Research Summary by Brent Brookbush MS, PES, CES, CSCS, ACSM H/FS
Atlas of the muscle motor points for the lower limb: implications for electrical stimulation procedures and electrode positioning
Alberto Botter • Gianmose` Oprandi •Fabio Lanfranco • Stefano Allasia • Nicola A. Maffiuletti • Marco Alessandro Minetto
Eur J Appl Physiol (2011) 111:2461–2471
Reasons Why the Study was Performed:
The aim of the study was to investigate the uniformity of the muscle motor point location for lower limb muscles in healthy subjects, most often motor point sites are points where a nerve innervates a muscle. A map of the motor point sites was constructed for the muscles tested in this study. The possible implications for electrical stimulation procedures and electrode positioning different from those commonly applied for thigh and leg muscles are discussed. In this article, the possible utility of more accurate knowledge of innervations will be touched upon.
The Methodology That Was Employed:
Fifty-three healthy subjects of both genders (18–50yo) volunteered to participate in the study. The participants had no neuromuscular or skeletal impairments. There health status was assessed by medical history, physical exam, blood count and chemistry, urinalysis, and electrocardiogram. The muscle motor points in ten muscles of the lower limb were identified on the participants dominant side. The motor points in this study correspond to the location on the skin in which an electrical pulse evoked a muscle twitch with the least amount of current, identified visually and manually via palpation of the muscle at its proximal or distal tendon. These locations were identified by scanning the skin surface with a stimulation pen electrode (small size cathode: 1 cm2 surface; Globus Italia, Codogne`, Italy) using a dispersive pad on the antagonist. The pen electrode was moved over the skin, while the stimulation current was slowly increased (starting from 1 to 2 mA) by the operator until a clear muscle twitch could be observed. Then, the stimulation current was decreased to a value that could still elicit a small mechanical response by the muscle.
For each muscle, the position of the identified motorpoints was determined as absolute and relative distances along a reference line which was measured between a proximal and a distal anatomical landmark.
The results and conclusions of the investigators:
Conclusions of this study can be summarized by the following information and diagrams:
- Three different motor points were identified for the vastus lateralis muscle
- Two different motor points were identified for the rectus femoris muscle
- Two different motor points were identified for the vastus medialis muscle
- Two different motor points were identified for the biceps femoris muscle: proximal motor point excited fibers of the long head where as stimulation of the distal motor point excited fibers of the short head
- Two different motor points were identified for the tibialis anterior muscle
- One motor point was identified in all subjects for the other muscles investigated
- semitendinosus
- semimembranosus
- peroneuslongus
- medial gastrocnemius
- lateral gastrocnemius
High variability was observed for the position of the following 4 motor points:
- vastus lateralis
- biceps femoris (short head)
- semimembranosus
- medial gastrocnemius
Low variability was observed for the position of the following 4 motor points:
- vastus lateralis
- vastus medialis (proximal and distal)
- peroneus longus
Details on the function and position of each motor point is discussed in further detail in the article
Motor Point Diagram (click on link to see pictures of motor points)
A critique of the study with suggestions for further research
This type of study is an important step in creating reference materials for practitioners. The study was well done and the authors effectively used the information to create diagrams that can be easily scanned and referenced during practice. In the future, their research should continue with muscles of the upper-extremity, trunk, neck, feet, forearms, and hand. A motor point map this accurate may serve other purposes as well. Both motor points and trigger points have been attributed to activity at the neuromuscular junction. Research correlating trigger points and motor points may reveal that two separate maps is unnecessary. Further, since trigger points are not as easily identified in research (either through dissection or electric diagnostics), the motor point map may serve as a more accurate substitution for the trigger point maps currently in use. Based on my practice, the diagrams above would serve as an effective guide for release techniques, including the use of foam rolls, softballs, and other self-administered release tools.
(C) 2011 Brent Brookbush
Questions, comments, and criticisms are welcomed and encouraged