver.
Carl Gustafson PT LATC CSCS , Shayna Glynn LATC PTA, Danielle Rooney DPT

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The last decade in fitness has brought about a return to more full body weight fitness activities. Medicine balls, kettle bells, boot camp calisthenics, yoga, and Pilates are now common place fitness activities. Circuit training machines have now taken a back seat to full bodyweight training.  With this return to more “Functional Training,” the trainer and client must take heed not advancing too quickly with full bodyweight as a resistance tool to prevent injuries.

 


This paper examined the percentage of bodyweight utilized in a common full bodyweight exercise: the “pushup” or “plank pose”. It also gives more conservative approaches to progress to this full body weight exercise. This may allow the client to reach the strength and coordination levels to perform a full pushup or plank movement with less chance of injury.


History:
The advent of Nautilus machines 30 years ago brought about a period where the fitness industry raced to compete with each other as to who would have the best machines. Machine designers tried to change the length of the lever arms and heights of seats to accommodate all body sizes. They attempted to make the resistance of the weight consistent throughout the range using cams. They made pulley systems more efficient to allow for more sports specific and functional movements. Some machines are motorized to allow for isokinetic training. The weight machine circuit allowed the very deconditioned or injured client to tolerate a full body workout, exercising one muscle group at a time. Exercise machine advocates argue that training injured muscle groups individually allows for quicker healing before full body movements are tolerated.


Some fitness specialists argue that this is a safer but more much expensive alternative for developing muscle. Functional trainers argue that fitting machines to all body sizes leaves the client more vulnerable to strain and that machines develop only the primary moving muscles that they were designed for, but the associated stabilizing muscles do not receive the same workout.


Although you might argue in favor of the functional trainers that returning to more full body weight exercises is more like real life situations, (i.e. picking up the garbage, lifting an overhead piece of luggage), we see a high number of injuries to patients who abruptly enter into full body weight resistance programs.  We usually find they are not conditioned enough to start using their full body weight during certain movements (i.e. pushups, chin ups, planks and side planks) or they may have enough strength, but use improper form. Boot camps, for example, that push quantity and not quality of movement or fitness facilities that stress one workout for all to do can lead to injury.
In our practice we see many patients who have hurt their shoulders from putting their body through the movement pattern pushup (as called in fitness class) or plank (as called in Pilates or yoga class).


The push up/plank position starts in this position (fig. 1.1) 
Push-up Positive
   fig. 1.1



This position to hold, and then lower, utilizes triceps, deltoids, pectoral, and serratus anterior as the primary movers. The client lowers their body down to where their chest touches the ground and the rises again when doing a pushup. (fig. 1.2)
Push-up Negative
  fig. 1.2

Or the patient may extend their spine and stay in this position if you are doing an Upward Facing Dog. (fig. 1.3)
Upward Facing Dog
   fig. 1.3


Data Gathering:
We gathered data from ten trainers and physical therapists in our company in four different positions: upright pushup position (positive position), low pushup position (negative position), upright pushup position with knees on ground, and low pushup position with knees on ground. (fig. 1.4)

Push up on scale to measure body weight utilized

   fig. 1.4

 

Our results indicated that in the upright or positive position, sixty-four of their bodyweight was supported on their arms and shoulders.  This percentage of weight was found by having a patient get into a pushup position with hands supported on a medical scale.

 

When they lower their body into the lower or negative position, they have to support seventy-one percent of their body weight. When the patient performs the same upper body motion but with knees on the ground, forty eight percent of their body weight is supported in their arms in the positive position and fifty-six percent in the negative position.  (See Table 1)

table: body weigh support during push-up

   Table 1



Utilizing this much of an athlete’s weight as a beginner can be straining to the shoulder and neck region, especially when there is no mention made to time held or repetitions. Our recommendation to our patients when performing a push up or a plank position is to keep track of time held in this position and number of repetitions so they can build strength in a progressive way.


If initially the patient is having difficulty holding this position second to strain, they can be instructed in utilizing a lesser percentage of their body weight by starting this movement pattern against a wall, then progressing to counter then back on to knees. (fig. 1.5)
Wall Push-up
   Fig. 1.5


If the patient has access to weight equipment, utilizing the movement pattern of the bench press is a great way to build strength in the same muscles utilized in the push up and plank position. (fig. 1.6)
Bench Press
   fig. 1.6

Discussion: 

The amount of force put through the patient’s arms, shoulders and cervical region is greater than 60-70 %of their body weight when performing a conventional push up or plank. The amount of weight used in the half pushup is close to 50% of the patient’s weight. Utilizing this much of your weight while taking no heed to form repetitions and sets could potentially injurious. A fitness instructor, trainer or therapist needs to keep a close eye on their clients for proper form and if the patient should start at an easier level of resistance such as the wall push up or bench press.


Conclusion:

As the fitness, personal training, and rehab community adopt full bodyweight exercises as part of their training programs special care should be taken to assess the true resistance someone is using. Just because we think utilizing their bodyweight is an appropriate level of resistance, the patient’s form and strength should first be taken into account.

 

 


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Maddalozzo, G.F., Snow, C.M. Effects of two resistance training protocols on insulin-like growth factors, muscle strength, and bone mass in older adults. Calcified Tissue International. 2000; 66(6), 399-404. 7.   


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McCaw, S.T., Friday, J.J.  A comparison of muscle activity between a free weight and machine bench press.

 

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Yoga Journal – Upward Facing Dog. http://www.yogajournal.com/poses/474. Updated 2011. Accessed September 30, 2011.

 

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