Surface Electromyography of the Vastus Lateralis, Biceps Femoris, and Gluteus Medius Muscle in Sound Dogs During Walking and Specific Physiotherapeutic Exercises Katharina Breitfuss1, DVM, Michaela Franz1, DVM, Christian Peham2, DME, PhD, and Barbara Bockstahler1, DVM 1
Clinic for Small Animal Surgery, Department for Companion Animals and Horses, University of Veterinary Medicine, Vienna, Austria and Movement Science Group Vienna, Department for Companion Animals and Horses, University of Veterinary Medicine, Vienna, Austria
Corresponding Author Barbara Bockstahler, DVM, Clinic for Small Animal Surgery, Department for Companion Animals and Horses, University of Veterinary Medicine, Veterinaerplatz 1, 1210 Vienna, Austria. E‐mail: [email protected] Submitted October 2013 Accepted September 2014 DOI:10.1111/j.1532-950X.2014.12302.x
Objective: To analyze the muscle activity patterns of the vastus lateralis (VL), biceps femoris (BF), and gluteus medius (GM) during walking and specific physiotherapeutic exercises in clinically sound, healthy dogs without lameness. Study Design: Observational study. Animals: Clinically sound dogs (n ¼ 10). Methods: Surface electromyography was performed during walking and exercises (11% incline and decline, walking over cavaletti) within a defined study area. The maximal, minimal, and mean muscle potentials reflecting activity during each motion cycle were compared among the exercises. Results: During swing phase, maximal VL activity was higher during cavaletti walking compared with walking over ground or incline. Cavaletti walking had an earlier occurrence of the maximum VL activity than did walking over ground or decline. Compared with walking over ground, incline walking had higher minimal GM activity during the 1st half of stance phase and an earlier occurrence of maximal activity during the 2nd half of stance phase. Cavaletti walking had earlier maximal GM activity in swing phase than did walking over ground. Differences between decline and incline walking were seen in all 3 phases of the motion cycle; namely, higher minimal and mean activities occurred during incline walking, and higher maximum activity occurred in the 1st half of stance phase during incline walking. Compared with decline walking, cavaletti walking showed higher minimal and mean activities in the 2nd half of stance phase and higher maximal and mean activities in swing phase. Conclusion: Cavaletti and incline walking exercises increases the VL and GM muscle activity.
Physiotherapeutic exercises are an important part of therapy in dogs with impaired motion and decreased neuromuscular function associated with orthopedic and neurologic problems.1,2 Different exercises are thought to activate and train different muscles. Thus, precise knowledge of joint biomechanics and muscle activity is necessary to develop an individual training plan for each patient. The specific needs and functional limitations of each dog must be taken into account during rehabilitation. Several studies have evaluated canine kinematics and muscle activity using needle electromyography3,4 or surface electromyography (sEMG) during walking.5–7 One study reported an increase in muscle activity of the biceps femoris (BF), vastus lateralis (VL), and gluteus medius (GM) during stance phase compared to swing phase,3 Presented in part at the 7th International Symposium of Veterinary Rehabilitation and Physical Therapy in Vienna, Austria, August 2012.
588
2
and another reported minimal changes in the muscle activity of the thoracic limb comparing incline and decline walking, carrying additional weight, and leash pulling.4 Many studies have used kinematic measurements to describe and compare the range of motion (ROM) in specific parts of the body, especially in the joints.5,8–14 In 1 study, thoracic and pelvic limb joint range of extension and flexion differed significantly in clinically sound dogs when comparing walking over ground, on an incline, on a decline, and over obstacles.14 Stifle joint flexion decreased and hip joint flexion increased significantly when walking on an incline compared to walking over ground while hip joint flexion decreased when walking on a decline compared to walking over ground.14 Another study compared the range of motion of the pelvic limb joints between sound dogs and dogs with surgically corrected (debridement of the ruptured CCL, partial or complete medial meniscectomy, and extracapsular stabilization) cranial cruciate ligament rupture during walking on a treadmill and
Veterinary Surgery 44 (2015) 588–595 © Copyright 2014 by The American College of Veterinary Surgeons
Breitfuss et al.
