Research and News
Posts tagged EMG
Exercise on unstable surfaces increases trunk muscle activation
Nov 4th
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Unstable surfaces have become more popular for balance and stabilization training. Thera-Band® Exercise Balls and Stability Discs offer multiple options for unstable surface training. These unstable surfaces are thought to increase muscle activation and co-contraction, particularly for core stabilization training. Japanese researchers investigated the effect of unstable surface training on trunk muscle activity during common lumbar stabilization exercises in 19 healthy subjects. Their findings were published in the Journal of Orthopedic and Sports Physical Therapy.
The researchers used surface electromyography (EMG) to assess the “global” muscles: rectus abdominus, erector spinae, and external obliques, and fine-wire EMG for the deeper “local” muscles: transverse abdominus and multifidus. The subjects performed 5 lumbar stabilization exercises for 3-second holds, both on stable and unstable surfaces. The exercises were: prone plank on elbows, supine bridge, quadruped arm-and-leg, side bridge, and curl-up. EMG levels were normalized to maximal contraction.
The prone plank exercise on unstable surfaces (including an exercise ball and stability disk) produced significantly more muscle activity of all core muscles. High levels of oblique and rectus muscles were noted in both conditions for the prone plank exercise. The supine More >
Evidence-based exercise prescription for Thera-Band® shoulder exercises
Oct 21st
Shoulder rehabilitation exercises are commonly performed with Thera-Band® resistance bands and dumbbells. Electromyography (EMG) is commonly used to quantify the muscle activity of these exercises to help clinicians determine which exercises are most effective at activating muscle. Several studies have been published that evaluate the EMG levels of common shoulder exercises. Unfortunately, it’s difficult to compare the results of these studies since they often 1) assess different muscles; 2) use different intensities and types of resistance; 3) quantify the level of contraction differently; and 4) use different analysis techniques. In addition, these studies are typically performed on healthy individuals without shoulder pathology, limiting our understanding of the effects of these exercises on shoulder patients. These issues all limit our evidence-based clinical decision making.
Dr. Rafael Escamilla of the Andrews Institute for Orthopedics and Sports Medicine in Florida published an excellent review of shoulder function and muscle activation studies in Sports Medicine. Dr. Escamilla and his colleagues described relevant biomechanics and function of the rotator cuff, deltoid, and scapular muscles. His colleagues then reviewed 8 EMG studies evaluating various shoulder exercises, modes of resistance, and muscles. Exercises with ‘high’ to ‘very high’ activation (> 41% maximum contraction) were identified.
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EMG evidence helps support evidence-based practice with Thera-Band
Oct 7th
Electromyography (EMG) is a helpful tool for clinicians to decide which exercise would be best for their patients rehabilitation. Many studies have investigated the muscle activation levels of elastic resistance, including Thera-Band® resistance bands. Dr. Todd Ellenbecker of Physiotherapy Associates in Scottsdale, Arizona, investigated the EMG levels of 2 Thera-Band exercises he uses in his clinic. “We use these exercises on our patients, yet we don’t exactly know the muscle activation levels,” Dr. Ellenbecker noted, “EMG testing will help us make better clinical decisions for exercise prescription.”
Dr. Ellenbecker presented his findings at the 2010 Thera-Band Research Advisory Committee (TRAC) meeting. 21 subjects performed an external rotation oscillation with the FlexBar® exerciser and a Thera-Band Band Loop Wall Walk. The researchers measured surface EMG levels of the deltoid, rotator cuff and scapular stabilizers. Interestingly, both exercises produced similar levels of activation. The most active muscle for both exercises was the infraspinatus of the rotator cuff, which had moderate activation levels. Interestingly, the ratios of the upper trapezius to lower trapezius were over 1:1 for both exercises. “That’s important because we like to bias the lower trapezius, which is usually weaker than the upper trapezius in shoulder patients,” said Dr. Ellenbecker. His research helps More >
Abduction exercise after hip replacement: is there an optimal progression?
Aug 23rd
Patients undergoing total hip replacement often have weak hip abductor muscles before and after surgery. One of the most common hip exercises is sidelying hip abduction using an ankle weight. While this may be an effective exercise to activate the gluteus medius muscle, open-chain, non-weight bearing hip abduction is not specific to the function of the gluteus medius as a pelvic stabilizer in single-leg stance. Resisted lateral walking with a Thera-Band® Band Loop or Tubing with Cuffs is an example of such a closed-chain exercise as the patient steps away from the involved leg.
Researchers at the University of Kentucky evaluated electromyographic (EMG) levels of 4 exercises in total hip patients between 7 and 32 weeks post-operative. Dr. Cale Jacobs and colleagues were interested to see if there was a progression of muscle activation to guide clinical decisions about hip abduction exercise prescription. They published their findings in the Journal of Arthroplasty. The 4 exercises included 2 non-weight bearing and 2 weight-bearing exercises:
- Standing hip abduction with cuff weight at 1% of bodyweight, lifted to 30 degrees
- Sidelying hip abduction with cuff weight at 0.5% of bodyweight, lifted to 50% of leg length
- Standing hip abduction with uninvolved leg to 30 degrees
- Lateral walk with Thera-Band resistance band attached with More >
