Which Muscles Are You Using in Your Yoga Practice? A New Study Provides the Answers

By: 
B Grace Bullock, PhD, E-RYT 500

 Have you noticed that your yoga practice leads to an increase in bodily awareness and greater efficiency of movement?  A groundbreaking new study shows which muscles you use during certain poses, and suggests that our ability to effectively recruit key muscle groups increases with time and practice.

The study, which was published in Complementary Therapies in Medicine, is the first published account of the key muscles activated during the 11 distinct postures in the Surya Namaskar (sun salutation) A and B sequences. It not only shows you which muscles are activated, but also examines how novice and advanced students and yoga instructors use their bodies differently in the same pose.

Researchers at the University of Miami recruited 36, healthy volunteers who had practiced Baptiste yoga using “Vinyasa style” for 3 months or more or had yoga instructor certification. Participants included 9 male and 27 female adults ranging in age from 19-43 years. Each was required to have the ability to complete Surya Namaskar A and B independently, and to be free of musculoskeletal or neurologic injury or impairment.

Yoga participants were divided into 1 of 3 categories: novice (12, mean age 24 years), advanced (12, mean age 36 years), and instructor (12, 34 years). They were asked to come to a laboratory and to warm up by performing Surya Namaskar A 3 times and B twice. Electrodes were then placed on the skin over the identified muscles on the participant’s dominant side (27 right handed/3 left handed).

Each participant was then asked to perform a sequence of the 11 Surya Namaskar poses, and to hold each for a period of 15 seconds. The poses included:

Urdhva Mukha Uttanasana (“halfway lift”)
Uttanasana (forward fold)
Adho Mukha Svanasana (downward facing dog)
Urdvha Mukha Svanasana (upward facing dog)
Dandasana (high plank)
Chaturanga dandasana (low plank)
Utkatasana (chair)
Urdvha Hastasana (mountain with arms up)
Tadasana (mountain arms down)
Virabhadrasana (dominant side warrior 1 pose) and nondominant side Virabhadrasana

Each pose was digitally recorded, then evaluated by an independent sample of yoga instructors blind to the participant’s yoga history, who were asked to independently evaluate each participant’s skill level.

A total of 14 muscle groups were examined. They included:

Pectoralis major (PECS)
Deltoid anterior (DELTa)
Deltoid medial (DELTm)
Biceps brachii (BB)
Triceps brachii (TB)
Upper trapezius (TRAPu)
Middle trapezius (TRAPm)
Rectus abdominus (RA)
Erector spinae (ES)
Rectus femoris (RF)
Vastus medialis (VM)
Biceps femoris (BF)
Gastrocnemius lateralis (GL)
Tibialis anterior

The investigators then statistically analyzed each of the muscle activation patterns by group (novice, advanced and instructor), and by pose.

Fascinating results

The experimenters discovered a number of interesting patterns of results.

For the upper body, the upper trapezius muscle showed high activation patterns for chair, downward facing dog, and warrior. The biceps brachii were most active during chair pose, and engaged in high and low plank, and upward facing dog as one might expect. Triceps brachii were most employed during Chaturanga, and somewhat for chair, warrior, plank and upward facing dog.

The erector spinae muscles showed greater activation during chair, “halfway lift” (Urdhva Mukha Uttanasana), upward dog, and warrior as compared to downward facing dog, forward fold, and mountain pose.

Muscles of the lower body also responded in an expected fashion. Values for the rectus femoris were greatest during chair pose, downward dog, high plank, and warrior compared to forward fold, and elevated during up dog and warrior pose when compared to “halfway lift.”

The biceps femoris on the other hand, showed higher patterns of activation during chair, high and low plank, upward dog and warrior pose compared to forward fold.

Lastly, the tibialis anterior was most engaged during chair, downward dog, high and low plank and warrior compared to the more passive mountain and forward fold poses.

Skill is a factor

There was some evidence that the skill level of the yoga practitioner has implications for muscle recruitment and intensity of activation. In general, instructors were found to have higher levels of muscle activation compared to novices. This is to be expected as body awareness, proprioception and postural refinement evolve with practice.

A number of interesting patterns of muscle activation also emerged. There were significant differences in pectoral muscle use by skill group. Novices generally had the most pec engagement in chair when compared to instructors. Instructors showed markedly higher activation of the anterior deltoid muscles during forward folds and warrior pose. In general, instructors made greater use of their deltoid muscles than either novices or advanced practitioners.

There were no significant differences in core muscle activation between instructors, novices and advanced students. For lower body muscles, however, instructors showed greater patterns of activation for their gastrocnemius muscles for “halfway lift” and warrior than the other two groups.

Skill level, muscle use – What are the implications?

The authors drew a number of important conclusions regarding their findings. Most importantly, these data suggest that more advanced yoga practitioners are able to engage their trapezius and erector spinae muscles more readily during postures that require upper body strength rather than relying more heavily on shoulder muscles. It is likely that, with experience, yoga practitioners become increasingly more adept at retracting their scapula and engaging spinal stabilizers and middle trapezius muscles rather than relying on the shoulder joints for support. This is likely to reduce injury over time.

In addition to back strength and stability, the authors discovered that postures such as chair and warrior target the tibialis anterior, a critical dorsiflexor associated with foot and ankle stability and decreased fall risk, particularly among the elderly. This points to the tibialis anterior as a key target of intervention for programs intending to promote postural stability.

Lastly, the authors draw attention to the importance of the vastus medialis (VM). The VM is a critical knee stabilizer and of great importance in maintaining balanced force distribution between the upper and lower body during high and low plank, and upward and downward facing dog pose. Highest activation of this muscle was found in the instructors, who have likely developed their ability to detect and engage this muscle during strenuous postures.

It is essential that yoga teachers and students continue to familiarize themselves with core and spinal stabilizers in order to maintain a safe and integrated practice.

The great news

…. is that the patterns of muscle activation detected in this study are consistent with a lot of what we already know about these postures. These findings also speak to the benefits of practice for cultivating greater body awareness, and a heightened sensitivity to the patterns of muscle engagement that will result in greatest benefit and physical efficiency. 

 

B Grace Bullock, PhD, E-RYT 500, is the Founding Director of the International Science & Education Alliance, a firm that provides strategic planning, research consultation and assessment design to support the empirically rigorous evaluation and sustainable implementation of programs in education, leadership, health and human services. Grace is an intervention scientist, psychologist, yoga educator and author who has worked extensively in integrated behavioral health settings. Her research, clinical practice, teaching and writing emphasize the incorporation of empirically supported psychotherapy with yoga therapy and mindfulness practices to relieve the symptoms of stress, trauma, anxiety, depression and other psychological illnesses, and to promote healthy relationships. She is Faculty at the Integrated Health Yoga Therapy therapist training program, and Professor of Yoga & Neuroscience at the Taksha University School of Integrative Medicine. Grace is the former Editor in Chief of the International Journal of Yoga Therapy and recipient of a Francisco J. Varela Research Award from the Mind & Life Institute. For more information contact Grace at bgracebullock@me.com or see http://isaeaorg.wix.com/isaea,.

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