Surface Electromyography in Sound Dogs During Walking and Specific Exercises
swimming.15 In this study, hip ROM was higher in healthy dogs only, whereas stifle and tarsal ROM was higher in healthy as well as in the dogs with surgically corrected cranial cruciate ligament when comparing swimming to walking. Although such kinematic measurements provide very detailed information on joint biomechanics, the effect of movements like walking uphill or downhill, walking over obstacles, or swimming cannot be fully understood without precise knowledge of muscle function. Bockstahler et al.5 simultaneously evaluated the kinetics, kinematics, and sEMG of the VL and described the activity pattern of this muscle at the walk in relation to the kinetics and kinematics of the pelvic limb. The VL muscle activity measurement revealed a 2 peak activity pattern similar to the kinetics of this muscle. Bockstahler et al.6 compared the activity patterns of the VL, BF, and GM muscles in 7 clinically sound dogs with those of 10 dogs with hip osteoarthritis during the normal walk. The muscles showed a distinct resting phase during the swing phase and higher activity during the early stance phase in the lame limb. Lauer et al.7 investigated 8 clinically sound dogs by sEMG and kinematic analysis to evaluate the effects of incline and decline treadmill walking versus planar surface walking on the pelvic limb muscle activity and range of motion. Neither incline nor decline walking affected swing or stance phase duration, or step length. Significantly higher hamstring activity was detected during incline walking than during decline walking, whereas the GM and quadriceps femoris activities remained unchanged. Our purpose was to compare the activity patterns of the BF, GM, and VL muscles in clinically sound dogs during the different exercise regimens described by Holler et al.14 We hypothesized that muscle activity during walking on an incline, decline, and over cavaletti differs from walking over ground. We postulated that higher muscle activity would be exhibited during walking on an incline than during walking on a decline, whereas walking over obstacles would result in a muscle activity pattern different from that during walking over ground. Our results should guide clinicians in selection of specific exercises that may strengthen BF, GM, and VL in dogs during physical rehabilitation.
MATERIALS AND METHODS This study was approved by our institutional ethics committee (ref. 09/04/97/2007). Dogs Privately owned and clinically sound dogs (n ¼ 10; 4 Labrador Retrievers, 3 Border Collies, 1 Golden Retriever, 1 Australian shepherd, and 1 German Shorthaired Pointer) were studied. Dog ages and weights ranged from 1 to 7 years (mean SD, 3.90 2.02 years) and 21–28 kg (mean, 24.70 4.40 kg), respectively. Dogs were only included in the study if they had a normal body mass with a body condition score of 3 on a scale of 5.16 Seven dogs were female (3 spayed) and 3 were male. Mean shoulder height was 54.5 4.27 cm.
All dogs had a complete orthopedic and neurologic examination. Dogs were not included if they showed any signs of visible lameness or pain upon palpation of the joints, spine, or skeletal muscles or if a gait abnormality at the walk or trot, posture abnormality, or any other neurologic deficit was detected. Kinetic Measurements Kinetic measurements were performed to exclude any lameness or abnormal 4 limb weight‐bearing distribution that had not been clinically detected. On a treadmill with 4 integrated force plates and speed of 0.6 0.07 m/s, ground reaction force was measured (Type 9011 A; Kistler Instruments, Ostfildern, Germany).14 Measurements were started as soon as each dog had established a constant smooth, well‐coordinated gait. Kinematic Measurements A self‐reflecting marker was glued onto the skin surface of the distal aspect of the right lateral metatarsus to perform motion cycle (MC) sequencing. Ten digital infrared cameras (Eagle Digital Real‐Time System; Motion Analysis Corporation, Santa Rosa, CA) recorded the motion of the marker. Data were captured and analyzed using a personal computer and motion‐ analysis program (EVaRT, version 5.0.4; Motion Analysis Corporation). sEMG Muscle potentials were recorded by a telemetric unit (Telemyo 8/16; Noraxon USA, Inc., Scottsdale, AZ). Self‐adhesive surface electrodes (Blue Sensor; Ambu, Ballerup, Denmark) were positioned and glued onto the shaved skin of the right pelvic limb. The muscles examined were the VL, the cranial part of the BF, and the GM. For each muscle, 2 electrodes were placed 1 cm apart with the dog in a standing position and the feet positioned squarely underneath the body. The same examiner placed the electrodes onto each muscle to ensure exact positioning. For the BF muscle, the electrodes were placed in the middle third of the distance between the ischial tuberosity and patella. For the VL muscle, the distance between the iliac crest and patella and between the patella and greater trochanter were measured.13 The central points of these lines were connected, and the electrodes were placed in the center of the resulting line. For the GM muscle, the electrodes were placed at the midpoint of the distance between the iliac crest and greater trochanter. All sEMG measurements were performed at 1200 Hz. Measurement Procedure All measurements were performed on a horse treadmill (Mustang 2200; Graber AG, Fahrwangen, Switzerland) to ensure a constant and reproducible testing area. The treadmill was locked and stationary during all measurements. The slope
