How Much Muscular Effort Is Used In Standing Yoga Postures?
Standing yoga postures vary in their physical demands
Research Study At A Glance
The Research Question Asked
What are the physical demands of seven common standing yoga postures?
Type of Study
Clinical research study
Study Participants (Sample)
Sample size: 14 women; 6 men
- 20 total participants
- Average age 70.7 +/- 3.8 years
- Participants were free of known health issues
- Participants demonstrated ability to move from a standing position to the floor and then return to standing
Methods
Senior-aged study participants completed a Hatha yoga class for 60 minutes twice per week for 32 weeks which included seven common standing yoga postures. Differences in the physical demand of postures was compared using calculated measures of physical effort called “net joint moments of force” and “support moment”. The physical demand was compared between postures, and between each posture and the amount of demand used by the same participant when walking.
Results
Four postures, which had the greatest support moment (a measurement of physical demand on the body), had greater support moments (placed greater demand on the body) than the peak support moment that occurred when the person was walking.
They included:
- Crescent with the dominant leg forward
- Chair
- Warrior two with the dominant leg forward
- One-legged balance
Side stretch with the dominant leg forward and crescent with the dominant leg forward had the greatest joint moment of force (JMOF; another measurement of the physical demand of a position on the body) in the sagittal plane.
Tree pose and warrior two had the greatest JMOF in the frontal plane.
Conclusion
Biomechanical demand at the hip, knee, and ankle joints, varied significantly between standing yoga postures, suggesting some postures may be more appropriate for some populations than others, or they may need to be modified to a variation more appropriate for an older population who are novices to yoga.
Background
Older folks are finding yoga in ever greater numbers, primarily with an interest in using yoga as a gentler way to continue incorporating movement into their life when more demanding activities like running are no longer accessible. Research supports yoga as one practice that can contribute to increased flexibility, strength, proprioception, and balance — all qualities frequently sought after by older adults. As yoga is still a physical practice however, there is concern about how to structure yoga for older populations. It is important to take into consideration their increased risk of strains, sprains, impingements, etc. in the event that they fall or simply over-do compared to what their body is able to do. For those reasons this research team decided to evaluate seven common standing yoga postures to determine in a laboratory setting what the biomechanical demands actually are.
Research question
What are the physical demands of seven common standing yoga postures?
Research methods
Senior-aged study participants (average age 70.7 +/- 3.8 years) completed a Hatha yoga class for 60 minutes twice per week. Seven common standing yoga postures were evaluated in the study including: chair, wall-plank, tree, warrior two, side stretch, crescent, and one-legged balance. The yoga classes in the study lasted for 32 weeks and participants attended 80-85% of the classes. Props such as foam blocks were used for some postures such as one-legged balance posture, crescent, and side stretch. For the single limb postures, the dominant limb side was used in the study for evaluation.
To evaluate the physical demands of seven common standing yoga postures, the research team calculated “net joint moments of force” and “support moment”. In order to calculate these important measures of physical demand, researchers measured individual “joint moments of force” at three main joints of the lower body: hip, knee, and ankle. “Moment” is a measurement of the force that acts on an object which is at a distance from its center of mass. So, this is a very technical way of saying that the research team calculated the physical demand needed to maintain each of these standing yoga postures by measuring the physical demand on the body at each of three individual joints and then combining those measurements in different ways to get two different ways to compare that physical demand. Those are called: net joint moments of force and support moment. The physical demand of each of the postures was compared between postures, and between each posture and the amount of demand used by the same participant when walking.
Results
All postures generated less electromyographic (EMG) activity specifically from the gastrocnemius, hamstrings, vastus lateralis, and gluteus medius, than walking, with most posture-muscle combinations using considerably less activity than walking.
The following standing yoga postures had the greatest support moments (one measurement of the physical demand of a position on the body):
- Crescent with the dominant leg forward
- Chair
- Warrior two with the dominant leg forward
- One-legged balance
- All of these postures had greater support moments (placed greater demand on the body) than the peak support moment that occurred when the person was walking.
The following postures had the greatest joint moment of force (JMOF; another measurement of the physical demand of a position on the body) in the sagittal plane movements:
- Side stretch with the dominant leg forward
- Crescent with the dominant leg forward
The following postures had the greatest JMOF in the frontal plane movements:
- Tree pose
- Warrior two
- Only warrior two generated greater JMOF than walking.
Why is this relevant to yoga practitioners?
Yoga is an appealing option for many older folks who would like to include more movement in their life, but would prefer activities that offer less risk for strains, sprains, or simply over-taxing compared to what their body is able to do. But, not all yoga postures are the same. When structuring yoga practices for an older population, it’s important to have an understanding of which postures are more demanding of the body, and then how to modify those postures when appropriate. Yoga offers an older population many potential benefits, including the potential for increased flexibility, strength, balance, and proprioception. Evaluating the physical demand of certain common yoga postures can help inform yoga sequencing for a senior population, increasing the likelihood that participants experience those benefits, while reducing the risk of injury or negative effects.