Veterinary Surgery 44 (2015) 588–595 © Copyright 2014 by The American College of Veterinary Surgeons
589
Surface Electromyography in Sound Dogs During Walking and Specific Exercises
was inclined and declined to allow for walking uphill and downhill, respectively. Ten cameras were placed around the measurement area, and kinematic and sEMG measurements were performed as described by Bockstahler et al.6 and Holler et al.14 Five height‐adjustable cavaletti (timber jumps) were positioned as obstacles within the testing area. Five assessments of each dog were performed during consecutive walking over ground, uphill and downhill walking, and walking over obstacles. All exercises were performed in the same order with a 10‐min break to allow for rebuilding of the testing area after each exercise. Before the testing sessions were recorded, the dogs’ owners helped to acclimatize the dogs to the environment by guiding them through the testing area 3–5 times, depending on the dog. The treadmill was adjusted to 11% (angle, 9.9°) to produce an uphill or downhill slope. For the cavaletti exercise, the obstacles were adjusted to the height of the dogs’ carpal joints from the ground. The distance between each obstacle was set accordingly to the distance between the thoracic limb and pelvic limb of each dog.14 Dogs were allowed to comfortably walk at their own speed. Each dog’s velocity during each activity varied: 1.06 0.21 m/s for normal walking, 1.07 0.17 m/s for uphill walking, 1.10 0.16 m/s for downhill walking, and 0.89 0.11 m/s for walking over obstacles. Data Processing Kinetic measurements were performed as follows. Ground reaction forces were measured at 300 Hz and analyzed with motion analysis software (SIMI Motion, version 6.5; SIMI Reality Motion Systems, Unterschleissheim, Germany). Peak vertical force (PFz), vertical impulse (IFz), and mean vertical force (MFz) were measured in each dog. The results were compared between the left and right pelvic limbs to calculate the symmetry index using the following formula (modified from Budsberg et al.17): SIx ¼ (Xl Xr)/(Xl þ Xr), where SIx ¼ the symmetry index of the parameter; Xl ¼ PFz, IFz, and MFz of the left pelvic leg; and Xr ¼ PFz, IFz, and MFz of the right pelvic leg. A value of zero represents absolute symmetry, and values of
Clinic for Small Animal Surgery, Department for Companion Animals and Horses, University of Veterinary Medicine, Vienna, Austria and Movement Science Group Vienna, Department for Companion Animals and Horses, University of Veterinary Medicine, Vienna, Austria
Corresponding Author Barbara Bockstahler, DVM, Clinic for Small Animal Surgery, Department for Companion Animals and Horses, University of Veterinary Medicine, Veterinaerplatz 1, 1210 Vienna, Austria. E‐mail: [email protected] Submitted October 2013 Accepted September 2014 DOI:10.1111/j.1532-950X.2014.12302.x
Objective: To analyze the muscle activity patterns of the vastus lateralis (VL), biceps femoris (BF), and gluteus medius (GM) during walking and specific physiotherapeutic exercises in clinically sound, healthy dogs without lameness. Study Design: Observational study. Animals: Clinically sound dogs (n ¼ 10). Methods: Surface electromyography was performed during walking and exercises (11% incline and decline, walking over cavaletti) within a defined study area. The maximal, minimal, and mean muscle potentials reflecting activity during each motion cycle were compared among the exercises. Results: During swing phase, maximal VL activity was higher during cavaletti walking compared with walking over ground or incline. Cavaletti walking had an earlier occurrence of the maximum VL activity than did walking over ground or decline. Compared with walking over ground, incline walking had higher minimal GM activity during the 1st half of stance phase and an earlier occurrence of maximal activity during the 2nd half of stance phase. Cavaletti walking had earlier maximal GM activity in swing phase than did walking over ground. Differences between decline and incline walking were seen in all 3 phases of the motion cycle; namely, higher minimal and mean activities occurred during incline walking, and higher maximum activity occurred in the 1st half of stance phase during incline walking. Compared with decline walking, cavaletti walking showed higher minimal and mean activities in the 2nd half of stance phase and higher maximal and mean activities in swing phase. Conclusion: Cavaletti and incline walking exercises increases the VL and GM muscle activity.
Physiotherapeutic exercises are an important part of therapy in dogs with impaired motion and decreased neuromuscular function associated with orthopedic and neurologic problems.1,2 Different exercises are thought to activate and train different muscles. Thus, precise knowledge of joint biomechanics and muscle activity is necessary to develop an individual training plan for each patient. The specific needs and functional limitations of each dog must be taken into account during rehabilitation. Several studies have evaluated canine kinematics and muscle activity using needle electromyography3,4 or surface electromyography (sEMG) during walking.5–7 One study reported an increase in muscle activity of the biceps femoris (BF), vastus lateralis (VL), and gluteus medius (GM) during stance phase compared to swing phase,3 Presented in part at the 7th International Symposium of Veterinary Rehabilitation and Physical Therapy in Vienna, Austria, August 2012.
588
2
and another reported minimal changes in the muscle activity of the thoracic limb comparing incline and decline walking, carrying additional weight, and leash pulling.4 Many studies have used kinematic measurements to describe and compare the range of motion (ROM) in specific parts of the body, especially in the joints.5,8–14 In 1 study, thoracic and pelvic limb joint range of extension and flexion differed significantly in clinically sound dogs when comparing walking over ground, on an incline, on a decline, and over obstacles.14 Stifle joint flexion decreased and hip joint flexion increased significantly when walking on an incline compared to walking over ground while hip joint flexion decreased when walking on a decline compared to walking over ground.14 Another study compared the range of motion of the pelvic limb joints between sound dogs and dogs with surgically corrected (debridement of the ruptured CCL, partial or complete medial meniscectomy, and extracapsular stabilization) cranial cruciate ligament rupture during walking on a treadmill and
Veterinary Surgery 44 (2015) 588–595 © Copyright 2014 by The American College of Veterinary Surgeons
Breitfuss et al.
Surface Electromyography in Sound Dogs During Walking and Specific Exercises
swimming.15 In this study, hip ROM was higher in healthy dogs only, whereas stifle and tarsal ROM was higher in healthy as well as in the dogs with surgically corrected cranial cruciate ligament when comparing swimming to walking. Although such kinematic measurements provide very detailed information on joint biomechanics, the effect of movements like walking uphill or downhill, walking over obstacles, or swimming cannot be fully understood without precise knowledge of muscle function. Bockstahler et al.5 simultaneously evaluated the kinetics, kinematics, and sEMG of the VL and described the activity pattern of this muscle at the walk in relation to the kinetics and kinematics of the pelvic limb. The VL muscle activity measurement revealed a 2 peak activity pattern similar to the kinetics of this muscle. Bockstahler et al.6 compared the activity patterns of the VL, BF, and GM muscles in 7 clinically sound dogs with those of 10 dogs with hip osteoarthritis during the normal walk. The muscles showed a distinct resting phase during the swing phase and higher activity during the early stance phase in the lame limb. Lauer et al.7 investigated 8 clinically sound dogs by sEMG and kinematic analysis to evaluate the effects of incline and decline treadmill walking versus planar surface walking on the pelvic limb muscle activity and range of motion. Neither incline nor decline walking affected swing or stance phase duration, or step length. Significantly higher hamstring activity was detected during incline walking than during decline walking, whereas the GM and quadriceps femoris activities remained unchanged. Our purpose was to compare the activity patterns of the BF, GM, and VL muscles in clinically sound dogs during the different exercise regimens described by Holler et al.14 We hypothesized that muscle activity during walking on an incline, decline, and over cavaletti differs from walking over ground. We postulated that higher muscle activity would be exhibited during walking on an incline than during walking on a decline, whereas walking over obstacles would result in a muscle activity pattern different from that during walking over ground. Our results should guide clinicians in selection of specific exercises that may strengthen BF, GM, and VL in dogs during physical rehabilitation.
MATERIALS AND METHODS This study was approved by our institutional ethics committee (ref. 09/04/97/2007). Dogs Privately owned and clinically sound dogs (n ¼ 10; 4 Labrador Retrievers, 3 Border Collies, 1 Golden Retriever, 1 Australian shepherd, and 1 German Shorthaired Pointer) were studied. Dog ages and weights ranged from 1 to 7 years (mean SD, 3.90 2.02 years) and 21–28 kg (mean, 24.70 4.40 kg), respectively. Dogs were only included in the study if they had a normal body mass with a body condition score of 3 on a scale of 5.16 Seven dogs were female (3 spayed) and 3 were male. Mean shoulder height was 54.5 4.27 cm.
All dogs had a complete orthopedic and neurologic examination. Dogs were not included if they showed any signs of visible lameness or pain upon palpation of the joints, spine, or skeletal muscles or if a gait abnormality at the walk or trot, posture abnormality, or any other neurologic deficit was detected. Kinetic Measurements Kinetic measurements were performed to exclude any lameness or abnormal 4 limb weight‐bearing distribution that had not been clinically detected. On a treadmill with 4 integrated force plates and speed of 0.6 0.07 m/s, ground reaction force was measured (Type 9011 A; Kistler Instruments, Ostfildern, Germany).14 Measurements were started as soon as each dog had established a constant smooth, well‐coordinated gait. Kinematic Measurements A self‐reflecting marker was glued onto the skin surface of the distal aspect of the right lateral metatarsus to perform motion cycle (MC) sequencing. Ten digital infrared cameras (Eagle Digital Real‐Time System; Motion Analysis Corporation, Santa Rosa, CA) recorded the motion of the marker. Data were captured and analyzed using a personal computer and motion‐ analysis program (EVaRT, version 5.0.4; Motion Analysis Corporation). sEMG Muscle potentials were recorded by a telemetric unit (Telemyo 8/16; Noraxon USA, Inc., Scottsdale, AZ). Self‐adhesive surface electrodes (Blue Sensor; Ambu, Ballerup, Denmark) were positioned and glued onto the shaved skin of the right pelvic limb. The muscles examined were the VL, the cranial part of the BF, and the GM. For each muscle, 2 electrodes were placed 1 cm apart with the dog in a standing position and the feet positioned squarely underneath the body. The same examiner placed the electrodes onto each muscle to ensure exact positioning. For the BF muscle, the electrodes were placed in the middle third of the distance between the ischial tuberosity and patella. For the VL muscle, the distance between the iliac crest and patella and between the patella and greater trochanter were measured.13 The central points of these lines were connected, and the electrodes were placed in the center of the resulting line. For the GM muscle, the electrodes were placed at the midpoint of the distance between the iliac crest and greater trochanter. All sEMG measurements were performed at 1200 Hz. Measurement Procedure All measurements were performed on a horse treadmill (Mustang 2200; Graber AG, Fahrwangen, Switzerland) to ensure a constant and reproducible testing area. The treadmill was locked and stationary during all measurements. The slope
Veterinary Surgery 44 (2015) 588–595 © Copyright 2014 by The American College of Veterinary Surgeons
589
Surface Electromyography in Sound Dogs During Walking and Specific Exercises
was inclined and declined to allow for walking uphill and downhill, respectively. Ten cameras were placed around the measurement area, and kinematic and sEMG measurements were performed as described by Bockstahler et al.6 and Holler et al.14 Five height‐adjustable cavaletti (timber jumps) were positioned as obstacles within the testing area. Five assessments of each dog were performed during consecutive walking over ground, uphill and downhill walking, and walking over obstacles. All exercises were performed in the same order with a 10‐min break to allow for rebuilding of the testing area after each exercise. Before the testing sessions were recorded, the dogs’ owners helped to acclimatize the dogs to the environment by guiding them through the testing area 3–5 times, depending on the dog. The treadmill was adjusted to 11% (angle, 9.9°) to produce an uphill or downhill slope. For the cavaletti exercise, the obstacles were adjusted to the height of the dogs’ carpal joints from the ground. The distance between each obstacle was set accordingly to the distance between the thoracic limb and pelvic limb of each dog.14 Dogs were allowed to comfortably walk at their own speed. Each dog’s velocity during each activity varied: 1.06 0.21 m/s for normal walking, 1.07 0.17 m/s for uphill walking, 1.10 0.16 m/s for downhill walking, and 0.89 0.11 m/s for walking over obstacles. Data Processing Kinetic measurements were performed as follows. Ground reaction forces were measured at 300 Hz and analyzed with motion analysis software (SIMI Motion, version 6.5; SIMI Reality Motion Systems, Unterschleissheim, Germany). Peak vertical force (PFz), vertical impulse (IFz), and mean vertical force (MFz) were measured in each dog. The results were compared between the left and right pelvic limbs to calculate the symmetry index using the following formula (modified from Budsberg et al.17): SIx ¼ (Xl Xr)/(Xl þ Xr), where SIx ¼ the symmetry index of the parameter; Xl ¼ PFz, IFz, and MFz of the left pelvic leg; and Xr ¼ PFz, IFz, and MFz of the right pelvic leg. A value of zero represents absolute symmetry, and values of
